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Aberrant Holographic Focusing Element for Post-Objective Holographic Deflector

IP.com Disclosure Number: IPCOM000042589D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR

Abstract

This article describes a technique for making an aberration-containing holographic lens which, when used with a linear holographic deflector, provides a largely aberration-free, focused deflected beam. The linear holographic deflector to be used during scanning (or a replica) is used in making the aberration-containing holographic lens. A known type of optical scanner includes a rotating holographic disc. A post-objective scanner is one in which the laser beam is focused by a lens before reaching the disc. One disadvantage of conventional post-objective scanners is that the focused beam is distorted or aberrated by the facets of the disc even when the facets are simple plane wave gratings. The type of distortion can be seen in Fig.

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Aberrant Holographic Focusing Element for Post-Objective Holographic Deflector

This article describes a technique for making an aberration-containing holographic lens which, when used with a linear holographic deflector, provides a largely aberration-free, focused deflected beam. The linear holographic deflector to be used during scanning (or a replica) is used in making the aberration- containing holographic lens. A known type of optical scanner includes a rotating holographic disc. A post-objective scanner is one in which the laser beam is focused by a lens before reaching the disc. One disadvantage of conventional post-objective scanners is that the focused beam is distorted or aberrated by the facets of the disc even when the facets are simple plane wave gratings. The type of distortion can be seen in Fig. 1 where a collimated beam 10 (defined by rays A, B, C) is focused by a conventional lens 12 before reaching a rotating holographic element 14. The corresponding rays A', B', C' of the deflected or first order beam are not focused to the same point because of aberrations introduced by element 14. Referring to Fig. 2, the aberrations can be cancelled out if the conventional lens 12 is replaced with a holographic lens 16 which is produced by interfering a collimated reference beam with a diverging object beam (OBJ) which is transmitted through the same holographic facet (or a replica) which will be used during scanning. If a reflective hologram is to be used a...