Dual-Comb Interferometry With Internal Phase Compensation
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Solution Overview
Problem
Existing distance measuring devices face challenges in maintaining high accuracy due to environmental factors, particularly temperature changes affecting the optical path length, which are difficult to stabilize, especially in non-integral designs like coordinate measuring machines.
Innovation Solution
A dual-comb interferometric method and device that splits the signal comb before emission, using a chromatic splitter to create a non-target signal comb for internal compensation, allowing separation of phase shifts related to the target distance from those caused by environmental factors, enabling accurate distance measurement without temperature stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature stabilization is implemented to compensate for environmental influences on optical path length, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The signal comb is segmented into two separate combs: a first signal comb that travels through the measurement optical path to the target, and a second signal comb that travels through a reference optical path. This segmentation allows independent measurement of phase shifts in each path, enabling compensation of environmental influences without requiring temperature stabilization of the entire device.
Solution Approach 2:
A frequency comb generator serves as an intermediary device that generates both the signal comb and local comb with stabilized frequencies. The frequency comb generator acts as a reference that compensates for environmental influences on the optical paths, eliminating the need for complex temperature stabilization systems.
2Measurement precision
If frequency comb generation with stabilization is used to achieve high measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The frequency comb generator is designed to perform multiple functions: generating the signal comb for measurement, generating the local comb for reference, and providing frequency stabilization. This multi-functionality reduces the need for separate stabilization components and simplifies the overall device architecture while maintaining high measurement precision.
3Ease of operation
If the measuring device is designed with non-integral structure for flexibility, then ease of operation is improved, but measurement precision deteriorates due to difficult temperature stabilization
Solution Approach 1:
The measurement system is segmented into independent optical paths (measurement path and reference path) that can be independently managed. This allows the device to maintain measurement precision through differential measurement while preserving the flexibility of non-integral design, as environmental influences are compensated by comparing the two independent paths.
Solution Approach 2:
The system uses feedback from the reference optical path to compensate for environmental influences on the measurement optical path. By continuously monitoring and comparing the phase shifts in both paths, the system automatically compensates for temperature and other environmental variations, maintaining precision without requiring rigid thermal control of the entire device.
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 compensates for environmental influences on the optical path, ensuring high measurement accuracy by isolating target-related phase shifts, allowing for flexible and compact device placement without complex temperature stabilization.
Implementation Method 1
splitting of the signal comb directly before emitting (at the emission point) into a non-target signal comb and a target signal comb by chromatic splitting
Implementation Method 2
superposing of local comb and signal comb having travelled along defined (device internal) optical paths
Implementation Method 3
The reflected optical radiation is converted into an electrical signal in the device by a photosensitive element
Implementation Method 4
Dual-comb schemes are also known, which rely on multiheterodyne detection by coherent superposition of a pair of slightly detuned frequency combs
Data Source
AI summary
An opto-electronic dual-comb interferometric distance measuring method and device wherein a signal comb is chromatically divided into a target signal comb and a non-target signal comb at a emission position, preferably by an optical interleaver in a measurement probe of the device. Only the target signal comb serves as a free beam emitted to the target. The non-target signal comb serves for generation of additional or compensation internal phase differences. Thus, the distance to the target is based on first, target related phase differences and on the second, internal compensation phase differences.