Cauchy
Cauchy’s dispersion formula: refractive index against wavelength as a constant plus terms in 1/x² and 1/x⁴. Use it for the refractive index of a transparent material measured at several wavelengths, for example with a prism or refractometer.
Parameters
- The index approached at long wavelengths.
- Coefficient of 1/x², in the units of x squared.
- Coefficient of 1/x⁴, in the units of x to the fourth power.
Tips
- This is the dispersion formula, not the Cauchy (Lorentz) probability distribution. For a peak, see Gaussian.
- B and C depend on the wavelength unit: B scales with its square and C with its fourth power, so record the unit with the result.
- If C is poorly determined, enter 0 as its Guess and check Fix to fit the two-term form A + B/x².