Abstract: The digital speckle photographic technology combining with PC software for measuring thermal expansion coefficient is proposed. The project is feasible verified by experiments. By using the most scientific and reasonable method of least squares to process data,the optimal temperature- displacement curve is obtained. The experimental results compared with the Cu thermal expansion coefficient of recognized has 1. 2% error. In comparison with the traditional measurement methods,this approach improves accuracy and simplifies procedure. So it can be used to measure unknown thermal expansion coefficient.

Key words: thermal expansion coefficient, laser, digital speckle, correlation approach