共查询到15条相似文献,搜索用时 51 毫秒
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文章简要介绍了红外目标旋转模拟器的结构组成、工作原理,给出了红外目标旋转模拟器的目标温度、平均角速度、角速度波动的校准方法,该校准方法能为光电设备的量值溯源提供解决方案. 相似文献
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大面积平行光幕弹着点测试系统 总被引:2,自引:1,他引:1
研究了基于平行激光幕大面积弹着点坐标测试方法.以半导体激光线发生器为光源,用长焦距消球差的柱面菲涅耳透镜形成平行激光幕单元,通过多个平行激光幕单元的无缝拼接可形成大面积靶面.由于平行激光幕单元内沿宽度方向通量密度呈高斯分布,一定直径的弹丸通过光幕的不同横向位置时探测器获取信号不同,因此可根据信号的幅值来细分平行激光幕单元宽度范围内弹着点的位置.通过口径为7.62mm的实弹射击试验验证了细分方法的可行性.结果表明了该系统有足够的灵敏度能获取小目标的过靶信号;在10 m长靶面的试验系统中测量坐标值与弹孔测量坐标值差值的标准差为5.16 mm. 相似文献
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针对红外目标模拟器中分离镜伺服系统的抗干扰控制问题,本文利用变结构控制响应快速,对系统参数变化和外部扰动不灵敏的特点设计了一个滑模变结构控制器.采用指数趋近律与饱和函数相结合的方法对滑模控制器的抖振进行了有效抑制.采用机理分析方法建立了分离镜系统的数学模型.在仿真过程中,利用S函数描述摩擦模型,简化了仿真建模,提高了仿真速度.通过数字仿真并与传统PID控制方法相比较,证明滑模控制器对于分离镜伺服系统的参数摄动和外部干扰具有良好的鲁棒性,可以保证和提高整个红外制导仿真实验系统的仿真精度和实验结果的置信度. 相似文献
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文中以宽带和多目标信号为模型,在虚拟仪器开发环境LabWindows/CVI下,设计和开发了基于PXI总线的水下目标模拟器。目标模拟器产生24阵元平面水声基阵的接收信号,在实验室里模拟海洋环境下的目标回波、混响和环境噪声,提供测试水声设备所需的各种目标信号。最后给出了该系统在水声自导系统调试和性能测试应用中的结果。 相似文献
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In this letter we report a novel technique to measure small laser beam spot sizes. We use the open aperture z-scan technique as a tool to measure the laser beam spot size. This technique measures small spot sizes with accuracy better than 10%. 相似文献
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Izdebski M Kucharczyk W Raab RE 《Journal of the Optical Society of America. A, Optics, image science, and vision》2001,18(6):1393-1398
Certain optical properties can be described in terms of two linear birefringences existing in separate Jones platelets of a medium. One of these, known as Jones birefringence, although occurring naturally in some crystals is too small to be measurable. However, the two birefringences can be induced by an electric field in 4 and 6 crystals for propagation along the optic axis. For an even slightly divergent light beam, natural birefringence may affect accuracy of measurement. Calculations show that in an experiment with a static field the error depends critically on beam divergence, whereas with a modulated field this is not so. 相似文献
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Infrared absorption bands due to water vapor in the mid-infrared regions often obscure important spectral features of the sample. Here, we provide a novel method to collect a qualified infrared spectrum without any water vapor interference. The scanning procedure for a single-beam spectrum of the sample is divided into two stages under an atmosphere with fluctuating humidity. In the first stage, the sample spectrum is measured with approximately the same number of scans as the background. If the absorbance of water vapor in the spectrum is positive (or negative) at the end of the first stage, then the relative humidity in the sample compartment of the spectrometer is changed by a dry (or wet) air blow at the start of the second stage while the measurement of the sample spectrum continues. After the relative humidity changes to a lower (or higher) level than that of the previously collected background spectrum, water vapor peaks will become smaller and smaller with the increase in scanning number during the second stage. When the interfering water lines disappear from the spectrum, the acquisition of a sample spectrum is terminated. In this way, water vapor interference can finally be removed completely. 相似文献
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This study was conducted to generalize from models of human performance in single target search to multiple target search. The specific issue was exhaustive search for the complete set of targets on a search field, extending the work of Chan and Chan from a two-target exhaustive search. Mathematical modelling was based on earlier derivations of search for the first of a set of targets. Model and simulation results showed three quite different relationships between mean search time and the number of targets remaining in a search field. The human search strategy for multiple targets was close to the systematic strategy for the first few targets and was close to the random strategy for the last few targets. Plotting mean search time for multiple targets against the number of targets remaining would be a useful and unique way to show human use of systematic search strategy. 相似文献
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Infrared Fourier transform photothermal beam deflection spectroscopy (PBDS) is briefly outlined. It involves heating a surface by the photothermal effect, using infrared (IR) radiation from a scanning interferometer; energy is transferred to the gas above the surface and the resulting refractive index gradient in the gas is detected by observing the deflection of a laser beam grazing the solid's surface; the deflection is related to the IR radiation which is absorbed, so that the Fourier transform of the deflection signal results in the IR spectrum. PBDS is especially useful for materials which scatter and/or absorb IR radiation so extensively that conventional transmission/absorption techniques are not possible. A variety of examples of applications are given, including spectra of polymers, floor tile, polyester thread and fabric, leather, cellulose, paper, lichen and bone. 相似文献
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In two different laboratories, measurements are performed of the thermal expansion coefficient of several mortar specimens,
based on the thermoelastic effect. The temperature of the sample surface is recorded while the specimens undergo a uniaxial
adiabatic compression. The percentage change of temperature is proportional to the longitudinal strain, the constant of proportionality
being the longitudinal Grüneisen parameter. Through the equation of state, this parameter allows access to the thermal expansion
coefficient once the Young modulus and the specific heat at constant volume are independently available. Results obtained
for groups of equally prepared specimens, using two slightly different experemental setups, are found to be identical within
the experimental errors. These results based on the thermoelastic method, are also consistent with those independently obtained
by direct extensometric methods.
Résumé On présente une méthode de mesure du coefficient de dilatation thermique des matériaux à base de ciment. La méthode est fondée sur l'équation d'état et se base sur la mesure du coefficient de couplage thermoélastique, le paramètre de Grüneisen. Quand un échantillon est soumis à une charge compressive uniaxiale, en régime élastique et en conditions adiabatiques, sa température augmente par l'effet thermoélastique. La variation relative de température est proportionnelle à la déformation longitudinale, la constante de proportionnalité étant le paramètre de Grüneisen longitudinal. L'équation d'état permet d'obtenir le coefficient de dilatation thermique comme le produit du paramètre de Grüneisen longitudinal, de l'inverse du modulus de Young, et de la capacité thermique par unité de volume, à volume constant. On présente une série de mesures comparées, effectuées dans deux laboratoires sur deux séries d'échantillons de mortier. Les échantillons sont soumis à un essai de compression, pendant lequel on enregistre la charge appliquée et la température de la surface des échantillons mêmes. Le paramètre de Grüneisen longitudinal et le modulus de Young sont déterminés par les caractéristiques température-déformtion et charge-déformation. La capacité thermique par unité de volume est déterminée, dans un essai indépendant, comme le rapport de la diffusivité thermique et de la conductivité thermique, qui font souvent partie d'une qualification adéquate du matériau. Le coefficient de dilatation thermique est enfin déduit comme indiqué auparavant. Les valeurs expérimentales obtenues dans les deux laboratoires diffèrent par moins d'une déviation standard. Les valeurs dites sont comparées avec celles obtenues par une méthode extensométrique, indépendante et plus directe. Les résultats des deux méthodes se révèlent concordants. On conclut que la méthode proposée, basée sur l'effet thermoélastique, bien qu'indirecte, conduit à une mesure fine et précise du coefficient de dilatation thermique.相似文献