This document discusses hyperspectral imaging technologies for multi-channel fiber sensing. It evaluates the spatial and spectral imaging performance of several aberration-corrected hyperspectral imaging spectrographs. Ray trace images and focal plane maps are presented to demonstrate the spatial and spectral reproduction accuracy over the entire back focal plane. The document focuses on retro-reflective concentric imaging spectrographs and their ability to precisely reproduce spectral images from arrays of optical fibers, minimizing crosstalk between channels.
上海必和 Advancements in hyperspectral and multi-spectral ima超光谱高光谱多光谱algous
This document discusses advancements in hyperspectral and multi-spectral imaging. It begins with an abstract describing how a spectrograph's design impacts its performance. It then provides an introduction to hyperspectral imaging, describing its use in applications such as agriculture, forensics, and biomedical research. The document emphasizes that hyperspectral sensors require maintaining precise spatial and spectral integrity over a wide field of view. It evaluates different types of spectrograph designs and their ability to accurately reproduce spectral images across a focal plane without distortion or corruption between wavelengths and spatial positions.
Infrared image enhancement using wavelet transformAlexander Decker
This document summarizes an article about enhancing infrared images using wavelet transforms. It discusses how wavelet transforms can be used to separate image details into different frequency subbands. Then a homomorphic enhancement algorithm is applied to transform the details into illumination and reflectance components, amplifying the reflectance to make details more clear. Finally, an inverse wavelet transform is performed to reconstruct an enhanced infrared image with more visible details. The document provides background on infrared imaging and different infrared bands. It also reviews literature on using wavelets for target detection by exploiting scale, edge, and contrast differences between targets and clutter.
This lecture is about particle image velocimetry technique. It include discussion about the basic element of PIV setup, image capturing, laser lights, synchronize and correlation analysis.
This document discusses various photon beam dosimetry concepts and quantities used in radiation therapy treatment planning. It begins with an introduction to how dose is measured in phantoms rather than patients. Percentage depth dose (PDD) curves are defined as the dose at a given depth normalized to a reference depth. PDD depends on factors like beam energy, depth, field size, and source-surface distance. Tissue-air ratios (TARs) relate dose in a phantom to dose in free space and are independent of source-surface distance. Backscatter factors are the TAR measured at the depth of maximum dose. The document provides details on each of these quantities and their measurement and application in treatment planning.
Image Quality, Artifacts and it's Remedies in CT-Avinesh ShresthaAvinesh Shrestha
CT is one of the frequently used diagnostic imaging modalities in Radiology. Knowledge about image quality and artifacts is essential when diagnosing a patient with the help of CT images. Moreover, Radiology Technologist's should be very well aware about the ways to identify and eliminate or minimize the artifacts in CT for better image quality.
Numerical Assessment of UWB Patch Antenna for Breast Tumor DetectionIDES Editor
In this paper, numerical assessment of two UWB
planar monopole patch antennas is presented. One is disc
monopole patch antenna with rectangular-slot, which
operates from 2.8 GHz to 11.2 GHz and the second one is
rectangular patch antenna, which operates from 3.4 GHz to
14.5 GHz. These antennas perform reasonably well in terms
of return loss and radiation efficiency. Radiation patterns
are almost omni directional. We propose these antennas for
breast tumor detection and location. Microwave
Imaging(MWI) systems constructed from UWB patch
antennas can be used to construct three-dimensional profiles
of the electrical properties of the body part that is being
examined. The simulations are performed using CST
Microwave studio, an electromagnetic simulator. The
simulation results show good agreement with the
published results.
This document discusses optical coherence tomography (OCT), including its working principles, light sources used, and comparisons to other imaging modalities. OCT uses low coherence interferometry to perform high resolution, cross-sectional imaging of biological tissues. The document describes time domain OCT which scans the reference arm, and spectral domain OCT which uses a spectrometer instead. OCT has advantages over other modalities like ultrasound and MRI in providing micrometer-scale resolution and millimeter-scale imaging depths without the use of ionizing radiation.
An Efficient K-Nearest Neighbors Based Approach for Classifying Land Cover Re...IDES Editor
In recent times, researchers in the remote
sensing community have been greatly interested in
utilizing hyperspectral data for in-depth analysis of
Earth’s surface. In general, hyperspectral imaging comes
with high dimensional data, which necessitates a pressing
need for efficient approaches that can effectively process
on these high dimensional data. In this paper, we present
an efficient approach for the analysis of hyperspectral
data by incorporating the concepts of Non-linear manifold
learning and k-nearest neighbor (k-NN). Instead of
dealing with the high dimensional feature space directly,
the proposed approach employs Non-linear manifold
learning that determines a low-dimensional embedding of
the original high dimensional data by computing the
geometric distances between the samples. Initially, the
dimensionality of the hyperspectral data is reduced to a
pairwise distance matrix by making use of the Johnson's
shortest path algorithm and Multidimensional scaling
(MDS). Subsequently, based on the k-nearest neighbors,
the classification of the land cover regions in the
hyperspectral data is achieved. The proposed k-NN based
approach is evaluated using the hyperspectral data
collected by the NASA’s (National Aeronautics and Space
Administration) AVIRIS (Airborne Visible/Infrared
Imaging Spectrometer) from Kennedy Space Center,
Florida. The classification accuracies of the proposed k-
NN based approach demonstrate its effectiveness in land
cover classification of hyperspectral data.
上海必和 Advancements in hyperspectral and multi-spectral ima超光谱高光谱多光谱algous
This document discusses advancements in hyperspectral and multi-spectral imaging. It begins with an abstract describing how a spectrograph's design impacts its performance. It then provides an introduction to hyperspectral imaging, describing its use in applications such as agriculture, forensics, and biomedical research. The document emphasizes that hyperspectral sensors require maintaining precise spatial and spectral integrity over a wide field of view. It evaluates different types of spectrograph designs and their ability to accurately reproduce spectral images across a focal plane without distortion or corruption between wavelengths and spatial positions.
Infrared image enhancement using wavelet transformAlexander Decker
This document summarizes an article about enhancing infrared images using wavelet transforms. It discusses how wavelet transforms can be used to separate image details into different frequency subbands. Then a homomorphic enhancement algorithm is applied to transform the details into illumination and reflectance components, amplifying the reflectance to make details more clear. Finally, an inverse wavelet transform is performed to reconstruct an enhanced infrared image with more visible details. The document provides background on infrared imaging and different infrared bands. It also reviews literature on using wavelets for target detection by exploiting scale, edge, and contrast differences between targets and clutter.
This lecture is about particle image velocimetry technique. It include discussion about the basic element of PIV setup, image capturing, laser lights, synchronize and correlation analysis.
This document discusses various photon beam dosimetry concepts and quantities used in radiation therapy treatment planning. It begins with an introduction to how dose is measured in phantoms rather than patients. Percentage depth dose (PDD) curves are defined as the dose at a given depth normalized to a reference depth. PDD depends on factors like beam energy, depth, field size, and source-surface distance. Tissue-air ratios (TARs) relate dose in a phantom to dose in free space and are independent of source-surface distance. Backscatter factors are the TAR measured at the depth of maximum dose. The document provides details on each of these quantities and their measurement and application in treatment planning.
Image Quality, Artifacts and it's Remedies in CT-Avinesh ShresthaAvinesh Shrestha
CT is one of the frequently used diagnostic imaging modalities in Radiology. Knowledge about image quality and artifacts is essential when diagnosing a patient with the help of CT images. Moreover, Radiology Technologist's should be very well aware about the ways to identify and eliminate or minimize the artifacts in CT for better image quality.
Numerical Assessment of UWB Patch Antenna for Breast Tumor DetectionIDES Editor
In this paper, numerical assessment of two UWB
planar monopole patch antennas is presented. One is disc
monopole patch antenna with rectangular-slot, which
operates from 2.8 GHz to 11.2 GHz and the second one is
rectangular patch antenna, which operates from 3.4 GHz to
14.5 GHz. These antennas perform reasonably well in terms
of return loss and radiation efficiency. Radiation patterns
are almost omni directional. We propose these antennas for
breast tumor detection and location. Microwave
Imaging(MWI) systems constructed from UWB patch
antennas can be used to construct three-dimensional profiles
of the electrical properties of the body part that is being
examined. The simulations are performed using CST
Microwave studio, an electromagnetic simulator. The
simulation results show good agreement with the
published results.
This document discusses optical coherence tomography (OCT), including its working principles, light sources used, and comparisons to other imaging modalities. OCT uses low coherence interferometry to perform high resolution, cross-sectional imaging of biological tissues. The document describes time domain OCT which scans the reference arm, and spectral domain OCT which uses a spectrometer instead. OCT has advantages over other modalities like ultrasound and MRI in providing micrometer-scale resolution and millimeter-scale imaging depths without the use of ionizing radiation.
An Efficient K-Nearest Neighbors Based Approach for Classifying Land Cover Re...IDES Editor
In recent times, researchers in the remote
sensing community have been greatly interested in
utilizing hyperspectral data for in-depth analysis of
Earth’s surface. In general, hyperspectral imaging comes
with high dimensional data, which necessitates a pressing
need for efficient approaches that can effectively process
on these high dimensional data. In this paper, we present
an efficient approach for the analysis of hyperspectral
data by incorporating the concepts of Non-linear manifold
learning and k-nearest neighbor (k-NN). Instead of
dealing with the high dimensional feature space directly,
the proposed approach employs Non-linear manifold
learning that determines a low-dimensional embedding of
the original high dimensional data by computing the
geometric distances between the samples. Initially, the
dimensionality of the hyperspectral data is reduced to a
pairwise distance matrix by making use of the Johnson's
shortest path algorithm and Multidimensional scaling
(MDS). Subsequently, based on the k-nearest neighbors,
the classification of the land cover regions in the
hyperspectral data is achieved. The proposed k-NN based
approach is evaluated using the hyperspectral data
collected by the NASA’s (National Aeronautics and Space
Administration) AVIRIS (Airborne Visible/Infrared
Imaging Spectrometer) from Kennedy Space Center,
Florida. The classification accuracies of the proposed k-
NN based approach demonstrate its effectiveness in land
cover classification of hyperspectral data.
CT images are digitally created from x-ray data and displayed as a matrix of pixel intensities representing tissue density. Image quality is affected by factors like spatial resolution, contrast resolution, noise, and artifacts. Spatial resolution depends on pixel size, slice thickness, reconstruction filter used and is measured by the ability to resolve small objects close together. Contrast resolution allows differentiating tissues with similar densities and depends on mAs, slice thickness, reconstruction filter and patient size. Artifacts degrade image quality and must be minimized.
An Ultrasound Image Despeckling Approach Based on Principle Component AnalysisCSCJournals
This document presents a new principle component analysis (PCA)-based approach for reducing speckle noise in ultrasound images. Speckle noise inherently degrades ultrasound image quality but also contains clinically useful textural information. The proposed method segments the image, calculates the covariance matrix for each segment, averages the covariance matrices to obtain a global covariance matrix, selects the dominant eigenvectors from this matrix to form a projection matrix, projects the image segments onto this matrix to denoise them, and recombines the denoised segments. When applied to simulated and real ultrasound images, it outperformed wavelet denoising, total variation filtering, and anisotropic diffusion filtering in terms of edge preservation and noise removal while maintaining textural information, as
This document discusses laser-induced damage density measurements of optical materials. It describes:
1) Test facilities that use small Gaussian beams (~1mm diameter) and large beams (centimeter sized) to test samples.
2) Procedures for 1-on-1 tests and raster scanning tests, which involve recording energy, temporal and spatial beam profiles to determine the fluence for each shot location.
3) How damage detection is performed and how fluence and damage site maps are analyzed to determine damage density as a function of fluence.
Semi-Automatic Classification Algorithm: The differences between Minimum Dist...Fatwa Ramdani
This remote sensing e-course will focus on comparing the Minimum Distance, Maximum Likelihood, and Spectral Angle Mapper algorithms for semi-automatic classification of Landsat 8 OLI imagery in QGIS. The course will explain the concepts, demonstrate the algorithms in QGIS, and have students complete exercises to classify land cover and assess accuracy. Minimum Distance classifies pixels based on distance to class means, Maximum Likelihood uses probability, and Spectral Angle Mapper compares spectral angles insensitive to illumination.
Congenital Bucolic and Farming Region Taxonomy Using Neural Networks for Remo...DR.P.S.JAGADEESH KUMAR
This summarizes a document about classifying rural and agricultural areas using neural networks and remote sensing imagery. It discusses extracting texture features from gray scale and multispectral images to train a neural network for classification. Different features like histogram pixel intensity, texture constraints, and spatial pixel matrices were used. The neural network was able to effectively classify rural and agricultural regions by leveraging these extracted texture features from aerial images.
This document summarizes a study that estimated and removed scatter and anti-scatter grid line artifacts from images of anthropomorphic head phantoms taken with a high resolution detector and stationary anti-scatter grid. Scatter profiles were estimated by imaging the phantoms with lead markers and interpolating grayscale values under the markers. Iteratively modifying the scatter profiles minimized structured noise across the field of view, almost totally eliminating grid line artifacts. Images before and after correction showed improved contrast and contrast-to-noise ratio, demonstrating that computational tools can correct for grid artifacts even in dynamic imaging sequences.
This document summarizes a technique called structure-oriented, frequency-dependent (SOFD) filtering that can significantly increase the usable bandwidth of seismic data. The technique uses structure tensors computed from a stack to guide frequency-dependent filtering of individual frequency bands. This preserves structural features while improving signal-to-noise. The technique is demonstrated on land seismic data, improving signal quality at low and high frequencies. Well ties show the enhanced bandwidth data matches well logs, extending usable frequencies without degrading tie quality. The technique can be applied to pre-stack data by filtering offset volumes separately.
1) An experiment compared the effectiveness of an anti-scatter grid when used with a high-resolution CMOS detector (Dexela 1207 with 75 micron pixels) versus a flat panel detector (FPD, Paxscan 2020 with 194 micron pixels).
2) When the grid was used, contrast improved for both detectors but the contrast-to-noise ratio (CNR) did not increase as much for the Dexela due to a substantial increase in total noise compared to the FPD.
3) The increased noise for the Dexela was caused by higher fixed pattern noise from the grid lines, as the quantum noise increase from radiation attenuation should have been similar for both detectors. Without
IJCER (www.ijceronline.com) International Journal of computational Engineerin...ijceronline
This document summarizes a research paper that proposes a computer-aided diagnosis (CAD) system for detecting lung cancer nodules from chest CT images using support vector machines (SVM). The CAD system involves 5 main phases: 1) image pre-processing using total variation denoising, 2) lung region segmentation using optimal thresholding and morphological operations, 3) feature extraction of lung nodules using gray level co-occurrence matrix (GLCM) texture analysis, 4) SVM classification of nodules as benign or malignant, 5) output of classification results. The goal is to develop an automated CAD system to assist radiologists in early detection of lung cancer from CT images.
This white paper discusses optimizing image quality and dose when transitioning from computed radiography (CR) to digital radiography (DR). Key factors discussed include:
1) DR detector panel technologies like cesium iodide needle phosphors can improve image quality and reduce radiation dose compared to CR powder phosphors.
2) Pixel size, fill factor, and readout electronics influence image noise, with smaller pixel sizes and higher fill factors improving quality.
3) Image processing software, grid selection and alignment, collimation, and exposure monitoring are important to maximize the benefits of DR.
4) Case studies show transitioning to DR can increase productivity and patient throughput while achieving dose reduction goals. Proper
This document discusses factors that impact the image quality in CT scans. It describes key scanning parameters like milliampere, scan time, slice thickness, and reconstruction algorithm that determine image quality. Higher mA and shorter scan times improve image quality but increase radiation dose. Thinner slice thickness and smaller pixel size enhance spatial resolution. The modulation transfer function is used to evaluate a system's ability to resolve fine detail spatially. Selection of these parameters requires balancing optimal image quality with minimizing radiation dose to the patient.
This document describes the design and fabrication of flat helical nanosieve devices that can fully manipulate optical vortices. The nanosieves achieve complex control of optical vortex beams through spatially rotating nanovoids that introduce geometric phase shifts. This allows the generation, hybridization, spatial multiplexing, focusing and nondiffractive propagation of optical vortices to be controlled. Unlike conventional methods, the multifunctional flat helical nanosieves provide unique extensibility and flexibility for manipulating the orbital angular momentum of light within an ultrathin interface.
This document describes research on using near-infrared optical imaging techniques for 3D biological tissue imaging. It discusses diffuse optical tomography (DOT) and fluorescence DOT (F-DOT). For DOT, it covers the photon diffusion equation, forward and inverse models, and finite element method implementation. For F-DOT, it discusses the fluorescence transport equations and parallel inversion schemes. Simulation results using MATLAB and NIRFAST show reconstructed optical property maps and fluorescence distributions in 2D and 3D geometries. Future work aims to further develop 3D imaging software for interfacing with DOT instrumentation.
This document proposes a technology using magneto-optic thin film sensors to study magnetic fields in deep space through wide-area arrays deployed by spacecraft. Each sensor would measure local magnetic fields and disturbances, with data communicated to reconstruct magnetic activity over large regions. The arrays could also control large space systems through parallel computing principles. The sensors use bismuth-substituted iron-garnet films that respond to magnetic fields through the magneto-optic Faraday effect, providing high sensitivity and domain wall velocity. Deployed arrays would allow unprecedented magnetic mapping beyond spacecraft's direct reach.
The document discusses factors that affect medical image quality, including contrast, resolution, noise, and artifacts. It describes how image quality is determined by the imaging method, equipment characteristics, and imaging variables. It then explains several key factors in more detail:
- Contrast is affected by subject properties like tissue characteristics as well as acquisition factors like x-ray energy. Contrast can also be impacted by processing and display.
- Resolution is determined by an imaging system's ability to differentiate objects and is measured by the point spread function and modulation transfer function.
- Noise originates from imaging system sources and can degrade images, though acquisition parameters and reconstruction techniques can help reduce it.
- Artifacts are irregular image
Computationally Efficient Methods for Sonar Image Denoising using Fractional ...CSCJournals
Sonar images produced due to the coherent nature of scattering phenomenon inherit a multiplicative component called speckle and contain almost homogeneous as well as textured regions with relatively rare edges. Speckle removal is a pre-processing step required in applications like the detection and classification of objects in the sonar image. In this paper computationally efficient Fractional Integral Mask algorithms to remove the speckle noise from sonar images is proposed. Riemann- Liouville definition of fractional calculus is used to create Fractional integral masks in eight directions. The use of a mask incorporated with the significant coefficients from the eight directional masks and a single convolution operation required in such case helps in obtaining the computational efficiency. The sonar image heterogeneous patch classification is based on a new proposed naive homogeneity index which depends on the texture strength of the patches and despeckling filters can be adjusted to these patches. The application of the mask convolution only to the selected patches again reduce the computational complexity. The non-homomorphic approach used in the proposed method avoids the undesired bias occurring in the traditional homomorphic approach. Experiments show that the mask size required directly depends on the fractional order. Mask size can be reduced for lower fractional orders thus ensuring the computation complexity reduction for lower orders. Experimental results substantiate the effectiveness of the despeckling method. The different non reference image performance evaluation criterion are used to evaluate the proposed method.
Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Re...iosrjce
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Applications for high speed Raman Microscopynweavers
The RAMAN-11 is a new generation of laser Raman microscope developed by Nanophoton that enables the fastest high definition Raman imaging. It combines laser microscope and Raman spectroscopy technologies. The RAMAN-11's imaging speed is 300-600 times faster than competitors and it opens up new applications. Its software supports rapid data acquisition and robust analysis functions.
compiter radiography and digital radiography Unaiz Musthafa
This document discusses computed radiography (CR) and digital radiography (DR). CR uses reusable imaging plates instead of film, which are read by a laser scanner. DR uses a digital detector incorporated into x-ray equipment to provide direct digital output. Both have greater exposure latitude than screen-film and allow computer post-processing to enhance images. Technologists must monitor exposure indices to avoid overexposure with CR and DR systems. The document also covers digital fluoroscopy techniques like frame averaging.
This document outlines a student project to develop a system to detect non-metallic weapons on passengers at airports using infrared light and image processing. The student aims to enhance airport security by detecting hidden plastic guns. The project proposes using a CCD sensor and infrared light to create digital images that can then be analyzed using particle analysis tools to identify threats. Initial testing showed some success in detecting plastic objects but identified challenges around orientation, lighting, and distance that need further refinement.
This document describes an obstacle avoiding robot with a vacuum cleaner. The robot uses IR sensors and a microcontroller to detect obstacles and navigate around them while using a blower to function as a vacuum cleaner. It discusses the components, circuit diagram, software, applications and future enhancements such as adding a camera to increase range or modifying it to function as a firefighting robot. The goal is to create a robot that can autonomously clean an area while avoiding obstacles.
CT images are digitally created from x-ray data and displayed as a matrix of pixel intensities representing tissue density. Image quality is affected by factors like spatial resolution, contrast resolution, noise, and artifacts. Spatial resolution depends on pixel size, slice thickness, reconstruction filter used and is measured by the ability to resolve small objects close together. Contrast resolution allows differentiating tissues with similar densities and depends on mAs, slice thickness, reconstruction filter and patient size. Artifacts degrade image quality and must be minimized.
An Ultrasound Image Despeckling Approach Based on Principle Component AnalysisCSCJournals
This document presents a new principle component analysis (PCA)-based approach for reducing speckle noise in ultrasound images. Speckle noise inherently degrades ultrasound image quality but also contains clinically useful textural information. The proposed method segments the image, calculates the covariance matrix for each segment, averages the covariance matrices to obtain a global covariance matrix, selects the dominant eigenvectors from this matrix to form a projection matrix, projects the image segments onto this matrix to denoise them, and recombines the denoised segments. When applied to simulated and real ultrasound images, it outperformed wavelet denoising, total variation filtering, and anisotropic diffusion filtering in terms of edge preservation and noise removal while maintaining textural information, as
This document discusses laser-induced damage density measurements of optical materials. It describes:
1) Test facilities that use small Gaussian beams (~1mm diameter) and large beams (centimeter sized) to test samples.
2) Procedures for 1-on-1 tests and raster scanning tests, which involve recording energy, temporal and spatial beam profiles to determine the fluence for each shot location.
3) How damage detection is performed and how fluence and damage site maps are analyzed to determine damage density as a function of fluence.
Semi-Automatic Classification Algorithm: The differences between Minimum Dist...Fatwa Ramdani
This remote sensing e-course will focus on comparing the Minimum Distance, Maximum Likelihood, and Spectral Angle Mapper algorithms for semi-automatic classification of Landsat 8 OLI imagery in QGIS. The course will explain the concepts, demonstrate the algorithms in QGIS, and have students complete exercises to classify land cover and assess accuracy. Minimum Distance classifies pixels based on distance to class means, Maximum Likelihood uses probability, and Spectral Angle Mapper compares spectral angles insensitive to illumination.
Congenital Bucolic and Farming Region Taxonomy Using Neural Networks for Remo...DR.P.S.JAGADEESH KUMAR
This summarizes a document about classifying rural and agricultural areas using neural networks and remote sensing imagery. It discusses extracting texture features from gray scale and multispectral images to train a neural network for classification. Different features like histogram pixel intensity, texture constraints, and spatial pixel matrices were used. The neural network was able to effectively classify rural and agricultural regions by leveraging these extracted texture features from aerial images.
This document summarizes a study that estimated and removed scatter and anti-scatter grid line artifacts from images of anthropomorphic head phantoms taken with a high resolution detector and stationary anti-scatter grid. Scatter profiles were estimated by imaging the phantoms with lead markers and interpolating grayscale values under the markers. Iteratively modifying the scatter profiles minimized structured noise across the field of view, almost totally eliminating grid line artifacts. Images before and after correction showed improved contrast and contrast-to-noise ratio, demonstrating that computational tools can correct for grid artifacts even in dynamic imaging sequences.
This document summarizes a technique called structure-oriented, frequency-dependent (SOFD) filtering that can significantly increase the usable bandwidth of seismic data. The technique uses structure tensors computed from a stack to guide frequency-dependent filtering of individual frequency bands. This preserves structural features while improving signal-to-noise. The technique is demonstrated on land seismic data, improving signal quality at low and high frequencies. Well ties show the enhanced bandwidth data matches well logs, extending usable frequencies without degrading tie quality. The technique can be applied to pre-stack data by filtering offset volumes separately.
1) An experiment compared the effectiveness of an anti-scatter grid when used with a high-resolution CMOS detector (Dexela 1207 with 75 micron pixels) versus a flat panel detector (FPD, Paxscan 2020 with 194 micron pixels).
2) When the grid was used, contrast improved for both detectors but the contrast-to-noise ratio (CNR) did not increase as much for the Dexela due to a substantial increase in total noise compared to the FPD.
3) The increased noise for the Dexela was caused by higher fixed pattern noise from the grid lines, as the quantum noise increase from radiation attenuation should have been similar for both detectors. Without
IJCER (www.ijceronline.com) International Journal of computational Engineerin...ijceronline
This document summarizes a research paper that proposes a computer-aided diagnosis (CAD) system for detecting lung cancer nodules from chest CT images using support vector machines (SVM). The CAD system involves 5 main phases: 1) image pre-processing using total variation denoising, 2) lung region segmentation using optimal thresholding and morphological operations, 3) feature extraction of lung nodules using gray level co-occurrence matrix (GLCM) texture analysis, 4) SVM classification of nodules as benign or malignant, 5) output of classification results. The goal is to develop an automated CAD system to assist radiologists in early detection of lung cancer from CT images.
This white paper discusses optimizing image quality and dose when transitioning from computed radiography (CR) to digital radiography (DR). Key factors discussed include:
1) DR detector panel technologies like cesium iodide needle phosphors can improve image quality and reduce radiation dose compared to CR powder phosphors.
2) Pixel size, fill factor, and readout electronics influence image noise, with smaller pixel sizes and higher fill factors improving quality.
3) Image processing software, grid selection and alignment, collimation, and exposure monitoring are important to maximize the benefits of DR.
4) Case studies show transitioning to DR can increase productivity and patient throughput while achieving dose reduction goals. Proper
This document discusses factors that impact the image quality in CT scans. It describes key scanning parameters like milliampere, scan time, slice thickness, and reconstruction algorithm that determine image quality. Higher mA and shorter scan times improve image quality but increase radiation dose. Thinner slice thickness and smaller pixel size enhance spatial resolution. The modulation transfer function is used to evaluate a system's ability to resolve fine detail spatially. Selection of these parameters requires balancing optimal image quality with minimizing radiation dose to the patient.
This document describes the design and fabrication of flat helical nanosieve devices that can fully manipulate optical vortices. The nanosieves achieve complex control of optical vortex beams through spatially rotating nanovoids that introduce geometric phase shifts. This allows the generation, hybridization, spatial multiplexing, focusing and nondiffractive propagation of optical vortices to be controlled. Unlike conventional methods, the multifunctional flat helical nanosieves provide unique extensibility and flexibility for manipulating the orbital angular momentum of light within an ultrathin interface.
This document describes research on using near-infrared optical imaging techniques for 3D biological tissue imaging. It discusses diffuse optical tomography (DOT) and fluorescence DOT (F-DOT). For DOT, it covers the photon diffusion equation, forward and inverse models, and finite element method implementation. For F-DOT, it discusses the fluorescence transport equations and parallel inversion schemes. Simulation results using MATLAB and NIRFAST show reconstructed optical property maps and fluorescence distributions in 2D and 3D geometries. Future work aims to further develop 3D imaging software for interfacing with DOT instrumentation.
This document proposes a technology using magneto-optic thin film sensors to study magnetic fields in deep space through wide-area arrays deployed by spacecraft. Each sensor would measure local magnetic fields and disturbances, with data communicated to reconstruct magnetic activity over large regions. The arrays could also control large space systems through parallel computing principles. The sensors use bismuth-substituted iron-garnet films that respond to magnetic fields through the magneto-optic Faraday effect, providing high sensitivity and domain wall velocity. Deployed arrays would allow unprecedented magnetic mapping beyond spacecraft's direct reach.
The document discusses factors that affect medical image quality, including contrast, resolution, noise, and artifacts. It describes how image quality is determined by the imaging method, equipment characteristics, and imaging variables. It then explains several key factors in more detail:
- Contrast is affected by subject properties like tissue characteristics as well as acquisition factors like x-ray energy. Contrast can also be impacted by processing and display.
- Resolution is determined by an imaging system's ability to differentiate objects and is measured by the point spread function and modulation transfer function.
- Noise originates from imaging system sources and can degrade images, though acquisition parameters and reconstruction techniques can help reduce it.
- Artifacts are irregular image
Computationally Efficient Methods for Sonar Image Denoising using Fractional ...CSCJournals
Sonar images produced due to the coherent nature of scattering phenomenon inherit a multiplicative component called speckle and contain almost homogeneous as well as textured regions with relatively rare edges. Speckle removal is a pre-processing step required in applications like the detection and classification of objects in the sonar image. In this paper computationally efficient Fractional Integral Mask algorithms to remove the speckle noise from sonar images is proposed. Riemann- Liouville definition of fractional calculus is used to create Fractional integral masks in eight directions. The use of a mask incorporated with the significant coefficients from the eight directional masks and a single convolution operation required in such case helps in obtaining the computational efficiency. The sonar image heterogeneous patch classification is based on a new proposed naive homogeneity index which depends on the texture strength of the patches and despeckling filters can be adjusted to these patches. The application of the mask convolution only to the selected patches again reduce the computational complexity. The non-homomorphic approach used in the proposed method avoids the undesired bias occurring in the traditional homomorphic approach. Experiments show that the mask size required directly depends on the fractional order. Mask size can be reduced for lower fractional orders thus ensuring the computation complexity reduction for lower orders. Experimental results substantiate the effectiveness of the despeckling method. The different non reference image performance evaluation criterion are used to evaluate the proposed method.
Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Re...iosrjce
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Applications for high speed Raman Microscopynweavers
The RAMAN-11 is a new generation of laser Raman microscope developed by Nanophoton that enables the fastest high definition Raman imaging. It combines laser microscope and Raman spectroscopy technologies. The RAMAN-11's imaging speed is 300-600 times faster than competitors and it opens up new applications. Its software supports rapid data acquisition and robust analysis functions.
compiter radiography and digital radiography Unaiz Musthafa
This document discusses computed radiography (CR) and digital radiography (DR). CR uses reusable imaging plates instead of film, which are read by a laser scanner. DR uses a digital detector incorporated into x-ray equipment to provide direct digital output. Both have greater exposure latitude than screen-film and allow computer post-processing to enhance images. Technologists must monitor exposure indices to avoid overexposure with CR and DR systems. The document also covers digital fluoroscopy techniques like frame averaging.
This document outlines a student project to develop a system to detect non-metallic weapons on passengers at airports using infrared light and image processing. The student aims to enhance airport security by detecting hidden plastic guns. The project proposes using a CCD sensor and infrared light to create digital images that can then be analyzed using particle analysis tools to identify threats. Initial testing showed some success in detecting plastic objects but identified challenges around orientation, lighting, and distance that need further refinement.
This document describes an obstacle avoiding robot with a vacuum cleaner. The robot uses IR sensors and a microcontroller to detect obstacles and navigate around them while using a blower to function as a vacuum cleaner. It discusses the components, circuit diagram, software, applications and future enhancements such as adding a camera to increase range or modifying it to function as a firefighting robot. The goal is to create a robot that can autonomously clean an area while avoiding obstacles.
The document describes a new filterless color imaging sensor that combines advantages of CMOS and CCD sensors. It is small, low cost, high resolution, and high sensitivity with low power consumption. The sensor relies on wavelength penetration into silicon to detect red, green, and blue colors at each pixel without using optical filters. This simple innovation seeks partners for further development and market deployment in applications like mobile phones, cameras, robotics and medical imaging.
The document summarizes and compares several robots created for artistic purposes. Translator II is a robot created by Sabrina Raaf that uses a CO2 sensor to monitor air quality and draws pictures based on CO2 levels, providing a record of environmental conditions over time. Profiler is an interactive robot installation by Robotlab that exposes humans to industrial robots in a public setting. Fish, Plant, Rack is an artwork by Andy Gracie featuring interaction between a fish, plant and robot controlled by an AI microcontroller.
The document summarizes two approaches to implementing foveated imaging in CMOS image sensors: (1) A pyramidal architecture with multiple rings of pixels having different integration times, allowing for dynamic range enhancement. (2) A universal multiresolution sensor using a 3T pixel design that allows pixels to be grouped and averaged, enabling adaptive resolution. Both designs aim to mimic the human retina and improve efficiency over traditional sensors. The pyramidal and multiresolution sensors were fabricated in 0.18um CMOS technology and are being tested for applications like video conferencing and industrial inspection.
The document describes a new filterless color imaging sensor that combines advantages of CMOS and CCD sensors. It is small, low cost, high resolution, and high sensitivity with low power consumption. The sensor relies on wavelength penetration into silicon to detect red, green, and blue colors at each pixel without using optical filters. This simple innovation allows for a 4 megapixel sensor the size of a current 2 megapixel phone sensor. The technology was developed at a Canadian academic institution and the researchers are seeking partnerships for further development and market deployment.
http://www.axis.com/
When an image is being captured by a network camera, light passes through the lens and falls on the
image sensor. The image sensor consists of picture elements, also called pixels, that register the amount
of light that falls on them. They convert the received amount of light into a corresponding number of
electrons. The stronger the light, the more electrons are generated. The electrons are converted into
voltage and then transformed into numbers by means of an A/D-converter. The signal constituted by the
numbers is processed by electronic circuits inside the camera.
Sensors are devices that measure physical quantities and convert them into signals that can be read by observers or instruments. There are many types of sensors for measuring things like temperature, pressure, sound, motion, light, and more. Sensors work by being sensitive only to the property they are measuring. New microscopic sensors called microsensors can achieve high speeds and sensitivities. Some common sensors include thermometers, microphones, motion detectors, and sensors in cars that measure things like engine temperature, tire pressure, and vehicle speed.
This document discusses image sensors, including what they are, their history, types (CCD and CMOS), and applications. An image sensor converts light into digital signals and contains millions of photosensitive diodes. The two main types are CCDs, which store and transfer electrons, and CMOS sensors, which can incorporate additional circuits. While CCDs generally have better image quality in low light, CMOS sensors are smaller, cheaper, and more power efficient. Image sensors are now widely used in applications like digital cameras, camcorders, PDAs, fingerprint scanners, and more.
Reduction of Azimuth Uncertainties in SAR Images Using Selective RestorationIJTET Journal
The document proposes a framework to reduce azimuth uncertainties in synthetic aperture radar (SAR) images. It identifies azimuth uncertainty using a local average SAR image, system parameters, and a metric from the azimuth antenna pattern. Uncertainties are classified as isolated or clustered based on size. Isolated ambiguities consisting of smaller interconnected pixel regions are restored using compressive imaging. Clustered ambiguities consisting of larger interconnected pixel regions are restored using exemplar-based image inpainting. The proposed method was tested on real TerraSAR-X data and was able to effectively remove azimuth uncertainties and enhance image quality.
URBAN AREA PRODUCT SIMULATION FOR THE ENMAP HYPERSPECTRAL SENSOR.pptgrssieee
1) The document discusses the potential of hyperspectral sensors like EnMAP for urban monitoring tasks, which is challenging due to mixed pixels from heterogeneous land covers.
2) It creates realistic EnMAP images by degrading the spatial resolution of urban scene images and applies classification methods.
3) The results show that while classification accuracy decreases significantly with lower resolution, spectral unmixing techniques can improve accuracy by exploiting sub-pixel information. However, the utility of hyperspectral data depends on the target application given resolution trade-offs.
URBAN AREA PRODUCT SIMULATION FOR THE ENMAP HYPERSPECTRAL SENSOR.pptgrssieee
1) The document discusses the potential of hyperspectral sensors like EnMAP for urban monitoring tasks, which is challenging due to mixed pixels from heterogeneous land covers.
2) It creates realistic EnMAP images by degrading the spatial resolution of urban scene images and applies classification methods.
3) The results show that while classification accuracy decreases significantly with lower resolution, spectral unmixing techniques can improve accuracy by exploiting sub-pixel information. However, the utility of hyperspectral data depends on the target application given resolution trade-offs.
Characterization of Photonic Crystal FiberSurbhi Verma
Photonic-crystal fiber (PCF) is a new class of optical fiber based on the properties of photonic crystals. Because of its ability to confine light in hollow cores or with confinement characteristics not possible in conventional optical fiber, PCF is now finding applications in fiber-optic communications, fiber lasers, nonlinear devices, high-power transmission, highly sensitive gas sensors, and other areas.
In this project, photonic crystal fibers and far field measurement technique was described. The project also focused on the development of analytical formulae and a method to characterize PCF from its far field radiation pattern using effective index approach considering PCF to be similar to single mode step index fiber. This project was an explanation of an already published research paper
The document discusses potential future works building upon the research presented in the book. It describes how a wide field of view imaging system with polarization sensitivity could enable applications in security, robot navigation, and endoscopy. It also discusses how improving the angular resolution and developing algorithms to calculate distance traveled could allow for real-time material classification, navigation, and sun position detection for autonomous agents.
The document discusses potential future works building upon the research presented in the book. It proposes:
1) Developing a wide-field of view imaging system with polarization sensitivity that could enable applications like security, robot navigation, and endoscopy.
2) Creating a high angular resolution imaging system with polarization sensitivity that could provide more accurate polarization measurements and material classification in real-time.
3) Enhancing navigation algorithms by computing distance traveled in addition to direction from polarized light, allowing egocentric navigation computations on-chip.
This document provides a summary of a seminar report on the design of an ultra-wideband (UWB) radar system for concealed weapon detection. The system uses frequency-modulated continuous wave (FMCW) radar with a multi-channel receiver scheme. Simulation results showed that by properly selecting and positioning filters, it is possible to achieve satisfactory performance in terms of harmonic suppression, target detection, and range resolution. The document discusses the feasibility and design of the UWB FMCW radar system, including requirements, frequency band selection, antenna array design, noise and performance analyses, and circuit simulations. The overall goal is to develop a low-cost, high-resolution radar sensor for security screening applications.
This document summarizes hyperspectral image classification. It begins by introducing hyperspectral imagery, noting that these images contain narrow spectral bands over a continuous spectral range, capturing characteristics of electromagnetic radiation. The document then discusses supervised and unsupervised classification techniques. Supervised classification involves identifying training samples to develop statistical characterizations of information classes. Unsupervised classification partitions images into homogeneous spectral clusters. The document focuses on supervised classification and discusses support vector machines, a commonly used algorithm that maps data into a higher dimensional space to perform linear classification.
Tomographic reconstruction in nuclear medicineSUMAN GOWNDER
This document discusses various techniques for tomographic reconstruction in nuclear medicine imaging. It begins with an overview of backprojection and Fourier-based reconstruction techniques like simple backprojection, direct Fourier transform reconstruction, and filtered backprojection. It then discusses multislice imaging, factors that influence image quality, and iterative reconstruction algorithms as an alternative to filtered backprojection. Finally, it covers reconstruction of fan-beam, cone-beam, and pinhole SPECT data that require 3D reconstruction algorithms.
This document discusses hyperspectral imaging techniques and Headwall Photonics' hyperspectral sensors. Hyperspectral imaging captures precise spectral data over a spatial area simultaneously, providing advantages over single point sensors. Headwall Photonics' hyperspectral sensors use push-broom scanning or fiber optic collection to obtain spectral images. These sensors have been used in applications such as tissue scanning, hazardous materials detection, and aerospace. Headwall Photonics provides flexible sensor designs to meet various application needs for hyperspectral imaging.
Purkinje imaging for crystalline lens density measurementPetteriTeikariPhD
Brief introduction for the non-invasive, inexpensive and fast Purkinje image -based method for measuring the spectral transmittance of the human crystalline lens density in vivo.
Alternative download link:
https://www.dropbox.com/s/588y7epy13n34xo/purkinje_imaging.pdf?dl=0
This document provides a review of pansharpening methods for multispectral images. It begins with an introduction that describes how multispectral images have both panchromatic and multispectral bands at different spatial resolutions. Pansharpening aims to increase the spatial resolution of the multispectral bands using the panchromatic band. The document then reviews various classical and state-of-the-art pansharpening methods, classifying them and describing their characteristics. It also discusses how to evaluate pansharpening quality both visually and quantitatively. Pre-processing steps like registration, upsampling and histogram matching that are often required before pansharpening are also covered.
A new single grating spectrograph for ultra violet raman scattering studiesJohn Clarkson
This document describes a new single grating spectrograph designed for deep ultraviolet (DUV) Raman scattering studies. Key features include:
- It uses two identical calcium fluoride camera lenses, each with five optical elements, to collimate and focus the DUV Raman scattered light onto a charge coupled device (CCD) detector.
- A novel edge filter provides sharp cutoff around 450 cm-1 to reject Rayleigh scattering while transmitting Stokes Raman photons.
- Initial tests show it can rapidly collect Stokes DUV Raman signals with good signal-to-noise ratios using a 257 nm excitation laser in a backscattering configuration.
- Example spectra are presented of chemicals like cyclohexane and glucose to illustrate
Abstract
Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal
sample preparation requirements and its ability to “see” below the surface. Another important property is the ability
to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed
at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a
resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D
image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for
reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis
of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis
was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle
size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported
non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.
Design and Simulation of Narrow Beamwidth Dipole Array Antenna for Microwave ...IRJET Journal
This document describes a proposed design for a narrow beamwidth dipole array antenna for microwave imaging applications. The antenna array uses 11 dipole elements with excitation amplitudes determined by the binomial method and phases determined by the Woodward-Lawson method. Simulation results show the antenna has a return loss of -19.78 dB, bandwidth of 1.9 GHz, main lobe gain of 10.53 dB, half power beamwidth of 18.9 degrees, and minimum sidelobe gain of -69.2 dB. The proposed design aims to provide a safer alternative to X-ray imaging with greater diagnostic precision than ultrasound.
MODELING STUDY OF LASER BEAM SCATTERING BY DEFECTS ON SEMICONDUCTOR WAFERSjmicro
Accurate modeling of light scattering from nanometer scale defects on Silicon wafersiscritical for enabling
increasingly shrinking semiconductor technology nodes of the future. Yet, such modeling of defect
scattering remains unsolved since existing modeling techniques fail to account for complex defect and
wafer geometries. Here, we present results of laser beam scattering from spherical and ellipsoidal
particles located on the surface of a silicon wafer. A commercially available electromagnetic field solver
(HFSS) was deployed on a multiprocessor cluster to obtain results with previously unknown accuracy
down to light scattering intensity of -170 dB. We compute three dimensional scattering patterns of silicon
nanospheres located on a semiconductor wafer for both perpendicular and parallel polarization and show
the effect of sphere size on scattering. We further computer scattering patterns of nanometer scale
ellipsoidal particles having different orientation angles and unveil the effects of ellipsoidal orientation on
scattering.
This document summarizes the development and commissioning of a next generation x-ray beam size monitor (NGXBSM) at the Cornell Electron Storage Ring (CESR). Key aspects include:
1) Designing and installing new vacuum components like a flared vacuum chamber, beamline crotch, and beryllium window to transfer x-rays from CESR to the detector.
2) Designing and constructing a new two-pole electromagnet source to provide x-rays at lower CESR beam energies of 2.085 GeV.
3) Integrating the NGXBSM permanently in CESR to allow continuous operation, including modifying accelerator optics and realign
In light microscopy, illuminating light is passed through the sample as uniformly as possible over the field of view. For thicker samples, where the objective lens does not have sufficient depth of focus, light from sample planes above and below the focal plane will also be detected. The out of focus light will add blur to the image reducing the resolution. In fluorescence microscopy, any dye molecules in the field of view will be stimulated, including those in out-of-focus planes. Confocal microscopy provides a means of rejecting the out-of-focus light from the detector such that it does not contribute blur to the images being collected. This technique allows for high-resolution imaging in thick tissues.
In a confocal microscope, the illumination and detection optics are focused on the same diffraction limited spot in the sample, which is the only spot imaged by the detector during a confocal scan. To generate a complete image, the spot must be moved over the sample and data collected point by point.
A significant advantage of the confocal microscope is the optical sectioning provided, which allows for 3D reconstruction of a sample from high-resolution stacks of images. The primary functions of a confocal microscope are to produce a point source of light and reject out-of-focus light, which provides the ability to image deep into tissues with high resolution, and optical sectioning for 3D reconstructions of imaged samples. The basic principle include illumination and detection optics are focused on the same diffraction-limited spot, which is moved over the sample to build the complete image on the detector. The entire field of view is illuminated during confocal imaging, anything outside the focal plane contributes little to the image, lessening the haze observed in standard light microscopy with thick and highly-scattering samples, and providing optical sectioning.
This document presents a summary of a research paper on shape from focus. Shape from focus is a technique that uses differences in focus levels across a series of images to obtain depth information and reconstruct the 3D shape of an object. The paper develops a sum-modified Laplacian (SML) operator to provide local measures of image focus quality. The SML operator is applied to images captured at different focus levels to determine focus measures. A depth estimation algorithm then interpolates the focus measures to obtain accurate depth estimates for each point. Results show the SML operator provides robust focus measures and the overall shape from focus approach can effectively reconstruct shapes, making it suitable for challenging visual inspection problems.
This document summarizes a student project that developed an apparatus to measure the coherence length of lasers using a modified Michelson interferometer. The apparatus was used to compare the coherence lengths of a diode laser and He-Ne laser. Fringes produced by scanning the adjustable mirror demonstrated that visibility decreased more for the diode laser, indicating its shorter coherence length compared to the He-Ne laser. The project provides results of the interference patterns produced and confirms the diode laser has a wider bandwidth based on the models and data collected.
Similar to 上海必和 Advances-hyperspectral-imaging0409超光谱高光谱多光谱 (20)
The document describes seven circular dichroism spectrometer models:
1) The Olis DSM 17 CD UV/Vis[NIR] spectrometer has the widest spectral range of 185-2600 nm and computer-controlled slit width.
2) The Olis DSM 20 CD UV/Vis[NIR] spectrometer is the smallest and most versatile, designed for diverse layouts.
3) The Olis DSM 1000 CD UV/Vis[NIR] rapid-scanning spectrometer is the only model that can rapidly scan, providing potential for novel experiments.
The Measuring System Lambda enables measuring the thermal conductivity of fluids, powders, gels and nano particles from -30°C to 190°C without an external cryostat. It can measure down to -50°C with a precooler and up to 35 bars of pressure. Automated measurements are controlled via PC software to provide fast, graphical and tabular results in Excel format for various measurement modes.
Hyperspectral imaging is an analytical technique useful for life sciences and biotechnology applications. Headwall's Hyperspec instruments allow for accurate spectral analysis and high-throughput screening. Key advantages of hyperspectral imaging include material classification, color rendering of images based on spectral signatures, and generating wavelength-specific criteria for high-speed analysis.
This document discusses hyperspectral microscopy, which combines microscopy and spectral imaging to produce data-rich views of biological structures. Hyperspectral microscopy grew from combining microspectrophotometry and spectral remote sensing. Recent advances integrated hardware and software to enable commercial hyperspectral microscopy systems. The document describes a hyperspectral microscope developed to study nanoparticles, which provides brighter dark-field illumination than conventional methods and enables spectral analysis of particle clusters. Applications demonstrated include identifying titanium dioxide nanoparticles and analyzing anthrax spores.
Congressman John Olver announced that the U.S. House approved $2.5 million in funding for hyperspectral imaging technology to be developed by Headwall Photonics. The funding will allow Headwall to design and manufacture new miniature chemical imaging sensors for small UAVs and UGVs, helping the military monitor regions safely. Congressman Olver secured the funding and said that Headwall is an innovative company that provides greater capabilities without risking soldiers. The CEO of Headwall thanked Olver for his long-term support of the local manufacturer.
上海必和 Asia pacific food industry - headwall hyperspectral超光谱高光谱多光谱algous
Hyperspectral imaging is being increasingly used as a key sensor technology for food inspection. It allows detection of conditions like bruises, diseases, and contaminants that may not be visible to the naked eye. Food producers can screen out lower quality products before processing using this technology. Researchers have worked to develop hyperspectral instruments specifically for food safety applications. The technology provides detailed chemical signatures that allow inspection and analysis of attributes like ripeness, tenderness, and disease detection in foods like fruit, meat, and poultry. This helps improve process control and quality along production lines.
Headwall Photonics and Andor Technology have formed an international partnership where Andor will distribute and sell Headwall's Raman Explorer and Raman Discovery spectral imaging products worldwide. The partnership will provide Headwall access to new international markets and applications, while Andor gains access to Headwall's innovative spectrometer designs that combine with Andor cameras to enable leading Raman and hyperspectral imaging capabilities. The Raman Explorer and Discovery products are optimized for demanding Raman applications requiring high throughput, dynamic range, and spectral and spatial resolution.
CytoViva developed a microscopy system that allows researchers to better view nanoparticles and their interactions. This system combines innovations in illumination, fluorescence detection, and an environmental chamber. Separately, the military had created hyperspectral imaging software to identify targets using their unique light scattering signatures. CytoViva realized this software could help researchers identify unknown nanoparticles visible through their microscope. By coupling their microscope with this military software, CytoViva is changing how researchers study nanoparticles and their role in cancer and other diseases.
Photonics technologies are helping improve agriculture in several ways:
1) Infrared sensing helps determine soil health and hydrology while 3D laser scanning allows non-destructive measurement of soil density.
2) Remote sensing from planes and satellites estimates crop yields and monitors plant health through measurements of chlorophyll, nitrogen levels, and evapotranspiration.
3) Fiber optic sensors and spectroscopy determine sugar levels in grapes to optimize harvest times and ensure food safety.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
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LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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Training: ISO/IEC 27001 Information Security Management System - EN | PECB
ISO/IEC 42001 Artificial Intelligence Management System - EN | PECB
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This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
1. Advances in Hyperspectral Imaging Technologies
for Multi-channel Fiber Sensing
Jay Zakrzewski*, Kevin Didona
Headwall Photonics, Inc., 601 River Street, Fitchburg, MA, USA 01420
ABSTRACT
A spectrograph’s design, e.g. the opto-mechanical system beginning at the entrance slit, and ending at the back focal
plane position, directly impacts system level performance parameters including the height of the useable aperture, spatial
and spectral resolving power, optical throughput efficiency, and dynamic range. The efficiency and integrity of both
spatial and spectral input image reproduction within the entire back focal plane area is an often overlooked parameter
leading to unnecessary acceptance of sacrificed system level performance. Examples of input images include the slit
apertured area of a scene captured by a camera lens, a single optical fiber core located within the entrance aperture area,
or a linear array of optical fiber cores stacked along the spatial height of the entrance aperture area. This study evaluates
the spectral and spatial imaging performance of several aberration corrected high reciprocal dispersion retro-reflective
concentric, as well as aberration corrected Offner imaging spectrographs which produce minimal degradation over a
large focal plane. Ray trace images and pixilated area maps demonstrating spatial and spectral reproduction accuracy
over the entire back focal plane are presented.
Keywords: spectral imaging, hyperspectral imaging, multi-channel, fiber sensing, spectrograph, Raman imaging, SORS
1. INTRODUCTION
Hyperspectral imaging is a high spatial resolution spectral imaging technique originally developed for military airborne
and space applications. It is used to capture a wavelength intensity map of a scene with high spatial resolution. The
combination of spectral data and spatial detail enables analysis of color, chemical content, uniformity, quality, and a host
of other spectrophotometric sensing applications. These systems were designed to perform under ambient lighting
conditions, such as available sun light, and therefore required innovative design consideration on sensitivity, efficiency
and dynamic range. Some non-commercial applications of hyperspectral imaging include large area spectral mapping of
mineral deposits after tsunami’s, jungle canopy screening for camouflage detection determined by the disappearance of
the near infrared auto-fluorescent chlorophyll band emitted by live foliage, and friend or foe paint signature
identification. Lately, applications have advanced into commercial and industrial applications including food and
agriculture, anti-counterfeiting, forensics, tissue scanning, cancer detection, biomedical microscopy applications, nano
particle research, hazardous and explosive materials detection, and plastic waste sorting.
Hyperspectral imagers are employed as a scanning “push-broom” imager. For each moment in time, or camera frame
capture, the scene observed by an objective lens is imaged onto a tall slit aperture. The scene which fills the slit aperture
is re-imaged through the spectrometer with the wavelengths dispersed by a grating onto a 2D Focal Plane Array (FPA)
camera such as a CCD. One axis of the FPA (pixel-rows) corresponds to the imaged spatial positions along the slit
height, preferably in a 1:1 relationship. The second axis (spectral; pixel columns) corresponds to spectral wavelength,
which is preferably linearly dispersed and calibrated.
Each 2D image (frame capture), is digitized by the FPA into a 2D data-array corresponding to the field of view imaged
through the slit. While scanning a wide scene, multiple 2D image frame captures are taken while spatially stepping
across the desired scene width, and these individual frames are stacked like a deck of cards to produce a data file
commonly called a hyperspectral data cube. Each pixels value within this hyperspectral data cube represents the
wavelength calibrated spectral intensity of that pixels small field of view on the scene. Figure 1 is a graphical
representation of a hyperspectral data cube.
2. Fig. 1. Hyperspectral data cube (Source: AVIRIS Image Cube)
The resultant three dimensional matrix of data can be analyzed wholly, or interrogated
in several ways such as,
1. Vector: spectra at a position X, Y
2. Vector: X-profile at a particular wavelength
3. Vector: Y-profile at a particular wavelength
4. 2D Field: X, Y intensities at a particular wavelength (like a notch-filtered image of any wavelength)
5. Processed into pseudo-color rendered pictures identifying regions where the intensities of a certain wavelength
fall within prescribed parameters
6. Processed into pseudo-color rendered pictures identifying regions where a certain spectral signature (spectral-
waveform) fall within prescribed parameters
Figure 2 provides an example of the scanning approach in push-broom scanning.
Fig. 2. Push-broom scanning parameters
2. RELAVENCE OF SPECTROGRAPH IMAGING IN MULTI-CHANNEL FIBER SENSING
2.1 Situation
The unique capability of two Headwall Photonics, Inc. hyperspectral imaging spectrometer designs for maintaining
precise spatial and spectral integrity of the image located along an entrance slit height ranging from 8 - 18 mm,
corresponds to the use of large quantities of discreet optical fibers closely spaced in a linear array along the entrance slit
aperture. Spatial and spectral imaging precision minimizes cross talk between each fiber channel, as well as spectral
contamination between each spectral channel, resulting in the ability to maximize the number of discrete optical fibers
which collect spectral data from a multitude of locations simultaneously.
3. The quality of both the spectral and spatial input image reproduction at the spectrograph exit focal plane is an often
overlooked parameter when selecting an optimized spectrometer design to integrate within a multi-channel fiber optic
sensing system. There are various instrument design approaches used for this today, including rack mounting a compact
Czerny-Turner f/4 type master spectrometer with several slave optic/detector spectrometer channels operating in a
parallel or sequential multiplexed mode, use of a research grade Czerny-Turner imaging (torroidal mirror image
compensation) f/4+ spectrometer with a linear array of fiber channels aligned along the entrance slit aperture, as well as
use of axial transmissive spectrograph f/1.8+ designs incorporating a series of focusing and collimating lenses along with
a planar reflective diffraction grating or a transmissive prism-grating-prism assembly.
Since most optical fiber used today in multi-channel applications is made of fused silica with an N.A. of 0.22, systems
faster than f/2.3 do not provide much benefit. Although, one should consider the throughput efficiency comparison
between an f/2.3 versus an f/4 design, as the f/2.3 will process 300% more light provided from the optical fiber. This
results in significantly increased measurement speed and reduced electronic noise.
2.2 What is meant by “Spectral Image” within a Spectrograph
Relating to fiber optic sensing, an example of a spectrometer input image is an individual fiber core that is positioned at the
entrance slit or focal plane. Ideally, one would like to have the shape of this image remain constant after it has been spectrally
dispersed and refocused to an array detector aligned to the back focal plane. When viewing a broadband dispersed spectra, it
is difficult to visualize a discreet “spectral image” of the fiber core at one wavelength, though in fact there are a continuum of
images forming what appears to be a line. One discreet “spectral image” of the fiber core is quantifiable when observing
monochromatic spectra. Illumination by an appropriate atomic emission source is an excellent method for this, as the
extremely narrow spectral lines represent the reimaged shape of the fiber core for that discreet wavelength. Evaluating the
shape and position of these spectral images across the full width of the detector array demonstrates how accurately the
fractional rays at different wavelength positions are focused on their intended pixel locations, and how much wavelength
corruption may occur when distorted rays fall upon unintended pixel locations.
The ray trace images shown in Figure 3 provide conceptual examples of nominal spectral image distortion. Image A
represents a theoretical 50 µm dia. image of uniform intensity at a specific wavelength. At varoius spatial positions over a
focal plane, one would like to maintain this shape, or the shape observed in Image B as well as possible. Although, if a
spectrograph design perscription is not optimized, aberrations distort the size and shape of the spectral image causing rays
intended for that wavelength and spatial position to fall on adjacent locations, thereby corrupting the spectral purity of the
measured results. Images C and D provide examples of emerging image distortions, and are minimal in relation to the extent
they can degrade in commonly accepted “Research Grade” spectrograph designs. As the data we collected demonstrates, the
Raman Explorer does an exceptional job at maintaining high spatial and spectral integrity similar to Image B over the entire
focal plane.
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Image A Image B Image C Image D
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Fig. 3. Conceptual ray trace example of spectral image distortion
4. 2.3 Examples of typical Spectrograph design distortions
2.3.1 Czerny-Turner
Fig. 4
Figure 4 shows an image taken from a 150 mm focal length Czerny-Turner imaging spectrograph which used a torroidal
mirror for image correction. Spectral bandwidth is approximately 2000 cm-1 from a 532 nm laser. Two adjacent 50 µm
fibers which are separated by the combined 20 µm of cladding and buffer layer were isolated within an array. Note the
spatial broadening of the images as wavelength increases left to right. This broadening will cause inaccurate fractional
ray blur on adjacent pixels in both the spectral and spatial domains, and contaminate spectral and optical throughput
purity.
2.3.2 Single Element Aberration Corrected Concave Grating
Fig. 5
Figure 5 shows an image taken from a single element aberration corrected concave grating spectrograph. Several live
50 µm core fibers, seperated by five dead fibers each were illuminated with white light. This illustration is a good
example of “keystone”, where you can notice the center fiber image disperse parallel to array rows and the closest fiber
image neighbors. Although, looking closely, you can see that as the image position moves away from the central sweet
spot of the entrance slit, the dispersed images become non-parallel. Ultimately, this limits the usable number of
individual fiber channels, and can increase noise during readout. The total hieght of this image was 2.8 mm.
2.3.3 Axial Transmissive
A
B
Fig. 6[1]
The top image in Figure 6 shows the resulting curvature of a straight line entrance slit through an axial transmissive
spectrograph. The entrance slit was illuminated by an atomic emission source. This is a well understood result of short
focal length high numerical aperture spectrograph designs which employ planar gratings. An aberration such as this
decreases spectral resolving power, potential signal to noise performance, and creates a challenge with wavelength
calibration. Integrators of this type of spectrograph design restrict the input image height to compensate for this
5. performance issue, resulting in sacrificed signal capture. Others, as demonstrated in the lower image in Figure 6 have
compensated for this aberration by laser drilling a custom entrance aperture in the reverse orientation of the parabolic
shaped aberrated displacement.
The typical axial transmissive prism-grating-prism (PGP) spectrograph design requires two high quality triplet lenses,
one to collimate the light to the PGP element, and the second to focus the dispersed light to the detector. These complex
lens designs are necessary to minimize several common aberrations. There is however a cost to performance for this
correction. Use of refractive optics over a broad spectral bandwidth results in a loss of resolution due to chromatic
aberrations. When a beam of white light hits a lens parallel to the optical axis, the light is refracted differently according
to wavelength. The focal point of short wavelength rays is closer to the lens compared to the focal point of longer
wavelength light. This is referred to as longitudinal chromatic aberration. The color dispersion can be minimized through
the use of compound objectives, one with a high refractive index, and the other with a low refractive index, although
optimizing this over a broad wavelength band is difficult. To minimize this effect, the multi-element lenses are
constructed using several different glass materials, each having a different refractive index. The dissimilar refractive
index of each bonded surface can not be matched by an epoxy, resulting is reflective scattering and losses. Oftentimes,
impurities are trapped at the bonding surface layers which can cause additional scattering or non-uniform spectral
absorption over the surface area. All air to glass interfaces require an anti-reflective optical coating. Without this coating,
losses per surface can reach 4 – 10%. These optical coatings are required to cover a very broad range especially in the
case of the SWIR sensor (900 – 2500 nm). Over such a broad range, multiple coating layers are required, the result of
which can cause a non-uniform transmission intensity, as well as additional impurities which can cause scatter. Optical
anti-reflection coatings only reduce reflections, they do not totally eliminate reflections. Typical performance for broad-
band anti-reflective coatings are 0.5 – 1.0 % residual reflectance. The remainder is subject to create ghost and scattering
affects. Additionally, each glass material has dissimilar expansion and shifts in refractive index with changes in
temperature.
Vignetting is also an important consideration one must fully analyze and understand within any design. In a PGP design,
vignetting may occur when lens mounts block the oblique beams causing the edges along the image plane to be
incompletely filled with the otherwise available light. This results in the reduction of illumination of the outer parts of
the images’ field of view. Vignetting may be minimized by increasing the aperture of the lenses, although this also
increases size, weight, optical scattering, and cost.
Fig. 7[2]. Vignetting and throughput comparison
An independent throughput comparison of an axial-transmissive spectrograph (Kaiser Holospec™) versus an aberration
corrected high reciprocal dispersion retro-reflective concentric spectrograph (Headwall Raman Explorer™) performed at
Vanderbilt University shows broadband quartz tungsten halogen lamp spectrum measured with both spectrographs
(normalized to maximum intensity). As displayed in Figure 7, throughput of the HS is significantly wavelength
dependent compared to the RE. To determine if the throughput degradation was caused by vignetting, the aperture stop
6. of the internal collimating lens in the axial-transmissive design was adjusted to f/5.6, thereby restricting the light path to
the central area of the spectrograph optics. This resulting increase in efficiency at both short and long wavelength
extremes is attributed to vignetting, with the residual losses attributed to differences in diffraction efficiency between the
transmissive and reflective diffraction gratings used in each instrument design.
3. ADVANCED HYPERSPECTRAL IMAGING SPECTROMETERS
Innovative spectrometer designs originally directed towards hyperspectral imaging techniques have enabled high
performance measurement capabilities for a range of multi-channel optical fiber sensors. The following data will
demonstrate recent advancements of several highly efficient hyperspectral imaging spectrometer designs that provide
precise spectral data simultaneously from high throughput multi-channel fiber optic collection.
3.1 Retro-reflective concentric imaging performance for multi-channel fiber imaging
The Headwall Photonics Raman Explorer™ spectrometer designs emphasize angstrom level spectral resolution over a
relatively moderate full spectral bandwidth. The dispersed back focal plane is accurately reimaged over a 26 mm spectral
width, and an 8 mm tall spatial height. Therefore, in multi-channel optical fiber sensing applications, the available linear
height to stack individual fiber channels is up to a maximum of 8 mm, or approximately one hundred thirty 50 µm core
fibers having 10 µm of cladding.
We have performed an evaluation of fine spectral and spatial imaging resolution capabilities and signal throughput
characteristics of our Raman Explorer 785 (785 – 975 nm) f/2.4 spectrograph over the area of an Andor Newton camera
which included a 2048 x 512 array of 13.5 µm square pixels. This evaluation was originally performed using a 1024 x
256 array of 24 µm square pixels, although the resulting horizontal, vertical, and FWHM imaging was pixel limited.
The following is a summary of the 2048 x 512 array results.
To enable imaging of narrow spectral lines, we aligned a test fiber assembly to the entrance aperture. As shown in Figure
8, the test fiber assembly consists of an array of 19 live 50/60/70 µm fibers each separated by 5 dead fibers.
Raman Explorer™
Large area precision focal plane
Fig. 8. Test fiber assembly configuration
This fiber assembly allows us to place live 50 µm core fiber images over 6.5 mm of the available 6.9 mm CCD array
height at 360 µm center to center distances. Neon and Argon atomic line sources were used to illuminate spectral lines
(images) across the full spectral bandwidth of the CCD, then used the following method to capture meaninful spatial and
spectral data points:
1. Focused the fiber images and adjusted the light source intensity and camera integration time to just reach, but stay
within saturation limits of brightest line. We then set integration time so that readout smear between channels was
7. minimized, set background subtraction, and captured and stored the image.
2. Same conditions as above, except placing a 10 µm slit over the ferrule face. Take and store image.
In order to provide a baseline illumination for comparison of throughput vs. integration time, an argon pen lamp was
inserted into a holder and adjusted so that the 794.82 nm line saturated a pixel within any of the available fiber
input/image channels in approximately 0.80 sec. The lamp was then secured in this position.
Using proprietary image test and alignment analysis software developed by Headwall (Figure 9), individual pixel A/D
counts were summed in spatial and spectral direction for each fiber image under test. The SUM is divided by the MAX
SUM and multiplied by 216 (16 bit) to simulate an integration time which meets the saturation point of the register in a
binning application. The pixel A/D count of each fiber image under test was divided by the maximum A/D count within
that image and shown in a scale from 1 to 100 and color coded to depict image performance. The spatial and spectral
imaging resolution was plotted and the FHWM is measured from the plots and reported.
Fig. 9. Headwall Image 9 software
Results of nine 50 µm fiber image positions are shown in Table 1. Three fiber positions along the spatial axis (1, 10, and
19) were selected to demonstrate imaging performance at the top, middle and bottom of the available spatial height, and
atomic line wavelength positions 794.82 nm, 842.48 nm, and 965.78 nm were selected along the spectral axis to
demonstrate spectral extremes. The color coded pixel maps display the individual pixels’ relative intensity and spatial
area which covers >/= 50% (FWHM) of the hottest pixel value at near saturation level for that wavelength. Each square
in the nine pixelated intensity maps shown represents one pixel, and therefore a perfect FWHM image of a 50 µm core
fiber would fill a 4 x 4 pixel area. The horizontal spatial position across the full spectral bandwidth (keystone), and
vertical spectral position along the full spatial height of the fiber array (smile), are held within 1 pixel deviation, leading
to optimal fiber stacking, wavelength resolution, and calibration accuracy.
9. 3.2 Hyperspec™ aberration corrected concentric imaging performance for multi-channel fiber imaging
Headwall Photonics latest developments include high efficiency Hyperspec™ NIR (900 – 1700 nm) and SWIR (1000 –
2500 nm) spectrometer designs which emphasize spatial field of view and high efficiency, with good spectral resolution
over a relatively wide spectral bandwidth. For application reference, full spectral bandwidths covering 200 – 400 nm,
330 – 825 nm, 380 – 825 nm, 400 – 1000 nm, 600 – 1600 nm, 900 – 1700 nm, and 1000 – 2500 nm are designed.
The patented Hyperspec™ is an all reflective aberration corrected Offner imaging spectrograph design which produce
minimal spatial and spectral degradation over a large focal plane. Proprietary developments have now enabled
differentiated peak efficiencies in the 90% range (Fig. 10) for high throughput signal processing, as well as
athermalization for measurement stability. The Hyperspec is also designed for optimal performance based upon the
telecentric entrance pupil formed by an optical fiber.
This evaluation provides performance data of the latest high efficiency Hyperspec™ HE-NIR model. The dispersed back
focal plane is accurately reimaged over an 18 mm tall spatial height, and a 4 mm spectral width. Therefore, in multi-
channel optical fiber sensing applications, the available linear height to stack individual fiber channels is up to a
maximum of 18 mm, or approximately three hundred 50 µm core fibers having 10 µm of cladding.
NIR High Efficiency Modeled and Measured Grating Efficiency
100%
90%
80%
70%
Efficiency (%)
60%
50%
40%
Measured
30%
Modeled
20%
10%
0%
500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
Wavelength (nm)
High Efficiency Hyperspec™ NIR Fig. 10. HE-NIR 900 – 1700 nm modeled and as built diffraction efficiency
Fine spectral and spatial imaging resolution capabilities and signal efficiency characteristics of the Hyperspec™ HE-NIR
f/2.4 spectrograph was collected using an integrated Goodrich SU640SDWH-1.7RT InGaAs camera with a 640 x 512
array of 25 µm square pixels.
As displayed in the nine point pixelated table (Table 1), it is critical to maintain tight control of an input image when it is
refocused at intended wavelength position on the back focal plane. One measure of this is referred to as ensquared
energy. The procedure used for measurement of ensquared energy on the HE-NIR included installing a spectrograph
entrance aperture consisting of a linear array of 25 µm pinholes, thereby creating an entrance image matched to the 25
µm pixel pitch on the detector array. The illumination source was an Agilent Technologies 1550 nm tunable laser source.
10. Table 2. Pixel intensity map
507 2558 484
895 12591 1527
303 1919 831
Fig. 11. 3 x 3, 25 µm pixels
Figure 11 is an enlarged pixel intensity display off the array. Within the central 3 x 3 pixel area, 65% of the light energy
launched from the 25 µm pinhole at the entrance aperture is contained within one 25 µm pixel point. Table 2 shows the
relative intensity of each pixel. The spatial FWHM results in 1.1 pixels, and the spectral FWHM results in 1.2 pixels.
Spectral image data at 1310 nm and 1550 nm was collected for fourteen pinhole positions over 16 mm of the spatial
image height. As Figures 12 and 13 show, smile measured ≤ 0.16 pixels (4 µm) for the total 16 mm spatial height,
demonstrating excellent spatial image tracking across the spectral width. This accuracy reduces calibration complexity,
and enables increased spectral resolution if binning multiple fibers along the spatial axis. Data collected for one frame,
no averaging.
HE-G1-127; 1310 nm HE-G1-127; 1550 nm
Spectral Pixel Position vs Position Along Slit
Spectral Pixel Position vs Position Along Slit
347
371.54
346.98
371.52
Spectral Pixel Position (Pixel #)
346.96
Spectral Pixel Position (Pixel #)
371.5
346.94
346.92 371.48
346.9 371.46
346.88
371.44
346.86
371.42
346.84
371.4
346.82
346.8 371.38
0 100 200 300 400 500 600 700 0 100 200 300 400 500 600 700
Position Along Slit (pixel #) Position Along Slit (pixel #)
Fig. 12. 1310 nm smile Fig. 13. 1550 nm smile
This same spectral image data was used for investigation of keystone, or the accuracy of which one spatial input image
tracks along one spectral pixel row throughout the length of the full spectral band width. Negligible keystone distortion
of ≤ 0.04 pixels (1µm) was measured. This level of accuracy minimizes the necessary number of pixels which are binned
for each individual fiber channel, and enables a maximum volume of individual fiber channels to be processed.
4. CONCLUSION
Two advanced hyperspectral imaging spectrograph designs were evaluated to demonstrate their potential benefits when
applied to multi-channel fiber optic spectral sensing applications. One which emphasizes angstrom level spectral
resolution and 8 mm of stackable fiber aperture height, and one which emphasizes up to 18 mm of stackable fiber
aperture height and nanometer spectral resolution. Each of these systems demonstrated exceptional accuracy for 1:1
feature imaging, and pixel limited keystone and smile, which optimizes the ability to process a maximum volume of
individual channels simultaneously. These systems provide up to 90% efficiency and are matched to the numeric
aperture of silica fibers, providing an excellent opportunity for optimizing high throughput measurement results.
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Optics Letters, Volume 26, No. 22, 1782-1784 (2001)
[2] Lieber, C. A., Kanter, E. M. And Mahadevan-Jansen, A., “Comparison of Raman Spectrograph Throughput Using
Two Commercial Systems: Transmissive Versus Reflective”, Applied Spectroscopy, Volume 62, Number 5, 575-
582 (2008)