The goal of this project is to create a white light source with a uniform spectral output. Due to size and power constraints, LEDs are the preferred light source. Starting with a combination of white and warm-white LEDs, additional colors are added to fill in gaps in the spectrum. However, after exhausting all standard LED colors of suitable brightness, some gaps still remain. To fill in these final gaps, UV LEDs coated with various fluorescent inks were tested, which showed great potential. However, available fluorescent ink/dye technology proved inadequate to our needs, thus we are seeking alternative fluorescent coatings, chemistries or materials. An alternative approach would be to locate an LED manufacturer or supplier who could coat the InGaN UV chip itself with a fluorescent layer (similar to the approach of coating a InGaN blue chip with a yellow fluorescent phosphor layer to produce a white LED). However, this would need to be done with relatively low quantities of LEDs, approximately 500 to 1000 pieces, without incurring a high NRE. Based on the combined spectral output of the LEDs we have now, at least two additional fluorescent/UV hybrid LEDs would be needed.

The intended application would be as part of a small, low power broad-spectrum white light source used to illuminate small areas as part of a machine vision & test/measurement system. The total number of LEDs used is 8 to 12, including white and warm white LEDs, several LEDs of common color, and two or three of the fluorescent/UV hybrid LEDs we are seeking to produce.