共查询到20条相似文献,搜索用时 15 毫秒
1.
N. Demoli 《Optics & Laser Technology》1994,26(2)
The dependence of the output correlation signal on the filter parameters, filter types, and signal types in matched filtering is discussed. On the basis of the established filter criteria—the signal-to-noise ratio, peak-to-sidelobe ratio, and diffraction efficiency—a new measure is introduced giving an overall estimate of the feasibility of filters. According to that single measure, various filter types are compared and selected by numerical experiments. 相似文献
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在光电混合匹配滤波相关识别系统中,由于输入图像的频谱与匹配滤波器的形成方式不同,不能直接实现对应频率成份的准确对准。这个问题需要通过对匹配滤波器进行缩放来解决。根据透镜的傅里叶变换性质和计算全息理论,分别推导出输入图像的频谱的表达式和滤波空间光调制器加载了匹配滤波器后的透射函数的表达式,并根据这两个表达式得到匹配滤波器的缩放比例的公式,然后在实际的光学识别系统中对根据该公式计算的缩放比例进行了验证。实验结果表明,在该缩放比例下,相关峰的质量有较大改善,这说明此时输入图像的频谱与匹配滤波器对应频率成份实现了较好地对准。 相似文献
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In the present paper, the effect of transverse and longitudinal vibrations of a spatial filter in signal detection by optical
matched filtering has been investigated. It has been assumed that the noise spectral density is uniform. Degradation in the
performance of such an optical information processing system has been illustrated graphically. It is noticed that the effect
of transverse vibrations is more severe than that of longitudinal vibrations. Results have also been compared with those obtained
by Van der Lugt for the case of static displacement of a spatial filter. 相似文献
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The nonlinear Schrödinger equation which governs the dynamics of two-dimensional spatial solitons in Kerr media with periodically varying diffraction and nonlinearity has been analyzed in this paper using variational approach and numerical studies. Analytical expressions for soliton parameters have been derived using variational analysis. Variational equations and partial differential equation have been simulated numerically. Analytical and numerical studies have shown that nonlinearity management and diffraction management stabilize the pulse against decay or collapse providing undisturbed propagation even for larger energies of the incident beam. 相似文献
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基于矩孔光学傅里叶变换的匹配滤波器缩放比例标定方法研究 总被引:1,自引:1,他引:0
为了使待识别目标的傅里叶变换频谱与匹配滤波器频谱分布严格重合,提出了一种基于矩孔图像光学傅里叶变换的匹配滤波器缩放比例标定方法。针对范德卢格特型光学相关器,在分析场景空间光调制器傅里叶变换频谱分布的基础上,以矩孔图像的频谱间距作为基准标定匹配滤波器的缩放比例;并利用焦距为400mm的傅里叶透镜作为一个实例,计算出其匹配滤波器缩放比例为1.068,对标定结果进行了实验验证。结果表明,此方法适用于范德卢格特型光学相关器中匹配滤波器的缩放比例标定,能够有效提高相关峰的能量和信噪比。 相似文献
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This paper obtains the exact analytical solution of atomic
Raman--Nath diffraction in the coordinate representation and
discusses the influence of different initial conditions and detunings
on the atomic spatial population distribution. The phase difference
between the dipole matrix element and initial atomic population may
influence the atomic spatial population distribution after
diffraction, which has never been discussed before as far as we know.
It offers a method to measure the phase by the spatial population
distribution, which is interesting in the study of quantum optics. 相似文献
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空间频率对透射式全息图衍射率的影响 总被引:1,自引:1,他引:0
为研究干涉条纹空间频率与透射式全息图衍射率的关系,在相同条件下,拍摄以平面波、发散的和会聚的球面波分别作参考光、物光的透射式全息图,通过实验测量其衍射效率,同时计算了干涉条纹的空间频率。然后以会聚的球面波为物光,平面波为参考光,分别改变入射角和球面波会聚点到记录面的距离制作另外4块透射式全息图,并计算了它们的空间频率,测量了其衍射效率。结果表明:在相同条件下制作透射式全息图时,衍射效率只由空间频率决定,与使用何种参考光和物光无关,空间频率仅随参考光和物光的夹角变化而变化。 相似文献
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Abstract: In this paper, we consider the transformation of a ray beam as it passes through an optical system containing a
glass plate with parallel surfaces inclined to the optical axis at the Brewster’s angle, by investigating the effects of the
optical system on amplitude and phase distributions. By applying generalized matrix optics and diffraction integrals and considering
the influence of a quarter of a wavelength of aberration on the transmitted amplitude and phase distributions at the focus
of a de-collimating lens, we find that the central peak amplitude descends from 1.0 to 0.8 and the phase distortion is less
than π/2. The general feature of the amplitude distribution shows an elongation along the y-axis perpendicular to the optical
axis in the direction of tilt of the inclined plate, and conforms to the inclination direction of the glass plate.
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We propose and demonstrate an all-optical analog-to-digital conversion system with a spatial coding method using a designed
filter. To make available codes more flexible, the design technique for a computer-generated hologram is introduced to our
spatial coding scheme. By designing the spatial coding filter appropriately, this coding scheme enables us to output various
digital signals as spatial patterns. By combining this coding method with the optical quantization method using soliton self-frequency
shifting in a fiber, the proposed system converts analog sampled signals into arbitrary digital signals. Preliminary experimental
results show that 3-bit Gray codes are successfully output as spatial patterns using the designed spatial coding filter. 相似文献
17.
The dynamical evolution and stability of
bright dissipative holographic solitons in biased photorefractive materials
in which the self-trapping beam obtains a gain from the pump beam via two-wave
mixing has been investigated numerically. Results show that these solitons are stable relative to small
perturbations. Adjusting some system parameters, such as the bias field and
the angle between beams, can easily control the generation of such solitons.
Potential applications in optical switches or repeaters are discussed. 相似文献
18.
We present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator
(SLM). The proposed method is based on optical diffraction from pixelated LC panel that has been modeled as a two-dimensional
array of rectangular apertures. A novel yet simple, two-plane measurement technique is implemented to circumvent the difficulty
in absolute distance measurement. Experimental results are presented for electrically addressed twisted nematic LC-SLM removed
from the display projector. 相似文献
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SUN PingPing LIU DeAn ZHANG YanLi LI XiaoYan ZHANG Yan & ZHU JianQiang National Laboratory on High Power Laser Physics 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
The theoretical model of spatial noise passing through a spatial filter is established in high power laser system under the small signal approximation. The transmission characteristic for a noise signal passing through spatial filters with different magnifications is analyzed by numerical simulation, according to the actual structure of the high power laser system. The results show that the spatial modulation period of low-frequency noise getting through the pinhole will be proportional to the magnification... 相似文献
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Yusuf Z. Umul 《Optics & Laser Technology》2008,40(6):769-774
A novel potential function is introduced by using the modified theory of physical optics integrals for a perfectly conducting half-plane. The function is valid for arbitrary aspects of observation. The line integration of these functions gives the total scattered fields. The method is applied to the problem of diffraction of plane waves by an opaque half-plane for oblique incidence. 相似文献