基于叠栅技术的二维亚波长周期结构成像设计

用光子学方法研究了叠栅技术中,当试件光栅被拉压和旋转后,叠栅条纹的空间周期和相对于基准光栅的取向,试件光栅被拉压后的节距等相关问题。根据衍射光波的空间周期可能大于试件光栅空间周期的特点,对二维亚波长周期结构衍射成像进行了设计研究。首先,对二维亚波长周期结构衍射物进行编码,以获得包含编码光栅空间信息的均匀波;其次,使编码得到的均匀波通过光学系统,并被放大到CCD相机所能辨识的大小;再次,经解码光栅解码,滤掉编码波,最终获得二维亚波长周期结构物的空间结构信息,达到超分辨的目的。同时,对成像过程进行了较为详尽的分析,对编码器、解码器的位置以及它们相对衍射物的取向进行了设计研究,对滤波器的选择给予了必要的说明,指出了取得超分辨成像的关键。

An Imaging Approach of Two-Dimensional Object with Subwavelength Periodic Structure Based on Moiré Technique

When the measuring grating is pulled and/or rotated relative to the reference grating, both of the spatial period and the direction of moiré fringes are studied by photonics method in moiré technique, so does the stop of measuring grating. An approach of imaging of two-dimensional object with subwavelength periodic structure is given based on the fact that spatial period of diffractive wave may be larger than measuring grating's one in moiré technique. First, two-dimensional object with subwavelength periodic structure can be encoded by a perpendicular grating so that homogeneous waves can be obtained. Second, passing through the optical system designed specially, the well-distributed waves with evanescent waves can be enlarged so that it can be recognized by CCD camera. Third, the homogeneous waves with evanescent waves can be decoded by a decoding grating. By decoding, the information of encoding grating is filtered, the image of two-dimensional object with subwavelength periodic structure can be reappeared in the image plane. By the approach given, superresolution image of two-dimensional object with subwavelength periodic structure will be obtained. Theoretical analysis and experimental design for the imaging process of two-dimensional object with subwavelength structure are given well by photonics method. At the same time, the directions of filters as well as the main factors of the imaging are discussed in the novel technique.