Hold on a minute..... I said HPS, not HID....
As for MH lamps
So I was not 100% wrong (@stickstoungeoutatFishcake.com)
Yahoo! GroupsHigh pressure sodium lamps don't emit UV at all because excited
sodium atoms dont emit in the UV range.
Low pressure sodium lamps emit 99.5% of their light at exactly 589nm
and 589.6nm (yellow). But as you increase the pressure, the bands do
widen so a high pressure lamp emits some light down to just below the
500nm mark and right up into the infra-red. But no UV.
As for MH lamps
Metal halides are basically
high pressure mercury vapour plus metal iodide compounds, like thallium,
sodium, indium, lithium etc, - so you get (depending on the actual
metal iodides added) lots of spectral lines in all sorts of different
colours which add together to make what looks, to the eye, like a
really nice "sunlight" white (although in fact it is ever so spikey!)
and which has all the typical mercury vapour spikes too. So yes...
you get mercury vapour emissions at all the typical wavelengths. But
as you say, the manufacturers use glass that blocks the UV, probably
also UV blocking coatings, and possibly phosphors too to convert the
UVC to more useful visible light.
So I was not 100% wrong (@stickstoungeoutatFishcake.com)