Gradient 12
The shape of the Gradient 12 is the same as the Standard surface, with media whose index of refraction is defined by:
The Gradient 12 surface type allows specification of dispersion properties using the complex Sellmeier dispersion that is defined in the sequential surface type Gradient 5. The same file used by the Gradient 5 surface, SGRIN.DAT, will be used in obtaining the dispersion coefficients.
The maximum step size, Delta T, determines the trade-off between ray tracing speed and accuracy. For details, please see the "Discussion on maximum step size for GRIN surfaces" and "Restrictions on surfaces following GRIN surfaces" under the Gradient 1 documentation.
The Order is the order of the highest polynomial constant (for x, y, and z) shown in the Lens Data Editor. The maximum is 20, which will show all constants as defined in the index of refraction expression above, as Parameters 4-63. Any constants not shown in the editor are assumed to equal zero. If this order parameter is zero, then all constants are zero and only the base index, n0, is available in the lens data editor.
PARAMETER DEFINITIONS FOR GRADIENT 12 SURFACES
| Parameter # | Definition |
| 1 | Δt |
| 2 | Order. The order of the highest polynomial constant (for x, y, and z) shown in the lens data editor. The maximum is 20, which will show all constants as defined in the index of refraction expression above. Any constants not shown in the editor are assumed to equal zero. If this order parameter is zero, then all constants are zero and only the base index (Parameter 3) is available in the lens data editor. |
| 3 | n0, the base index |
| 4, 5, 6 | c_x1, c_y1 , c_z1 (1st order coefficients) |
| 7, 8, 9 | c_x2, c_y2 , c_z2 (2nd order coefficients) |
| ... | ... |
| 61-63 | c_x20, c_y20, c_z20 (20th order coefficients) |
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