Rays can only enter a NSC group through the entry port.  NSC groups are first defined by inserting a Non-Sequential Component surface at the desired location in the LDE.  This is performed by simply changing the Surface Type in the Surface Properties dialog for the selected surface.





It is the Non-Sequential Component (NSC) surface in the LDE which describes the location, size and shape of the entry port into the NSC group.  The entry port may be planar, spherical, or conic aspherical, if desired, as described by the Radius and Conic parameters of the NSC surface.  The location of the vertex of the entry port (or NSC surface) is determined by the previous surfaces in the LDE in the usual sequential, local coordinate system.

The NSC surface also supports a surface aperture, and any rays which fall outside of the defined size of the aperture will be terminated.  Those rays pass through the apertured entry port will be traced non-sequentially through the objects defined within the NSC group (more on this later…).



3D Layout:  Note the rays which fall outside the defined aperture on the entry port are vignetted and are not traced within the NSC group.