Optical radiation damage of SBN materials and pyroelectric detectors at 10.6 μm

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Abstract
Thermal damage of Sr1−xBaxNb2O6 (SBN) crystals and infrared pyroelectric detectors due to 10.6−μm CO2 laser radiation was investigated. Permanent damage in the form of cracking or charring was observed depending on the irradiation conditions. Threshold values of energy density for cracking and charring were determined for SBN crystals of typical detector dimensions as a function of irradiation time. These damage thresholds of SBN are about an order of magnitude larger than the corresponding thresholds previously measured in triglycine sulfate. The energy density thresholds for cracking are independent of irradiation time τ for short times and increase as τ for long times. The time dependence of the cracking thresholds under the particular experimental conditions investigated is described by the empirical equation E0=[3+2400τ/tan−1(82τ)1/2] J/cm2. The charring thresholds are given by the empirical equation E0= (8+470τ1/2) J/cm2. The theoretical models presented for thermally induced damage are in satisfactory agreement with the experimental data. The damage thresholds of commerical SBN pyroelectric detectors were measured and found to correspond to those for SBN crystals.