DETERMINATION OF THE LASER-INDUCED DAMAGE THRESHOLD OF BULK POLYMER SAMPLES AT 1.06-MU-M USING THE PULSED PHOTOTHERMAL DEFLECTION TECHNIQUE

A pulsed Nd-YAG laser beam is used to produce a transient refractive i ndex gradient in air adjoining the plane surface of the sample materia l. This refractive index gradient is probed by a continuous He-Ne lase r beam propagating parallel to the sample surface. The observed deflec tion signals produced by the probe beam exhibit drastic variations whe n the pump laser energy density crosses the damage threshold for the s ample. The measurements are used to estimate the damage threshold for a few polymer samples. The present values are found to be in good agre ement with those determined by other methods.