Surface Shape Measurement Device Using Differential Interference Contrast Imaging
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Solution Overview
Problem
Conventional surface shape measurement devices require significant computational power and work memory to analyze numerous interference fringe images, leading to lengthy measurement times due to the need for extensive processing of luminance and contrast data.
Innovation Solution
The method involves approximating noise and surface proximity straight lines from integral curves of stacked images to determine the surface position, allowing for reduced analysis processing and faster measurement times by integrating and analyzing fewer images sequentially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional surface shape measurement devices capture and analyze hundreds to thousands of interference fringe images to determine surface height, then measurement precision is improved, but measurement time and computational load increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for surface shape measurement by using differential interference contrast (DIC) imaging to obtain gradient information directly, rather than capturing and analyzing hundreds of interference fringe images. This extraction approach obtains the necessary surface gradient data with far fewer images, reducing measurement time while maintaining precision.
Solution Approach 2:
The patent performs preliminary action by using optical differential operators in the imaging system itself to directly capture gradient information. This preliminary optical processing eliminates the need for extensive post-capture analysis of multiple interference fringe images, as the essential measurement data is obtained directly during image acquisition.
2Measurement precision
If conventional methods perform rough peak detection and fine peak detection processing on all accumulated interference fringe images, then surface shape measurement accuracy is improved, but work memory requirements and computational power increase
Solution Approach 1:
The patent replaces the mechanical/computational system of capturing and analyzing hundreds of interference fringe images with an optical system using DIC imaging and differential operators. This substitution performs the measurement function optically during image capture, eliminating the need for complex computational peak detection processing on large numbers of images.
Solution Approach 2:
The patent changes the fundamental measurement parameter from intensity-based interference fringe analysis to gradient-based DIC imaging. By measuring optical path gradient directly through differential operators rather than analyzing intensity variations in multiple fringe images, the system achieves accurate surface shape measurement with reduced computational complexity.
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 reduces the computational load and work memory requirements, significantly decreasing measurement time while maintaining accurate surface shape determination.
Implementation Method 1
irradiate white light from a light source onto the measurement target and use the luminance information of interference fringes produced by the interference of the light
Data Source
AI summary
A measurement method of a surface shape includes combining N stacked images captured while scanning the measuring head. For a position in the N stacked images, from an integral curve including values of N points, which is obtained by integrating square values or absolute values of the interference signal including values at N points: a start-point-side noise part straight line that approximates a start-point-side noise part, which corresponds to a range where the slope is smaller than the slope in the vicinity of the measurement target surface at the start-point-side than the measurement target surface; an end-point-side noise part straight line that approximates an end-point-side noise part, which corresponds to a range where the slope is smaller than the slope in the vicinity of the measurement target surface at the end-point-side than the measurement target surface; and a surface proximity straight line that approximates surface proximity part.