This PDF file contains the front matter associated with SPIE Proceedings Volume 10795, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

High-performance short-wavelength infrared (SWIR) photodetectors can be realized in the InGaAs material system, providing a typical cutoff wavelength of 1.7 μm, which covers a wide part of the nightglow spectrum as well as the emission lines of available laser sources at typical telecom wavelengths around 1.55 μm. However, both, active and passive SWIR detection systems are mostly required to provide high responsivities and very low dark currents in order to detect extremely low photon fluxes. This can be achieved with pin photodiodes with high responsivities and very low dark current characteristics or by utilizing the internal signal gain as provided by avalanche photodiodes (APDs). We develop SWIR photodetectors based on InGaAs/InP pin diodes and InGaAs/InAlAs/InP APDs as single-element detectors as well as focal plane arrays (FPAs). The planar processed InGaAs/InP pin photodiodes for low-light-level SWIR cameras exhibit dark current densities of 10^-7 A/cm² at room temperature for 15 μm pitch detector elements. For the APDs, emphasis is put on the vertical detector design. Within three design iterations, the operating voltage for useful gain values M ~ 10 could be reduced from 27 V down to 18 V, which was crucial for the operation with the voltage limitation of the read-out circuit. FPAs of such InGaAs-APD material have been successfully integrated into SWIR cameras with 640 × 512 pixels at 15 μm pixel pitch. The avalanche operation on camera level has been demonstrated for both kinds, the standard (passive) as well as gated-viewing operation modes.

This paper presents the results of high-performance infrared detectors (IRFPA – InfraRed Focal Plane Array) based on uncooled microbolometers with 17 μm and 12 μm pixel pitch and a chip-scale-package as the vacuum package developed and fabricated by Fraunhofer-IMS. Like CMOS image sensor IRFPAs also have been following the trend of reducing the pixel size in order to reduce the costs and increase the optical resolution. For microbolometer based uncooled IRFPA the pixel pitch has been reduced from 35 μm pixel pitch ten years ago via 25 μm and 17 μm down to 12 μm. Fraunhofer IMS has developed digital IRFPAs featuring a direct conversion of the microbolometer’s resistance into a 16 bit value by the use of massively parallel on-chip Sigma-Delta-ADCs achieving a high scene temperature dynamic range of more than 300 K and a very low NETD-value below 50 mK. Due to a broad-band antireflection coating the digital IRFPAs achieve a high sensitivity in the LWIR (wavelength 8 μm to 14 μm) and MWIR (wavelength 3 μm to 5 μm) range. In this paper the microbolometer, the vacuum-packaging, the architecture of the readout electronics, and the electro-optical performance characterization will be presented.

Infrared imagery has been used in many areas such as military, surveillance, medical imaging and numerous industrial branches. The recent increase in the use of infrared (IR) imaging techniques in various fields draws the attention of more studies towards this area. One of the common problems of the thermal IR detector units is the existence of bad pixels. Bad pixels may arise from various reasons such as manufacturing processes or operating conditions. This phenomenon is commonly dealt with well-known calibration methods. However, they are generally applied at factory level or they interrupt the operational use due to the need for utilizing a uniform reference scene. For those reasons recent methods employ scene based approaches without requiring a special equipment. Those types of methods commonly make some assumptions based on statistical characteristics of bad pixels. They mainly assume that bad pixels deviate at a certain level from their neighboring pixels. They rely on sufficient variation of scene content in time and the fact that possible false detections can be canceled out due to scene variation. Nevertheless, this assumption does not always hold, especially when the camera is stationary. In such cases, some distinctive parts of the underlying scene may be falsely regarded as bad pixels. To that end, we develop a method that is able to isolate the scene content from bad pixels in order to eliminate erroneous detections of scene parts. The proposed method benefits from the motion of the camera which provides responses of different pixels for the same scene region. From this information, we expect similar responses for the registered pixels, if they are not defective. On the other hand, if the pixel responses are exceedingly different, then we can deduce that the corresponding pixel may be defective. For this purpose, we first register adjacent frames using an efficient 1D projection based matching method. To ensure a more robust registration, we use edge maps rather than the intensity image. After the registration of two frames, we construct an error map for the overlapping regions of the two frames. We declare our candidate defective pixels by assessing the deviation levels of error values. Candidate pixels are accumulated across non-stationary frames to obtain temporally consistent detections. Since our inter-frame registration step provides motion information, we avoid accumulation when camera is stationary. We also prevent erroneous registrations by checking for the sufficient scene detail. The performance evaluations are carried out on an extensive dataset consisting of real thermal camera images. The dataset contains a wide variety of scene content and various scenarios featuring stationary camera conditions that causes failures in traditional statistical variation based approaches. The results of our experiments are assessed in terms of true and false bad pixel detections as compared to ground-truth bad pixel labellings. The results show that the proposed inter-frame registration based bad pixel detection method achieves successful results without any assumption about scene content and any additional reference surface.

Many microelectronic devices require bonding dissimilar materials to operate under extreme operating conditions. Furthermore, certain applications, such as cooled infrared (IR) detection, require large temperature cycles between ambient and cryogenic temperatures under ultra-high vacuum (UHV) conditions. The complex expansion and contraction of the various materials within the detector package structure during temperature cycles introduces significant internal stresses that may ultimately result in the failure of the sensor and/or the package. Added to this complexity is the process sensitivity of the fabricated device to elevated temperatures and adhesive application. With orders-ofmagnitude difference between gap sizes, adhesive properties such as viscosity, cure kinetics, and process temperatures become paramount for successful sensor integration. In addition, stringent outgassing requirements associated with ultra-high vacuum application further complicates the selection process for cryogenic adhesives. Under these constraints, a myriad of commercial epoxy adhesives were evaluated. We devised a characterization methodology using a combination of various analytical techniques which elucidated the complex flow properties, and cure kinetics while highlighting critical characteristics necessary for a successful material for this application with a focus on rapid cycles of learning. As the application space matures, we see the need for a next generation of adhesives for demanding and ubiquitous infrared sensing applications.

Detecting maritime targets with electro-optical (EO) sensors is an active area of research. One current trend is to automate target detection through image processing or computer vision. Automation of target detection will decrease the number of people required for lower-level tasks, which frees capacity for higher-level tasks. A second trend is that the targets of interest are changing; more distributed and smaller targets are of increasing interest. Technological trends enable combined detection and identification of targets through machine learning. These trends and new technologies require a new approach in target detection strategies with specific attention to choosing which sensors and platforms to deploy.

In our current research, we propose a ‘maritime detection framework 2.0’, in which multi-platform sensors are combined with detection algorithms. In this paper, we present a comparison of detection algorithms for EO sensors within our developed framework and quantify the performance of this framework on representative data.

Automatic detection can be performed within the proposed framework in three ways: 1) using existing detectors, such as detectors based on movement or local intensities; 2) using a newly developed detector based on saliency on the scene level; and 3) using a state-of-the-art deep learning method. After detection, false alarms are suppressed using consecutive tracking approaches. The performance of these detection methods is compared by evaluating the detection probability versus the false alarm rate for realistic multi-sensor data.

New types of maritime targets require new target detection strategies. Combining new detection strategies with existing tracking technologies shows potential increase in detection performance of the complete framework.

The acquisition of complex data of the recorded scene is an important task for video analysis of the processes occurring. The use of IR images allows obtaining data on additional characteristics that are not visible in the optical range. The data obtained by IR sensors can be in the near and far range, which makes it possible to see objects in the dark or to obtain data on their temperature. In the second case, the boundaries of objects are vague and difficult to correlate with the usual optical ranges. To do this a combination of data obtained by a pair of cameras is used. In this paper, we propose using the algorithm for stitching IR images based on data obtained in the optical range. To this end, an approach will be applied that includes parallel analysis of data on: saliency maps; search for boundaries and key points; reduction of bit resolution of images with preservation of borders; image matching; filtering data and restoring the sharpness of object boundaries. As an example, the result of combining data obtained under poor lighting conditions and the results of combining television images will be presented.

Optical techniques have been widely studied for securing and validating information, which is one of the most important challenges of the present time. In this work, we study simultaneous authentication of multiple input encrypted images which have been multiplexed in a single plane. The interference-based encryption architecture is used to generate two phase masks for each distinct image, which would serve as the phase lock and the phase key. The phases are made sparse by randomly retaining few pixels of the phase values. The phase locks corresponding to different images are then multiplexed in a single plane. For authenticating the phase masks, the concept of nonlinear correlation has been applied, which offer better correlation peaks than the conventional joint transform correlators. The proposed idea aims to achieve simultaneous encryption and authentication of multiple images and overcomes the constraints of storage issue.

Optical information security techniques are developed at a fast pace over the past two decades. In the present scenario, where enormous amount of data is being exchanged, information security plays an important role in protecting the information/data from unauthorized use/access. In this context, securing information using optical means has become relevant, given the suitable features of speed and multiple degrees of freedom that optical cryptosystems offer. Asymmetric cryptosystems have been introduced as an upgrade over the conventional double random phase encoding technique and they show resistance towards the known-plaintext attack. This paper reviews the symmetric and asymmetric cryptosystems and their attack analysis.

Polarimetric sensing provides additional scene information which can be used to enhance the target detection and recognition performance of an imaging system. Such information is particularly valuable in the discrimination of weak target signatures from their surroundings and, as such, is attracting a growing interest for future military and surveillance applications. However, the extraction of polarisation information adds complexity in terms of the physical sensor design and the required data processing. Imaging polarimeters typically require four images to be captured of the same scene in different polarisation orientations through either time or spatial division techniques. These sensor architectures introduce system performance constraints in terms of temporal and spatial resolution as well as the attendant degradations associated with the use of additional optical components. Issues associated with the physical envelope, operational robustness, and cost must also be considered. In terms of the processing of the polarimetric data, accurate registration and calibration is required to extract small polarisation signatures which are typically found in natural scenes. The polarimetric image data must then be processed using an image fusion or data fusion method which introduces further demands on the software design and system processor. For some applications, these limitations are acceptable relative to the polarimetric gain, whilst in others a conventional imaging sensor may offer a better overall solution. Consequently, it is important that a trade-off analysis is undertaken which evaluates the realistic performance gains with respect to the implementation and cost issues.

The performance of thermal electro-optic infrared sensors (EO/IR) may be limited in certain specific circumstances, particularly for the detection and identification of targets embedded in an isothermal scene, i.e. when there is insufficient thermal contrast between the targets against their surrounding background. Such situations generally occur at the beginning and end of the day, but can also happen at any time during the day. One way to cope with this limitation is to employ EO/IR sensors that are sensitive to the polarization states of light. With this intention, Defence Research and Development Canada (DRDC) has developed thermal infrared multispectral and hyperspectral polarimetric imaging systems and spectral algorithms to extract the polarized radiance components of targets of interest, and use this additional information to enhance detection and identification while reducing false alarm rate. This paper presents experimental results from measurements using ground-based multispectral and hyperspectral polarimetric imaging sensors to acquire the polarized radiance of targets set up at multiple orientation angles with respect to the sensors lineof-sight (LOS). The objectives of the experiments were to study the phenomenology of polarized surface radiance in the Long-Wave Infrared (LWIR) and assess the effect of different materials on the resulting s-polarized and p-polarized spectral components. Experimental results show the advantages of thermal multispectral and hyperspectral polarimetric imaging sensors over conventional unpolarized ones to discriminate targets against their background, particularly during thermal cross-over periods.

In this report the development of a low SWAP-C mid-infrared imaging system is outlined. This system is designed with a commercially available Vanadium-oxide (VOx) microbolometer camera costing $250 controlled via a Raspberry Pi (RPi) and Python. The camera used was previously characterized to have a NEDT of 25 mK for an integration time of 3.43s at 7 Hz framerate, but from software modifications discussed in this paper it was found that the cameras framerate can be pushed to 32 Hz lowering this integration time to 0.75 s. Due to the low SWAP-C characteristics of the design and the plug-and-play nature of the camera paired with Python code, this system can enable MIR imaging applications that are currently limited by the SWAPC characteristics of currently available detection systems. After outlining the development of interfacing the camera with a computer/microcontroller, the cameras code is extended to a client-server operation that allows for wireless control of the imaging system. This further enables remote operation for applications such as dronebased monitoring/surveillance or trace explosives detection. The report concludes with the discussion of two potential applications of distributed imaging and spectroscopic organics detection.

A compacted ball pod of image fusion system of middle wave band infrared and visible light image is designed and manufactured and tested. The system is composed of image collecting, processing and displaying part. Image collecting part includes a cooled infrared bolometer and a CCD camera. Image process part is a complex circuit penal composed of TMS320DM642, TVP5150, SAA7121H, SDRAM and other electronic components, while displaying part is computer or LCD. The focus length of cooled infrared bolometer is 300/75mm of Ge lens and that of CCD is continuous 10-300mm to match the field of view of bolometer. The optical axises of them are rectified to be parallel carefully, thus they can aim at the target in infinite distance. The response wavelength of the cooled infrared bolometer is 3.3-4.8μm and that of CCD is 0.2~1.1μm. The pixel of bolometer is 320×256 and that of CCD is 720×576. Images of bolometer and CCD are decoded in the input circuit of TVP5150 and form the digital signal of BT.656, then the decoded videos are transferred to TMS320DM642 circuit. The pixel number of bolometer is increased to 720×576 in the DM642 to match that of CCD camera, the decoded images are stored in SDRAM temporally, then the images of bolometer and CCD are fused under the weighted average algorithm in order to keep the real time response. The output image is encoded to PAL format in SAA7121H, so as to be displayed in monitor. The experiment in room and the experiments outside indicate the advantage of fusion algorithm in some degree. By comparing the observing result of three images of infrared, visible, fusing images, a primary conclusion is obtained that the weight coefficient will influence the fusing effect in different circumstances. Next a modified fusion algorithm of pixel comparing of infrared and visible images will implant to the DM642.

Fraunhofer IOSB (Ettlingen, Germany) developed and built a measurement system to verify laser threat detection. The system has been given the name MARLA (Maritime Lasermessanlage), eng.: maritime laser measurement system. It is an integral part of an exercise and test range for electronic warfare of the German Navy at Wehrtechnische Dienststelle für Schiffe und Marinewaffen, Maritime Technologie und Forschung WTD 71, Eckernförde, Germany.

The system provides realistic simulations of various laser-based threats to ships on sea and allows studies of the efficacy of onboard laser warning receivers. MARLA assists laser counter-measures and enables to include environmental studies (atmospheric transmission, water reflections etc.). Redundant system design ensures laser safety even in public areas.

The core of MARLA is a modular laser unit (LU) consisting of five laser modules (LM) and the dedicated laser controllers (LC). The laser modules are mounted on a pan-tilt positioner. MARLA covers the most common laser threats like laser target designator (LTD), laser range finder (LRF), laser beam rider (LBR) and laser dazzler (LD). The individual laser modules are based on commercially available laser sources fitted with multi-stage attenuators to set the laser irradiance within a range of seven orders of magnitude without losing beam quality. By means of a photo detector, the energy of the emitted laser pulses is recorded. An integrated beam shaper enables to vary the beam divergence.

The further crucial parts of MARLA are the control and data acquisition system with operating and visualization software and a general laser safety monitoring system. All the subsystems are integrated into a climate-controlled movable 20' sea container. Use of a stand-alone verification system provides reference data to verify the actual on-site irradiation at the test target.

Einstein's general relativity puts forward the theory of gravitational wave and black hole, and the research and detection of gravitational waves are of great significance to astrophysics and cosmology. The detection of gravitational radiation from various wave sources has always been a major research topic in the world. Among them, X-ray energy collection and detection technology is one of gravitational wave research and detection methods. In this paper, the manifestation of gravitational wave and the characteristics of black hole formation are discussed, and the mechanism of X-ray imaging is analyzed. A lobster eye type X-ray telescope is designed, and the glass wire array unit with the aperture of the imaging device is studied. Based on this technology, the automatic precision measurement of the size of glass wire is controlled, and the automatic precision measuring system is developed, and the control precision of the glass wire production process is realized.

A high-energy electro-optically Q-switched Nd:YAG laser at 1064 nm is presented, which can provide the largest output pulse energy of 196 mJ with the pulse duration of 12 ns and the repetition rate up to 30 Hz. The crossed-Porro resonator and zigzag slab gain medium are utilized to increase the misalignment tolerance of resonator up to 2 arcmin and minimize the divergence angle of laser beam to 1.7 mrad. We control the initial population inversion by intra-cavity quasi-CW lasing to limit maximum output pulse energy, and the excess pump energy is used to overcome performance degradation dependence on environmental temperature. As a result, a nearly constant output pulse energy can be obtained over a wide operating temperature range.

Based on previous work on thermal imager performance analysis at Fraunhofer IOSB using specific scenes and patterns, we present our advances in setting up a testbed for thermal imager characterization with a MIRAGE™ XL infrared scene projector.

In the first part, we outline the experimental setup of our testbed. It allows for mimicking infrared imaging of real scenes in a controlled laboratory environment. We describe the process of dynamic infrared scene generation as well as the physical limitations of our scene projection setup.

A second part discusses ongoing and future applications. This testbed extends our standard lab measurements for thermal imagers by a image based performance analysis method. Scene based methods are necessary to investigate and assess advanced digital signal processing (ADSP) algorithms which are becoming an integral part of thermal imagers. We use this testbed to look into inferences of unknown proprietary ADSP algorithms by choosing suitable test scenes.

Furthermore, we investigate the influence of dazzling on thermal imagers by coupling infrared laser radiation into the projected scene. The studies allow to evaluate the potential and hazards of infrared dazzling and to describe correlated effects. In a future step, we want to transfer our knowledge of VIS/NIR laser protection into the infrared regime.

Celestial image backgrounds are relevant to many upward-looking sensors, particularly those operating at altitudes where the presence of clouds is minimal, and the absorption of the atmosphere is negligible. In this paper, a method is presented for the generation of synthetic celestial background imagery. For the determination of star and planet signatures, the technique uses third party databases with the underlying assumption that the various spectra follow Planck’s blackbody spectral distribution. An Image Generation Tool (IGT) has been developed to create synthetic celestial imagery within any spectral band and for any imaging sensor. The approach taken within the IGT provides a fast and efficient approach for image generation which makes the technique viable for both single frame and image-sequence generation. Example image data is presented for the MWIR spectral band (3-5μm) and the effects of noise and image blur are examined. It is shown that the cooler, brighter stars can exceed practical noise-levels in the MWIR, leading to potential false-alarm signatures.

Blackbodies are the appropriate tools for IR sensors calibration and test. A well-known property of these objects is their emissivity factor equals 1 while their transmission and reflection factors equal 0. Though some high emissive coatings with emissivity higher than 0.99 are now available on the market, a residual reflectivity factor always remains. The first part of this paper demonstrates the influence of the reflectivity factor on the radiated energy of a blackbody especially for blackbodies radiating at temperatures close to or below the ambient temperature. It happens that the difference between this radiated temperature, or apparent temperature, and the measured temperature may be of several tenths of degrees! Such a difference leads to great uncertainty in the calibration procedure of thermal sensors. The case of sensors tested and calibrated into climatic chambers for outdoor applications is particularly critical. The usual method to compensate this difference is to take emissivity and consequently reflectivity factor into the calculation of the theoretical irradiance received by the sensor. This calculation requires a live knowledge of the ambient temperature. While this may not always be the case, calculating the true irradiance i.e. the apparent temperature radiated by the reference source remains a complex calculation for major users of blackbodies. Indeed, they expect their blackbody source to be reliable and an actual reference source whatever the conditions of use. The second part of this paper presents a reminder about this calibration method of the absolute temperature of IR reference source and the correction method when ambient temperature doesn't change. The third part describes the integrated compensation method of the ambient temperature into the new controller of HGH's blackbody sources making these sources actual IR reference sources whatever the operating conditions.

In this paper, a target and background driven simulation procedure is developed for optimal band analysis and performance evaluation of multispectral sensors for dim target detection, in which the observation geometry, target and background radiant characteristics, and the influence of infrared sensor system are integrated into. With the specified sensor altitude, the BeiHang University - Atmospheric Transfer Model (BHU-ATM) is adopted to calculate spectral irradiances of space-variant sky background. When a target with an assumed altitude exists in one line of sight (LOS), the corresponding nadir angle is used to calculate the distance between the target and the sensor, which impacts the target spectral irradiance at the sensor aperture. To analyze the optimal band for target detection, a set of spectral response functions with different central wavelengths and bandwidths are designed to calculate the target-to-background contrasts as well as the signal-to-noise ratios (SNRs). To demonstrate the usefulness of the developed procedure, typical sensor parameters are used to analyze the optimal band for aircraft detection. The band achieving the highest SNR is selected and used in the radiant image simulation for performance evaluation. The results show that the detection performance is related to spectral band as well as the LOS direction.

Image-based Electro-Optical system simulation including an end-to-end performance test is a powerful tool to characterize a camera system before it has been built. In particular, it can be used in the design phase to make an optimal trade-off between performance on the one hand and SWaPC (Size, Weight, Power and Cost) criteria on the other. During the design process, all components can be simulated in detail, including optics, sensor array properties, chromatic and geometrical lens corrections, signal processing, and compression. Finally, the overall effect on the outcome can be visualized, evaluated and can be optimized. In this study, we developed a detailed model of the CMOS camera system imaging chain (including scene, image processing and display). The model simulation was evaluated by comparing simulated (display) imagery with recorded image using both physical (SNR) and psychophysical measures (acuity and contrast thresholds using the TOD-methodology with a human observer) for a range of conditions: different light levels, moving stimuli with different speeds, movies and single frames. The performance analysis show that the model simulations are largely in line with the recorded sensor images with some minor deviations. The result of the study is a detailed, validated and powerful sensor performance prediction model. This project has received funding from the Electronic Component Systems for European Leadership Joint Undertaking.

A broadband reference source of optical radiation emitting at the same time longwave thermal radiation in the MWIRLWIR band and shortwave light in spectral band from middle UV to the middle SWIR is presented in this paper. Since this reference radiation source works at the same time like a typical low temperature blackbody in the MWIRLWIR range and as a source of white light in the UV- SWIR range it has been called a color blackbody. This reference radiation source cab be a perfect solution for systems for testing multi-sensors imaging systems or fused imagers.

For surveillance and target acquisition systems the shorter wavelength regions, i.e. VIS/NIR and in particular SWIR (short wave infrared) have regained importance due to their unique information content and due to technological developments. There is a multitude of imaging systems in that range (400 nm to 1800 nm) extending from simple driver cameras for daylight operation (illumination levels 10 klux or more) to sophisticated night vision devices operating at illumination levels below 1 mlx. Advanced systems using signal and image processing or even AI will only work properly if some performance criteria are met. The requirements to test such systems are demanding. For these systems a suitable lab testing equipment is required to measure performance in a controlled manner. LESOYS has designed and produced a flexible and yet compact test system, the AMT 10. This system is capable of covering over 8 decades of illumination resp. irradiation levels and a vast range of spatial frequencies of test patterns for the spectral range 400 nm to 1800 nm. The primary tests include the measurement of the Minimum Resolvable Contrast MRC, Modulation Transfer Function MTF, Signal-to-Noise S/N, and other figure of merits. The contrast can be adjusted continuously in the range from 100% to 0.1% with one single target. By the use of conversion filters, the setup can easily be adapted to different colour temperatures. The operation is PC controlled and occurs in a semi-automatic manner. The test station is calibrated not only in photometric and radiometric units, but also in the new SWIR radiance measure of Swux/sr.

The accurate and non-destructive estimation of the properties of coatings on metals via infrared spectroscopy is investigated in the present paper in order to inspect the traceability of the metals. First of all, the class of homogeneous coatings such as varnishes is examined, focusing on the extraction of the electrical properties and thickness through simple spectroscopic measurements. The thickness extraction originates from the multiple interferences that occur when an incident electromagnetic wave is reflected from a finite thickness layer via a procedure known as InfraRed Interference Method. The theoretical analysis is realized via the combination of fundamental electromagnetic and transmission line theories, while several measurements at the infrared region are conducted on varnishes with different electrical properties and thicknesses atop metals, in order to facilitate the accuracy of the proposed method. Moreover, the analysis is extended towards inhomogeneous materials such as highly absorbable pigments that are utilized to decrease efficiently the radar cross section of aircrafts. The Kubelka-Munk theory is utilized to estimate the scattering and absorbing properties of such materials. Additionally, various measurements and simulations are conducted on samples of different thicknesses to determine the penetration depth of infrared light and estimate the absorbing efficiency.

Single-pixel imaging was initially based on a statistical model, which uses a series of random patterns for illumination. This means that it requires a great number of measurements (much larger than pixel counts) and long data-acquisition time. Therefore it is necessary to enhance the effective of information collection and reconstruction by employing some priori information. In this paper, a single pixel imaging system is proposed based on APD and Spatial light modulator. And then an image reconstruction algorithm is proposed based on non-local means (NLM). Based on that there are a large number of similar patches within an infrared image, NLM method can abstract the non-local similarity information and then the value of image pixel can be estimated. The reconstructed image is obtained by minimizing a cost function.

Infrared spectral imaging has been used in many fields, such as gas identification, environmental monitoring and target detection. In practical application, it is difficult to classify the spectrum between target and background due to cluster background and instrument noise. This article introduces the design of a modular FTIR imaging spectrometer based on interference optics and accurate control module. Based on this instrument, a spectral feature analysis and gas identification method is proposed and verified via experiment. The exact steps and algorithms include radiometric calibration, spectral pre-process, and spectral matching. First, multiple-points linear radiometric calibration is indicated to improve the calibration accuracy. Secondly, the spectral pre-processing methods are realized to decrease the noise and enhance the spectral difference between target and background. Thirdly, spectral matching based on similarity calculation is introduced to realize gas identification. Three methods, Euclidean distance (ED), spectral angle mapping (SAM) and spectral information divergence (SID), are derived. Finally, an experimental test is designed to verify the method proposed in this article, where SF6 is taken as the target. According to the results, various algorithms have different performance in time consumption and accuracy, and the proposed method is verified to be reliable and accurate in practical field test.

A fiber optic distributed system based on Brillouin scattering (BOTDR) is an interesting alternative for the load monitoring of building structures and line structures. For the purpose of monitoring deformations, special fiber optic cables with a close bond between optical fibers and cable protective elements are specified. It turns out that standard telecommunication optical cables can be used for some applications in the civil engineering. This paper provides an analysis of the impact of using these cables in harsh environments that is an integral part of engineering structures. The primary interest of this paper is the study of the influence of excessive humidity and temperature variation on the life and optical properties of standard cables implemented in building structures for measurement applications. The results are derived from long-term testing of standard fiber optic cables implemented in concrete structures in harsh environments to determine the suitability of using these cables for the reliability of long-term monitoring of building structures such as buildings, bridges or tunnels.

The undesirable dynamic effects of harmonic vibrations due to various devices and technologies are commonly monitored using by seismic stations operating on the principle of mechanical vibration systems (using on horizontal foundation structures or rock mass) or by resistance strain gauges (using e.g. on vertical concrete or steel elements). Modern, progressively evolving alternative to monitor these dynamic effects are methods based on fiber-optic principle. There is used fiber Bragg grating (FBG) or fiber-optic interferometric sensors. At the experimental level the article presents results comparison of conventional approaches to the monitoring of harmonic vibrations and approaches based on fiber-optic principle. Data was process in both amplitude and frequency domain.

Road car transport is today the main species of cargo and passenger transport. However, car transport is accompanied by large negative effects with adverse environmental impacts. Therefore, it is an effort to shift part of the transported costs to rail transport. But the problem is vibrations which created the passing vehicles. The vibrations are transmitted over the rails and the railway infrastructure into the rock environment. These vibrations can adversely affect buildings around the railroad. This article presents a comparison of vibration measurements using a classical commonly used seismic sensor and innovative fiber-optic interferometric sensor. Presented results are based on the real measurements of train traffic. Presented results can serve as a basis for mathematical models which predict the future load of objects in the vicinity of railway tracks.