The final technique we will discuss is making up a complex geometric source model. This is a "mini-model" of the source, and uses the geometric sources supplied with ZEMAX along with a series of other objects intended to represent the internal construction of the source. For example, look in the folder {zemaxroot}/samples/non-sequential/sources/led_model.zmx:



This object is made up of a series of smaller internal objects:



which can represent the LED die, electrode wires, mounting points etc. Then detailed optical properties can be applied to the faces of the various objects, and then a large number of rays traced.

These source models can be traced directly, or the rays produced can then be saved to a ray database. In the ray database viewer (Analysis > Database > Ray Database Viewer) you may select a test object, and save all rays that land on that object as a new source object. This new datafile can then be read in using a source_file object.



Complex geometrical models suffer from one big problem: you need to know what values to enter! For example, what scattering function should be used on the electrode wires? What is the reflectivity of the support structure? This kind of data is not easy to obtain. Finally, the complex model must be validated against experimental measurements: which begs the question, why not just use the experimental data in the first place?

Generally speaking experimental data is more accurate and easier to work with. But in some systems, especially where light from the source is re-imaged onto the source, the effort required to construct a good complex source is worth it. It is also possible to get the best of both world, by defining a complex object, but to launch rays initially from a measured source file:


This figure is copyright Radiant Imaging and is used with permission.