Jul 06, 12
Whether you’re shooting at friends in a laser tag arena, venturing through the narrow passageways of a haunted house, or simply watching your favorite episode of CSI, black lights never cease to amaze. There’s something fun and mysterious about revealing secrets and hidden messages with that strange purple light. But how do black lights work? (Hint: It’s not magic.)
The signature glow produced by black lights requires two separate things: A source of ultraviolet light and a surface coated with UV-reactive phosphors. The source of the light is a bulb, whether incandescent, fluorescent, CFL, or LED. You can find phosphors—a loose grouping referring to special compounds and minerals—in and on all kinds of things: Highlighters, soap, rocks, glow-in-the-dark toys, and even your teeth. When ultraviolet light hits a phosphor, the phosphor glows in a phenomenon called luminescence.
Incandescent Black Lights
You may remember from our previous article on yellow bug lights that the short-wavelength spectrum of light beyond visible light is ultraviolet light. All light sources produce UV in varying quantities. For example, the simplest form of black light, an incandescent black light, produces very little ultraviolet light but uses a special filtering glass called Wood’s Glass to block most visible light produced by the bulb filament, thus enhancing the effect of the UV spectrum. However, the relatively small amount of UV light incandescent bulbs produce makes incandescent black lights the least impressive of black lights.
Fluorescent Black Lights: BL vs. BLB
Fluorescent light sources naturally emit much more of the ultraviolet light spectrum, making the technology ideal for use in black lights. Fluorescent black lights fall into two different categories, black light (BL) and black light blue (BLB). Fluorescent black lights use special phosphor coatings on the inside of the bulb to filter out visible light and enhance the emission of ultraviolet light. In both BL and BLB technologies, this ultraviolet light causes external phosphors in its surroundings to glow, just like an incandescent black light does. However, because fluorescent technology produces much more of the UV spectrum, fluorescent black lights are more effective than incandescent black lights.
While both a fluorescent black light and a black light blue use UV light and phosphor coatings to create luminescence, the difference between them is how much invisible ultraviolet light they emit in relation to visible white light. A fluorescent black light, which appears similar to any ordinary white fluorescent lamp, emits a relatively large amount of white light mixed with ultraviolet light. The light from a fluorescent black light looks similar to what we are used to from ordinary fluorescent sources, yet still causes limited luminescence of external phosphors.
Black light blue fluorescents are much more commonplace. Like other fluorescent black lights, they use a special phosphor coating to filter white light; however, for more complete blocking of white light, black light blue bulbs also are made of a purple-colored filtering glass. This combination allows them to emit a greater amount of ultraviolet light than white light. The result is the familiar purple-colored light and a very pronounced luminescence of phosphors in black light reactive objects.
Other Black Light Technologies
Of course, fluorescent black light technology lends itself equally well to compact fluorescent black lights. Though compact, CFL black lights work according to the same principles of black light or black light blue fluorescent lighting. LED black lights are less common, though they are starting to emerge, especially in stage and nightclub lighting. Other niche applications include HID lighting, especially mercury vapor, and “bug zapper” lights like the Paraclipse Mosquito Eliminator.
We hope we haven’t completely destroyed the mystique of black lights for you. But if we have, be sure to let us know in the comments, or drop us a line on Facebook, Google+, or Twitter page.
Jun 29, 12
It’s a long accepted fact that production of the hormone responsible for sleepiness, melatonin, can be suppressed by light. The pineal gland uses the presence of light to determine when to release and suppress the hormone, setting our “internal clock” to a cycle of wakefulness and sleep, also known as a circadian rhythm. Not surprisingly, the large amount of artificial light we encounter in the modern world can have a negative effect on this cycle by suppressing melatonin production even at night. However, recent studies suggest that not just the amount of light, but also the color of the light we encounter may affect our sleep cycles.
A 2005 study conducted by researchers at Kyushu University in Japan suggests that exposure to high color temperature light immediately preceding bedtime reduces the length of stage 4 sleep. In the study, the researchers exposed different subjects to 3000K, 5000K, and 6700K light sources for 6 hours before going to sleep. Researchers monitored the subjects’ sleep patterns and came to this conclusion:
Given that the S4-sleep period is important for sleep quality, our findings suggest that light sources of higher color temperatures may reduce sleep quality compared with those of lower color temperatures.
Other studies by the University of Basel in Switzerland and the University of Connecticut found similar results.
Though these findings are not yet accepted scientific fact, it’s worth noting that manufacturers have already started to create products with these ideas in mind. Philips, for example, produces an entire line of “Wake-Up Lights” that use increasing light intensity and color temperature to wake you from sleep, a method that is marketed as a more natural alternative to alarm clocks. The computer program and smartphone app f.lux reduces the color temperature of screens for less obtrusive nighttime reading. On the flip side, companies have long used “full spectrum” office lighting to increase alertness and productivity, assuming that if high color temperature lighting discourages sleep, it must also encourage wakefulness.
While the scientific community works this all out, what can you do now to improve your sleep? Start with what we do know: Bright light of any color temperature suppresses the production of melatonin, so limit the use of artificial light in the hours preceding sleep. This is easy to do with dimmers, 3-way bulbs, and even low wattage bulbs. Second, conduct your own study: If you currently use high color temperature bulbs and have difficulty sleeping, switch them out for soft white or warm white bulbs and see if you notice a difference.
If you try these ideas out, we’re curious about the results. Does color temperature have any effect on your sleep? Let us know in the comments, or drop us a line on Facebook, Twitter, or Google+.
May 11, 12
Every light source has a distinct character, from the warm, dim glow of a candle to the blue, bright beam of a street light. Brightness, measured in lumens, is one part of that character; the other part is color temperature. Measured in degrees Kelvin, color temperature is not the ambient hot/cold temperature of our surroundings. In fact, the Kelvin scale goes backwards: The higher the color temperature, the cooler light gets, and the lower the color temperature, the warmer light gets.
Warm Color Temperatures (2000K to 3500K)
Lighted Makeup Mirror
Most homes look best in warm-toned light. This is for several reasons, but the first one is a home’s color scheme. People tend to decorate homes in warm earth tones—reds, oranges, and yellows—which warm light enhances. In addition, people tend to look better in warm light. If your grandmother had a lighting makeup mirror with adjustments based on “office,” “home,” and “evening” lighting, you may remember that you looked a lot better in “home” and “evening” modes than “office” mode. That’s because (you guessed it!) those modes had lower color temperatures than “office” mode.
Cool Color Temperatures (4000K to 4500K)
While warm color temperatures are the residential standard, some people prefer higher or “cooler” color temperatures. Because of their neutral tone, it’s common to see color temperatures of 4000K or higher used as task lighting in offices. Moreover, people often perceive higher color temperatures to be brighter than warm temperatures, while others feel cooler light looks “cleaner.” Finally, higher color temperatures can enhance homes with cooler color schemes, especially those with a lot of blues and whites.
Full Spectrum Color Temperatures (5000K to 6500K)
Less common are very high color temperatures, often referred to as “full spectrum” or “daylight.” Color temperatures of 5000K to 6500K approximate the color of light outdoors on a bright, sunny day. The cast of the light can be a very pronounced blue and can seem harsh to some people. It’s unlikely to see color temperatures of this range in homes, though there is a trend of installing “full spectrum” bulbs in offices as they are sometimes associated with higher productivity.
Making a Decision
There’s nothing that can sour your opinion of CFL or LED lighting like buying a 4000K or 5000K bulb when you meant to buy a 2700K bulb, or vice-versa. When you buy a new, energy efficient bulb, keep your application and color scheme in mind and make sure to buy the bulb with a color temperature to match.
So do you prefer warm or cool color temperatures in your home? Have you ever mistakenly bought a bulb of the wrong color temperature? Share your thoughts and experiences in the comments section below or contact us on Facebook, Twitter, or Google+.
Feb 21, 11
Full spectrum lighting is an industry term for lighting which offers wavelengths from all parts of the light spectrum. Light is a form of electromagnetic radiation visible to the human eye. There is a range of the electromagnetic radiation wavelengths. The visible light lies between the infrared and ultraviolet frequencies in this range. Most household and commercial lighting only uses part of this range of visible light. This is due to the technology used in the bulb. The light coming from a light bulb can affect many things in both the plant and animal worlds.