New method to improve the accuracy in a sequential lateral shearing interferometer

© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). We present a new technique for measuring ultraprecise absolute optical surfaces. The technique combines the lateral shearing method but using a Fizeau interferometer. It achieves faster reconstructions than with a deflectometric system and without the influence of the reference surface. The system is limited by the imprecision of the linear stage and those of the estimation of the curvature of the reference surface. Regarding the guidance errors, we propose a new method to estimate pitch and roll based on data redundancy analysis. Numerical simulation results of pitch-and-roll estimations are given for realistic errors. Reconstructions using the sequential lateral shearing are also provided achieving nanometer accuracy.