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ultra violet

Discussion in 'Lighting and Electrics' started by freddy, Aug 23, 2003.

  1. freddy

    freddy Member

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    I need to create a heavenly look for a show, ie white blinding light etc, so im thinking uv guns and white costumes/setting etc...Does anyone have any idea how these will mix in with the other lights, i mean will i lose the effect as i light more and more of the scene...also, what is a good additive for costumes/ cloths to bring out the glow, i know detergents can be good.
  2. TechDirector

    TechDirector Active Member

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    South Florida, USA
    What are "uv guns"? Ultra Violet guns? Wouldn't that give the audience cancer? lol j/p! I once saw this show on broadway called "ballet tech" and for one skit they called it "behold, man" and they had a huge white sheet of cloth (silk like) suspended beneath the lights. and each of the four corners were connected to 2 pulleys on two seperate flys. And from the pulley's, a string hung down so that 4 techie's on all 4 corners of the stage could slightly move it, creating a cloud effect, and all you could see was the guy dancing around. Keep in mind that it covered ALL the lights. It was really a nice effect. In the background they had a white scrim, and they used their color strip lights (you know those lights that have the colored gels that are on a strip and there are like 7 or 8 or them in a row). Well they took out all of their gels and tilted it so that it was shining all the way down the scrim. It was really bright.

    I don't know if this can help you or not. Just suggestions. What's the show called?
  3. ship

    ship Senior Team Emeritus Premium Member

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    Ultraviolet (UV) Radiation: Radiant energy in the range of about 100-380 nanometers (nm.) For practical applications, the UV grand is broken down further as follows:
    Ozone-producing 180-220nm
    Bactericidal (germicidal) 220-300nm
    Erythemal (skin reddening) 280-320nm
    “Black” light 320-400nm
    The International Commission on Illumination CIE defines the UV brand as UV-A (315-400nm;) UV-B (280-315nm) and UV-C (100-280nm.)

    More and more people are watching television and computer screens every day. The cathode-ray tubes that form these screens emit not only visible light but also a good deal of ultraviolet and even “soft” (i.e., relatively low energy_ X-rays. Distance lends some safety. The X-rays and most UV are absorbed by a couple of feet of air. Any kind of eyeglasses, even those with nothing but windowpane glass in them, will also block out the UV. Increasingly, opticians are recommending lightly tinted eyeglasses for persons who work all day at computer terminals.

    C) Black Light/Plant Lights - The “Black Light” is the popular term used to describe ultra-violet energy in the 3200-4000A band. This invisible energy causes some materials Inks, dyes special paints and chemicals to glow. The phenomenon is useful for various laboratory studies, for mining and mineral exploration, and for industrial inspection and production. Although relatively inefficient for lighting, black light has found considerable architectural application for decorative effects.
    Black light ( /BL) lamps are commonly used in “bug Zappers”, they produce a long wavelength UVA radiation in the range of 350 to 400 nanometers. Visible energy in the 400 to 420 nanometer range is also emitted, giving the lamps a strong blue color when operated.
    Black light Blue ( /BLB) lamps emit UVA radiation similar to BL lamps but are manufactured using a “black” glass that blocks most visible radiation. These lamps are often used decoratively, in disco lighting and theatrical production.
    Diazo Reprographic Lamps The diazo lamp emits a blue light, peaking at approximately 417 nanometers, and is used primarily in rephographic equipment that employs the diazo process.
    (G.E Spectrum, p.4-23)

    The Treated Surface: since the eye is insensitive to “black light” UV-A radiation energy (from the lamp), the impression of brightness and color depends on the placement of fluorescent chemicals for conversion. In effect, these fluorescent paints, dyes, and other coatings perform a function similar to the phosphor coating of a fluorescent lamp. Treated surfaces become “area sources”, converting invisible energy into the longer wavelengths of visible light.
    Fluorescent Efficiency: Black Light Paints, Dye, Lacquers, Water Colors:
    Red...2%, Orange...4%, Yellow....8%, Green....7%, Blue....2%
    Filters: Visible light reduces contrast and reduces the effectiveness of a black light installation. Therefore, the ambient light level should be low, and any visible energy emitted by the source should be intercepted and absorbed by a special red-purple or dark blue filter. This filter may be attached to the fixture as a cover plate, or it may be integral with the lamp (dark glass bulbs).
    Fluorens=one milliwatt of energy between 3200 and 4000 angstrom units.
    Filament Black Light Lamps: Filament lamps are inherently weak and inefficient sources of ultra-violet. In addition, large quantities of visible and infra-red energy must be intercepted, and the dark bulb (which acts as a filter) becomes very hot due to absorption. This extreme bulb heat means that the lamp can be operated only intermittently, and periodic bulb cooling is required (5 min. On, 10 min. Off.) Beam Control: Filament lamps offer inherent advantages when used in precise reflectors. But, in this case, their use is limited due to inefficiency and bulb heat. Principal lamp use is in supplementary units for close-range examination and inspection. 50 hours of life, at 250 watts puts out 470 fluorens. Advantages: no ballast or transformer required. Low cost, and light weight fixtures, and full output immediately.
    Fluorescent Black Light Lamps: special fluorescent phosphors produce the 3,200-4,000 A. Band. These lamps are highly efficient sources of black light energy. Lamps can be obtained either unfiltered, or with self filtering bulbs. Beam Control: these lamps are used in trough-type reflectors which provide good brightness distribution on elongated surfaces (walls, etc.) However, reflector control of fluorescent lamps is limited. The beam pattern will be somewhat diffused, and perhaps more significant, the projection distance is limited. Advantages: most efficient source, Little visible light to be filtered, cool operating linear source, full output immediately, 40 watt lamp can be dimmed or flashed. Dark filter bulbs reduce fluoren output to approximately 85% of unfiltered output. Approximate maintenance factor 0.50.
    Do not use these lamps for diagnostic or therapeutic purposes.
    Mercury Black Light Lamps: Mercury lamps are compact high output sources, offering advantages where accuracy of control is important. In some cases these lamps include integral filters and reflectors. Beam Control: the mercury arc provides a high output concentration of energy in a relatively small source. With proper reflector or lens design, then, the source is adaptable to give controlled beam patterns which can be projected substantial distances.
    Advantages: compact source, efficient high output, available with integral reflectors approximate maintenance factor 0.60. one G.E brand name is Gold Lamps

    Plant lights use both PL and PL/AQ phosphors were developed for use in horticultural and aquarium applications. The unique phosphor blend is designed to promote plant growth and enhance the appearance of plant and aquatic life.
    Germicidal lights are clear lamps made of a UV transmitting glass which transmits the 253.7 nanometer radiation from the mercury discharge - a wavelength effective in killing various forms of bacteria. Applications include water and air purification. Caution: these lamps emit short wavelength radiation. Be sure eyes and skin are properly protected at all times.

    Diazo = UV Radiation measured perpendicular to lamp axis at 1m. distance with a relative spectral sensitivity according to IEC. (See UV), Diazo falls between 320 and 440 nm. and includes some harmful UV-B and UV-C range. Measured as: irrad at 0hr µW/cm Square.

    UV Radiation Breakdowns:
    Ozone-producing: 180-220nm
    Bactericidal (germicidal): 220-300nm
    Erythemal (skin reddening): 280-320nm
    “Black Light”: 320-400nm
    Note: True Black light lamps are different than Black Light Blue lamps which are common for use in lighting effects, and produce a visible change to surface colors, as opposed to true black light which produces an almost in-perceivable effect on surfaces by the human eye, except with special phosphor paints and materials.
  4. ship

    ship Senior Team Emeritus Premium Member

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    “What are "uv guns"? Ultra Violet guns? Wouldn't that give the audience cancer? lol j/p!”

    Just thought it a good time for a class in UV and black Lights as I got your joke both as a weapon but many others that are not familiar with UV light guns or equipment might not be. I would go on-line to Wildfire to read more on the subject and see what dies for costumes and other products they sell as they seem to be the primary source in specializing on it. Rosco might also have some UV stuff. Wildfire (Special Effects Projector Mfr..) Also, Stagecraft recently had a discussion about it and what was recommended was to use Starch - I believe Arco brand (but you should verify) on the costumes as it seems to pick up UV well without trashing the costumes.

    For the most part, I would start with a bit of haze to the atmosphere and perhaps some chilled fog or dry ice. But it all depends upon the setting and circumstances. Also, if the lights are direct focus - Lekos and bright enough, and at a hot enough in color temperature, even if you don’t do any prosper effects, the talent will glow. I have two Century #1968 8x9 fixtures that will take a 2Kw lamp and look like squat old style cannons. They have one major purpose - it’s to make people appear as if a ghost from behind a scrim. Stick the fixtures opposing each other behind the scrim about 4' away from the place the actor will be, narrow their shutter cut to about 1' wide by 5' high, and all the ghost has to do is stick their hand out from the dark and it automatically not only glows but is disconnected from a body. Stick a head out into the light and it’s an extreme effect. While the amount of UV light coming off a incandescent lighting fixture is almost nominal, get the lights bright enough or as a metal halide or xenon source, and that percentage is enough in many instances to make things phosperescent - given distance quickly becomes a factor. You might also look into some stage lighting books such as Gelette and Pilbrow wrote that show examples of beam angles and what they look like that are focused upon at the various angles. Could gain a bit of heavenly effect just by reproducing a psychologically expected key lighting angle for them. In the afore mentioned Stagecraft postings, there was also some talk about what gel for normal instruments give the effect of UV light. My personal favorite for magical type effects or non-real settings is Lavender. Perhaps one might create an effect with bright Lekos, even boost their color temperature to around the 65K or better range, and say strip or boarder lights gelled with Lavender overhead.

    Some notes on UV fixtures. The stock fixture used is a 4' aka Home Depot T-12, 40w Black Light Blue fluorescent lamp in a fluorescent fixture. The actual output of such fixtures isn’t much in reality and won’t project much useful UV-A beyond say 10'. It also being a fluorescent isn’t much use if you want your light directional but due to it’s low intensity will do a light wash fairly well. In other words, with such fixtures unless you go to extreme with their numbers, they are not going to have a huge amount of power to them. Next problem is where do you put them? Do you rig them to a electric in taking up almost the entire pipe rigging space, do you mount them on booms and have it brighter towards the wings, or as foot lights and have an un-natural ghastly effect to it but that might be worth some experimentation given this effect and the talent stays down stage. Also, there is the cueing problems as they will dim as per any fluorescent lamp given the right ballast and dimmer - even stage lighting dimmer - especially if analog, but still will need to start as per a fluorescent which means they need to kind of flicker on at full intensity than be dimmed if not used. That is dim them to just above the point that they flicker out. Dimming also destroys the normal 20,000 hour life of the lamp making it possible you will need to replace them in a few weeks or have them go out or loose a lot of output.

    Also, it’s required to use fluorescent tube guards over them to protect against falling glass should one break. Problem is - and one that I have not found a solution to yet is that most tube guards are of a UV-Stop in nature thus it’s going to further cut back on the output. A good source for notes on such things would be Encapsulite (Special Effects Fixture Mfr./Distributer) They specialize in fluorescent sources and fixtures for entertainment, and have really cool fixtures. They might have the black light problems figured out fairly well. The fluorescent fixtures they sell would also be dimmable in addition to protected. It’s possible you could buy your tube guard lamps from them and stick them into normal fixtures. It’s also possible to get longer lengths of black light lamps from them to simplify fixtures with lengths in the MOL 1,778mm range from Europe that they import and get 100w lamps in use that should have some useful output. (Given some lead time to get the stuff from customs.) If you need me to specify a lamp for them to get contact me off line but be warned, they do like to take their time with special orders.

    So now we are left with a choice in Black Light Fluorescent lamps that most people don’t know about. Black Light Blue, and just plain Black Light. Most people just buy the home owner grade Black Light Blue lamps that give off some visable light in the blue spectrum in addition to the UV they want that way they can better see with the light. However, the vendor reps I had a meeting with recently from Osram highly recommend that if you want to get a better output in a black light fluorescent source, that you loose the blue tint and go straight black light. It’s much harder to see what your beam is doing thus the blue added in, but also much more mysterious in where it’s coming from and higher in output. Were I using a fluorescent source, and didn’t have time or budget to go with a Euro 100w version with a special fixture from Encapsulite, I would go for a more easily gotten but special order non-blue black light tube.

    All that said, Wildfire in addition to paint and stuff makes some of the best UV projectors on the market. Consider say a 8" Fresnel or 4 mounted in the first boom positions off stage and or the first electric, and having the stage covered in intense black light waves by just some 400w HMI UV sources they sell. Worth the rental on the gear that said company should be able to give details on who has their stuff, especially if your grid is already packed with scenery and lights or you want more output than fluorescents. Their fixtures work on the black light non-blue principals so it’s hard to focus them, but are very useful and recommended.

    Final step would be to add a bit of phosphor to your haze in the air and fog but such things are not on the market and would probably prove toxic.

    There is some stuff to chew on designwise.

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