Direct Time-of-Flight LiDAR With Sparse Illumination and Low Power
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Solution Overview
Problem
Conventional lidar systems face challenges in reducing power consumption and motion artifacts while maintaining high sensitivity and timing resolution, particularly in applications requiring sparse and efficient 3D imaging.
Innovation Solution
A lidar system with a sparse emitter array and detector array configuration, where each detector pixel has a larger field of detection than the divergence angle of the light beams, allowing for simultaneous activation of all pixels and reduced power consumption by processing detection signals without time-to-digital conversion, and utilizing a structured illumination pattern to minimize overlap and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If all detector pixels are activated simultaneously with a sparse emitter array, then power consumption is reduced, but measurement precision deteriorates due to reduced signal-to-noise ratio
Solution Approach 1:
The detector array is segmented into multiple pixels with different fields of detection, where each pixel is assigned a specific angular region. This segmentation allows simultaneous activation of all pixels while maintaining signal-to-noise ratio through spatial discrimination, as each pixel only detects signals from its assigned region rather than the entire field of view.
Solution Approach 2:
Each detector pixel is assigned a specific local field of detection that is optimized for its position in the array. The local quality of detection is enhanced by matching the field of detection of each pixel to the divergence angle of light beams from specific emitter units, creating localized detection zones that improve signal discrimination while enabling simultaneous operation.
2Measurement precision
If a dense emitter array is used to illuminate the entire field of view, then measurement precision improves, but device complexity and power consumption increase
Solution Approach 1:
Instead of using a dense emitter array that illuminates the entire field of view, the system uses a sparse emitter array that illuminates only specific regions. This partial action approach reduces the number of emitters and overall system complexity while maintaining sufficient measurement precision through the strategic placement of emitters and corresponding detector pixel assignments.
Solution Approach 2:
The detector pixels are designed with multi-functionality, where each pixel can detect signals from multiple emitter units depending on the divergence angle of the light beams. This universality allows a sparse emitter array to be effectively utilized, as each detector pixel serves multiple potential emitter sources, thereby reducing the overall number of emitters needed while maintaining measurement precision.
3Measurement precision
If time-to-digital conversion is performed for each detector pixel, then measurement precision improves, but processing time and power consumption increase
Solution Approach 1:
The system merges the timing information from multiple detector pixels into a unified processing approach. Instead of performing separate time-to-digital conversion for each pixel, the system combines the detection signals and performs timing measurement collectively, thereby reducing processing time and power consumption while maintaining timing resolution through coordinated processing of multiple pixel outputs.
Solution Approach 2:
The system uses periodic action in the form of synchronized detection cycles where all detector pixels are activated and processed in periodic frames. This periodic processing allows efficient batch handling of detection signals, reducing the computational overhead associated with continuous time-to-digital conversion while maintaining precise timing measurement through synchronized sampling.
4Use of energy by stationary object
If the field of detection of detector pixels is made larger than the divergence angle of light beams, then power consumption is reduced, but crosstalk between adjacent pixels increases
Solution Approach 1:
Each detector pixel is assigned a specific local field of detection that is carefully optimized to match the divergence angle of light beams from corresponding emitter units. This local quality optimization ensures that while the field of detection is sufficiently large to capture all relevant signals, it is precisely controlled to minimize overlap and crosstalk with adjacent pixels through spatial discrimination.
Solution Approach 2:
The system employs feedback mechanisms to monitor and adjust the field of detection parameters of detector pixels. By continuously monitoring the detection signals and adjusting the field of detection parameters, the system optimizes the balance between capturing sufficient signals and minimizing crosstalk, thereby reducing power consumption while controlling harmful interference between adjacent pixels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves lower angular-resolution 3D point cloud data acquisition with reduced power consumption and minimal motion artifacts, enabling faster throughput and efficient processing of detection signals.
Implementation Method 1
The high reverse bias voltage generates a sufficient magnitude of electric field such that a single charge carrier introduced into the depletion layer of the device can cause a self-sustaining avalanche via impact ionization
Implementation Method 2
The initiating charge carrier can be photo-electrically generated by means of a single incident photon striking the high field region
Implementation Method 3
Direct time of flight measurement includes directly measuring the length of time between emitting radiation by emitter element(s) of the lidar system and sensing the radiation at detector element(s) of the lidar system after reflection from an object or other target
Implementation Method 4
one or more light emitter units (including one or more semiconductor lasers, such as surface- or edge-emitting laser diodes; generally referred to herein as emitters, which output respective light signals)
Data Source
AI summary
A Light Detection and Ranging (LIDAR) system includes a light source configured to emit a plurality of light beams having respective divergence angles over respective fields of illumination, and a detector array comprising plurality of detector pixels having respective fields of detection and configured to output respective detection signals responsive to light incident thereon. The respective fields of detection of the detector pixels are greater than or equal to the respective divergence angles of the light beams. Related devices and methods are also discussed.