Lidar Retro-Reflection Suppression via Phase-Controlled Destructive Interference
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Solution Overview
Problem
Lidar devices face significant challenges due to spurious retro-reflections, which can overpower target reflections and degrade the accuracy of distance and velocity measurements, particularly in applications like autonomous vehicle navigation where precision is critical.
Innovation Solution
The implementation of a lidar system that generates a phase-controlled beam to interfere destructively with retro-reflected light, using techniques such as amplitude changers and phase shifters to combine the phase-controlled beam with the received beam, thereby suppressing retro-reflections and enhancing the detection of target-reflected beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional lidar devices emit transmitted beams to detect objects, then distance and velocity measurements can be obtained, but spurious retro-reflections from internal components overpower target reflections and degrade measurement accuracy
Solution Approach 1:
The patent generates a control beam that replicates the retro-reflection path and uses destructive interference to cancel the spurious retro-reflections. By converting the harmful retro-reflection phenomenon into a controllable interference pattern, the system eliminates the harmful effect while preserving the useful target reflection signals for accurate distance and velocity measurements
Solution Approach 2:
The system preemptively generates a control beam with predetermined amplitude and phase characteristics that are designed to destructively interfere with the expected retro-reflections. This preliminary anti-action occurs before the retro-reflections can overpower the target signals, preventing measurement accuracy degradation from the outset
2Measurement precision
If phase-controlled beams are generated and combined with received beams to suppress retro-reflections, then measurement accuracy improves, but device complexity increases due to additional optical components
Solution Approach 1:
The patent employs optical components such as beam combiners and phase modulators that serve multiple functions: they combine the control beam with the received beam, manipulate phase relationships for destructive interference, and maintain signal integrity for detection. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving retro-reflection suppression
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 significantly improves the efficiency and accuracy of lidar systems by reducing spurious retro-reflections, leading to enhanced safety and performance in autonomous vehicle driving missions by ensuring more precise distance and velocity measurements.
Implementation Method 1
controlling a phase of the phase-controlled beam to cause at least partial destructive interference of the phase-controlled beam and the first RR beam
Data Source
AI summary
The subject matter of this specification can be implemented in, among other things, systems and methods of optical sensing that use destructive interference to suppress retro-reflected light during generation of sensing beams. Described, among other things, is a system to produce a transmitted (TX) beam and collect a received (RX) beam. The RX beam can include a reflected beam caused by interaction of the TX beam with an object, and a retro-reflected (RR) beam caused by interaction of the TX beam internal components of the system. The system is further to combine the RX beam with a phase-controlled beam to obtain a combined beam, control a phase of the phase-controlled beam to cause destructive interference of the phase-controlled beam and the RR beam, and determine, using the combined beam, one or more of the characteristics of the object.