Optical detection of ultrasonic wave presents several advantages over conventional acoustic technique.Two-wave mixing (TWM) technique has adaptive character which is suitable to demodulate ultrasonic waves with high frequency such as those generated by pulsed lasers or piezoelectric transducers.The aim of this work is to provide two types of adptive laser interferometer used to laser ultrasonic inspection and health structure monitoring.Principle of the interferometer is based on TWM in photorefractive crystals.Interferometric systems based on InP∶Fe crystal in the diffusion regime and drift regime were built and tested in the present work.TWM interferometer system includes a InP∶Fe crystal, continuous laser device at 1550 nm with a 20 mW, EDFA with amplification from sub-dBm and around 27 dBm, collimators, half-wave plates and photodetector.A PZT transducer is introduced to provide ultrasonic signals at various frequencies, and the two types of TWM interferometer systems are used to detect the ultrasonic waves.The performance characteristics of the TWM interferometer systems are evaluated in terms of adaptivity, frequency-response, and sensitivity.TWM interferometer is not sensitive to low frequency ambient vibrations and temperature change which makes it very attractive for industrial applications.