Optics: measuring and testing – By configuration comparison – With photosensitive film or plate
Patent
1985-04-15
1987-05-19
LaRoche, Eugene R.
Optics: measuring and testing
By configuration comparison
With photosensitive film or plate
250578, G01B 1106
Patent
active
046663053
ABSTRACT:
An improved film thickness measuring apparatus including an optical measuring system, a detective photomultiplier tube, a corrective photomultiplier tube, a control circuit and a signal processing section. Measuring of the film thickness of a sample material is carried out with the use of spectral reflectivity while optical interference takes place between light beam coming from the surface of the layer structure of the material and light beam coming from the base plate constituting the sample stage. Light beam from light source is introduced into a monochromator to spectrally transform it to monochromatic light. The optical measuring system includes a chopper which serves to chop light beam fed from the light source to introduce intermittent light beam into the monochromator. The latter is provided with a rotatable diffraction grating to effect scanning of wavelength. The second optical system includes a detective semi-transparent mirror, a corrective semi-transparent mirror and an objectve lens so that a part of monochromatic light beam is introduced into the detective photomultiplier tube via the detective semi-transparent mirror. A screen for the optical projection system is provided on the front surface of the housing section to visually observe an image of the sample material in an enlarged scale.
REFERENCES:
patent: 3664743 (1969-11-01), Kanda
patent: 3827811 (1974-08-01), Kato et al.
patent: 3869211 (1975-03-01), Watanabe et al.
patent: 3879135 (1975-04-01), Egli et al.
patent: 4355903 (1982-10-01), Sandercock
Mochida Yoshihiro
Shirahama Ichiro
LaRoche Eugene R.
Lee James C.
ORC Manufacturing Co. Ltd.
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