Solid-State LiDAR Adaptive Shutter for Long-Range Noise Control
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Solution Overview
Problem
Autonomous vehicles require LIDAR systems with improved signal-to-noise ratio (SNR) to detect objects at longer ranges, especially in automotive applications, while adhering to Class 1 eye safety standards and maintaining reliability with no moving parts, and the ability to adapt to changing environments and measurement requirements.
Innovation Solution
A noise-adaptive solid-state LIDAR system that employs an adaptive optical shutter or mirror to control the field-of-view, reducing ambient light interference and optimizing the number of detectors and lasers to enhance SNR, and incorporates a processor to adjust the illumination pattern and pulse averaging for improved measurement resolution and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser power is increased to improve measurement range, then the detection capability is improved, but the eye safety requirement is violated
Solution Approach 1:
The system uses pulsed laser operation instead of continuous wave, transmitting laser energy in short bursts. This allows the peak power to be high enough for detection while the average power remains low enough to satisfy eye safety requirements. The pulse width is controlled to be less than the human eye response time.
Solution Approach 2:
The system dynamically adjusts the laser power and pulse characteristics based on environmental conditions, target distance, and noise levels. The controller modifies transmission parameters in real-time to achieve optimal detection while maintaining safety margins.
2Area of stationary object
If the field-of-view is increased to improve coverage, then the detection area is improved, but the signal-to-noise ratio deteriorates due to increased ambient light interference
Solution Approach 1:
The system employs an adaptive optical shutter that dynamically adjusts the field-of-view aperture based on environmental conditions and measurement requirements. When ambient light is high, the shutter closes to reduce the field-of-view and minimize noise. When ambient light is low or for long-range detection, the shutter opens to maximize the field-of-view for coverage.
Solution Approach 2:
The system changes the effective field-of-view parameter dynamically by controlling the optical shutter position, allowing optimization of the trade-off between coverage area and signal-to-noise ratio based on real-time conditions.
3Measurement precision
If the number of detectors is increased to improve resolution, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The system uses time-sequential activation of detector elements rather than requiring all detectors to be active simultaneously. By pulsing individual detectors or detector groups in sequence and using the adaptive shutter to block light during transitions, the system achieves high-resolution scanning with fewer physical detectors.
Solution Approach 2:
The system dynamically configures which detector elements are active based on the current measurement requirements, using electronic control to enable or disable specific detector regions, thereby reducing the effective number of detectors needed at any given time.
4Measurement precision
If the pulse width is increased to improve signal strength, then the signal-to-noise ratio is improved, but the time resolution deteriorates
Solution Approach 1:
The system uses very short laser pulses with widths less than the human eye response time, repeating these pulses at high frequency. This allows accumulation of signal strength through multiple pulses while maintaining excellent time resolution for each individual pulse measurement.
Solution Approach 2:
The system performs continuous measurements using repeated pulse sequences, accumulating data over time to improve signal strength while maintaining the temporal resolution of individual pulses through consistent timing references.
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 longer measurement ranges, improved reliability, and adaptability, enabling effective detection of fast-moving objects while maintaining eye safety and reducing noise interference, thus enhancing the performance of LIDAR systems in automotive applications.
Implementation Method 1
an optical transmitter configured to generate a plurality of laser beams in a pulsed fashion
Implementation Method 2
a time-of-flight measurement circuit determines a time-of-flight for light from the plurality of lasers to the plurality of detectors
Implementation Method 3
an adaptive optical shutter or mirror to control the field-of-view, reducing ambient light interference
Implementation Method 4
a plurality of detectors positioned to detect light over the illumination region
Data Source
AI summary
A LIDAR system includes an optical transmitter comprising a plurality of lasers, each illuminating a FOV in an illumination region. A transmitter controller has outputs connected to respective laser inputs. The transmitter controller generates electrical pulses at the outputs so that the lasers generate light in a desired pattern in the illumination region. An optical receiver has an input FOV in the illumination region and comprises a plurality of detectors, each having a FOV and being positioned to detect light over the illumination region; and a TOF measurement circuit that measures the TOF from the lasers to the detectors. The receiver calculates range information. An adaptive optical shutter positioned between the optical transmitter and the optical receiver has a transparent or reflected region FOV, where the optical shutter restricts illumination at the input of the optical receiver to a region which is smaller than the optical receiver FOV.