Three dimensional photothemal microscopy of KDP crystals

摘要

The laser damage threshold of KDP crystals is one major limitation in many high-power laser systems. Investigation of laser damage behavior of KDP crystals shows that the major reason for the laser damage is due to growth defects in the bulk of the crystals. Therefore, an effective diagnostic method for those defects is quite necessary for producing KDP crystals with high enough damage threshold to meet the requirement of high power laser applications. In this paper, we reported characterization of bulk defects in KDP crystals using a three dimensional photothermal microscope based on a laser-induced photothermal lensing technique. Several 3D images of the bulk defects were obtained. The results indicated that both surface defects and bulk defects can be determined and analyzed using the 3-D photothermal microscope. Details of development of the 3-D photothermal microscope were also presented. The system provided user-friendly operations of the defects characterization process and showed great potential of application for characterization of low absorption optical materials.