The unambiguous distance measurement range in two-color interferometry is generally understood to be limited to the equivalent or synthetic wavelength, which is inversely proportional to the wavelength separation of the two colors. Here it is shown that one may extend the unambiguous range well beyond this limit by using optical phase information to determine the synthetic-wavelength fringe order.
© 1994 Optical Society of America
Peter J. de Groot, "Extending the unambiguous range of two-color interferometers," Appl. Opt. 33, 5948-5953 (1994)