Research On Polishing Technology For KDP Crystals Based On Deliquescent Action

KDP (Potassium Dihydrogen Phosphate) crystal is a kind of good electro-optic nonlinear optical material developed in 1940s. In solid-state lasers for Inertial Confinement Fusion(ICF) and high power laser weapons, it is an irreplaceable material for the application in optical frequency converters and electro-optic switches. But the KDP crystal is soft, fragile, deliquescent and sensitive to temperature change, which is very disadvantageous to its machining. At the same time, in ICF, high demands are made on the optical elements of KDP crystal. All of these make it difficult to machine KDP crystal, optical parts with large sizes and high precision made of it is known as one kind of the optics most difficult to fabricate. Presently, the ultraprecision machining methods applied to KDP crystals have some defects, they still remain to be further improved. In order to meet the requirements of practical applications, on the one hand, the existing ultraprecision machining methods applied to KDP crystals should be improved, on the other hand, new ultraprecision machining technologies for KDP crystals should be searched after.To meet the requirement of the developing in ultraprecision machining technologies for KDP crystals, this dissertation proposes a new technology, i.e. polishing technology for KDP crystals based on deliquescent action, which utilizes deliquescent action for ultraprecision machining KDP crystals. The key technologies of this method are studied in the dissertation. The main aspects of the study are including:First the general status of the ultraprecision machining methods applied to KDP crystals in both domestic and overseas is reviewed, and some novel polishing technologies are briely introduced. On the basis of the review and the introduction, according to the characteristic that KDP crystal is deliquescent, the polishing technology for KDP crystals based on deliquescent action is proposed.Based on the introduction of KDP crystal and the researching of essence of deliquescence, the dissolution experiment of KDP crystal's surface was conducted, and referring to the material removal mechanism in chemical mechanical polishing wafer, the material removal mechanism in polishing of KDP crystals based on deliquescent action is proposed. The polishing process of KDP crystals based on deliquescent action was planned, the polishing experiment of KDP crystal based on deliquescent action was carried out, the validity, feasibility and effectiveness of the material removal mechanism was verified.On the basis of analyzing the polishing process of KDP crystals based on deliquescent action simply, the significance of controlling the deliquescent action in polishing of KDP crystals based on deliquescent action is discussed, the ieda of controlling the deliquescent action of water through polishing fluid with water is proposed. The polishing fluid is studied with emphasis. The polishing fluid was developed. Through polishing experiments of KDP crystals based on deliquescent action, the controlling method of deliquescent action was verified, and the performance of the developed polishing fluid was tested.Through polishing experiments of KDP crystals based on deliquescent action, effect of main input variables, including KDP crystal's initial surface state, polishing time, revolution of polishing plate, etc., on material removal and surface roughness in polishing of KDP crystals based on deliquescent action is stuedied. The processing parameters combination is achieved to get better polishing results in polishing of KDP crystals based on deliquescent action. The study will be the basis for the further researching and application of the polishing technology for KDP crystals based on deliquescent action.To the polishing process of KDP crystal based on deliquescent action, kinematic analysis is made. On the basis of the analysis, track, velocity and polishing distance of a point on the KDP crystal's surface in polishing of KDP crystal based on deliquescent action are studied. The polishing process of KDP crystal based on deliquescent action is analyzed theoretically, and the effect of main parameters in polishing on polishing process is studied.