Diffraction in the Micro Structure Test and its Inhibition

In the optical test of MEMS sensors, diffraction is often an unfavorable influence to the image. This paper focuses on this problem and tries to give more detailed analyses as well as some practical measures. A coordinate system for the diffraction analyses is established and the general diffraction models are presented based on the scalar analyses. The micro reflectors array can be regarded as a diffraction screen. The diffraction pattern can be obtained based on the Kirchhoff theory. We give the corresponding equations and the diffraction pattern distribution. Based on the results, we mainly analyzed two types of diffraction reflectors, which are slim reflectors and the micro rectangle reflectors. The diffraction spectrum amplitude function of both the slim reflectors and the rectangle micro-reflection array are obtained. Finally, some analyses and discussions of the diffraction problem in considerations of the MEMS structures design are presented.