Confocal Fabry-Perot Interferometer with Folding Mirror
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Solution Overview
Problem
Existing position acquisition devices using Fabry-Perot interferometers face challenges with high construction costs, complex mounting requirements, and limited measuring range due to stringent mirror parallelism demands, which restrict their application and accuracy.
Innovation Solution
A confocal Fabry-Perot interferometer design with a folding reflective surface between the resonator mirrors, allowing for a simpler and cost-effective setup that is less sensitive to vibrations and easier to install, while maintaining high accuracy and extending the measuring range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Fabry-Perot interferometer is used for accurate position acquisition, then measurement precision is improved, but device complexity and construction costs increase due to high mirror parallelism demands
Solution Approach 1:
The patent introduces a folding mirror to change the spatial arrangement of the interferometer components. By folding the optical path, the resonator can be configured in a compact geometry that is less sensitive to mirror parallelism errors, thus maintaining measurement precision while reducing construction complexity
Solution Approach 2:
The patent modifies the geometric parameters of the interferometer by using a confocal configuration with specific mirror curvature radii and a folding mirror at a defined angle. This parameter optimization reduces the sensitivity to mirror parallelism while preserving the interferometer's measurement accuracy
2Measurement precision
If stringent mirror parallelism demands are imposed, then measurement precision is improved, but ease of manufacture and installation deteriorate
Solution Approach 1:
By folding the optical path using a mirror positioned at a specific angle (e.g., 45 degrees), the patent creates a compact confocal geometry where the mirrors can be mounted with relaxed parallelism tolerances, making the device easier to manufacture and install while maintaining precision
Solution Approach 2:
The folding mirror acts as an intermediary element that decouples the strict parallelism requirements from the main resonator mirrors. This intermediate component allows the use of standard mounting techniques while achieving the required optical precision
3Device complexity
If a compact design is implemented, then device complexity is reduced, but measuring range may be limited
Solution Approach 1:
The folding mirror configuration allows the optical path length to be extended in a folded geometry, enabling a large measuring range while keeping the physical footprint of the device compact. The light travels a longer path within a smaller space, resolving the contradiction between size and range
4Reliability
If the interferometer is made insensitive to vibration, then reliability in practical environments is improved, but device complexity may increase
Solution Approach 1:
The confocal folded geometry with specific mirror curvatures and folding angles creates an optical path that is inherently less sensitive to vibrations. The symmetric confocal configuration and folded path reduce the impact of mechanical disturbances, improving reliability without adding complex vibration isolation systems
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 confocal design provides a stable, compact, and cost-effective solution for precise position determination with a large measuring range, enabling its use in various applications, including environments with vibrations and limited space, and achieving sub-nanometer positioning accuracy.
Implementation Method 1
generating an interference pattern dependent on a position of an object by means of a confocal Fabry-Perot interferometer
Implementation Method 2
a first and a second resonator reflective surfaces; and a folding reflective surface arranged in a beam path between the first and the second resonator reflective surfaces
Data Source
AI summary
Device and method for acquiring position with a confocal Fabry-Perot interferometer. In a general aspect, the device for acquiring position may include an arrangement for acquiring position where the acquiring arrangement has a confocal Fabry-Perot interferometer. In another general aspect, a method for acquiring position may include generating an interference pattern dependent on a position of an object by a confocal Fabry-Perot interferometer; detecting the interference pattern to obtain a measuring signal; and evaluating the measuring signal.