Mid-infrared pulsed laser ultrasonic testing for carbon fiber reinforced plastics.

Laser ultrasonic testing (LUT) can realize contactless and instantaneous non-destructive testing, but its signal-to-noise ratio must be improved in order to measure carbon fiber reinforced plastics (CFRPs). We have developed a mid-infrared (mid-IR) laser source optimal for generating ultrasonic waves in CFRPs by using a wavelength conversion device based on an optical parametric oscillator. This paper reports a comparison of the ultrasonic generation behavior between the mid-IR laser and the Nd:YAG laser.

Temperature-controlled picosecond-pulsed high frequency second-harmonic generation by a periodically poled stoichiometric LiTaO(3).

We report experimental results of second-harmonic (SH) generation (SHG) by a quasi-phase-matched periodically poled Mg-doped stoichiometric LiTaO(3) crystal for 1030 nm input radiation of 18 ps pulse duration, within the range of peak input laser intensity I = 0.1-9.5 GW/cm(2) and under repetition rate 10-20 kHz.

Comparison of two-color hologram lifetimes of near-stoichiometric lithium niobate and of tantalate crystals.

Lifetimes of two-color nonvolatile holograms recorded in undoped or in slightly doped near-stoichiometric lithium niobate and tantalate crystals were measured and compared by extrapolation of the high-temperature data. A proton-compensation mechanism dominated the dark decay and yielded similar activation energies, of 1.05 and 1.