Integrated CW LiDAR Frequency Modulation Scanning
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Solution Overview
Problem
Current LiDAR systems have limitations in efficiency and scanning speed, which can be improved for real-time and continuous environmental monitoring in scenarios like autonomous vehicles.
Innovation Solution
An on-chip or integrated continuous-wave LiDAR system is developed, utilizing multiple light engines with modulated light beams, balanced detectors, and optical collimating systems to enhance distance calculation precision and scanning efficiency by calculating frequency differences between transmitted and reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If time of flight (TOF) method with laser pulses is used, then distance measurement capability is achieved, but scanning speed and efficiency are limited
Solution Approach 1:
The patent uses periodic modulation of the continuous-wave laser light frequency according to a predefined pattern (e.g., triangular or sinusoidal modulation). This periodic frequency modulation allows the system to encode distance information in the phase of the reflected light, enabling rapid distance measurements without the need for repeated pulse transmissions, thus significantly improving scanning speed and reducing measurement time.
Solution Approach 2:
The patent employs continuous-wave laser illumination instead of pulsed illumination. The continuous light beam is modulated in frequency, allowing for continuous distance measurements to be taken as the laser scans across the scene. This continuous operation eliminates the dead time between pulses, maintaining constant measurement capability and improving overall scanning efficiency and speed.
2Productivity
If frequency modulation is applied to continuous-wave light, then scanning efficiency is improved, but system complexity increases
Solution Approach 1:
The patent replaces mechanical scanning systems with acousto-optic or electro-optic modulators that can rapidly change the frequency of the continuous-wave laser light electronically. This substitution of mechanical frequency-changing mechanisms with electronic/optical modulation devices improves scanning efficiency while the integration of these components into a compact LiDAR system helps manage overall system complexity.
Solution Approach 2:
The patent changes the frequency parameter of the continuous-wave laser light in a predefined modulation pattern. By modulating the light frequency rather than using mechanical movement or complex timing systems, the system achieves improved scanning efficiency. The frequency modulation approach allows for simpler system architecture compared to pulsed TOF methods, as it eliminates the need for precise pulse timing and synchronization mechanisms.
3Measurement precision
If balanced detector is used to detect beat frequency, then distance measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a balanced detector as an intermediary device that mixes the reflected modulated light with a reference local oscillator light beam. This mixing process produces a beat frequency signal that contains the distance information. The balanced detector configuration, which uses two photodetectors with differential output, improves measurement precision by rejecting common-mode noise and DC offsets while maintaining a manageable device complexity through its well-established design in optical detection systems.
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 improved scanning efficiency and performance by calculating distances using frequency differences, enabling real-time and continuous monitoring of environmental features with enhanced resolution and speed.
Implementation Method 1
The balanced detector may be configured to detect a beat between the reflected first portion of the light beam with a second portion of the light beam
Implementation Method 2
The light frequency is modulated in a predefined pattern
Implementation Method 3
Individual points are measured by generating a laser pulse and detecting a returning pulse reflected from a surface of an environmental object
Data Source
AI summary
Aspects for an on-chip or integrated continuous-wave Light Detection and Ranging (LiDAR) are described herein. The aspects may include one or more laser light sources configured to generate one or more light beams and multiple light engines configured to respectively receive the light beams. The light frequency is modulated in a predefined pattern. A light transmitter of each light engine may be configured to receive a first portion of one of the light beams and transmit the first portion of the light beam at a predetermined angle. A light receiver of each light engine may be configured to receive the first portion of the light beam reflected from an object and transmit the reflected first portion of the light beam to a balanced detector. The balanced detector may be configured to detect a beat between the reflected first portion of the light beam with a second portion of the light beam.