So far, we have developed a geometry in which we have a nominal position and the ability to tilt the mirror about the nominal position. By simply entering data into the x-tilt of surface 3, or using Tools > Slider, we can produce any scan agle we want. But, for optimization and tolerancing purposes, it is useful to sample this continuous movement by defining a number of configurations. This technique allows us to define a number of fixed-scan angle systems, as a way of modelling any scan angle.

Let's say we want to model scan angles of ±5° about the nominal 45° position. Click on Editors > Multi Configuration Editor, and from within the Multi-Configuration Editor click on Edit > Insert Configuration twice, so that you have three configurations. Double-clcik on the left-most column of the editor, and tell ZEMAX to make Parameter 3 of surface 3 a multi-configuration parameter, then edit the values as follows:

In this way, only the parameter in the multi-configuration editor is different between configurations. All other parameters are the same, except where they pick-up from a parameter controlled by the multi-configuration editor.

Set the 3D layout controls as follows:

so you can see all three configurations superimposed. You can see that the mirror is now scanning about its front vertex, similar to a galvanometer mirror.

The configuration can also be changed by hand by pressint cntl-A from the keyboard. Note as you do so that the semi-diameter of the mirror, lens and image surfaces all change as the configuration is changed. This is because semi-diameters are computes as 2mm + whatever the illuminated region is. ZEMAX automatically set the semi-diameter of a surface to be the largest of whichever configutation is biggest. This is done by double-clicking on the semi-diameter of a surface and choosing the "Maximum" solve.

Now this lens was originally optimized for on-axis performance only. It is now being used effectively with ±5° field points, and so should be re-optimized. Open the merit function editor, and press Tools > Default Merit Function, configure it as follows:


Re-optimize the lens and ZEMAX quickly produces a new lens that minimizes the spot size in the scanning system. This file is saved in the attached zip archive as galvanometer.zmx