In this technical guide, we apply some new techniques to these sources and introduce some alternative sources as well. We also cover some specialty topics and discuss multiple sources and wavelengths. This technical guide addresses the following topics: 1 How to input rays one at a time Inputting rays is useful when you know the exact location and direction of the rays you want, or have a large file of rays to import. 2 Using the BRO Light Source Library The BRO Light Source Library, available to ASAP customers with current software maintenance agreements, is a growing collection of more than 150 U.
S. and European source models that can be imported directly into ASAP projects. The library includes filament, light-emitting diode (LED), arc, and cold cathode fluorescent (CCF) sources. These sources include detailed geometry and produce near- and far-field patterns that are in agreement with measurements. We will show you how easy it is to use, and the various ways you can use it. 3 Using Radiant Sources These are source files created by Radiant Imaging, Inc. for a special source you may need to analyze in your system. The distribution file should be obtained from Radiant Imaging (http://www. adimg. com/) in the ASAP format for distribution files.
Apodizing in ASAP means making changes in the spatial or angular distribution of the rays from a source. This is accomplished by applying your own measured data or a function, using several approaches that are available. We will discuss each of these and give examples. 7 Originating sources in a medium Since the default medium in ASAP is VACUUM/AIR, it is also assumed that the rays of a source will begin there as well. However, an application such as an LED source may require something different. We will show you how to change the medium where the rays begin. 8 Multiple sources and multiple wavelengths
You need to understand how to set up multiple sources at different wavelengths, so that ASAP makes the proper refraction or Fresnel calculations in your model. 9 Controlling the flux with the command language When setting the flux of multiple sources, there are certain things to be aware of. We will discuss the FLUX command in combination with SELECT ONLY, and show how to change the default name for the units of the radiant power. O n e r ay a t a t i me ASAP offers two methods for entering individual rays. Each has its particular uses, depending on the application. You need to decide which one is best for you.
The first method uses the command, RAYSET. This command can take many arguments, but at a minimum, requires supplying the locations of each ray. If you use RAYSET for a coherent source, you may also add beam shape and complex amplitudes. Its use as a coherent source is part of what makes this command unique. The other is the fact that the given rays must reside on a single plane like a grid source. The first argument tells what plane the rays will originate from and the next one gives the position of the plane on that axis. The coordinates and other data for each ray follow one line at a time.
The following example gives ray positions only, and plots the ray positions with the SPOTS POSITION command: 8 ASAP Technical Guide—Sources SOURCES IN ASAP NOTE: The short form of this command, RAYS n, is used to reset the total number of rays in storage to n, the first n rays currently in the virtual. pgs file. RAYS 0 is often used to discard all the current rays. RAYSET or RAYS, by itself, restores all the rays from the current virtual. pgs file. For large sets of rays, these lines (even including the RAYSET command) could be input from another file, using the $READ command.