共查询到18条相似文献,搜索用时 156 毫秒
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用全息透镜组成傅里叶变换系统 总被引:3,自引:0,他引:3
本文将全息透镜作为一般的傅里叶变换元件,组成傅里叶交换系统,进行了相关运算以及模糊图象处理等实验.结果表明,对全息透镜傅里叶变换系统进行某些光学信息处理工作是可行的. 相似文献
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分数傅里叶变换光学实现的基本单元 总被引:12,自引:0,他引:12
提出一些实现分数傅里叶变换的新型的基本光学单元。这些基本单元仅使用一个透镜和一个菲涅耳衍射,给光学设计增加一些新的可选基本类型,对于给定焦距的透镜,它能完成的分数傅里叶变换是Lohmann给出的单透镜结构无法实现。 相似文献
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通过在MP-1000绘图机上制作Polar-1n变换全息图的实践,提出一种使这种变形不变全息光学元件达到实用分辨率要求的新途径,并制得比现有同种全息光学元件分辨率高一倍左右的样品。进行光学图象识别时,通常采用的是相关匹配滤波识别法。图1为该方法的光学实验原理图。图中,L_1、L_2和L_3为普通透镜,L_4和L_5为傅里叶变换透镜,f为L_4和L_5的焦距。P_1面上部为一小孔,作为制作匹配滤波片的点光源使用,P_1面下部放置被记录物体 相似文献
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分数傅里叶变换计算全息 总被引:1,自引:0,他引:1
在计算全息和分数傅里叶变换的基础上提出了不对称分数傅里叶变换计算全息和双随机相位不对称分数傅里叶变换计算全息。在这种方法中,首先用一随机相位函数乘以输入图像信息,然后沿x方向实施α级次的一维分数傅里叶变换,再乘以第二个随机相位函数,最后,沿y方向实施β级次的一维分数傅里叶变换。采用迂回位相编码法对变换后的结果编码,绘出计算全息图。为了恢复原始图像,需要知道变换级次和随机相位函数。利用这种方法进行图像加密,使加密图像的密钥由原来两重增加到四重,从而提高了系统的保密性能。 相似文献
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Through the use of anamorphic focusing, we present a method for generating broadband noncollinear optical parametric amplification in signal regions lacking a broadband phase-matching condition that is ideally suited for narrowband pump sources, herein based on an erbium-doped fiber oscillator. With a short focal length cylindrical lens to enhance the phase-matching condition and a long focal length cylindrical lens in the orthogonal plane to limit the pump power in the amplifying beta barium borate crystal, we amplify pulses in the blue-green spectral region with over 100 THz (~3500 cm(-1)) bandwidth. The amplified signal is subsequently compressed to 9.5 fs, near the transform limit. 相似文献
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As known, it is important for the propagation of Gaussian beams in optics. In this paper, based on the expanding a hard-edge circular aperture function as a finite sum of complex Gaussian functions and the scalar Rayleigh-Sommerfeld diffraction formula, an approximation analytical solution for Gaussian beams propagating through the anamorphic fractional Fourier transform system with an eccentric circular aperture is performed. Then, the detailed numerical calculation for the two-dimensional Gaussian beams in the above-mentioned optical system is presented. The simulation also shows that different location and size of aperture result in the change of diffracted field, including location, intensity and width. All these characteristics help us understand Gaussian beams propagation better. 相似文献
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A new scheme to improve the spectral resolution of grating-based spectrometers for diffuse light is proposed and demonstrated. It exploits an anamorphic transformation that reduces the beam divergence in the direction of the grating grooves while increasing the divergence in the orthogonal direction to improve the spectral resolution without any loss of light. Up to 12-fold improvement in the spectral resolution was obtained. 相似文献
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《Infrared physics》1987,27(2):125-133
Previous analyses of the SPRITE detector signal-to-noise performance have ignored the effect of the increasing carrier density along the filament due to integration of the background flux and have consequently assumed the recombination probability of excess carriers, the electric field and the ambipolar velocity all to be constant. In this paper a more exact analysis is presented, and it is shown that with the lower carrier density and longer lifetime cadmium-mereury-telluride now becoming available, significant benefits in detectivity can be obtained by correct choice of the device geometry. Expressions are given from which the optimum length and taper functions can be determined for different system scan speeds and optical apertures. It is shown that anamorphic optics can increase the achievable detectivity in addition to improving the modulation transfer function. 相似文献
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New experimental results to demonstrate that the annoying DC in the reconstructed wavefronts from in-line holograms could
be successfully eliminated are presented in this paper. The complete elimination of DC has been achieved by making proper
use of a Mach-Zehnder interferometer. The results for an in-line hololens and an in-line Fourier transform hologram are discussed.
Contribution No. 8 from Laboratories for Coherent Optics and Electrooptical Research. 相似文献
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A prism anamorphic system for Gaussian beam expander 总被引:1,自引:0,他引:1
T. Kasuya T. Suzuki K. Shimoda 《Applied Physics A: Materials Science & Processing》1978,17(2):131-136
Basic properties are given of the prism anamorphic expander of a Gaussian beam composed of a couple of prisms in tandem. Its
shorter overall length for a given expansion, relative ease of optical adjustment, a sharp selection of polarization component,
and rather small inclusive dispersion make it an excellent beam expander in a specific laser cavity. The design principle
is presented of the prism system with a grating for an anastigmatic optical resonator for a dye laser of narrow linewidth
and of short pulse duration. 相似文献
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We demonstrate low-loss anamorphic transitions between circular and rectangular fiber cores with aspect ratios up to 5:1, and hence improved coupling from a diode laser by using only a spherical lens. Differential hole pressurization and localized heating of a stock photonic crystal fiber inflates the holes at different rates. Some holes are plugged in the fiber end face where pressure is applied, so they remain at ambient pressure. Alternatively, holes of different sizes expand at different rates because the effective pressure due to surface tension differs. 相似文献