Talbot interferometry is used to study the surface profile of a transparent object. Periodic patterns are produced by illuminating a grating with a collimated laser beam. The object is placed on the self-image plane of the grating. The deformed grating image, which interferes with another grating, results in the Talbot interferometric fringes. The fringe pattern is recorded on a CCD camera for subsequent analysis, and the phase variation is achieved by a linear translation stage. In this application two specimens are tested to demonstrate the validity of the method; one is a transparent object with a spherical shape with a height of less than 350 µm, and the other is a transparent object with an uneven surface of 50-µm average height. The experimental results are compared with the test results obtained with the mechanical stylus method.
© 2005 Optical Society of America
(050.2770) Diffraction and gratings : Gratings
(050.5080) Diffraction and gratings : Phase shift
(070.6760) Fourier optics and signal processing : Talbot and self-imaging effects
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
Madhuri Thakur, Cho Jui Tay, and Chenggen Quan, "Surface profiling of a transparent object by use of phase-shifting Talbot interferometry," Appl. Opt. 44, 2541-2545 (2005)