Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1985-03-21
1987-01-06
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356376, G01N 2186, G01B 1124
Patent
active
046348794
ABSTRACT:
Optical triangulation is used for determining the profile of a surface with only two photomultiplier tubes needed for optical sensing in a flying spot camera system. A feedback arrangement varies the angle at which a laser beam is applied to the surface such that the image of the beam on the surface tends to be maintained constant with respect to a linear reference position parallel to a scanning direction. Deviations in the image from its reference position as caused by surface height variations are used in the feedback arrangement to change the deflection angle. The deflection angle is in turn detected and is indicative of the variations in surface height. As an anti-noise feature, amplitude modulation is impressed upon the laser beam directed towards the surface and a filter network is used to filter photomultiplier response so as to exclude response to background optical noise. In order to maintain a very wide dynamic range, the modulation amplitude of the light applied to the surface is varied in inverse relationship to the intensity of reflected light sensed by the photomultipliers.
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Davis Jr. James C.
General Electric Company
Nelms David C.
Oen William L.
Webb, III Paul R.
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