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members:dennisdraheim:projects:layzor [2013/06/19 22:47]
dennisd |
members:dennisdraheim:projects:layzor [2013/06/20 17:34] (current)
dennisd [Construction] |
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| =====Overview===== | =====Overview===== |
| This project started when [[members/tomgralewicz|Tom Gralewicz]] showed me a pair of X-Y galvanometers in his junk box. I decided I could make a laser light show projector with them, so I browsed around on the web and came across several designs based on hooking a USB sound card to a computer to generate the signals. Thus was LAYZOR!!! born. | This project started when [[members/tomgralewicz|Tom Gralewicz]] showed me a pair of X-Y galvanometers in his junk box. I decided I could make a laser light show projector with them, so I browsed around on the web and came across several designs based on hooking a USB sound card to a computer to generate the signals, and some [[http://marcansoft.com/blog/2010/11/openlase-open-realtime-laser-graphics/|software]] that had a really cool [[http://www.youtube.com/watch?feature=player_embedded&v=m_CHXwXvWvs|demo]] of programatic control of a laser using this technique. Thus was LAYZOR!!! born. |
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| =====Construction===== | =====Construction===== |
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| LAYZOR!!! uses a [[http://dx.com/p/external-5-1-channel-usb-2-0-sound-card-optical-audio-adapter-black-41289|USB 5.1-channel sound card]] as a DAC to generate signals to a set of galvanometers, which deflect the beam from a green laser pointer in X & Y to draw animations on a screen. I've used the channels as follows: | LAYZOR!!! uses a [[http://dx.com/p/external-5-1-channel-usb-2-0-sound-card-optical-audio-adapter-black-41289|USB 5.1-channel sound card]] as a DAC to generate signals to a set of galvanometers, which deflect the beam from a green laser pointer in X & Y to draw animations on a screen. I've used the channels as follows: |
| * Channel 1 - X galvo (galvo 3) | - X deflection (galvo 3) |
| * Channel 2 - Y galvo (galvo 4) | - Y deflection (galvo 4) |
| * Channel 3 - Left stereo output (to speakers) | - Left stereo output (to speakers) for synchronized audio |
| * Channel 4 - Right stereo output (to speakers) | - Right stereo output (to speakers) for synchronized audio |
| * Channel 5 - Shutter / modulation galvo X | - Shutter / modulation X (galvo 1) |
| * Channel 6 - Shutter / modulation galvo Y | - Shutter / modulation Y (galvo 2) |
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| The sound card generates a 2.4±1.2v signal, whereas the galvanometers expect a -10-10v input, so the signal has to be routed through a correction amp to offset it by -2.4v and amplify it by about 8x. The correction amp boards are based on [[http://laserboy.org/graphics/huge/laser_h_95.jpg|this schematic]], modified slightly to use the components we had on hand at MMS. | The sound card generates a 2.4±1.2v signal, whereas the galvanometers expect a -10-10v input, so the signal has to be routed through a correction amp to offset it by -2.4v and amplify it by about 8x. The correction amp boards are based on [[http://laserboy.org/graphics/huge/laser_h_95.jpg|this schematic]], modified slightly to use the components we had on hand at MMS, as follows: |
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| The laser source is a [[http://www.radioshack.com/product/index.jsp?productId=2767643|Radio Shack green laser pointer]]. Because this is a [[http://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser|diode-pumped solid state laser]], it takes a bit of time (maybe 10ms) to turn on. Thus, I was unable to effectively PWM the power input to modulate it, so I decided to use another galvo pair to aim the beam either at or away from the X-Y galvo. This is shown as Galvos 1&2 in the diagram above. The Y galvo of this pair is just used to center the beam vertically on the X-Y galvo pair's mirrors, but the X galvo is modulated using channel 5 of the USB sound card to either direct the beam toward or away from the X-Y galvos. The beam is passed adjacent to a razor blade (just to provide a nice sharp edge with no diffraction), and can actually be partially occluded by blade to attenuate the beam, giving me an analog intensity channel. | {{:members:dennisdraheim:projects:LayzorCorrectionAmp_schematic.png?nolink|LAYZOR!!! Correction Amp Schematic}} |
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| | The galvos are made by [[http://www.scanlab.de/en/home|ScanLab GmbH]], and use SSV30 amplifier boards. They were originally used in a laser marking system (with a powerful IR laser) for labeling crates as they passed by on a conveyor belt. I managed to find a manual for a similar model of galvos that use the same board on a [[http://wenku.baidu.com/view/25d48bddce2f0066f53322de|Chinese web site]]. From this I was able to figure out the pinout of the connectors, and determined that they needed a ±15v@1.5 amp power supply, and were controlled by a -10v to +10v analog signal. I repurposed four 15v Toshiba laptop power supplies from the MMS Hack Rack to power the two sets of galvos. |
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| | The laser source is a [[http://www.radioshack.com/product/index.jsp?productId=2767643|Radio Shack green laser pointer]]. I stuck with a 5mW laser because I didn't want to risk blinding myself or others. Because this is a [[http://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser|diode-pumped solid state laser]], it takes a bit of time (maybe 10ms) to turn on. This meant I was unable to effectively PWM the power input to modulate it, so I decided to use another galvo pair to aim the beam either at or away from the X-Y galvo. This is shown as Galvos 1&2 in the diagram above. The Y galvo of this pair is just used to center the beam vertically on the X-Y galvo pair's mirrors, but the X galvo is modulated using channel 5 of the USB sound card to either direct the beam toward or away from the X-Y galvos. The beam is passed adjacent to a razor blade (just to provide a nice sharp edge with no diffraction), and can actually be partially occluded by blade to attenuate the beam, giving me an analog intensity channel. |
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| =====Software===== | =====Software===== |
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| The software I'm using is called [[https://github.com/marcan/openlase|OpenLase]], by Héctor Martín Cantero (a/k/a marcan). He describes it on his [[http://marcansoft.com/blog/2010/11/openlase-open-realtime-laser-graphics/|blog]]. | The software I'm using is called [[https://github.com/marcan/openlase|OpenLase]], by Héctor Martín Cantero (a/k/a marcan). He describes it on his [[http://marcansoft.com/blog/2010/11/openlase-open-realtime-laser-graphics/|blog]]. I also played around with the [[http://laserboy.org/|LaserBoy]]. LaserBoy is more geared toward building pre-made images and animations which are then played using an audio player, whereas OpenLase allows me to programatically draw animations in real time with the laser. |
