here are a few shots from the funktional ring:

1% PWM - it wasn't possible for me to get a photo from a 100% referenz, because the picture was overall white :-D

left-side on 25% right on 2%

right-side on 50% left on 2%

As you can see, i think there is no diffuser needed, because at a distance of 10 mm and more no longer points of the LEDs can be seen