Spherical Surface Shape Measurement Using Dynamic Illumination Angle Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-contact shape measurement techniques for spherical surfaces face challenges with measurement accuracy due to illumination angle deviations and temperature changes, particularly when measuring surfaces that are not true spheres, leading to errors in distance measurement.
Innovation Solution
A shape measurement apparatus and method that includes a sensor system capable of rotating and moving to maintain a fixed distance and illumination angle, utilizing a laser displacement meter with a control device to calculate and correct for angular, straightness, and temperature characteristic errors, ensuring accurate measurement by aligning the spherical center with the sensor's rotational center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a non-contact type shape measurement technique using light from a laser displacement meter is used, then measurement can be performed without damaging the measurement surface and in shorter time, but measurement accuracy changes depending on illumination angle deviation from 90 degrees
Solution Approach 1:
The patent applies dynamics by making the illumination angle adjustable rather than fixed. The shape measurement apparatus allows dynamic adjustment of the illumination angle to optimize measurement conditions for different surface geometries, enabling both rapid non-contact measurement and maintained accuracy by adapting the angle to the specific measurement requirements.
Solution Approach 2:
The patent changes the illumination angle parameter to resolve the contradiction. By varying the illumination angle according to the measurement object's characteristics and surface geometry, the system achieves accurate measurements without requiring the optical axis to be perpendicular to the surface, thus maintaining both speed and precision.
2Measurement precision
If computational correction of measurement error due to inclined illumination is applied, then measurement accuracy can be maintained, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for various illumination angles and surface geometries. Instead of performing complex real-time calculations during measurement, the system uses pre-computed correction data that can be quickly applied, reducing computational complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent implements feedback by using the measured surface geometry information to automatically adjust the illumination angle or select appropriate correction factors. The system continuously monitors measurement conditions and adjusts parameters accordingly, creating a closed-loop system that maintains accuracy without requiring complex manual intervention.
3Measurement precision
If various stages and fixture are set to a relationship based on a fixed algorithm to reduce reflection angle, then measurement accuracy on edge portions is improved, but ease of operation decreases
Solution Approach 1:
The patent applies self-service by enabling the measurement system to automatically adjust its own configuration based on the measured object. The apparatus autonomously determines optimal stage and fixture relationships without requiring manual setup based on fixed algorithms, reducing operational complexity while maintaining measurement accuracy on edge portions.
Solution Approach 2:
The patent makes the stage and fixture relationships dynamic rather than fixed. The system can adaptively adjust the relative positions and orientations of measurement components based on the specific geometry of the object being measured, eliminating the need for rigid pre-programmed setups and improving ease of operation.
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 enhances measurement accuracy by minimizing angular and straightness errors and temperature-induced errors, allowing for precise shape measurement of spherical surfaces regardless of their true spherical nature, and enables accurate evaluation of both measurement surfaces and objects with protrusions or recessions.
Implementation Method 1
a sensor configured to emit light onto the measurement surface to perform non-contact measurement of a distance between the sensor and the measurement surface
Data Source
AI summary
A shape measurement apparatus includes: a holder for holding a measuring object having a spherical measurement surface; a sensor configured to emit light onto the measurement surface to perform non-contact measurement of a distance between the sensor and the measurement surface and output a measured value; a rotation mechanism for rotating the sensor around a first axis; a sensor movement mechanism for moving the sensor along a second axis orthogonal to the first axis so as to be movable across an intersection of the second axis with the first axis; a holder movement mechanism for moving the holder along a vertical direction and on a plane orthogonal to vertical direction; and a control device configured to: calculate the shape of the measurement surface based on the measured value; calculate a spherical center of the measurement surface; and cause the holder movement mechanism to match the spherical center with the intersection.