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Thread: Polarizing vs Non Polarizing

  1. #1
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    Default Polarizing vs Non Polarizing

    What is the difference excactly? if anyone knows?

    I have been searching and searching for a Polarizing beamsplitting cube for 405nm and over 25mm in size for a long time now but cant find any.

    Today i talked to "Thorlabs" and they have some "nons" and said i could probably use "non Polarizing". but they sound litle unsure.

    any suggestions?


    thnx
    /Rickard

  2. #2
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    Cool

    A Non-polarizing cube will not work to combine two beams of the same wavelength. The non-polarizing cubes are only good for splitting a single beam into two beams. They won't work in reverse.

    The polarizing cube *will* work in reverse, because the diagonal surface in the center of the cube reflects based on the polarization of the incident beam. (Horizontally polarized beams reflect, vertically polarized beams pass through.) It doesn't care if you're combining two beams into one, or separating one beam into it's horizontally and vertically polarized components.

    bottom line - you *need* a polarizing beam splitting cube. If you can't find one that is coated for 405 nm, you can try one that is coated for 445 nm, but you'll probably loose a lot...

    Adam

  3. #3
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    Default

    Hi Rickard,

    I presume you want to combine two 405nm diodes to produce a single beam. In that case you will need a polarizing beam splitter(PBS). A PBS allows a beam with a certain polarization (e.g. horizontal) to pass AND reflect a beam with a perpendicular polarization (e.g. vertical). The idea is to set up the diodes such that one has horizontal polarization and the other has vertical polarization. This will allow you to combine the beams of the same wavelength with a PBS in a way similar to combining beams of different wavelengths with a dichro.

    A non polarizing beam splitter cannot be used to combine beams into a single beam.

    hope this helps.

  4. #4
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    Default

    There is a PBS that is AR coated for 405nm in bluray/hd-dvd sleds. It is rather small though and it's probably not 405nm coated on all faces.

  5. #5
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    Default

    Thnx for all the answers. thnx thnx thnx.

    Really strange that Thorlabs said it would be ok, and i actually talked to the Scandinavian Optics technician as all the sellers where busy when i called. Owell he must have missunderstood me or something.

    Yea i will have to try with a 445nm cube i guess.

    "Tock" yea i know but they are to small as i will have 32 beams to gather up.


    Guess another plan would be to skip the Beamcube entirely and point the beams directly into the Lenses.

    Check pictures below.

    Do you think my "new plan" would work?

    (it will take up much more space in length but i guess i can move some stuff and build it in double-decker)
    Attached Thumbnails Attached Thumbnails 405newplan.gif  


  6. #6
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    Default

    It should work but your output beam will be twice as fat in cross section than with a PBS.

  7. #7
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    if you end up doing this i love you

    lol

    i just received 2 pbs cubes from laser wave and they are 473nm and they do work but you loose a bit of blue. i cannot give exact specs as i do not own a power meter. but i do need to buy one soon as i keep trying experiments and cant give out any real specs
    -Josh

  8. #8
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    Quote Originally Posted by thesk8nmidget View Post
    if you end up doing this i love you

    lol

    i just received 2 pbs cubes from laser wave and they are 473nm and they do work but you loose a bit of blue. i cannot give exact specs as i do not own a power meter. but i do need to buy one soon as i keep trying experiments and cant give out any real specs
    hehe. we will see... im allready saving up for the diodes and reached half the sum.

    But That would be really interesting to find out "thesk8nmidget" i mean if it only takes about30-40% of the power i can live with it. And if i go for a 445nm Beamsplitting cube (havent seen any of them anywhere though) that will be even lower power taken.

    The Diode-Casings (Aixiz) and Heatsinks has allready arrived, now only searching to find a good power supply that can output 6V and about 4.5Amps. to drive them all. The Fans to drive them all has also been ordered but waiting for shippment.

    I will at the end attach some 3D images of my project.

    I have found a company that can make a Cube for 405nm but it cost a fortune

    anyway if anyone have some tips or know some place where i can find a Cube that is 473nm or lower and atelast 25mm wide please post.

    Take care all, and i will take some pictures as soon as i start assemble.

    Thnx

    /Rickard
    Attached Thumbnails Attached Thumbnails fron1.jpg  

    front.jpg  

    front2.jpg  

    front3.jpg  


  9. #9
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    Default

    These are cool pics Thank you.

  10. #10
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    Cool

    Bridge (LaserWave) sells PBS cubes that are coated for 473 nm. They're priced quite reasonably, too. Of course, you're going to have a lot of loss, but it might be worth it to buy one and give it a shot...

    Adam

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