Multi-beam emitting device having an acoustooptic element

Abstract

A multi-beam emitting device which splits a light beam emitted from a light source into a plurality of beams with a beam splitter to emit a plurality of beams. As the beam splitter, an optical waveguide type acoustooptic element or the like is used. A multi-beam emitting device according to the present invention has a beam splitter which drives an acoustooptic element with a plurality of electric signals with different frequencies applied thereto so as to deflect a light beam emitted from a light source and split the light beam into a plurality of beams, a signal generator which generates the electric signals with different frequencies which are used for the drive of the acoustooptic element, a modulating circuit which turns on and off the electric signals generated by the signal generater individually based on a data signal, an intensity control circuit which controls the light source to change the intensity of the light beam emitted therefrom. Another multi-beam emitting device has a beam splitter which deflects a light beam emitted from a light source and splits the light beam into an even number of beams, a shutting member which shuts out a half of the beams, a modulating circuit which controls the beam splitter so that the total quantity of light of the beams which are emergent from the beam splitter and not shut out by the shutting member and the beams which are emergent from the beam splitter and shut out by the shutting member will be constant. Further, in these multi-beam emitting devices, the deflecting position of the light beam and the beam waist position of the light beam are inside the optical waveguide type acoustooptic element at a specified distance from each other.