Imagery of local defects in multilayer components by short coherence length interferometry

Area of Science:

• Optical Engineering
• Metrology
• Materials Science

Background:

• Multilayer optical components are crucial in various laser systems.
• Detecting internal defects is essential for performance and reliability.
• Existing methods may lack sensitivity or resolution for subsurface defects.

Purpose of the Study:

• To develop and demonstrate a microscopy technique for imaging local defects within multidielectric optical components.
• To enhance the contrast and detectability of subsurface defects.
• To validate the method on interfaces of multilayer optical components like laser mirrors.

Main Methods:

• Utilizing a specialized Linnik interference microscope configuration.
• Employing a short coherence length light source for thin-slice imaging (~1 micrometer).
• Implementing a dark-field configuration with object tilting to maximize defect contrast.

Main Results:

• Successfully extracted the amplitude scattered by local defects from interference images.
• Demonstrated the imaging of point defects on interfaces of multilayer optical components.
• Achieved enhanced defect contrast through the dark-field configuration.

Conclusions:

• The proposed Linnik interference microscopy method is effective for imaging internal defects in optical components.
• The technique offers improved sensitivity and contrast for defect detection.
• This method has potential applications in quality control and failure analysis of optical devices.