LED is the thing of the future.
This one is cooled down by silicon oil that also make for a varied light and shadow. The LED can be moved into position and the fixture comes in many different versions. As seen at Zona Tortona today - look at Illumiluce
Some mysterious reason the impact of optical diffracting light in a small space between the bulb and the resin during the production process, and the resin shrinks slightly and space is created.
SvaraRaderaT5 Grow Lights
That is soooo over my head...
SvaraRaderasorry - teach me !