Extended Depth from Focus Using White Light Interferometer

A new approach to 3-D profilometry for the white light interferometric (WLI) is presented. We detail a simple way to construct a profiler that uses the fringe contrast degradation of white light Mirau interferometer. The amount of fringe contrast degradation in the Mirau interferometer can be founded by depth from focus (DFF) method. In the method, the variance of the mismatch function and the modified local variance function are used as the focus measures. The proposed method is named as the extended depth from focus (EDFF) that determine the zero optical path difference (OPD) from the quantity of fringe contrast degradation of white light interferometer. The method has a theoretically unlimited range and can profile with subpixel accuracy both optically rough and smooth surfaces without changing algorithm.

• Type: Conference
• Year: 2000
• Where: ICIP
• Authors: Seok-moon Ryoo, Jae seon Kim, Tae-Sun Choi
• Keywords: Fringe Contrast Degradation, ICIP 2000, Image Processing, Light Mirau Interferometer, White Light Interferometer