A point cloud can provide a detailed three dimensional (3D) description of a scene. Partitioning of a point cloud into semantic classes is important for scene understanding, which can be used in autonomous navigation for unmanned vehicles and in applications including surveillance, mapping, and reconnaissance. In this paper, we give a review of recent machine learning techniques for semantic segmentation of point clouds from scanning lidars and an overview of model compression techniques. We focus especially on scan-based learning approaches, which operate on single sensor sweeps. These methods do not require data registration and are suitable for real-time applications. We demonstrate how these semantic segmentation techniques can be used in defence applications in surveillance or mapping scenarios with a scanning lidar mounted on a small UAV.
{"title":"Semantic segmentation of point clouds from scanning lidars","authors":"Maria Axelsson, M. Holmberg, M. Tulldahl","doi":"10.1117/12.2645181","DOIUrl":"https://doi.org/10.1117/12.2645181","url":null,"abstract":"A point cloud can provide a detailed three dimensional (3D) description of a scene. Partitioning of a point cloud into semantic classes is important for scene understanding, which can be used in autonomous navigation for unmanned vehicles and in applications including surveillance, mapping, and reconnaissance. In this paper, we give a review of recent machine learning techniques for semantic segmentation of point clouds from scanning lidars and an overview of model compression techniques. We focus especially on scan-based learning approaches, which operate on single sensor sweeps. These methods do not require data registration and are suitable for real-time applications. We demonstrate how these semantic segmentation techniques can be used in defence applications in surveillance or mapping scenarios with a scanning lidar mounted on a small UAV.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"149 1","pages":"1227206 - 1227206-9"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77492384","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}
We developed a compact, diode-end-pumped, eye-safe laser rangefinder transmitter, which is based on the passively Q-switched Er–Yb:glass laser with a Co:Spinel plate as a saturable absorber (SA). The linear cavity laser considers a concave and a plane mirror with the cavity length is only 20 mm. The repetition rate can be tuned from 1 Hz to 8 Hz at the wavelength of 1535 nm. Our laser system operates stably at peak power > 250 kW and pulse width of 4.5 ns.
{"title":"Compact, diode end-pumped, eye-safe laser rangefinder transmitter","authors":"V. Vu, Tuan A. Nguyen, M. Tran, Bao-Dong To","doi":"10.1117/12.2638473","DOIUrl":"https://doi.org/10.1117/12.2638473","url":null,"abstract":"We developed a compact, diode-end-pumped, eye-safe laser rangefinder transmitter, which is based on the passively Q-switched Er–Yb:glass laser with a Co:Spinel plate as a saturable absorber (SA). The linear cavity laser considers a concave and a plane mirror with the cavity length is only 20 mm. The repetition rate can be tuned from 1 Hz to 8 Hz at the wavelength of 1535 nm. Our laser system operates stably at peak power > 250 kW and pulse width of 4.5 ns.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"29 1","pages":"122730I - 122730I-6"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80949080","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}
One of the most prominent applications of fiber optic Distributed Acoustic Sensing (DAS) is Perimeter Security via fence monitoring, which is possible when we attach a fiber to the fence. In this study, we aim to detect and classify events occurring around said fence, such as climbing, cutting, and bending. For this, we investigate Deep Learning algorithms, more specifically Convolutional Neural Networks (CNN), as a mean to detect anomalies and classify them. We recorded 48,445 samples of the mentioned events, which were carefully processed and labeled. From each record, we exploited multiple data instances, resulting in a large enough training dataset to produce a robust classifier. We report the optimum network architecture that suited our study for both the anomaly detection and classification task. The optimal model is tested before and after deployment on-site, we report the quantified performance on a test set via a confusion matrix, and observations about the model’s behaviour on the field. Furthermore, we compare our trials and results on two types of fences, namely rigid and loose, to show how it affects the performance of the trained CNN models, as the signal propagates differently between rigid and loose clotures. We report an overall accuracy of 96.15% for the optimal anomaly detection model, and a lower 52.9% for the 3-class classification model. These results are explained and commented on. Finally, we conclude by providing an educated proposal for future improvements.
{"title":"Distributed acoustic sensing for fence monitoring: deep learning approach for detection and classification of events on various types of fence","authors":"Billel Alla Eddine Bencharif, Tayfun Erkorkmaz","doi":"10.1117/12.2638480","DOIUrl":"https://doi.org/10.1117/12.2638480","url":null,"abstract":"One of the most prominent applications of fiber optic Distributed Acoustic Sensing (DAS) is Perimeter Security via fence monitoring, which is possible when we attach a fiber to the fence. In this study, we aim to detect and classify events occurring around said fence, such as climbing, cutting, and bending. For this, we investigate Deep Learning algorithms, more specifically Convolutional Neural Networks (CNN), as a mean to detect anomalies and classify them. We recorded 48,445 samples of the mentioned events, which were carefully processed and labeled. From each record, we exploited multiple data instances, resulting in a large enough training dataset to produce a robust classifier. We report the optimum network architecture that suited our study for both the anomaly detection and classification task. The optimal model is tested before and after deployment on-site, we report the quantified performance on a test set via a confusion matrix, and observations about the model’s behaviour on the field. Furthermore, we compare our trials and results on two types of fences, namely rigid and loose, to show how it affects the performance of the trained CNN models, as the signal propagates differently between rigid and loose clotures. We report an overall accuracy of 96.15% for the optimal anomaly detection model, and a lower 52.9% for the 3-class classification model. These results are explained and commented on. Finally, we conclude by providing an educated proposal for future improvements.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"38 1","pages":"1227205 - 1227205-9"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82491768","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}
Andreas Peckhaus, Fabian Elsässer, T. Hall, F. Duschek
The accurate quantification of scattered laser radiation is crucial for estimating threats to humans from outdoor applications of high-power lasers. In addition to the hazard due to intrabeam viewing, specular and diffuse reflections from irradiated targets can potentially harm the human eye and skin. Measurement techniques for the detection of scattered laser radiation have been developed in the way to provide quantitative information for advanced analyses as well as proofs and further improvements of laser safety calculations. The detection system has to be calibrated, characterized and validated in order to obtain reliable results. A compact and wavelength-specific detection system is presented, which relies on the technical specifications (i.e. entrance aperture and angular field) according to German laser safety policies. The mobile detection system is deployed at the DLR laser test range in Lampoldshausen (Germany). Field measurements are performed by irradiating metallic targets with high-power laser radiation at 1030 nm and simultaneously measuring the scattered laser radiation with the calibrated detection system. The field of view of the detection system is oriented to the target by using an alignment laser integrated into the detection system. Target samples with different surface roughness are examined in the experiments to analyze specularly and diffusely scattered laser radiation. The dependence of the scattering angle and the distance from the metallic targets to the detection system are investigated. The results are compared to threshold limits of laser safety standards.
{"title":"Field validation of a mobile detection system for laser scattering measurements in the NIR range","authors":"Andreas Peckhaus, Fabian Elsässer, T. Hall, F. Duschek","doi":"10.1117/12.2636087","DOIUrl":"https://doi.org/10.1117/12.2636087","url":null,"abstract":"The accurate quantification of scattered laser radiation is crucial for estimating threats to humans from outdoor applications of high-power lasers. In addition to the hazard due to intrabeam viewing, specular and diffuse reflections from irradiated targets can potentially harm the human eye and skin. Measurement techniques for the detection of scattered laser radiation have been developed in the way to provide quantitative information for advanced analyses as well as proofs and further improvements of laser safety calculations. The detection system has to be calibrated, characterized and validated in order to obtain reliable results. A compact and wavelength-specific detection system is presented, which relies on the technical specifications (i.e. entrance aperture and angular field) according to German laser safety policies. The mobile detection system is deployed at the DLR laser test range in Lampoldshausen (Germany). Field measurements are performed by irradiating metallic targets with high-power laser radiation at 1030 nm and simultaneously measuring the scattered laser radiation with the calibrated detection system. The field of view of the detection system is oriented to the target by using an alignment laser integrated into the detection system. Target samples with different surface roughness are examined in the experiments to analyze specularly and diffusely scattered laser radiation. The dependence of the scattering angle and the distance from the metallic targets to the detection system are investigated. The results are compared to threshold limits of laser safety standards.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"26 1","pages":"122710D - 122710D-8"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85321665","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}
Aviation is exceptionally vulnerable to man-portable missile attacks (MANPADS), particularly during the critical stages of flight, e.g., take-off and landing. Consequently, aircraft require a further means of self-protection in addition to pyrotechnic flares. Laser Directed Infrared Countermeasures (DIRCM) target the infrared guidance system present in the majority of all MANPADS, resulting in sensor dazzle and possible damage-a soft kill approach. Unfortunately, current DIRCM systems, albeit highly effective against first and second-generation seekers, are less against imaging ones (third and fourth-generation). Our paper investigates a means to increase the effectiveness of dazzle by modulating the laser at a rate close to the frame rate of the imaging sensor, i.e., a strobing effect. A continuous-wave quantum cascade laser (QCL) at 4.6 microns illuminated a mid-infrared focal plane array imager, modulated by either an optical chopper or by periodically varying the current of the QCL. The laser beam and a representative target were combined optically using plano and off-axis parabolic mirrors, resulting in the imager viewing a dazzled scene at infinity. In summary, we demonstrate experimentally that the intermittency of the laser dazzle could improve the effectiveness of a DIRCM system.
{"title":"The effectiveness of amplitude modulation on the laser dazzling of a mid-infrared imager","authors":"G. Lewis, Robbie Struyve, C. Boeckx, M. Vandewal","doi":"10.1117/12.2635447","DOIUrl":"https://doi.org/10.1117/12.2635447","url":null,"abstract":"Aviation is exceptionally vulnerable to man-portable missile attacks (MANPADS), particularly during the critical stages of flight, e.g., take-off and landing. Consequently, aircraft require a further means of self-protection in addition to pyrotechnic flares. Laser Directed Infrared Countermeasures (DIRCM) target the infrared guidance system present in the majority of all MANPADS, resulting in sensor dazzle and possible damage-a soft kill approach. Unfortunately, current DIRCM systems, albeit highly effective against first and second-generation seekers, are less against imaging ones (third and fourth-generation). Our paper investigates a means to increase the effectiveness of dazzle by modulating the laser at a rate close to the frame rate of the imaging sensor, i.e., a strobing effect. A continuous-wave quantum cascade laser (QCL) at 4.6 microns illuminated a mid-infrared focal plane array imager, modulated by either an optical chopper or by periodically varying the current of the QCL. The laser beam and a representative target were combined optically using plano and off-axis parabolic mirrors, resulting in the imager viewing a dazzled scene at infinity. In summary, we demonstrate experimentally that the intermittency of the laser dazzle could improve the effectiveness of a DIRCM system.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"8 1","pages":"122730J - 122730J-18"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90513527","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}
B. Steward, Bret M. Wagner, K. Hopkinson, Shannon R. Young
The AFIT Sensor and Scene Emulation Tool (ASSET) is a physics-based model used to generate synthetic data sets of wide field-of-view (WFOV) electro-optical and infrared (EO/IR) sensors with realistic radiometric properties, noise characteristics, and sensor artifacts. This effort evaluates the use of Convolutional Neural Networks (CNNS) trained on samples of real space-based hyperspectral data paired with panchromatic imagery as a method of generating synthetic hyperspectral reflectance data from wide-band imagery inputs to improve the radiometric accuracy of ASSET. Further, the effort demonstrates how these updates will improve ASSET’s radiometric accuracy through comparisons to NASA’s moderate resolution imaging spectroradiometer (MODIS). In order to place the development of synthetic hyperspectral reflectance data in context, the scene generation process implemented in ASSET is also presented in detail.
{"title":"Modeling EO/IR systems with ASSET: applied machine learning for synthetic WFOV background signature generation","authors":"B. Steward, Bret M. Wagner, K. Hopkinson, Shannon R. Young","doi":"10.1117/12.2638487","DOIUrl":"https://doi.org/10.1117/12.2638487","url":null,"abstract":"The AFIT Sensor and Scene Emulation Tool (ASSET) is a physics-based model used to generate synthetic data sets of wide field-of-view (WFOV) electro-optical and infrared (EO/IR) sensors with realistic radiometric properties, noise characteristics, and sensor artifacts. This effort evaluates the use of Convolutional Neural Networks (CNNS) trained on samples of real space-based hyperspectral data paired with panchromatic imagery as a method of generating synthetic hyperspectral reflectance data from wide-band imagery inputs to improve the radiometric accuracy of ASSET. Further, the effort demonstrates how these updates will improve ASSET’s radiometric accuracy through comparisons to NASA’s moderate resolution imaging spectroradiometer (MODIS). In order to place the development of synthetic hyperspectral reflectance data in context, the scene generation process implemented in ASSET is also presented in detail.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"9 1","pages":"122710B - 122710B-19"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90633560","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}
To create a complete virtual scene with sufficient fidelity so it can be used for signature/camouflage assessment turns out to be complicated. Small differences in scene parameters can have a huge impact on the outcome and parameters are often unknown, which makes comparison with real environments/scenes difficult. Instead of fully virtual scenes we explore ‘hybrid’ or ‘composite’ methods in which a virtual target is simulated in the context of recorded imagery. It turns out that such techniques can generate highly realistic scenes. Here, we explored and compared various methods to create a virtual target: i) small physical models of the target, ii) Material Capture (matcap) in which a probe sphere is recorded in the scene and iii) light field measurements in combination with BRDF. Alongside the virtual target we collect images of the real target in field trials to be used for comparison and evaluation. We discuss the results and compare the different methods. Certain methods seem more applicable to derive a robust measure of the signature of a given target (e.g. the physical model and ‘matcap’), while others seem more appropriate for deriving and testing new camouflage designs and concepts (e.g. light field method).
{"title":"Hybrid simulation for creating realistic scenes for signature assessment","authors":"Koen van der Sanden, M. Hogervorst, P. Bijl","doi":"10.1117/12.2638886","DOIUrl":"https://doi.org/10.1117/12.2638886","url":null,"abstract":"To create a complete virtual scene with sufficient fidelity so it can be used for signature/camouflage assessment turns out to be complicated. Small differences in scene parameters can have a huge impact on the outcome and parameters are often unknown, which makes comparison with real environments/scenes difficult. Instead of fully virtual scenes we explore ‘hybrid’ or ‘composite’ methods in which a virtual target is simulated in the context of recorded imagery. It turns out that such techniques can generate highly realistic scenes. Here, we explored and compared various methods to create a virtual target: i) small physical models of the target, ii) Material Capture (matcap) in which a probe sphere is recorded in the scene and iii) light field measurements in combination with BRDF. Alongside the virtual target we collect images of the real target in field trials to be used for comparison and evaluation. We discuss the results and compare the different methods. Certain methods seem more applicable to derive a robust measure of the signature of a given target (e.g. the physical model and ‘matcap’), while others seem more appropriate for deriving and testing new camouflage designs and concepts (e.g. light field method).","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"47 1","pages":"1227008 - 1227008-21"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74979208","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}
F. Bisesto, A. Perna, A. Cosentino, F. Coppola, V. Sacchieri
Coherent beam combining techniques aim to obtain high-power laser beams with good quality and thus enabling several specific applications such as long-range communications, remote power delivering or L-DEW applications. They have received a renewed interest given the very good performances obtainable with high power fiber lasers adopting MOPA architectures and phase locking feedback loops. In the case of fiber lasers, the specific power of a single amplifier is limited by the deleterious effect of SBS. One can enhance the threshold of SBS widening the bandwidth of the field in the amplifier but this contrasts with the need of a spectrally pure field for the adoption of CBC architectures based on phase detection. Arrays with a large number of elements have been demonstrated for narrow-band systems, while wideband phase locking has been reported only in the case of a limited number of elements. The adoption of multi-KW fiber laser amplifiers requires bandwidths of the order 30 GHz. In this paper, we report on the experimental demonstration of a 7-element array coherently combined up to a spectral bandwidth of 47 GHz. The architecture is based on a narrow line single mode master oscillator whose emission is phase modulated to widen the bandwidth. Amplified fields are summed in a tiled aperture geometry and far field PIB is adopted as a metrics for a perturbation hill-climbing algorithm. Phase-locking results and convergence dynamics are analyzed in relation to the bandwidth properties of the oscillator modulation.
{"title":"Large bandwidth lasers coherent beam combining in a 7-element YDFL array using a tailored SPGD algorithm","authors":"F. Bisesto, A. Perna, A. Cosentino, F. Coppola, V. Sacchieri","doi":"10.1117/12.2647871","DOIUrl":"https://doi.org/10.1117/12.2647871","url":null,"abstract":"Coherent beam combining techniques aim to obtain high-power laser beams with good quality and thus enabling several specific applications such as long-range communications, remote power delivering or L-DEW applications. They have received a renewed interest given the very good performances obtainable with high power fiber lasers adopting MOPA architectures and phase locking feedback loops. In the case of fiber lasers, the specific power of a single amplifier is limited by the deleterious effect of SBS. One can enhance the threshold of SBS widening the bandwidth of the field in the amplifier but this contrasts with the need of a spectrally pure field for the adoption of CBC architectures based on phase detection. Arrays with a large number of elements have been demonstrated for narrow-band systems, while wideband phase locking has been reported only in the case of a limited number of elements. The adoption of multi-KW fiber laser amplifiers requires bandwidths of the order 30 GHz. In this paper, we report on the experimental demonstration of a 7-element array coherently combined up to a spectral bandwidth of 47 GHz. The architecture is based on a narrow line single mode master oscillator whose emission is phase modulated to widen the bandwidth. Amplified fields are summed in a tiled aperture geometry and far field PIB is adopted as a metrics for a perturbation hill-climbing algorithm. Phase-locking results and convergence dynamics are analyzed in relation to the bandwidth properties of the oscillator modulation.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"1 1","pages":"122730E - 122730E-10"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73539926","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}
V. Voronin, M. Zhdanova, N. Gapon, A. Alepko, A. Zelensky, E. Semenishchev
The additional sources of information (such as depth sensors, thermal sensors) allow to get more informative features and thus increase the reliability and stability of recognition. In this research, we focus on how to combine the multi-level deep fusion for visible and thermal information. We present the algorithm, combining information from visible cameras and thermal sensors based on the deep learning and parameterized model of logarithmic image processing (PLIP). The proposed neural network based on the principle of an autoencoder. We use an encoder to extract the features of images, and the fused image is obtained by a decoding network. The encoder consists of a convolutional layer and a dense block, which also consists of convolutional layers. Fusing images are in the decoder and the fusion layer operating to the principle of PLIP which close to the human visual system's perception. This fusion approach applied for surveillance application. Experimental results showed the effectiveness of the proposed algorithm.
{"title":"Deep visible and thermal image fusion for enhancement visibility for surveillance application","authors":"V. Voronin, M. Zhdanova, N. Gapon, A. Alepko, A. Zelensky, E. Semenishchev","doi":"10.1117/12.2641857","DOIUrl":"https://doi.org/10.1117/12.2641857","url":null,"abstract":"The additional sources of information (such as depth sensors, thermal sensors) allow to get more informative features and thus increase the reliability and stability of recognition. In this research, we focus on how to combine the multi-level deep fusion for visible and thermal information. We present the algorithm, combining information from visible cameras and thermal sensors based on the deep learning and parameterized model of logarithmic image processing (PLIP). The proposed neural network based on the principle of an autoencoder. We use an encoder to extract the features of images, and the fused image is obtained by a decoding network. The encoder consists of a convolutional layer and a dense block, which also consists of convolutional layers. Fusing images are in the decoder and the fusion layer operating to the principle of PLIP which close to the human visual system's perception. This fusion approach applied for surveillance application. Experimental results showed the effectiveness of the proposed algorithm.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"12 1","pages":"122710P - 122710P-6"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73610803","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}
W. Pan, G. Umana-Membreno, J. Antoszewski, W. Lei, R. Gu, H. Kala, Nima Dehdashtiakhavan, L. Faraone
High performance infrared (IR) sensing and imaging systems require IR optoelectronic detectors that have a high signal-to-noise ratio (SNR) and a fast response time, and that can be readily hybridised to CMOS read-out integrated circuits (ROICs). From a device point of view, this translates to p-n junction photovoltaic detectors based on narrow bandgap semiconductors with a high quantum efficiency (signal) and low dark current (noise). These requirements limit the choice of possible semiconductors to those having an appropriate bandgap that matches the wavelength band of interest combined with a high optical absorption coefficient and a long minority carrier diffusion length, which corresponds to a large mobility-lifetime product for photogenerated minority carriers. Technological constraints and modern clean-room fabrication processes necessitate that IR detector technologies are generally based on thin-film narrow bandgap semiconductors that have been epitaxially grown on lattice-matched wider bandgap IR-transparent substrates. The basic semiconductor material properties have led to InGaAs (in the SWIR up to 1.7 microns), InSb (in the MWIR up to 5 microns), and HgCdTe (in the eSWIR, MWIR and LWIR wavelength bands) being the dominant IR detector technologies for high performance applications. In this paper, the current technological limitations of HgCdTe-based technologies will be discussed with a view towards developing future pathways for the development of next-generation IR imaging arrays having the features of larger imaging array format and smaller pixel pitch, higher pixel yield and operability, higher quantum efficiency (QE), higher operating temperature (HOT), and dramatically lower per-unit cost.
{"title":"Narrow bandgap HgCdTe technology for IR sensing and imaging focal plane arrays","authors":"W. Pan, G. Umana-Membreno, J. Antoszewski, W. Lei, R. Gu, H. Kala, Nima Dehdashtiakhavan, L. Faraone","doi":"10.1117/12.2645270","DOIUrl":"https://doi.org/10.1117/12.2645270","url":null,"abstract":"High performance infrared (IR) sensing and imaging systems require IR optoelectronic detectors that have a high signal-to-noise ratio (SNR) and a fast response time, and that can be readily hybridised to CMOS read-out integrated circuits (ROICs). From a device point of view, this translates to p-n junction photovoltaic detectors based on narrow bandgap semiconductors with a high quantum efficiency (signal) and low dark current (noise). These requirements limit the choice of possible semiconductors to those having an appropriate bandgap that matches the wavelength band of interest combined with a high optical absorption coefficient and a long minority carrier diffusion length, which corresponds to a large mobility-lifetime product for photogenerated minority carriers. Technological constraints and modern clean-room fabrication processes necessitate that IR detector technologies are generally based on thin-film narrow bandgap semiconductors that have been epitaxially grown on lattice-matched wider bandgap IR-transparent substrates. The basic semiconductor material properties have led to InGaAs (in the SWIR up to 1.7 microns), InSb (in the MWIR up to 5 microns), and HgCdTe (in the eSWIR, MWIR and LWIR wavelength bands) being the dominant IR detector technologies for high performance applications. In this paper, the current technological limitations of HgCdTe-based technologies will be discussed with a view towards developing future pathways for the development of next-generation IR imaging arrays having the features of larger imaging array format and smaller pixel pitch, higher pixel yield and operability, higher quantum efficiency (QE), higher operating temperature (HOT), and dramatically lower per-unit cost.","PeriodicalId":52940,"journal":{"name":"Security and Defence Quarterly","volume":"194 1","pages":"1227102 - 1227102-6"},"PeriodicalIF":0.0,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73194536","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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