Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1980-12-23
1982-12-14
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250548, G01B 1106
Patent
active
043639623
ABSTRACT:
A optical focussing apparatus, preferably used in the manufacture of integrated semiconductor circuits which automatically positions the focal point of a lens on an object to be focussed on. The focussing apparatus is comprised of a plurality of optical sets distributed around the object, each of which sets is comprised of a photo emitter for projecting a light beam onto the object and an oppositely disposed photo detector for receiving the light beam reflected from the object. Means are provided to adjust the relative distance between the object and the focal point of the lens in response to the average intensity level of the reflected light beams.
REFERENCES:
patent: 3645623 (1972-02-01), Patten
Fujitsu Limited
Hostetter Darwin R.
Nelms David C.
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