The NSC surface has a total of 9 parameters, most of which are used to define the location of the exit port with respect to the entry port.

• Draw Ports?:  This flag is used solely for drawing purposes.  Sometimes, it is useful to be able to display the entry and exit ports in the layout plots.  Use 0 to draw neither the entry or exit port.  Use 1 to draw just the entry port, 2 to draw only the exit port, and 3 to draw both.  The default value is 3.
• Exit Loc X, Exit Loc Y, Exit Loc Z, Exit Tilt X, Exit Tilt Y, Exit Tilt Z:  These parameters describe the x,y,z positions and tilts of the exit port surface with respect to that of the entry port.  As an example, if only a Exit Loc Z of 10 was specified (all other location and tilt parameter = 0), then the exit port would be located 10 lens units along the local z axis of the NSC surface (the entry port):

ZEMAX uses a default Exit Loc Z value of 1, simply to place the exit port some non-zero distance from the entry port.  If the two are co-located, then rays which hit the entry port immediately exit via the exit port, and will never see the objects defined within the group.

• Order:  The order flag indicates the order in which to perform the tilts/decenters.  This works identical to that of the Order flag for Coordinate Breaks.  For details, click here.
• Reverse Rays:  This flag is used to indicate the direction of propagation of rays once they leave the exit port.  If the flag is 0, then ZEMAX assumes that the non-sequential group acts like a refractive lens.  In other words, if the direction of propagation of the rays is the same from entry to exit port, then this flag should be zero.  If, on the other hand, rays reverse direction relative to the incoming direction, then this flag should be 1. 

Since the positions of the exit port with respect to the NSC surface are defined by the parameters of the NSC surface itself, the surface following the NSC surface in the LDE becomes the location of the exit port.  It is this surface which defines the size and shape of the exit port.  Note the Semi-Diameter of the exit port must be a user defined value, and cannot be automatically calculated.



Apertures may also be placed on the exit port surface, if the desired shape is non-circular.  When a ray strikes the exit port, the coordinates and direction cosines of the ray in the coordinate system of the exit port are computed, and then the ray is traced sequentially through any remaining surfaces defined in the LDE.  If one of the following surfaces is another Non-Sequential Components surface, then the process begins again for the components defined for that group.  This means that more than one NSC group may be defined, and each group has its own entry and exit port!