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Thread: Optic to combine lasers !?

  1. #1
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    Default Optic to combine lasers !?

    To make a long story short.
    I need some optic to combine RED+RED
    I got 2 red modules, and wonder if I can combine them togheter so there will be one FAT red beam ?

    And them put it into the green beam that already is FAT
    Then I will get a bigger and fatter Yellow beam ? :roll:

    I want something cheap and easy, maybe a search at eBay ?
    But what do I type in to search ? :roll:


    (if you got some stuff that you feel you dont need so plz let me know)

    Thanx for any answer

  2. #2
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    Default

    Hey Liteglow,

    Well Yes,.. it can be done

    Its a bit more involved than what you think

    First you will need a polarized Beam Splitter / Combiner cube
    There are some on ebay quite recently ..
    You will have to align the polarizations up correctly and than some.
    Plus there is some loss ..up to 50 percent depending on the
    choice of cube..
    Also , you must be careful NOT to reflect the beam back into the diode as this will destroy it.
    Its tricky...
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  3. #3
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    Default

    Oh...

    50% loss !
    So that`s like 200mW of laser = 100mw combined ? lol :? :?


    Well, as I se it from here I seems like a bad idea to mix the 2 red modules !?
    I actually think i got a beamsplitter\cube from a DVD burner !!?!


    Well thanx for the info

  4. #4
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    Default

    Quote Originally Posted by marconi
    ...up to 50 percent depending on the choice of cube..
    Sounds more like a real 50:50 beam splitter cube ;-) Well, alignment may be vital, but just last weekend I saw a nice pol cube adding 2x ~80 mW red from two DVD burner diodes quite effectively (you'd expect to see bright waste beams if it's not working properly)...

    Good pol cubes are usually a litte more expensive, but I'm curious about your DVD burner's cube experiments. My burner just had dichros, no cubes...

    Cheers
    Christoph
    Popelscan is still alive - check out here!

  5. #5
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    Default

    i will find the parts and take some pictures

  6. #6
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    Default

    Yep, already discussed the burner option in another forum... Seems the burner manufactures are not very willing to pay for patents of other companies, so they all use different methods to align the beams.

    Samsung uses (pol?) cubes, LG does not ;-)

    Cheers
    Christoph
    Popelscan is still alive - check out here!

  7. #7
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    Default

    Hey Christoph

    Do you know which Samsung model they pulled the cubes from
    for that experiment?
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  8. #8
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    there was a qube in on CD\DVD rom i got !
    But the cube was no god, nothing happend when i tryed to combine a laser.

    But in the other DVD there was a mirror\glass mounted like this \

    And that glass did almost split my green laser 50\50%

  9. #9

    Default

    The cube there is a narrow bandpass cube.

    reflects 780nM and passes 650nM. Not really good for anything other than steering two different lasers when needed.

  10. #10

    Default combining

    Hey liteglow,

    I would consider using an approximate spatial combination with a mirror only setup. I have used it a few times with some success. The arrangement looks like this:
    Code:
                 ^   
                 |
                 |
    === ------->/     laser 1
                 |
                 |
                 |
                 |
                 _
                | |   laser 2
                | |
    (the slash is a mirror at 45 deg)

    This is approximate because you can't get the beams exactally aligned, but you can get really close. Consider:
    1. At the laser apperature, the beam diameter <2 mm
    2. With careful mirror positioning, you can get <1 mm distance between the two laser beams (there is always some distance)
    3. Then the distance between the centers of the beams is < 3mm
    4. At a distance of 50 feet beam divergence makes the diameter of a single beam about 20mm

    This means that at 50 feet the beams overlap over 90%, which is good enough for most purposes. You can also angle the mirror slightly inward, so that at some fixed distance (say 100 ft) the beams converge 100%, and at twice that distance the beams are back to their original orientation, with <3mm distance between the centers of the beams. At 200 ft, the beam diameters might be 40mm, with makes the 3mm distance even more trivial.

    I've used this setup to successfully combine a red with a green, and I can tell you that at 12 feet away from the laser heads the beam looked like a single yellow beam. The effect continued to work until about 300 feet away, at which point you started to see the the separate red and green beams again. With subtle adjustments to the mirror the useful range can be extended much further while sacrificing some near range alignment.

    This setup is better for combining same-color beams because any misalignment is less noticible, and because there is almost no power loss like you get with beamsplitters or dichros.

    It helps to have a thin first-surface mirror, or (ideally) one where the edge is beveled 45 degrees inward, because the mirror thickness limits how close you can get the two beams.
    Code:
                        || 
                        || 
                        || 
                        || 
                        || 
                        ||  
    --------------------/|
                      /  |
                    /    |
                  /      |
                         |
                         |
                         |
                         |
    (closeup of two beams at mirror. Again, the slashes represent a mirror at 45 deg)

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