Sellmeier Equation

The Sellmeier Equation calculator computes the Sellmeier relationships between refractive wave index and wavelength based on the wavelength of a transparent medium and several coefficients.

INSTRUCTION:Choose units and enter the following:

• (λ) Wavelength
• (B₁) Coefficient
• (C₁) Coefficient
• (B₂) Coefficient
• (C₂) Coefficient
• (B₃) Coefficient
• (C₃) Coefficient

Sellmeier Value (n²): The calculator returns the ratio as a real number.

The Math / Science

The Sellmeier Equation is an empirical relationship between refractive index and wavelength for a particular transparent medium. The equation is used to determine the dispersion of light in the medium. The usual form of the equation for glasses is 

`n^2(lambda)=1+(B_1lambda^2)/(lambda^2-C_1)+(B_2lambda^2)/(lambda^2-C_2)+(B_3lambda^2)/(lambda^2-C_3)`, 

where:

• n² = Sellmeier Value
• `lambda` = wavelength
• `B_1` = Coefficient
• `C_1` = Coefficient
• `B_2` = Coefficient
• `C_2` = Coefficient
• `B_3` = Coefficient
• `C_3` = Coefficient

References

The formula and definition of the Sellmeier Equation are from Wikipedia (https://en.wikipedia.org/wiki/Sellmeier_equation).