Abstract

The Lau interferometer uses an incoherently illuminated grating to produce a periodic coherence function which illuminates a phase object. A second grating following the phase object causes multiple sheared images that are coherent with respect to each other. If the first grating is imaged onto the second grating the shearing is wavelength independent, so a broadband incoherent source (for example, a tungsten lamp) may be used as a source. Bias fringes may be introduced by defocusing the gratings with respect to each other. The introduction of bias fringes also makes the interferometer sensitive to the position of the phase disturbance between the two gratings. Interference patterns are formed for only a thin section within a thick phase disturbance.

© 1985 Optical Society of America