Inspection of mechanical surfaces with polarized structured light

Measuring scratches, nicks and dents on precision machine parts is a challenge for industry, especially when the parts have to be tested on the factory floor or in the field, far from any metrology laboratory. A new system that combines dynamic interferometry with structured light enables the projection and analysis of polarization-based virtual fringes in a single camera frame. This very compact system, the metrology setup is flashlight-sized, is capable of micrometer precision, yet is immune to vibration, which enables handheld operation in a variety of environments. This paper will discuss the technical approach to achieve vibration-immune 3D measurements and will present a variety of performance tests and a discussion of practical applications of the system.