Circular grating moiré deflectometry analysis by zeroth and first radial fringe order angle measurement

Abstract

The previous method of counting integer fringe orders in circular grating moiré deflectometry yields inaccurate measurements. One way to improve the measurement accuracy with this method is by lowering the grating pitch. The attendant higher cost and possible encroachment of the diffraction limit, however, restricts the practicality of this approach. An alternative analysis method, which measures the angle between the zeroth and first radial fringe order, is presented in this paper to overcome this problem.