Optics/Photonics in Security and Defence最新文献

{"title":"Comparison of flash and accumulation mode in range-gated active imaging","authors":"F. Christnacher, Martin Laurenzis, S. Schertzer","doi":"10.1117/12.2028347","DOIUrl":"https://doi.org/10.1117/12.2028347","url":null,"abstract":"Range-gated active imaging has significantly been improved in the recent past. Due to the availability of high power laser diodes around 800-860 nm, it is now possible to find off-the-shelf systems working with very sensitive light intensifier and laser diodes. On the other hand, eye-safe systems working around 1.5 μm suffer from a lack of intensified sensor in the SWIR band. The only existing intensified sensors require the use of high power pulsed laser sources for the illumination. Consequently, the type of source (diode or solid-state laser) gives fundamental differences between the two types of system. The first technique which uses laser diodes, μchip or fiber lasers, is called \"accumulation\" imaging. These sources are characterized by a low-pulse power and high repetition rate, mostly around a few tens of kHz. Here, each image is the result of the accumulation of hundred of pulses during the frame time. The second technique which uses a solid-state laser illumination is called \"flash\" imaging. Here, each image is the result of a unique high power illumination of the scene at low repetition rate, mostly around the video rate. In this paper, we investigate the theoretical and practical differences between these two imaging modes and its influence on image quality, on sensitivity to day light or stray light, on fog penetration capacity, on its sensitivity to turbulences and on laser safety (NOHD). For comparative experimental purposes, we've built a range-gated active imaging system which allows the investigation of both methods. We've carried out precise comparative studies between the two acquisition methods.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"195 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121613259","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}

{"title":"Image generation for single detector infrared seekers via compressive sensing","authors":"Hande Uzeler, Serdar Çakır, T. Aytaç","doi":"10.1117/12.2030104","DOIUrl":"https://doi.org/10.1117/12.2030104","url":null,"abstract":"In this paper, we investigate the application of compressive sensing theory to single detector infrared seekers. Compressive sensing is a novel signal processing technique which enables a compressible signal to be constructed using fewer measurements obtained in a specific way below the Nyquist rate. Single detector image reconstruction applications using compressive sensing have been shown to be successful. Infrared seekers utilizing single detectors suffer from low performance compared to costly focal plane array detectors. The single detector, pseudo-imaging rosette scanning seekers scan the scene with a specific pattern and process the resultant signal with signal processing methods to estimate the target location without forming an image. In this context, this type of old generation seekers can be converted to imaging systems by utilizing the samples obtained by the scanning pattern in conjunction with the compressive sensing theory framework. In this study, infrared images have been reconstructed from samples obtained by the rosette scanning pattern for different sample numbers and it has been shown that the results obtained are comparable to the results obtained by other sampling methods proposed in the literature.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123979594","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}

{"title":"Patterned resistive sheets for use in infrared microbolometers","authors":"D. Neikirk, Hoo Kim, J. Park, Joo-Yun Jung","doi":"10.1117/12.2029200","DOIUrl":"https://doi.org/10.1117/12.2029200","url":null,"abstract":"We review a wide range of absorbers based on patterned resistive sheets for use in mid-wave and long-wave infrared microbolometers. These structures range from wavelength selective dielectric coated Salisbury screens to patterned resistive sheets to stacked multi-spectral devices. For basic three color devices in the LWIR band we have designed and fabricated wavelength selective dielectric coated Salisbury screen (DSS) absorbers suitable for use in microbolometers. In order to produce wavelength selective narrowband absorption, the general design rules for DSS microbolometers show that the thickness of the air gap should be a half wavelength and the optical thickness of the dielectric support layer should be a quarter wavelength. This structure is also air gap tunable; i.e., by varying only air gap thickness, the center wavelength of the absorption curve is shifted. FTIR microscope measurements have been made on a number of the different devices demonstrating three color capability in the LWIR while maintain very high efficiency absorption. We have also shown that the use of a patterned resistive sheet consisting of a properly sized array of cross-shaped holes acts as a polarization independent frequency-selective absorber allowing a three-color system spanning the 7-14 micron band. For realistic metal layers the skin effect produces complex surface impedance that can be quite large in the LWIR band. We have shown that metal layers of thickness between one and three skin depths can act as the absorber layer, and have shown that thick metal layers can still produce excellent absorption in the LWIR. Holes in the dielectric support layer also reduce the thermal mass in the system without compromising spectral selectivity. Broadband designs using rectangular holes that produce substantially reduced thermal mass (over 50%) while maintaining efficient spectral absorption have also been found. Finally, we have considered multispectral stacked structures, including Jaumann absorbers and stacked dipole/slot patterned resistive sheets. These structures promise either two band (MWIR/LWIR) or two to three color LWIR in a multi-layer stacked pixel.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125416781","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}

{"title":"A Long Wave Infrared (LWIR) spectral imager (7.7 to 12.3 μ) based on cooled detector array and high resolution Circular Variable Filter (CVF)","authors":"D. Cabib, M. Lavi, A. Gil, E. Ohel, Jacob Dolev, Uri Milman","doi":"10.1117/12.2029524","DOIUrl":"https://doi.org/10.1117/12.2029524","url":null,"abstract":"Spectral imagers in the Long Wave IR spectral range (8 to 12 microns) suffer from the problem of high production costs because the existing commercial cooled array detectors are expensive, and in fact they are prohibitively expensive for many applications. As a result, the drive to lower the cost of Long Wave IR spectral imagers is strong: this is the main motivation for CI to investigate a new design that allows these spectral imagers to be more affordable. One area of possible cost reduction without relinquishing the advantages of a cryogenically cooled detector is the method used to provide the spectral information. CI Systems has developed a long wave IR (7.7 to 12.3 micron) spectral imager concept using a Circular Variable Filter (CVF), (a proprietary component based on multiple layer interference filter technology) which has advantages over the interferometric Fourier Transform method commonly used in this spectral range. The CVF method has its own development challenges; however, once proven, this concept may be more suitable and affordable for applications in which a spectral resolution of 0.5% of the wavelength (or 50 nm at 10 μ) is required. The design of the optical system must minimize background signals without being cooled to cryogenic temperatures, so we called it VIrtually COld (or VICO). CI is in the final stages of prototype building and characterization. Present initial calibration results and measurement examples are given in this paper.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114886368","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}

{"title":"Investigation of index of refraction changes in chalcogenide glasses during molding processes","authors":"Jacklyn Novak, R. Pini, W. Moreshead, E. Stover, Alan Symmons","doi":"10.1117/12.2028902","DOIUrl":"https://doi.org/10.1117/12.2028902","url":null,"abstract":"Precision glass molding has a well-documented effect of a decrease in the index of refraction of the glass during the molding process. This index drop has such significant value that optical designs for molded lenses must take into account the index drop to accurately determine the optical performance of the final lens. Widespread adoption of chalcogenide glasses for molded infrared optics has raised a series of questions as to the behavior of these glasses under molding conditions. This paper will investigate the index of refraction changes in two different chalcogenide glasses and determine if these changes are significant enough for optical designers to consider in their designs.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134388115","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}

{"title":"Determining the range parameters of observation thermal cameras on the basis of laboratory measurements","authors":"J. Barela, M. Kastek, K. Firmanty, P. Trzaskawka","doi":"10.1117/12.2028703","DOIUrl":"https://doi.org/10.1117/12.2028703","url":null,"abstract":"Range parameters are main factors in assessing the performance of observation devices. They can be determined on the basis of computer simulations, field or laboratory measurements, with the latter method being the most reliable and practical. The paper presents the methods used for the determination of detection, recognition and identification ranges based on well-known Johnson criteria and recently emerged TTP model. Theoretical background for both approaches are given, and the laboratory test stand is described together with brief methodology adopted for the measurements of selected, necessary characteristics of a tested observation system. The measurement results are presented and the calculated ranges for a selected set of IR cameras are given, obtained on the basis of both Johnson criteria and TTP model. Finally the results are discussed and the final thoughts on the TTP model application are presented.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116983028","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}

{"title":"Design, fabrication, and applications of ultra-narrow infrared bandpass interference filters","authors":"J. Kischkat, Sven Peters, M. Semtsiv, T. Wegner, M. Elagin, G. Monastyrskyi, Y. Flores, S. Kurlov, W. Masselink","doi":"10.1117/12.2029336","DOIUrl":"https://doi.org/10.1117/12.2029336","url":null,"abstract":"We present progress on bandpass infrared interference filters with very narrow passbands to be used for sensitive trace gas and volatile compound imaging and detection and are suitable for mode selection and tuning in singlemode External Cavity Quantum Cascade Lasers. The process parameters for fabrication of such filters with central wavelengths in the 3-12 μm range are described. One representative fillter has a passband width of 6 nm or 0.14% with peak transmission of 62% and a central wavelength of 4.4μm. Theoretically, it can be tuned through about 4% by tilting with respect to the incident beam and offers orders of magnitude larger angular dispersion than diffraction gratings. We compare filters with single-cavity and coupled-cavity Fabry-Perot designs. The filters pass the tests for adhesion and abrasion as stated in MIL-C-48497.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116996242","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}

{"title":"Large format, small pixel pitch and hot detectors at SOFRADIR","authors":"Y. Reibel, A. Rouvié, A. Nedelcu, T. Augey, N. Péré-Laperne, L. Rubaldo, D. Billon-Lanfrey, O. Gravrand, J. Rothman, G. Destefanis","doi":"10.1117/12.2030698","DOIUrl":"https://doi.org/10.1117/12.2030698","url":null,"abstract":"Recently Sofradir joined a very small circle of IR detector manufacturers with expertise every aspect of the cooled and uncooled IR technologies, all under one roof by consolidating all IR technologies available in France. These different technologies are complementary and are used depending of the needs of the applications mainly concerning the detection range needs as well as their ability to detect in bad weather environmental conditions. SNAKE (InGaAs) and SCORPIO LW (MCT) expand Sofradir's line of small pixel pitch TV format IR detectors from the mid-wavelength to the short and long wavelengths. Our dual band MW-LW QWIP detectors (25μm, 384×288 pixels) benefit to tactical platforms giving an all-weather performance and increasing flexibility in the presence of battlefield obscurants. In parallel we have been pursuing further infrared developments on future MWIR detectors, such as the VGA format HOT detector that consumes 2W and the 10μm pitch IR detector which gives us a leading position in innovation. These detectors are designed for long-range surveillance equipment, commander or gunner sights, ground-to-ground missile launchers and other applications that require higher resolution and sensitivity to improve reconnaissance and target identification. This paper discusses the system level performance in each detector type.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115806239","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}

{"title":"Advanced range imaging with gated viewing: compressed sensing and coding of range gates","authors":"Martin Laurenzis, E. Bacher, S. Schertzer, F. Christnacher","doi":"10.1117/12.2028354","DOIUrl":"https://doi.org/10.1117/12.2028354","url":null,"abstract":"Laser Gated-Viewing Advanced Range Imaging (LGVARI) methods sample range information in a wide range area with super-resolution from a few sampling points. In this paper three different methods are investigated: the Coding of Range- Gates, the Compressed Sensing Range Imaging and a hybrid method of the aforementioned LGVARI methods. In contrast to classical range imaging methods based on Nyquist sampling, the range information is not directly visible in the single images and has to be extracted from a complete sequence by means of computational optics. With LGVARI it is possible to sample range information from only a few sampling points (i.e. images) with super-resolution far beyond the limit of the Nyquist sampling theorem. It is shown that the three methods have a compression rate of < 5%.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"8896 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129851989","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}

{"title":"Image quality testing of assembled IR camera modules","authors":"D. Winters, P. Erichsen","doi":"10.1117/12.2029541","DOIUrl":"https://doi.org/10.1117/12.2029541","url":null,"abstract":"Infrared (IR) camera modules for the LWIR (8-12_m) that combine IR imaging optics with microbolometer focal plane array (FPA) sensors with readout electronics are becoming more and more a mass market product. At the same time, steady improvements in sensor resolution in the higher priced markets raise the requirement for imaging performance of objectives and the proper alignment between objective and FPA. This puts pressure on camera manufacturers and system integrators to assess the image quality of finished camera modules in a cost-efficient and automated way for quality control or during end-of-line testing. In this paper we present recent development work done in the field of image quality testing of IR camera modules. This technology provides a wealth of additional information in contrast to the more traditional test methods like minimum resolvable temperature difference (MRTD) which give only a subjective overall test result. Parameters that can be measured are image quality via the modulation transfer function (MTF) for broadband or with various bandpass filters on- and off-axis and optical parameters like e.g. effective focal length (EFL) and distortion. If the camera module allows for refocusing the optics, additional parameters like best focus plane, image plane tilt, auto-focus quality, chief ray angle etc. can be characterized. Additionally, the homogeneity and response of the sensor with the optics can be characterized in order to calculate the appropriate tables for non-uniformity correction (NUC). The technology can also be used to control active alignment methods during mechanical assembly of optics to high resolution sensors. Other important points that are discussed are the flexibility of the technology to test IR modules with different form factors, electrical interfaces and last but not least the suitability for fully automated measurements in mass production.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123191634","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}