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RGB Whitelight Laser Light Show

Introduction:
Since I had a small air cooled argon and a HeNe laser laying around, I figured I might as well put them to good use as a modulated RGB laser source for my basic lightshow projector. With the help of a local surplus outlet I found a couple modulators and a trichro, and with that I had all the necessary components.

Description:
The source consists of a Melles Griot 05-LHR-911 5mW Helium Neon laser for red colors and a JDS Uniphase Cyonics 2201-40MLA 40mW multi-line Argon laser for green and blue. Each color is modulated separately and then recombined using a series of dichroic optics (the aluminum box in the center).

At the output of the system I have a modulated laser source that I can feed into my basic lightshow projector for scanning. Show below is the complete system, dangling precariously off the bench:

Alignment of all the optics is important to get a single clean "whitelight" beam on the output. My system consists of about 50% professional mounts and 50% things I cobbed together, however I found that it was very useful to have at least one laser on a professional mount. At this point my system could still use some more alignment, as revealed in the pictures below, but it is good enough for now. The two squarish lines in the following pictures switch between red, green, blue, purple, aqua, yellow, and white as the line progresses. The other two images are part of a pre-made laser show from Jurmo.de.

Software:
For the moment I am using the Popelscan software - it's free, supports 7-colors, and has some pre-made shows available. I am using the rgb blanking circuit from PhotonLexicon.com. The circuit is assembled in an old laser pointer case, and connects to the same parallel port cable as the X/Y DAC. Make sure when you use this circuit, enable the "Switch PCB" option in Popelscan!

Modulators:
The modulation of each laser is performed using surplus Xerox Acousto-Optic Modulators (AOMs) part number 62S87279 and the matching RF driver number 101P87160. These are fine little modulators, and from what I can tell they operate equally well across the visible spectrum. In order to make them work you have to apply a -5V level to the "-5.2V" pin, and -0.65V DC bias to the "Video In" port (thanks to David Zurcher and the alt.lasers newsgroup for that information!). This bias can easily be accomplished with a resistive voltage divider between the -5V and GND pins.

The Xerox modulator (Left), The inside of the modulator (Center), The driver showing bias potentiometer (Right).
The modulation signal is applied to the "4-30VDC" pin in the form of a 4-30V analog or +30V digital signal. Because I am using the Popelscan software all I need is TTL blanking so I threw together a simple TTL transistor buffer/driver circuit.