Shack-Hartmann波前传感器非零位在轴检测离轴非球面反射镜

在离轴非球面反射镜研磨后期和粗抛光阶段,被测反射镜面形与理想面形存在着较大的偏差,表面反射率较低,采用干涉测量会因局部区域干涉条纹过密或条纹对比度过低,造成普通干涉仪无法进行全口径测量,而普通接触式轮廓仪测量精度此时已经不能满足加工要求。鉴于Shack-Hartmann波前传感器较大的动态范围和较高的测量精度,提出了采用Shack-Hartmann波前传感器非零位在轴检测离轴非球面面形,研究了该方法的检测原理并搭建了检测系统,分析了系统误差来源,并制作了用于在轴检测离轴非球面的参考波前,对两个不同加工精度的离轴非球面反射镜进行了测量,并与干涉仪的测量结果进行了对比。对比结果表明,Shack-Hartmann波前传感器的测量结果是正确可靠的,并且可以弥补轮廓仪测量和干涉仪测量的不足,从而证明了采用Shack-Hartmann波前传感器在轴检测离轴非球面的可行性和正确性。

Shack-Hartmann wavefront sensor nonnull testing off-axis aspheric surface on axis

At the end stage of the grinding process of the reflection mirror,the shape of the surface has large difference between the target shape.Especially when the mirror has a steep aspheric surface,interferometer may not be possible and contact profilometer is not correct any more.The Hartmann test has an advantage in that it has a larger dynamic range than interferometer.It means that the mirror can be tested with a Hartmann wavefront sensor without null compensator,so a new method using Shack-Hartmann wavefront sensor to nonnull test off-axis aspheric surface on axis is presented.Using a simulation reference file,testing an off-axis aspheric reflection mirror is carried out.This mirror is also tested by using contact profilometer and interferometer.Comparing the three testing results,the Shack-Hartmann testing is not only more accuracy than profilometer testing,but also larger dynamic range than interferometer testing.It also shows that the theory of testing system and separation of errors are correct.