Inverted time impulsed bragg angle matched filter

Claim 2

A matched filter system for recognizing a coded pulse of a given character comprising: a source of monochromatic spatially coherent light rays; means for modulating said light rays in response to a first modulating signal; means for modulating said light rays in response to a second modulating signal; a wave plate to intercept the coded modulated wave; means for combining the monochromatic spatially coherent light rays with the intercepted coded modulated wave; and a lens to focus the combined wave fronts onto a photodetector.

Claim 3

A matched filter system as described in claim 1 wherein: said modulating means comprises an ultrasonic delay cell having first and second piezoelectric transducers; and the modulation is phase modulation.

Claim 4

A matched filter system as described in claim 2 wherein: said delay cell is positioned so that said light rays impinge upon the delay cell at the Bragg Angle.

Claim 5

A matched filter system as described in claim 3 wherein: said delay cell is positioned so that said light rays impinge upon the delay cell at the angle theta , where theta is satisfied by equation n lambda 2 Omega Sin theta where n the order of diffraction lambda wavelength of the monochromatic spatially coherent light source Omega ultrasonic wavelength theta angle of incidence of the monochromatic spatially coherent light to the direction of the ultrasonic velocity.

Claim 6

A matched filter system as described in claim 4 wherein: a first modulating signal is applied to said first means for modulating said light rays; an impulse is applied to said second means for modulating said light rays; so that the output of said photodetector effectively impulses the filter with a reversed time read out.

Claim 7

A matched filter system as described in claim 5 wherein: the first modulating signal is the output of the photodetector.

Claim 8

A matched filter system as described in claim 5 wherein said wave plate consists of sodium dioxide deposited through a mask upon a quartz face to create a relief on the surface such that the phase delay due to the varying optical thickness will compensate the phase modulated code and produce a plane wave output.

Claim 9

A matched filter system as described in claim 5 wherein said wave plate consists of aluminum deposited through a mask upon an aluminum reflector to create a relief on the surface such that the phase delay due to the varying optical thickness will compensate the phase modulated code and produce a plane wave output.

Claim 10

A matched filter system as described in claim 5 wherein said wave plate consists of a hologram.

Claim 11

A matched filter system as described in claim 5 wherein said photodetector has an aperture comprised of a diffraction limited pin hole.

Claim 12

A matched filter system as described in claim 10 wherein the means for combining the monochromatic spatially coherent light rays with the detected coded modulated wave comprises: a first semitransparent mirror to split the monochromatic spatially coherent light into two beams; the first beam impinges upon the ultrasonic delay cell, and the second beam impinges upon a first fully reflective mirror; a second fully reflective mirror to reflect the second beam reflected from said first fully reflective mirror onto a second semitransparent mirror; and a second semitransparent mirror to combine the second beam with the detected coded modulated wave.