Simultaneous measurement of optical inhomogeneity and thickness variation by using dual-wavelength phase-shifting photorefractive holographic interferometry

•A method to measure thickness variation and optical inhomogeneity simultaneously is proposed.•A dual-wavelength phase-shifting photorefractive holographic interferometer is used.•Special requirements and additional operations on surfaces are not needed.•The wavefront distortion caused by the interferometer system can be compensated automatically.

A method to measure thickness variation and optical inhomogeneity simultaneously with a dual-wavelength phase-shifting photorefractive holographic interferometer is proposed. This method has no special requirements on the sample surfaces, and additional operations such as coating refractive index matching liquid on surfaces is not needed. With the help of photorefractive holographic interferometry, the wavefront distortion caused by the interferometer system is compensated automatically. Compared with other methods, this method is simpler and more accurate. Computer simulation and optical experiment have verified its feasibility and reliability.