Chuen-Lin TIEN^*, Siao-Shan JYU, and Huei-Min YANG

Institute of Electrical Engineering, Feng Chia University, Taichung, Taiwan 40724, R.O.C.

(Received August 31, 2008; Accepted February 3, 2009)

A new approach for fringe normalization by Zernike polynomial fitting to cancel background illumination in an interferogram is proposed. With this method, background illumination can be suppressed, high frequency noise is immunized and the contrast is improved by normalization. The main idea for this paper is to use the Zernike polynomial fitting interferogram to cancel background illumination; the high frequency noise is then filtered by a Wiener filter. Finally, the paper uses the method of local region contrast modulation to enhance fringe contrast. This method can overcome the problem of the non-uniformity illumination of fringe patterns resulting from the marginal reflection of optical components and a non-uniformity light source.

Key words: interferogram, fringe normalization, Zernike polynomial fitting, background illumination, fringe contrast

^*E-mail address: cltien@fcu.edu.tw