Optics/Photonics in Security and Defence最新文献

{"title":"Terahertz time-domain spectroscopy for distinguishing different kinds of gunpowder","authors":"T. Gavenda, V. Kresálek","doi":"10.1117/12.2034126","DOIUrl":"https://doi.org/10.1117/12.2034126","url":null,"abstract":"This article contains information about using terahertz time-domain spectroscopy for the security industry, particularly for distinguishing chosen different kinds of gunpowder. The original focus of described research was the observation of characteristic spectrum of gunpowder (spectral fingerprint) in the terahertz range of the electromagnetic spectrum to use the terahertz radiation for gunpowder detection and identification. The results of this research lead to the finding that researched samples of gunpowder do not have any characteristic spectral lines or peaks in the terahertz range of the electromagnetic spectrum up to 2 THz. However, the comparison of samples of different kinds of gunpowder proves the possibility of their distinguishing by their absorbance (absorption spectrum). Introduction information about motivation of authors, methods of measurement, samples preparation, results of measurements with their interpretation and discussion about the results with conclusion are the main parts of this article.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126493676","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":"THz devices evaluation in a time domain spectroscopy system at 1.55 μm pulse excitation","authors":"I. Kostakis, A. Zandieh, D. Hailu, D. Saeedkia, M. Missous","doi":"10.1117/12.2029218","DOIUrl":"https://doi.org/10.1117/12.2029218","url":null,"abstract":"Following the development of efficient THz devices operating at 1550 nm based on low temperature (LT) grown semiconductor compounds, the effect of the substrate of such devices in the generated THz radiation is investigated, a new compact, portable and reconfigurable fiber based THz spectrometer is built and a pair of THz devices are evaluated in the spectrometer. The key findings are firstly the transparency of the InP substrate to THz radiation, which implies that the generated THz signal from these devices is not affected by the substrate, and secondly the development of a THz spectrometer at 1550 nm laser excitation, which can be used for high quality measurements for various material sensing and characterization applications.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122400233","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":"The evaluation of THz-VIS fused images","authors":"M. Kowalski, N. Pałka, M. Szustakowski","doi":"10.1117/12.2028249","DOIUrl":"https://doi.org/10.1117/12.2028249","url":null,"abstract":"A growing interest in terahertz technology finds support in a large number of applications. One of the most interesting applications of terahertz waves is imaging. The terahertz range of electromagnetic radiation has large potential in the field of hidden objects detection because it is not harmful to humans [1, 2]. However, the main difficulty in the THz imaging systems is low image quality due to low sensitivity and a small number of pixels in detecting modules of cameras Considering the fact that even THz images with low pixel resolution still provide valuable information, it is justified to combine them with the high-resolution images from a visible camera. Image fusion can be used in a wide range of security applications for example detection and identification of hidden objects. Our goal is to build a system harmless to humans for screening and detection of hidden objects using a THz camera. A very important aspect of applying various processing techniques to images is proper assessment of image quality. We propose a combination of two image quality assessment methods (IQA) as a methodology of assessing quality of the fused images and a method to compare image fusion algorithms.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"8900 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128722060","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":"Impulse radar imaging system for concealed object detection","authors":"F. Podd, M. David, G. Iqbal, F. Hussain, D. Morris, E. Osakue, Y. Yeow, S. Zahir, D. Armitage, A. Peyton","doi":"10.1117/12.2029462","DOIUrl":"https://doi.org/10.1117/12.2029462","url":null,"abstract":"Electromagnetic systems for imaging concealed objects at checkpoints typically employ radiation at millimetre and terahertz frequencies. These systems have been shown to be effective and provide a sufficiently high resolution image. However there are difficulties and current electromagnetic systems have limitations particularly in accurately differentiating between threat and innocuous objects based on shape, surface emissivity or reflectivity, which are indicative parameters. In addition, water has a high absorption coefficient at millimetre wavelength and terahertz frequencies, which makes it more difficult for these frequencies to image through thick damp clothing. This paper considers the potential of using ultra wideband (UWB) in the low gigahertz range. The application of this frequency band to security screening appears to be a relatively new field. The business case for implementing the UWB system has been made financially viable by the recent availability of low-cost integrated circuits operating at these frequencies. Although designed for the communication sector, these devices can perform the required UWB radar measurements as well. This paper reports the implementation of a 2 to 5 GHz bandwidth linear array scanner. The paper describes the design and fabrication of transmitter and receiver antenna arrays whose individual elements are a type of antipodal Vivaldi antenna. The antenna’s frequency and angular response were simulated in CST Microwave Studio and compared with laboratory measurements. The data pre-processing methods of background subtraction and deconvolution are implemented to improve the image quality. The background subtraction method uses a reference dataset to remove antenna crosstalk and room reflections from the dataset. The deconvolution method uses a Wiener filter to “sharpen” the returned echoes which improves the resolution of the reconstructed image. The filter uses an impulse response reference dataset and a signal-to-noise parameter to determine how the frequencies contained in the echo dataset are normalised. The chosen image reconstruction algorithm is based on the back-projection method. The algorithm was implemented in MATLAB and uses a pre-calculated sensitivity matrix to increase the computation speed. The results include both 2D and 3D image datasets. The 3D datasets were obtained by scanning the dual sixteen element linear antenna array over the test object. The system has been tested on both humans and mannequin test objects. The front surface of an object placed on the human/mannequin torso is clearly visible, but its presence is also seen from a tell-tale imaging characteristic. This characteristic is caused by a reduction in the wave velocity as the electromagnetic radiation passes through the object, and manifests as an indentation in the reconstructed image that is readily identifiable. The prototype system has been shown to easily detect a 12 mm x 30 mm x70 mm plastic object concealed under cloth","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114514989","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 W-band passive imaging system implemented with rotating diffraction antenna technology","authors":"S. Shylo, Yuriy Sydorenko, D. Wheeler, Douglas Dundonald","doi":"10.1117/12.2028838","DOIUrl":"https://doi.org/10.1117/12.2028838","url":null,"abstract":"The operational concept and results of tests are presented for a prototype W-band passive imaging system based on a planar diffraction antenna. A multi-beam (64 beams) rotating antenna pattern is formed due to the dispersive properties of the antenna and by rotating the antenna around the viewing axis by means of a low power electromechanical drive. The operational frequency bandwidth of 16 GHz is split into 64 sub-bands, one for each ‘beam’. Image formation at short distances, ~ several meters, is possible with the addition of a static lens in front of the rotating antenna unit; far field imaging is also possible without an additional lens. Technical parameters and imaging results from the prototype unit are discussed.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"107 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133739003","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":"Detection of the THz waves from the 5m distance","authors":"M. Walczakowski, N. Pałka, M. Szustakowski, A. Czerwiński, M. Sypek","doi":"10.1117/12.2028852","DOIUrl":"https://doi.org/10.1117/12.2028852","url":null,"abstract":"We report on technical aspects connected with detection of the terahertz (THz) waves reflected from a small target which is situated at the distance of 5 meters. Details of experimental setup are presented. An optical parametric oscillator (OPO) was used as a THz nanosecond pulses radiation source and a hot-electron bolometer (HEB) was applied for pulse detection. A method of spectrum calculation from experimental data is described. Measured reflectance spectra of few materials are presented with explanation of the origin of water vapor hole burning in the reflectance spectrum.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"53 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132772847","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 calibration concept for passive MW imaging using beam steering by frequency shift and aperture synthesis","authors":"E. Schreiber, M. Peichl, M. Jirousek","doi":"10.1117/12.2028641","DOIUrl":"https://doi.org/10.1117/12.2028641","url":null,"abstract":"Passive microwave (MW) remote sensing is used in Earth observation missions for example to estimate the salinity of oceans or the soil moisture of landscapes. In these cases the absolute brightness temperature numbers are important for sufficient accuracy of the estimated geo-physical parameters. Consequently a suitable system calibration network is required. At DLR a radiometric demonstrator for fully-electronic MW imaging was set up at Ka-band, which is based on a combination of beam steering by frequency shift using a broadband slotted-waveguide antenna for one scanning direction, and the application of aperture synthesis for the other direction. Aperture synthesis is well known from radio astronomy, but it is still a new imaging principle for Earth observation or security applications. Hence as well new calibration techniques have to be developed for this kind of scanning mechanism. In this paper a novel approach for a noise-source based calibration method taking into account the antenna losses will be introduced. When using aperture synthesis techniques to determine the absolute brightness temperature values, it is very important, among other things, to know the exact phase transfer function of the system in order to achieve the desired radiometric resolution. Consequently our approach enables phase calibration as well. The paper outlines a proof of concept for this calibration method using a two-element interferometer called VESAS (Voll Elektronischer Scanner mit AperturSynthese) as a demonstrator. The functionality of the demonstrator and the proof of concept of the imaging principle mentioned before are written in detail in [1].","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127489266","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":"Expanded opportunities of THz passive camera for the detection of concealed objects","authors":"V. Trofimov, V. Trofimov, I. E. Kuchik","doi":"10.1117/12.2029046","DOIUrl":"https://doi.org/10.1117/12.2029046","url":null,"abstract":"Among the security problems, the detection of object implanted into either the human body or animal body is the urgent problem. At the present time the main tool for the detection of such object is X-raying only. However, X-ray is the ionized radiation and therefore can not be used often. Other way for the problem solving is passive THz imaging using. In our opinion, using of the passive THz camera may help to detect the object implanted into the human body under certain conditions. The physical reason of such possibility arises from temperature trace on the human skin as a result of the difference in temperature between object and parts of human body. Modern passive THz cameras have not enough resolution in temperature to see this difference. That is why, we use computer processing to enhance the passive THz camera resolution for this application. After computer processing of images captured by passive THz camera TS4, developed by ThruVision Systems Ltd., we may see the pronounced temperature trace on the human body skin from the water, which is drunk by person, or other food eaten by person. Nevertheless, there are many difficulties on the way of full soution of this problem. We illustrate also an improvement of quality of the image captured by comercially available passive THz cameras using computer processing. In some cases, one can fully supress a noise on the image without loss of its quality. Using computer processing of the THz image of objects concealed on the human body, one may improve it many times. Consequently, the instrumental resolution of such device may be increased without any additional engineering efforts.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126796872","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":"T-SENSE a millimeter wave scanner for letters","authors":"D. Nüßler, S. Heinen, T. Sprenger, D. Hübsch, Tobais Würschmidt","doi":"10.1117/12.2029172","DOIUrl":"https://doi.org/10.1117/12.2029172","url":null,"abstract":"Letter bombs are an increasing problem for public authorities, companies and public persons. Nowadays every big company uses in his headquarters inspection system to check the incoming correspondence. Generally x-ray systems are used to inspect complete baskets or bags of letters. This concept which works very fine in big company with a large postal center is not usable for small companies or private persons. For an office environment with a small number of letters x-ray systems are too expensive and oversized. X-ray systems visualize the wires and electric circuits inside the envelope. If a letter contains no metallic components but hazard materials or drugs, the dangerous content is invisible for the most low-cost x-ray systems. Millimeter wave imagining systems offer the potential to close this gap.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132804043","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":"Multispectral THz-VIS passive imaging system for hidden threats visualization","authors":"M. Kowalski, N. Pałka, M. Szustakowski","doi":"10.1117/12.2028338","DOIUrl":"https://doi.org/10.1117/12.2028338","url":null,"abstract":"Terahertz imaging, is the latest entry into the crowded field of imaging technologies. Many applications are emerging for the relatively new technology. THz radiation penetrates deep into nonpolar and nonmetallic materials such as paper, plastic, clothes, wood, and ceramics that are usually opaque at optical wavelengths. The T-rays have large potential in the field of hidden objects detection because it is not harmful to humans. The main difficulty in the THz imaging systems is low image quality thus it is justified to combine THz images with the high-resolution images from a visible camera. An imaging system is usually composed of various subsystems. Many of the imaging systems use imaging devices working in various spectral ranges. Our goal is to build a system harmless to humans for screening and detection of hidden objects using a THz and VIS cameras.","PeriodicalId":344928,"journal":{"name":"Optics/Photonics in Security and Defence","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126586926","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}