Laser Dazzle

Laser Dazzle

Maia Weinstock

Ready for the “wave” of the future? Get ready to rock with largest!

It’s Saturday night, and you’re crammed in a concert arena with thousands of screaming fans, waiting for 98 [degrees] to hit the stage. Suddenly, the hall goes pitch-black except for four beams of green light that pinpoint each emerging band member. The crowd screeches as the arena throbs with pounding music and a dazzling explosion of multicolored lights. Awesome squiggles of light are literally dancing with 98 [degrees]! It’s hard to tell which is more mesmerizing–the music or the light show. But one thing’s for sure: the light effects aren’t magic, they’re science!

The spectacle is created by lasers (LAY-zers), machines that shine concentrated beams of colored light. Lasers are used everywhere today: Doctors use lasers to perform eye surgery, relieve back pain, and fill teeth; engineers use lasers to weld machine parts; your supermarket clerk uses lasers to scan product prices at the checkout counter. Now, the entertainment industry has harnessed the power of lasers as never before, using light to scan compact discs, rev up planetarium shows and concerts with eye-boggling images, and enthrall audiences with movie special effects.

LASER MAGIC

Why is laser light today’s lighting tool of choice in entertainment? “No other medium can leap off the stage and grasp the audience!” says L. Michael Roberts, head laserist at Laser F/X in Burlington, Canada. As a laserist, Roberts designs and stages laser light shows for concerts, dance clubs, and movies.

You may have seen lasers at work in a planetarium sound-and-light show. Planetarium “concerts” use laser beams to devise light images that move to the beat of preprogrammed music. “To make a particular design, you deflect (bounce) laser light off of moving mirrors attached to small motors,” explains Edgar Sida, a laserist at Laser Images in Van Nuys, California. “The motors hooked up to computers move to the beat of the music,” he says. By connecting the planetarium’s audio source to the lasers, images projected onto the planetarium dome beat in sync with the rhythm of the music. Result: a stellar light display that grooves with your favorite hits.

NEW WAVE

Invented in 1960, laser is short for “light amplification by stimulated emission of radiation”–but most people just use the acronym (word formed from the initials of a multiword name). Lasers produce brilliant special effects because they shine a very particular kind of light: laser light.

Laser light differs from white light, the light from a light bulb or from the sun. White light is made up of all colors of the rainbow, a property you can discover yourself by shining white light into a prism, a triangular crystal that refracts (bends) white light rays into a spectrum, or range of all colors (see diagram below). Laser light, in contrast, consists of only one color at a time.

All light is made up of photons particles that travel through air and space in waves. And each color of the rainbow has a different wavelength, the distance between two corresponding points on consecutive waves. Photons of white light scatter, or spread out, in all directions. But laser light waves travel in the same direction and consist of only one wavelength. This creates a straight, single-colored beam of light.

Lasers used in concerts are typically filled with a gas such as argon or krypton, and are surrounded by a power “coil” that acts as an energy source. Electricity from the coil “excites” gas atoms inside the laser tube by giving them a burst of energy. But the gas atoms don’t stay excited for long; eventually, they return to their original ground energy state, releasing the extra energy in the form of a photon of light. Once released, light photons bounce back and forth between the laser tube’s two mirrors (see diagram, upper left). When the excited gas gives off enough energy, photons shoot out of the tube as a colored laser beam.

LASERS EVERYWHERE

Because of the unique properties of laser light, laserists create effects impossible to make with conventional light. In fact, many people see laser presentations as an art form. “Artistically, I can create multicolored, three-dimensional, dynamic (changing) sculptures in the air,” says Roberts.

Last October, Texans got an eyeful of amazing laser art when the Houston skyline blazed with lasers shooting in all directions from city rooftops. Powerful lasers were used to create incredibly strong light beams, so the show was visible to anyone standing within several kilometers of Houston.

If you live near a city, you can also find lasers pumping with the music in dance clubs and “raves,” huge dance parties. Laserists such as Roberts manually change laser colors and designs to match a club’s changing mood. Roberts does this by inputting effects and color schemes into a computer connected to the club’s lasers.

You can watch lasers in action at movie theaters as well. Lasers add special lighting effects to sci-fi flicks like Batman and Robin and Entrapment, as well as cartoon-inspired movies like Inspector Gadget and the upcoming Rocky and Bullwinkle. “Laser light gives movies weird, wild, and interactive light on the set,” says Kevin McCarthy at Laser Media in Los Angeles, California.

With lasers taking a starring role in all areas of entertainment, it’s no wonder that they’re the “wave” of the future!

The Visible Spectrum at Work

Light energy travels in waves. Each color of visible light has a different wavelength, or distance between the same point on consecutive waves. Red has the longest wavelength and violet has the shortest.

HANDS-ON SCIENCE

Loopy LIGHT

How do laser light shows produce elaborate patterns?

Try this activity to find out!

YOU NEED:

* flashlight with a narrow beam

* dark room

* colored cellophane (thin plastic)

TO DO:

Shine flashlight onto an empty wall or ceiling. What do you see? Why can’t you see the entire beam of light from the flashlight to the wall? How might you prove that light waves are traveling from the flashlight to the wall?

Make circles or “figure eight” loops on a wall by swinging the flashlight very quickly. Like lasers, flashlights shine one straight beam of light at a time. Why, then, do you see complete circles and other patterns? (Hint:Think of what happens when you look into a bright light for a few seconds.)

DON’T STOP NOW!

Laser light shows typically use many different colored lights. Using colored cellophane, cover one or more flashlights and swirl the light around. What happens when you put two pieces of cellophane on one flashlight?

COPYRIGHT 1999 Scholastic, Inc.

COPYRIGHT 2000 Gale Group