Novel magnetorheological figuring of KDP crystal

• 来源期刊: 中国光学快报（英文版）
• 年，卷（期）: 2011,（11）
• 页码范围: 71-75
• 页数: 5页
• 语种: 英文
• DOI: 10.3788/COL201109.102201

摘要

A new process of magnetorheological figuring (MRF) based on the deliquescence theory is proposed to finish KDP crystals.A novcl,non-aqueous,and abrasive-free magnetorheological (MR) fluid is explored,and polishing experiments are performed on a self-developed MRF machine.The removal mechanism is reckoned to be the result of a combination of dominant chemical etching and accessorial mechanical drag.The results indicate that the surface roughness of I plate KDP of 80 x 80 (mm) polished by MRF is 1.2 nm(root mean square (RMS)),and the tool marks are completely removed.The surface accuracy by MRF is 0.035λ (RMS),and the low/middle-frequency errors are significantly corrected after MRF.KDP is a significantly important nonlinear optical crystal.It is widcly used in solid state laser systems as frequency converter and electric-optical switch[1,2].At present,it is primarily considered as one of the most difficult optical materials to process due to its low hardness,high brittleness,high deliquescence,and extreme sensitivity to temperature changes[3,4].Currently,the most common and reasonable process for finishing KDP is single-point diamond turning (SPDT)[5-7].America Lawrence Livermore National Laboratory (LLNL)in America and Harbin Institute of Technology (HIT)in China have both developed ultra-precision flatness fly-cutting machines.KDP crystals machined by these equipment have been considerably applied in laser systems.