Refractive index profilometry using the total internally reflected light field

Area of Science:

• Optics and Photonics
• Materials Science
• Biophysics

Background:

• Quantitative refractive index mapping is crucial for material characterization and biological studies.
• Existing techniques may lack spatial resolution or require complex sample preparation.

Purpose of the Study:

• To develop and validate a full-field, polarization-based optical technique for quantitative refractive index evaluation.
• To enable precise measurement of refractive index distribution in both macro and micro samples.

Main Methods:

• A prism-based setup utilizing total internal reflection of linearly polarized light.
• Digital recording of two intensity frames with varying analyzer orientations.
• An algorithm to compute phase difference from intensity data for refractive index determination.

Main Results:

• Successfully quantified spatial refractive index variations in a laser-etched glass plate.
• Demonstrated the technique's applicability to biological samples, specifically red blood corpuscles.
• Achieved depth-resolved measurements within a few hundred nanometers using evanescent field penetration.

Conclusions:

• The presented technique offers a simple yet effective method for quantitative refractive index mapping.
• Its non-destructive nature and depth sensitivity make it suitable for analyzing thin sample sections.
• The method holds potential for applications in materials science, microfluidics, and biomedical imaging.