Something we probably should have done before deciding on the layout of the LED panel...

Luminus provides zemax ray spectrum files for their LEDs. So we were able to simulate the optical power distribution of our LED panel.

We had somewhat arbitrarily decided on the substrate to be at 10mm distance from the LEDs. Using the simulation this reveiled hot spots.

Simulating at increments of 1mm, a much more homogenous optical power distribution should be at 15mm.

The center still showed a hot region. Removing the center LED would fix this to some extend.

So we decided to implement these changes in the final design. In CAD we moved the entire LED panel 5 more mm away from the substrate plane. When ordering the LED panel, one should mark the center LED as do not assemble.