共查询到19条相似文献,搜索用时 79 毫秒
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本文通过推导高斯光束照明的毛玻璃产生的散斑的互相关函数,得出此光源的曲率中心经光学系统的成像面为激光动态散斑的纯沸腾面。由此给出确定高斯光束曲率中心位置的方法。 相似文献
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动态激光散斑用于透镜轴向象差的测量 总被引:1,自引:0,他引:1
在高斯光束照明下,根据在平面内匀速运动的散射体经光学系统在观察面内产生的动态散斑的复振幅和强度起伏的空-时互相关函数,给出了散斑纯沸腾状态的位置,这位置恰好是点光源经过透镜的成象位置,由此提出了一种测量透镜球差、象散和场曲的新方法,并与其它方法作了比较。 相似文献
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许多文献阐述了白光散斑技术的理论和实验,但是散射体本身的性质缺少定量的描述,白光是复色光这一物理特性没有得到足够的重视.本文把散斑看成一系列随机空间频谱的迭加,建立了数学模型.并从单色非相于光散斑入手,把得出的结论再推广到白光散斑.二、非相干单色光散斑成像散斑记录系统见图1(图示为透射式,反射式的讨论相同).用非相干单色光照明散射体,与文献 相似文献
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本文提出了散射体的散斑模型,考虑了散斑现象的统计特性,讨论了相干光散斑的成象过程,得出了散斑图的公式。公式表明散斑图的空间频率成分和成象系统的传递函数及散射体的频率分布有关,并得到了实验的证实。进而导出了散班衍射晕强度分布公式,解释了晕的散斑结构。 相似文献
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在高斯光束照期下,根据在平面匀速运动的散射体经光学系统在观察面内产生的动态散斑的复振幅和强度起伏的空-时互相关函数,给出了散斑纯沸腾状态的位置,这位置恰好是点光源经过透镜的成象位置;由此提出了一种测量透镜球差、象散和场曲的新方法,并与其它方法作了比较。 相似文献
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激光的强相干性造成了激光投影显示中出现大量干涉条纹和散斑,为了消除干涉条纹和散斑对图像质量的影响,采用旋转新型散射体(Engineered DiffuserTM)的方法在一定积分时间内获得叠加的清晰图像。首先,介绍了激光投影显示中散斑的成因及采用时间平均抑制散斑的理论依据。接着,分析了传统散射体毛玻璃和Engineered DiffuserTM在结构及功能上的区别。最后,建立了旋转新型散射体抑制散斑的激光投影显示实验装置,对比验证了旋转新型散射体抑制散斑的效果。实验结果表明:散斑对比度降低到3.08%,图像质量良好,无明显干涉条纹。该方法满足商用激光投影显示体积小、简单易行等要求。 相似文献
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Christopher Middlebrook Michael Roggemann Glenn Boreman Nikola Subotic Kyle Cooper William Buller Weidong Yang Javier Alda 《Journal of Infrared, Millimeter and Terahertz Waves》2008,29(2):179-187
The first direct measurement of the mutual coherence function of a spatially incoherent infrared beam was performed at 10.6 μm using a pair of infrared dipole nano-wire antennas that were connected to a common bolometer in the center of the pair by short lengths of coplanar strip transmission line. A spatially incoherent source was constructed by dithering a BaF2 diffuser near the focus of a CO2 laser beam. The distance from the diffuser to the nano-wire antenna pair was held constant while the distance from the focus of the laser beam to the diffuser was varied to control the effective diameter of the source. The measured bolometer signal was proportional to the magnitude of the mutual coherence function at the plane of the antennas. The experimental results were found to match the predicted performance closely. If this technology can be extended to large arrays, a form of synthetic aperture optical imaging based on the Van Cittert-Zernike theorem is possible, similar to that performed at microwave frequencies now by astronomers. This has the potential to greatly increase the angular resolution attainable with optical instruments. 相似文献
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星载太阳定标漫反板的漫反射朗伯特性及其辐照衰减特性直接决定了空间遥感仪器在轨辐射定标长期的精度和稳定性。为保证紫外高光谱探测仪的在轨辐射定标精度,在介绍目前常用太阳定标漫反板材料的基础上,提出了一种新型的紫外波段漫反板备选材料:高纯度不透明熔融石英材料HOD,并比对测试了该新型HOD漫反板与传统铝制漫反板的漫反射朗伯特性和辐照衰减特性。结果表明,32个等效太阳时(32ESH)的真空紫外辐照后,HOD漫反板在290 nm衰减为7.5%,优于传统铝制漫反板的10%。并且铝制漫反板在290 nm附近的朗伯特性最大余弦偏差约为40%,而HOD漫反板约为10%。因此,新型HOD漫反板在紫外波段的漫反射特性优于传统的铝制漫反板,可提高空间紫外遥感仪器的在轨辐射定标的长期精度。 相似文献
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本文提出一种指纹图象的特征提取方法,指纹中心点定义在纹线上曲率最大处,从而统一了中心点的定义,提取的细节特征量是特征点的性质、特征点到指纹中心点连线与指纹方向间夹角以及特征点与中心点间隔的纹线数,并进行了对比实验,效果良好。 相似文献
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The quarter-wavelength monopole over an array of radial ground rods is analyzed using the method of moments to obtain the radiated field amplitude and phase characteristics. The phase center is calculated as a function of polar observation angle by finding the apparent center of curvature of the phase contour. It is found that the resulting phase center location is not confined to the monopole axis as has previously been suggested. 相似文献
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Sung-Il Chang Jun-Bo Yoon 《Photonics Technology Letters, IEEE》2006,18(7):814-816
A three-dimensional (3-D) planar microlens with curved sidewalls was fabricated by using the recently developed 3-D diffuser lithography and the polydimethylsiloxane (PDMS) replication method. The sidewall of the fabricated 3-D planar microlens had a radius of curvature of 140 /spl mu/m, and a well-defined focal spot with a width of 1.5 /spl mu/m and a height of 3 /spl mu/m was observed. An excellent single-mode fiber-to-fiber coupling efficiency of 71% was demonstrated by applying the developed 3-D planar microlens, which displayed more than two times the coupling ability compared to that of a conventional two-dimensional planar microlens with straight sidewalls. Finally, it was verified that the coupling efficiency was little affected by variation in the process conditions used for the photoresist mold fabrication. 相似文献
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激光阵列光源角度多样性抑制散斑方法 总被引:3,自引:1,他引:2
搭建测试系统,对宽面源单管半导体激光器(LD)和其组成的二维阵列光源的远场散斑特性进行了测量。使用方形光阑对激光二极管发出的照明光斑进行选择,测试不同位置的光斑的散斑对比度,实验结果表明随着光阑的移动,不同位置处光斑的散斑对比度没有明显的变化趋势,光斑的散斑对比度与光斑的选择区域无关。实验中使用4颗LD组成二维阵列光源引入非相干光源和角度多样性,调节LD与屏幕之间的距离改变相邻LD入射至屏幕的光的夹角,固定CCD物镜相对屏幕的张角,实验结果表明只有当入射光夹角大于物镜相对屏幕张角时,测试的散斑对比度会降低一个1/M1/2因子。 相似文献