Some Problems on Reconstruction of Soft X -ray Hologram with Visible Light

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非球面目镜

由于孔径光栏（出瞳）在目镜光学系统的外面，所以光学系统的畸变矫正格外地困难。消除畸变的最佳方法是采用非球面。本文依据三级像差理论，对新颖的非球面广角目镜的光学系统设计作了描述，并给出设计的结果和数据。     

Irradiance map of an apertured Gaussian beam affected by coma

The Gaussian amplitude of a laser beam incident on an optical system affected by coma is expanded until the fourth order. This expansion is included in the Huygens-Fresnel integral calculation to obtain the amplitude and irradiance distribution on the focal plane of an optical system affected by coma. The analytical results obtained here are compared with a previous model of a comatic Gaussian beam. Appropriateness of the analytical model is also validated by the fitting with experimental data.     

A note on grating based soft X-ray monochromators

A few facts related to the aberrations for toroidal and plane gratings are presented. Some design aspects of the plane grating-based monochromator devised by Petersen (1982) are discussed. We also point out that for a cylindrical grating astigmatic correction can be reduced and suggest that following Petersen’s scheme some improvements in the monochromator performance could be achieved with such a grating.     

2IV^m-p设计的弱最小低阶混杂与纯净效应准则等价的条件

该文给出了2IVm-p设计包含最多纯净两因子交互效应与该设计具有弱最小低阶混杂等价的几个条件．并在文章的末尾给出了一组既具有弱最小低阶混杂又包含最多纯净两因子交互效应的2IVm-p设计．     

Aberration correction and its automatic control in scanning electron microscopes

An automatic aberration correction method has been implemented in scanning electron microscopes (SEM). Necessity of the automatic aberration correction is discussed. The procedure of the automatic aberration correction is explained in detail, where deconvolution techniques are used in order to extract probe information from SEM images. Due to the precise digitization and the usage of proper combinations of correction fields, linearity has been found between the amplitude of each aberration and the corresponding field strength. Experimental results are shown which demonstrate that the aberrations are corrected automatically by a linear feedback control method. After the automatic aberration correction, the image quality has been improved drastically.     

Effect of Comatic Aberration on the Propagation Characteristics of Laguerre--Gaussian Beams

Seidel comatic aberration is an important cause of deformation for a Laguerre--Gaussian (LG) beam. In addition, mono-axial comatic aberration, whose phase modulation depends only on one transverse coordinate, is also an important cause of beam deformation. Deformation of an LG beam by such aberrations is analyzed through numerical simulation based on the angular spectrum method. It is also shown that for holographically generated LG beams quadratic spatial variation of grating pitch can produce seidel and mono-axial comatic aberrations. An example of an experimentally generated LG beam with mono-axial comatic aberration is reported.     

哈特曼夏克传感器的泽尼克模式波前复原误差

利用哈特曼－夏克传感器测量圆孔径内波像差时，通常使用泽尼模式复原算法。推导了一般情况下哈特曼－夏克传感器泽尼克模式波前复原误差的计算公式。用哈特曼－夏克传感器测量一个像差板的随机静态像差，通过与ZYGO干涉仪的测量结果比较，得到不同泽尼克模式复原阶数下的波前复原误差的实验结果，并与理论计算结果进行了对比。     

离焦对散斑测量灵敏度的影响

本文分析了象差函数对光学传递函数的性态影响,指出在用白光主观散斑法测量曲面变形时,由于成象系统不能对曲面上各点同时对焦,各物点有不同程度的离焦,而造成光学传递函数对频率响应的下降,有效截止频率的降低,从而影响其测量灵敏度的提高。