1kHz 3.3[mu]m Nd:YAG KTiOAsO sub(4) optical parametric oscillator system for laser ultrasound excitation of carbon-fiber-reinforced plastics

We present a new laser prototype for laser ultrasonics excitation. The fundamental wavelength of a Q-switched Nd:YAG laser with a repetition rate of 1 kHz is converted to 3.3 [mu]m with a KTiOAsO sub(4) optical parametric oscillator. The achieved pulse energy at 3.3 [mu]m is 1.7 mJ, and the pulse duration at the fundamental wavelength of 1.06 [mu]m has been measured to be 21 ns. The ultrasonic excitation efficiency is about 3.5 times better compared to the application of state-of-the-art CO sub(2) lasers.