| CPC G01S 17/89 (2013.01) [G01S 7/484 (2013.01); G01S 7/4863 (2013.01); G01S 7/497 (2013.01)] | 17 Claims |
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1. A lidar system comprising:
a laser transmitter system; and
a receiver system;
wherein said laser transmitter system includes:
a seed laser system including a wavelength-tunable seed laser about a center wavelength which emits laser pulses of a laser beam at selected wavelength points, and switches from one wavelength to another wavelength within a switching time of less than 200 ns;
a fiber amplifier which amplifies said laser pulses up to 200 kW and collimates said laser beam;
a first transmitter grating which receives said laser beam from said fiber amplifier;
a transmitter telescope, including a primary mirror and a secondary mirror; and
a pair of relay lenses or mirrors;
wherein said laser beam is directed from said first transmitter grating via said pair of relay lenses or mirrors, to said secondary mirror and then to said primary mirror, to image said first transmitter grating on said primary mirror, in order to minimize laser beam wander on said primary mirror; and
wherein said first transmitter grating diffracts and steers said collimated laser beam from said fiber amplifier by wavelength via said primary mirror to a surface, to an arbitrary subset of up to 2000 resolvable footprints along a cross-track direction on said surface at a beam pointing angle switching time of less than 200 ns, such that said footprints which are illuminated by said laser beam from said first transmitter grating on to said surface are imaged in three-dimensions (3D), wherein said center wavelength of said laser transmitter system and a receiver wavelength of said receiver system are centered about any laser wavelength including one of a 1035 nm, a 1550 nm, a 2050 nm, or a 518 nm wavelength:
wherein said receiver system comprises:
a receiver telescope including a primary mirror and a secondary mirror, said receiver telescope which collects return laser pulses of said laser beam returning from said surface;
a first receiver grating which filters out solar background radiation spatially and spectrally for all said footprints illuminated by said laser beam returning from said surface with different wavelengths; and
a linear detector array on which said footprints from said surface are imaged;
wherein said return laser beam from a central footprint of said footprints, at said center wavelength, travels along an optical axis from said receiver telescope to said linear detector array; and
wherein said footprints are distributed across multiple of detector pixels, such that a solar background noise and a detector dark-noise on each pixel of said linear detector array are decreased while a bandwidth of said linear detector array is increased; and
wherein said receiver system further comprises:
an entrance slit disposed between said receiver telescope and said first receiver grating;
wherein said footprints on said surface are imaged by said receiver telescope onto said entrance slit which is oriented along said cross-track direction to allow images of said footprints to pass while limiting a receiver individual field of view (iFOV) of each of said footprints in an along-track direction;
wherein successive footprints on said surface illuminated by said laser beam at a fixed cross-track pointing angle forms a track of footprints in said along-track direction; and
wherein said receiver iFOV of each of said footprints in said cross-track direction is limited by a width of no more than two detector pixels.
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