Research on Total Internal Reflection Detection Technology for Subsurface Defects of Optical Elements Based on...

Area of Science:

• Optics and Photonics
• Materials Science
• Metrology

Background:

• Subsurface defects in precision optical elements degrade performance by enhancing light fields, increasing laser absorption, and reducing mechanical properties.
• High-precision quantitative automatic detection of these defects is crucial for optical element manufacturing.
• Existing methods may have limitations in resolution, depth, or require fluorescent substances.

Purpose of the Study:

• To develop and validate a novel, non-destructive method for high-precision detection of subsurface defects in optical elements.
• To achieve accurate depth and location measurements of internal defects.
• To overcome limitations of current defect detection techniques.

Main Methods:

• A spectral confocal scattering measurement system was designed, incorporating a dispersive lens group (480-670 nm).
• The system integrates spectral confocal technology with total internal reflection to minimize surface scattered light interference.
• The method operates without the need for fluorescent substances, enabling non-destructive evaluation.

Main Results:

• The developed method achieved an axial resolution of 0.8 μm.
• A measuring depth range of 0.94 mm was demonstrated.
• Experimental verification confirmed accurate measurement of subsurface defect depth and location.

Conclusions:

• The spectral confocal scattering measurement method is feasible and effective for high-precision, non-destructive detection of subsurface defects.
• This technique offers a significant advancement in quality control for precision optical element manufacturing.
• The method provides reliable quantitative data on defect characteristics crucial for performance assessment.