Two-Axis Turning Mechanism for Laser Interferometer
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Solution Overview
Problem
Existing optical axis polarization type laser interferometers have complex mechanism designs for the two-axis turning mechanism, leading to high costs and mechanical instability, particularly due to the need for precise alignment and control of the reference sphere's center coordinates, which are affected by thermal expansion and friction.
Innovation Solution
A two-axis turning mechanism design where the fixing portion of the first axis turning mechanism is placed at the inner circumference, with the reference sphere supported there, and the moving portion of the first axis turning mechanism located at the outer circumference, allowing for a simplified and compact mechanism with integrated components, reducing unnecessary spacing and using displacement gauges like electrostatic capacitance or eddy current types to measure changes in distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional two-axis turning mechanism with the reference sphere at the center is used, then the measurement reference is established, but the mechanism design becomes complex and costly
Solution Approach 1:
The patent inverts the traditional arrangement by placing the reference sphere at the outer circumference rather than at the center. The first axis turning mechanism's fixing portion is positioned at the inner circumference while the moving portion is at the outer circumference where the reference sphere is located. This inversion simplifies the mechanism design while maintaining measurement precision by using the reference sphere as both the measurement reference and a structural component.
Solution Approach 2:
The patent merges the reference sphere supporting function with the first axis turning mechanism by integrating the reference sphere into the outer circumference structure. Instead of having a separate supporting portion for the reference sphere, the design combines these functions, eliminating unnecessary components and simplifying the overall mechanism while maintaining the reference function.
2Manufacturing precision
If a slender reference sphere supporting portion is used to reach the center, then the reference sphere can be positioned, but mechanical stability decreases due to thermal expansion and friction
Solution Approach 1:
Instead of extending a slender supporting portion from the center to reach the reference sphere, the patent inverts the approach by positioning the reference sphere at the outer circumference where it can be directly supported by the moving portion of the first axis turning mechanism. This eliminates the need for long, slender supporting structures that are prone to thermal expansion and mechanical instability.
Solution Approach 2:
The patent extracts and eliminates the slender reference sphere supporting portion from the mechanism design. By repositioning the reference sphere to the outer circumference, the design removes the problematic intermediate supporting structure that caused mechanical stability issues, while still achieving accurate reference sphere positioning through the turning mechanism.
3Manufacturing precision
If the reference sphere is placed at the center with a long supporting portion, then positioning is achieved, but the mechanism becomes less compact and more costly
Solution Approach 1:
The patent merges the reference sphere positioning function with the outer circumference structure of the turning mechanism. By placing the reference sphere at the outer circumference rather than requiring a long supporting portion from the center, the design achieves compactness while maintaining positioning accuracy through the integrated moving portion of the first axis turning mechanism.
4Measurement precision
If complex alignment and control mechanisms are used for the reference sphere, then measurement accuracy is maintained, but friction and thermal expansion effects increase
Solution Approach 1:
The patent extracts and eliminates the complex alignment and control mechanisms that caused friction and thermal expansion issues. By repositioning the reference sphere to the outer circumference and integrating it with the turning mechanism structure, the design reduces the number of intermediate components and contact points, thereby minimizing friction and thermal expansion effects while maintaining measurement accuracy.
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 design simplifies mechanism design and manufacturing, reduces production costs, and enhances mechanical stability by eliminating the need for a slender reference sphere supporting portion, while maintaining high accuracy in measuring distance changes with reduced influence from thermal expansion and friction.
Implementation Method 1
detects a displacement of the retro-reflecting means 12 by utilizing interference of the laser beam reflected in the return direction
Implementation Method 2
The displacement gauge 60 may be an electrostatic capacitance type displacement gauge
Implementation Method 3
or an eddy current type displacement gauge
Data Source
AI summary
An optical axis polarization type laser interferometer including a reference sphere which forms a reference of measurement, a retro-reflecting means disposed at a measurement object, a laser interference measuring apparatus for outputting a measurement value corresponding to an increase or a decrease in the distance to and from the retro-reflecting means; and a two-axis turning mechanism for turning an emission beam of the corresponding laser interference measuring apparatus centering around the reference sphere, which measures, with the center coordinates of the reference sphere used as the reference, the distance to and from the retro-reflecting means where the optical axes of the emission beam from the laser interference measuring apparatus mounted on the two-axis turning mechanism and a return beam become parallel to each other, wherein the fixing portion of the first axis turning mechanism installed at the base part of the apparatus is disposed at the inner circumference thereof, the reference sphere is placed at the fixing portion thereof, and at the same time, the moving portion of the first axis turning mechanism is placed at the outer circumference of the fixing portion, and the second axis turning mechanism is mounted on the moving portion thereof. Therefore, complexities in mechanism design can be simplified to a large extent with respect to the first axis turning mechanism that composes the two-axis turning mechanism.