So, if a
Mercury Vapor black light is just a lamp with a
woods glass filter built in. What's the difference in output between that and throwing a
woods glass filter on a Source4? Does a
Mercury Vapor lamp put out more UV than a
HPL 750?
Simple answer, yes.
Arc source lamps put out a
broad spectrum of visible and invisible UV & IR light due to the arc going
thru them. A very
broad amount of light centerd around what gasses are used to maintain or stabilize the arc of light.
Sodium Vapor lamps for instance will have very limited amounts of UV light but high amounts of IR light.
DUV 35 Philips#29345-6(293451)
HID, SE. MPXL HR. (High UV Output) 35w/85v T-10.7mm 3.8mm
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HPA 400SE Philips #198228
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This types of light having a lot of UV includes
fluorescent,
mercury vapor, xenon and high
intensity discharge lamps. (Though
HID lamps are a mixture of gasses including sodium and mercury normally optimized to provide most of the light in the visible light spectrum.)
Dependant upon what type of discharge lamp it is, much of the light isn't even in the visible spectrum of light - this especially with
mercury vapor or
mercury vapor based
fluorescent lamps. The arc or lightning within the glass tube is so intense that it's beyond one's ability to see it. Think of welding - you would tend to go
blind if in arc welding you didn't have a special viser. That's the same type of light output in most arc source lamps esepcially in an un-filtered xenon,
HID and
Mercury Vapor source. This verses say brazing where a less intensive visor is necessary might be say a
sodium vapor type of arc as opposed to xenon gas maintained arc of light. The rest of the arcs for the most part fall in between these types that is closely linked to
color temperature.
Now think
color temperature of most arc lamps or the range of color temperatures about 1,6K to 7,2K of arc lamps verses that 2,6K to 3,5K range of
color temperature to that of a
filament lamp. If the nm scale of UV light or magnetic spectrum doesn't mean much at this
point, think
color temperature instead and you will get some similar sense of what UV is in output. Not the same scale but both having some simularities. A un-color corrected
incandescent lamp cannot do 7,2K - the
filament burns up at around 3,5K. You can color filter/color correct to 7,2K but in doing so the amount of useful light given white light is a bell curve of all light - just more in the center than toards the edges, that light not blocked or filtered in absorbsion that would be 7,2K is very limited. Same with UV output out of a
incandescent or taken for example
HPL source. Yes, you can install a UV
lens into a
Leko, output of UV light would be about in the couple of
candlepower range however once all other light was blocked out. Perhaps as a rough guess, you would have a 250
candlepower UV light output.
Coated phosphor coated arc source lights such as most fluorescents and
mercury vapor lamps, or such light fixtures normally light by way of the UV light discharge from the arc, heating up the phosphors coating the inside walls of the lamp which incandescess by themselves not by way of the arc to provide the light. Note the greenish hue to often older phosphor coated school classrooms. That's a
CRI or color
rendering index question that's another topic but it's having to do with the phosphors used and or the amount of spikes of energy within the visible light spectrum which is useful as to how true to 100% sunlight and
incandescent lamps that arc source spectrum of light is. Such phosphors in a normal arc source lamps coating also
block out the often harmful UV output from the arc. Other types of arc source lamps have a more mid range visible light spectrum of light and filter out the UV and even IR light. UV Measured as: irrad at 0hr µW/cm Square. nm = Nanometer - A
unit of wavelength equal to 10-9
meter. There is no conversion chart of specific conversion between
color temperature and UV output - it's only a related scale.
On special coated UV lamps, the phosphor coating is replaced by a glass (above) or coating which blocks the harmful UV output, passes the UV-A black light output and to some extent - especially with black light blue
fluorescent lamps, outputs a blue/purple light that's more visible and often more associated with black light output but really is not. Diazo lamp UV radiation is also to some extent useful. Rephography (sun tan) lamps are also good UV-A along with UV in general sources of light. These types of lamps as opposed to UV type lamps also let pass the more dangerous UV-B and UV-C light
thru them. In other words, they will allow your UV paint to glow and let you get skin cancer and a tan at the same time. All of this is also distance based - the further away you are, the less the longwavelengths of UV light will
effect you. It's a concept to use a Diazo or Rephotography lamp once filtered or lensed also as a UV lamp and in fact, some types of UV
fixture use such lamps as a HPA Metal hallide arc source lamp. The 320nm range is what many tanning lamps will most operate at but they also have lots of other UV light output. I
stock some tanning lamps that are also used in UV fixtures.
You can get UV lamps including the sandard 48" ones either way - Black
Bight, or Black Light Blue. On a true black light lamp, you won't see a blue output unless some of the UV light is passing
thru lenses or partially stopped by the glass. This will appear to some extent blue/purple but there will be no observable light output other than in
reflection of what phosphors react to the light.
An arc source lamp is different than that of a
filament lamp.
HPL lamps and all
filament lamps, instead of having an arc that provides the light, they have a resister coil of
tungsten and other compounds doped into them which resists the flow of
current and sort of burns up by way of amperage running
thru a
wire with lots of resistance or is resisted in burning up to the extent of this resistance is turned to heat and the metal gets hot enough it incandescesses. Such burning of the metal - literally getting beyond red hot into white hot than provides light in much the same way as you can see not by the flames once they burn down but late at night by way of the coals of a fire place glowing. Those coals still glowing are similar to the metal of a
filament resistant to the
current flow. Most of the resistance is turned into heat with only some of it in output by way of the visible light spectrum just as an arc source provides most of it's output in other than visible light but a much more efficient amount of it.
That visible light / heat / light waves is part of the electromagnetic spectrum. About 380nm for violet to 770nm for red in wavelength. IR light is in the 770 to 1106 nm range and cannot be seen by the human eye but can be sensed by heat on the skin. UV light is in the 100 to 380nm range. It's further broken up into UV-A in the 315 to 400nm range (this is the useful UV light), UV-B 280 to 315nm and UV-C 100 to 280nm all useful for sun tanning lamps and or that cause skin cancer. The warnings on moving lights are due to UV B & C output of the lamps. This UV output normally effects the phosphors of a
fluorescent lamp or coated
mercury vapor lamp that convert unseen UV light into light from the visible spectrum, or the phosphors of a UV paint that do the same. UV is sort of a long wavelength light, IR is a short wavelength heat which can also be transformed by way of such things as the inner capsules on say a CDM type lamp where the
ceramic capsule gets so hot that it glows in a way similar to a
tungsten filament glowing. This is by me not much studying it yet - converting high wavelength IR light into visible light.
HIE150w/U/BDX Venture #33051 Blue SE. MH.
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Ballast + Ign) Any Burn Pos. 462nm 5,000hr
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HID Enclosed Fixt 46% Satur. 150 w E-54mm
LCL 89mm E-27 (HPS
Ballast + Ign) Any Burn Pos. 535nm 5,000hr
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LCL 7" E-39 (M59) Univ. Burn 635nm 5,000hr
MHL-250 Ushio #5000089 CL. DE, MH,
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MOL 68mm R 7s UV-Housing Only, (Spect. Rng. 300-450nm) 500hr
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Fluorescent 380-420nm 40w/101v T-40.5mm
MOL 1,213.6mm G-13 Diazo Copy/Aquarium/Phototheorpy Diazo 9.2w UV-A 0.35w 15%=2,000hr
F40T10BLB Ushio #3000138
Fluorescent Black Light Blue 39.5w/106v T-10
MOL 47.17" G-13 UV-A - 368nm UV-A 8.1w 5,000hr
TL 40/08RS Philips #928011300800
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F40T10BLB Ushio #3000138
Fluorescent Black Light Blue 39.5w/106v T-10
MOL 47.17" G-13 UV-A - 368nm UV-A 8.1w 5,000hr
Glass, plastic and other coatings normally absorb the long wavelength UV output of lamps thus my warning about tube guards in it being possible that a tube guard on a black light
fluorescent lamp, could be limitating the output - this as with various lenses unless of those glasses and or lenses specifically designed to let pass the UV wavelength. Don't know much about "
woods glass" it's a term I have heard before, but this would be assumed to be a type of glass that lets the longwave UV light pass without much
blocking of it. Suprasil quartz is another type of glass that allows UV - that's also useful for xenon lamps in output to produce UV and in general allow for extra light. The lenses of a standard
Fresnel,
Leko or
PAR would tend to
block UV output, just as with most
mercury vapor lamps, the only lamps permissible to be used in open fixtures (those without lenses) are the coated ones.
Clear Mercury vapor lamps would be harmful in an open
fixture.
(note also mention of wavelengths, TV, radio frequency,
X-Rays etc. are also wavelengths of short of long type - visible wavenghts of light or those associated with light are within the same type of radiation.) Theater is science! Study Science and you master Theater.
Incandescent lamps do have a certain amount of UV output. A
HPL lamp by itself will tend to have the harmful effects such as fading or discoloration on things like paintings and even tanning people given time, however this output is very limited, and normally the UV output is blocked by the lenses and color filters. MR-16 type lamps that have lenses often will also be "UV-Block", "UV-Stop", "UV-Cut" or "UV-Control" dependant upon what term is chosen by the manufacturer. This
lens by itself blocks/absorbs some of the UV output, and often will have a special coating on it to further absorb the UV output. Such coatings are also used on arc lamps at times especially if a
clear lamp making use of the small arc gap for control of the beam of the light or in having a fairly exposed beam of light without much by way of lenses or filters. The amount of UV output of a
filament lamp is very limited.
Filament lamps provide most of their light in the visible spectrum of light by way of a bell curve which doesn't have much light falling outside it and into the UV spectrum of light. There is some UV light output, but not a huge amount. See the Violet to Red nm scale above, than fill in your ROYGBV color spectrum to that visible spectrum of light. Most of the light produced by a
filament lamp is withing the bell curve with only limited amounts of light outside the visible spectrum of light. There is a long way to go before the seemingly "blue/white" light of a
HPL lamp gets into the UV range of light. It will have more UV light than say a
incandescent lamp, and much more than say a candle but not nearly as much as a
fluorescent or normal UV source of light. Even the
incandescent black light party bulbs are more purple bulbs than real UV output lamps. There might be some filters and coatings to boost the UV output but not enough. IT's more a party
bulb in providing the blue/purple light most associate with UV but not much in making phosphors glow.
Distance and the
law of squares also has an
effect on UV output - in other words, the further away, the less UV output - especially from a
incandescent source of light. A primary other purpose of a
fixture that has a
reflector being more efficient than that of a
fluorescent lamp is that the beam of light is reflected in a specific direction thus more efficient. Sort of the same question of using a
Leko over a
scoop or bare light
bulb on
stage. If you want to direct your light as opposed to
wash it, a UV
fixture will be more efficient by way of optics - beyond any lamp to lamp comparisons.
