合成孔径激光成像雷达(Ⅲ):双向环路发射接收望远镜

提出了一种用于合成孔径激光成像雷达的双向环路结构的发射接收望远镜,双向环路包括发射4-f转像系统、接收4-f转像系统和独立的望远镜。发射通道中设置离焦和相位调制平板偏置,接收通道中设置离焦和相位平板偏置。控制发射离焦量,发射相位调制函数,接收离焦量,接收相位调制函数,用同一个望远镜可以同时实现空间二次项相位附加偏置的激光发射和消除目标点散射回波接收波面像差的离焦光学接收,并产生雷达运动方向上合适的和可控制的相位二次项历程,从而实现孔径合成成像。详细介绍了系统设计,给出了从发射到光电外差接收的全过程传输方程。

Enlarging the depth of focus by filtering in the phase-space domain

The ambiguity function was employed as a merit function to design an optical system with a high depth of focus. The ambiguity function with the desired enlarged-depth-of-focus characteristics was obtained by using a properly designed joint filter to modify the ambiguity function of the original pupil in the phase-space domain. From the viewpoint of the filter theory, we roughly propose that the constraints of the spatial filters that are used to enlarge the focal depth must be satisfied. These constraints coincide with those that appeared in the previous literature on this topic. Following our design procedure, several sets of apodizers were synthesized, and their performances in the defocused imagery were compared with each other and with other previous designs. (c) 2005 Optical Society of America.

大型光学镜子热弹性变形的有限元分析

简述了利用ANSYS软件对大型光学镜子热弹性变形进行有限元分析的一般方法，强调了在分析过程中应该注意的一些问题和实用技巧，并给出了一个分析透镜重力变形的实例。

Measurement of the diffraction-limit wavefront with double-shearing interferometers

In order to measure the diffraction-limit wavefront, we present three types of common-path double-shearing interferometers based on the theory of double shearing. Two pairs of half-aperture or whole-aperture wedge plates are used to introduce opposite tilt to realize the double-shearing function. By comparing the fringe widths in two fields, the marginal wavefront aberration can be obtained. In the paper, we give three different configurations: half-aperture configuration, whole-field configuration and double-interferometer configuration. The half-aperture configuration has the features of high sensitivity, stabilization and easy alignment. For the whole-field configuration, the interference fringes are displayed in two whole fields. Consequently, the divergent or convergent characteristic and aberration types of a wavefront can be identified visually. The whole-field configuration can be changed to the double-interferometer configuration for continuous test. Both small and large wavefront aberrations can be measured by the double-interferometer configuration. The minimum detectable wavefront aberration (W-0)(min) comes to 0.03 lambda. Lastly, we present the experimental results for the three types of double-shearing interferometers.

Coma measurement using a PSM and transmission image sensor

As feature size decreases, especially with the use of resolution enhancement technique, requirements for the coma aberrations in the projection lenses of the lithographic tools have become extremely severe. So, fast and accurate in situ measurement of coma is necessary. In the present paper, we present a new method for characterizing the coma aberrations in the projection lens using a phase-shifting mask and a transmission image sensor. By measuring the image positions at multiple NA and partial coherence settings, we are able to extract the coma aberration. The simulation results show that the accuracy of coma measurement increases approximately 20% compared to the previous straightforward measurement technique. (c) 2005 Elsevier GmbH. All rights reserved.

Radius of curvature measurements for laser beams: A simple method

A simple method for measuring the radius of curvature of laser beams is introduced. It has been developed to estimate the astigmatic aberration of a diode laser. Compared with the interferornetry, this method is convenient and straightforward. (c) 2005 Elsevier GmbH. All rights reserved.

Coma measurement by use of an alternating phase-shifting mask mark with a specific phase width

The correlation between the coma sensitivity of the alternating phase-shifting mask (Alt-PSM) mark and the mark's structure is studied based on the Hopkins theory of partially coherent imaging and positive resist optical lithography (PROLITH) simulation. It is found that an optimized Alt-PSM mark with its phase width being two-thirds its pitch has a higher sensitivity to coma than Alt-PSM marks with the same pitch and the different phase widths. The pitch of the Alt-PSM mark is also optimized by PROLITH simulation, and the structure of p - 1.92 lambda/NA and pw = 2p/3 proves to be with the highest sensitivity. The optimized Alt-PSM mark is used as a measurement mark to retrieve coma aberration from the projection optics in lithographic tools. In comparison with an ordinary Alt-PSM mark with its phase width being a half its pitch, the measurement accuracies of Z(7) and Z(14) apparently increase. (C) 2009 Optical Society of America

Computational Microscopy: Breaking the Limit of Conventional Optics

Computational imaging is flourishing thanks to the recent advancement in array photodetectors and image processing algorithms. This thesis presents Fourier ptychography, which is a computational imaging technique implemented in microscopy to break the limit of conventional optics. With the implementation of Fourier ptychography, the resolution of the imaging system can surpass the diffraction limit of the objective lens's numerical aperture; the quantitative phase information of a sample can be reconstructed from intensity-only measurements; and the aberration of a microscope system can be characterized and computationally corrected. This computational microscopy technique enhances the performance of conventional optical systems and expands the scope of their applications.

透过检测中的准直镜精度容限

在干涉检验过程中, 被检元件的面形误差检测精度受到干涉仪系统结构的影响, 从而降低测量结果的可靠性。为了得到较高的检测精度, 必须对检测系统进行分析, 建立测量误差和系统结构的关联度。根据菲涅耳衍射近似理论, 就菲佐干涉仪中的准直镜和标准镜面形误差对透过检测的影响进行了研究。通过对波前相位传递情况的分析, 得出波前误差和系统结构参量的相关性, 去除空腔系统误差, 优化结构参量, 并建立准直镜误差容限表达式。经计算得出, 当被检面形变误差为0.2λ时, 测试误差可以达到0.02λ, 而对准直镜的面形误差要求

侧面抽运板条激光介质动态热畸变测量方法

研究了基于干涉测量激光介质热畸变的原理,利用CCD摄像机记录干涉条纹并通过计算机图像处理,来测量板条激光介质动态热畸变的方法。对采集得到的干涉条纹进行图像处理,提出了一种简单快速提取条纹中心的算法。通过分析、计算干涉条纹的移动,得到抽运过程中板条激光介质的动态热畸变情况,为动态补偿激光介质热效应提供了可能。实验采用了N31磷酸盐激光玻璃作样品,得到了加热过程中激光玻璃内部的温度分布,误差约为3%,验证了该测量方法的可行性。

扫描型哈特曼检测装置研究

在传统哈特曼检验法基础上研制成功一种扫描型哈特曼检测新装置。可对最大口径为Ф300mm的聚焦镜在全口径范围内进行采样测量。该检测装置由大口径标准平行光管、扫描式哈特曼光阑、被俭聚焦镜、CCD摄像机及计算机组成。在水平和垂直两个径向上开有等间距排列且相互错开半个间距的小孔。并且在步进电机的驱动下绕光轴旋转。可对被检聚焦镜进行全口径连续采样。对有效口径为夺154mm的斐索平面干涉仪非球面准直物镜的球差及焦斑能量集中度进行了测量。进而由球差计算得到了波像差。并用干涉法对该准直物镜进行了测量。球差的理论值与测量值

靶镜光学质量检测技术的研究

提出了一种利用扫描型哈特曼检测装置检验靶镜光学质量的技术.该装置对传统哈特曼检验装置的光阑进行了改进,通过扫描型哈特曼光阑的旋转扫描,可对被检靶镜全口径范围内连续采样.利用该扫描型哈特曼检测装置对一块口径为φ270 mm的非球面靶镜的能量集中度和波像差进行了检验,其结果与激光数字波面干涉仪的测量结果相吻合,其中能量集中度的相对测量误差为7.7%,波像差的相对测量误差为10.2%,验证了该检测技术的有效性.

用于钕玻璃啁啾脉冲放大系统光谱整形的多层介质膜反射镜

在千焦拍瓦高功率啁啾脉冲放大系统设计中,为了尽量消除增益窄化和增益饱和效应的影响,同时尽可能提高高功率激光输出脉冲信噪比参数,激光脉冲时空和光谱的整形问题备受关注.提出一种光谱整形新方法,利用特定结构的多层介质膜反射镜,可实现对大能量高功率啁啾脉冲钕玻璃放大系统中啁啾脉冲的光谱整形.研究结果表明,只要合理选择多层介质膜系的结构参数,可有效地控制其反射率分布,且在保证反射相位基本不变的条件下其调制度可超过60%.针对钕玻璃1053nm波长设计而成的光谱整形反射镜,反射带宽可达到196nm,色分辨率约为0.1nm,在几十纳米波长范围所对应的相位偏差小于12mrad,相当于λ/524,能够满足"神光Ⅱ"千焦拍瓦改造的技术指标要求.

Genotoxic effect of nickel chloride and zinc sulphate on fish Hypophthalmichthys molitrix

The present investigation is to assess the genotoxic potential of nickel chloride and zinc sulphate on gill cells of silver carp Hypophthalmichthys molitrix. Fishes were exposed in sublethal concentration of nickel chloride 5. 7 mg/1 and zinc sulphate 6.8 mg/1, and sampled at 10, 20 and 30 days. Nickel chloride and zinc sulphate treated fishes exhibited an apparent increase in the aberration frequency and a decrease in the mitotic index as compared to control. Acentric fragment, chromatid break, endoreduplication, chromatid gap, centromeric fusion, ploidy, sticky plate, dicentric chromosome, clumping and partial sticky plates were some of the abnormalities observed. The chromosomal aberrations in the treated fishes were significant compared to control.

Use of wavefront encoding in optical interconnects and fiber switches for cross talk mitigation

A technique of cross talk mitigation developed for liquid crystal on silicon spatial light modulator based optical interconnects and fiber switches is demonstrated. By purposefully introducing an appropriate aberration into the system, it is possible to reduce the worst-case cross talk by over 10 dB compared to conventional Fourier-transform-based designs. Tests at a wavelength of 674nm validate this approach, and show that there is no noticeable reduction in diffraction efficiency. A 27% spot increase in beam diameter is observed, which is predicted to reduce at longer datacom and telecom wavelengths. © 2012 Optical Society of America.