Gradient 4
This surface has the same shape as the Standard surface, with media whose index of refraction is described by
Eight parameters are required: the maximum step size, Δt, the base index, n0, and the remaining six coefficients of the preceding equation. Note that some of the coefficients have units. This particular GRIN model is useful for gradient index optics with a cylindrical power profile. It is also useful for modeling thermal gradients in optical elements, if you have sufficient data to compute the coefficients.
The linear transverse terms, nx1 and ny1, are ignored when performing paraxial ray tracing.
The maximum step size Δt determines the trade-off between ray tracing speed and accuracy. For details see "Discussion on maximum step size for GRIN surfaces". Also see "Restrictions on surfaces following GRIN surfaces".
PARAMETER DEFINITIONS FOR GRADIENT 4 SURFACES
| Parameter # | Definition |
| 1 | Δt |
| 2 | n0 |
| 3 | nx1 |
| 4 | nx2 |
| 5 | ny1 |
| 6 | ny2 |
| 7 | nz1 |
| 8 | nz2 |
Next: