Superluminescent Diode Linear Light Source for Strip Shape Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing shape measurement technologies face challenges in achieving high precision and speed due to speckle noise and difficulty in focusing light into thin linear light, especially when using laser light sources, which also lead to misidentification of surface changes and reduced image transfer speed.
Innovation Solution
A shape measurement apparatus utilizing a superluminescent diode as a linear light source with a spectral half-width of 20 nm or more, applied at an angle between 74 and 88 degrees to the surface, and a power density of 55 mW/cm2, to suppress speckle noise and enhance precision, allowing for higher-speed surface shape measurement of metallic strip-shaped bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser light is used as the linear light source, then measurement precision can be improved, but speckle noise occurs in the reflected image making high precision measurement difficult
Solution Approach 1:
The patent changes the fundamental parameter of the light source from coherent laser light to incoherent or partially coherent light (LED, laser diode with diffuser, superluminescent diode). This parameter change eliminates speckle noise generation while maintaining sufficient coherence for optical lever measurement, thereby resolving the contradiction between measurement precision and speckle noise
Solution Approach 2:
The patent replaces expensive laser light sources with more economical light sources such as LEDs or laser diodes combined with diffusers. These alternative light sources achieve the measurement function without generating speckle noise, providing a cost-effective solution that eliminates the harmful speckle effect
2Object-affected harmful factors
If white light source or other non-laser light sources are used, then speckle noise is reduced, but it is difficult to focus light into thin linear light making high precision measurement difficult
Solution Approach 1:
The patent introduces an intermediary element (diffuser or beam expanding lens) between the light source and the measurement point. This intermediary transforms the light from a point source into a thin linear light pattern while maintaining incoherence, thereby achieving both speckle noise suppression and precise linear light formation
Solution Approach 2:
The patent modifies the spatial distribution parameter of the light by using optical elements to shape the beam into a thin linear pattern. This parameter change allows non-laser light sources to achieve the necessary linear light geometry for accurate surface shape measurement without generating speckle noise
3Measurement precision
If distance between screen and reflection position is increased to reduce speckle noise impact, then detection sensitivity can be maintained, but reflected light spreads making image dark and longer exposure time needed
Solution Approach 1:
The patent creates an optical copy or projection of the surface shape information onto the screen through the optical lever mechanism. By using incoherent light, the system can maintain this optical copy at appropriate distances without speckle noise degradation, preserving both detection sensitivity and image brightness
4Productivity
If laser light is used for high-speed flaw search, then measurement speed can be improved, but speckle noise occurs and longer exposure time is needed reducing measurement speed
Solution Approach 1:
The patent changes the temporal parameter of the measurement system by eliminating speckle noise through incoherent light sources. This removal of noise allows for shorter exposure times while maintaining image quality, thereby increasing the overall measurement speed and productivity for flaw detection
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
The solution enables precise and high-speed measurement of surface shapes while minimizing speckle noise, effectively distinguishing between surface shape changes and dirt, thus improving the accuracy of surface inspections.
Implementation Method 1
a linear light source that includes a superluminescent diode and applies linear light spreading in a width direction of the strip-shaped body to a surface of the strip-shaped body; The linear light source has a spectral half-width of 20 nm or more
Implementation Method 2
measuring a surface shape of a strip-shaped body made of a metallic body on the basis of the principle of an optical lever. Specifically, in Patent Literature 1, linear light applied along the width direction of the strip-shaped body is specularly reflected to be projected on a screen
Data Source
AI summary
A shape measurement apparatus includes: a linear light source that includes a superluminescent diode and applies linear light spreading in a width direction of the strip-shaped body to a surface of the strip-shaped body; a screen on which reflected light of the linear light off the surface of the strip-shaped body is projected; an area camera that captures an image of the reflected light of the linear light projected on the screen; and an arithmetic processing apparatus that calculates the surface shape of the strip-shaped body using the captured image of the reflected light of the linear light captured by the area camera.