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Pathlength Compensated Light Deflector

IP.com Disclosure Number: IPCOM000090878D
Original Publication Date: 1969-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Habegger, MA: AUTHOR

Abstract

This reflection type light deflector is pathlength-compensated without the use of any extra optical elements. The light deflecting portion of the external reflection type light deflector has combinations of birefringent devices 1 and 2 and isotropic plates 3 and 4. Plate 3 can be a coating fixed to the nonincident side of device 1. The latter has an optic axis 5 which is perpendicular to the plane of incidence of light beam 6. Optic axis 7 of device 2 is in a plane parallel to the planes of incidence of the light. The entire light deflecting stage is immersed in a surrounding media 10 such as an oil bath having an index of refraction substantially equal to the higher index of refraction of the birefringent device.

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Pathlength Compensated Light Deflector

This reflection type light deflector is pathlength-compensated without the use of any extra optical elements. The light deflecting portion of the external reflection type light deflector has combinations of birefringent devices 1 and 2 and isotropic plates 3 and 4. Plate 3 can be a coating fixed to the nonincident side of device 1. The latter has an optic axis 5 which is perpendicular to the plane of incidence of light beam 6. Optic axis 7 of device 2 is in a plane parallel to the planes of incidence of the light. The entire light deflecting stage is immersed in a surrounding media 10 such as an oil bath having an index of refraction substantially equal to the higher index of refraction of the birefringent device. To accomplish the light deflection providing pathlength-compensated outputs 8 and 9 without the use of any extra optical elements, the incident surfaces of the birefringent devices 1 and 2 are arranged respectively, at the angles alpha and beta. Each of these angles is less than 90 degrees - theta critical but is not equal to the other. By removing any parallelism between the incident faces of devices 1 and 2, the pathlength-compensation is achieved when the relationships d = 2d1 (d-beta)/sin(3 beta-d) and d2 = d1 - d are satisfied.

This light deflector avoids any problem of astigmatism in the output beams 8 and 9 as a light beam propagated as a set of extraordinary rays never traverses a birefringent device. The l...