Measuring Apparatus Abbe Error Reduction via Reference Member
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fine-shape measuring apparatuses face challenges in achieving high-accuracy measurements due to motion errors from scanners, and existing solutions are either expensive or require complex setups, failing to provide sufficient measurement accuracy without using high-accuracy scanners.
Innovation Solution
A measuring apparatus that uses a reference member held in a fixed position and orientation relative to the workpiece, with a displacement gauge measuring the stylus's displacement directly above it, ensuring the displacement axis and measurement axis are coincident, thereby reducing Abbe errors and enabling high-accuracy measurements without the need for high-accuracy scanners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-accuracy scanner is used to eliminate motion errors, then measurement precision is improved, but device cost and complexity increase significantly
Solution Approach 1:
The patent extracts the measurement function from the scanner by introducing a separate displacement gauge that measures stylus displacement independently of the scanner's motion. This separates the scanning function (which can be simple and inexpensive) from the measurement function (which achieves high accuracy through the displacement gauge), thereby resolving the contradiction between measurement precision and device complexity.
2Device complexity
If a normal scanner is used, then device cost is reduced, but motion errors from the scanner contaminate the measurement data
Solution Approach 1:
The patent introduces a displacement gauge as an intermediary measurement device that directly measures the stylus displacement relative to the workpiece. This intermediary measurement system compensates for the motion errors of the simple scanner by providing an independent, accurate measurement of the actual stylus position, thereby maintaining measurement precision while allowing the use of a cost-effective scanner.
3Device complexity
If the displacement gauge measures from a position away from the stylus, then the optical setup is simplified, but Abbe errors increase
Solution Approach 1:
The patent positions the displacement gauge directly above the stylus tip, creating an equipotential measurement condition where the measurement axis and displacement axis are coincident. This eliminates Abbe errors by ensuring that any lateral motion or rotation of the stylus does not create measurement errors, as the measurement is taken exactly at the point of interest with no lever arm for error amplification.
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 approach allows for reliable high-accuracy measurement of workpiece shapes by isolating the stylus's displacement from scanner motion errors, reducing costs and complexity, while maintaining precision in detecting fine shapes.
Implementation Method 1
The displacement gauge measures a displacement of a specific part of the stylus relative to the reference member
Implementation Method 2
a laser beam is directed to the rear surface of a cantilever, and reflected light is detected by an optical position-sensitive detector
Data Source
AI summary
A measuring apparatus comprising: a reference member held in fixed position and orientation with respect to a workpiece during measurement; a stylus for scanning a surface of the workpiece while being displaced upward and downward in accordance with unevenness of the surface of the workpiece; a displacement gauge for measuring a displacement of a specific part of the stylus relative to the reference member; and a scanner for causing the stylus to scan the workpiece along the surface; wherein the fixed position and orientation of the reference member with respect to the workpiece are not changed even during the operation of the scanner; the up-and-down displacement of the specific part of the stylus is measured relative to the reference member; a fine shape of the workpiece is detected in accordance with the measured displacement of the specific part of the stylus.