异形口径离轴非球面光学加工与测试技术

Fabrication and testing of an off-axis aspheric surface with abnormal shape

针对离轴非球面制造的难点,研究分析了碳化硅非球面尤其是异形离轴非球面加工和检测的各项关键技术。首先利用加工中心DMG对离轴非球面进行了铣磨和表面成形,然后运用实验室自行研制的非球面加工中心FSGJ-2对离轴非球面进行了研磨和抛光,最后利用离子束对其进行了精抛光,并分别利用三坐标测量仪和激光跟踪仪对非球面进行面形轮廓测定和光学参数及几何量的精确控制。结合工程实践对一口径为600mm×270mm的类八角形离轴碳化硅非球面反射镜进行了超精加工与检测,并专门设计研制了光学补偿检测装置,对其进行了零位补偿干涉测量,其最终面形PV值为0.219λ,RMS值为0.018λ。

In order to overcome the difficulty of manufacturing off-axis aspheric surface, the key technologies of fabricating and testing SiC aspheric mirror especially for off-axis asphere with abnormal shape were studied. The off-axis SiC aspheric surface was grinded and polished by DMG, FSGJ-2 numerical control machine and IBF, the contour and optical parameters were measured and controlled by the coordinate measuring machine and laser tracker. Finally, an example for fabricating and measuring a similar eight-square off-axis aspheric mirror with the aperture of 600 mm ×270 mm was given. For the purpose of testing the aspheric mirror by interferometry, a null lens compensator was specifically designed and developed. As results, the peak-to-valley （PV） and root mean square （RMS） values of the surface error are 0.219 and 0.018 （is 632.8 nm）, respectively.