Surface Roughness Measurement Using Linear Light Projection
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Solution Overview
Problem
Existing surface roughness measurement techniques are unable to detect minute roughness irregularities at high speed across the entire width of a strip-shaped body, as they either rely on point scanning or are limited by the grid pitch of reference patterns.
Innovation Solution
A shape measurement apparatus and method utilizing linear light illumination and imaging, where the angle of incidence is set according to target surface roughness, allowing for the detection of surface roughness distribution based on the width distribution of a light strip projected onto a screen, enabling high-speed measurement of minute irregularities across the entire surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If point scanning method is used to measure surface roughness, then measurement precision can be achieved, but measurement speed deteriorates
Solution Approach 1:
The patent transitions from point-by-point measurement to full-field simultaneous measurement by projecting a line-shaped light beam across the entire measurement width and capturing the reflected light pattern with a two-dimensional imaging device. This dimensional change allows all measurement points to be measured simultaneously rather than sequentially, resolving the contradiction between precision and speed.
Solution Approach 2:
The patent creates an optical copy of the surface topography by projecting light and capturing the reflected pattern. The imaging device records a two-dimensional image that represents the entire surface profile, allowing rapid capture of surface roughness information without physical contact or sequential scanning, thus achieving both precision and high speed.
2Area of stationary object
If grid pattern reference is used for surface measurement, then measurement coverage is improved, but detection precision for fine irregularities deteriorates due to grid pitch limitations
Solution Approach 1:
The patent eliminates the grid pattern reference entirely and uses only a line-shaped light beam for illumination. By removing the grid structure, the measurement system is no longer constrained by grid pitch, allowing detection of fine roughness irregularities smaller than any grid spacing would permit, while still achieving full width coverage through the line beam geometry.
3Device complexity
If conventional optical measurement methods are used, then equipment complexity is reduced, but measurement capability for high-speed full-surface detection deteriorates
Solution Approach 1:
The patent replaces mechanical scanning systems with an optical field-based measurement approach. Instead of moving a sensor point-by-point across the surface, the system uses a line-shaped light beam and imaging device to capture the entire surface profile optically. This substitution of mechanical movement with optical field measurement enables high-speed full-surface detection while maintaining relatively simple equipment architecture.
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
Enables the detection of minute roughness irregularities at high speed across the entire width of a strip-shaped body, improving measurement efficiency and accuracy by analyzing the width distribution of a light strip imaged on a screen.
Implementation Method 1
a light source that irradiates a surface of a moving strip-shaped body with linear light at a prescribed angle of incidence from an upstream side or a downstream side in a movement direction of the strip-shaped body; a screen on which reflected light of the linear light on the surface of the strip-shaped body is projected
Data Source
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AI summary
[Object] To provide a shape measurement apparatus that is capable of detecting minute roughness irregularity at high speed across the entire width on the entire surface of a measurement object. [Solution] Provided is a shape measurement apparatus including: a light source configured to irradiate a surface of a moving strip-shaped body with linear light diagonally from an upstream side in a movement direction of the strip-shaped body; a screen configured such that reflected light of the linear light on the surface of the strip-shaped body is projected on the screen; an imaging unit configured to image the reflected light of the linear light projected on the screen; and an arithmetic processing unit configured to acquire surface roughness distribution of the strip-shaped body on the basis of width distribution of a light strip of the reflected light of the linear light projected on the screen. The angle of incidence of the light source with respect to the strip-shaped body is set in accordance with target surface roughness of the surface of the strip-shaped body.