Coherent Pulsed Lidar Two-Sided Detector
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Solution Overview
Problem
Current lidar systems face challenges in efficiently determining distances to targets with low reflectivity due to the small fraction of returned light, which affects accuracy and range resolution.
Innovation Solution
The lidar system employs a light source with a semiconductor optical amplifier and a local-oscillator laser to emit pulses of light, combined with a receiver that coherently mixes the returned light with local-oscillator light to enhance detection sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lidar detection methods are used, then the system can detect targets with sufficient reflectivity, but the detection sensitivity is insufficient for low-reflectivity targets
Solution Approach 1:
The patent introduces local-oscillator light as an intermediary to enhance the detection of weak return signals. The local-oscillator light mixes with the returned light from low-reflectivity targets through coherent detection, amplifying the weak signal and enabling sensitive detection that would otherwise be impossible with conventional direct detection methods
Solution Approach 2:
The patent changes the detection parameter from direct intensity measurement to coherent mixing with local-oscillator light. By converting the detection mechanism to measure the interference pattern between return light and local-oscillator light, the system achieves enhanced sensitivity for detecting low-reflectivity targets
2Measurement precision
If the fraction of returned light is small, then the target has low reflectivity, but this reduces the accuracy and range resolution
Solution Approach 1:
The local-oscillator light serves as a mediator that enables the system to extract meaningful information from the small fraction of returned light. Through coherent mixing, the weak return signal is amplified, allowing accurate range resolution even when the quantity of returned light is minimal
Solution Approach 2:
The system performs preliminary action by generating local-oscillator light before the detection process. This pre-prepared local-oscillator light is ready to mix with the returning signal, enabling enhanced detection and range resolution without requiring a large fraction of light to be reflected from the target
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 significantly improves the detection of low-reflectivity targets by increasing the sensitivity of the receiver, allowing for more accurate distance measurements and better range resolution.
Implementation Method 1
a receiver that coherently mixes the returned light with local-oscillator light to enhance detection sensitivity and accuracy
Data Source
AI summary
In one embodiment, a lidar system includes a light source configured to emit (i) local-oscillator light and (ii) pulses of light. The lidar system also includes a receiver configured to detect the local-oscillator light and a received pulse of light, the received pulse of light including a portion of one of the emitted pulses of light scattered by a target located a distance from the lidar system. The receiver includes a detector configured to produce a photocurrent signal corresponding to a coherent mixing of the local-oscillator light and the received pulse of light. The detector includes a first input side and a second input side located opposite the first input side, where the received pulse of light is incident on the first input side of the detector, and the local-oscillator light is incident on the second input side of the detector.