Modulator for electrical signals processed in a laser-acoustic delay line

Apparatus employing coherent light beams for processing an electrical signal provided by an electrical signal source, comprising:

• means for heterodyning beams of light on a plurality of paths with each other to provide an electrical output signal having characteristics defined by differences between the heterodyned beams;
• a source of coherent light providing a plurality of beams along respective paths to said heterodyning means;
• optical means disposed in one of said paths to receive components of coherent light of the corresponding beam for phase shifting selected components thereof according to an encoding pattern thereby providing a phase modulated light beam in the related path;
• a laser-acoustic processing delay line having at one end a transducer connected to the electrical signal source for generating an acoustic traveling wave along an axis of said processing delay line, said processing delay line being disposed in one of said paths to receive the related beam at the Bragg angle to said axis at a location thereon, a diffracted light beam being provided in response to interaction between the related beam and said acoustic wave;
• and
• means for providing continuous, non-incremental moving of said optical means with respect to the related one of said paths, thereby providing a time varying phase modulation of the light beam in the related path.