Geometry
Insert the prepared geometry sequence from file. See Appendix — Geometry Instructions of the tutorial for the Double Gauss Lens in the Application Libraries for details on how to create the lens geometry.
1
In the Model Builder window, under Component 1 (comp1) click Geometry 1 .
2
In the Settings window for Geometry, type Double Gauss Lens in the Label text field.
3
In the Geometry toolbar, click Insert Sequence .
4
Browse to the model’s Application Libraries folder and double-click the file double_gauss_lens_geom_sequence.mph. Following insertion, the lens prescription details will be available in the Parameters 1: Lens Prescriptions  node. In addition, all expressions in the Parameters 2: General node can now be evaluated. The beginning of the lens prescription parameter list should now look like the following:
5
In the Geometry toolbar, click Build All .
6
Click the Orthographic Projection button in the Graphics toolbar.
Orthographic projection shows all objects as their actual size regardless of their position in the Graphics window. The alternative, perspective projection, causes more distant objects to appear smaller to give a more realistic 3D appearance.
7
In the Graphics window toolbar, click next to  Go to Default View, then choose Go to ZY View . This will orient the view to place the z-axis (optical axis) horizontal and the y-axis vertical as shown in the following figure:
Geometry sequence for the double Gauss lens. Light propagates from left to right (in the positive z direction) through the lens.
The geometry dimensions shown are in millimeters; this was automatically changed to match the length unit of the imported geometry sequence.
A Note on Parts and Part Instances
The geometry sequence setup was omitted from these instructions to save time, but it is worthwhile to view the geometry nodes in the Model Builder to observe how this geometry sequence was created.
Under Global Definitions  > Geometry Parts , two part definitions have been loaded: the Spherical Lens 3D  and the Circular Planar Annulus . Then under Component 1  > Geometry 1 , a number of part instances have been created.
Each part instance calls one of the part definitions, functioning as a subsequence of geometry instructions with various input parameters. For example, the Spherical Lens 3D part accepts input parameters for the radii of curvature of the surfaces, the lens center thickness, and the surface diameters, and then uses this information to construct a lens.
Parts are used heavily in optical simulations with the Ray Optics Module because they make it easy to load a standard lens prescription into the geometry sequence.