Looking for a >1Joule YAG Laser head

[wickedALEX]

Hi, I'm looking for a not too big YAG laser head.
It should come form the EU.

 

[ElektroFreak]

A YAG head producing greater than 1J per pulse isn't a very small system.. in fact it's pretty freaking huge. What exactly are you looking to do with it?

 

[Daedronus]

1J is not that big of a deal....especially if you don't mention pulse width. ssy1 can probably do it with a few ms pulse width.

The electrical to optical for pulsed nd:yag is about 1%, so you just need about 100-150J in the flash lamp.

But yes, once again....why 1J?

In one of my videos you can see what to expect from a relatively medium sized yag laser at 80 and 400J of electrical.

Edit:
It will probably be over by the time you read this, but here are a few nice laser heads:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390185212764&ssPageName=STRK:MEWAX:IT

....they will need new flash lamp, originally I think they had arc (not flash) lamps. But the rods are nice.

 

[ElektroFreak]

SSY won't make near 1J.. maybe 100mJ if you're lucky. 1J is a damn big pulse.. I don't own an SSY, but I don't think you can set the pulse duration to be long enough to make 1J of total output energy.

 

[Daedronus]

There are two limits, the amount of energy the flash lamp can handle, and the saturation of the nd:yag crystal. If the PFN delivers long pulses in the flash lamp, the lamp will hold (that is it won't explode).
There are no problems whatsoever to get a PFN to discharge in 3-4ms. You put in the 100-150J of electrical, about 1J will come out.

It's not really a big problem, unless you specify the pulse length, 1J in 10ns and 1J in 4ms are worlds apart.


YouTube - ND:YAG laser BURNITRON
Most of the interesting bits are after the middle.

 

[ElektroFreak]

Sounds like you've got firsthand experience.. I was merely sourcing Sam's Laser FAQ for my info. Quote regarding the SSY-1 from one of the best and most experienced hobbyists around:

• Beam characteristics.
  
  • Wavelength: 1,064 nm.
  • Divergence: A few mR (not yet measured).
  • Quality: A simple positive lens will focus the beam to a microscopic spot.
  • Output energy: Estimated between 10 and 50 mJ. It is at least equal to "1 Alcoa". The laser will punch a hole in kitchen-strength aluminum foil when focused (but doesn't do razor blades using the 15 J PFN). Over 100 mJ is possible on "lively" units up at 900 V on the PFN1. However, repeated operation at these energy levels tend to destroy the Q-switch and adjacent rod AR coating.
• Lasing medium.
  
  • Type: Nd:YAG rod, AR coated ends.
  • Rod diameter: about 4 mm.
  • Rod length: about 50 mm.
  • Lasing threshold: less than 7.5 J (100 us pulse duration).
• Flashlamp - This looks similar to an ordinary photographic variety, perhaps somewhat higher quality, but not the very high quality EG&G FXQ style lamp. It may be a FXQG-264-1.4 or FXQSL-559-1.4. See the section: Shawn's High Energy Experiments with the SSY1 Laser Head.
  
  • Arc length: 35 mm (about 1.4 inches).
  • Outside diameter: 5 mm.
  • Inside diameter: 3 mm.
  • Overall length: 75 mm.
  • Ko impedance parameter: 16 ohms-amp0.5 (estimated).
  • Flashlamp envelope: quartz.
  • Electrodes: machined solid tungsten.
  • Minimum voltage: less than 300 V.
  • Maximum voltage: greater than 1,000 V.
  • Maximum energy input at 100 us pulse duration: 25 J (guessed!).
  • Recommended energy input at 100 us pulse duration: 15 J at 900 V.
  • Maximum average power input: 7 W (estimated).
  • Trigger: External trigger electrode (white wire).

 

[Daedronus]

Here is a nice calculator for flash lamps:
Fenix Technolgy : Fenix Calculator

If we enter the ssy1 arc length, and bore, 150Joules, and 3ms pulse length we get 18% of the explosion energy, this is perfectly acceptable.

 

[ElektroFreak]

If we're hitting the rod with 150J, it seems like we're a ways outside the recommended incident pump energy to me, thereby risking a drastically shortened lifetime..

 

[Daedronus]

nd:yag damage threshold....700 mega watts/cm2
150joules in 3 miliseconds....50 kilo watts? nope, you won't do anything to the rod.

Anyway, even a red LOC diode will put out 1J, if it's running at 200mW in a 5 seconds interval it will put out exactly 1 joule. 1 Watt = 1 Joule/1 Second.

My point wasn't that you should buy a ssy1, my point was that joules mean nothing unless you also tell the time or the application.

 

[ElektroFreak]

what about coatings and the q-switch? They are far more susceptible to damage..

True enough about time period..I was just sticking to a typical q-switched YAG time period, in the range of nanoseconds to microseconds.

 

[Laser_Ben]

To get 3-4ms pulses, you will need to remove the Q-Switch as he said above. Coatings on the rod are likely fine, the peak power when Q-Switched is higher. Mirrors are fine, they take a lot of energy.

 

[ElektroFreak]

I missed the "remove the q-switch" part.. in fact I'm still not seeing it. Interesting learning experience for me here in this thread, though.. makes me want an SSY.