Interferometric LiDAR Reference Path Switching for Range Control
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Solution Overview
Problem
Conventional optical interferometric LiDAR systems face challenges in accurately measuring absolute positions and relative distances, especially when objects change position or are far away, due to limited coherence length and interference signal intensity reduction by external factors like atmospheric conditions, making it difficult to optimize measurement ranges effectively.
Innovation Solution
An optical interferometric LiDAR system that actively adjusts the reference optical path length using a variable reference arm, allowing for selection of different optical path lengths to maximize optical interference intensity and extend measurement range beyond the coherence length of the light source, even in adverse environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed reference optical path length is used, then the system structure is simple, but the measurement range cannot be optimized for different object positions
Solution Approach 1:
The reference optical path length is made dynamically adjustable through a variable reference arm that can switch between multiple discrete path lengths. This allows the system to adapt to different object positions and measurement requirements, resolving the contradiction between fixed simplicity and adaptive versatility.
Solution Approach 2:
The system changes the reference optical path length parameter actively based on object position and measurement needs. By varying this parameter, the measurement range and signal intensity are optimized for different scenarios, enabling adaptability without requiring complete system redesign.
2Measurement precision
If the reference reflector is positioned for short distance measurement, then near objects are measured accurately, but far objects produce weak conversion signals
Solution Approach 1:
The variable reference arm enables dynamic adjustment of the reference optical path length to match the distance to the target object. This ensures that the optical path difference remains within the coherence length regardless of object distance, maintaining both measurement precision and signal intensity for both near and far objects.
Solution Approach 2:
The system actively changes the reference optical path length parameter based on object distance. For far objects, the reference path is extended to match the measurement arm path length, thereby maintaining strong interference signals while preserving measurement accuracy.
3Length of stationary object
If a laser source with sufficient coherence length is used, then the theoretical measurement range is extended, but absorption and scattering losses reduce the conversion signal intensity
Solution Approach 1:
The system performs preliminary adjustment of the reference optical path length to match the expected measurement distance before actual measurement. This preliminary action ensures that the optical paths are balanced, maximizing interference signal intensity and compensating for absorption and scattering losses over long distances.
Solution Approach 2:
By actively adjusting the reference optical path length parameter to match the measurement arm path length, the system optimizes the interference condition and maximizes signal intensity, thereby compensating for energy losses due to absorption and scattering in the atmosphere.
4Length of stationary object
If the optical path length difference exceeds the coherence length, then the measurement range is extended, but the conversion signal intensity drops below detectable levels
Solution Approach 1:
The variable reference arm provides dynamic adjustment capability, allowing the reference optical path length to be changed based on the target object's distance. This ensures that the optical path difference remains within the coherence length even when measuring far objects, maintaining both extended measurement range and sufficient signal intensity for accurate detection.
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 optimized measurement ranges with enhanced optical interference signal intensity, allowing for accurate measurement of absolute positions and relative distances, even in changing environments, by actively adjusting the reference arm's optical path length based on absorption and scattering losses.
Implementation Method 1
a laser source unit configured to emit light having a variable wavelength
Implementation Method 2
An optical interference signal is generated due to a difference in distance between the respective optical paths
Implementation Method 3
The optical interference signal is output as an electrical signal through the light detection unit
Data Source
AI summary
An optical interferometric LiDAR system to control the main measurement range using active selection of a reference optical path length according to an absolute position of an object to be measured, including: a laser source unit configured to emit light having a variable wavelength; a light dividing unit configured to divide the light into a variable reference arm and a measurement arm; a variable reference arm having a structure for selecting an optical path length of a reference arm; a measurement arm configured to propagate light and receive light reflected from a target object; and a light detecting unit configured to detect an optical signal generated as light passing through the variable reference arm and light passing through the measurement arm cause optical interference.