CBC Laser Range-Finding with Phase Modulation Correction
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Solution Overview
Problem
Prior art laser range-finding systems fail to achieve a suitable combination of laser power, intensity modulation bandwidth, and laser coherence length, which are insufficient for meeting stringent requirements of target range, time-of-flight measurement accuracy, and update rate, especially in directed energy applications.
Innovation Solution
A range-finding apparatus and method utilizing optical phase modulation of partially coherent laser sub-beams in a coherent beam combining (CBC) system, with a phase modulation controller and signal processor to calculate frequency components, rotate them for time-of-flight correction, and determine a corrected measurement of target range with reduced uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional laser range-finding methods are used, then measurement capability is provided, but the system requires complex calibration procedures and is sensitive to environmental conditions
Solution Approach 1:
The system performs self-calibration by automatically determining calibration parameters through multiple measurements at different known distances. The processor calculates calibration parameters based on the relationship between drive signal frequencies and measured distances, eliminating the need for manual calibration procedures while maintaining measurement accuracy across varying environmental conditions.
2Measurement precision
If conventional laser range-finding methods are used, then measurement capability is provided, but the system performance varies with environmental conditions such as temperature and humidity
Solution Approach 1:
The system compensates for environmental variations by dynamically adjusting calibration parameters based on temperature and humidity sensor readings. The processor modifies the frequency-to-distance conversion parameters in real-time according to environmental conditions, ensuring consistent measurement accuracy across different operating environments without requiring manual recalibration.
3Measurement precision
If multiple measurements are taken to improve accuracy, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The system performs preliminary calibration measurements at different known distances to establish the relationship between drive signal frequencies and actual distances. This preliminary action creates a calibration model that can be quickly applied during subsequent range-finding operations, enabling accurate measurements without requiring multiple time-consuming measurements for each reading.
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 method achieves high time-of-flight measurement accuracy and update rate, improving uncertainty by a factor of at least 300, even in the presence of electronic noise, using partially coherent sub-beams with coherence lengths less than one meter.
Implementation Method 1
the laser is configured to measure a distance to a target object
Implementation Method 2
the laser comprises a light source, a transmitter optical sub-assemble (TOSA), a receiver optical sub-assemble (ROSA) and a photodetector
Data Source
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AI summary
A range-finding apparatus and method for measuring the range of a target illuminated by a coherent beam combining (CBC) system having at least two partially coherent sub-beams. The apparatus includes a phase modulation controller and a signal processor. The controller provides one or more optical phase modulation signals to the CBC system. The signal processor receives an initial measurement of target range, provided by either the CBC system or an external range-finding device and having a relatively large uncertainty, and a time-varying received intensity signal provided by the CBC system. The signal processor calculates frequency components of the intensity signal, forms rotated frequency components corresponding to a time-of-flight correction, calculates an objective function depending upon the rotated frequency components, determines a global minimum of the objective function, and calculates a corrected measurement of target range having an uncertainty which is less than that of the initial measurement of target range.