Eye-safe coherent laser radar
AssigneeThe Board of Trustees of the Leland Stanford Jr. University
InventorsRobert L. Byer, Thomas J. Kane
Life of this patent
Estimating the term…
Abstract
In an eye-safe coherent laser radar, a laser diode optically pumps a solid state non-planar ring laser to produce the coherent output laser radiation. The laser radiation is passed through a Faraday isolator to an optically pumped slab three-stage linear amplifier imparting 56 db gain. A telescope transmits the amplified laser radiation to illuminate a target. Optical radiation returned from the target is collected by the telescope and focused into a single transverse mode fiber-optic waveguide for combination in the fiber with reference lasant radiation by means of a single mode fiber coupler. The combined optical radiation is then detected by a photodetector to produce a difference frequency output representative of parameters of the target.
Claims27
In a method for coherently detecting returned eye-safe laser radiation, the steps of:
- optically pumping a solid state laser gain medium with optical pumping radiation emanating from a semiconductive diode;
- resonating lasant radiation emanating from the optically pumped laser gain medium to produce coherent output lasant radiation of an eye-safe wavelength in excess of 1.5 .mu.m;
- amplifying the coherent output lasant radiation in an optical amplifier to produce amplified coherent eye-safe output lasant radiation;
- transmitting the amplified output eye-safe lasant radiation from a transmitter station;
- receiving at a receiving station the lasant radiation returned from a target intercepted by the transmitted lasant radiation;
- collecting the received eye-safe lasant radiation and propagating the same over a single mode fiber-optic waveguide;
- and
- mixing the received lasant radiation as propagated over the single mode fiber-optic waveguide with reference coherent lasant radiation to derive a difference frequency output signal representative of parameters associated with the target.
The method of claim l including the step of:
- sampling the coherent output lasant radiation to produce the reference lasant radiation for mixing with the received lasant radiation.
The method of claim l including the step of:
- optically pumping a second solid state member of lasant material with optical pumping radiation derived from a semiconductive diode to excite reference lasant transitions to produce the reference lasant radiation for mixing with the received lasant radiation.
In an eye-safe coherent laser radar:
- a solid state laser gain medium;
- optical pumping means for optically pumping said laser gain medium with optical pumping radiation emanating from a semiconductive diode;
- optical resonator means optically coupled to said laser gain medium for resonating lasant radiation emanating from said optically pumped laser gain medium to produce coherent output laser radiation of an eye-safe wavelength in excess of 1.5 .mu.m;
- optical amplifier means optically coupled to said laser gain medium for amplifying the coherent eye-safe output lasant radiation;
- transmitter station means optically coupled to said optical amplifier means for transmitting the amplified output eye-safe lasant radiation over a path to illuminate a target;
- receiver means for receiving the output lasant radiation returned from the illuminated target;
- a single transverse mode fiber-optic waveguide optically coupled to said receiver means and disposed to receive and propagate therein as a single transverse mode returned and received output lasant radiation;
- combining means for combining the returned and received output lasant radiation as propagated over said single mode fiber-optic waveguide with reference coherent lasant optical radiation;
- and
- detecting means optically coupled to the combined optical radiation for detecting a difference frequency output signal therebetween representative of parameters associated with the illuminated target.
In a coherent laser radar:
- a solid state laser gain medium;
- optical pumping means for optically pumping said laser gain medium with optical pumping radiation emanating from a semiconductive diode;
- optical resonator means optically coupled to said laser gain medium for resonating lasant radiation emanating from said optically pumped laser gain medium to produce coherent output lasant radiation;
- optical amplifier means optically coupled to said laser gain medium for amplifying the coherent output lasant radiation;
- transmitter station means optically coupled to said optical amplifier means for transmitting the amplified output lasant radiation over a path to illuminate a target;
- receiver means for receiving the output lasant radiation return from the illuminated target;
- a single transverse mode fiber-optic waveguide optically coupled to said receiver means and disposed to receive and propagate therein as a single transverse mode the returned and received output lasant radiation;
- combining means for combining the returned and received output lasant radiation as propagated over said single mode fiber-optic waveguide with reference coherent lasant radiation;
- and
- detecting means optically coupled to the combined optical radiation for detecting a difference frequency output signal therebetween representative of parameters associated with the target.
Dependencies are inferred from the claim text.