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Show Basics: Laser Graphics

Small Beam of Light
Leads to Dazzling Images
By Ivan Dryer, Laser Images

Animated Neon! That's an approximate description of laser scanning: the richly colored line-drawing quality of a neon sign set in motion with equal contrast and even greater color saturation. It's a medium that makes any message special. Laser scanners can project names, logos and animated imagery onto almost any surface-including the side of a mountain, the curved dome of a planetarium, even a sheet of pulsating water. Just about everybody would like to see their name in lights-especially laser lights. What's involved?

A laser produces a tiny linear beam of intense light that appears as a small dot when it strikes a surface. To make it move you have to "scan" it by wiggling one or more mirrored surfaces. Once the dot of light moves fast enough, a phenomenon called persistence of vision causes your eye to perceive the movements of the dot as solid lines of light.

In the Beginning
Early laser hobbyists mounted mirrors on speaker cones to create wildly gyrating ribbons of laser light that literally danced to the music.
Then, small mirrors mounted on rotating shafts (galvanometers) were used to create repeatable excursions (back and-forth motions) that scan a "line" of light. The line was called an "x axis." And by bouncing that x-axis line off another galvanometer mirror moving in a different direction (the y-axis), circles and more complex shapes called Lissajous figures could be generated. And thus was x-y scanning born.

Over the years, since the first galvo scanning was done in the 1960's, galvo's have gotten faster, wider in scan angle, and have added position feedback to cause them to stop very nearly at the same point at the end of each excursion. This made x-y scanning far more accurate. And it allowed line drawings of simple representational images such as faces and words to be made.

The introduction of a third scanner, or a rapidly-pulsed crystal called an acousto-optic modulator, allowed images to be "blanked" so that unwanted connecting lines could be omitted and so that dimming and brightening of the image could impart a sense of depth, or 3D. This vastly improved the ability to create more complex images with a single x-y scan set, including wireframe 3D renderings very much like CAD designs.

Full-Color Scanning
Most recently, the polychromatic acousto-optic modulator (PCAOM) was introduced to make full-color RGB (for red/green/blue) scanning simple and effective. Now, it's possible to assign different colors to different parts of the image with full control of the color assignment during animation.

So how is laser animation or a laser graphic (a word, corporate logo, or other static image) made? It's done by connecting the dots in much the same way children's coloring books do. The points are entered into a computer operating with special laser graphic software. The primary limitation on the complexity of the scanned image mirrors is the low kilohertz range in which most of today's x-y scanners operate .

The speed and accuracy of the scanner--and the software driving it--determine how many points can be accurately hit without overshooting, or "ringing." The process of entering and editing the points is called digitizing, and a good digitizer learns the scanner characteristics well enough to know how to place the minimum number of points in just the right places to create the most complex graphic frames possible.

If the frame is part of an animation sequence-such as a player throwing a ball--a sequencing program is employed to put each frame in its proper place in the action sequence.

But what if the x-y scanners simply can't move fast and accurately enough to generate the image you must have? Complexity can be readily, if not inexpensively, increased by adding one or more additional channels--in other words, more x-y scanners with blanking systems such as PCAOM's. These scanner sets are registered together, and the labor of creating the complex graphics or animation is divided between them.

It's also possible to project three-dimensional scanned images. The most common technique for achieving this requires viewers to wear polarized eyewear and a laser projector that can simultaneously project two versions of the same image polarized along different axes. Specially polarized glasses separate the images so each eye sees a different view of the same image-the result can be stunning stereoscopic laser imagery.

Planning Your Show
When you've decided you want to see your name in laser light, how do you decide what you need as a light source? To answer those questions, even more have to be asked, such as: What color or colors are required? Can it be monochrome? What is the audience size? Who will create and operate the scanned display? Are the necessary utilities (power, water) at the site? Does a screen have to be brought in and rigged?

The answers to these questions are often best left to professional laser companies that specialize in creating and displaying scanned graphics. Given the size of the audience and the effects wanted, it's a fairly straightforward process to determine the laser power required and how much scanning hardware will be needed to create the desired imagery. The scanned images can be supplemented with aerial laser beams and pyrotechnic effects, all synchronized to the same musical soundtrack.

Cost Factors
So what will it cost? That, of course, has a lot to do with how big your image is and how complex and colorful the animation must be. The laser power, color requirements (a red-only Helium-Neon laser is relatively inexpensive) and image complexity/duration are the keys to cost. A static logo from an EPROM chip, projected on a small screen indoors can be quite low in cost. The next step up would be low- or medium-power full-color projector suitable for indoor and small-scale outdoor installations.

At the high-end of the scale, say for an outdoor audience of 1,000 people, you may require a high-powered, water-cooled laser system that can cost several thousand US dollars to rent for an evening (of course, additional nights are substantially less expensive).

Although a custom-designed laser graphics sequence is far less costly to produce than computer-designed video animation, it can still cost several thousand dollars per minute for original, top-quality laser animation work. Costs can be kept down by using stock animation images and by reducing the complexity of the original artwork.

When showtime comes around, you turn on the laser, press the play button on the digital tape deck that stores the music and image data for your show, and mesmerize a big crowd that gives you a standing ovation. Best of all, your client or product has been well served by a tiny beam of dazzling laser light that creates images that make film, video and slides look pale in comparison. The best laser graphics are big, bright, colorful and sophisticated. When you need to make a statement and get attention, nothing else will match a laser.

Ivan Dryer, president of Laser Images, is a past president of ILDA and recipient of the association's Career Achievement Award.

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Images from top:
Laser Images, Inc.,
Laserland GmbH,
Laser Systems Europe