New technique of photodisplacement imaging using one laser for both excitation and detection

Abstract

A new interferometry technique has been developed that uses only a single laser for both exciting and detecting photothermal displacement, which greatly simplifies the system and the optical alignment. The minimum detectable displacement 10−2 Å/(Hz)1/2 is obtained. To examine this setup, we have performed a simulated experiment. And also, we have succeeded in imaging the subsurface flaw in a copper block. The preliminary results demonstrate that this new method is very promising for nondestructive evaluation and other applications.