Skip to main content
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.

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

Keywords

Kramers-Kronig, reflectance, transmittance, spectrophotometry, refractive index polydimethylsiloxane, PDMS

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 July 2, 2022)
Created August 19, 2020, Updated November 9, 2020