IMPROVED PHASE-SHIFTING METHOD FOR AUTOMATIC PROCESSING OF MOIRE DEFLECTOGRAMS

An improved moire deflectometry phase-shifting technique is presented. A squared grating is used to multiplex the information of the deflect ions in two orthogonal directions in one image. This procedure avoids the need to rotate the gratings to obtain complete deflection informat ion. However, the use of these gratings makes impossible the applicati on of standard phase-shifting algorithms. Specifically, the problems a ssociated with the nonsinusoidal profile of the moire fringes and the low-modulation areas produced by the square gratings are solved. A mod ified moire deflectometry phase-shifting method is designed to deal wi th these problems. In addition, a method to obtain the zero order of t he prismatic effect is developed. The technique configures a complete and automatic method of mapping ray deflections. From them the refract ive power maps can be derived. Experimental results obtained with a pr ogressive-addition lens are shown. (C) 1998 Optical Society of America