倍频光栅的莫尔条纹研究

用傅里叶频谱分析方法研究了横向莫尔条纹中一个光栅倍频时莫尔条纹的变化，论证了倍频光栅形成的莫尔条纹方向与等周期两RoncK光栅形成的莫尔条纹方向相同，其周期与两小周期光栅的莫尔条纹周期相同，其对比度随倍率的增加而减小的特点，呈现莫尔条纹效应的主要是等栅距光栅和二倍频光栅，介绍了产生倍频光栅的一些方法，如采用滤波的方法，消去光栅的0级衍射波，形成倍频光栅；采用球面波照明光栅，形成倍频的光栅的自成像等，举例说明了其应用，这些应用表明二倍频光栅莫尔条纹可使结构紧凑，测量简单，或使分辨率提高一倍。

An approach to the Moire fringe with double frequency grating

Based on the lateral Moire fringe of the gratings, the change of Moire fringe was researched by using Fourier spectrum while the frequency of a grating was changed. The study has proved that the direction of Moire fringe formed by a grating and a double frequency gratings is the same as that of two same frequency gratings. The period is the same as the period of Moire fringe formed by two small period gratings and the contrast is decreased with the increasing of the frequency. The Moire fringe effect is formed by two same frequency gratings or a double frequency grating. It is given how to make the grating with double frequency. The double frequency grating is formed when the diffraction beams of order 0 of a grating are filtered or the self image grating with the double frequency is formed when the grating is illuminated by a spherical wave. Some applications are described. The structure is small, the measuring is simple and the resolution is increased when the lateral Moire fringes of the double frequency grating is used.