Multi-wavelength Array Lidar Wavelength-Angle Compensation
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Solution Overview
Problem
Current array lidar systems face challenges in receiving reflections at the same wavelength due to the angle-wavelength dependence of band pass filters, leading to a trade-off between minimizing sunlight interference and capturing all reflections, resulting in suboptimal signal-to-noise ratio.
Innovation Solution
The system arranges lasers to transmit beams at specific angles and corresponding wavelengths, ensuring that received reflections are within a narrower wavelength range, allowing for a narrower band pass filter to reduce sunlight interference while capturing all reflections, using equations to determine optimal transmission wavelengths based on incident angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a band pass filter is used to filter reflections in a conventional array lidar system, then sunlight interference is reduced, but reflections at different incident angles are not passed at the same wavelength due to angle-wavelength dependence
Solution Approach 1:
The patent changes the wavelength parameter of transmitted beams based on their incident angle. Each beam is assigned a specific wavelength from a multi-wavelength set that corresponds to its angle of incidence. This ensures that after reflection and passing through the band pass filter, all reflections converge to the same receive wavelength, resolving the angle-wavelength dependence issue while maintaining effective sunlight filtering.
Solution Approach 2:
The patent segments the laser array into multiple wavelength channels, where each laser element operates at a distinct wavelength. This segmentation allows different angular beams to be assigned different transmit wavelengths that compensate for their angle of incidence, ensuring uniform receive wavelength filtering through the band pass filter.
2Ease of operation
If all lasers transmit at the same wavelength, then the system is simpler to operate, but the band pass filter cannot effectively capture all reflections at different angles
Solution Approach 1:
The system transitions from a single-wavelength operation to multi-wavelength operation, where each laser element in the array operates at a specifically assigned wavelength. This parameter change enables the band pass filter to effectively capture reflections from all angles by compensating for angle-wavelength dependence, while the systematic wavelength assignment maintains operational simplicity.
3Reliability
If a wide band pass filter is used to capture all reflections, then all incident angles are received, but sunlight interference increases reducing signal-to-noise ratio
Solution Approach 1:
The patent employs a narrow band pass filter centered at a specific receive wavelength by assigning different transmit wavelengths to beams at different incident angles. This wavelength parameter assignment ensures that all reflections, regardless of incident angle, are converted to the same receive wavelength, enabling effective sunlight rejection while maintaining complete reflection capture.
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 enables the use of a narrow band pass filter to improve signal-to-noise ratio by filtering out sunlight while ensuring all reflections are captured within a narrow wavelength range, facilitating the use of more sensitive avalanche detectors.
Implementation Method 1
arranging a band pass filter to filter a plurality of reflections received at a respective plurality of incident angles
Implementation Method 2
arranging a lens to disperse the plurality of beams at a respective plurality of angles
Implementation Method 3
a plurality of lasers arranged in an array, the plurality of lasers configured to transmit a respective plurality of beams at a respective plurality of transmit angles and respective transmit wavelengths
Data Source
AI summary
A multi-wavelength array lidar system and a method of designing an array lidar system include arranging a plurality of lasers in an array to transmit a respective plurality of beams, arranging a lens to disperse the plurality of beams at a respective plurality of angles, and arranging a band pass filter to filter a plurality of reflections received at a respective plurality of incident angles resulting from the plurality of beams transmitted by the plurality of lasers at a respective plurality of transmit angles. Selecting a transmit wavelength of each of the plurality of beams is based on the respective plurality of transmit angles to ensure that a receive wavelength of each of the plurality of reflections is within a narrower range than a range of the transmit wavelengths.