It is important for testing the process of crystal growing and crystal quality. This paper built a mathematical model based on principle of photothermal common-path interferometry, the index change induced in the crystal by the heating pump beam and the phase distortion of probe beam in the heated area are presented，then obtain the intensity distribution of the interference in the near filed. Optical geometry of focusing pump beam and intersecting pump and probe beams at waist position of the pump beam is used. This optical instruction can be adjusted easily and stabilized. Now CRYSTECH have the largest NLO crystals product line in the world, especially KTP crystals. With absorption measurements in nonlinear laser crystal KTP as an example to investigate the experimental parameters affecting the photothermal interference signal and high measuring precision. The analysis of experimental data showed this kind of instruction can reach the measurement accuracy of 0.1ppm.

Date Published: 9 July 2013
PDF: 6 pages
Proc. SPIE 8786, Pacific Rim Laser Damage 2013: Optical Materials for High Power Lasers, 87861R (9 July 2013); doi: 10.1117/12.2019741

Published in SPIE Proceedings Vol. 8786:
Pacific Rim Laser Damage 2013: Optical Materials for High Power Lasers
Jianda Shao; Takahisa Jitsuno; Wolfgang Rudolph, Editor(s)