Lidar Humidity Compensation via Absorption Coefficient Correction
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Solution Overview
Problem
Lidar systems face challenges in accurately determining the distance to targets due to the low power return signal from scattered light, which is affected by factors such as humidity, leading to errors in optical characteristic measurements.
Innovation Solution
A lidar system that includes a light source emitting a beam with adjustable wavelength, coupled with a humidity sensor to determine the optical absorption coefficient, allowing for correction of signal attenuation and improved distance measurement accuracy by compensating for humidity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional lidar systems measure distance based on time of flight without humidity compensation, then the system structure remains simple, but measurement precision deteriorates due to humidity-induced signal attenuation
Solution Approach 1:
A humidity sensor is introduced as an intermediary device to measure environmental humidity, which then feeds into a controller that calculates compensation values based on optical absorption coefficients. This intermediary measurement system allows the lidar to correct for atmospheric effects without fundamentally changing its core time-of-flight measurement mechanism, thus improving precision while adding only moderate complexity.
Solution Approach 2:
The system performs preliminary measurement of humidity conditions before the optical signal traverses the atmosphere. By measuring humidity in advance and using it to calculate expected signal attenuation, the system can compensate for atmospheric effects proactively rather than attempting to correct them after the fact, improving measurement accuracy with minimal additional complexity.
2Reliability
If lidar systems operate in humid environments without compensation, then device complexity remains low, but reliability of measurements deteriorates due to signal loss
Solution Approach 1:
The system implements a feedback mechanism where humidity sensor data continuously informs the measurement process. The controller uses real-time humidity readings to dynamically adjust compensation calculations, creating a closed-loop system that adapts to changing atmospheric conditions. This feedback approach ensures reliable measurements across varying humidity levels while maintaining a relatively simple system architecture.
Solution Approach 2:
The system changes the operational parameters by incorporating humidity as an additional measurement parameter. By measuring humidity and using it to determine optical absorption coefficients, the system adapts its measurement process to environmental conditions. This parameter-based adaptation improves reliability without requiring complex hardware modifications to the core lidar system.
3Measurement precision
If humidity compensation is implemented using absorption coefficients, then measurement accuracy improves, but loss of information increases due to additional correction calculations
Solution Approach 1:
The system converts the harmful effect of humidity-induced signal attenuation into a beneficial correction process. By measuring humidity and calculating the corresponding absorption coefficients, the system quantifies the signal loss and applies mathematical compensation to recover the true target reflectivity. This approach transforms an unavoidable physical phenomenon into a correctable parameter, improving optical characteristic accuracy while accounting for the information loss through systematic correction.
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 enhances the accuracy of distance measurements by accounting for humidity-induced signal loss, providing precise optical characteristic values and target reflectivity, thereby improving the overall performance of lidar systems in various environmental conditions.
Implementation Method 1
The light source emits light toward a target which scatters the light, and some of the scattered light is received back at the receiver
Implementation Method 2
determine the optical absorption coefficient... compensating for humidity effects... humidity-induced signal loss
Data Source
AI summary
In one embodiment, a lidar system includes a light source configured to emit an optical signal that is directed into a field of regard (FOR) of the lidar system. The lidar system also includes a receiver configured to: receive a portion of the emitted optical signal scattered by a target located in the FOR a distance from the lidar system; and produce an electrical signal corresponding to the received optical signal, where the electrical signal is related to a preliminary value of an optical characteristic of the received optical signal. The lidar system further includes a processor coupled to the receiver and configured to: determine the distance to the target; receive a humidity value; and determine a corrected value of the optical characteristic of the received optical signal based at least in part on the electrical signal produced by the receiver, the distance to the target, and the humidity value.