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Short Length Optical System

IP.com Disclosure Number: IPCOM000074068D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Wohl, RJ: AUTHOR

Abstract

A fly's-eye lens (multiple lenslets) L(1) is placed very close to an object 0, forming multiple images in plane I(1), as shown. By the principle of optical reversibility, by placing a mirror at I(1), the light retraces its path and reconstitutes an image of 0 at that plane. How consider this folded system (with mirror) to be unfolded. By placing a similar fly's-eye lens at L(2), at I(2) the erect image of the object is formed. Alternatively, it is possible to use cylindrical lenslets in which case L(1) (and L(2)) will each consist of two such lenses with axes at right angles. Furthermore, the usual penalty of using large lenses ( optical errors increasing as well as expense) is not experienced here. Therefore large fields are accommodated, still maintaining very short-focal length, thereby conserving space.

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Short Length Optical System

A fly's-eye lens (multiple lenslets) L(1) is placed very close to an object 0, forming multiple images in plane I(1), as shown. By the principle of optical reversibility, by placing a mirror at I(1), the light retraces its path and reconstitutes an image of 0 at that plane. How consider this folded system (with mirror) to be unfolded. By placing a similar fly's-eye lens at L(2), at I(2) the erect image of the object is formed. Alternatively, it is possible to use cylindrical lenslets in which case L(1) (and L(2)) will each consist of two such lenses with axes at right angles. Furthermore, the usual penalty of using large lenses ( optical errors increasing as well as expense) is not experienced here. Therefore large fields are accommodated, still maintaining very short-focal length, thereby conserving space.

For fixed-focus applications, the distance between L(1) and L(2) is fixed. Therefore, the lenses may be formed on the two sides of a block of Lucite, or glass, etc. An example of this is the use of such a lens system as an oscilloscope camera, or a terminal printer where hard copy is desired of an image on an oscilloscope screen. In this case, the object distance is the thickness of the CRT faceplate. The photosensitive material is placed at an equivalent (and very short) distance from the second lens. This provides an efficient illumination system, approaching that using optical fibers.

For variable-focus applications, the separati...