Automatic Detection of Large Caliber Cambered Optical Surface Defects
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Solution Overview
Problem
Current methods for detecting surface defects on large caliber cambered optical elements rely on inefficient and inaccurate manual visual inspection, and existing machine vision technologies fail to provide real-time detection with sufficient precision, especially for cambered surfaces.
Innovation Solution
An automatic detection system comprising a sensor sub-system, imaging sub-system, illumination sub-system, rotatable workpiece table, and guide rail, which enables multi-axis coordination and full-caliber scanning to detect surface defects using a multi-angle annular illumination and high-resolution line array camera, improving contrast and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual visual detection is used, then the detection process is simple to implement, but the detection efficiency and accuracy are low
Solution Approach 1:
The patent replaces manual visual detection with an automated optical detection system comprising a line array camera, multi-angle annular illumination device, and rotatable workpiece table. This substitution eliminates subjective human judgment and significantly improves detection efficiency while maintaining operational simplicity through automated control
Solution Approach 2:
The detection system is designed to handle various types of surface defects (scratches, dents, cracks, chipping) on large caliber cambered optical elements of different sizes. The rotatable workpiece table and multi-angle illumination provide universal detection capability for diverse defect types and geometries
2Measurement precision
If conventional machine vision detection is used, then the detection process is automated, but the detection accuracy is low and detection time is long
Solution Approach 1:
The patent employs multi-angle annular illumination that provides different illumination angles for different regions of the cambered surface. This localized optimization of illumination quality enhances the visibility and contrast of defects in specific areas, thereby improving overall detection accuracy without requiring excessive scanning time
Solution Approach 2:
The system transitions from conventional 2D area array imaging to 3D scanning detection using a line array camera combined with rotatable workpiece table. This dimensional change enables comprehensive surface coverage and depth information acquisition, improving both accuracy and efficiency for cambered surfaces
3Measurement precision
If single-angle illumination is used, then the illumination system is simple, but the contrast of defect images is insufficient
Solution Approach 1:
The illumination system is segmented into multiple independent LED light sources arranged in an annular configuration, each emitting at different angles. This segmentation allows selective illumination of different surface regions, enhancing defect contrast through multi-angle lighting while maintaining modular system simplicity
Solution Approach 2:
The patent converts the harmful effect of specular reflection on cambered surfaces into a beneficial detection mechanism. By using multi-angle illumination, the system captures scattered light from defects that would otherwise be obscured, transforming reflection challenges into enhanced defect visibility through scattered light imaging
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 system achieves enhanced detection precision and efficiency by uniformly illuminating and imaging scattered light from defects, allowing for real-time, accurate detection of surface defects on cambered optical elements.
Implementation Method 1
the sensor sub-system obtains scattered images of the defects
Implementation Method 2
specular reflection images do not enter the imaging sub-system
Implementation Method 3
a high-resolution line array camera, and a high-speed data acquisition card connected to camera signals
Data Source
AI summary
Embodiments of the present disclosure relate to a measuring method and device for measuring surface defects of a cambered optical element, which belongs to the field of photoelectric detection technology. The device includes a sensor measuring head, a rotatable workpiece table, an automatic sampling device, and a spraying device. The sensor measuring head includes an illumination sub-system and a line scan imaging sub-system, the illumination sub-system provides an illumination of high uniformity and high brightness for a surface of a sample to be detected, the rotatable workpiece table and the imaging sub-system are configured for performing a ring belt scanning and a high resolution scatter imaging to the defects on an optical surface region. The automatic sampling device is used as a mechanical arm in an automatic production for automatically clamping optical elements; the spraying device is activated once foreign matters such as dust and impurities are detected on the surface, so as to accurately remove false defects such as dust and impurities on the surface of the piece to be detected. Embodiments of the present disclosure effectively solve the problem that the surface defect detection of the large caliber optical element is difficult and the efficiency thereof is low, and can quickly measure surface defects of a large caliber planar, spherical and cambered optical element.