Ф420mm高次非球面透镜的加工与检测

Fabricating and testing of Ф420mm high-order aspheric lens

介绍了Ф420mm熔石英高次非球面透镜的加工与检测方法。对现有数控加工工艺进行了优化,通过分工序加工方式,依次采用机器人研磨、抛光和离子束修形技术完成了透镜的加工。进行非球面透镜检测时,考虑透镜的凹面为球面,利用球面波干涉仪对其面形进行了直接检测,剔除干涉仪标准镜镜头参考面误差后,透镜凹面的精度达到0.011λ-RMS;针对透镜的凸面为高次非球面,采用基于背后反射自准法的零位补偿技术对其进行面形检测,其精度达到0.013λ-RMS。最后,采用一块高精度标准球面镜对加工后透镜的透射波前进行了自消球差检测,得到其波前误差为0.013λ-RMS。试验结果表明,非球面透镜各项技术指标均满足设计要求。所述工艺方法亦适用于更大口径的非球面透镜及其他类型非球面光学元件的高精度加工.

The fabrication and testing of a Ф420 mm fused silica high-order aspheric lens were presen- ted. Current fabricating technologies were optimized, and robot grinding, polishing, and ion beam figuring were respectively applied to the fabrication of lens. For testing an aspheric lens, a spherical interferometer was used to test the concave surface of spheric lens, and the result shows that the test accuracy is 0. 011λ-rms after the error of interferometer standard lens reference surface was removed. Furthermore, null compensators based on reflective auto-collimating method were taken to test the high-order convex aspherical surface,and the surface figure errors are 0. 013λ-rms. Finally, a standard spherical mirror was used to test the transmission wavefront of processed aspheric lens with self-apla- natic form,and the transmission wavefront errors of aspheric lens is 0. 013λ-rms. The testing results indicate that the entire specifications meet the requirements of design. The processing methods pro- posed by the paper are suitable for the fabrication of larger aspheric lenses and other larger aperture aspherical elements.