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Substrate effects on absorption of coated surfaces.
Applied Optics
|November 25, 2010
Summary
Photothermal deflection accurately maps surface absorption. Substrate properties significantly impact coated component losses, especially near surfaces and interfaces.
Area of Science:
- Materials Science
- Optical Engineering
- Surface Science
Background:
- Optical coatings are crucial for component performance.
- Substrate properties can significantly influence total optical losses.
- Understanding absorption at interfaces and surfaces is key.
Purpose of the Study:
- To map surface absorption of bare and coated substrates using photothermal deflection.
- To investigate the influence of substrate type and surface contamination on coated component absorption.
- To analyze absorption localization in coated films.
Main Methods:
- Photothermal deflection technique for absorption mapping.
- Comparative analysis of BK7 and fused-silica substrates.
- In-situ mapping before and after coating, and post-annealing.
Main Results:
- Substrate type strongly affects coated-substrate absorptance.
- Surface contamination of bare substrates impacts total absorption.
- Absorption is localized at the substrate's near-surface and film interfaces.
Conclusions:
- Substrate selection is critical for minimizing optical losses in coated components.
- Photothermal deflection is effective for diagnosing absorption in optical coatings.
- Interface and near-surface absorption are primary contributors to optical losses.
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