Ultra Violet Lamps : Mahavir Gems
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Ultraviolet lights have many uses:

  • Mining and Prospecting at night of valuable ores such as the Tungsten mineral Scheelite, the Zinc mineral Willemite, and many secondary Uranium minerals, and also certain gems
  • Mineral Displays - A large number of fluorescent minerals react to Shortwave UV light, and a lesser amount to Longwave UV, making for outstanding displays in the dark
  • To detect forgeries and repairs from glues and paints on artwork, antiques, and collectibles such as china, glassware, pottery, and postal stamps
  • To detect special inks in evaluating Postage stamps
  • To locate pet urine on carpet and furniture, useful to both homeowners and professional cleaners
  • To view the fluorescence of scorpions and other arthropods and insects at night

Other Applications:

  • Germicidal - Short Wave UV can kill bacteria, so is used in food packing plants, koi ponds, hospitals, public restrooms, etc.
  • Automotive and industrial leak detection
  • To detect invisible criminal tagging dyes
  • To reveal dye marking of hands with invisible ink used as an admission stamp at social events
  • To trace the origin of ground and surface waters
  • For curing adhesives
  • Location and ID of fungi, ringworm, bacteria, and spermatozoa, also pollutants and arson accelerants
  • Theatrical makeup and staging
  • To reveal invisible personal property ID markers
About U.V. Lamps

UV lamps typically come in both portable models and as permanent display units, offering one or more wavelengths depending on the model.  The basic elements of a UV lamp include the power source, the ultraviolet light bulb, and the filter.

While a typical permanent display lamp runs off house current, a portable lamp is powered by batteries, some of which are rechargeable, depending on the model.  Often times, more expensive portable lamps are also configured with an AC adapter to run off of house current.

UV light bulbs are constructed of a special high silica glass, or of quartz in the finest quality.  They are rated by wattage, not unlike a bulb in your house lamp, so this can be an indication of your lamp's brightness.  However, this is not a hard and fast rule because the way in which a UV lamp is powered and designed also affects its brightness.  Shortwave bulbs appear clear when off.  Longwave bulbs, having phosphors on the inside, with or without integral filters, appear white or black (blacklight) when turned off.

Along with ultraviolet light, all UV lamps emit some visible light, too, which tends to mask any fluorescence, so special dark purple glass filters are placed over the bulb to block the visible light, while allowing as much UV light to still pass through.  Longwave filters, which have a relatively coarse surface appearance, last indefinitely.

Shortwave filters, which often have highly polished surfaces, will deteriorate over time from exposure to the very Shortwave light they are filtering, a process called solarization.  Long exposure to humidity will also damage Shortwave filters.  After about 1 to 5 months of continuous use, the filter's transmission drops to about 25%, so your mineral collection, for instance, will not fluoresce as brightly.  Thus, a Shortwave filter should be replaced when spent.

In contrast to the life of Shortwave filters, UV light bulbs last a very long time.  However, the phosphors in a Longwave bulb can deteriorate with time, so if your Longwave fluorescence appears dull, you may want to replace the bulb.  If your Shortwave fluorescence is dull, replace your filter before replacing the bulb because the bulb will withstand the effects of solarization perhaps 50 times longer than will the filter.

Keep in mind that the darker your surrounds, the easier it will be to observe the effects of fluorescence from your UV lamp.  Depending upon how bright your lamp is, you may or may not be able to use it in the daylight.   
About U.V. Light.

UV light, short for Ultraviolet Light, is a type of light energy making up one part of the electromagnetic spectrum, which spectrum includes gamma and x-rays, UV light, visible light, infrared rays, microwaves, and radio waves, listed in order of decreasing frequency and increasing wavelength.  UV light thus has a wavelength shorter than that of visible light, and can not be detected by the human eye.  While UV light itself is invisible, it causes many substances to glow or fluoresce in a variety of colors visible to the human eye.  This ability to make the invisible visible makes UV lamps valuable for mineral prospecting, criminal investigations, postal stamp evaluation, etc.

UV light is divided, at a minimum, into both Shortwave and Longwave radiation.  Shortwave UV is produced by low pressure mercury arcs, with a wavelength of 254 nanometers, while Longwave, produced by low to high pressure mercury arcs, has a wavelength of from 320 to 400 nanometers.  A nanometer is a unit of length used to define wavelengths of energies in the electromagnetic spectrum, equaling one millionth of a millimeter.

While Longwave UV, sometimes referred to as "blacklight", is safe, Shortwave UV can irritate the eyes and burn the skin, so exposure should be controlled and ideally, UV goggles should be worn to prevent eye damage from inadvertently looking at the light source.

As before stated, UV light directed at certain materials causes fluorescence, originally named after the mineral Fluorite for its blue glow under UV.  Phosphorescence is a type of fluorescence that continues even after the UV light is removed.  It can last from fractions of a second to weeks.  Of the fluorescent minerals, about 80 to 90 % of them fluoresce brighter under Shortwave than under Longwave UV.
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