Measuring the thickness of metal sheets is an issue of great importance in production facilities and in other industrial applications. The conventional triangulation method is not suitable for the detection of rough surfaces and semitransparent or multi- scattering materials. Therefore, an adaptive two- wave mixing interferometer based on the photorefractive Bi12SiO20 (BSO) crystal is designed to measure the thickness of an aluminum metal sheet. A holographic grating, formed by the photorefractive effect, diffracts both the signal beam and the reference beam to demodulate the ultrasonic vibration. The system, in which the low frequency noise caused by the environmental perturbation can be filtered automatically through the dynamic holography grating, is demonstrated to be a highly sensitive, convenient, and inexpensive non- contact technique for thickness measurement and ultrasonic vibration detection on rough surfaces. The technique has the potential for the detection of hidden defects, especially when it is combined with laser ultrasonic technology.