Defect Inspection Using Parallel Laser Beams and Particle Gas
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Solution Overview
Problem
Existing defect inspection methods for porous and non-porous articles, particularly those with complex shapes like honeycomb structures, face challenges in distinguishing defects from noise caused by secondary reflections of laser beams, leading to reduced sensitivity in defect detection.
Innovation Solution
The method involves using multiple laser beams applied in specific orientations and planes to inspect defects, combined with particle-containing gas, allowing for perpendicular photography to reduce noise and enhance sensitivity by distinguishing defect-related luminance from other bright spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser beam is applied to particles discharged from the inspection target to visualize defects, then defect detection sensitivity is improved, but noise is generated due to secondary reflections from the end face edge
Solution Approach 1:
The patent changes the spatial arrangement by applying the laser beam in a direction parallel to the end face rather than perpendicular to it. This dimensional change in beam orientation allows the light to pass through particles discharged from the inspection target without generating secondary reflections from the end face edge, thereby eliminating noise while maintaining defect detection sensitivity
Solution Approach 2:
The patent employs asymmetric illumination geometry where the laser beam is positioned at a specific angle parallel to the end face. This asymmetric arrangement creates a configuration where particles are illuminated from the side, allowing their light scattering to be captured while avoiding the symmetric reflection path that would create noise from the end face edge
2Measurement precision
If multiple laser beams are applied in different orientations to reduce noise, then defect detection accuracy is improved, but inspection time increases
Solution Approach 1:
The patent combines multiple laser beam irradiations with different orientations into a single integrated inspection process. By applying laser beams in multiple directions simultaneously or in rapid succession and capturing images from perpendicular views, the system merges the noise-reduction benefits of multi-directional illumination with efficient single-shot detection, avoiding the time penalty of sequential inspections
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 effectively reduces noise interference, enabling high-sensitivity defect detection in complex-shaped inspection targets by analyzing the total image luminance and specific luminance patterns from multiple laser beam interactions.
Implementation Method 1
applying light with high directivity to the particles discharged from the inspection target so that the light travels near the inspection target to visualize the particles
Implementation Method 2
light with high directivity (laser beam) is scattered by the particles, reflected by the edge of the end face of the inspection target (i.e., the edge shines), and serves as noise
Data Source
AI summary
A method of inspecting defects in an inspection target includes (1) a step of supplying a particle-containing gas to one end face of the inspection target under pressure, applying in parallel a first laser beam to the vicinity of the other end face of the inspection target, and photographing such end face from a position vertical to such end face, (2) a step of supplying a particle-containing gas to the one end face of the inspection target under pressure, applying in parallel a second laser beam to the vicinity of the other end face of the inspection target, and photographing such end face from a position vertical to such end face, and (3) a step of specifying defects in the inspection target from photographic results obtained by the steps (1) and (2).