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Low Budget Laser Graphics System Many experimenters would like to build a
graphics system to use with their laser. Most graphics systems are expensive
professional systems costing thousands of dollars and offering a host of
features and effects. Here we describe the lowest cost possible X-Y graphics
system you can build. We are assuming that you are friendly with your
soldering iron and have the tools and experience to build the system.
Projector The limiting factor in graphics
projection is the scanning system which forms the heart of the projector.
You need scanners that are fast enough and accurate enough to follow the
complex graphic signal. Most professional projectors use closed loop galvos
with position detection and high quality drive amps costing $2,400 US$ and
up.
The scanners have to be held in a rigid relationship at right angles to one another and with the mirrors as close together as possible in a scan stage or scan head. This can be as simple as two small pieces of 5 mm (3/8") aluminium plate bolted together to form a right angle, and that have holes drilled to accommodate the scanners. The more professional approach is to use a scan head - a small box that holds the scanners and mounts on a spigot. This allows the scan pair to be rotated about the incoming beam so that the image can be positioned without tilting the laser projector.
Laser Naturally you will need a laser. The
typical diode laser is small enough that it could be mounted directly to the
scan head giving a projection system that occupies a very small space. With
a HeNe of small argon laser you will need a base-plate to mount the laser
and the scan head. A piece of 5 mm (3/8") aluminium will work fine. If
you are using a scan head, then it is easier to adapt the projector to
different lasers than with a right angle stage assembly.
Graphics Software You can obtain free X-Y graphics software
by downloading the original Pangolin LSD1000 software. This is Pangolin's
original laser graphics software from several years ago and once sold for
$750 US$ per copy. It is now available free as no updates or technical
support are provided (other then the documentation that comes with the
software). The software can do animations, text and beam effects and
features an array of tools to make image creation and editing relatively
simple. To download the software, visit http://www.pangolin.com/products/pricelist-lsd1000.htm
Computer System The Pangolin software runs on Amiga computers only
so you will have to obtain one and modify it to make the outputs suitable
for use with the scanning system. Only the A500, A600, A600HD and A2000 are
suitable for modifications. Some of these Amiga computers use SMT (Surface
Mount Technology) which is difficult to modify the A500 and A2000 are the
easiest to modify. Used A500's sell for between $300 and $600 $US in
computer papers or through Amiga user groups, while a used A2000 will cost
between $500 and $800 US$ depending on the accessories. The A500's typically
do not have hard drives although an outboard plug-in hard drive was
manufactured by Commodore and others and may still be available. The
software runs fine from floppy disk but is a lot slower loading frames than
using a hard drive.
Modifications The computer's sound output section needs to be modified to pass DC and to create a bi-polar output for the scanners. The modification is simple if you are familiar with op-amps as it consists of a 1458 dual op amp, a small DC power supply and a few resistors. Note: While this circuit is labeled A500 bi-polar mod, it will work with any model Amiga except the original A1000 model. Once the board is installed you will have to adjust the trim pots to centre the laser beam when no graphics signal is present and then adjust the gain to prevent the images from clipping (flattening the edges of the graphics). You will now have a system capable of displaying X-Y graphics (no blanking) at up to 12K PPS. This is suitable for entertainment graphics and is especially well suited to dynamic beam effect generation.
Parts list and approximate budget This parts list and budget is based on the LSD1000/Amiga system... costs may vary if another graphics computer/software combination is used
Since this original article was written, new equipment and technology has become available at reasonable prices. Here is an update: Galvos: There are now two excellent low-cost options available:
Lasers: New green DPSS laser diodes and modules are available at reasonable prices. They operate at 532 nM which is very close to the peak of the spectral sensitivity of the human eye. Thus a 5 mW 532 nM laser appears as bright to the eye as a 15-20 mW HeNe laser so you get more "bang for the buck". Many of the lower power DPSS lasers also have a modulation input that allows you to vary the brightness of the laser. This can be used for blanking when projecting graphics from a graphics system that supports blanking and eliminates the need for an external blanking device cutting small projector costs. DPSS modules and drivers are available from MediaLas Graphics: There are now two additional choices for low cost graphics systems:
Most of the information and ideas in the Hobby Archives have been contributed by hobbyists and experimenters. If you have any comments or ideas to share, please contact us by E-mail. DISCLAIMER: Some of the information in the Backstage area is provided by the persons or companies named on the relevant page(s). Laser F/X does NOT endorse or recommend any products/services and is NOT responsible for the technical accuracy of the information provided. We provide this information as a service to laserists using the Backstage area. [ Introduction | Hobby Archives | Hobby FAQ | Laser Construction ]
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