Simultaneous Surface and Subsurface Defect Inspection via Laser-Induced Acoustic Modulation
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Solution Overview
Problem
Current nondestructive inspection methods for optical elements are inadequate in sensitivity and precision for detecting subsurface defects, particularly in ultra-precise optical elements, as they only provide static observations and fail to evaluate dynamic changes of defects, leading to poor evaluation of optical properties and service life.
Innovation Solution
A device and method utilizing lasers of different wavelengths to generate surface waves, modulating static light scattering effects for simultaneous inspection of surface and subsurface defects, incorporating a motion platform for three-dimensional scanning and data analysis to identify defect positions and distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static light scattering methods are used to inspect subsurface defects, then the inspection can be performed nondestructively, but the sensitivity and precision on subsurface defects are poor
Solution Approach 1:
The patent applies dynamic surface wave modulation to transform static light scattering into dynamic scattering patterns. By exciting surface waves at different positions and measuring the temporal variation of scattered light, the system achieves enhanced sensitivity for detecting subsurface defects without requiring overly complex equipment.
Solution Approach 2:
The patent utilizes mechanical surface waves (acoustic waves) to modulate the optical scattering properties of the material. The surface waves create dynamic scattering patterns that enhance the visibility of subsurface defects through their interaction with light, providing improved detection precision while maintaining nondestructive inspection.
2Reliability
If single scattered light collection is used to analyze scattering effects, then the device structure is simple, but it fails to evaluate the dynamic changes of defects in motion
Solution Approach 1:
The patent employs dynamic surface wave excitation and temporal modulation of scattered light to capture the dynamic behavior of defects. By measuring light scattering at different time points during surface wave propagation, the system evaluates defect motion and dynamic changes, significantly improving reliability while managing system complexity through coordinated measurement points.
Solution Approach 2:
The patent implements a feedback mechanism where the measured scattered light signals are processed to identify defect positions and characteristics. The system uses the temporal variation of scattering patterns to feedback about defect dynamics, enabling accurate evaluation of defect motion without requiring excessive complexity in the light collection system.
3Measurement precision
If multiple lasers of different wavelengths are used to generate surface waves and modulate scattering effects, then sensitivity and precision in defect detection are enhanced, but the device complexity increases
Solution Approach 1:
The patent divides the inspection function into separate modules: a laser excitation device for generating surface waves and an inspection device for measuring scattered light. By segmenting these functions and using lasers of different wavelengths for specific purposes (excitation vs. inspection), the system achieves enhanced detection precision while managing overall complexity through functional separation.
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 enhances sensitivity and precision in defect detection, enabling intuitive visualization of defect distribution and effective identification of both surface and subsurface defects, thereby improving the quality control of optical elements.
Implementation Method 1
generating the surface waves on the surface and the subsurface of the optical element to be tested by the lasers
Implementation Method 2
the static light scattering effects of the subsurface defects under the modulation of the surface waves are observed and analyzed
Implementation Method 3
a laser interference inspection device, a laser scattering inspection device
Data Source
AI summary
A device and a method for simultaneously inspecting defects of a surface and a subsurface of an optical element are provided. Combined with laser-induced ultrasound and laser scattering inspection technologies, through generating acoustic sound waves on the surface and the subsurface of the optical element to be tested by lasers, a static light scattering effect of subsurface defects under modulation of the acoustic sound wave is observed and analyzed; through analyzing amplitude and phase changes of scattered light intensity and reflected light intensity, inspection for the defects of the surface and the subsurface of the optical element is realized. The present invention can be applied in quality inspection of precise optical elements, especially in finished product inspection of ultra-precise optical elements having strict requirements on the subsurface defects.