Monday, October 22, 2007


Fluorescence - Wikipedia, the free encyclopedia


From Wikipedia, the free encyclopedia

Fluorescent minerals
Fluorescent minerals

Fluorescence is a luminescence that is mostly found as an optical phenomenon in cold bodies, in which the molecular absorption of a photon triggers the emission of another photon with a longer wavelength. The energy difference between the absorbed and emitted photons ends up as molecular vibrations or heat. Usually the absorbed photon is in the ultraviolet range, and the emitted light is in the visible range, but this depends on the absorbance curve and Stokes shift of the particular fluorophore. Fluorescence is named after the mineral fluorite, composed of calcium fluoride, which often exhibits this phenomenon.

I'm not going to lie, the rest of this article is definitely to technically involved for my comprehension. Unfortunately I am not a physicist. But holy shit, those minerals look amazing! Like I said, I'm a sucker for bright colours.

Continuing on....

Blacklight paint

From Wikipedia, the free encyclopedia

Blacklight Ink or blacklight-reactive Ink is ink that glows under a blacklight (a source of light whose wavelengths are primarily in the ultraviolet range). The paint may or may not be colorful under ordinary light. It is also known as Fluorescent.

Such paints and inks are commonly used in the production of blacklight posters. Under daylight, the ultraviolet light ordinarily present makes the colors especially vivid. Under blacklight (with little or no visible light present), the effect produced can be psychedelic. The inks are normally highly sensitive to direct sunlight and other powerful light sources. The fluorescent dyes cause a chemical reaction when exposed to high intensity light sources (HILS) and the visual result is a fading in the colors of the inks. On paper, you would most likely observe a significant visible change in the color saturation within 45 minutes to one hour of exposure to the HILS. To date, there is no absolute method to prevent this phenomena. Certain laminations, lacquer coatings, and glass or plastic protective sheets can effectively slow the fading characteristics of the dyes.

Other common usage of the blacklight inks is in security features of money notes, various certificates printed on paper, meal coupons, tickets and similar things that represent a value (monetary or otherwise). The blacklight printed figures used for this purpose are usually invisible under normal lighting, even when they are exposed to direct sunlight (which contains ultraviolet light) but they show up glowing when exposed to blacklight source. This defeats simple and inexpensive attempts to counterfeit them by scanning the original using a high resolution scanner and printing them using an inexpensive high resolution printer (most if not all inexpensive printers don't allow using blacklight inks for printing[citation needed]) and no special equipment is needed to verify the presence and correctness of this feature (an inexpensive blacklight source being handy is all that is needed). Some coupons and tickets use colorful blacklight inks.

Blacklight paints are sometimes used in the scenery of amusement park dark rides. A blacklight illuminates the vivid colors of the scenery, while the vehicle and other passengers remain dimly lit or barely visible. This can enhance the effect of being in a fantasy world.

Blacklight paints may be fluorescent or, more rarely, phosphorescent, containing a phosphor that continues to glow for a time after the blacklight has been removed.

Glowy, fun psychedelic stuff... I definitely need to get myself some blacklights for my room, but sometimes they're hard to find. I bought a couple once, and unbeknownst to me, they were just purple lights. I had no way of knowing they were fake at the time.

Black light

From Wikipedia, the free encyclopedia

Spectrum of a fluorescent black light source. FWHM spectral bandwidth of the 370nm peak is about 20nm.

Black light (also Wood's light) is the common name for a lamp emitting electromagnetic radiation that is almost exclusively in the soft near ultraviolet range, and very little visible light. In many areas this type of lighting is more commonly referred to as simply "UV light".


Fluorescent black lights are typically made in the same fashion as normal fluorescent lights except that only one phosphor is used and the normally clear glass envelope of the bulb may be replaced by a deep-bluish-purple glass called Wood's glass, a nickel-oxidedoped glass, which blocks almost all visible light above 400 nanometers. The color of such lamps is often referred to in the trade as blacklite blue.

The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate (SrB4O7F:Eu2+) or europium-doped strontium borate (SrB4O7:Eu2+) while the phosphor used to produce a peak around 350 to 353 nanometers is lead-doped barium silicate (BaSi2O5:Pb+). "Blacklite blue" lamps peak at 365 nm.

A black light may also be formed by simply using Wood's glass instead of clear glass as the envelope for a common incandescent bulb. This was the method used to create the very first black light sources. Though it remains a cheaper alternative to the fluorescent method, it is exceptionally inefficient at producing UV light (a mere few lumens per watt) owing to the black body nature of the incandescent light source. Incandescent UV bulbs, due to their inefficiency, may also become dangerously hot during use. More rarely still, high power (hundreds of watts) mercury vapor black lights can be found which use a UV emitting phosphor and an envelope of Wood's glass. These lamps are used mainly for theatrical and concert displays and also become very hot during normal use.

Some UV fluorescent bulbs specifically designed to attract insects for use in bug zappers use the same near-UV emitting phosphor as normal blacklights, but use plain glass instead of the more expensive Wood's glass. Plain glass blocks less of the visible mercury emission spectrum, making them appear light blue to the naked eye. These bulbs are sometimes referred to as "blacklite" or "blacklight blue".

Ultraviolet light can be also generated by some light-emitting diodes.

So the fake black light I got was just an incandescent light with a purple tinge to it. I need to find a science store around here, and ask for a Wood's Light.

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