Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1982-08-23
1985-05-07
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356 4, 350 68, H01J 314, G01C 308
Patent
active
045160244
ABSTRACT:
In an optical scanning system suitable for use in an aircraft for ground contour measurements, wherein the received image from an illuminated ground spot is reflected from a rotating prism onto paraboloidal mirrors which focus the image at a common focal point, and wherein the rotating prism is also used to transmit the scanning spot-illuminating beam, a wedge-shaped light guide accepts the coincident focused images and funnels them into a photoelectric detector. Because the prism rotates at high speed, variations in light signal transit times due to differences in target distance over the range of the scan cycle and due to differences in aircraft altitude cause the image focal point to shift, necessitating a relatively wide rectangular input aperture on the light guide, resulting in the admittance of large amounts of background light in to the detector. An adjustable shutter is positioned immediately in front of the light guide input aperture to effectively limit the size of the aperture and thereby reduce the background light interference. Shutter baffles which move in response to aircraft altitude are mechanically coupled such that they provide an aperture opening just sufficient to admit the range of image focal points for that altitude.
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Brophy J.
Maginniss Christopher Lyle
Nelms David C.
RCA Corporation
Tripoli Joseph S.
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