An accuracy problem of strain measurement at compression split Hopkinson compression bar experiments with a splitting-beam laser extensometer was considered. The splitting-beam laser extensometer technique was developed by Nie et al. to measure strain of a specimen during its tension under a high strain rate loading condition. This novel concept was an inspiration for the authors to develop own laser extensometer system, which allows for simultaneous and independent measurement of displacement of bar ends between which a compressed material specimen is placed. In order to assess a metrological property of this measuring system, a wide range of high strain rate experiments were performed, including tests with various sample materials (Al 5251, Cu OFE) with different rate of strain, and with the use of two bars material. A high accuracy of the developed laser extensometer was found in measurement of specimen strain, for which uncertainty is not greater than 0.1% and, for a typical specimen dimension, the maximum permissible error is 4.5 μm.
W artykule zaprezentowano konstrukcję laserowego miernika prędkości opracowaną w Instytucie Optoelektroniki Wojskowej Akademii Technicznej we współpracy ze spółką ZURAD z siedzibą w Ostrowi Mazowieckiej, w ramach projektu PBS1/B3/10/2012 „Ręczny fotoradar laserowy” finansowanego ze środków Narodowego Centrum Badań i Rozwoju. Przedstawiono zasadę działania, funkcjonalność oraz parametry zaprojektowanego miernika.
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This article presents construction of laser speed meter (laser speed gun) designed and built in Institute of Optoelectronics of Military University of Technology in collaboration with the company ZURAD settled in Ostrów Mazowiecka. Work is a result of project PBS1/B3/10/2012 “Handheld lidar with camera” financed from the National Center for Research and Development. Basic principles of work, functionality and achieved parameters of designed speed gun are also shown.
Artykuł przedstawia istotne kwestie związane z opracowaniem sytemu laserowej transmisji danych. Omawia zasadę transmisji danych zarówno w kierunku od nadajnika laserowego, gdzie zastosowano modulację położenia impulsu, jak i w kierunku do nadajnika, gdzie następuje modulacja promieniowania odbitego. Wyniki przedstawionych w artykule badań terenowych potwierdzają możliwość zastosowania opracowanej metody, w obszarze cywilnym, do monitoringu i telemetrii urządzeń nieposiadających źródeł promieniowania. W zastosowaniach militarnych system może służyć do identyfikacji obiektów własnych na polu walki z wykorzystaniem impulsowego dalmierza laserowego w roli intrerogatora.
EN
The article presents the main aspects related to the development of nonconventional asymmetric laser data transmission system. It describes the principle of data transmission in both the direction away from the laser transmitter, wherein a pulse position modulation is used, and in the opposite direction, where the modulation of the reflected radiation is performed. The results presented in the article confirm the possibility of using the described technology in the civilian area for monitoring and telemetry, where devices without radiation sources are taken into account. In military applications, the system can be used to identify own objects and forces on the battlefield by the application of pulsed laser rangefinders which are currently a standard battle equipment.
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A variety of optoelectronic devices (rangefinders, velocity meters, terrestrial scanners, lidars, free space optics communication systems and others) based on semiconductor laser technology feature low-quality and highly asymmetric beams. It results from optical characteristics of the applied high-peak-power pulsed laser sources, which in most cases are composed of several laser chips, each containing one or a few active lasers. Such sources cannot be considered as coherent, so the resultant beam is formed by the superposition of many optically uncorrelated sub-sources. Far-field distribution of laser spots in such devices corresponds to the shape of laser emitting area, which instead of desired symmetry shows layout composed of one or several discrete lines or rectangles. In some applications, especially if small targets are concerned, it may be crucial to provide more symmetrical and uniform laser beam cross-section. In the paper, the novel strategy of such correction, combining coherent and incoherent approaches, is presented. All aspects of technological implementations are discussed covering general theoretical treatment of the problem, diffractive optical element (DOE) design in the form of computer generated hologram (CGH), its fabrication and testing in case of selected laser module beam correction.
We report methodology of three-dimensional laser beam shaping. The analytical and numerical analysis is presented. A strategy for designing optical system involves the controlled application of aberrations which is realized by specific aspheric lens shaping. The goal is to obtain the desired optical power density distribution in space, which is optimal for selected application. The proposed method is discussed with regard to the design of optical transmitter for laser shooting simulator, however the developed methodology can be used for a number of other light shaping applications.
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Miniature range finding modules based on pulsed semiconductor laser technology are becoming more and more popular components of a variety of modern optoelectronics devices where precise, fast and eye-safe range estimation is needed. Current trends associated with minimization of both physical dimensions and cost of such modules lead to the design approach relying on exact meeting the requirements of a given application, concerning the spatial resolution and especially the maximum range. Optical components of a rangefinder cover a substantial part of its cost and determine its overall dimensions, but primarily - the indigenous parameters of the transmitter and receiver trains are crucial for the maximum measurable range. The quantitative analysis of transmitter optics aberrational characteristics impact on signal-to-noise ratio range dependence and thus the maximum range of a laser rangefinder is presented in the paper. Modern optical fabrication technology offers a huge range of solutions, changing in imaging/projecting characteristics which implies the price level as well. Rangefinder optics has a very specific task which sometimes makes it unreasonable to fight for the diffraction limited performance. The article provides the approach how to determine the acceptable level of optical aberrations which still does not degrade the measurable range significantly.
An X-ray tube with a needle-like anode (NAXT) built in our Laboratory, its design and basic operating parameters are presented. The process of electron beam forming and influence of external and internal magnetic fields is discussed. The tube properties essential from the point of view of its application in X-ray generators as well as disadvantageous thermal effects caused by flow of heat generated in the tube target to irradiated objects are discussed. The tube is almost a point-like source of X radiation emitted into 4đ geometry; the dose rates are on the order of 1 Gy/min at the distance of 10 mm from the anode cap. Preliminary tests show the tube may be useful in brachytherapy of cancer tumors of diameter up to 30 mm. The tube may also be an interesting device in widely understood field of irradiation techniques.
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