Frequency-Modulated Laser Distance Measurement Without Temperature Stabilization
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Solution Overview
Problem
Optical distance meters using frequency-shifted feedback lasers face reduced measurement accuracy due to environmental fluctuations, such as temperature changes, which can increase the apparatus size and cost when attempts are made to mitigate these fluctuations.
Innovation Solution
A measurement apparatus that includes a laser resonator outputting a frequency-modulated laser beam, branching it into reference and measurement lights, generating a beat signal, extracting the resonator frequency component, and calculating the propagation distance difference using a clock signal, allowing for accurate distance measurement while monitoring and compensating for environmental fluctuations without the need for extensive temperature stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If environmental fluctuations are reduced by installing the FSFL in a constant-temperature chamber, then measurement accuracy is improved, but apparatus scale and cost increase
Solution Approach 1:
The patent extracts the resonator frequency information from the frequency-modulated laser beam using a spectral analysis unit. By separating and analyzing the frequency components to identify the resonator frequency, the system can monitor environmental effects without requiring the entire apparatus to be temperature-stabilized, thus maintaining accuracy without increasing apparatus scale.
Solution Approach 2:
The patent uses the extracted resonator frequency as a reference to generate a clock signal that compensates for environmental fluctuations. The system continuously monitors the resonator frequency changes and adjusts the measurement calculations accordingly, creating a feedback mechanism that maintains measurement accuracy without requiring constant-temperature chambers.
2Measurement precision
If environmental fluctuations are reduced by installing the FSFL in a constant-temperature chamber, then measurement accuracy is improved, but cost increases
Solution Approach 1:
The patent extracts only the necessary resonator frequency information from the laser beam using spectral analysis, rather than requiring expensive temperature stabilization systems. This selective extraction approach maintains measurement accuracy while avoiding the high costs associated with constant-temperature chambers.
Solution Approach 2:
The system uses the laser's own resonator frequency as a reference for compensation. By monitoring the resonator frequency changes caused by environmental fluctuations and using this information to adjust measurements, the system performs self-compensation without requiring external temperature control infrastructure, thereby reducing cost.
3Measurement precision
If the resonator length change is monitored by observing FSFL outputs, then measurement accuracy is maintained, but device complexity increases
Solution Approach 1:
The frequency analysis unit serves multiple functions: it characterizes the laser output, extracts the resonator frequency, and provides reference information for compensation. By making this single unit multi-functional, the patent maintains measurement accuracy without adding separate monitoring devices, thus avoiding increased device complexity.
Solution Approach 2:
The patent extracts the resonator frequency information from the existing laser beam using spectral analysis, rather than requiring separate monitoring apparatus. This extraction approach allows the system to track resonator length changes while using the same optical path, avoiding additional complex monitoring equipment.
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 solution enables accurate distance measurement with a simple configuration, suppressing the reduction in measurement accuracy caused by environmental fluctuations without increasing the apparatus size or cost, thereby maintaining precision without the need for a thermostatic chamber.
Implementation Method 1
a laser apparatus that has a laser resonator and outputs a frequency-modulated laser beam with a plurality of modes
Implementation Method 2
a beat signal generation part that generates a beat signal by mixing the reference light and a reflected light
Data Source
AI summary
A measurement apparatus that includes a laser apparatus outputting a frequency-modulated laser beam, a branching part branching the frequency-modulated laser beam into a reference light and a measurement light, a beat signal generation part generating a beat signal by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured, an extraction part extracting a signal component corresponding to a resonator frequency of the frequency-modulated laser beam, a clock signal generation part generating a first clock signal on the basis of the signal component, a conversion part converting the beat signal into a first digital signal using the first clock signal, and a calculation part calculating a difference in a propagation distance between the reference light and the measurement light on the basis of the first digital signal.