This document summarizes the design and simulation of a vibration sensor based on optical fibers.
1) The sensor design uses a laser, polarizer, piezoelectric fiber stretcher, and analyzer to detect how vibrations change the polarization state of light traveling through an optical fiber.
2) A mathematical model shows the sensor output is non-linearly related to the excitation frequency due to higher-order terms.
3) The model indicates the amplitude of the 2fexc component provides the best opportunity to directly determine the amplitude of mechanical excitation.
This document proposes a new synthetic aperture radar (SAR) configuration called cooperative multimonostatic (CMM) SAR that consists of multiple coordinated monostatic SAR platforms. CMM SAR is designed to improve resolution over conventional monostatic SAR by coordinating the flight paths and frequency bands of the individual platforms. Three proposed CMM SAR configurations are evaluated and shown to provide substantial improvements in resolution compared to monostatic SAR operating with the same overall bandwidth. One configuration is especially promising due to gains in both performance and simplicity of implementation.
This document summarizes a research paper on detecting intruders in a wireless sensor network using low-power passive infrared (PIR) sensors. It presents an algorithm that uses the Haar transform and support vector machines to distinguish intruder signatures from clutter signatures in the sensor data. The algorithm was tested through simulations and field experiments, achieving detection rates over 90% while minimizing false alarms. However, limitations were observed when testing in high-clutter summer conditions. An analytical model of intruder signatures suggests that velocity and direction information cannot be extracted from a single sensor but may require a network of spatially distributed sensors.
This document discusses using light sensing with the micro:bit. It begins by explaining light measurement units and light sensing components. It then covers how to sense light levels using the LEDs on the micro:bit by switching them to analog inputs. Two practice exercises are described - an automatic night light that adjusts brightness based on light levels, and a face-changing display that shows different icons when light is blocked from the LEDs.
A Physical Approach to Moving Cast Shadow Detection (ICASSP 2009)Jia-Bin Huang
This document presents a physics-based approach for detecting moving cast shadows in video sequences. It develops a new physical model to characterize the variation in background appearance caused by cast shadows, without making assumptions about the spectral power distributions of light sources and ambient illumination. It uses a Gaussian mixture model to learn and update the shadow model parameters over time in an unsupervised manner. Experimental results on three challenging sequences demonstrate the effectiveness of the proposed method.
A spectrophotometer is an instrument that measures the amount of photons absorbed by a sample after it is passed through its solution.
UV-Visible spectrophotometer uses UV and visible range of electromagnetic radiation spectrum.
This document provides an overview of nonlinear optics and second harmonic generation. It begins with an introduction to lasers and their components. It then discusses symmetry operations in crystals and how centrosymmetric and noncentrosymmetric materials affect nonlinear polarization. Maxwell's equations are presented for linear media. The document introduces nonlinear optics and lists various nonlinear optical effects such as second harmonic generation. It derives the wave equation for nonlinear media and shows how second harmonic generation leads to frequency doubling. Examples of nonlinear crystals used for second harmonic generation are also provided.
Link and Energy Adaptive Design of Sustainable IR-UWB Communications and SensingDong Zhao
The presentation introduces the research on IR-UWB that jointly exploited realtime link analysis with non-deterministic renewable energy characteristics and developed adaptive schemes that can dynamically operate the sensing or communications with better time coverage, energy efficiency, and resistance to battery aging effects, etc.
This document proposes a new synthetic aperture radar (SAR) configuration called cooperative multimonostatic (CMM) SAR that consists of multiple coordinated monostatic SAR platforms. CMM SAR is designed to improve resolution over conventional monostatic SAR by coordinating the flight paths and frequency bands of the individual platforms. Three proposed CMM SAR configurations are evaluated and shown to provide substantial improvements in resolution compared to monostatic SAR operating with the same overall bandwidth. One configuration is especially promising due to gains in both performance and simplicity of implementation.
This document summarizes a research paper on detecting intruders in a wireless sensor network using low-power passive infrared (PIR) sensors. It presents an algorithm that uses the Haar transform and support vector machines to distinguish intruder signatures from clutter signatures in the sensor data. The algorithm was tested through simulations and field experiments, achieving detection rates over 90% while minimizing false alarms. However, limitations were observed when testing in high-clutter summer conditions. An analytical model of intruder signatures suggests that velocity and direction information cannot be extracted from a single sensor but may require a network of spatially distributed sensors.
This document discusses using light sensing with the micro:bit. It begins by explaining light measurement units and light sensing components. It then covers how to sense light levels using the LEDs on the micro:bit by switching them to analog inputs. Two practice exercises are described - an automatic night light that adjusts brightness based on light levels, and a face-changing display that shows different icons when light is blocked from the LEDs.
A Physical Approach to Moving Cast Shadow Detection (ICASSP 2009)Jia-Bin Huang
This document presents a physics-based approach for detecting moving cast shadows in video sequences. It develops a new physical model to characterize the variation in background appearance caused by cast shadows, without making assumptions about the spectral power distributions of light sources and ambient illumination. It uses a Gaussian mixture model to learn and update the shadow model parameters over time in an unsupervised manner. Experimental results on three challenging sequences demonstrate the effectiveness of the proposed method.
A spectrophotometer is an instrument that measures the amount of photons absorbed by a sample after it is passed through its solution.
UV-Visible spectrophotometer uses UV and visible range of electromagnetic radiation spectrum.
This document provides an overview of nonlinear optics and second harmonic generation. It begins with an introduction to lasers and their components. It then discusses symmetry operations in crystals and how centrosymmetric and noncentrosymmetric materials affect nonlinear polarization. Maxwell's equations are presented for linear media. The document introduces nonlinear optics and lists various nonlinear optical effects such as second harmonic generation. It derives the wave equation for nonlinear media and shows how second harmonic generation leads to frequency doubling. Examples of nonlinear crystals used for second harmonic generation are also provided.
Link and Energy Adaptive Design of Sustainable IR-UWB Communications and SensingDong Zhao
The presentation introduces the research on IR-UWB that jointly exploited realtime link analysis with non-deterministic renewable energy characteristics and developed adaptive schemes that can dynamically operate the sensing or communications with better time coverage, energy efficiency, and resistance to battery aging effects, etc.
This document compares and contrasts linear and nonlinear optics. In linear optics, light propagates through a medium without changing frequency, while in nonlinear optics the medium's response depends on light intensity. Nonlinear optics involves effects where the induced polarization in a medium does not linearly depend on the electric field of the light. This allows frequency conversion via processes like second harmonic generation and sum frequency generation. Materials can exhibit a nonlinear refractive index, leading to self-focusing or defocusing of high intensity light beams. Nonlinear optical effects enable applications like frequency conversion, optical limiting, and all-optical signal processing.
Long distance communication using localized optical soliton via entangled photonUniversity of Malaya (UM)
This document summarizes research on using localized optical solitons generated by microring resonators for long distance communication via entangled photons. A system of microring resonators is presented that can generate broadband spectra through temporal and spatial soliton pulses trapped within the rings. Simulations show localized solitons with femtosecond and picosecond widths can be generated. The soliton pulses could then be used to implement continuous-variable quantum key distribution over long distances by encoding entangled photon pairs across different time slots. This research proposes a way to securely transmit information for communication networks using nonlinear photonics and quantum optics techniques.
This document discusses ultraviolet-visible spectroscopy (UV-Vis), which uses light in the visible and near-UV/near-infrared ranges to analyze molecular transitions. It describes the basic components and principles of UV-Vis spectrophotometers, including their light sources, dispersion devices, sample areas, and detectors. Different brands of UV spectrophotometers are listed, and the document outlines the principles, components, accessories, and maintenance of UV-Vis spectroscopy.
Nonlinear optics involves intense light interacting with matter to change the light's properties. This allows generating new frequencies of light from the input light. Second harmonic generation produces light with twice the frequency by combining two photons. High harmonic generation using intense lasers can generate coherent x-rays. Phase matching is important for high conversion efficiency in nonlinear optical processes. Applications include optical switching, data storage, and generating coherent x-rays for attosecond science.
Spectroscopy involves using electromagnetic radiation to study chemical compounds and the interactions between radiation wavelengths and compounds. Different regions of the electromagnetic spectrum (e.g. ultraviolet, infrared, nuclear magnetic resonance) cause energy transitions in compounds through absorption. The energy and wavelength of absorbed radiation is directly related and allows compounds to be identified based on their unique absorption spectra. Spectrometers and fluorometers are instruments used to measure absorption and fluorescent emission spectra, revealing information about molecular structure and properties.
This document discusses semiconductors and their properties. It begins by defining semiconductors as materials with resistivity between insulators and conductors. It then discusses several key points:
- Semiconductor resistivity is sensitive to temperature, illumination, magnetic fields, and impurities.
- Common semiconductor materials include silicon, germanium, and various compound semiconductors.
- Semiconductors have a small bandgap that allows slight conductivity through thermal excitation of electrons.
- The bandgap can be measured through optical absorption and determines many material properties.
- Carrier concentrations in intrinsic and extrinsic semiconductors are described through concepts like the density of states, Fer
The document discusses using a micro:bit for light sensing applications. It explains how the micro:bit can sense light levels using its LEDs as photodiodes. When an LED pin is set as an analog input, the voltage measured corresponds to the ambient light level. Two example projects are described - an automatic night light that adjusts its brightness based on light levels, and a magic face panel display that changes expressions when the LED is covered and uncovered.
1994 restoration of noisy scanning tunneling microscope imagespmloscholte
This document compares and improves several implementations of the Wiener filter to remove noise from Scanning Tunneling Microscope (STM) images. It finds that the implementation by Weisman et al. using the noise model of Stoll et al. provides the best performance on both simulated and real STM images. It tests the filters on simulated graphite images with added 1/f noise and finds the modified Weisman filter performs significantly better than other implementations on a real STM graphite image due to deviations from the 1/f noise model.
This document summarizes the first experimental observation of second harmonic generation (SHG). The experiment used a ruby laser to generate visible red light that was passed through a quartz crystal, producing a small amount of visible blue light, demonstrating the nonlinear optical effect of SHG. While the SHG output was very small, on the order of 1011 photons, it validated the theoretical prediction that the intensity of the harmonic frequency generated would depend on the intensity of the fundamental frequency. This pioneering work also highlighted limitations due to the short coherence length of the ruby laser and lack of phase matching used.
This summary provides the key points about an approach being investigated to enable all-optical switching and logic elements using the Zeno effect:
1) The approach aims to overcome challenges with existing all-optical switching technologies like the need for intense optical fields and high power dissipation.
2) It involves using a high quality factor microresonator containing an optical medium with high two-photon absorption to enhance nonlinear effects while minimizing losses via the Zeno effect.
3) Theoretical simulations and analysis indicate this approach could allow all-optical switching, logic, and memory functions with extremely low power dissipation if challenges like achieving high enough two-photon absorption rates are addressed.
Bat algorithm is metaheuristic that can be applied for global optimization. It was inspired by the echolocation behaviour of microbats, with varying pulse rates of emission and loudness
This document summarizes a research paper on a surface plasmon resonance (SPR) fiber optic sensor with an enhanced U-shaped design. The researchers modeled how decreasing the bending radius of the U-shaped fiber probe increases the sensitivity of the sensor by up to 25 times compared to a straight fiber probe. They found an optimal bending radius of 1.0 cm provided the best performance by maximizing the interaction between light in the fiber core and surface plasmons excited on the metallic coating. The theoretical analysis considered light propagation in two dimensions within the bent plane and calculated transmitted power through the probe to determine sensitivity based on resonance conditions between incident light and surface plasmons.
Replacing real values with complex values in areas like window functions can lead to new solutions. A complex-valued window function was developed that can be applied to non-coherently sampled waveforms without spectral leakage artifacts. This "extended Fourier transform" works by decomposing the signal into a complex expression, rounding the number of periods to an integer, and applying a "twiddle function" or complex-valued window to change the angular velocity before taking the Fourier transform. More research is needed to fully understand this approach and explore other applications of complex values.
UV-visible spectrophotometers have five main components: a light source, filters or monochromator, sample compartment, detector, and recorder. Common light sources include tungsten lamps for the visible region and deuterium lamps for the UV region. Filters and monochromators are used to select the wavelength of light. Samples are placed in the sample compartment for analysis. Detectors such as photodiodes, photomultiplier tubes, or barrier layer cells convert light signals to electrical signals. The signals are then recorded to obtain a spectrum.
This document provides an outline and introduction to compactly supported wavelets and their application in solving partial differential equations (PDEs). It begins with background on the development of wavelet analysis from Fourier analysis. It then discusses compactly supported wavelets, their properties like smoothness and finite support. It also briefly introduces multivariable wavelets and their use in higher dimensions before concluding with references. The overall purpose is to introduce wavelet methods for solving PDEs using compactly supported wavelets.
Kalawati patil be e&tc oc module 5 part ikalawatimpatil
The document discusses optical detectors and photodetectors. It covers:
1. The working principle of photodetectors which involves the absorption of photons generating electron-hole pairs.
2. Characteristics of different photodetector types including p-i-n diodes and avalanche photodiodes (APDs).
3. Performance parameters such as quantum efficiency, responsivity, and dark current.
4. The document provides examples and calculations to illustrate these concepts.
This document provides an introduction to the field of nanophotonics. It defines nanophotonics as the science and engineering of light-matter interactions that take place on wavelength and subwavelength scales. Examples of nanophotonics in nature are discussed. The foundations of nanophotonics are explored, including similarities between the propagation of photons and electrons. Computational methods for modeling nanophotonic structures like finite difference time domain are also summarized. The effects of quantum confinement on the optical properties of nanostructures are described.
This document provides an overview of ultraviolet-visible (UV-Vis) spectrophotometry. It discusses the basic principles, including how electrons are excited by specific wavelengths of light and how this relates to absorption. Instrumentation for UV-Vis spectrophotometers is described, including how it measures absorbance using a reference and sample cell. The Beer-Lambert law explains how absorbance is proportional to concentration. Calibration procedures and modern applications in fields like clinical chemistry, environmental analysis and teaching are also summarized.
Detection of gamma radiation is used to study properties of atomic nuclei. Two common detectors are scintillation detectors and semiconductor detectors. Scintillation detectors use scintillation materials that emit visible light when struck by gamma rays, while semiconductor detectors use depletion regions in germanium crystals. Both detectors require amplification and signal processing electronics to analyze the energy deposited by gamma rays. Key measurements involve determining the energy spectrum of gamma ray sources and identifying peaks and edges that reveal information about nuclear properties and interactions.
Optical interferometery to detect sound waves as an analogue for gravitationa...Thomas Actn
This document describes an experiment using a Michelson interferometer to detect sound waves as an analogue for gravitational waves. A tuning fork resonating at 440Hz and a piezoelectric crystal were used to generate sound waves near one arm of the interferometer. An Arduino and oscilloscope measured the resulting interference patterns. The Arduino detected the tuning fork frequency accurately but the oscilloscope only detected around half the frequency due to its limited sampling. Multiple constituent frequencies were detected from hand claps, mimicking bursts from supernovae. While the setup could detect these 'fake' gravitational waves, its low sampling rate limited the detectable frequency window.
This document describes a new ultrafast Diffuse Optical Tomography (DOT) technique developed for real-time in vivo brain imaging of songbirds. The technique uses an amplified ultrafast laser and single-shot streak camera to measure the time of flight of photons through brain tissue. This allows for a 3D reconstruction of brain activity from space and time sampling of the reflectance signal. Preliminary results show the brain tissue response to hypercapnia stimulations can be detected.
This document compares and contrasts linear and nonlinear optics. In linear optics, light propagates through a medium without changing frequency, while in nonlinear optics the medium's response depends on light intensity. Nonlinear optics involves effects where the induced polarization in a medium does not linearly depend on the electric field of the light. This allows frequency conversion via processes like second harmonic generation and sum frequency generation. Materials can exhibit a nonlinear refractive index, leading to self-focusing or defocusing of high intensity light beams. Nonlinear optical effects enable applications like frequency conversion, optical limiting, and all-optical signal processing.
Long distance communication using localized optical soliton via entangled photonUniversity of Malaya (UM)
This document summarizes research on using localized optical solitons generated by microring resonators for long distance communication via entangled photons. A system of microring resonators is presented that can generate broadband spectra through temporal and spatial soliton pulses trapped within the rings. Simulations show localized solitons with femtosecond and picosecond widths can be generated. The soliton pulses could then be used to implement continuous-variable quantum key distribution over long distances by encoding entangled photon pairs across different time slots. This research proposes a way to securely transmit information for communication networks using nonlinear photonics and quantum optics techniques.
This document discusses ultraviolet-visible spectroscopy (UV-Vis), which uses light in the visible and near-UV/near-infrared ranges to analyze molecular transitions. It describes the basic components and principles of UV-Vis spectrophotometers, including their light sources, dispersion devices, sample areas, and detectors. Different brands of UV spectrophotometers are listed, and the document outlines the principles, components, accessories, and maintenance of UV-Vis spectroscopy.
Nonlinear optics involves intense light interacting with matter to change the light's properties. This allows generating new frequencies of light from the input light. Second harmonic generation produces light with twice the frequency by combining two photons. High harmonic generation using intense lasers can generate coherent x-rays. Phase matching is important for high conversion efficiency in nonlinear optical processes. Applications include optical switching, data storage, and generating coherent x-rays for attosecond science.
Spectroscopy involves using electromagnetic radiation to study chemical compounds and the interactions between radiation wavelengths and compounds. Different regions of the electromagnetic spectrum (e.g. ultraviolet, infrared, nuclear magnetic resonance) cause energy transitions in compounds through absorption. The energy and wavelength of absorbed radiation is directly related and allows compounds to be identified based on their unique absorption spectra. Spectrometers and fluorometers are instruments used to measure absorption and fluorescent emission spectra, revealing information about molecular structure and properties.
This document discusses semiconductors and their properties. It begins by defining semiconductors as materials with resistivity between insulators and conductors. It then discusses several key points:
- Semiconductor resistivity is sensitive to temperature, illumination, magnetic fields, and impurities.
- Common semiconductor materials include silicon, germanium, and various compound semiconductors.
- Semiconductors have a small bandgap that allows slight conductivity through thermal excitation of electrons.
- The bandgap can be measured through optical absorption and determines many material properties.
- Carrier concentrations in intrinsic and extrinsic semiconductors are described through concepts like the density of states, Fer
The document discusses using a micro:bit for light sensing applications. It explains how the micro:bit can sense light levels using its LEDs as photodiodes. When an LED pin is set as an analog input, the voltage measured corresponds to the ambient light level. Two example projects are described - an automatic night light that adjusts its brightness based on light levels, and a magic face panel display that changes expressions when the LED is covered and uncovered.
1994 restoration of noisy scanning tunneling microscope imagespmloscholte
This document compares and improves several implementations of the Wiener filter to remove noise from Scanning Tunneling Microscope (STM) images. It finds that the implementation by Weisman et al. using the noise model of Stoll et al. provides the best performance on both simulated and real STM images. It tests the filters on simulated graphite images with added 1/f noise and finds the modified Weisman filter performs significantly better than other implementations on a real STM graphite image due to deviations from the 1/f noise model.
This document summarizes the first experimental observation of second harmonic generation (SHG). The experiment used a ruby laser to generate visible red light that was passed through a quartz crystal, producing a small amount of visible blue light, demonstrating the nonlinear optical effect of SHG. While the SHG output was very small, on the order of 1011 photons, it validated the theoretical prediction that the intensity of the harmonic frequency generated would depend on the intensity of the fundamental frequency. This pioneering work also highlighted limitations due to the short coherence length of the ruby laser and lack of phase matching used.
This summary provides the key points about an approach being investigated to enable all-optical switching and logic elements using the Zeno effect:
1) The approach aims to overcome challenges with existing all-optical switching technologies like the need for intense optical fields and high power dissipation.
2) It involves using a high quality factor microresonator containing an optical medium with high two-photon absorption to enhance nonlinear effects while minimizing losses via the Zeno effect.
3) Theoretical simulations and analysis indicate this approach could allow all-optical switching, logic, and memory functions with extremely low power dissipation if challenges like achieving high enough two-photon absorption rates are addressed.
Bat algorithm is metaheuristic that can be applied for global optimization. It was inspired by the echolocation behaviour of microbats, with varying pulse rates of emission and loudness
This document summarizes a research paper on a surface plasmon resonance (SPR) fiber optic sensor with an enhanced U-shaped design. The researchers modeled how decreasing the bending radius of the U-shaped fiber probe increases the sensitivity of the sensor by up to 25 times compared to a straight fiber probe. They found an optimal bending radius of 1.0 cm provided the best performance by maximizing the interaction between light in the fiber core and surface plasmons excited on the metallic coating. The theoretical analysis considered light propagation in two dimensions within the bent plane and calculated transmitted power through the probe to determine sensitivity based on resonance conditions between incident light and surface plasmons.
Replacing real values with complex values in areas like window functions can lead to new solutions. A complex-valued window function was developed that can be applied to non-coherently sampled waveforms without spectral leakage artifacts. This "extended Fourier transform" works by decomposing the signal into a complex expression, rounding the number of periods to an integer, and applying a "twiddle function" or complex-valued window to change the angular velocity before taking the Fourier transform. More research is needed to fully understand this approach and explore other applications of complex values.
UV-visible spectrophotometers have five main components: a light source, filters or monochromator, sample compartment, detector, and recorder. Common light sources include tungsten lamps for the visible region and deuterium lamps for the UV region. Filters and monochromators are used to select the wavelength of light. Samples are placed in the sample compartment for analysis. Detectors such as photodiodes, photomultiplier tubes, or barrier layer cells convert light signals to electrical signals. The signals are then recorded to obtain a spectrum.
This document provides an outline and introduction to compactly supported wavelets and their application in solving partial differential equations (PDEs). It begins with background on the development of wavelet analysis from Fourier analysis. It then discusses compactly supported wavelets, their properties like smoothness and finite support. It also briefly introduces multivariable wavelets and their use in higher dimensions before concluding with references. The overall purpose is to introduce wavelet methods for solving PDEs using compactly supported wavelets.
Kalawati patil be e&tc oc module 5 part ikalawatimpatil
The document discusses optical detectors and photodetectors. It covers:
1. The working principle of photodetectors which involves the absorption of photons generating electron-hole pairs.
2. Characteristics of different photodetector types including p-i-n diodes and avalanche photodiodes (APDs).
3. Performance parameters such as quantum efficiency, responsivity, and dark current.
4. The document provides examples and calculations to illustrate these concepts.
This document provides an introduction to the field of nanophotonics. It defines nanophotonics as the science and engineering of light-matter interactions that take place on wavelength and subwavelength scales. Examples of nanophotonics in nature are discussed. The foundations of nanophotonics are explored, including similarities between the propagation of photons and electrons. Computational methods for modeling nanophotonic structures like finite difference time domain are also summarized. The effects of quantum confinement on the optical properties of nanostructures are described.
This document provides an overview of ultraviolet-visible (UV-Vis) spectrophotometry. It discusses the basic principles, including how electrons are excited by specific wavelengths of light and how this relates to absorption. Instrumentation for UV-Vis spectrophotometers is described, including how it measures absorbance using a reference and sample cell. The Beer-Lambert law explains how absorbance is proportional to concentration. Calibration procedures and modern applications in fields like clinical chemistry, environmental analysis and teaching are also summarized.
Detection of gamma radiation is used to study properties of atomic nuclei. Two common detectors are scintillation detectors and semiconductor detectors. Scintillation detectors use scintillation materials that emit visible light when struck by gamma rays, while semiconductor detectors use depletion regions in germanium crystals. Both detectors require amplification and signal processing electronics to analyze the energy deposited by gamma rays. Key measurements involve determining the energy spectrum of gamma ray sources and identifying peaks and edges that reveal information about nuclear properties and interactions.
Optical interferometery to detect sound waves as an analogue for gravitationa...Thomas Actn
This document describes an experiment using a Michelson interferometer to detect sound waves as an analogue for gravitational waves. A tuning fork resonating at 440Hz and a piezoelectric crystal were used to generate sound waves near one arm of the interferometer. An Arduino and oscilloscope measured the resulting interference patterns. The Arduino detected the tuning fork frequency accurately but the oscilloscope only detected around half the frequency due to its limited sampling. Multiple constituent frequencies were detected from hand claps, mimicking bursts from supernovae. While the setup could detect these 'fake' gravitational waves, its low sampling rate limited the detectable frequency window.
This document describes a new ultrafast Diffuse Optical Tomography (DOT) technique developed for real-time in vivo brain imaging of songbirds. The technique uses an amplified ultrafast laser and single-shot streak camera to measure the time of flight of photons through brain tissue. This allows for a 3D reconstruction of brain activity from space and time sampling of the reflectance signal. Preliminary results show the brain tissue response to hypercapnia stimulations can be detected.
This document describes a dual mode fiber optic SPR chemical microsensor that utilizes surface plasmon resonance (SPR) to detect chemicals surrounding an optical fiber. The sensor consists of a multimode fiber coated with gold to support SPR. Measurements in the visible and near-infrared regions show that the near-infrared spectrum provides a more sensitive detection mechanism. Theoretical calculations and experimental results demonstrate that the near-infrared SPR spectrum has a larger and sharper resonant peak compared to the visible spectrum. This dual mode sensor design allows for more sensitive chemical detection applications.
Nuclear magnetic resonance spectroscopy involves subjecting atomic nuclei to magnetic fields and measuring the electromagnetic radiation absorbed and emitted. Fourier transform NMR provides increased sensitivity by combining multiple free induction decay signals measured in the time domain. A Fourier transform converts these signals to an NMR spectrum in the frequency domain. The Michelson interferometer induces interference of light waves by splitting and recombining beams that traveled different path lengths, allowing observation of interference patterns related to the wavelength of light.
This document discusses Fourier transform infrared spectroscopy (FTIR) and its application in analyzing polydimethylsiloxane (PDMS). It begins with an introduction to FTIR, describing how it uses Fourier transforms to measure infrared absorption spectra. It then covers the basic concepts of FTIR including Michelson interferometers, Fourier transforms, and advantages over dispersive spectrometers. Applications discussed include chemical reaction analysis and surface functional group analysis. It provides an example using FTIR to analyze the reaction mechanism of photo-defined PDMS.
This document discusses various techniques for measuring key optical fiber parameters. It describes methods for measuring total fiber attenuation using cut-back or substitution techniques. It also outlines approaches for measuring specific loss mechanisms like absorption and scattering loss. Methods covered for other fiber characteristics include dispersion measurement in time or frequency domains, refractive index profiling using interferometry or near-field scanning, numerical aperture determination, and diameter measurement of the fiber core and outer dimensions.
1. The experiment aims to verify Malus' law, which states that the intensity of light transmitted through a polarizer-analyzer system varies as the cosine squared of the angle between their transmission axes.
2. A laser beam is passed through a polarizer and analyzer, and the transmitted light intensity is measured using a photodetector as the analyzer angle is varied. The measured intensities closely match the theoretical cosine squared relationship.
3. Plots of measured intensity versus both cosine squared of the angle and the theoretical intensities produce straight lines, confirming Malus' law and the proportionality of intensity and the square of the amplitude of transmitted light waves.
The document discusses various techniques for measuring properties of optical fibers, including:
- Attenuation measurement using the cut-back method to determine loss per unit length.
- Absorption and scattering loss measurement using temperature rise calculations and comparing scattered light.
- Dispersion measurement in the time domain using pulse broadening or in the frequency domain using spectral broadening.
- Refractive index profiling using interferometry of fiber slices or near-field scanning of light distributions.
- Numerical aperture determination by measuring far-field emission patterns or trigonometric calculations from patterns.
- Diameter measurement using laser scanning of fiber shadows or analysis of far-field scattering patterns.
svk.ppt final powerrr pointttt presentationsrajece
This document discusses various techniques for measuring properties of optical fibers, including:
- Attenuation measurement using the cut-back method to determine loss per unit length.
- Absorption loss measurement using a temperature measurement setup to separate out absorption contributions.
- Scattering loss measurement using a scattering cell to compare scattered and total power.
- Dispersion measurement using either time domain analysis of broadened pulses or frequency domain analysis of the fiber's transmission spectrum.
- Refractive index profile measurement using interferometry of a fiber slice or near-field scanning of light intensities.
The document presents two oscillation control algorithms for resonant sensors like vibratory gyroscopes. The first algorithm uses automatic gain control and a phase-locked loop to track the resonant frequency while maintaining a specified amplitude. The second algorithm tunes the resonant frequency to a specified value by modifying the resonator dynamics, while also using automatic gain control to regulate the amplitude. Both control systems are analyzed for stability using an averaging method. The algorithms are applied to problems in dual-mass vibratory gyroscopes and general vibratory gyroscopes to demonstrate their effectiveness.
Mode-Locked Erbium Doped Pulse Fiber Laser Using the Kerr EffectKyle McSwain
This document describes an experiment to build a pulsed fiber laser using erbium-doped fiber and the Kerr effect. The researchers were able to generate ≤400ps pulses within a 12 meter ring cavity at a peak spacing of about 60 ns. They believe this places the pulses in either the soliton or stretched pulse regime. The laser utilizes an artificial saturable absorber composed of polarizing elements to generate pulses in the 1550 nm spectrum through passive mode-locking via the Kerr effect and self-phase and self-amplitude modulation.
This document describes the calibration of an optical tweezer apparatus used to trap and manipulate polystyrene microbeads. Preliminary measurements found the trap stiffness to be 0.00591 ± 0.00139 pN/nm in the x direction and 0.00693 ± 0.00068 pN/nm in the y direction. However, the accuracy of these results is questionable due to unresolved issues with the apparatus. Additionally, the effect of surface proximity on backscattered laser light was investigated. Once calibrated, the apparatus can measure piconewton scale forces and will be used for experiments involving confined DNA molecules.
1) The document discusses methods for improving the sensitivity of electronic support measure (ESM) receivers through post-integration processing using autocorrelation and cross-correlation.
2) Autocorrelation processing takes advantage of the periodic nature of radar signals to improve detection of high repetition frequency signals. It provides a sensitivity gain that depends on the integration window and pulse repetition interval.
3) Three estimators are examined for extracting radar parameters: a straightforward method, interpolation method, and maximum likelihood method, with the maximum likelihood method providing the best accuracy.
Aggelos Katsaggelos, Professor and AT&T Chair, Northwestern University, Department of Electrical Engineering & Computer Science (IEEE/ SPIE Fellow, IEEE SPS DL), Sparse and Redundant Representations: Theory and Applications
The document discusses Fourier transform infrared (FTIR) spectroscopy. It explains that FTIR spectroscopy uses a Michelson interferometer to obtain an infrared spectrum of a sample. The interferometer collects an interferogram that is then Fourier transformed to obtain the spectrum. FTIR spectroscopy provides advantages over dispersive infrared spectroscopy like speed, sensitivity, and mechanical simplicity. It finds applications in identifying organic and inorganic compounds, mixtures, and gases, liquids, and solids.
The document discusses Fourier transform infrared spectroscopy (FTIR). It begins with an overview of spectroscopy and a history of FTIR development. It then explains that FTIR uses a Fourier transform algorithm to convert interferograms from a Michelson interferometer into infrared spectra. The document describes the basic components of an FTIR instrument including its IR radiation source, Michelson interferometer, and detectors. It provides details on how FTIR is able to collect spectral data using infrared light and a Fourier transform. The document concludes with sections on applications and sample preparation methods for FTIR.
1. Microwave diagnostics techniques such as interferometry, reflectometry, scattering and electron cyclotron emission (ECE) have been powerful tools for diagnosing magnetically confined plasmas.
2. Recent advances in electronics and computer technology have enabled the development of advanced microwave diagnostic systems that can measure 2D and 3D profiles of plasma density, temperature, and fluctuations.
3. Key microwave diagnostic techniques discussed in the document are interferometry, reflectometry, and ECE. Interferometry measures line integrated density, reflectometry measures local density, and ECE measures local electron temperature. These techniques provide important information for understanding issues in plasma physics like stability, waves, and transport.
Low Cost Device to Measure the Thickness of Thin Transparent FilmsIDES Editor
There is often a requirement to fabricate thin glass
plates for prototyping purposes in a research lab. For example
to make a prototype of an optic filter there is a need to fabricate
a number of thin glass plates and in most moderately equipped
optic research laboratory there is facility to etch these glass
plates, but lacks instruments to measure its thickness. Our main
purpose is to design a system which is cost friendly and is
capable of measuring the thickness with a resolution lesser than
1μm.A combination of Michelson interferometer and an
electronic fringe counter makes up this instrument. The
interferometer produces the fringes which can be made to shift
in relation to the thickness of the film to be measured. The
number of fringes shifted is recorded be the counter using which
the thickness can be determined (note: the refractive index of
the plate should be known)
This document describes a method for examining the microstructure of a sample's interior using optical techniques. The method generates an additional radiation field containing a component that reduces the excited state population of the sample at the intersection point of several standing waves. This creates a very small luminescence region within the sample, allowing high-resolution examination. The size of the luminescence region is determined by the wavelength of additional radiation and probabilities of spontaneous and forced state transitions. The method can be used to generate 3D maps of molecule densities within transparent samples like crystals, glasses, and organic dyes.
The document describes an SMS on FiRe system created by Pierre Masure. It includes modules for sensors that can detect temperature, light, and Bluetooth signals. The system is capable of sending SMS alerts if a fire is detected by measuring temperature above 60 degrees Celsius. It also includes additional modules for weather monitoring, statistics collection, and sending real-time sensor readings via Bluetooth.
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1. REPORT OF THE MULTIMEDIA PROJECT 2009, UMONS MA2, DECEMBER 2009 1
Vibration sensor based on optical fibre
Conception and simulation
Pierre Masure, Laurent-Yves Kalambayi
Abstract—This project concerns the development of a vibration the fiber at a given frequency. The purpose of our proposed
sensor based on the use of optical fibres, which will compensate solution will be to recover the excitation spectrum in the
for the limitations of sensors based on classical technologies. optical domain. In order to do this, we should try to have the
The approach considered concerns the realisation of a vibration
sensor based on the polarisation properties of optical fibres. The best similarity between the excitation and the optical domain
polarisation state of the observed light at the output of a fibre in an spectrum point of view: the recovery of the excitation
varies with the vibrations. In this context, it is proposed to design spectrum in frequency and in amplitude at the optical output
a simple sensor using out of the shelf equipment. The model has of the sytem should be obtained. The model of the Fiber
been implemented on Matlab. The practical testing of the model Stretcher used is the PZ2-PM-1.5-FC/APC-E operating at a
has also been included to this project. We can conclude that
the vibration sensor created provides the results we expected wavelength of 1550 nm with a fiber stretch of 3.8µm/V, the
theorically. We obtain similar results for the model implemented fiber length is 40 meters and the fiber wind is a 2-Layer wind.
on Matlab compared to the real device. These results prove that The fiber used in the stretcher is a polarisation maintaining
the sensor is operational. fiber which inhibits the polarisation mode coupling present in
Index Terms—optical, fibre, sensor, vibration. normal optical fibers.
I. I NTRODUCTION III. T HE SENSOR MODEL
T HIS project concerns the development of a vibration
sensor based on the use of optical fibres, which will
compensate for the limitations of sensors based on classical
To recover the excitation spectrum, we must create a system
which can provide us a way to recover this spectrum in the
optical domain.
technologies. Sensors based on optical fibres are insensitive
to electromagnetic perturbations, usable in harsh environ-
ment (flammable environment, high temperatures, corrosion
risks,...) and are appropriate for distributed measurements. The
approach considered concerns the realisation of a vibration
sensor based on the polarisation properties of optical fibres.
The polarisation state of the observed light at the output of a
fibre varies with the vibrations. In this context, it is proposed to
design a simple sensor using out of the shelf equipment. After
designing the system, the project will consist in simulating
his efficiency on Matlab. Beforehand, it will be necessary to
implement a fibre model taking into account the vibration
effects on the polarisation properties. An additionnal part,
which is the practical testing of the model, is included to this
project. Fig. 1. Sensor model
II. T HE FIBER STRECTHER On Fig.1 we show the measurement tool we created to
The OPTIPHASE PZ2 High-efficiency Fiber Stretcher is a perform the given task, the vibration measurement. To perform
fiber wound piezo-electric element for use in a wide range the task, we need:
of optical interferometric measurement and sensing system • a laser
applications. Typical uses include open loop demodulation, • a polarizer
sensor simulation, white-light scanning interferometers and • the piezo-electric fiber stretcher
large angle modulation of interferometric phase. PZ2 Fiber • an analyzer
stretcher are available with SMF-28e+ or PM [PANDA] fiber • an oscilloscope+FFT
types. We will use the fiber stretcher as a device to simulate We suppose that a laser launches any polarisation state at
the vibration: the piezo-electric element which will stretch the input of the fiber. Therefore, we use a linear polarizer
in order to have a defined state of polarisation at the input of
M. Masure and Kalambayi are with the Department of Electrical Engineer-
ing, UMons, Belgium the piezo-electric fiber stretcher. The light travels through the
Manuscript received December 14, 2009; revised December 19, 2009. fiber winded up the piezo-electric element which stretches the
2. REPORT OF THE MULTIMEDIA PROJECT 2009, UMONS MA2, DECEMBER 2009 2
fiber with an elongation driven by the signal provided by the of the stretcher and q is the azimuth of the fastest linear
generator. The elongation has for effect to modifies the light polarization.
polarisation state. After the piezo-electric fiber stretcher, we z = zi + kxexc (5)
put a polariser which is used to analyze the light coming from
where z is the full length of the fiber in the fiber stretcher, zi
the stretcher. This particular polariser is denoted by the term
the initial length of the fiber (40m), kxexc the elongation of
’analyzer’.
the fiber due to the mechanical excitation, k the coefficient
The physical idea behind this construction is that the power
describing the linear stretch of the fiber with the voltage
of the light will have an initial value if there is no stretch.
(3.8µm/V), xexc the excitation signal of the piezo-electric
When we induce a stretch to the fiber, the light polarisation
element in Volt.
state of the light will be modifiedin time. As a consequence,
We make a simplification and suppose that q = 0 (x and y
the power transmitted by the analyzer will vary in time.
axes aligned with the eigenmodes of the PMF-fiber):
Physically, we feel that we could recover some spectrum
information in the optical domain. Let us put some math-
1 0 0 0
ematics behind this to prove that our system works. The 0 1 0 0
formalism used to analyze this system is the Stokes formalism. Ms = 0 0 cos(δ) cos(δ)
(6)
The Stokes formalism describes the polarisation state of the 0 0 −sin(δ) cos(δ)
light through a 4-dimensional real vector. Let us analyze our
vibration tool mathematically: sint = Ms s (7)
The polarisation state launched by the laser is random.
At the output of the fiber stretcher, we obtain:
We use a polariser to modify that random polarisation state
to obtain a well-defined polarisation state: T
sint = 1 0 cos(δ) −sin(δ) (8)
T
sin = 1 cos(2φ) sin(2φ) 0 (1) The analyzer can be described by an 4x4 Mueler matrix:
with φ corresponding to the polarisation angle with respect
to the x-Axis. Let us assume that φ=45 ˚ : 1 cos(2θ) sin(2θ) 0
1 cos(2θ) cos(2θ)2 sin(2θ)cos(2θ) 0
T Ma =
sin = 1 0 1 0 (2) 2 sin(2θ) sin(2θ)cos(2θ) sin(2θ)2 0
0 0 0 0
We describe the piezo-electric fiber stretcher with the fol- (9)
lowing 4x4 Mueller matrix: If we consider that θ=45 ˚ :
m11 m12 m13 m14 1 0 1 0
m21 m22 m23 m24 1 0 0 0 0
Ms = (3) Ma = (10)
m31 m32 m33 m34 2 1 0 1 0
m41 m42 m43 m44 0 0 0 0
sout = Ma sint (11)
m11 = 1, m12 = 0, m13 = 0
m14 = 0, m21 = 0, m31 = 0, m41 = 0 1 T
sout = 1 + cos(δ) 0 1 + cos(δ) 0 (12)
δ δ 2
m22 = cos2 + sin2 cos4q
2 2
δ 1 T
m23 = sin2 sin4q sout = 1 + cos(∆βz) 0 1 + cos(∆βz) 0 (13)
2 2
m24 = −sinδsin2q The global power at the output is given by the first element
δ of sout :
m32 = sin2 sin4q 1
2 sout0 = (1 + cos(∆βz)) (14)
δ δ 2
m33 = cos2 − sin2 cos4q
2 2 ∆β is constant with the stretch because we are working with
m34 = sinδcos2q a PMF-fiber. This has been proven in the reference [1][2].
m42 = sinδsin2q 1
sout0 = (1 + cos(∆β(zi + kxexc )) (15)
m43 = −sinδcos2q 2
m44 = cosδ Let us suppose that the excitation is sinusoidal:
xexc = Asin(2πfexc t) (16)
δ = ∆βz (4)
where ∆β is the fiber birefringence and δ is the phase 1
retardance between the two eigenmodes of the PMF-fiber sout0 = (1 + cos (∆β (zi + kAsin(2πfexc t)))) (17)
2
3. REPORT OF THE MULTIMEDIA PROJECT 2009, UMONS MA2, DECEMBER 2009 3
We see in this equation that the temporal evolution of the Finally, for the equation (with x cosinusoidal) cos(p1 + x),
output power depends on fexc . The information related to the we have the following spectral components (frequency:
mechanical excitation is somehow comprised in equation (18). amplitude)
Let us analyze equation (19) in detail to see if the optical 1 1
DC : cos(p1 ) − p2 cos(p1 ) (26)
spectrum is a good image of the excitation spectrum. 2 22
To perform this, we will use the Taylor expansion in the
1 p3 1
next section. fexc : −sin(p1 )p2 + sin(p1 ) 2 (1 + ) (27)
6 2 2
IV. N ON - LINEARITIES IN THE SENSOR 1 p2
2fexc : − cos(p1 ) 2 (28)
Let us develop equation (18): 2 2
1 p3
sout0
1
= 1 + cos ∆βzi + ∆βkA sin2πfexc t (18)
sin(p1 ) 2
3fexc : (29)
2 6 4
p1 p2 When performing simplifications, you have:
Let us consider the Taylor expansion of this function: p2
2
DC : cos(p1 )(1 − ) (30)
cos(p1 + x) = cos(p1 ) − sin(p1 )x 4
1 1 p2
− cos(p1 )x2 + sin(p1 )x3 fexc : −sin(p1 )p2 (−1 + 2
) (31)
2 6 8
1
+ cos(p1 )x4 + . . . (19)
24 p2
2
2fexc : − cos(p1 ) (32)
when considering that 4
x = p2 cos(2πfexc t) (20) p3
2
3fexc : sin(p1 ) (33)
p1 = ∆βzi (21) 8
Let us analyze these results for a sinusoidal excitation at a
p2 = ∆βkA (22) frequency fexc :
p2 contains the information about the amplitude of the • The system is non-linear: the optical spectrum is not the
mechanical excitation. We will assume that non-linearities are same as the excitation spectrum.
non-negligble for the first three orders of the Taylor expansion. – fexc at the excitation creates fexc , 2fexc , 3fexc ,... in
Let us modify this equation to analyze the contribution of the optical domain.
the higher orders on the lower orders. – The amplitudes aren’t directly recoverable because
The second order term gives: we want to have access to p2 which has the infor-
mation about the amplitude of the mechanical exci-
1
x2 = p2 cos2 (2πfexc t) = p2 (1 + cos(2π(2fexc )t)) (23)
2 2
tation. There is no term directly proportional to p2 .
2 We need to perform some mathematical operations
The third order term gives: to recover the good amplitudes.
• The linear term provides us fexc .
x3 = p3 cos3 (2πfexc t) =
2 • The linear term doesn’t provides us directly the good
1
p3 (1 + cos(2π(2fexc )t))cos(2πfexc t) (24)
2
amplitude.
2 • All the coefficients depends on p1 .
The Simpson product gives: • By playing on the p1 parameter, we can suppress or
maximize the amplitude of the fundamental and the
cos(2π(2fexc )t)cos(2πfexc t) = higher orders.
1 • To recover the p2 amplitude at the first order, we need
(cos(2π(3fexc )t) + cos(2πfexc t)) (25)
2 to solve the equation with provides us more than one
solution.
– The p2 amplitude isn’t easily recoverable at fexc .
• If we consider the second order, we only have one
physical solution to the equation to find the p2 amplitude.
– Why? A negative amplitude isn’t physical.
• To conclude: we should consider the measurement of
the amplitude at 2fexc to obtain an equation which can
provide us p2 .
• To perform this, we should maximize cos(p1 ): the mea-
p2
sure at 2fexc gives us − 42
4. REPORT OF THE MULTIMEDIA PROJECT 2009, UMONS MA2, DECEMBER 2009 4
• The maximization/minimization of cos(p1 ) is the same
as maximizing/minimizing the DC power.
– This can be pratical for an experimental use.
• p1 is linked to the the wavelength of the source.
– We can tune p1 (and the amplitude of the harmonics)
by changing the wavelength of the source.
2π 2πfopt
p1 = ∆βzi = ∆nzi = ∆nzi (34)
λopt c
where fopt is the frequency of the laser,λopt the wavelength
of the laser,∆n is the difference in refractive indexes between
the x and y axes of the PMF fiber.
Now, we know that the coefficients varies with cos(p1 ) or
sin(p1 ). Changing fopt linearly will modify the coefficients
periodically. This result is very important if we want to
influence the performance of the vibration sensor: we can act
on the linearity of the system by modifying the wavelength of
the source.
V. M ATLAB RESULTS
We implemented the vibration sensor model on Matlab Fig. 3. y(f)(m): excitation elongation, sout(f)(dB): power in the optical
to simulate its working in order to validate the theory we domain; suppression of H2
developped during this project. We launched a sinusoidal
excitation into the system at 120Hz. We validated the theory
first for a random frequency of the laser in order to see VI. E XPERIMENTAL RESULTS
the generation of harmonics until the third order (the other
We experimentally implemented the vibration sensor to test
are neglegible). We see that there is a generation of these
the model in order to validate the theory we developped during
frequencies fexc , 2fexc , 3fexc ,... This result is provided in
this project. We launched a sinusoidal excitation thanks to the
Fig. 2. On the other hand, we tuned the frequency (fopt ) of the
generator into the system at 100Hz. We valitade the theory
first for a random frequency of the laser in order to see
the generation of harmonics until the third order (the other
are neglegible). We see that there is a generation of these
frequencies fexc , 2fexc , 3fexc ,... This result is provided in
Fig. 4. On the other hand, we tuned the frequency (fopt ) of the
Fig. 4. Power in the optical domain; generation of H1 H2 H3
laser in order to increase the amplitude of the DC component.
The amplitude of fundamental decreases. The first harmonic
at 2fexc increases. This result is provided in Fig. 5. However,
the system we experimentally implemented isn’t completely
Fig. 2. y(f) (m): excitation elongation, sout(f)(dB): power in the optical the same as the model tested on Matlab because the parameter
domain; generation of H1 H2 H3 θ isn’t equal to 45 ˚ for the analyzer. Therefore, we couldn’t
have an exact replica of the amplitudes we simulated with
laser in order to maximize the amplitude of the fundamental Matlab. These results prove that the spectrum depends on the
frequency fexc . The first harmonic at 2fexc is then suppressed. wavelength of the source and that by modifying its wavelength
This result is provided in Fig. 3. we can suppress or maximize the fundamental and the higher
5. REPORT OF THE MULTIMEDIA PROJECT 2009, UMONS MA2, DECEMBER 2009 5
orders.
Fig. 5. Power in the optical domain; maximization of H2
VII. P ERSPECTIVES
We don’t have the exact experimental replica of the model
implemented on Matlab. Therefore, we could modify our
model implemented on Matlab and generalize it with a variable
θ angle. When we will be able to have the exact replica of the
model implemented on Matlab on the experimental way, we
will have the possibility to compare the amplitudes obtained
experimentally with the simulated results.
VIII. C ONCLUSION
This project concerned the development of a vibration sen-
sor based on the use of optical fibres. The approach considered
concerned the realisation of a vibration sensor based on the
polarisation properties of optical fibres. The polarisation state
of the observed light at the output of a fibre varies with the
vibrations. After designing the system, the project consisted
in simulating his efficiency on Matlab. The practical testing
of the model has also been included to this project.
We can conclude that the vibration sensor created provides
the results we expected theorically. We obtain coherent results
between the model implemented and the real device. These
results prove that the sensor is operational.
ACKNOWLEDGMENT
The authors would like to thank the professor Marc Wuilpart
for his teaching method.
R EFERENCES
[1] C. Crunelle, M. wuilpart, P. Mgret,Sensitivity of Polarization Main-
taining Fibres to Temperature and Strain for Sensing Applications, pp.
205 to 208, in Proc. IEEE/LEOS Benelux Chapter 2006, Eindhoven, The
Netherlands,
[2] N. Ashby, D. A. Howe, J. Taylor, A. Hati, C. Nelson [National Institute
of Standards and Technology],Optical Fiber Vibration and Acceleration
Model, pp. 1 to 5.