Measurement of focal length of lens using phase shifting Lau phase interferometry

In this paper, we proposed a phase shifting Lau phase interferometry for the measurement of the focal length of a lens. The fundamentals of this application are discussed and the basis of the phase map interpretation is outlined. A three step phase-shifting algorithm is used to depict the phase maps of a lens-like test object and an application for measuring the focal length of a lens is reported. A phase map obtained with a coherent light source is also shown and the merits of using incoherent light over coherent light source are also discussed. Experimental results are presented.