Accurate photo detector measurements for LIDAR
First Claim
1. A method of using an optical measurement system, the method comprising:
- transmitting N pulse trains from a light source as part of an optical measurement, each of the N pulse trains including one or more pulses from the light source and corresponding to a different time interval that is triggered by a start signal, and wherein N is an integer greater than one;
detecting photons of the N pulse trains by a photosensor of the optical measurement system, thereby generating data values at a plurality of time points;
for each of the N pulse trains, assigning a weight to the data values at time points within the time interval corresponding to the pulse train, thereby obtaining weighted values, wherein at least two of the N pulse trains are assigned different weights and have different pulse patterns;
determining a histogram corresponding to the weighted values in a plurality of time bins, wherein determining a counter of the histogram at a particular time bin includes accumulating the weighted values at time points within the particular time bin across a plurality of time intervals; and
detecting a signal corresponding to the N pulse trains within the histogram.
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Abstract
A light ranging system can include a laser device and an imaging device having photosensors. The laser device illuminates a scene with laser pulse radiation that reflects off of objects in the scene. The reflections can vary greatly depending on the reflecting surface shape and reflectivity. The signal measured by photosensors can be filtered with a number of matched filter designed according to profiles of different reflected signals. A best matched filter can be identified, and hence information about the reflecting surface and accurate ranging information can be obtained. The laser pulse radiation can be emitted in coded pulses by allowing weights to different detection intervals. Other enhancements include staggering laser pulses and changing an operational status of photodetectors of a pixel sensor, as well as efficient signal processing using a sensor chip that includes processing circuits and photosensors.
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Citations
30 Claims
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1. A method of using an optical measurement system, the method comprising:
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transmitting N pulse trains from a light source as part of an optical measurement, each of the N pulse trains including one or more pulses from the light source and corresponding to a different time interval that is triggered by a start signal, and wherein N is an integer greater than one; detecting photons of the N pulse trains by a photosensor of the optical measurement system, thereby generating data values at a plurality of time points; for each of the N pulse trains, assigning a weight to the data values at time points within the time interval corresponding to the pulse train, thereby obtaining weighted values, wherein at least two of the N pulse trains are assigned different weights and have different pulse patterns; determining a histogram corresponding to the weighted values in a plurality of time bins, wherein determining a counter of the histogram at a particular time bin includes accumulating the weighted values at time points within the particular time bin across a plurality of time intervals; and detecting a signal corresponding to the N pulse trains within the histogram. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A light ranging system comprising:
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a light source configured to provide pulses; a sensor integrated circuit that includes; a plurality of photosensors corresponding to different fields of view, each photosensor of the plurality of photosensors including a plurality of photodetectors that when triggered by photons are configured to output binary signals indicating the photons have been detected; timing circuitry configured to determine times for when photons are detected based on the binary signals; and histogram circuitry configured to determine and store counters that each correspond to a number of photodetectors of a photosensor triggered during a time bin for each photosensor of the plurality of photosensors, thereby creating a histogram that is usable to determine a received time of one or more pulses from the light source that reflected from an object to each photosensor of the plurality of photosensors. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An optical measurement system comprising:
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a light source configured to provide pulses; a photosensor; and circuitry configured to; transmit N pulse trains from the light source as part of an optical measurement, each of the N pulse trains including one or more pulses from the light source and corresponding to a different time interval that is triggered by a start signal, and wherein N is an integer greater than one; detect photons of the N pulse trains by the photosensor of the optical measurement system, thereby generating data values at a plurality of time points; for each of the N pulse trains, assign a weight to the data values at time points within the time interval corresponding to the pulse train, thereby obtaining weighted values, wherein at least two of the N pulse trains are assigned different weights and have different pulse patterns; determine a histogram corresponding to the weighted values in a plurality of time bins, wherein a determining counter of the histogram at a particular time bin includes accumulating the weighted values at time points within the particular time bin across a plurality of time intervals; and detect a signal corresponding to the N pulse trains within the histogram. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification