Set the following system parameters

System unit to mm (System > General > Units)
Wavelength to 0.550um (System > Wavelengths)
Set one field with values X=0 and Y=0 (System > Fields)
Set system aperture as Entrance Pupil Diameter of 100 mm (System > General > Aperture)

Enter the following surfaces in the Lens Data Editor. The image surface has a user-defined semi-diameter of 15 mm (U next to the column).



The "sag" or z-coordinate of the standard surface is given by:

where c is the curvature (the reciprocal of the radius), r is the radial coordinate in lens units and k is the conic constant. The conic constant is less than -1 for hyperbolas, -1 for parabolas, between -1 and 0 for ellipses, 0 for spheres, and greater than 0 for oblate ellipsoids. To make the mirror surface parabolic, enter the conic of -1.

Since the focal length of a mirror is half the radius of curvature, enter -2000 mm in the Radius column. The sign of the radius of curvature is negative since the center of curvature is to the left (toward -Z axis) of the mirror.

Since surface #1 and the image surface are co-located, we will choose not to draw the surface #1 in the layout so that we can see only the image surface at that location.

Set the following property in the surface property window.



To make the mirror substrate flat and orthogonal to the optical axis, choose the following options in the surface property window. We will chose the thickness of 40 mm since the manufacture does not specify the substrate thickness on their web site.



Open the 3D layout with the following settings.