A. Mandal, H. Ghadi, Goma Kumari K. C., A. Basu, N. Subrahmanyam, P. Singh, S. Chakrabarti
Considering the importance of In(Ga)As/GaAs QDIPs, a post-growth method had been developed for enhancing QDIP characteristics using low energy light ion (H-) implantation. Dark current density was reduced by about five orders for the implanted devices due to the reduction in field assisted tunneling process for dark current generation, even at a very high bias of operation. Stronger multicolor mid wavelength photo response (~5.6 µm) was achieved at a very low bias of operation for the implanted device.
{"title":"Reduction of dark current density by five orders at high bias and enhanced multicolour photo response at low bias for quaternary alloy capped InGaAs/ GaAs QDIPs, when implanted with low-energy light (H-) ions","authors":"A. Mandal, H. Ghadi, Goma Kumari K. C., A. Basu, N. Subrahmanyam, P. Singh, S. Chakrabarti","doi":"10.1117/12.2016299","DOIUrl":"https://doi.org/10.1117/12.2016299","url":null,"abstract":"Considering the importance of In(Ga)As/GaAs QDIPs, a post-growth method had been developed for enhancing QDIP characteristics using low energy light ion (H-) implantation. Dark current density was reduced by about five orders for the implanted devices due to the reduction in field assisted tunneling process for dark current generation, even at a very high bias of operation. Stronger multicolor mid wavelength photo response (~5.6 µm) was achieved at a very low bias of operation for the implanted device.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124087970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. George, Bin Wang, R. Petrova, Hua Li, J. Bergquist
High contrast wire grid polarizers on silicon suitable for mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) applications have been developed using wafer-scale aluminum nanowire patterning capabilities. The 144 nm pitch MWIR polarizer typically transmits better than 95% of the passing polarization state from 3.5-5.5 microns while maintaining a contrast ratio of better than 37dB. Between 7 and 15 microns, the broadband LWIR polarizer typically transmits between 55 and 90% of the passing state and has a contrast ratio better than 40 dB. A narrowband 10.6 micron polarizer shows about 85% transmission in the passing state and a contrast ratio of 45 dB. Transmission and reflection measurements were made using various FTIR spectrometers and compared to RCWA modeling of the wire grid polarizer (WGP) performance on antireflection-coated wafers. Laser Damage Threshold (LDT) testing was performed using a continuous wave CO2 laser for the broadband LWIR product and showed a damage threshold of 110 kW/cm2 in the blocking state and 10 kW/cm2 in the passing state. The MWIR LDT testing used an OPO operating at 4 microns with 7 ns pulses and showed LDT of 650 W/cm2 in the blocking state and better than 14 kW/cm2 in the passing state
{"title":"Nanowire grid polarizers for mid- and long-wavelength infrared applications","authors":"M. George, Bin Wang, R. Petrova, Hua Li, J. Bergquist","doi":"10.1117/12.2016221","DOIUrl":"https://doi.org/10.1117/12.2016221","url":null,"abstract":"High contrast wire grid polarizers on silicon suitable for mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) applications have been developed using wafer-scale aluminum nanowire patterning capabilities. The 144 nm pitch MWIR polarizer typically transmits better than 95% of the passing polarization state from 3.5-5.5 microns while maintaining a contrast ratio of better than 37dB. Between 7 and 15 microns, the broadband LWIR polarizer typically transmits between 55 and 90% of the passing state and has a contrast ratio better than 40 dB. A narrowband 10.6 micron polarizer shows about 85% transmission in the passing state and a contrast ratio of 45 dB. Transmission and reflection measurements were made using various FTIR spectrometers and compared to RCWA modeling of the wire grid polarizer (WGP) performance on antireflection-coated wafers. Laser Damage Threshold (LDT) testing was performed using a continuous wave CO2 laser for the broadband LWIR product and showed a damage threshold of 110 kW/cm2 in the blocking state and 10 kW/cm2 in the passing state. The MWIR LDT testing used an OPO operating at 4 microns with 7 ns pulses and showed LDT of 650 W/cm2 in the blocking state and better than 14 kW/cm2 in the passing state","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132737837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Sakat, G. Vincent, S. Rommeluère, C. Eradès, S. Lefebvre, F. Cauty, S. Collin, G. Druart, J. Pelouard, R. Haïdar
We present a compact real-time multispectral camera operating in the mid-infrared wavelength range. Multispectral images of a scene with two differently spectrally signed objects and of a burning solid propellant will be shown. Ability of real-time acquisition will thus be demonstrated and spectra of objects will be retrieved thanks to inversion algorithm applied on multispectral images.
{"title":"Analysis of propellant combustion with real-time multispectral infrared camera","authors":"E. Sakat, G. Vincent, S. Rommeluère, C. Eradès, S. Lefebvre, F. Cauty, S. Collin, G. Druart, J. Pelouard, R. Haïdar","doi":"10.1117/12.2015835","DOIUrl":"https://doi.org/10.1117/12.2015835","url":null,"abstract":"We present a compact real-time multispectral camera operating in the mid-infrared wavelength range. Multispectral images of a scene with two differently spectrally signed objects and of a burning solid propellant will be shown. Ability of real-time acquisition will thus be demonstrated and spectra of objects will be retrieved thanks to inversion algorithm applied on multispectral images.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"8704 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129760084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Montoya, S. Myers, A. Barve, J. Kim, S. Krishna, D. Peters, C. Reinke, J. Wendt
Current infrared imaging systems monitor emission from a given scene over a broad spectral range, which results with "black and white" images. As a result, there is ever increasing emphasis on the development of new, on the pixel level, infrared imaging technology that can provide spectral information. Attempts at creating a robust imaging system with spectral information have been made through a network of external optics, which results with a high cost and large system package. Here, we propose a metamaterial design that resonantly couples to an infrared photodetector for enhanced performance.
{"title":"Broadband enhancement of infrared photodetectors with metamaterial resonators","authors":"J. Montoya, S. Myers, A. Barve, J. Kim, S. Krishna, D. Peters, C. Reinke, J. Wendt","doi":"10.1117/12.2018198","DOIUrl":"https://doi.org/10.1117/12.2018198","url":null,"abstract":"Current infrared imaging systems monitor emission from a given scene over a broad spectral range, which results with \"black and white\" images. As a result, there is ever increasing emphasis on the development of new, on the pixel level, infrared imaging technology that can provide spectral information. Attempts at creating a robust imaging system with spectral information have been made through a network of external optics, which results with a high cost and large system package. Here, we propose a metamaterial design that resonantly couples to an infrared photodetector for enhanced performance.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130854688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Selex ES present progress on their FALCON HD1920x1080p 12μm pitch MWIR array. FALCON is buttable on 3- sides, enabling close packed mosaic arrays to be implemented. An update on FALCON array test results, progress on megapixel mosaic array development and HOT MCT is given.
{"title":"16 megapixel 12μm array developments at Selex ES","authors":"P. Thorne, J. Gordon, L. Hipwood, A. Bradford","doi":"10.1117/12.2015886","DOIUrl":"https://doi.org/10.1117/12.2015886","url":null,"abstract":"Selex ES present progress on their FALCON HD1920x1080p 12μm pitch MWIR array. FALCON is buttable on 3- sides, enabling close packed mosaic arrays to be implemented. An update on FALCON array test results, progress on megapixel mosaic array development and HOT MCT is given.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125321469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Druart, F. de la Barrière, M. Chambon, N. Guerineau, G. Lasfargues, M. Fendler
We present a compact infrared cryogenic multichannel camera with a wide field of view equal to 120°. By merging the optics with the detector, the concept has to be compatible with both cryogenic constraints and wafer-level fabrication. For this, we take advantage of the progress in micro-optics to design a multichannel optical architecture directly integrated on the detector. This wafer-level camera uses state of art microlenses with a high sag height. The additional mass of the optics is sufficiently small to be compatible with the cryogenic environment of the Dewar. The performance of this camera will be discussed. Its characterization has been carried out in terms of modulation transfer function and noise equivalent temperature difference (NETD). The optical system is limited by the diffraction. By cooling the optics, we achieve a very low NETD equal to 15 mK compared with traditional infrared cameras. A postprocessing algorithm that aims at reconstructing a well-sampled image from the set of undersampled raw subimages produced by the camera is proposed and validated on experimental images.
{"title":"Cryogenic wafer-level MWIR camera: laboratory demonstration","authors":"G. Druart, F. de la Barrière, M. Chambon, N. Guerineau, G. Lasfargues, M. Fendler","doi":"10.1117/12.2016371","DOIUrl":"https://doi.org/10.1117/12.2016371","url":null,"abstract":"We present a compact infrared cryogenic multichannel camera with a wide field of view equal to 120°. By merging the optics with the detector, the concept has to be compatible with both cryogenic constraints and wafer-level fabrication. For this, we take advantage of the progress in micro-optics to design a multichannel optical architecture directly integrated on the detector. This wafer-level camera uses state of art microlenses with a high sag height. The additional mass of the optics is sufficiently small to be compatible with the cryogenic environment of the Dewar. The performance of this camera will be discussed. Its characterization has been carried out in terms of modulation transfer function and noise equivalent temperature difference (NETD). The optical system is limited by the diffraction. By cooling the optics, we achieve a very low NETD equal to 15 mK compared with traditional infrared cameras. A postprocessing algorithm that aims at reconstructing a well-sampled image from the set of undersampled raw subimages produced by the camera is proposed and validated on experimental images.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123796406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
InAsSb ternary alloy is potentially capable of operating at the longest cut-off wavelength (about 9 μm at 77 K) in the entire III-V family. Recently, there has been a considerable progress in development of the InAsSb focal plane arrays. The high operation temperature conditions were successfully achieved with AIIIBV unipolar barrier structures including InAsSb/AlAsSb material system. In this paper, the performance of medium wavelength infrared (MWIR) InAsSb-based nBnnn+ detectors, called also "bariodes", is examined theoretically taking into account thermal generation governed by the Auger and radiative mechanisms. In our model, the heterojunction barrier-active region (absorber) is assumed to be decisive as the contributing dark current mechanism limiting detector's performance. Since there is no depletion layer in the active layer of such devices, generation-recombination and trap assisted tunneling mechanisms are suppressed leading to lower dark currents in bariode detectors in comparison to standard diodes. Detailed analysis of the detector’s performance (such as dark current, RA product, and current responsivity) versus bias voltage and operating temperatures are performed pointing out optimal working conditions. The theoretical predictions of bariode parameters are compared with experimental data published in the literature. Finally, the bariode performance is compared with standard p+-on-n InAsSb photodiodes operated at room temperature with the same bandgap wavelength.
{"title":"Modeling of InAsSb/AlAsSb nBn HOT detector's performance limit","authors":"P. Martyniuk, A. Rogalski","doi":"10.1117/12.2017721","DOIUrl":"https://doi.org/10.1117/12.2017721","url":null,"abstract":"InAsSb ternary alloy is potentially capable of operating at the longest cut-off wavelength (about 9 μm at 77 K) in the entire III-V family. Recently, there has been a considerable progress in development of the InAsSb focal plane arrays. The high operation temperature conditions were successfully achieved with AIIIBV unipolar barrier structures including InAsSb/AlAsSb material system. In this paper, the performance of medium wavelength infrared (MWIR) InAsSb-based nBnnn+ detectors, called also \"bariodes\", is examined theoretically taking into account thermal generation governed by the Auger and radiative mechanisms. In our model, the heterojunction barrier-active region (absorber) is assumed to be decisive as the contributing dark current mechanism limiting detector's performance. Since there is no depletion layer in the active layer of such devices, generation-recombination and trap assisted tunneling mechanisms are suppressed leading to lower dark currents in bariode detectors in comparison to standard diodes. Detailed analysis of the detector’s performance (such as dark current, RA product, and current responsivity) versus bias voltage and operating temperatures are performed pointing out optimal working conditions. The theoretical predictions of bariode parameters are compared with experimental data published in the literature. Finally, the bariode performance is compared with standard p+-on-n InAsSb photodiodes operated at room temperature with the same bandgap wavelength.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"8704 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130128552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Torres, J. Ganley, A. Maji, D. Tucker, D. Starodubov
Fluorozirconate glasses, such as ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF), have the potential for optical transmission from 0.3 μm in the UV to 7 μm in the IR region. However, crystallites formed during the fiber drawing process prevent this glass from achieving its desired transmission range. The temperature at which the glass can be drawn into a fiber is known as the working range, defined as (Tx - Tg), bounded by the glass transition temperature (Tg) and the crystallization temperature (Tx). In contrast to silica glasses, the working temperature range for ZBLAN glass is extremely narrow. Multiple ZBLAN samples were subject to a heating and quenching test apparatus on the parabolic aircraft, under a controlled 0-g and hyper-g environment and compared with 1-g ground tests. The microgravity duration on board Zero-G Corporation parabolic aircraft is approximately 20 seconds and the hyper-g intervals are approximately 56 seconds. Optical microscopy examination elucidates crystal growth in ZBLAN is suppressed when processed in a microgravity environment. The crystallization temperature, Tx, at which crystals form increased, therefore, significantly broadening the working temperature range for ZBLAN.
{"title":"Enhanced processability of ZrF4-BaF2-LaF3-AlF3-NaF glass in microgravity","authors":"A. Torres, J. Ganley, A. Maji, D. Tucker, D. Starodubov","doi":"10.1117/12.2018308","DOIUrl":"https://doi.org/10.1117/12.2018308","url":null,"abstract":"Fluorozirconate glasses, such as ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF), have the potential for optical transmission from 0.3 μm in the UV to 7 μm in the IR region. However, crystallites formed during the fiber drawing process prevent this glass from achieving its desired transmission range. The temperature at which the glass can be drawn into a fiber is known as the working range, defined as (Tx - Tg), bounded by the glass transition temperature (Tg) and the crystallization temperature (Tx). In contrast to silica glasses, the working temperature range for ZBLAN glass is extremely narrow. Multiple ZBLAN samples were subject to a heating and quenching test apparatus on the parabolic aircraft, under a controlled 0-g and hyper-g environment and compared with 1-g ground tests. The microgravity duration on board Zero-G Corporation parabolic aircraft is approximately 20 seconds and the hyper-g intervals are approximately 56 seconds. Optical microscopy examination elucidates crystal growth in ZBLAN is suppressed when processed in a microgravity environment. The crystallization temperature, Tx, at which crystals form increased, therefore, significantly broadening the working temperature range for ZBLAN.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123727766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In uncooled LWIR microbolometer imaging systems, temperature fluctuations of FPA (Focal Plane Array) as well as lens and mechanical components placed along the optical path result in thermal drift and spatial non-uniformity. These non-idealities generate undesirable FPN (Fixed-Pattern-Noise) that is difficult to remove using traditional, individual shutterless and TEC-less (Thermo-Electric Cooling) techniques. In this paper we introduce a novel single-image based processing approach that marries the benefits of both statistical scene-based and calibration-based NUC algorithms, without relying neither on extra temperature reference nor accurate motion estimation, to compensate the resulting temperature-dependent non-uniformities. Our method includes two subsequent image processing steps. Firstly, an empirical behavioral model is derived by calibrations to characterize the spatio-temporal response of the microbolometric FPA to environmental and scene temperature fluctuations. Secondly, we experimentally establish that the FPN component caused by the optics creates a spatio-temporally continuous, low frequency, low-magnitude variation of the image intensity. We propose to make use of this property and learn a prior on the spatial distribution of natural image gradients to infer the correction function for the entire image. The performance and robustness of the proposed temperature-adaptive NUC method are demonstrated by showing results obtained from a 640×512 pixels uncooled LWIR microbolometer imaging system operating over a broad range of temperature and with rapid environmental temperature changes (i.e. from –5°C to 65°C within 10 minutes).
{"title":"Solid state temperature-dependent NUC (non-uniformity correction) in uncooled LWIR (long-wave infrared) imaging system","authors":"Yanpeng Cao, C. Tisse","doi":"10.1117/12.2015641","DOIUrl":"https://doi.org/10.1117/12.2015641","url":null,"abstract":"In uncooled LWIR microbolometer imaging systems, temperature fluctuations of FPA (Focal Plane Array) as well as lens and mechanical components placed along the optical path result in thermal drift and spatial non-uniformity. These non-idealities generate undesirable FPN (Fixed-Pattern-Noise) that is difficult to remove using traditional, individual shutterless and TEC-less (Thermo-Electric Cooling) techniques. In this paper we introduce a novel single-image based processing approach that marries the benefits of both statistical scene-based and calibration-based NUC algorithms, without relying neither on extra temperature reference nor accurate motion estimation, to compensate the resulting temperature-dependent non-uniformities. Our method includes two subsequent image processing steps. Firstly, an empirical behavioral model is derived by calibrations to characterize the spatio-temporal response of the microbolometric FPA to environmental and scene temperature fluctuations. Secondly, we experimentally establish that the FPN component caused by the optics creates a spatio-temporally continuous, low frequency, low-magnitude variation of the image intensity. We propose to make use of this property and learn a prior on the spatial distribution of natural image gradients to infer the correction function for the entire image. The performance and robustness of the proposed temperature-adaptive NUC method are demonstrated by showing results obtained from a 640×512 pixels uncooled LWIR microbolometer imaging system operating over a broad range of temperature and with rapid environmental temperature changes (i.e. from –5°C to 65°C within 10 minutes).","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114957299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Bayya, J. Sanghera, Woohong Kim, D. Gibson, E. Fleet, B. Shaw, M. Hunt, I. Aggarwal
We report new multispectral materials that transmit from 0.9 to < 12 µm in wavelength. These materials fill up the glass map for multispectral optics and vary in refractive index from 2.38 to 3.17. They show a large spread in dispersion (Abbe number) and offer some unique solutions for multispectral optics designs. One of the glasses developed is a very good candidate to replace Ge, as it has a combination of excellent properties, including high Abbe number in the LWIR, high index of 3.2, 60% lower dn/dT, and better thermal stability at working temperatures. Our results also provide a wider selection of optical materials to enable simpler achromat designs. For example, we have developed other glasses that have relatively high Abbe number in both the MWIR and LWIR regions, while our MILTRAN ceramic has low Abbe number in both regions. This makes for a very good combination of glasses and MILTRAN ceramic (analogous to crown and flint glasses in the visible) for MWIR + LWIR dual band imaging. We have designed preliminary optics for one such imager with f/2.5, 51 mm focal length and 22 degrees FOV using a spaced doublet of NRL's glass and MILTRAN ceramic. NRL's approach reduces the number of elements, weight, complexity and cost compared with the approach using traditional optics. Another important advantage of using NRL glasses in optics design is their negative or very low positive dn/dT, that makes it easier to athermalize the optical system.
{"title":"New multiband IR imaging optics","authors":"S. Bayya, J. Sanghera, Woohong Kim, D. Gibson, E. Fleet, B. Shaw, M. Hunt, I. Aggarwal","doi":"10.1117/12.2016332","DOIUrl":"https://doi.org/10.1117/12.2016332","url":null,"abstract":"We report new multispectral materials that transmit from 0.9 to < 12 µm in wavelength. These materials fill up the glass map for multispectral optics and vary in refractive index from 2.38 to 3.17. They show a large spread in dispersion (Abbe number) and offer some unique solutions for multispectral optics designs. One of the glasses developed is a very good candidate to replace Ge, as it has a combination of excellent properties, including high Abbe number in the LWIR, high index of 3.2, 60% lower dn/dT, and better thermal stability at working temperatures. Our results also provide a wider selection of optical materials to enable simpler achromat designs. For example, we have developed other glasses that have relatively high Abbe number in both the MWIR and LWIR regions, while our MILTRAN ceramic has low Abbe number in both regions. This makes for a very good combination of glasses and MILTRAN ceramic (analogous to crown and flint glasses in the visible) for MWIR + LWIR dual band imaging. We have designed preliminary optics for one such imager with f/2.5, 51 mm focal length and 22 degrees FOV using a spaced doublet of NRL's glass and MILTRAN ceramic. NRL's approach reduces the number of elements, weight, complexity and cost compared with the approach using traditional optics. Another important advantage of using NRL glasses in optics design is their negative or very low positive dn/dT, that makes it easier to athermalize the optical system.","PeriodicalId":338283,"journal":{"name":"Defense, Security, and Sensing","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133408395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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