Design and build first projector, with photos

[weartronics]

Hi PhotonLexicon,

I have design and build my first projector last year between Xmas and NYE for a small show for my friends. I have included some photos to show you here.

The DAC is based on the USB sound card, using ideas from James and Dr Lava. I use Dr Lava's EzAudDac.dll interface to run HE Laserscan and all the excellent available "zoofware" TM. Special thanks to James, Dr Lava and Zoof. I only needed one bias adjustment pot (because all the channels of my sound card have the same bias), and I did not need any gain adjustment pots (because I used fixed 2.5X gain and control it using the software). But I did need twice the number of op-amps, because I needed to generate differential signals for the galvos. I built the DAC to support X, Y, I, R, G, B, even though I am only using X, Y, I currently. I replaced some tall capacitors and cut down the sound card PCB so that the differential amplifier board with the ILDA connector can fit inside the original sound card case.

The projector uses the 100mW 532nm laser from ViaSho, and the CatWeazle galvo system from MediaLas. Unfortunately the modulation for the diode driver is very slow to turn on, which means that one side of ZoofScope is always missing, and sometimes one LaserTennis paddle disappears. Also, I have not learned to tune the galvos yet (they still have their original tuning from the manufacturer from 5 years ago). I built a sealed optics compartment, so I can use the projector with fog and the mirrors never need cleaning (just wipe the front filter). Originally I planned to use the ViaSho "B" type laser with diode driver built in to the laser head, but I used the ViaSho "A" type laser with external diode driver for better reliability, so the diode driver is separate to the projector. I still need to build the side panels for the case and to install the connectors, and to add the shorting relay for the laser diode.

Best regards,

weartronics

The DAC is based on the USB sound card (left), and the amplifier (right) fits inside the same case.

The DAC supports 6 channels (X, Y, I, R, G, B) with differential signals for noise-cancelling.

The projector is very compact, the CD is to show the scale. I haven't
made the side panels or mounted the connectors on the case yet.

You can see the enclosed optics compartment.

You can see the layout of the projector.

The projector is mounted on a pan/tilt tripod.

Laseroids with two eager players at the bottom.

Laseroids after the fog machine is turned on.

One side of Zoofscope is missing due to the slow diode driver modulation.

Zoofscope after the fog machine is turned on.

The end of an exhilirating match of Laser Tennis.

The New Year's Eve countdown. Actually, a test pattern from HE Laserscan.

Who is this fellow? Since the only animations I have are this guy and the flying
goose, he gets a lot of airtime. Very mesmerising after 15 minutes or so.

[Steve Milani]

Superb job!
Congrats!

[soforene]

That's a sweet little box.

[trwalters001]

If I had a nickel for every time I'd said that...

[allthatwhichis]

Very nice build there man! I have to ask though; where is the laser driver?

[Anthony]

extremely nice work

[weartronics]

Very nice build there man! I have to ask though; where is the laser driver?

I originally planned to use the type "B" laser, which has the diode driver internal to the laser head. But ViaSho advised me that the reliability is better with their type "A" laser, so the diode driver is external to the projector. The diode driver looks like this picture. The projector has a D25 connector for ILDA input (from the DAC), then a BNC connector for modulation output (to the diode driver). The projector also has a connector for the laser diode and TEC, which connects directly to the diode driver. I still need to install a shorting relay to protect the laser diode in this instance.

[allthatwhichis]

Why is there a blanking issue? Have you had this looked into?

[weartronics]

Why is there a blanking issue? Have you had this looked into?

I measured the modulation signal in to the driver and the diode signal out of the driver, but the output is very slow to rise compared to the input. Perhaps there is a fault, or perhaps a more power amplifier is required to achieve this blanking speed. ViaSho specifies "10kHz analog modulation" for the diode driver, but I am not sure what this means in practice.

To fix this problem, maybe I will replace the ViaSho power supply with a faster diode driver and a separate TEC driver that will fit inside the projector case. There is lots of space above the galvo amplifier circuit board for other power supplies and drivers. If you have any recommendation for a suitable diode and/or TEC driver, please let me know, I am interested to find some.

[dsli_jon]

Hey Nic -

I have design and build my first projector

Brilliant job, m8! I like the posts... nice use of a threaded-insert... keep up the good werk...

cheers
j