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。

Effects of Focusing Error on the Sensitivity of Speckle Method

It is analysed in this paper that the aberration function will reduce the high-frequency portions of OTF to such an extent that the effective cutoff is much lower than the diffraction limited cutoff. The frequency response of OTF drops rapidlyby using subjective white light speckle for curved surface deformation measurement since the image plane is out of focus. The sensitivity is quite limited by the focusing error. It is also suggested in this paper that the shortage can be overcome by means of objective white light speckle method instead.