SHAPE MEASURING APPARATUS AND METHOD

摘要

PROBLEM TO BE SOLVED: To facilitate measuring thickness variation in a thin plate member such as a wefer accurately and efficiently. SOLUTION: The beam diameter of light gathered with a lens 1 is focused to ca. 0.1 mm by passing it in a polarization beam splitter 2 and irradiating the thin plate member 4 twice with measuring light, and the distortion of light signal is reduced to 1/2 by placing a lens 5 on a different surface of the polarization beam splitter 2.