Sellmeier Equation calculator
n(λ) using a 3-term Sellmeier expansion (BK7-style coefficients by default).
Category: Materials
Formula: n² = 1 + Σ Bi·λ²/(λ² − Ci)
Inputs
| Input | Parameter | Unit | Default |
|---|---|---|---|
| Wavelength | lam | µm | 0.5876 |
| B1 | B1 | 1.03961212 | |
| C1 (µm²) | C1 | 0.00600069867 | |
| B2 | B2 | 0.231792344 | |
| C2 (µm²) | C2 | 0.0200179144 | |
| B3 | B3 | 1.01046945 | |
| C3 (µm²) | C3 | 103.560653 |
Result with the default inputs
- Refractive index n: 1.516798
Open it with your own values: put each input in the address as a parameter, for example /calculators/sellmeier-equation?lam=0.5876. A unit other than the listed one goes in <parameter>_unit.
Read more: Wikipedia: Sellmeier equation