非球面Ronchi检测的误差分析

为了较高精度地检测大型非球面面形,需要分析检测装置对测量误差产生的影响。基于Ronch i检测法,将正弦光栅代替Ronch i光栅应用在非球面反射镜的检测上,采用同步相位探测技术和几何原理获得所有被测点的面形偏差梯度信息,然后利用区域波前重构法恢复面形偏差,进而重建被测面形。利用此方法首次分析了叠栅条纹图、非球面度、光栅对比度对重建被测面形的影响。数值结果表明,条纹图的重叠和光栅的对比度均对非球面的检测精度有影响,重建面形误差随着被测面形非球面度的增加而增大。对测量误差的分析可为Ronch i检测装置的设计提供有效、可靠的依据。

Error Analysis of Ronchi Test for Aspherical Mirrors

In order to measure aspherical surfaces more accurately, the influence of test device on measurement error was analyzed in this paper. Instead of ronchi grating, sinusoidal grating was used to test aspherical mirrors based on the Ronchi method. By synchronous phase detection technology and geometrical theory, shape deviation gradients of all tested points could be obtained. Then the surface of the tested mirror was reconstructed after restoring shape deviations using area wave-front reconstruction method. The influence of combination fringes, asphericity and grating contrast on reconstructed tested surface were presented firstly. The numerical results showed that both the combination fringes and grating contrast affect the testing accuracy of aspherical surface, and the error of reconstruction increases with asphericity. The results may provide an affective and reliable basis for Ronchi test device.