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Laser projector colors and types

These generally use three lasers that are red, green and blue. They are combined into a single beam.  If all lasers are at full power, the combined beam is white. By controlling how much red, green or blue is added, the beam becomes different colors.
 

16.7 million colors
Most full-color projectors use analog modulation of the red, green and blue lasers. There are 256 levels of each color, giving 256 x 256 x 256 or 16.7 million different shades. Analog modulation also allows gradual dimming of the colors, so the graphics can fade in or out.
 

Seven different colors
A few full-color projectors use only TTL on-off modulation of the red, green and blue lasers. There are two levels of each color, on or off, giving seven colors: red, yellow, green, cyan, blue, magenta and white. It is not possible to have in-between shades, or to have gradual dimming. A color is either on or off.

Red-green laser projectors

These have two laser colors, red and green. If the red and green are mixed in varying amounts, you can get orange, yellow, and yellow-green shades.
 

Single-color laser projectors

Graphics laser projectors

Graphics projectors use "scanners" to move the beam fast enough to make detailed images projected on a screen or wall. Graphics projectors can draw outline images of pictures, logos, text and other complex shapes.

Graphics projectors can also make patterns. These can be simple geometric shapes like circles, squares and stars. They can also be complex 3D shapes like the ball at right, as well as psychedelic, hypnotic abstract images from classic planetarium-type shows.

If the projector is turned around, and aimed towards an audience, a graphic projectors can work as a  beam projector. They can create both simple (traditional) and complex beam designs, as shown at right.

Scanners are rated by how fast they can show the ILDA test pattern, developed by the International Laser Display Association.

• As of 2005, ILDA 60K (60,000 points per second) is the fastest possible
• Scanners from about ILDA 30K to 60K are considered professional quality
• Scanners from ILDA 12K to about 24K are considered acceptable quality for graphics
• Scanners slower than 12K this are best suited for making patterns (see below)

Usually the images made by a graphics laser projector are outline (vector) drawings. However, it is possible to do low-resolution TV-like raster graphics as well.

Airplane, 3D ball and raster girl photos
courtesy Pangolin Laser Systems Inc.

Pattern laser projectors

Pattern projectors can make simple shapes. Projecting these through theatrical fog makes interesting beam designs.

Some lower-cost projectors use slow scanners (below ILDA 12K) or stepper motors to move the beam. These "pattern" projectors can show simple geometric shapes like circles, squares and stars on a screen or a wall. They are not suited for showing logos, text, detailed shapes or other complex graphics.

If the projector is turned around, and aimed towards an audience, it becomes a beam projector that can create interesting beam designs such as cones or planes of light. The pattern projector also can aim the laser to many different locations, creating "Star Wars"-like beam shows, as shown at right.
     Since beam effects do not require high-quality graphics, pattern projectors are fine for making professional-quality laser beam shows.

Beam laser projectors

This club installation uses bounce mirrors to fill the space with laser light.

Shooting laser beams at or over an audience is a guaranteed crowd-pleaser. There are two main types of beam projectors:

• Beam tables use a small number of mirrors (typically between 6 and 24) to re-direct the laser beam. Each beam position can aim at a target such as a bounce mirror, or can create an effect such as a spray of smaller laser beams. A beam table can aim the beam very accurately and repeatably to bounce mirrors, but it has a limited number of positions.
   
• Beam projectors use two scanners or stepper motors which aim tiny mirrors under computer control. Together, the two scanners can aim the beam anywhere in front of the projector.
       The advantage is that there are an infinite number of positions that can be hit, and shapes that can be made. However, beam positioning may not be as repeatable, which is important in a club when you are hitting many bounce mirrors.

The best of both worlds is a beam table where scanners are located at one of the positions. When this position is selected, the beam can then be sent anywhere in the area in front of the projector.

Note that any Graphics or Pattern projector can be used as a beam projector. Just turn the projector around to face the audience, and add theatrical fog to the air.