Results 1 to 8 of 8

Thread: Anyone here modified a Half-Note 2.5 watt Z-fold 532nm laser into a linear laser?

  1. #1
    Join Date
    Aug 2014
    Posts
    227

    Default Anyone here modified a Half-Note 2.5 watt Z-fold 532nm laser into a linear laser?

    Has anyone here modified a Half-Note 2.5 watt Z-fold 532nm laser into a linear (straight through in a line optics) laser?

    I have a perfectly good Half-Note 2.5 watt Z-fold laser I am thinking of not leaving good enough alone, modifying it into a linear laser for portable use. Has anyone had success doing so with such a laser using the optics it already has in it? Here's a diagram of the unit I have:

    Click image for larger version. 

Name:	06c29508-e4db-4aa0-a93a-0e343cf58064_zpsb053615a.jpg 
Views:	38 
Size:	50.5 KB 
ID:	45917

    I have asked this same question on another forum and received an answer it might be possible by rearranging the optics to this:

    HR---YAG---KTP---OC

    However, the individual commenting wasn't sure I wouldn't end up having to buy more optics to make it work right.

    Here's a photo of the optics inside:

    Click image for larger version. 

Name:	halfnote-beampath.jpg 
Views:	46 
Size:	124.5 KB 
ID:	45920

    Any suggestion pro or against much appreciated. This kind of thing is new to me, I've been in electronics, mostly RF, my entire life, but just learning lasers now.
    Find me on LinkedIn: https://www.linkedin.com/profile/view?id=19751081
    Last edited by Laser57; 01-04-2015 at 22:43.

  2. #2
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,468

    Default

    Do you understand why its configured as a "W" fold? There are very valid reasons for that. Converting it to linear will seriously rob you of power and performance. The V fold locates the crystal at a focal point inside the cavity to increase conversion of 1064 to Green, which is a roughly Quadratic function of energy density in the crystal. There are other more technical reasons as well.

    A "W" is not just a linear cavity folded. It looks that way but there is a complex three dimensional ballet going on inside. The focal length of the mirrors matter. I'd have to measure all the focal lengths and run a stability calculation to see if it would work at all, and that does not in the least compensate for thermal lensing in the rod.

    Designing DPSS lasers is a bit of an art. Simple brute force methods of a short cavity will get you SOME green, but at some horrible tradeoffs.

    What is labeled a "polarizer", is depending on the design, usually a Quarter or Half Wave plate, this is to allow control of the polarization in the crystal. Thus you would also likely have to machine a new KTP mount, to match the polarization states.

    Then buy quite a few adjustable mirror mounts. Usually just removing the epoxy that holds the mirrors will crack at least one of them beyond use. Its a ceramic loaded stable epoxy, and its good to 250'C or more. Its very solvent resistant. So if you bake it off you often end up contaminating the coatings from vapors, if it will bake off at all. In my experience it turns to a hard cement before it fractures, when baking.

    That laser cost 12,000$ new for quantity one in 1990s Dollars, when they first came on the market. You can bet its already optimized for best beam quality and power.

    Considering what it is, there are a lot of people here who would rather buy it from you and let you go get what you want to play with. For 200-250$ of parts on Ebay, You'd have a better chance of getting green photons with a two mirror short cavity.

    If you do work on it, you need protective goggles for three wavelengths. 808, 1064, and 532.

    I service solid state and gas lasers for a living. I have a friend who repairs those for medical use. He calls me all the time for advice about adjusting those when the elements are damaged or worn out. He's very good at alignment(20 years of doing that) and he struggles with Half Notes. Heed my warning. There are less then 10 people on this forum who could take that apart and get it back to spec power. Of those, 5 of them could reconfigure it for "some" green.


    Steve
    Last edited by mixedgas; 01-05-2015 at 06:47.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  3. #3
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    Laser,
    I agree with everything Steve has said. These things might look reasonably straight forward, THEY ARE NOT! Move that KTP a couple of mm one way or another and your green power could cut in half or you might see double or quadruple beams appear. If your goal is portability then for about $1,000 you could get a very compact Laserwave 2W laser that usually outputs 2.5W, comes with a power supply and is about the size of a pound of butter. The chances that the existing optics can be used in a significantly redesigned layout is remote and you will have to spend at least $1,000 on alternate optics with no assurance of success.

    In any case, it's nice to see you're moving up in frequency a bit. Greetings.

  4. #4
    Join Date
    Aug 2014
    Posts
    227

    Default

    Thank you exactly what I needed to know, mitts off on this idea. Perhaps I will just use it as is, less compact and heavier, but it will work. I have 400 dollars into this unit, better I just use this. I already have the 25 amp CC regulator board, TEC control boards, quality goggles good for 808, 1064 and 532nm. I'd go after one of those Laserwave units, but I already have two of these. I'd like to combine the outputs of them, buying a third soon so that will make three.

    Chris

  5. #5
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    For what it's worth the Laserwave DPSS lasers are polarized and so with a wave plate or an actual rotation of the head, you can combine two of them. This is actually what they do internally, when they are selling their 6-8W lasers.

  6. #6
    Join Date
    Aug 2014
    Posts
    227

    Default

    Am I going to have trouble combining the output of these without being able to rotate the polarization? I didn't know, I guess I should have known, I combine RF power using stacked Yagi antennas and they need to be in the same polarization, duh. Now I'm wondering how I am going to do this, shoot them down some fiber optic cable and then twist the fiber to match polarity? If that will work, any recommendations on what to get?
    Last edited by Laser57; 01-05-2015 at 18:23.

  7. #7
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    The Yagis are operating adjacent to each other and so, you are correct they need to operate in the same polarization. Correct me if I am wrong, but wouldn't you optimize the performance of these antennas if they were also spaced to operate in phase as well? Nevertheless, when you are trying to combine the two laser beams, you are trying to overlap them in space as well as make them parallel (collinear). The only way an optical element such as a polarizing beam splitter cube can act on these two beams differently (transmit one and reflect the other into the first ) is if they have orthogonal polarizations. Most of the lasers from the same manufacturer will probably have the same polarization. It is inherent in the birefringence of the vanadate crystal and they will probably mount them similarly, but they don't have to. Get a PBS made to operate at 532nm and see if the two lasers behave identically or reciprocally when you pass them through the cube. If they are identical then a simple 1/2 plate placed in front of one of the beams can be rotated to turn its polarization 90 degrees and your set. That's all. It is done all the time and is not exotic.

  8. #8
    Join Date
    Aug 2014
    Posts
    227

    Default

    Thank you, I will look for such, if needed. On the Yagi's, they are fed in phase with a splitter/combiner and equal lengths of coax and then mounted with enough spacing between them that their individual apertures don't overlap too much, the antennas identical with their mounts centered over one another (or side by side) so they are in phase that way too. Each antenna, depending upon gain, has a recommended spacing. I once had 16 Yagi's all mounted on a H frame which were 12 feet apart, four stacked on each vertical pole and then about 12 feet spacing between each of those vertical mounting pipes X 4. Each Yagi about 17 dBi of gain, total array gain more than 30 dBi at 144 MHz for Amateur Radio Moonbounce. 5 KW into that array produced 5 megawatts of EIRP, I heard my echos from the moon very well.
    Last edited by Laser57; 01-05-2015 at 19:22.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •