Masahide ITOH, Ryuji YAMADA, Ronglong TIAN, Minghong TSAI and Toyohiko YATAGAI

Institute of Applied Physics, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba, Ibaraki, 305 Japan

(Accepted January 18, 1995)

The absolute longitudinal distance between two points can be determined by the corresponding correlation peaks of two light-waves from a broad-band light source. Using this technique, the height of three-dimensional objects can be measured without 2Ež phase ambiguity. We can also detect the absolute position of scattering seeds in sub-surface or bulk materials such as defects, dislocations or impurities of high purity materials. The wavelet analysis is used to determine the correlation peaks. This technique can be applied to measurement of thickness of a few hundred microns.

Key words : interferometry, correlation, broad-band spectrum, wavelet analysis