Direct display of the deflection function of optical fiber preforms

Area of Science:

• Optical Engineering
• Materials Science
• Metrology

Background:

• Accurate characterization of optical fiber preforms is crucial for manufacturing high-quality optical fibers.
• Existing methods for refractive-index profiling face challenges, particularly with complex dopant profiles and ray crossing issues.
• The focusing method is a common technique but has limitations in resolving certain preform characteristics.

Purpose of the Study:

• To present a novel astigmatic optical system for direct display of an optical fiber preform's deflection function.
• To enable direct quality evaluation of preforms and computer-based reconstruction of refractive-index profiles.
• To address and resolve the ray crossing problem inherent in other measurement techniques.

Main Methods:

• Development and implementation of an astigmatic optical system.
• Direct display of the deflection function of optical fiber preforms.
• Digitization and computer recording of the deflection function for refractive-index profile reconstruction.
• Experimental comparison with the established focusing method.
• Error analysis based on the uncertainty principle.

Main Results:

• The astigmatic optical system provides a direct display of the deflection function.
• The method successfully resolves the ray crossing problem.
• Demonstrated superior accuracy in measuring profiles of boron-doped preforms compared to the focusing method.
• Experimental data and error analysis confirm the system's performance and reliability.

Conclusions:

• The astigmatic optical system offers a significant advancement in optical fiber preform metrology.
• It provides a more accurate and reliable method for evaluating preform quality and reconstructing refractive-index profiles.
• The system's ability to overcome ray crossing issues makes it particularly valuable for complex preform designs.