Laser Pulse Sampling Circuit for LiDAR Peak Power Stability
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Solution Overview
Problem
Current Direct-Time-of-Flight (DTOF) LiDAR and 3D imaging technologies face challenges in precisely controlling the peak power and full width at half-maximum (FWHM) of laser pulses due to Process-Voltage-Temperature (PVT) changes, which affect the accuracy and stability of distance sensing.
Innovation Solution
A high-speed laser pulse sampling and detecting circuit that includes a laser driver, photoelectric converter, linear transimpedance amplifier, low-speed ADC, peak power/FWHM detector, and multi-phase clock generator, which generates a sampling clock signal with a changing phase to accurately sample and detect the peak power and FWHM of laser pulses, allowing for adjustments to maintain stability despite temperature, process, and power supply changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the peak power of laser pulses is increased to achieve longer detection distance, then the detection distance is improved, but the precision of sampling and detecting becomes more difficult due to the very narrow FWHM
Solution Approach 1:
The patent implements a dynamic phase adjustment mechanism for the sampling clock signal. The phase of the sampling clock signal is continuously adjusted based on the detected FWHM of laser pulses. This dynamic adaptation allows the sampling system to maintain optimal precision despite variations in pulse width caused by different peak powers or environmental conditions, thereby resolving the contradiction between extended detection distance and maintained measurement precision
Solution Approach 2:
The patent employs a feedback loop where the detected FWHM information is used to adjust the phase of the sampling clock signal. This closed-loop control ensures that the sampling timing remains synchronized with the laser pulse characteristics, maintaining high measurement precision even when operating at high peak powers with narrow FWHM for extended detection distances
2Stability of the object's composition
If automatic adjustment of peak power and FWHM is implemented to maintain stable output, then the stability of laser pulse parameters is improved, but the complexity of the control system increases
Solution Approach 1:
The patent implements a self-service control mechanism where the system automatically detects its own output parameters (peak power and FWHM) and adjusts them without external intervention. The detection results feed back to the laser driver to automatically correct deviations, eliminating the need for complex external control systems while maintaining stable laser pulse parameters
Solution Approach 2:
The sampling clock signal generation circuit serves multiple functions: it provides the sampling clock for ADC conversion, generates delay signals for FWHM measurement, and enables phase adjustment for optimization. This multi-functionality reduces the need for separate dedicated circuits, thereby controlling system complexity while achieving stable peak power and FWHM through automatic adjustment
3Manufacturing precision
If the FWHM of laser pulses is reduced to improve resolution, then the ranging resolution is improved, but the difficulty of precise sampling and detecting increases due to the very narrow pulse width
Solution Approach 1:
The patent implements a dynamic phase adjustment mechanism for the sampling clock signal. The phase of the sampling clock signal is continuously adjusted based on the detected FWHM of laser pulses. This dynamic adaptation allows the sampling system to maintain optimal precision despite variations in pulse width caused by different peak powers or environmental conditions, thereby resolving the contradiction between extended detection distance and maintained measurement precision
Solution Approach 2:
The system performs preliminary detection of the laser pulse FWHM before conducting precise sampling. By first measuring the pulse characteristics and then adjusting the sampling clock phase accordingly, the system prepares the optimal sampling conditions in advance, making it feasible to accurately sample very narrow pulses with reduced FWHM for improved ranging resolution
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 solution enables precise sampling and detection of high-speed laser pulses, ensuring that peak power and FWHM remain consistent, thereby enhancing the precision and stability of LiDAR/3D sensing systems for applications like autopilot and machine vision.
Implementation Method 1
a photoelectric converter for converting the laser pulse signal into current pulse signal
Data Source
AI summary
A laser pulse sampling and detecting circuit includes: a laser driver which is driven by a triggering signal for generating laser pulse signal; a photoelectric converter for converting the laser pulse signal into current pulse signal; an amplifier for amplifying and converting the current pulse signal into voltage pulse signal; an ADC which is driven by a sampling clock signal for sampling the voltage pulse signal and performing analog-to-digital conversion on the voltage pulse signal, so as to obtain output signal of the ADC; a detector for detecting the output signal of the ADC, so as to obtain peak power and FWHM of the laser pulse signal; and a clock generator for generating the sampling clock signal. Phase of the sampling clock signal consecutively changes with respect to the triggering signal.