Referenced Polarization Imaging for surface displacement measurements

A Referenced Polarization Imaging (RPI) method can be used to measure surface displacements in an uncontrolled environment without the use of complicated feedback and stability controls. The system is ideal for non-contact and nondestructive testing of parts or materials. Data can be acquired in a single frame, so that the effects of vibration are minimal. High resolution wavefront sensing is performed using polarization modulation instead of frequency shifting (which is necessary in a heterodyne detection system). A system for recording complex (amplitude and phase) images of coherently illuminated objects is described. The promise for this type of system is the ability to obtain digital complex images at real-time rates with simple hardware. These images can be digitally interfered on a standard PG to measure changes in the object at real-time rates. A simple RPI system is described and experimental results demonstrating performance are presented.