Phase shift detection for use in laser radar ranging systems

Claim 3

The method of claim 1 wherein processing said electrical multiple phase-shifted frequency output and driver frequencies includes: filtering said electrical multiple phase-shifted frequency output to obtain separate corresponding frequency and phase; and phase detecting with respect to corresponding driver frequency signals.

Claim 4

A laser radar ranging system utilizing phase shift detection comprising: a laser for generating a laser beam with an output frequency; a beam splitter for splitting said output beam into a laser and local oscillator beam; an optical modulator driven by multiple frequency drivers which frequency shift said first part of said output frequency to provide multiple shifted frequencies; a brewster angle plate mirror through which said multiple shifted frequencies pass through unaffected; an afocal lens through which said multiple shifts frequency beam is transmitted to a target and a reflected beam received back through said lens which contain shifted multiple frequencies, including corresponding phase shifts, said reflected beam diverted by said plate after received back through said lens; a second beam mirror at which said received beam and said laser oscillator beam is superimposed; a detector which mixes said superimposed beam to remove said laser output frequency and obtain an electrical multiple phase-shifted frequency output as detector output; a signal processor which processes said detector output and said driver frequencies to output separate phase shift information for each corresponding frequency to yield range information therefrom.

Claim 5

A laser radar ranging system utilizing phase shift detection comprising: a laser for generating a laser beam with an output frequency; a beam splitter for splitting said output beam into a laser and local oscillator beam; an optical modulator driven by multiple frequency drivers which frequency shift said first part of said output frequency to provide multiple shifted frequencies; a brewster angle plate mirror through which said multiple shifted frequencies pass through unaffected; an afocal lens through which said multiple shifts frequency beam is transmitted to a target and a reflected beam received back through said lens which contain shifted multiple frequencies, including corresponding phase shifts, said reflected beam diverted by said plate after received back through said lens; a second beam mirror at which said received beam and said laser oscillator beam is superimposed; a detector which mixes said superimposed beam to remove said laser output frequency and obtain an electrical multiple phase-shifted frequency output as detector output; a signal processor which processes said detector output and said driver frequencies to output separate phase shift information for each corresponding frequency to yield range information therefrom.

Claim 6

The system of claim 3 wherein said signal processor further includes: multiple bandpass filters which filter said detector output into separate corresponding frequency with phase; and multiple phase detectors which phase detect said corresponding filter outputs and driver frequencies.