Browse Prior Art Database

TEMPERATURE AND MOISTURE COMPENSATION FOR PLASTIC STRIP LENS

IP.com Disclosure Number: IPCOM000027598D
Original Publication Date: 1998-Feb-28
Included in the Prior Art Database: 2004-Apr-08
Document File: 2 page(s) / 94K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is a method of temperature compensation for a plastic strip lens. Generally, temperature compensation, in optical systems, is accomplished by employing a frame material between a plurality of lenses that expands by an amount necessary to keep an image focused. However, the index of refraction, for plastic, changes about 50 times more as a function of temperature than glass. Accordingly, the thermal expansion coefficient for plastic is approximately 10 times greater than glass, 5 times greater than steel, and 4 times greater than aluminum. Therefore, temperature compensation becomes a central issue for well perforrning plastic optical systems.

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XEROX DISCLOSURE JOURNAL

TEMPERATURE AND MOISTURE Proposed Classification

COMPENSATION FOR PLASTIC STRIP LENS Int. C1. G03g 15/04

U. S. C1.399/199

Moritz P. Wagner

FIG. I I

20 FIG.2

XEROX DISCLOSURE JOURNAL - Vol. 23, No. 1 January/February 1998 35

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TEMPERATURE AND MOISTURE COMPENSATION FOR PLASTIC STRIP LENS (CONT'D)

Proposed is a method of temperature compensation for a plastic strip lens. Generally, temperature compensation, in optical systems, is accomplished by employing a frame material between a plurality of lenses that expands by an amount necessary to keep an image focused. However, the index of refraction, for plastic, changes about 50 times more as a function of temperature than glass. Accordingly, the thermal expansion coefficient for plastic is approximately 10 times greater than glass, 5 times greater than steel, and 4 times greater than aluminum. Therefore, temperature compensation becomes a central issue for well perforrning plastic optical systems.

There is no available material useable as a frame between strip lenses that expands enough to keep the image focused. Thus, FIG. 1 illustrates the proposed frame 10 having expansion bars 14 that move strip lenses 12 in the axis of the optical path through a field- stop 16. Frame 10 is composed of a low expansion material (e.g., steel) and the expansion bars 14 are comprised of a high thermal expansion material. The strip lenses 12 attac...