Lidar Light Modulator for Crosstalk and Blinding Prevention
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Solution Overview
Problem
Conventional lidar systems suffer from optical crosstalk and blinding issues due to excessive light reflection, particularly when detecting nearby, highly reflective targets, leading to reduced resolution and measurement errors.
Innovation Solution
A lidar system with a light modulator unit, comprising a Pockels cell and polarizing beam splitter, adjusts the light polarization to maintain a constant light quantity on the detector, preventing crosstalk and blinding, and uses an additional detector for causality checks to differentiate between reflected and external light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser beam power is adjusted to the maximum range of the lidar system, then the detection range is improved, but the detector is excessively irradiated by reflected light from nearby targets, causing optical crosstalk and blooming
Solution Approach 1:
The patent applies a variable attenuator that dynamically adjusts the light transmission based on the detected light quantity. The attenuator transitions from a first attenuation state for strong reflected light (nearby targets) to a second attenuation state for weak reflected light (distant targets), enabling the system to adapt to different ranging distances and prevent optical crosstalk while maintaining detection range.
2Reliability
If the laser beam power is adjusted to the maximum range, then the detection capability is improved, but the detector is blinded by excessive light from nearby highly reflective targets
Solution Approach 1:
The patent employs a feedback mechanism where the detected light quantity is fed back to control the variable attenuator. The controller adjusts the attenuator's transmission based on the detected signal strength, creating a closed-loop system that prevents detector blinding by reducing excessive light transmission while maintaining detection capability for distant targets.
3Device complexity
If conventional lidar systems use fixed attenuation, then the system structure is simple, but the resolution capacity is lost when detecting nearby highly reflective targets
Solution Approach 1:
The patent transitions from fixed attenuation to dynamic attenuation by introducing a variable attenuator controlled by a controller. The attenuator adjusts its transmission state based on real-time detection of light quantity, enabling the system to maintain resolution capacity for nearby targets while keeping the overall system structure relatively simple through automated control.
4Measurement precision
If the lidar system detects nearby targets with high reflectivity, then the measurement accuracy is improved, but the detector receives excessive light energy causing crosstalk and measurement errors
Solution Approach 1:
The variable attenuator dynamically adjusts light transmission based on the detected signal strength from nearby targets. When strong reflected light is detected (indicating nearby highly reflective targets), the attenuator increases attenuation to prevent crosstalk and preserve spatial resolution information, thereby maintaining measurement accuracy without losing resolution data.
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 ensures precise spatial resolution and prevents blinding, allowing for reliable distance measurement and interference rejection, even in the presence of nearby, highly reflective targets or external light sources.
Implementation Method 1
The Pockels cell (4) is designed to rotate a polarization of the laser light continuously between a predefined first polarization and a predefined second polarization
Implementation Method 2
The beam splitter (3) is designed to transmit the laser light onto the detector as a function of the polarization
Implementation Method 3
A laser light source (2) is used to emit a laser light. The laser light passes through the deflecting device (9)
Data Source
AI summary
A lidar system comprising a laser light source for emitting laser light, a light modulator unit, and a detector, the laser light emitted by the laser light source and reflected by an object being directed first through the light modulator unit and thereupon onto the detector, and the light modulator unit being designed to modify over time a light output that strikes the detector.