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Acousto Electro Optical Scanlaser

IP.com Disclosure Number: IPCOM000092222D
Original Publication Date: 1968-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Dakss, M: AUTHOR [+2]

Abstract

The acousto-electro-optical AEO scanlaser combines analog acoustic scanning with digital electro-optic scanning to provide a continuous field in one dimension and a field of precisely registered spots in the orthogonal dimension. Both types of scanning are random access with access times of 1 Vsec for the continuous scanning and less than 0.3 mu sec for the digital scanning.

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Acousto Electro Optical Scanlaser

The acousto-electro-optical AEO scanlaser combines analog acoustic scanning with digital electro-optic scanning to provide a continuous field in one dimension and a field of precisely registered spots in the orthogonal dimension. Both types of scanning are random access with access times of 1 Vsec for the continuous scanning and less than 0.3 mu sec for the digital scanning.

In drawing 1 a degenerate laser cavity includes ultrahigh reflective mirror 10 and mirror 12 having an ultrahigh reflective stripe. Between mirrors 10 and 12 are located crystal slab 14, bias plate 16, linear polarizer 18, singlet lens 20, active laser medium 22, Bragg cell deflector 24, and singlet lens 26.

The laser cavity is of the flat-field geometry and can thus support oscillation of the degenerate set of transverse modes, each member of which is focussed to a spot on one mirror and to the conjugate spot on the other mirror. One- dimensional digital scanning is accomplished with a mode selector consisting of the series combination of polarizer 18, bias plate 16 of uniform birefringence, and LiNbO(3) slab 14, having two opposite sides coated with conducting stripes for application of a transverse electric field in any of several localized regions of such slab. The latter is wide enough to allow only one transverse mode, in the Y- direction, to pass through it. With no applied electric field, all modes have their Q spoiled by the retardation in bias plate 16. One mode is turned on by applying a voltage across a desired oppositely located pair of conducting stripes such as to produce a retardation which brings the mode passing through the region of LiNbO(3) between these stripes above threshold. Digital scanning in the X- direction is then accomplished by scanning from mode to mode.

Continuous scanning in the Y-direction is provided by reactive output coupling via acousto-optic deflection. For this, Bragg cell 24, e.g., a LiNbO(3) crystal, at the center of the cavity deflects a fraction of the oscillating mode so that the deflected beam passes outside the UHR stripe of mirror 12.

In an alternative arrangement, the same crystal, e.g., LiNbO(3) or LiTaO(3), is used for electro-optic switching and for acoustic deflection. An example of a de...