Fluorescent light

A "normal light bulb" is also known as an incandescent light bulb. These bulbs have a very thin tungsten filament that is housed inside a glass sphere. They typically come in sizes like "60 watt," "75 watt," "100 watt" and so on.

The basic idea behind these bulbs is simple. Electricity runs through the filament. Because the filament is so thin, it offers a good bit of resistance to the electricity, and this resistance turns electrical energy into heat. The heat is enough to make the filament white hot, and the "white" part is light. The filament glows because of the heat -- it incandesces.

The problem with incandescent light bulbs is that the heat wastes a lot of electricity. Heat is not light, and the purpose of the light bulb is light, so all of the energy spent creating heat is a waste. Incandescent bulbs are therefore very inefficient. They produce perhaps 15 lumens per watt of input power.

A fluorescent bulb uses a completely different method to produce light. There are electrodes at both ends of a fluorescent tube, and a gas containing argon and mercury vapor is inside the tube. A stream of electrons flows through the gas from one electrode to the other (in a manner similar to the stream of electrons in a cathode ray tube). These electrons bump into the mercury atoms and excite them. As the mercury atoms move from the excited state back to the unexcited state, they give off ultraviolet photons. These photons hit the phosphor coating the inside of the fluorescent tube, and this phosphor creates visible light. It sounds complicated, so lets go through it again in slow motion:

There is a stream of electrons flowing between the electrodes at both ends of the fluorescent bulb. The electrons interact with mercury vapor atoms floating inside the bulb.

The mercury atoms become excited, and when they return to an unexcited state they release photons of light in the ultraviolet region of the spectrum. These ultraviolet photons collide with the phosphor coating the inside of the bulb, and the phosphor creates visible light. The phosphor fluoresces to produce light.

A fluorescent bulb produces less heat, so it is much more efficient. A fluorescent bulb can produce between 50 and 100 lumens per watt. This makes fluorescent bulbs four to six times more efficient than incandescent bulbs. That's why you can buy a 15-watt fluorescent bulb that produces the same amount of light as a 60-watt incandescent bulb.

The Districts Fluorescent Bulb Recycling Program has expanded once again to include four new locations: Umber's Do It Best on Maplecrest and Lower Huntington Rd, Grabill Hardware and Connelly's Do It Best on Illinois Rd. Allen County residents can recycle their burned out fluorescent bulbs free of charge at any of the 8 locations around town.

Fluorescent bulbs use 75% less energy and last 10 times longer, but they should be recycled as they do contain a pen tip amount of mercury.

Our industry has enjoyed several leaps in fluorescent bulb technology; yielding more power and greater efficiency with each generation. From VHO to Power Compacts, the calling card of each new leading technology has been a jump in lumens per watt. Enter High Output T5 fluorescents. A modest increase in efficiency over PC fluorescents is not the whole story here. The diminutive diameter of the T5 bulbs places little in the way of light rebounding from the reflector and offers a new benchmark in terms of the light produced making it into the aquarium for a significant and apparent improvement

The laser process creates a unique array of nano- and micro-scale structures on the surface of a regular tungsten filament�the tiny wire inside a light bulb�and theses structures make the tungsten become far more effective at radiating light

We've been experimenting with the way ultra-fast lasers change metals, and we wondered what would happen if we trained the laser on a filament," says Chunlei Guo, associate professor of optics at the University of Rochester. "We fired the laser beam right through the glass of the bulb and altered a small area on the filament. When we lit the bulb, we could actually see this one patch was clearly brighter than the rest of the filament, but there was no change in the bulb's energy usage.

The key to creating the super-filament is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed, consider that a femtosecond is to a second what a second is to about 32 million years. During its brief burst, Guo's laser unleashes as much power as the entire grid of North America onto a spot the size of a needle point. That intense blast forces the surface of the metal to form nanostructures and microstructures that dramatically alter how efficiently can radiate from the filament.

In 2006, Guo and his assistant, Anatoliy Vorobeyv, used a similar laser process to turn any metal pitch black. The surface structures created on the metal were incredibly effective at capturing incoming radiation, such as light.

"There is a very interesting 'take more, give more' law in nature governing the amount of light going in and coming out of a material," says Guo. Since the black metal was extremely good at absorbing light, he and Vorobyev set out to study the reverse process�that the blackened filament would radiate light more effectively as well. "We knew it should work in theory," says Guo, "but we were still surprised when we turned up the power on this bulb and saw just how much brighter the processed spot was."

In addition to increasing the brightness of a bulb, Guo's process can be used to tune the color of the light as well. In 2008, his team used a similar process to change the color of nearly any metal to blue, golden, and gray, in addition to the black he'd already accomplished. Guo and Vorobeyv used that knowledge of how to control the size and shape of the nanostructures�and thus what colors of light those structures absorb and radiate�to change the amount of each wavelength of light the tungsten filament radiates. Though Guo cannot yet make a simple bulb shine pure blue, for instance, he can change the overall radiated spectrum so that the tungsten, which normally radiates a yellowish light, could radiate a more purely white light.

Guo's team has even been able to make a filament radiate partially polarized light, which until now has been impossible to do without special filters that reduce the bulb's efficiency. By creating nanostructures in tight, parallel rows, some light that emits from the filament becomes polarized.

The team is now working to discover what other aspects of a common light bulb they might be able to control. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it to augment regular light bulbs should be relatively simple. Guo is also announcing this month in Applied Physics Letters a technique using a similar femtosecond laser process to make a piece of metal automatically move liquid around its surface, even lifting a liquid up against gravity