Theoretical And Experimental Study On The Optimum Cutting Direction Of KDP Crystal

As optics frequency multiplication translation unit and electro-optic switch, because of the high nonlinear and laser damage threshold value, The Potassium dihydrogen phosphate (KDP) crystals is used in optics system in ICF high power solid laser. High accuracy KDP crystal optics is now considered as one of optics that is the most difficult to be processed for its series of disadvantageous characteristics to optics processing such as anisotropy,soft nature,easy to deliquesce,high brittleness,sensitive to temperature change,easy to crack and so on,it cause the long machining period, low percent of pass and astaticism quality. So the most important problem need to solve is finding the best cut orientation, and get high degree of accuracy of finished surface by researching machining mechanism, mechanical character and so on.This article starting from the crystal structure, first researched on KDP crystal mechanics characteristics in different crystal plane and orientation through theoretical analysis and nano-indentation experiment, separately calculated the Young's modules and shear modules of KDP in different crystal plane, and systematically analyzed the change rule of Young's modules and rigidity along with the crystal orientation. The analysis result indicates that, KDP crystal mechanics characteristics, such as Young's modules, shear modules, rigidity and so on, have intense anisotropy is the important factor affecting processing surface quality. A theoretic model of shear angle of KDP ultra-precision machining is built with the principle of the maximum specific energy of shear deformation and the mechanism of change of the shear modulus with different crystal planes and orientations. This article analyses the effect regular from friction angle's aeolotropism to shear angle by friction experiment, and measuring friction coefficient in different orientation with a theoretic model of shear angle of KDP. Extract the best cutting orientation is the most in critical brittle-ductile transition depth by cutting on different depth of scratch experiment, and researching the different between the critical cutting depths in different orientation. As crystal face (001) example, this article researches the influence of anisotropy of KDP crystal and cutting force by cutting experiment. The theory...