针对热弯玻璃成形法制备高精度超薄反射镜时Pt分离膜造成的镜片污染问题,研究了Pt/Cr分离膜中不同Cr层厚度对热成形超薄反射镜玻璃基底表面粗糙度的影响.采用厚度为0.3 mm的Schott D263玻璃作为超薄反射镜基底材料,选取Pt、Pt/Cr作为模具和D263镜片之间的分离层材料进行实验.Pt薄膜的厚度为50 nm,Cr层厚度分别为5 nm、3.5 nm、2.5 nm、1.5 nm,热成形实验采用“直接”复制方式.实验结果表明:Cr层厚度为1.5 nm时,成形后模具表面分离膜未发生脱落,镜片表面粗糙度约为0.5 nm,与D263镜片初始值接近,能够满足高能X射线望远镜对反射镜基底表面粗糙度的要求.

In order to solve the lens pollution problem caused by Pt release layer in the preparing process of high quality thin mirrors with hot slumping glass technology,the effect of Cr layer thickness on surface roughness of thermal formed glass substrates by using "direct" slumping method was studied.The Schott D263T glass sheets with thickness of 0.3 mm were used as raw materials of ultra thin mirror substrates,and Pt,Pt/Cr layer were selected as release medium between the mould and D263 glass foils.Fixed coating thickness of the Pt layer was 50 nm,and thicknesses of Cr interlayer were 5 nm,3.5 nm,2.5 nm,1.5 nm,respectively.The results show that,after thermal forming treatment,when the thickness of Cr layer is 1.5nm,release layer does not peel off from the mould and the roughness of glass sheet is about 0.5 nm,which is close to the initial testing value of raw D263 glass and could meet the surface roughness requirement of substrates used for hard X-ray telescope.