This is one of the individual LEDs from some "cool white" strip lighting sold by Inspired LED at Amazon.
These LEDs are covered with only a thin film of sealant, about 0.25 mm thick as measured by focus change from the surface of the sealant to the top layer of light emission.
In this image you can clearly see the individual grains of various colored phosphors used to fill out the spectrum from the blue light that's naturally emitted by the LED.
Shot at 20X and about NA 0.145, using a Nikon CF 20X NA 0.40 EPI ELWD stopped down by a 2.9 mm aperture in front of a 200 mm tube lens. 28 frames at 5 microns, StackShot, ZS PMax. LED dimmed to partial brightness using a 1K dropping resistor for the whole 21-LED strip. Shot with custom white balance based on diiffusing the LED through a piece of white paper. The color temperature is 4850 with a tint of +32, as reported by Adobe Camera Raw 6.6 and Canon T1i.
--Rik
