Scanning laser time of flight 3D imaging
First Claim
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1. An apparatus comprising:
- a laser light source;
a pulse shaping circuit to drive the laser light source with pulses having an abrupt change in amplitude;
a photodetector to detect reflected light pulses;
a differentiator coupled to the photodetector to differentiate detected pulses;
a compression circuit to compress output signals from the differentiator;
an amplifier to receive compressed signals from the compression circuit and to generate differential output signals;
a detection circuit to detect when the differential output signals cross each other; and
an integrator responsive to the detection circuit for time measurement.
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Abstract
Laser light pulses are reflected off a scanning mirror. A time-of-flight distance measurement device receives reflected light pulses and determines distances. The light pulses have abrupt changes in amplitude. Reflected pulses are differentiated to reduce sensitivity to amplitude variations. Differentiated pulses may be compressed to keep the receiver from saturating. Distance measurements are combined with location information to produce a 3D image of a surface.
18 Citations
20 Claims
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1. An apparatus comprising:
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a laser light source; a pulse shaping circuit to drive the laser light source with pulses having an abrupt change in amplitude; a photodetector to detect reflected light pulses; a differentiator coupled to the photodetector to differentiate detected pulses; a compression circuit to compress output signals from the differentiator; an amplifier to receive compressed signals from the compression circuit and to generate differential output signals; a detection circuit to detect when the differential output signals cross each other; and an integrator responsive to the detection circuit for time measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus comprising:
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a laser light source; a pulse shaping circuit to drive the laser light source with pulses having an abrupt change in amplitude; a photodetector to detect reflected light pulses; a differentiator coupled to the photodetector to differentiate detected pulses; an amplifier to receive signals from the differentiator and to generate differential output signals; a detection circuit to detect when the differential output signals cross each other; a power control circuit to modify signal gain at an input to the laser light source in response to a first light pulse train; and an integrator responsive to the detection circuit for time measurement to integrate over a second light pulse train for time measurement. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A mobile device comprising:
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a scanning laser projector having at least one visible laser light source and a scanning mirror; and a time of flight distance measurement device that includes a nonvisible laser light source to illuminate the scanning mirror with laser light pulses, and that includes a receive signal path that differentiates signals representing reflected laser light pulses, and a power control circuit responsive to the receive signal path; wherein the power control circuit modifies a power level of a second train of light pulses emitted by the nonvisible laser light source in response to reflections from a first train of light pulses emitted by the nonvisible laser light source. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification