Optimize the system for best focus using the RMS Spot Radius default merit function.

After optimization the variable in the editor, the thickness of surface #2, will be close to 51.608 mm.

The longitudinal aberration plot under Unalysis>Miscellaneous>Longitudinal Color shows significant amount of longitudinal color abberation.

We will now add some diffractive power to the Binary 2 surface.

Open the Extra Data Editor and set the following parameter values and set the coefficients of r^2 and r^4 as variables..



Re-optimize the system.

Notice that the longitudinal color is now much smaller than before.