Lidar Signal-to-Noise Ratio via Optical Spectrum Analyzer
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Solution Overview
Problem
Conventional lidar systems require complex configurations and increased costs due to the need for photodetectors for individual wavelengths, leading to reduced signal-to-noise ratio (SNR) due to wavelength separation and light power attenuation.
Innovation Solution
A lidar system utilizing multiple CW laser light sources with different wavelengths, an optical multiplexing coupler, and an optical fiber amplifier to amplify and modulate the laser light, allowing for high SNR measurement without the need for individual wavelength photodetectors, thereby simplifying the configuration and reducing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple CW laser light sources with different wavelengths are used to increase transmission power, then the signal-to-noise ratio is improved, but the configuration becomes complex and the cost increases due to the need for photodetectors for individual wavelengths
Solution Approach 1:
The patent combines multiple wavelength detection capabilities into a single photodetector by using an optical spectrum analyzer to disperse the light and a single photodetector to detect all wavelengths simultaneously. This merging approach eliminates the need for multiple photodetectors while maintaining the ability to measure multiple wavelengths, thereby improving the signal-to-noise ratio without increasing device complexity or cost.
Solution Approach 2:
The patent introduces an optical spectrum analyzer as an intermediary device between the light source and the photodetector. This intermediary disperses the multiple wavelengths spatially, allowing a single photodetector to sequentially detect different wavelengths. The optical spectrum analyzer acts as a mediator that enables multi-wavelength detection with single-wavelength detection hardware, simplifying the overall system configuration.
2Measurement precision
If the number of signal light wavelengths is increased to improve measurement accuracy, then the signal-to-noise ratio is improved, but the wavelength separation device becomes more complex and causes greater light power attenuation
Solution Approach 1:
The patent extracts the wavelength separation function from the detection path by using an optical spectrum analyzer to disperse the light before detection. Instead of using complex wavelength separation devices in the main optical path, the patent separates wavelengths spatially at the detection stage, minimizing light power attenuation while enabling multi-wavelength measurement accuracy improvement.
3Measurement precision
If photodetectors for individual wavelengths are used to detect scattered light, then the signal-to-noise ratio is improved, but the device size and cost increase
Solution Approach 1:
The patent merges multiple wavelength detection functions into a single photodetector by using an optical spectrum analyzer to spatially disperse the incoming light. The optical spectrum analyzer directs different wavelengths to different positions on the photodetector surface or sequentially focuses them on a single detection point, enabling multi-wavelength detection with a single photodetector component. This significantly reduces device size while maintaining high signal-to-noise ratio measurement capability.
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 high SNR measurement with a simplified configuration, increasing signal strength and reducing noise, enabling highly sensitive and accurate position and velocity measurements of targets.
Implementation Method 1
an optical fiber amplifier that amplifies the laser light modulated by the light modulator
Implementation Method 2
a light modulator that modulates first CW laser light split by the optical branching unit
Implementation Method 3
by detecting the Doppler shift the scattered light undergoes
Implementation Method 4
by emitting laser light into an atmosphere, by receiving scattered light of the laser light by a target
Data Source
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AI summary
A lidar includes CW laser light sources 1 and 2 that oscillate CW laser light rays with wavelengths different from each other; an optical multiplexing coupler 3 that mixes the CW laser light rays oscillated by the CW laser light sources 1 and 2; an optical branching coupler 4 that splits the CW laser light passing through the mixing by the optical multiplexing coupler 3; a light modulator 5 that modulates first CW laser light split by the optical branching coupler 4; and an optical fiber amplifier 6 that amplifies the laser light modulated by the light modulator 5, in which a transmit-receive optical system 8 irradiates a target with the laser light amplified by the optical fiber amplifier 6, and receives scattered light of the laser light by the target.