Cross-Polarized Confocal Microscopy as a Method for Sub-Surface Damage Detection in Glass and Crystalline Substrates

Abstract

This body of work discusses the modeling and design of a prototype Cross-Polarized Confocal Microscope used to image sub-surface defects/damage at depths < 25 um below the surface of transparent glass and crystalline substrates common to precision optics applications as a result of lapping and polishing processes. Discussions of motivations and existing technologies are also discussed. This work delves into the basic principles behind confocal microscopy, polarization, and their crossover in this application. The focus of this work was to create a simulation capable of benchmarking the relative improvements in imaging performance using cross-polarized confocal microscopy (XPCM) as compared to standard confocal techniques. An overview of the FRED model and scripting within the model for automation, as well as the design process is given, and final simulated results are shown. To conclude, a summary of the prototype build completed by the Laser Optics Fundamentals Group in Corning Inc, Sullivan Park using this body of work as a design basis, with initial SSD measurement results is covered.