Synthetic Wave Laser Ranging Using Multi-Laser Interference
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Solution Overview
Problem
Existing laser ranging sensors face challenges in achieving high-precision distance measurements, particularly in the assembly of large objects where precise matching of shapes and contours is required, and existing solutions do not provide sufficient accuracy or reliability across different environments and locations.
Innovation Solution
The system employs a combination of multiple continuous-wave lasers to generate a ladder of synthetic waves through interference, with frequency-shifted local oscillator beams used to determine optical phases, allowing for precise distance calculations. This setup includes a frequency comb laser for calibration, ensuring measurements are traceable to a standard frequency, enhancing accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple continuous-wave lasers are used to generate synthetic waves, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system segments the measurement function by using multiple continuous-wave lasers operating at different frequencies to generate multiple synthetic waves. Each laser-synthetic wave combination provides an independent measurement channel, and the results are combined to achieve high-precision distance measurement. This segmentation allows the system to overcome the limitations of single-wavelength systems while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The patent introduces synthetic waves as an intermediary mechanism that bridges the gap between multiple laser sources and the final distance measurement. By mixing light beams from multiple lasers to create synthetic waves with extended wavelengths, the system translates complex multi-frequency interference patterns into measurable signals that provide precise distance information without requiring direct comparison of all laser frequencies.
2Reliability
If frequency comb laser calibration is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary calibration using a frequency comb laser before actual distance measurements are taken. The frequency comb provides a known reference spectrum that allows precise determination of the absolute frequencies of the continuous-wave lasers. This preliminary frequency establishment ensures that all subsequent synthetic wave measurements are based on accurately known laser frequencies, guaranteeing measurement consistency and traceability to frequency standards.
3Measurement precision
If heterodyne detection is used to determine optical phases, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system employs heterodyne detection where local oscillator beams are frequency-shifted relative to the signal beams, creating beat frequencies that manifest as oscillating interference patterns. These oscillations at known frequency offsets allow precise determination of optical phases by measuring the amplitude and phase of the heterodyne signals. The frequency shifting introduces a controlled temporal variation that transforms static optical phase information into dynamic, easily measurable electrical signals.
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 solution provides highly accurate and reliable distance measurements, capable of precise assembly of large objects by generating a ladder of synthetic waves, which increases measurement accuracy and ensures consistency across different environments and locations.
Implementation Method 1
When the light beams are mixed in the interference beams, the light beams of different frequencies will generate 'beat' frequencies referred to herein as 'synthetic waves'
Implementation Method 2
a portion of the light beams from the continuous-wave lasers are split off and frequency shifted to generate local oscillator beams
Implementation Method 3
A photodetector device is configured to sense the synthetic wave beam to generate output signals
Data Source
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AI summary
Systems and methods for measuring a distance to an object. An exemplary method includes directing light beams from three or more continuous-wave lasers onto a target to generate an interference beam, and also frequency shifting the light beams split off from the lasers to generate local oscillator beams. When the interference beam and the local oscillator beams are combined, the method further includes determining optical phases of heterodynes produced by combining the light beams and the local oscillator beams, and determining synthetic phases by taking the difference between the optical phases of the heterodynes. The method further includes determining synthetic wavelengths based on the differences between the frequencies of the lasers. The method further includes determining a distance to the target based on the synthetic phases and the synthetic wavelengths.