Sellmeier Equation Calculator

Created by Dominik Czernia, PhD candidate
Last updated: May 30, 2022
The Sellmeier equation uses the Kramers-Kronig relationship between optical absorption and refractive index to calculate the wavelength-dependant refractive index based on constants relating to key absorbance. Fill in the Sellmeier coefficients for a given substance in the blue boxes, along with a wavelength of interest, and the refractive index will be given in the orange box. The sellmeier "B" coefficients are the oscillator strengths of transitions, and the "C" coefficients are the squares of the respective transition energies (as photon wavelengths). Thus, knowing the experimental or calculated absorption spectrum of a substance, it is possible to predict the refractive index.
Dominik Czernia, PhD candidate
Wavelength
μm
B1
B2
B3
C1
μm²
C2
μm²
C3
μm²
Refractive index (n²)
Refractive index (n)
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