On Thursday, June 21, Mark Nicholson, vice president of the Zemax Group at Radiant Zemax, presented a Webcast entitled "Speed product development with innovative illumination design software." The presentation included an excellent description of the obstacles solid-state lighting (SSL) product developers face when working with LED sources.
The Webcast, still available at the above link, also covered modeling software that uses ray-tracing technology that SSL developers can use to accurately predict product performance without building expensive prototypes. Radiant Zemax has an extensive set of precision models for readily-available packaged LEDs.
The early part of the presentation revealed that while LEDs seem like a relatively simple source, they are actually much more complex than legacy sources. Different LEDs provide vastly different light patterns.
Nicholson showed a photo of an LED in the on state, and the source looks like a fairly uniform one. In reality that's not typically the case and the irregularity can greatly impact end SSL products.
For example, Nicholson showed a close up, magnified image of a widely-used LED in the on state. The brightest areas were at the edges of the package as opposed to the center.
Nicholson also showed a photo of a multi-emitter RGBW (red, green, blue, and white) packaged LED array. The domed lens used in the package resulting in a distortion of the shape of the individual emitters – especially in the center of the array. You can see the distortion when the LED is in the off state, via a close-up photo looking into the dome. The distortion is evident in the projected light when the LED is turned on.
If you missed the Webcast, register and take a quick look at the archive. You will learn about the basics of light-modeling software, and you will learn quite a bit about LED sources.