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Pathlength Compensation for Light Deflector

IP.com Disclosure Number: IPCOM000090581D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Lipp, J: AUTHOR

Abstract

Insertion of an optical block for pathlength compensation in the Path of a light beam, propagated as a set of extraordinary rays through a light deflector, is not feasible when the deflected extraordinary rays are close to or overlap the beam propagated as a set of ordinary rays. Pathlength compensation is provided in a reflection type light deflector that is not dependent on beam separation.

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Pathlength Compensation for Light Deflector

Insertion of an optical block for pathlength compensation in the Path of a light beam, propagated as a set of extraordinary rays through a light deflector, is not feasible when the deflected extraordinary rays are close to or overlap the beam propagated as a set of ordinary rays. Pathlength compensation is provided in a reflection type light deflector that is not dependent on beam separation.

A light deflection stage includes birefringent plate-isotropic element combinations 10 and 11. In combination 10, birefringent plate 12 has isotropic element 13 deposited as a coating on its nonincident face. In combination 11, isotropic element 15 is spaced from birefringent element 14 and is adjustable with respect to it to control the position of output beams 16 and 17 in focal plane
18. The distance between output beams 16 and 17 is determined by the difference between distances T1 and T2. In each instance, this distance is measured from the incident face of the birefringent plate to the incident face of the isotropic element.

When incident linearly polarized light beam 19 is propagated as a set of extraordinary rays, it is reflected at the incident face of plate 12 as beam 20. As the optic axis of plate 14 is normal to the optic axis of plate 12, plate 14 accepts beam 20 as a set of ordinary rays passing it for reflection at the incident face of element 15 to provide beam 16. When beam 19 is propagated as a set of ordinary rays, it is transmitted through plate 12 for reflection at the incident face of element 13 as beam 21. The latter is in...