LiDAR Beam Steering with Synchronized SPAD Actuation
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Solution Overview
Problem
Existing LiDAR sensors face challenges in achieving accurate high-resolution depth imaging in uncontrolled environments due to environmental factors like background light, signal losses, and manufacturing limitations, leading to inflexible trade-offs between optical aperture, power consumption, and operational constraints.
Innovation Solution
The implementation of a LiDAR system with a laser light source that adjusts emissive power and a SPAD detector array, where the laser light source emits beams at adjustable power levels and is scanned across the target scene, allowing for high-irradiance illumination spots and selective actuation of SPADs based on distance, reducing background noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser light source emits at high power level continuously, then the signal-to-noise ratio is improved, but the power consumption increases
Solution Approach 1:
The system dynamically adjusts the laser light source power level between low and high based on real-time distance measurements. The controller switches between power levels depending on whether targets are within normal range or exceed threshold distance, optimizing the balance between signal quality and power consumption.
Solution Approach 2:
The invention changes the operational parameter (power level) of the laser light source based on measured distance conditions. When targets are detected beyond threshold distance, the system transitions from low power to high power emission to maintain adequate signal-to-noise ratio for accurate depth imaging.
2Length of stationary object
If the laser light source emits at high power level, then the detection range is extended, but the background noise increases
Solution Approach 1:
The system dynamically switches between low and high power levels based on detected target distances. High power is activated only when targets exceed threshold distance, extending detection range while minimizing background noise generation during normal operation when targets are within standard range.
3Productivity
If the beam scanning speed is increased, then the imaging frame rate is improved, but the time-of-flight measurement precision deteriorates
Solution Approach 1:
The system uses periodic pulsed illumination with synchronized detection windows. The beam scanning follows a periodic pattern while time-of-flight measurements are taken during specific measurement windows, allowing frame rate optimization without sacrificing measurement precision through proper timing synchronization.
4Reliability
If the SPAD array operates with high sensitivity, then the detection capability is improved, but the false detection rate increases
Solution Approach 1:
The system performs preliminary distance estimation using low-power illumination before activating high-power emission. This preliminary action allows the system to prepare appropriate detection sensitivity settings and threshold values, reducing false detections while maintaining high detection capability for actual targets.
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
This approach enables compact, low-cost LiDARs to achieve accurate high-resolution depth imaging in uncontrolled environments by optimizing illumination and detection parameters, increasing lateral resolution without reducing sensing element size and maintaining a high signal-to-noise ratio.
Implementation Method 1
A light source is configured to emit a beam of light pulses
Implementation Method 2
A suitable detector for ToF-based LiDAR is provided by a single-photon avalanche diode (SPAD) array. SPADs, also known as Geiger-mode avalanche photodiodes (GAPDs), are detectors capable of capturing individual photons with very high time-of-arrival resolution
Implementation Method 3
A beam steering device is configured to transmit and scan the at least one beam across a target scene
Implementation Method 4
Light collection optics are configured to image the target scene scanned by the at least one transmitted beam onto the one or more sensing elements
Data Source
AI summary
An electro-optical device includes a laser light source, which is configured to emit at least one beam of light. A beam steering device is configured to transmit and scan the at least one beam across a target scene. In an array of sensing elements, each sensing element is configured to output a signal indicative of incidence of photons on the sensing element. Light collection optics are configured to image the target scene scanned by the transmitted beam onto the array, wherein the beam steering device scans the at least one beam across the target scene with a spot size and scan resolution that are smaller than a pitch of the sensing elements. Circuitry is coupled to actuate the sensing elements only in a selected region of the array and to sweep the selected region over the array in synchronization with scanning of the at least one beam.