SUPPRESSION OF SPECKLE CONTRAST BY USING POLARIZATION PROPERTY ON 2ND-HARMONIC GENERATION

A simple method to reduce the contrast of speckle structures of a rand om phase plate (RPP) using a harmonic conversion arrayed crystal in la ser fusion is presented. A specially fabricated four-segmented arrayed KDP (potassium dihydrogen phosphate) cell is introduced. The KDP crys tals in this cell were arranged to provide two groups of second harmon ic light beams whose polarizations are orthogonal to each other. A red uction of the speckle contrast of 20% has been obtained in a 320 mm di ameter beam of the Gekko XII laser system.