Virtual Rays Enlighten Lamp Designs

David Silverglate, Sky-Designs

To most engineers, light-emitting diodes (LEDs) seem rather simple, comprising a chip inside a plastic envelope with leads sticking out. When you apply current to one end, light comes out the other end.

In fact, LEDs are quite a bit more complicated. Determining and controlling the pattern of light radiation are difficult tasks. A typical narrow-beam device suffers a drop-off in brightness on the mechanical axis of the package. Also, a significant amount of the light flux is not captured in the desired narrow radiation pattern.

A good package design depends on the application, of course. One growing application trend is toward using efficient, narrow-beam LEDs that provide higher on-axis intensity. Traditional LED packages are often not adequate for this type of application because of the characteristics I have mentioned.

To illustrate a means of accomplishing virtual design improvements without mechanical prototyping, I used powerful photonics design software to model a traditional lamp, then made changes to improve its performance. The new design not only improves the nominal performance of the lamp, but also reduces the effects of manufacturing tolerances.