应用离子束修正高精度CGH基底

计算全息图(CGH)作为零位补偿器广泛应用于高精度非球面的检测中,但CGH的基底误差直接限制了非球面的检测精度。为了获得超高精度的CGH基底,提出了应用离子束修正CGH基底的加工工艺。采用不同束径的离子束去除函数对一边长152 mm(有效口径140 mm圆形区域)、厚6.35 mm的正方形熔石英CGH基底分别进行了精抛、精修和透射波前修正实验。经过总计7轮的迭代修正,最终获得了透射波前为PV值20.779 nm、RMS值0.685 nm的超高精度CGH基底。实验结果表明:应用离子束修正高精度CGH基底的加工工艺具有较大优势,不仅具有较高的加工效率而且可以获得超高的加工精度。

High-precision CGH substrate figuring by ion beam

Computer-generated hologram(CGH) is widely applied in the high-precision testing of asphere as high-accuracy null compensator, but the surface figure error of CGH substrate directly restricts the testing precision. In order to gain ultra-precision CGH substrates, the figuring of high-precision CGH substrates by ion beam is presented. A square fused silicon CGH substrate with 152 mm side length(140 mm valid aperture) and 6.35 mm thickness is figured by different scale IBF removal functions. Through seven iterations, an ultra-precision CGH substrate with transmitted wavefront PV value 20.779 nm and RMS value 0.685 nm is gained finally. The experiment result shows that figuring high-precision CGH substrates by ion beam has notable advantage, and it has not only high process efficiency but also ultra-high process precision.