Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Microscopy Museum
Virtual Microscopy
Web Resources
License Info
Image Use
Custom Photos
Site Info
Contact Us

The Galleries:

Photo Gallery
Silicon Zoo
Chip Shots
DNA Gallery
Amino Acids
Religion Collection
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Total Internal Reflection Fluorescence Microscopy
Interactive Tutorials

Polarized Light Evanescent Intensities

The light intensity at a TIRFM interface is a function of the illumination angle of incidence and the polarization of the incident light. This interactive tutorial explores how evanescent field intensities vary as a function of critical angle and the refractive index of the glass medium.

To operate the tutorial, use the Glass Refractive Index slider to change the refractive index value from a range of 1.45 to 1.78, corresponding to the differences between fused quartz and sapphire, respectively. As the slider is translated, the curves in the tutorial window display a change in both the critical angle and the relative intensities. Note how the evanescent field intensities drop as the refractive index and corresponding critical angle are decreased.

The p and s evanescent intensities are illustrated in the tutorial window as a function of incident angle for transmitted light in the lower refractive index medium when passed through an interface composed of a medium of variable refractive index (n(1) = 1.45-1.78) and water or an aqueous buffer solution (n(2) = 1.33). These calculations assume a condition of total internal reflection and require a critical angle of that is dependent upon the refractive index of the glass medium. Intensity, plotted on the ordinate, is expressed as the ratio of evanescent intensity at the interface (z equals zero) to the incident intensity for each polarization angle. It is interesting to note that the evanescent intensities for both polarization orientations exhibit a range between one and five times that of the plane wavefront incident intensity for angles within 15 degrees of the critical angle.

Contributing Authors

Daniel Axelrod - Department of Biophysics, University of Michigan, 930 North University Ave., Ann Arbor, Michigan 48109.

John C. Long and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.


Questions or comments? Send us an email.
© 1995-2019 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Tuesday, Sep 11, 2018 at 12:06 PM
Access Count Since April 15, 2001: 16966
For more information on microscope manufacturers,
use the buttons below to navigate to their websites: