We’ll begin by setting up a TIR model.  You can open the attached file “TIR_NSC_example.ZMX”, which can be downloaded from the last page of this article, to begin this example.  If you’re going to type the file in by hand instead of loading the attached file, you’ll want to first put ZEMAX into Non-Sequential Mode, and then you’ll want to check the Wavelength and General values (found in the System section).  Here are the values I’m using:

Object 1 is a “Rectangular Volume” made of silica, measuring 50x50x100mm. To create this object yourself, type in the following values:

Comment: Top Slab
Material: SILICA
X1 Half Width: 25
Y1 Half Width: 25
Z Length: 100
X2 Half Width: 25
Y2 Half Width: 25

It will also help to right click on Object 1, and then click on the “Draw” tab, and change the Opacity to 10%.

Object 2 is a “Source Ellipse” placed inside of the first block of Silica and aimed at a 45-degree incidence angle at the bottom face.  To create this object yourself, type in the following values:

Comment: Source
Ref Object: 1
Inside Of: 1
Y Position: 5
Z Position: 20
Tilt About X: 45
# Layout Rays: 20
# Analysis Rays: 100000
X Half Width: 10
Y Half Width: 10

Object 3 is a “Detector Rect” placed at the back end of the silica slab. To create this object yourself, type in the following values:

Comment: top slab det
Ref Object: 1
Z Position: 75
Material: ABSORB
X Half Width: 25
Y Half Width: 25
# X Pixels: 500
# Y Pixels: 500
Color: 2

The NSC Shaded Layout for this set of objects is shown below:

The NSC Shaded Model settings for this layout are as follows:

Clear the detector and trace rays (We need to make sure that the “Split Rays” and “Ignore Errors” boxes are checked every time just before we trace rays in this demonstration).  You’ll find that 100% of the light is internally reflected and hits the detector.