用计算全息法检测卡塞格林系统主镜

为实现对卡塞格林光学系统中的非球面主镜表面面形的高精度检测,设计了一种二元位相型计算全息图(CGH)。介绍了工作原理,对CGH的相位模型参数的优化设计、衍射次级分离以及台阶位置与深度计算等关键问题进行了讨论。通过引入虚拟玻璃的概念快速建立非球面检测模型,针对卡塞格林系统主镜中心开孔的特点,通过加入同轴载波实现了衍射次级的完全分离,相比目前常用的倾斜载波方法简化了相位量化复杂度,数值仿真计算出了最优的台阶深度,降低了加工难度。给出了相应的设计方法及实例,研制投产了CGH。测试得到主镜面形的均方根误差为0.018λ,并与传统补偿器结果(RMS=0.019λ)进行对比,两者测试结果吻合,验证了该设计与检测方法的正确性,该设计方法简单快捷,适用于卡塞格林光学系统主镜面形检测。

Surface Testing of Primary Mirror in Cassegrain Optics with Computer-generated Hologram

A binary phase computer-generated hologram(CGH)is designed for precisely testing an aspherical surface in Cassegrain optics.the design principle and is reviewed,Key questions about Optimal Designing of CGH phase function,calculation of Step position and depthare discussed.the concept of virtual glass is introduced for modelling tested surface quickly,the diffraction order is separated by joining coaxial carrier in allusion of center hole of primary mirror in cassegrain system,complexity of phase quantification is simplified,the optimal depth is gotten by numerical simulation,reducing the processing difficulty.design methods are proposed.an instance and simulation is presented and the CGH is produced.root-mean-square (RMS)error obtained from surface testing is 0.018λ,the test result is compared with that of compensatory mirror test meth,which is 0.019λ (RMS).It is demonstrated that the results show a good agreement.The design method is effective,can be used insurface testingof primary mirrorin Cassegrain optics.