Abstract

Until now there has not been an accurate method for measuring the radius of curvature of a short-pulse or broad-band laser. This is because the standard shearing plate interferometer¹ used to measure the radius of curvature of a beam cannot be used for beams with coherence times shorter than 70 ps. The adjustable, lateral shearing, cyclic shearing interferometer (CSI) solves this problem. The CSI produces a fringe pattern as does a standard shearing plate collimation tester, except that the CSI can be used on beams with coherence times Δt_c as short as one picosecond, since the two beams in the interferometer follow nearly the same path. The CSI is easy to align, and the radius of curvature of the incident light beam can easily be computed once the distance between the fringes and the fringe's angle with respect to the horizontal is known. Comparison with data from a broad-band, XeCl laser (Δt_c ~ 30 ps) confirms that the CSI performs as theory predicts.

© 1990 Optical Society of America