Acoustic detection of damage to optical components by radiation from a pulsed TEA CO2 laser

An investigation was made of the feasibility of acoustic detection of the damage caused by pulsed radiation from a TEA CO₂ laser to infrared optical materials (CaF₂, BaF₂, ZnSe). The detector was a wide-band highly sensitive WAT-11 transducer made of lithium niobate. The state of the surface and of the interior of the test samples was examined with a microscope before and after irradiation. The magnification was a factor of 120. The dependences of the acoustic signal amplitude on the energy density of the laser radiation were determined. The earliest stages of the appearance of damage were accompanied by a strong (a factor of up to 10²) increase in the acoustic signal. It was concluded that a piezoelectric transducer made of lithium niobate is a promising device for the effective detection of laser damage to infrared optical components during the initial stages of the damage process.