部分相干光学成像系统的光学传递函数和像质评价准则

根据光学成像理论，建立了部分相干成像光学系统的光学传递函数。该函数与非相干成像光学系统传递函数相同，因而部分相干成像和非相干成像两者的光学系统波面像差公差标准也是相同的。这一点解释了显微镜光学系统的光学设计惯用法则：镜头像差公差标准的选择，并不因为采用成像照明方式的不同而有所差异。     

Synthesis of spatial coherence

The mutual intensity function plays a major role in characterizing quasi-monochromatic, partially coherent optical signals. We propose to use the mutual intensity as a carrier of information to avoid speckle noise in coherent illumination systems and to permit the use of complex functions that are prohibited spatially incoherent sources. To do this we require methods for encoding the information as a coherence function. An optical system for synthesizing a beam with a given mutual intensity function is proposed. The optical system permits the synthesis of any desired mutual intensity function. The illumination is supplied by a quasi-monochromatic, spatially incoherent source. Experimental results demonstrate the performance of this system for several cases.     

Optical filtering

This contribution deals with phase and amplitude filters used in coherent, partially coherent and incoherent illumination both for improvement of optical images and for detection of similarities (correlation). Other types of filters such as intensity filters, phase only filters etc. will be also discussed where appropriate. Most of the space, however, will be devoted to optical filtering in coherent illumination.     

光源编码的白光散斑剪切干涉计量术

本文提出了一种用非相干光源照明进行剪切干涉计量的方法—光源编码的白光散斑剪切干涉计量术.它采用光栅对光源进行编码以提高空间相干性,使物体的两个剪切像的波面部分相干叠加,以实现剪切干涉.     

象面斑纹噪声相乘性的进一步探讨

本文导出了部分偏振斑纹象强度的n阶矩,考察了部分偏振象面斑纹噪声相乘性的统计学论据,并讨论了部分偏振斑纹象乘法模型的均方误差。最后讨论了N个等强度照明的独立直线偏振斑纹象非相干叠加时乘法模型的有效性。 关键词：     

Determination of the resolving power of optical systems in the formation of speckle images

Relations for the calculation of the limiting resolvable spatial frequency of a speckle image of a line mira used as a test object in the determination of the optical power of optical systems are presented. The influence of the speckle structure on the extraction of information about the shape of the object observed from the image recorded is taken into account by using the equivalent modulation transfer characteristic of the optical system than determines the transfer of spatial frequencies of the envelope of the speckle image and the threshold characteristic of speckle noise conditioned by fluctuations of the amplitudes of individual speckles. Conditions, in which the prevailing influence on the quality of the image recorded is exerted by the speckle structure, atmospheric phase distortions, and discretization noise, are determined.     

四光束剪切相干成像目标重构算法研究

针对传统剪切光束成像技术的准实时性问题,提出用口字形排布的四束光代替传统L形三束剪切光照射目标,研究了四光束剪切相干成像目标重构算法.只需单次测量就能同时重构出四幅目标图像,减少了用于降低散斑噪声、获取高质量图像所需的测量次数,同时大大减少了多组发射时的光束切换次数,提高了成像效率.在算法实现中,通过最小二乘法恢复出四组波前相位,利用散斑幅值的简单代数运算恢复波前幅值,从而重构出目标图像.仿真结果表明,与传统方法相比,在图像质量相同的前提下,本文方法所需的数据采集时间减少了至少1/2,不但提高了目标重构效率,还可为远程运动目标的成像识别提供更好的手段.     

Wide-field fluorescence sectioning with hybrid speckle and uniform-illumination microscopy

We describe a method of obtaining optical sectioning with a standard wide-field fluorescence microscope. The method involves acquiring two images, one with nonuniform illumination (in our case, speckle) and another with uniform illumination (in our case, randomized speckle). An evaluation of the local contrast in the speckle-illumination image provides an optically sectioned image with low resolution. This is complemented with high-resolution information obtained from the uniform-illumination image. A fusion of both images leads to a full resolution image that is optically sectioned across all spatial frequencies. This hybrid illumination method is fast, robust, and generalizable to a variety of illumination and imaging configurations.     

Full-field heterodyne interference microscope with spatially incoherent illumination

A heterodyne interference microscope arrangement for full-field imaging is described. The reference and object beams are formed with highly correlated, time-varying laser speckle patterns. The speckle illumination confers a confocal transfer function to the system, and by temporal averaging, the coherence noise that often degrades coherent full-field microscope images is suppressed. The microscope described is similar to a Linnik-type microscope and allows the use of high-numerical-aperture objective lenses, but the temporal coherence of the illumination permits the use of a low-power achromatic doublet in the reference arm. The use of a doublet simplifies alignment of the microscope and can reduce the cost. Preliminary results are presented that demonstrate full-field surface height precision of 1 nm rms.     

Studies on the spectral width,monochromatic degree and spectral resolving power of prism monochromator

The angular width and geometric line width in the spectral plane for the output incoherent imaging spectral line are discussed respectively on the basis of structure of prism monochromator, the relationship between the spectral width and line width of output incoherent imaging spectral line in the spectral plane is presented. The expression of monochromatic degree of output light in the exit slit plane is presented. The spectral resolving power of incoherent imaging spectral line and coherent imaging spectral line of the diffractive waves are discussed respectively, and the expressions of the spectral resolving power are presented respectively.     

彩色漫射物体的压缩全息层析成像

漫射物体的压缩全息利用其非相干散射密度函数在统计意义上满足稀疏先验这一假设,可以从多幅散斑图案实现漫射物体的层析重建,避免了散斑和不同平面的散焦图像之间的串扰。将单波长照明条件拓展到红、绿、蓝三色波长,提出一种新的适用于彩色漫射物体的压缩全息层析成像方法,搭建多波长照明条件下漫射物体的层析成像模型,并通过解压缩推理方法有效地分离不同平面的三维非相干密度函数。数值模拟实验表明,所提方法可以在多幅二维彩色散斑图案中成功进行彩色层析漫射物体的压缩重建,有效地抑制了散斑效应以及不同平面的散焦图像之间的相互串扰。     

非相干照明条件下的ptychographic iterative engine成像技术

在传统多波长相干衍射成像理论的基础上提出适用于 X-射线和电子束等非相干光源照明成像的改进多波长ptychographic iterative engine 方法, 同时将小孔形状和照明光谱信息用于叠代计算, 可以在非相干照明条件下精确重建出物体的强度透射像和相位透射像, 并对光源带宽对重建精度的影响进行了分析, 对于解决如何在非相干照明条件下对大尺寸物体进行精确相位成像的问题具有较好的科研和实用价值.     

Image-plane speckle in partially coherent illumination

Expressions are derived for the first and second order statistical properties of speckle formed in the image of a diffuse object when the illumination is both temporally and spatially partially coherent. Sunlight falls into this illumination category, and we are therefore able to deduce conditions under which sunlight speckle will show best contrast.     

Novel Ghost Imaging Method for a Pure Phase Object

We propose a novel ghost imaging scheme which is especially served to a pure phase object. A spatially incoherent beam is mixed with a coherent beam of the same frequency field by a beamsplitter. Then we perform the ghost imaging scheme using the mixed beam. Our theoretical result shows that this approach is capable of reconstructing a pure phase object in joint-intensity measurement. The visibility of the images is also analysed for two pure phase objects, an optical wedge and a phase grating.     

Interaction of nonlocal incoherent spatial solitons

We investigate numerically the interaction of nonlocal incoherent spatial solitons in strongly nonlocal kerr media based on the coherent density approach. Numerical simulations show that the incoherent soliton position is very similar to the case of coherent soliton, and show that the incoherence plays an important role in the soliton interaction, while the role of other parameters such as the phase difference, the separation, the extent of nonlocality and the input power play in the interaction is very similar to the case of nonlocal coherent soliton. Some interesting numerical examples are presented to illustrate their interaction behavior further. Pertinent physics features are addressed.     

Formation of lateral-shift speckle interferograms in diffusely scattered fields

The formation of lateral-shift speckle interferograms that characterize the axial wave aberrations of the optical system used in the coherent matte-screen illumination channel is analyzed in the Fresnel approximation based on coincidence of the objective speckle fields of two exposures in the photoplate plane. It shown theoretically and in experiment that speckle-interferometer sensitivity is doubled at a given lateral shift. Tomsk State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 36–42, September, 1996.     

Improving coherent averaging line spectrum detection with phase interpolation and compensation

For the purpose of resolving the problem of performance deterioration introduced by inaccurate phase compensation in existing coherent averaging line spectrum detectors,a modified coherent detector is proposed.The three point interpolation in frequency domain is applied to obtain accurate estimate of phase difference between segments when the segmented length is not an integral multiple of the signal period.Then the segmented data are multiplied by a complex coefficient to remove the phase difference and synchronize the phases of all the segments before coherent averaging.Theoretical analysis shows that there will be a gain of3.9 dB at most by using the modified detector.The detection performance of the incoherent averaging power spectrum detector(AVGPR),the phase coherent averaging detector,the modified coherent averaging detector are compared with each other by computer simulations.The results coincide basically with the theoretical analysis,which show the superiority of the modified detector to the former two detectors.     

Coherent and incoherent combining of fiber array with hexagonal ring distribution

Beam combining of fiber array with hexagonal ring distribution is studied in detail. The theoretical analysis and numerical calculation results are given to illustrate the propagation properties of the resulting beam through free space. A comparison between the coherent and the incoherent case shows that high peak irradiance and good beam quality for coherent combining can be obtained in the far field. The effect of phase errors and the beam quality M² factor are also studied. Results indicate that the element numbers should be increased to achieve high power and the space between adjacent elements should be reduced to maintain good beam quality, which is basically the same for both coherent and incoherent beam combining.     

Spatially incoherent illumination as a mechanism for cross-talk suppression in wide-field optical coherence tomography

Comparison of two illumination modes for wide-field optical coherence tomography has revealed that spatially coherent illumination generates coherent cross talk, causing significant image degradation, and that spatially incoherent illumination, with an adequate interferometer design, provides an efficient mechanism for suppression of coherent cross talk. This is shown by comparison of a pulsed laser with a thermal light source for a U.S. Air Force resolution target covered with a scattering solution made from microbeads as well as for an ex vivo tooth.