Matsushita Electric Industrial Co., Ltd.

Kouji Handa

Keishi Kubo

Keiichi Yoshizumi

Hiroyuki Takeuchi

Yukio Imada

Arranged on both sides of a thin plate are optical displacement gauges that irradiate measurement lights onto surfaces of the thin plate and receive the measurement lights reflected by the surface so as to measure displacements of the surfaces of the thin plate. Variation of thickness of the thin plate is obtained on the basis of the displacements of the surfaces of the thin plate measured by each of the optical displacement gauges. Each of the optical displacement gauges detects the displacement of a respective surface of the thin plate with high accuracy by irradiating the measurement light to the thin plate two times.

Configuration measuring apparatus and method

The invention measures a thickness variation at a high accuracy around a wide range of a thin plate by a comparatively large spot diameter between 0.5 mm and 2 mm. A polarization beam splitter separating a laser beam emitted from a laser generator and transmitting through an isolator into a measurement light and a reference light is provided. A quarter wavelength plate is provided between the polarization beam splitter and a measurement surface, and between the polarization beam splitter and a reference surface. A focusing and reflecting means for focusing and reflecting the measurement light reflected by the measurement surface and reflected by the polarization beam splitter, and the reference light reflecting by the reference surface and transmitting through the polarization beam splitter is provided. A half mirror reflecting the measurement light and the reference light which return from the polarization beam splitter is provided. A light receiving portion receiving the measurement light and the reference light which are reflected by the half mirror so as to interfere, converting an interference light intensity change into an electric signal, and counting the electric signal so as to measure a flatness of the measurement surface is provided.

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Osaka, Japan

Kouji Handa