Wavefront measurement of membrane diffractive lens using line structured light deflectometry

In this paper, a wavefront testing method of membrane diffractive lens based on line structured light deflectormetry is proposed. The test membrane diffractive lens was placed between a screen and a camera, and a series of artificially coded line structured light that scanned on the screen were shot by the camera through the diffraction of the test lens. After the difference calculation of coordinates where light on the test lens and the screen, wavefront of the test diffraction order could be obtained by the integral of slopes. To improve the measuring accuracy, systematic errors were removed by N-step averaging method. In the experiment, a membrane diffractive lens with a diameter of 80mm, F/4.5 was measured using this method, which proved the feasibility after self-consistent results were obtained.