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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.
    Note: Since this article was originally published on our web site, new products and systems have become available.  We have included these in an Update section at the end of the original article.

 

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 low cost alternative is to use open loop galvos with special drive amps. Open loop galvos such as the General Scanning G124, G114 and G112 have the speed required to do graphics but no position detecting device. When driven by 'Accelerator' type amps, a position signal can be derived from the back EMF in the coils and used to improve the accuracy of the scanners. These type amps are available from Lighting Systems Design Inc. (LSDI) who make the 'Accelerator124' which is optimised for use with the G124 galvos.
    In addition to the amps you will need a suitable power supply. Scanners are bi-polar devices so you will require a bi-polar power supply which can deliver +/- 15 to 18 VDC. As a rule of thumb each scanner will consume one amp of current so your supply has to provide a minimum of 2 amps. Since you may want to add additional items like a shutter or effects wheels later, it is best to get a larger supply (3 to 4 amps) to allow for expansion. The additional cost of the larger supply is often only 15% to 25% more than the small supply and is well worth the extra. You will need to mount the power supply into a box along with the scan amps and any size, position and image invert controls you need. The cables that carry the scan signals from the amps to the scanners should be kept to around 1 meter (3 ft) or less for best results.
    You will require a pair of small front surface mirrors with mounts to fit onto the shafts of the galvos. The usual arrangement has been to have an X mirror of 5 X 5 mm and a Y mirror of 5 X 7 mm. For best performance and to eliminate having to stock different kinds of spares, a pair of 5 X 5 mm mirrors would be best.

Simplified scanning system diagram  

    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.
    HeNe lasers are available from many sources, both new and surplus, and are relatively low cost at powers up to 7mw [7/1000 of a watt]. Prices of HeNe's then escalate sharply with the cost of a 50 Mw HeNe equal to the price of a small air-cooled argon laser. The most popular small argon laser is the '60X' type and there are many used and reconditioned units available.
    A low power HeNe laser is great for experimenting and producing small graphic and abstract images in a dark room. If you want to produce beam effects in a small room you will need a higher power laser such as a small argon laser producing 100 mW or more - in larger spaces you will need a laser with watt or more of power - particularly if you want to make beam effects.

 

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
    LSD1000 format animations, graphics and beam effects can be obtained from Laser F/X or traded with others using the LSD1000 system.  There are some LSD1000 format frames available for download in the Frames Archives section of the Archives and Download area of our site.
    There are also a number of low cost PC based packages available. One that we have seen in action and that offers a number of features is the Laser Illusions system. This has an outboard card that attaches to the parallel port of an IBM compatible computer. You can contact Rick Gebhardt by e-mail to LaserIl@aol.com for more info.

 

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.
    You will need at least 1 Meg of memory to run the software and to hold one bank of 256 images. If you can acquire a computer with 2 or more meg of memory you can hold the software plus three banks of 256 frames in 2 Meg, more with a larger memory.

 

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.

Amiga bi-polar modification diagram

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

  • Two General Scanning G124 galvos [new about $350 US$/ea. - used ones start at $100 US/ea. when you can find them] Sources: General Scanning, LSDI, or New Method Lasers.

  • Two 5 mm square scanner mirrors [new about $50 US$/ea.] Sources: LSDI, Precision Projection (General Scanning sells them but charges too much).

  • Scan head or scan stage [stages can be made by you local machine shop for around $60 US$ but you need to know what you are doing in terms of hole placement].

  • Two Accelerator type scan amplifiers [$150 US$/ea]. from LSDI or New Method Lasers

  • Power supply +/- 15 to 18 VDC at 3 Amps [around $150 to $200 US$] Sources: Newark electronics, Power One, Condor, Hammond.

  • One used Amiga computer with monitor and 1 Meg of memory minimum [cost varies depending on HD and memory - from $300 to $700 US$] Sources: Contact the local Amiga users group, local computer papers, visit Amiga sites on the net such as National Amiga.

  • Modifications to the computer will require some parts and a small project board [$25-35 US$] from local electronics suppliers [Radio Shack or others]

  • Cabinet, cables, plugs, switches and other shop parts that will be needed for final assembly [budget around $150 to $200 US$ to do a good job].


Update

    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:

  • The Catweazle scanners from MediaLas in Germany will go at speeds up to the 30K ILDA standard.  The come almost ready to go with the scanners mounted in the correct relationship on a right angle bracket and an assembled and tuned scan amp that simply needs to have 220V or 110V [switch selectable] power, and scanning signals applied.  The only limitation is that the scanners can not take more than 3 watts of laser power but this should not be a problem in small systems.  The Catweazle scanners are available from MediaLas or New Method Lasers for about $995.00 US$ which is not much more than the "accelerator" system described above but has far better quality and a lot less work to assemble.

  • The Eye Magic scanners will also go at speeds up to the ILDA 30K standard.  They come as a pair of scanners with mirrors and drive amps.  You must supply or purchase a scanner mounts, and you will need a power supply and will have to do a little wiring to assemble them.  Since they use mirrors on mounts, they can be used with lasers over 3 watts in output.  Eye Magic scanners are available from New Method Lasers for about $995.00 US$ which is not much more than the "accelerator" system described above but has far better quality.

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:

  • The LaserMAX program for the Amiga is share-ware and can be downloaded from the Archives and Download area of the Backstage.  You still have to modify an Amiga computer as described above, but this program offers more "bells and whistles" than the LSD1000 program.

  • Rick at Laser Illusions has a new interface card with ILDA output and more sophisticated software for around $500.00 US$.  The system supports full RGB colour output for 16.7 million colours and blanking so it is ideal for those who would like to move up to a more professional systems as funds become available.

 

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. 

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