Optics: image projectors – Lens support – Lens position adjustable
Patent
1976-04-22
1980-05-06
Haroian, Harry N.
Optics: image projectors
Lens support
Lens position adjustable
354 25, G03B 310
Patent
active
042014565
ABSTRACT:
A method and apparatus for detecting the focusing condition of an optical system is disclosed. Different portions of the optical system are alternatively obstructed to form first and second or more images, respectively, of an object. When the optical system is in focus, the aforesaid first and second images coincide and present a single image. When the optical system is out of focus, the first and second images are displaced with respect to one another. Alternately obstructing different portions of the optical system gives the appearance of a moving image when the first and second images are displaced in response to the optical system being out of focus. Alternately obstructing different portions of the optical system gives the appearance of a stationary image when the first and second images coincide in response to the optical system being in focus. Thus the presence of either a stationary or moving image is an indication of the focus condition of the optical system. A method and apparatus are also disclosed for adjusting an optical system into focus in response to the direction of the displacement of the first and second images when the optical system is out of focus. Thus the direction of adjustment of the optical system to restore focus is in response to the relative movement of the first and second images with respect to one another when the focus of the optical system is varied. The disclosed method and apparatus are applicable to the control of focus in photographic cameras, projection systems, range finders, and the like.
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The British Journal of Photography, "Sharp Focus in Enlarging & Copying," p. 556, 9/12/24, by B. Schleicher.
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