Beam steering LADAR sensor
In one embodiment, a ladar system includes a laser transmitter with at least one semiconductor laser having a pulsed laser light output. A laser drive circuit is connected to said at least one semiconductor laser and adapted to electrically drive said at least one semiconductor laser in a predetermined sequence. A laser beam steering mechanism is adapted to scan the pulsed laser light output sequentially through the field of view. A two-dimensional array of light sensitive detectors receive reflected light and an integrated circuit calculates a direct time of flight distance measurement.
1. A ladar system mountable to a vehicle, said system comprising:
a laser transmitter comprising at least one semiconductor laser having a pulsed laser light output configured to transmit light through a transmitting optic adapted to illuminate a reflecting surface in a field of view;
a laser drive circuit connected to said at least one semiconductor laser and adapted to electrically drive said at least one semiconductor laser in a predetermined sequence;
a laser beam steering mechanism adapted to scan the pulsed laser light output sequentially through the field of view;
a time zero reference circuit having a time zero reference electrical output configured to signal the beginning of a pulsed laser light transmission;
receiving optics adapted to collect and condition the pulsed laser light reflected from the reflecting surface;
a two-dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, each of said light sensitive detectors configured to intercept a pixellated portion of the pulsed laser light output reflected from the reflecting surface, and each light sensitive detector having an output configured to produce an electrical response signal;
a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors; and
a readout integrated circuit with a clock circuit and a plurality of unit cell electrical circuits;
each of said unit cell electrical circuits having an input connected to said clock circuit and to said time zero reference electrical output, and having an amplifier with an input connected to one of said light sensitive detector outputs, and each amplifier having an output, and a pulse detection circuit connected to said amplifier output, and said pulse detection circuit having a termination output, a counter connected to said time zero reference electrical output and to said clock circuit, said counter started counting by the time zero reference electrical output, and said counter connected to, and stopped counting by the termination output, and the counter having an output proportional to the distance to the reflecting surface, thereby establishing a direct time of flight distance measurement.
2. The ladar sensor of claim 1 wherein said at least one semiconductor laser is selected from the set of an edge emitting laser and a surface emitting laser.
3. The ladar sensor of claim 1 wherein said beam steering mechanism is a microelectromechanical system.
4. The ladar sensor of claim 3 wherein said microelectromechanical system is formed in silicon.
5. The ladar system of claim 1 wherein said predetermined sequence is a line-by-line illumination of the field of view.
6. The ladar system of claim 1 wherein said predetermined sequence is a pixel-by-pixel illumination of the field of view.
7. The ladar sensor of claim 1 wherein said ladar sensor is integrated into an assembly selected from the set of a headlight, a turn signal, taillight, parking light, and brake light.
8. The ladar sensor of claim 1 wherein said two-dimensional array of light sensitive detectors is formed in a material selected from the set of silicon, indium gallium arsenide, indium gal
lium arsenide phosphide, aluminum gallium arsenide, and indium gallium nitride.
9. The ladar sensor of claim 1 wherein said two-dimensional array of light sensitive detectors is adapted to provide multiplication of at least one photoelectron.
10. The ladar sensor of claim 1 wherein said two-dimensional array of light sensitive detectors is selected from the set of an avalanche photodiode array and an image tube focal plane array.
11. A ladar system comprising:
a laser transmitter comprising at least one semiconductor laser configured to produce a pulsed laser light output through a transmitting optic adapted to illuminate a field of view;
a laser drive circuit connected to said at least one semiconductor laser and adapted to electrically drive said at least one semiconductor laser in a predetermined sequence;
a laser beam steering mechanism adapted to scan the pulsed laser light output sequentially through the field of view;
a time zero reference circuit configured to signal the beginning of a pulsed laser light transmission;
receiving optics adapted to collect and condition the pulsed laser light reflected from reflecting surface in the field of view;
a two-dimensional array of light sensitive detectors positioned at a focal plane of said receiving optics, each of said light sensitive detectors configured to receive a pixellated portion of the pulsed laser light output reflected from the reflecting surface and produce an electrical response signal in response to receiving the pixelated portion of the pulsed laser light output;
a detector bias circuit connected to a voltage distribution grid of said array of light sensitive detectors; and
a plurality of unit cell electrical circuits, each of said unit cell electrical circuits coupled to one of said light sensitive detector outputs and said time zero reference circuit and configured to determine a direct time of flight distance measurement to the reflecting surface.