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Holographic Optical Element And Variable Laser Beam Attenuator

IP.com Disclosure Number: IPCOM000062250D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Fortenberry, RS: AUTHOR

Abstract

This article describes a technique for fabricating and using a holographic optical element (HOE) to variably attenuate a plane polarized laser beam. The HOE is exposed and processed to produce a modulation factor at which a useful difference exists between the S polarization diffraction efficiency and the P polarization diffraction efficiency. By rotating the reference/ object exposure plane of the hologram relative to the plane of polarization of the laser, the amount of light diffracted into the first order beam can be adjusted.

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Holographic Optical Element And Variable Laser Beam Attenuator

This article describes a technique for fabricating and using a holographic optical element (HOE) to variably attenuate a plane polarized laser beam. The HOE is exposed and processed to produce a modulation factor at which a useful difference exists between the S polarization diffraction efficiency and the P polarization diffraction efficiency. By rotating the reference/ object exposure plane of the hologram relative to the plane of polarization of the laser, the amount of light diffracted into the first order beam can be adjusted.

The HOE is exposed using a normal reference beam and an off-axis object beam. The goal of the exposure/processing steps is to achieve a modulation factor of f.

When the hologram is placed in the path of a polarized laser beam, the amount of light diffracted into the first order beam (and thus the amount remaining in the zero order beam) depends on the plane of polarization of the laser beam relative to the reference/object exposure plane of the hologram. The hologram can be used to variably attenuate the strength of the zero order beam by rotating the HOE about the beam axis.

The plane of polarization of the attenuated beam is rotated slightly relative to its original plane. Where the plane of polarization is critical, a half wave plate can be inserted into the beam path following the HOE to return the plane of polarization to its initial position. Alternatively, the laser c...