磷酸二氢钾晶体超精密加工存在的若干问题分析

An Analysis on Some Problems in Ultra-precision Machining of Potassium Dihydrogen Phosphate Crystals

磷酸二氢钾(KDP)晶体作为优质的非线性光学材料,在现代光学领域应用越来越广泛,常用作光学频率转换器件和电光开关元件。KDP晶体具有质软、脆性高和易潮解等不利于光学加工的特点。在国家点火装置(NIF)的研究中,经常采用单点金刚石切削(SPDT)加工KDP晶体以获得超光滑表面。采用单点金刚石切削加工具有强烈各向异性KDP晶体时,选用的背吃刀量和进给量非常小,这时发现切削行为、微切削力的波动和近表层力学性能都随晶体的切削方向的变化而变化。但到目前为止,在文献中很难找到一些关于KDP晶体超精密加工方面的有价值参考数据。着重介绍KDP晶体超精密加工技术的近期发展状况,详细分析KDP晶体超精密加工中存在的若干问题。

Potassium Dihydrogen Phosphate （KDP） has been found more and more important applications in the field of modern optics. KDP crystal is a non-linear optical material used for laser frequency conversion, it has several weak points, such as soft, brittle and deliquescent from the machining point of view. In the National Ignition Facility （NIF） research program, KDP crystal has been studied on single point diamond turning （SPDT） for getting optical surfaces. In diamond turning of highly anisotropic materials like KDP crystals, the depth of cut and feed is very small, the cutting behaviour, the variation of micro-cutting forces and the near-surface mechanical properties have been found to vary with the crystallographic cutting direction. However, up to now, it is hard to find some useful data on ultra-precision machining of KDP crystals. In this paper, the latest development is generally reviewed, and some problems existing in ultra-precision machining of KDP crystal have been analyzed in detail.