Optical Phased Array Lobe Alignment for LiDAR False Detection Control
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Solution Overview
Problem
Optical phased array (OPA) LiDAR systems produce spurious signal peaks due to side and grating lobes, which can exceed the noise floor and cause false detection events, especially in environments with retroreflectors.
Innovation Solution
Implementing a method where the spacings and phase shifts of a first and second OPA are configured to align or misalign main and grating lobes, allowing for selective scanning and detection threshold adjustments to mitigate spurious signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If optical phased array LiDAR systems use standard radiation patterns with side lobes and grating lobes, then the scanning coverage is expanded, but spurious signal peaks are generated that cause false detection events
Solution Approach 1:
The patent applies asymmetry by using different antenna spacings in the transmitting and receiving OPAs. The transmitting OPA has a first spacing that produces grating lobes at specific angles, while the receiving OPA has a second spacing that shifts its grating lobes to different angles. This asymmetric configuration ensures that when the transmitting OPA illuminates a region, the receiving OPA does not have grating lobes aligned with the reflected signals from that region, thereby suppressing spurious peaks while maintaining scanning coverage
Solution Approach 2:
The patent changes the physical parameter of antenna spacing between the transmitting and receiving OPAs. By selecting specific spacing values for each OPA, the grating lobe angles are controlled and differentiated. This parameter change allows the system to maintain the necessary scanning coverage while shifting the harmful grating lobes to angles where they do not interfere with the main detection lobes, thus reducing false detections
2Productivity
If the intensity of spurious signals from grating lobes and side lobes exceeds the noise floor, then more of the region can be scanned, but false detection events increase
Solution Approach 1:
The asymmetric spacing configuration between transmitting and receiving OPAs creates a mismatch in grating lobe positions. This ensures that strong reflected signals from regions scanned by the transmitting OPA do not coincide with the grating lobe directions of the receiving OPA, thereby suppressing spurious signal intensity below the noise floor and preventing false detections while maintaining efficient scanning
Solution Approach 2:
The patent converts the potentially harmful grating lobes into a beneficial configuration. By deliberately designing the receiving OPA with different spacing, the grating lobes are positioned to receive signals from regions that are NOT being actively scanned by the transmitting OPA. This transforms what would be harmful spurious peaks into harmless or useful signals from unscanned regions, thereby maintaining high scanning efficiency without compromising detection accuracy
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
Reduces false detection events by attenuating spurious signals, expanding the scanning range, and enabling accurate detection of objects within the main and grating lobe ranges.
Implementation Method 1
a first optical phased array (OPA) comprising: a plurality of optical antennas separated by a first set of spacings
Implementation Method 2
phases of light provided to respective optical antennas are controlled to form a transmitted beam from the first OPA, the beam characterized by a first angular intensity distribution
Data Source
AI summary
Light is provided to optical antennas (OAs) separated by a first set of spacings in a first OPA. Phases of light provided to respective OAs are controlled to form a transmitted beam whose angle is steered so that first and second lobes of a first angular intensity distribution (AID) scan over first and second portions of a region, respectively. Light is received from OAs separated by a second set of spacings in a second OPA into which light is received from directions associated with a second AID. The first lobe of the first AID and a first lobe of the second AID substantially overlap in angle during the scan of the first lobes, and the second lobe of the first AID and a second lobe of the second AID substantially overlap in angle during the scan of the second lobes.