The star camera baffles for the BLAST-TNG experiment were designed to block sunlight from blinding the star cameras while allowing light from stars to pass through. The baffles were 72 inches long and 5.5 pounds, exceeding the length of the sunshields. Carbon fiber tubes and aluminum rings were used to construct two cylindrical trusses. Carbon fiber disks and black aluminum wrap were added inside to absorb unwanted light bouncing up to three times within. Python code determined optimal positions for the disks to block 100% of undesirable light from reaching the lens. Plots validated the baffles' effectiveness.
The document discusses the development of a Littrow spectrograph and its advantages over a classical spectrograph. It describes using the Littrow configuration to enable amateur astronomers to conduct research through spectroscopy. Details are provided on constructing the spectrograph, aligning it, and obtaining spectra of various astronomical objects using a DSLR camera mounted to a telescope.
Technical lighting is important for film shots in the woods where there is no power source. High lighting positions above subjects can provide the best source of light, allowing clear facial expressions to be filmed while also casting eerie shadows. The document discusses taking test shots and editing at McIlroy Park for a media film or movie, with examples of different shot types categorized by lighting and camera angle, including high shots, close ups, long distance shots, low angle shots, inline angle shots and high angle shots.
Mike is a Space Studies major who has recently gotten into amateur astronomy. He documents his experiences capturing images of various solar system objects like the Moon and planets using a Celestron Nexstar 5SE telescope and NexImage 5 imager. He shows his first attempts at imaging Saturn, as well as images of the Lagoon Nebula (M8) captured from the online Micro Observatory telescope. Mike concludes by showcasing a stunning image of the Lagoon Nebula taken by another amateur astronomer using longer exposures.
Technical lighting is important for film shots in wooded areas without power sources, as camera lighting alone may not be sufficient. Positioning high lighting above subjects, such as a torch above a character's head, can cast eerie shadows while also allowing facial expressions to be captured more clearly. The document discusses taking test shots and videos of McIlroy Park for a media film or movie, including location test shots, editing, and different shot types from various angles and distances with varying light levels.
This document provides information on Tasco brand binoculars, spotting scopes, telescopes, and riflescopes. It includes specifications for various models of binoculars, such as magnification, objective lens size, lens coating, waterproofing, and whether they can adapt to a tripod. The document promotes Tasco's products as providing bright, sharp images through precision engineering and coating of lenses. It emphasizes features for outdoor and wildlife viewing applications.
Photography as foundation of cinematographyIvy Autor
Photography is the art and practice of creating images by recording light or electromagnetic radiation, either chemically on film or electronically with an image sensor. Cinematography is the technique of motion picture photography, including both shooting and developing film. Key lighting, fill lighting, and back lighting are used to illuminate subjects, with different colored lights and lamp types like tungsten and HMI used to achieve desired moods and effects. Camera settings and lens focal lengths and apertures can influence depth of field and bokeh. Popular cameras for cinematography include the Arriflex and the Aaton, while digital options continue to emerge alongside film.
This document discusses different types of camera shots and angles that can be used in filmmaking. It begins by explaining the rule of thirds for framing subjects and positioning elements in a shot. Common basic shots are then outlined, including extreme wide shots, wide shots, medium shots, medium close ups, and close ups. More advanced shot types such as two shots, cutaways, over the shoulder shots, and point of view shots are also described. The document concludes by discussing using a large aperture to create selective focus and rack focus by changing the point of focus within a shot.
The document discusses the development of a Littrow spectrograph and its advantages over a classical spectrograph. It describes using the Littrow configuration to enable amateur astronomers to conduct research through spectroscopy. Details are provided on constructing the spectrograph, aligning it, and obtaining spectra of various astronomical objects using a DSLR camera mounted to a telescope.
Technical lighting is important for film shots in the woods where there is no power source. High lighting positions above subjects can provide the best source of light, allowing clear facial expressions to be filmed while also casting eerie shadows. The document discusses taking test shots and editing at McIlroy Park for a media film or movie, with examples of different shot types categorized by lighting and camera angle, including high shots, close ups, long distance shots, low angle shots, inline angle shots and high angle shots.
Mike is a Space Studies major who has recently gotten into amateur astronomy. He documents his experiences capturing images of various solar system objects like the Moon and planets using a Celestron Nexstar 5SE telescope and NexImage 5 imager. He shows his first attempts at imaging Saturn, as well as images of the Lagoon Nebula (M8) captured from the online Micro Observatory telescope. Mike concludes by showcasing a stunning image of the Lagoon Nebula taken by another amateur astronomer using longer exposures.
Technical lighting is important for film shots in wooded areas without power sources, as camera lighting alone may not be sufficient. Positioning high lighting above subjects, such as a torch above a character's head, can cast eerie shadows while also allowing facial expressions to be captured more clearly. The document discusses taking test shots and videos of McIlroy Park for a media film or movie, including location test shots, editing, and different shot types from various angles and distances with varying light levels.
This document provides information on Tasco brand binoculars, spotting scopes, telescopes, and riflescopes. It includes specifications for various models of binoculars, such as magnification, objective lens size, lens coating, waterproofing, and whether they can adapt to a tripod. The document promotes Tasco's products as providing bright, sharp images through precision engineering and coating of lenses. It emphasizes features for outdoor and wildlife viewing applications.
Photography as foundation of cinematographyIvy Autor
Photography is the art and practice of creating images by recording light or electromagnetic radiation, either chemically on film or electronically with an image sensor. Cinematography is the technique of motion picture photography, including both shooting and developing film. Key lighting, fill lighting, and back lighting are used to illuminate subjects, with different colored lights and lamp types like tungsten and HMI used to achieve desired moods and effects. Camera settings and lens focal lengths and apertures can influence depth of field and bokeh. Popular cameras for cinematography include the Arriflex and the Aaton, while digital options continue to emerge alongside film.
This document discusses different types of camera shots and angles that can be used in filmmaking. It begins by explaining the rule of thirds for framing subjects and positioning elements in a shot. Common basic shots are then outlined, including extreme wide shots, wide shots, medium shots, medium close ups, and close ups. More advanced shot types such as two shots, cutaways, over the shoulder shots, and point of view shots are also described. The document concludes by discussing using a large aperture to create selective focus and rack focus by changing the point of focus within a shot.
This document summarizes recent advances in a space photovoltaic concentrator technology being developed by a team under a NASA Phase II SBIR program. Key advances include a flat Fresnel lens made of silicone prisms on glass, use of more efficient 4-junction solar cells, and an articulating receiver that enables single-axis sun tracking while maintaining focus over a wide range of incidence angles. Outdoor tests show the lens maintains high optical efficiency from 0-50 degree angles as the receiver articulates. The concentrator achieves a high power-to-weight ratio of around 900W/kg based on initial performance metrics of the key components.
PAggieSpec is a low-cost, low-resolution optical spectrograph designed and built by students. It uses commercial lenses and CCD cameras to perform spectroscopy at a fraction of the cost of custom components. Testing showed PAggieSpec can reliably obtain spectra in the 4000-6000 angstrom range, but further investigation is needed to extend the coverage to the full visible range. While low-cost, PAggieSpec experiences light loss in the red wavelengths that requires more study to understand and address. The system demonstrates the potential of using commercial lenses for astronomy instrumentation at reduced cost.
PAggieSpec is a low-cost, low-resolution optical spectrograph designed and built by students. It uses commercial lenses and CCD cameras to perform spectroscopy at a fraction of the cost of custom components. Testing showed PAggieSpec can reliably obtain spectra in the 4000-6000 angstrom range, but further investigation is needed to understand light loss in the red wavelengths and improve coverage over the full visible range. The system provides a low-cost option for institutions to perform optical spectroscopy.
The James Webb Space Telescope (JWST) will replace the Hubble Telescope and observe stars and galaxies as they formed after the Dark Ages. It uses lightweight cryogenic mirrors made of beryllium and coated with gold to capture infrared light from up to 13.4 billion years ago. The JWST's mirrors are segmented and foldable to fit inside the launch vehicle. It also uses a microshutter analysis system to selectively allow photons to enter and be analyzed by a spectrograph to study the origins of the universe.
1) The document discusses the author's work over the summer using a UV laser cutter to develop various applications including electrostatic adhesion, capacitive sensing, quadcopter perching, and experimental spring designs.
2) For electrostatic adhesion, the author was able to achieve adhesion using two composite materials with custom designed and manufactured electrodes patterned using the laser cutter.
3) For capacitive sensing, the author recreated capacitive changes by etching a fine electrode pattern on metallized film, though further analysis is still needed.
4) For quadcopter perching, the author used the laser cutter to make lightweight grippers for a small quadcopter to attempt perching on rough
Hahnenberg Observatory in Michigan presents information for those interested in building a domed observatory, learning about the different kinds of telescopes and CCD cameras available. Sample astrophotographs, and types of CCD software, are also included in the presentation.
Design and Analysis of Thin Film Silicon Solar cells Using FDTD MethodDr. S. Saravanan
This document summarizes the design and analysis of thin film silicon solar cells using the finite-difference time-domain (FDTD) method. It discusses how thin film technology can lower the cost of silicon solar cells while light trapping techniques like photonic crystals and diffraction gratings can enhance light absorption. The author simulates various thin film solar cell designs in FDTD and finds that a design with distributed Bragg reflector pairs and a binary diffraction grating achieves the highest efficiency. Relative enhancements in short circuit current and solar cell efficiency of up to 64.2% are observed for thicker cell designs with these light trapping structures.
The document summarizes a presentation given at the IVth International Conference on Advances in Energy Research held from 10-12 December 2013 at IIT Bombay in Mumbai. The presentation was given by Sonali Das from the DST SOLAR HUB Centre of Excellence for Green Energy and Sensor Systems at Bengal Engineering and Science University. The presentation discussed using a mixture of metal and dielectric nanoparticles to improve the performance of silicon solar cells. It described how nanoparticles can be used to increase photon injection into the cell and light absorption within it. Through simulations and experiments, an optimized mixture of silver and silica nanoparticles was found to increase the number of electron-hole pairs collected compared to using just one type of nanoparticle.
This project aimed to develop neutron radiography capabilities using a radioisotope neutron source. Design and modeling was conducted at Colorado School of Mines, while experiments were performed at a research reactor. Shielding was added using borated polyethylene and paraffin mixtures to reduce neutron dose. Foil activation experiments tested gold, indium, dysprosium and cadmium foils, with gold and indium chosen for capturing images on film due to their dark exposures. A pinhole collimator design was 3D printed and used to capture low detail images, though a Soller collimator could improve flux and image quality. The project outlined methods for shielding, foil selection, equipment design and film development to perform neutron
This document discusses a proposed large telescope that uses a holographically-corrected membrane mirror. It aims to demonstrate the feasibility of such a telescope in the optical wavelengths. It describes how holographic correction can improve the image quality from an aberrated membrane mirror. The document also outlines plans to build a 1-meter prototype and conduct further analysis and testing to develop a 10-meter telescope using this technology.
Students aged 12 to 18 observed the Big Bang using an 11-inch telescope. They measured redshifts of galaxies and deduced quantitative conclusions about the age of the universe and density of dark matter. Key findings included:
- Measuring significant redshifts of 0.0077 and 0.003 for galaxies NGC 3516 and M66, matching literature values.
- Interpreting the main emission line at 6590 Angstroms as hydrogen-alpha, indicating a redshift of 0.0077 for NGC 3516.
- Concluding the Big Bang observations were highly significant based on statistical analysis, despite limitations of the small telescope.
This document describes a new space photovoltaic concentrator system using flat glass/silicone Fresnel lenses, 4-junction IMM solar cells, graphene-based radiators, and articulating photovoltaic receivers. A new flat lens design was developed using glass or embedded metal mesh to support silicone prisms. Testing showed the lenses maintained high transmittance after proton irradiation. A 4-junction IMM cell achieved 31% efficiency. A graphene radiator offered unprecedented thermal and strength properties. The new concentrator components were integrated into a test module and could achieve 900 W/kg for future space missions.
1) The document describes a proposed design for an unobscured astronomical camera with a 22 degree field of view and f/2 speed, to be used for a new large telescope in Hawaii.
2) It explores starting with an existing 5-mirror spherical design that was used on space missions, but determines a 3-mirror freeform aspheric design may be better.
3) The document presents an example 3-mirror freeform aspheric design that meets the requirements, with all mirrors tilted and shaped as aspheres to produce an unobscured 22 degree field of view at f/2.
The document discusses the design of resonant cavities for testing the EM Drive phenomenon. Early designs using thin copper sheet metal were found to thermally warp over time, degrading resonance. A new design was proposed using a solid aluminum slug turned on a lathe, allowing for greater thickness, precision and resistance to warping. Simulations were performed to refine the dimensions and spherical end caps were proposed to improve resonance quality. The final planned design was to recreate the dimensions used successfully by Iulian Berca using the copper plate, in order to validate his claimed results.
(1) The document describes an infrared plastic solar cell that uses nanotechnology to absorb invisible infrared rays from sunlight for power generation. (2) It consists of cadmium selenide nano rods bound with a polymer that allow it to detect infrared light and generate electrons and electron holes to produce a current. (3) The plastic solar cell is more efficient than traditional silicon solar cells, flexible, lightweight, and can generate power even on cloudy days by absorbing infrared rays.
The Effects on Rapid Laser Heating on a Au (111) SampleSean Nees
The document discusses an experiment measuring the thermal expansion of a gold sample using a scanning tunneling microscope when heated with a laser. When shot with a <80mW laser, the gold sample expands over 6000 angstroms. Before and after images show no change in the gold surface, but some scans show changes in thiol molecules on the gold surface. Additional experiments are needed to better understand the time-dependent effects and impact on the scanning tip.
This document discusses various devices used to reduce scattered radiation in diagnostic radiology, including filters, beam limiting devices, beam centering devices, and radiographic grids. It provides details on how each device works to absorb low-energy photons and restrict the x-ray beam, thereby improving image quality by reducing noise from scattered radiation. Key aspects covered include the principles of filtration, types of beam collimators, performance testing of grids using factors like contrast improvement and primary transmission, and the benefits of using these devices to decrease patient dose and increase diagnostic value.
Optimization of multijunction solar cell by wafer ray tracer for development ...eSAT Journals
Abstract Optical losses limit the excess carriers generation in absorber part of multijuction (MJ) solar cell. The generation of excess carriers is directly proportional to photogenerated current solar cell. Therefore, reduction of optical losses is fundamentally important for improving the power conversion efficiency. Thickness of layers strongly influences the performance of MJ solar cell. In this study we simulated a MJ solar cell of Air/ZnO/SiC/c-Si/a-Si(n)/Al structure using Wafer Ray Tracer (WRT) simulation software and optimized the thicknesses of the layers for photogenerated current. The simulation result shows that without SiC layer, only 57.48% of incident light is absorbed and generates 26.85 mA/cm2 photogenerated current in solar cell. A 70 nm thickness of optimized SiC layer is increasing the light absorption 22.16% and photogenerated current 38.54%. Result shows that there is no transmission of light through the absorber layer. The MJ solar cell without Back Surface Field (BSF) layer of a-Si(n) shows photogenerated current of 37.05 mA/cm2 which can be improved to 37.24 mA/cm2 with a 100 nm thickness of a-Si(n). The c-Si absorber layer shows highest absorptance within 500 nm-1000 nm wavelength of light spectrum with 100 nm thickness of a-Si(n). An a-Si(n) BSF layer at the back surface minimizes the effective back-surface recombination velocity and improves the collection probability of minority carriers of solar cell. Furthermore a 100 nm Al rear contact improves the photogenerated current of MJ solar cell to 37.25 mA/cm2. An Al rear contact layer improves the mechanical strength of c-Si absorber layer. The electrical property of Al improves the excess carriers’ collection probability of MJ solar cell. Keywords: Wafer Ray Tracer, Simulation, Multijunction Solar Cell, Photogeneration, Back Surface Field.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
This document summarizes recent advances in a space photovoltaic concentrator technology being developed by a team under a NASA Phase II SBIR program. Key advances include a flat Fresnel lens made of silicone prisms on glass, use of more efficient 4-junction solar cells, and an articulating receiver that enables single-axis sun tracking while maintaining focus over a wide range of incidence angles. Outdoor tests show the lens maintains high optical efficiency from 0-50 degree angles as the receiver articulates. The concentrator achieves a high power-to-weight ratio of around 900W/kg based on initial performance metrics of the key components.
PAggieSpec is a low-cost, low-resolution optical spectrograph designed and built by students. It uses commercial lenses and CCD cameras to perform spectroscopy at a fraction of the cost of custom components. Testing showed PAggieSpec can reliably obtain spectra in the 4000-6000 angstrom range, but further investigation is needed to extend the coverage to the full visible range. While low-cost, PAggieSpec experiences light loss in the red wavelengths that requires more study to understand and address. The system demonstrates the potential of using commercial lenses for astronomy instrumentation at reduced cost.
PAggieSpec is a low-cost, low-resolution optical spectrograph designed and built by students. It uses commercial lenses and CCD cameras to perform spectroscopy at a fraction of the cost of custom components. Testing showed PAggieSpec can reliably obtain spectra in the 4000-6000 angstrom range, but further investigation is needed to understand light loss in the red wavelengths and improve coverage over the full visible range. The system provides a low-cost option for institutions to perform optical spectroscopy.
The James Webb Space Telescope (JWST) will replace the Hubble Telescope and observe stars and galaxies as they formed after the Dark Ages. It uses lightweight cryogenic mirrors made of beryllium and coated with gold to capture infrared light from up to 13.4 billion years ago. The JWST's mirrors are segmented and foldable to fit inside the launch vehicle. It also uses a microshutter analysis system to selectively allow photons to enter and be analyzed by a spectrograph to study the origins of the universe.
1) The document discusses the author's work over the summer using a UV laser cutter to develop various applications including electrostatic adhesion, capacitive sensing, quadcopter perching, and experimental spring designs.
2) For electrostatic adhesion, the author was able to achieve adhesion using two composite materials with custom designed and manufactured electrodes patterned using the laser cutter.
3) For capacitive sensing, the author recreated capacitive changes by etching a fine electrode pattern on metallized film, though further analysis is still needed.
4) For quadcopter perching, the author used the laser cutter to make lightweight grippers for a small quadcopter to attempt perching on rough
Hahnenberg Observatory in Michigan presents information for those interested in building a domed observatory, learning about the different kinds of telescopes and CCD cameras available. Sample astrophotographs, and types of CCD software, are also included in the presentation.
Design and Analysis of Thin Film Silicon Solar cells Using FDTD MethodDr. S. Saravanan
This document summarizes the design and analysis of thin film silicon solar cells using the finite-difference time-domain (FDTD) method. It discusses how thin film technology can lower the cost of silicon solar cells while light trapping techniques like photonic crystals and diffraction gratings can enhance light absorption. The author simulates various thin film solar cell designs in FDTD and finds that a design with distributed Bragg reflector pairs and a binary diffraction grating achieves the highest efficiency. Relative enhancements in short circuit current and solar cell efficiency of up to 64.2% are observed for thicker cell designs with these light trapping structures.
The document summarizes a presentation given at the IVth International Conference on Advances in Energy Research held from 10-12 December 2013 at IIT Bombay in Mumbai. The presentation was given by Sonali Das from the DST SOLAR HUB Centre of Excellence for Green Energy and Sensor Systems at Bengal Engineering and Science University. The presentation discussed using a mixture of metal and dielectric nanoparticles to improve the performance of silicon solar cells. It described how nanoparticles can be used to increase photon injection into the cell and light absorption within it. Through simulations and experiments, an optimized mixture of silver and silica nanoparticles was found to increase the number of electron-hole pairs collected compared to using just one type of nanoparticle.
This project aimed to develop neutron radiography capabilities using a radioisotope neutron source. Design and modeling was conducted at Colorado School of Mines, while experiments were performed at a research reactor. Shielding was added using borated polyethylene and paraffin mixtures to reduce neutron dose. Foil activation experiments tested gold, indium, dysprosium and cadmium foils, with gold and indium chosen for capturing images on film due to their dark exposures. A pinhole collimator design was 3D printed and used to capture low detail images, though a Soller collimator could improve flux and image quality. The project outlined methods for shielding, foil selection, equipment design and film development to perform neutron
This document discusses a proposed large telescope that uses a holographically-corrected membrane mirror. It aims to demonstrate the feasibility of such a telescope in the optical wavelengths. It describes how holographic correction can improve the image quality from an aberrated membrane mirror. The document also outlines plans to build a 1-meter prototype and conduct further analysis and testing to develop a 10-meter telescope using this technology.
Students aged 12 to 18 observed the Big Bang using an 11-inch telescope. They measured redshifts of galaxies and deduced quantitative conclusions about the age of the universe and density of dark matter. Key findings included:
- Measuring significant redshifts of 0.0077 and 0.003 for galaxies NGC 3516 and M66, matching literature values.
- Interpreting the main emission line at 6590 Angstroms as hydrogen-alpha, indicating a redshift of 0.0077 for NGC 3516.
- Concluding the Big Bang observations were highly significant based on statistical analysis, despite limitations of the small telescope.
This document describes a new space photovoltaic concentrator system using flat glass/silicone Fresnel lenses, 4-junction IMM solar cells, graphene-based radiators, and articulating photovoltaic receivers. A new flat lens design was developed using glass or embedded metal mesh to support silicone prisms. Testing showed the lenses maintained high transmittance after proton irradiation. A 4-junction IMM cell achieved 31% efficiency. A graphene radiator offered unprecedented thermal and strength properties. The new concentrator components were integrated into a test module and could achieve 900 W/kg for future space missions.
1) The document describes a proposed design for an unobscured astronomical camera with a 22 degree field of view and f/2 speed, to be used for a new large telescope in Hawaii.
2) It explores starting with an existing 5-mirror spherical design that was used on space missions, but determines a 3-mirror freeform aspheric design may be better.
3) The document presents an example 3-mirror freeform aspheric design that meets the requirements, with all mirrors tilted and shaped as aspheres to produce an unobscured 22 degree field of view at f/2.
The document discusses the design of resonant cavities for testing the EM Drive phenomenon. Early designs using thin copper sheet metal were found to thermally warp over time, degrading resonance. A new design was proposed using a solid aluminum slug turned on a lathe, allowing for greater thickness, precision and resistance to warping. Simulations were performed to refine the dimensions and spherical end caps were proposed to improve resonance quality. The final planned design was to recreate the dimensions used successfully by Iulian Berca using the copper plate, in order to validate his claimed results.
(1) The document describes an infrared plastic solar cell that uses nanotechnology to absorb invisible infrared rays from sunlight for power generation. (2) It consists of cadmium selenide nano rods bound with a polymer that allow it to detect infrared light and generate electrons and electron holes to produce a current. (3) The plastic solar cell is more efficient than traditional silicon solar cells, flexible, lightweight, and can generate power even on cloudy days by absorbing infrared rays.
The Effects on Rapid Laser Heating on a Au (111) SampleSean Nees
The document discusses an experiment measuring the thermal expansion of a gold sample using a scanning tunneling microscope when heated with a laser. When shot with a <80mW laser, the gold sample expands over 6000 angstroms. Before and after images show no change in the gold surface, but some scans show changes in thiol molecules on the gold surface. Additional experiments are needed to better understand the time-dependent effects and impact on the scanning tip.
This document discusses various devices used to reduce scattered radiation in diagnostic radiology, including filters, beam limiting devices, beam centering devices, and radiographic grids. It provides details on how each device works to absorb low-energy photons and restrict the x-ray beam, thereby improving image quality by reducing noise from scattered radiation. Key aspects covered include the principles of filtration, types of beam collimators, performance testing of grids using factors like contrast improvement and primary transmission, and the benefits of using these devices to decrease patient dose and increase diagnostic value.
Optimization of multijunction solar cell by wafer ray tracer for development ...eSAT Journals
Abstract Optical losses limit the excess carriers generation in absorber part of multijuction (MJ) solar cell. The generation of excess carriers is directly proportional to photogenerated current solar cell. Therefore, reduction of optical losses is fundamentally important for improving the power conversion efficiency. Thickness of layers strongly influences the performance of MJ solar cell. In this study we simulated a MJ solar cell of Air/ZnO/SiC/c-Si/a-Si(n)/Al structure using Wafer Ray Tracer (WRT) simulation software and optimized the thicknesses of the layers for photogenerated current. The simulation result shows that without SiC layer, only 57.48% of incident light is absorbed and generates 26.85 mA/cm2 photogenerated current in solar cell. A 70 nm thickness of optimized SiC layer is increasing the light absorption 22.16% and photogenerated current 38.54%. Result shows that there is no transmission of light through the absorber layer. The MJ solar cell without Back Surface Field (BSF) layer of a-Si(n) shows photogenerated current of 37.05 mA/cm2 which can be improved to 37.24 mA/cm2 with a 100 nm thickness of a-Si(n). The c-Si absorber layer shows highest absorptance within 500 nm-1000 nm wavelength of light spectrum with 100 nm thickness of a-Si(n). An a-Si(n) BSF layer at the back surface minimizes the effective back-surface recombination velocity and improves the collection probability of minority carriers of solar cell. Furthermore a 100 nm Al rear contact improves the photogenerated current of MJ solar cell to 37.25 mA/cm2. An Al rear contact layer improves the mechanical strength of c-Si absorber layer. The electrical property of Al improves the excess carriers’ collection probability of MJ solar cell. Keywords: Wafer Ray Tracer, Simulation, Multijunction Solar Cell, Photogeneration, Back Surface Field.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
1. Star Camera Baffles for BLAST-TNG
University of Pennsylvania
Mark Giovinazzi, Dr. Mark Devlin
References
Introduction
Materials and Methods
Results Conclusion
Future Work
The BLAST-TNG experiment is chosen to fly in December, the eve of the
Antarctic summer; during this time of year in the South Pole, constant
sunlight is unavoidable. While BLAST-TNG benefits from such conditions
since it is powered by solar panels, the abundance of sunlight concurrently
puts the efficiency of its star cameras at extreme risk. Although the cameras
need to absorb photons from stars in front of them, the sun's immense power
would otherwise blind the cameras with unnecessary light; the star camera
baffles were designed to block all such light.
In order to create an effective design for the star camera baffles, we had to
work under several constraints. First, we had to account for the 1.6º opening
angle of the star cameras. To supply enough room for error during assembly,
our model’s opening angle was set to be 1.8º, meaning that all incoming light
with an angle of 1.8º or less will be allowed to reach the lens. The second
constraint was that the length of the star camera baffles had to exceed that of
the sunshields, which is about 69 inches; to again provide some room for
error, the total length of our design was made to be an even 72 inches. The
final model chosen involves two cylindrical trusses attached to one each
other, the first of which bolts onto the star camera and has a radius of 8.75
inches to account for the bolt pattern of the star camera and the second of
which is larger, stepping up in diameter to 11 inches to account for the ever-
increasing inside diameter due to the opening angle of the star camera baffle.
Carbon fiber tubes were selected to build our trusses in order to provide a
good blend between lightweight and strong. To support the two cylindrical
trusses and hold the tubes in place, aluminum was chosen,considering that it
is relatively cheap, light, and strong. We used the metal to make three rings,
one of which would bolt onto the star camera, while the other connected the
two different sized trusses together, and the last constrained the carbon fiber
tubes at the top of the star camera baffle. To help block light from reaching
the lens, 1/32 inch carbon fiber disks were placed in the star camera baffle in
such ways that all unnecessary light could be blocked. We then wrapped the
sides of our star camera baffle to prevent light from entering anywhere but
the opening. For this, 0.002 inch thick matte black aluminum wrap with an
absorptive rating of 95% was picked, such that light bouncing on the inside
could be easily absorbed. We decided that if a photon were to bounce more
than three times off of this foil, we would no longer care about blocking it, as
it will have a 99.9875% chance of having been absorbed. Finally, the trusses
were spray painted a flat black to absorb, while the outside would be coated
in a glossy white to reflect, such that the star camera baffle does not overheat.
Having the general structural design in place, the only task remaining was to
determine the optimal positioning of the carbon fiber baffles such that all
unwanted light is blocked. With the three bounce limit in mind, we needed to
position a series of disks inside the star camera baffle to do the blocking of
all light that bounces between one and three times and would otherwise reach
the star camera lens. Note that if the photon bounces 0 times, it is coming
from the front and is therefore light that we care to observe. A unique code
was written using Python to determine exact locations of these carbon fiber
baffles, the result of which produced their locations in such fashion as to
absorb 100% of light our circumstances deemed undesirable.
Standing at 72 inches and weighing in at 5.5 pounds, the new star camera
baffles designed for the BLAST-TNG experiment are 40% longer and
40% lighter than those used for the previous experiment, BLAST-Pol. The
additional length was a necessary improvement because of the updated
design of the experiment, since the new sunshields will be bigger and
therefore reflect more light; they had to be long enough to exceed this.
However, the fact they they are so much lighter allows for the extra
length, and in addition induces less hull on the experiment.
Not sure if there are any general BLAST references I should include here.
The current launch date for BLAST-TNG is in December of 2017. This will
make for the official testing of the star camera baffles, and the success of
the experiment is certainly dependent on them. While we will know much
more about the benefits and reproducibility of our star camera baffles after
the experiment has flown, the hope is that this new model for the star
camera baffles will continue to be used for the inevitable future flights
from the BLAST group, and that this design will be adapted and utilized by
other such experiments.
Through experimentation with the aforementioned code, seven baffles were chosen to be placed
at unique spots such that 100% of the unwanted light would be blocked from reaching the star
camera. To demonstrate the accuracy of this, the following plots were generated.
Acknowledgments
This research would not have been possible without the tremendous
assistance of Dr. Mark Devlin, Jeff Klein, Elio Angilè, Federico Nati,
Nicholas Galitzki, Nathan Lourie, and Brad Dober.
The top two plots demonstrate the effectiveness of the star camera baffles without any individual
baffles placed inside of the structure, while the lower two plots demonstrate the effectiveness of
the star camera baffles with the experimentally chosen locations of the seven individual baffles
(note that the center aluminum ring also acts as a baffle). The star camera lens is indicated in the
top left plot via dashed lines, so the fact that no colored beams make it into that region is ideal.
On the bottom right we see an empty plot, meaning that there are no combinations of initial angle
and height from the center entering the star camera baffle which will allow any indices of light to
reach the star camera; again, this is ideal. Overall, these plots shore up any doubt that undesired
photons will be seen by our star cameras during flight. Below are images of the star camera
baffle at various stages of its construction, putting on display all of its various components.
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