Light beam deflector emitting a pair of output light beams on planes

Abstract

In a light beam deflector comprising an acoustic medium supplied with an incident light beam along an optical axis to selectively emit a pair of first-order diffracted output beams and first and second transducers selectively energized by an electric signal to propagate first and second acoustic waves into the medium, respectively, the acoustic medium has a hexahedral shape defining an incident surface for the incident beam, an output surface opposite to the incident surface, and four side surfaces contiguous to the incident and the output surfaces. The first and the second transducers are laid on two adjacent ones of the side surfaces so that wave fronts of the first and the second acoustic waves intersect relative to each other at a substantially right angle in the medium. The incident beam is inclined to both wave fronts by the Bragg angle. A plane defined by one of the output beams and the optical axis intersects with another plane defined by the other output beam and the optical axis. Preferably, an acoustic absorber is covered on two side surfaces opposite to the above-mentioned side surfaces for the transducers.