Optical Gain Correction for Stable Critical Illumination Inspection
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Solution Overview
Problem
Existing optical apparatuses face challenges in accurately correcting brightness distribution and power fluctuations in critical illumination due to variations in light source intensity, which affect defect detection precision.
Innovation Solution
Incorporating a gain changing unit that adjusts gains based on signals from a second detection unit to correct signals from a first detection unit, and employing a drive unit to reposition the illumination spot or perform rescanning when significant fluctuations occur, along with optical adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain correction is applied to compensate for light source intensity variations, then measurement precision improves, but device complexity increases due to additional detection units and control mechanisms
Solution Approach 1:
A second detection unit is introduced as an intermediary to monitor light source intensity variations. This separate monitoring channel provides feedback information that is used to adjust the gain of the first detection unit, thereby compensating for intensity fluctuations without requiring direct modification of the primary detection path.
Solution Approach 2:
The patent implements a feedback control mechanism where the evaluation value from the second detection unit is continuously monitored. When the evaluation value changes by more than a threshold amount, the gain changing unit adjusts the predetermined gain accordingly. This closed-loop feedback system automatically compensates for light source intensity variations, improving measurement precision while maintaining stable operation.
2Stability of the object's composition
If frequent gain adjustments are made to track light source variations, then brightness distribution stability improves, but loss of time increases due to repeated measurements and corrections
Solution Approach 1:
The patent implements dynamic gain adjustment where the predetermined gain is not fixed but is modified in real-time based on light source intensity variations detected by the second detection unit. The gain changing unit dynamically adapts the correction parameters to match current operating conditions, allowing the system to maintain accuracy under varying conditions without requiring complete re-measurement sequences.
Solution Approach 2:
The system performs preliminary evaluation by continuously monitoring the evaluation value from the second detection unit before full defect detection is required. By detecting threshold exceedances in advance, the system can proactively adjust gains to prevent brightness distribution instability, rather than waiting for defects to be missed or re-measurements to become necessary.
3Reliability
If threshold-based gain changing is implemented to filter noise, then reliability improves, but measurement precision may deteriorate due to delayed response to actual light source changes
Solution Approach 1:
The patent changes the parameter being monitored from raw detection signals to an evaluation value that represents the overall state of light source intensity. By base the gain adjustment decisions on this derived evaluation parameter rather than individual pixel values, the system can apply threshold-based control that filters out local variations and noise while still responding reliably to genuine light source intensity changes that affect the entire field of view.
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
Enhances the accuracy of defect detection by stabilizing brightness distribution and power fluctuations, allowing for precise inspection of objects under critical illumination.
Implementation Method 1
a first detection unit configured to detect light coming from an object illuminated by light emitted from a light source
Implementation Method 2
a second detection unit configured to detect a part of the light emitted from the light source
Data Source
AI summary
An optical apparatus or the like including a gain changing unit that changes a predetermined gain is provided. An optical apparatus according to the present disclosure includes: a first detection unit configured to detect light coming from an object illuminated by light emitted from a light source and output signals in association with a plurality of positions; a second detection unit configured to detect a part of the light emitted from the light source and output signals in association with a plurality of positions; a signal correction unit configured to correct the signals from the first detection unit based on predetermined gain values determined in advance for the respective positions; and a gain changing unit configured to change the predetermined gain values based on the signals from the second detection unit.