In most optical designs, the exact representation of light sources plays an important role. One possibility for light source modellingare is rayfiles from Lumileds LED. Rayfiles represent the emission of the light source by a large number of rays without needing to model internal components. Each ray is described by three starting and three propagation coordinates, as well as power: (x, y, z, l, m, n, F).
The LUXEON Rebel Color Line has leading light output, color stability, flux density and clear saturated colors. These color LEDs are ideal for a wide variety of lighting, signaling, signage and entertainment applications.
- Download its raydata file from the website
https://www.lumileds.com/support/design-resources/optical
In this example, we will download the data for the ” LXML-PB02”. The ray file is available in several data formats. Click on the link to the ray file in compatible OpticStudio format. Next, read and agree to the disclaimer, then “Save” the file to your computer.
The ray files provided are only exemplary and imply the typical emission characteristic of this LED type. For this reason, the files provided do not guarantee that a LED which has been delivered shows exactly the same emission characteristic indicated in the ray file package.
- Content of the package
They are provided in a binary data format specific to OpticStudio with file extension .DAT. The rays in the ray file are randomly ordered. The starting point for all rays are slightly above the outer shell surface of the LED. If not intended otherwise, the starting points of the rays need to be specified in air.
The CAD model is provided in three different formats; STEP, IGS and SLDPRT. It is a placeholder for mechanical design only and not intended for optical raytracing calculations. CAD models and ray files always share the same coordinate system.
Importing ray files of a Monochromatic LED
In this example, we use ray data of the “LXML-PB02. It is a monochromatic LED with its spectrum centered at approximately 470 nm and a spectral width of ~ 23 nm.
The OpticStudio sample file (named *_sample_Zemax.zmx) includes the CAD model and the ray file positioned at the global origin. It comprises all recommended settings and provides an easy to use starting point for an optical raytracing calculation. Therefore, it is only required to copy the necessary files in the certain data folders of OpticStudio and to open the sample file.
Here is the 3D geometry of the two objects displayed in the NSC Shaded Model viewer. The rays are starting close to the outer shell of the CAD model.
In the System Explorer, the units are set to “Lumen” and “mm.” If not intended otherwise in the pdf documentation, units in the OSRAM Opto Semiconductors ray files are mm. The luminous flux of the GB DASPA2 is measured in units of Lumens so we choose that unit for this simulation. Illuminance is therefore measured in terms of lm/m2, or Lux. Luminous intensity is measured in Lumens/Steradian or Candela (Cd). Luminance is measured in lm/m2/sr, or Cd/m2, which is sometimes referred to as a Nit.
The CAD model shares the same coordinates with the ray source but the coordinates are not linked. As the CAD model is for reference only, it will be ignored in the raytrace. This option for the CAD model is set in the object properties under Type…Raytrace by selecting “Rays Ignore Object = Always.” of the CAD model. However, the rays in the ray file start outside the CAD model, such that it is possible to, for example, allow the LED surface scattering properties in order to consider light back-reflected from secondary optics to the LED and again backscattered from the LED towards the optics.
Radiation Pattern Characteristics
