Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1980-07-22
1983-12-20
Punter, William H.
Optics: measuring and testing
By polarized light examination
With light attenuation
356237, 356394, G01B 1100, G01B 1124
Patent
active
044214103
ABSTRACT:
In order to optically inspect wiring patterns on a printed wiring board, laterally travelling light rays are passed through a half reflecting mirror disposed above the printed wiring board so as to be directed downwardly, thereby illuminating a wiring surface of the printed wiring board with the light normal thereto and at the same time light is directed at a large incident angle to the wiring surface through, for example, optical glass fibers to illuminate the wiring surface, whereby a corner which is a part of the wall defining a plated through hole formed in the printed wiring board can be detected as an accurate optical image, thus ensuring a highly accurate inspection of the wiring patterns.
REFERENCES:
patent: 3782834 (1974-01-01), Fujimori et al.
patent: 3806252 (1974-04-01), Harris et al.
patent: 4277175 (1981-07-01), Karasaki et al.
Habegger, M. A., "Optical Determination of Semiconductor Device Profiles", SPIE vol. 80, Developments in Semiconductor Microlithography, 1976, pp. 95-99.
Habegger, M. A., "Optical Determination of Semiconductor Device Edge Profiles", IBM Tech. Disc. Bull. vol. 19, #2, 7/1976, pp. 474-477.
Hitachi , Ltd.
Punter William H.
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