Focal length and radius of curvature measurement using coherent gradient sensing and Fourier fringe analysis

A procedure for the measurement of focal length and radius of curvature of a lens using coherent gradient sensing system and Fourier transform fringe analysis technique has been demonstrated. Light from the laser illuminates the specimen and the wavefront emerging from the specimen is tested using coherent gradient sensing interferometer. The fringe pattern corresponding to the test wavefront is stored, and analyzed using Fourier fringe analysis technique. The slope of the wavefront in the direction of shear has been evaluated. It provides the information regarding exact location of points corresponding to the focus/center of curvature of the lens. High accuracy and precision has been achieved.