分频光栅的衍射特性及误差分析

 基于标量衍射理论推导出了分频光栅的各级衍射效率公式，分析了分频光栅的衍射特性，发现入射光波在满足相应的相位延迟条件时，能被分频光栅以最大效率衍射进３个中央级次中的某一级。分析和比较了两种制作工艺中的刻蚀深度误差、占空比误差对衍射效率的影响。在惯性约束聚变（ICF）应用中，对于同一要求的３倍频光的衍射效率范围，两种工艺的刻蚀误差容限是相同的，但是两种工艺的相同刻蚀误差却带来不同的衍射效率。在不计其它误差时，占空比误差不会对３倍频光的衍射效率产生影响，但可以对基频光和2倍频光产生相反的影响，占空比误差还可以使基频光和2倍频光的主要衍射级次的效率都降低，同时增大它们的0级衍射效率。

Diffraction characteristics and analysis on errors of color separation grating

An analytical expression of diffraction efficiency of color separation grating (CSG) was deduced from the scalar diffraction theory and Fourier optics. Moreover, the relation between diffraction efficiency and phase delay was analyzed. If the phase-delays brought by different parts of CSG meet corresponding conditions, the incident wave will be diffracted into one of the three central diffraction orders with highest efficiency. In addition, some errors, including etched depth error and duty cycle error, induced by two different fabricating processes were analyzed and compared. In ICF studies, CSG, which are fabricated by the two processes, have the same fluctuation range in diffraction efficiency for the third harmonic when tolerated etched errors are the same. Duty cycle errors can bring opposite in fluence on fundamental frequency light and its second harmonic as well as make them decline in their primary order but rise in the 0 order.