Real-time holographic interferometry performed with two very thin, parallel, closely spaced object illumination beams can be used to produce a time-varying irradiance which, when incident on a photodetector, gives a signal whose analysis indicates both the normal displacement and tilt at a point on the object surface. The signal also contains information about in-plane translation which can be utilized in some cases.
© 1983 Optical Society of America
Youren Xu and Charles M. Vest, "Holographic technique for simultaneous measurement of displacement and tilt," Appl. Opt. 22, 2137-2140 (1983)