ABCD
The ABCD surface provides a powerful method for modeling "black box" optical systems. If you have a lens (or a complete optical system) which is only a subsection of what you wish to model, and you do not have prescription data for the individual components, you can still model the behavior to first order.
The ABCD surface accepts eight parameters: Ax, Bx, Cx, Dx, Ay, By, Cy, and Dy. These are used to form two- by-two matrices (one for the x-direction and one for the y) which are used to alter the ray as it crosses the surface. The exit ray is related to the incident ray by
with a similar expression for the y components. Because there is no reliable way to compute the phase through an ABCD surface, any calculation that requires OPD data, such as OPD fans, MTF, and Zernike coefficients, will not be supported if an ABCD surface is present in the lens description.
PARAMETER DEFINITIONS FOR ABCD SURFACES
| Parameter # | Definition |
|---|---|
| 1 | Ax |
| 2 | Bx |
| 3 | Cx |
| 4 | Dx |
| 5 | Ay |
| 6 | By |
| 7 | Cy |
| 8 | Dy |
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