We have found some incredibly high color quality LEDs based on Red-Green-Blue phosphors pumped by near UV LEDs.
Currently, white LEDs can be made by several different methods. The most common method is to combine a yellow phosphor wavelength converter with a GaN blue LED chip. The blue light emitted from the GaN LED chip is partially absorbed by a yttrium aluminum garnet (YAG) phosphor and reemitted as yellow phosphorescence. Thus, “white light” is generated by the combination of these two emission bands.
However, there are also some problems with such “blue yellow” white LEDs including low color rendering properties and issues with non-uniform aging of the leds and angular color shifts from the leds.
These new chips we are investigating utilize a near UV LED at ~400 nm and a mixture of red, green and blue phosphors. Several different color temperature example spectra can be seen below.
As you can see, the 400 nm LED wavelength can shift slightly and different spectral shapes can be obtained by changing the relative concentrations of Red, Green, and Blue phosphors.
The output from these new LEDs produce a light output with CRI and CQS of between 98 and 99. Furthermore, these new LEDs have CRI R9 values of ~99 making them ideal for medical imaging applications and have one of the widest spectra from a single led making them uniquely suited for spectroscopy applications.
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