Differential Mode Laser Detection Attenuating Atmospheric Turbulence
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Solution Overview
Problem
Laser detection and ranging devices face challenges in accurately measuring target vibrations due to noise sources like atmospheric turbulence and piston mode vibrations, which limit the quality of information obtained.
Innovation Solution
A system comprising multiple spatially separated detectors coupled to a differential signal analyzer, which generates a coherent light beam and applies phase shifts to combine signals to form differential signals representative of physical vibrations, effectively attenuating noise sources and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional laser detection and ranging devices use a single detector to measure target vibrations, then the device complexity is low, but the measurement precision is degraded due to noise from atmospheric turbulence and piston mode vibrations
Solution Approach 1:
The system divides the detection function into multiple spatially separated detectors (at least two detectors positioned at different locations) that independently measure vibration components. This segmentation allows the system to separate useful vibration signals from common-mode noise by comparing measurements from different spatial positions, thereby improving measurement precision without requiring a single complex detector.
Solution Approach 2:
The system merges the outputs of multiple detectors through a signal processor that combines signals from at least two detectors. By merging these signals and applying differential processing, the system eliminates common-mode noise (atmospheric turbulence and piston mode vibrations) while preserving target vibration information, achieving high measurement precision through combined data from multiple simpler detectors.
2Measurement precision
If the system uses multiple spatially separated detectors to improve measurement precision, then the noise floor is reduced, but the device complexity increases
Solution Approach 1:
The signal processor automatically performs differential processing by itself without requiring external intervention. The system self-calibrates and self-corrects for common-mode noise by comparing detector outputs and applying phase shifts, eliminating the need for complex manual calibration procedures or additional external equipment, thus managing the complexity internally while maintaining high precision.
Solution Approach 2:
The system changes the parameter of phase shift application to the detector signals. By introducing controlled phase shifts (e.g., 180 degrees) between signals from different detectors before combining them, the system transforms common-mode noise into differential signals that can be rejected, thereby reducing the noise floor and improving measurement precision through parameter manipulation rather than complex hardware.
3Object-affected harmful factors
If conventional systems do not use differential mode processing, then the device complexity is low, but harmful factors like atmospheric turbulence and piston mode vibrations cannot be attenuated
Solution Approach 1:
The system converts the harmful common-mode noise (atmospheric turbulence and piston mode vibrations) into a beneficial feature by using it for differential processing. By applying phase shifts and combining detector signals, the system makes the noise common-mode and rejects it differentially, transforming what was previously a detrimental factor into a mechanism for noise cancellation and improving overall measurement quality.
Solution Approach 2:
The signal processor continuously monitors and processes the outputs from multiple detectors, using feedback from the detector array to dynamically adjust signal combining operations. This feedback mechanism allows the system to adapt to varying noise conditions and maintain optimal noise attenuation, effectively managing harmful factors through continuous differential processing without requiring complex pre-programmed compensation schemes.
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 improves measurement accuracy by mitigating noise sources, allowing for the detection of higher order vibration modes and reducing noise floor, thereby enhancing the operational effectiveness of laser detection and ranging devices.
Implementation Method 1
The light source generates a coherent light beam onto a target that is reflected as backscattered light
Implementation Method 2
The differential signal analyzer then applies a phase shift to a subset of the received signals and combines the phase shifted signals with signals from other detectors
Data Source
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AI summary
According to one embodiment, a system for measuring vibration includes multiple spatially separated detectors coupled to a differential signal analyzer and a light source. The light source generates a coherent light beam onto a target that is reflected as backscattered light. The differential signal analyzer receives signals from each of the detectors indicative of backscattered light from the target. The differential signal analyzer then applies a phase shift to a subset of the received signals and combines the phase shifted signals with signals from other detectors to form a differential signal representative of physical vibration of the target.