NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PUBLICATIONS

Direct method of extracting complex refractive index from routine Fourier transform infrared reflectance/transmittance measurements

Published

Author(s)

Braden E. Czapla, Leonard M. Hanssen

Abstract

We describe an algorithm to extract the complex refractive index of a material from reflectance and transmittance measurements commonly taken by spectrophotometers. The algorithm combines Kramers- Kronig analysis with an inversion of Fresnel's equations to provide a direct method of solving for the refractive index which is accurate, even for weakly absorbing materials. We discuss the details of the uncertainty analysis of the algorithm. The algorithm is validated by extracting the complex refractive index of polydimethylsiloxane between 2 micrometers and 18 micrometers and comparing against existing literature.
Volume
11485
Conference Dates
August 24-28, 2020
Conference Location
San Diego, CA
Conference Title
SPIE Optics Photonics 2020 Digital Forum
Pub Type
Conferences

Download Paper

https://doi.org/10.1117/12.2568502
Local Download

Keywords

Kramers-Kronig, reflectance, transmittance, spectrophotometry, refractive index polydimethylsiloxane, PDMS
Spectroscopy and Optical physics and communications

Citation

Czapla, B. and Hanssen, L. (2020), Direct method of extracting complex refractive index from routine Fourier transform infrared reflectance/transmittance measurements, SPIE Optics Photonics 2020 Digital Forum, San Diego, CA, [online], https://doi.org/10.1117/12.2568502 (Accessed October 27, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created August 19, 2020, Updated November 9, 2020
Was this page helpful?