Difference between revisions of "Adam's SSY"
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Latest revision as of 23:07, 11 May 2013
First of all great thanks to Bill Jensen – without his works on SSY1 I wouldn’t catch pulsed laser bug. Thanks Bill
Here is some information about my homebuilt pulsed laser. I named it YAGna (polish girl’s name, if you visit Poland most of our highlander’s daughters will be Jagna ). YAGna uses SSY1 Nd:YAG laser capable of giving 170mJ; 4ns; 1064nm pulses. It wasn’t built for taking portraits – rather for shooting small objects (insects, splashes, falling drops of quicksilver or Ga-In alloy).
Right now I’m running SSY1 just above lasing threshold (2*230V*sqrt(2) = 644V at main cap, which gives something like 6,7J of energy). For two reasons – I’m still using original polymer q-switch which is delicate, at this power level both flashlamp and KTP will last forever. And at lower energy levels beam quality is better (I hope there is less unwanted longitudinal modes). At 6,5 J I get up to 38mJ of IR, after conversion and filtering unconverted IR (a filter from a dead VHS camcorder) I have 8-15mJ of 532nm light. YAGna is equipped with Brewster window to increase conversion efficiency. Conversion efficiency is low since KTP is not working near its destruction limit. It is better for the crystal.
YAGna standing on her 3 BLACK legs Tika looking suspiciously at YAGna. Originally there was a rebreather inside the box (used in coal mines).
Front side of the laser. A diverging lens, piezoelectric lighter on top (for firing flashlamp) and 3 wing-nuts for adjusting the tilt of KTP crystal. The case is sealed with black electrician’s tape (the tape is black, not the electrician ) to prevent the optics from dusting.
Inside YAGna. From left to right – KTP kinematic mount (rotation + tilt), pulse forming network, SSY1 laser on its breadboard, voltage doubler (based on 2 microwave oven HV capacitors and 2 HV diodes), 24V power supply (for PFN1s vacuum relay – after depowering the main capacitor is discharged) and an aligning laser (which ceased to work after 20-30 shots – maybe 0,1% of IR coming out from HR was sufficient to destroy the diode after focusing). As you cans see there is still plenty of room inside, so an amplifier stage, additional PFN1 and trigger board will fit. Case dimensions are something like 30x20x10cm.
Diverging lens, KTP mount, PFN1 network and SSY1 laser. The lens is slightly off-line to avoid backreflections (or rather because there were some problems with gluing )
KTP mount. The crystal is glued inside brass block with thermoconductive glue. There is a 5mm tungsten iris in front of 5x5x5mm KTP crystal.
SSY1 Nd:YAG laser. Attached to a breadboard using magnets.
Beam shape after diverging. Photo was take before I mounted the tungsten iris.
Since now I was shooting small (up to 4x3cm) test holograms (at 6,5J), but I got a holo showing entire face profile from Bill (taken at 15J).
You can see some of my holos at YouTube:
Approximate cost of YAGna so far is around $400 (KTP acosted $250).
I think minimalist’s version of YAGna (KTP salvaged from a dead DPSS pointer) could cost below $200.
What I’d like to improve in YAGna:
- add amplifier stage(s) – 2 SSY1s are already waiting to be used.
- add spatial filter (1m focal length, 0,5mm DIY tungsten pinhole).
- add trigger board and a laser photogate to make holograms of splashes.
- divide YAGna in two – laser head and PSU on separate boxes.
- make YAGna portable to make holograms outdoors.
- whatever else imagination allows