Analysis of damage threshold on HgCdTe crystal irradiated by multi-pulsed CO2 laser

• We measure damage threshold of HgCdTe irradiated by multi-pulsed CO2 laser.
• The impact of repetition frequency and time on damage threshold is analyzed.
• Damage morphology of the crystal is observed and analyzed by SEM.
• Three-dimensional physical model is used to approve the experimental conclusions.

Damage threshold for the onset of surface melting was investigated theoretically and experimentally on HgCdTe crystal irradiated by multi-pulsed CO2 laser. The impact of repetition frequency and irradiation time on damage threshold was analyzed and damage morphology of the crystal was observed by scanning electron microscope (SEM). Thermal accumulate effect is obvious, and damage threshold gradually reduces with the increase of irradiation time and does not depend on laser repetition frequency. Damage threshold calculated by thermal model is in good agreement with the experimental data. Melting and solidification phenomenon were evident on the crystal surface, and the obvious crack which was caused by thermal stress was not found. Theoretical model gives a reasonable explanation on surface morphology changes.