High-speed measurement of three-dimensional surface profiles up to 10 mu m using two-wavelength phase-shifting interferometry utilizing an injection locking technique

Abstract

High-speed two-wavelength phase-shifting interferometry is presented. The technique is aimed at highspeed in-line inspection of spacers in liquid crystal display panels or wafer bumps where the measuring range is well determined and high-speed measurements are essential. With our test setup, the measuring range is extended to 10 mu m by using two injection locked frequency scanning lasers that offer fast and equidistant phase shifting of interference fringes. A technique to determine the unwrapped phase map in a frequency scanning phase-shifting interferometry without the ordinary phase-unwrapping process is proposed. (C) 2011 Optical Society of America