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DIY Yag Laser

Second in a series of laser experiments

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WARNING: EYE PROTECTION IS REQUIRED FOR VEIWING THIS POST!

Experimental work in progress.
Nd:YAG is neodymium-doped yttrium aluminium garnet
Wave length is 1064 nm. Invisable to the eye.
  • 1 × ND:YAG ROD
  • 1 × Total reflective mirror
  • 1 × T15 Mirror
  • 1 × Copper Parabolic Mirror home made section ##3
  • 2 × End plates

View all 9 components

View all 2 project logs

  • 1
    Step 1

    The Paraboilc Mirror;

    This is a excelent calulator for parabolic formulas.

    https://www.desmos.com/calculator

    I was able to create the profile and the focus point of my desired Parabolic Mirror.

    I then cut 20 of these poly curves on my cnc cutter. The 20 profiles were then assembled into this block and held fast by a 3/8 x 5 " bolt.

    I Cut a peice of 6" copper pipe and hammered it over the form this took a long tiime and I used my bender, clamps and sledge hammer to form the copper very close to the profile.

    The curve was smoothed and 80 grit sand paper was attached to the block.

    The sanding block was clamped into a bench vice. The first sanding took only 7 hours. Dedication to a single task. I used water and oil to assist the honing. Next 240 grit 4 hours of sanding.Then 600 grit. 4 hours. Finally 1200 grit and a polishing paste 12 hours.

    Here is the finished mirror;

    You can see how the light from the flash joins at the focal point.

    The mirror will be nickel plated then gold for ~ 90% reflective surface.

    Brass end plates were then machined on the cnc, and the yag mount hole were cut.

    The end plates held fast by 4-40 cap screws.

    Assembled and the yag rod in position.

  • 2
    Step 2

    This is one of the led modules I am using.

    I have modified it to remove the ears and the corner tabs.

    I will be using the connection inside the module.

    Here the 9 modules are mounted on the heatsink. I used 1" stainless No. 4X40 the extra length will assist in the cooling. This whole unit will sit in an enclosure that will be water cooled.

    I have place the mirror on the top of the led bank to show the alignment.

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Discussions

Electroncatcher wrote 4 days ago point

Very interesting project. So ~2 years from now, is there any followup for this project? Is it finished? Any results? And, how was done ND: YAG laser rod measurements?

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jordanmicahbennett wrote 05/18/2016 at 07:16 point

Where is the detaield schematic, inclusive of board component/configuration?

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Joseph Lavoie wrote 12/19/2015 at 21:40 point

I need to get the test results from my yag laser experiments. 

I will answer these questions with actual lab tests

1. What is the actual output  of the crystal when pumped with all kinds of led sources.

2. What is the efficiency of the conversion.

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Joseph Lavoie wrote 12/19/2015 at 04:24 point

thanks for your comments

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Brian wrote 12/19/2015 at 03:20 point

The white LED modules don't produce any wavelengths within the absorption band of the Nd+3 ion in YAG. You could have 50000 Watts of power worth of white LEDs, and it still won't lase. It is possible to pump with LED's, but the wavelength must be correct, and the emission bandwidth of LED's is quite broad compared to a laser diode, so most of the optical power is wasted, and emission threshold is very difficult to achieve. It would be far less expensive, and more compact, to buy a used 20W or higher power 808nm laser bar off ebay (I have bought them for less than $40). Try to get one with fast axis collimation optics on it.

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A. M. Aitken wrote 11/30/2015 at 12:51 point

Your laser rod looks pink, that's usually a bad sign for this sort of project.  Pink rods usually indicate a Nd doping level that needs flash lamp pumping.  3% versus 0.1% for CW rods from memory.

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Martin wrote 11/30/2015 at 11:20 point

Ideally the YAG crystal is pumped by diode lasers with 808nm wavelength. This gives best absorption and best efficiency. Be careful though, although the 808nm light lookes very dim red it can be dangerous for the eyes.

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Comedicles wrote 11/30/2015 at 03:42 point

The old school method from ruby rod days is to slightly squash the pipe into an oval (an ellipse actually) and place the flash tube - or diodes - at one focus and the rod at the other. All light leaving one focus converges on the other.

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Joseph Lavoie wrote 11/30/2015 at 06:52 point

Yes I will try the squash tube idea on my next try.

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esot.eric wrote 11/18/2015 at 05:37 point

Nice mirror!

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Joseph Lavoie wrote 11/18/2015 at 07:19 point

thanks

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Joseph Lavoie wrote 11/17/2015 at 21:38 point

I will try White , blue,ir leds and get some test results. 9 modules pulsed with 3000 watts of power. Liquid cooled bank array. thanks for your input. Joseph

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zakqwy wrote 11/17/2015 at 21:56 point

Awesome. Wikipedia seems to suggest (referencing Amnon Yariv's Quantum Electronics) that Nd-YAG absorbs best between 730-760 and 790-820nm, might be a good starting point.

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zakqwy wrote 11/17/2015 at 21:31 point

Lots of LED modules! Are you building a continuous YAG laser?? Wicked cool, plus no insanely dangerous cap bank... 

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