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Thread: IR Filter needed for DPSS laser

  1. #1
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    Default IR Filter needed for DPSS laser

    I need an IR filter for my 30mw green laser. I am not sure what to buy. Could someone give me a link to one that would work?
    Thanks

  2. #2
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    http://www.edmundoptics.com/onlineca...=1328&search=1 this is what you want..............
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  3. #3
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    Yegads! Those are some pricey optics

    For 30mW I'd just steal a IR filter off a old/busted camera. You could also
    look at phosphate glass (heat absorbing glass) for such low powers. (Avoid
    it for higher powers as the glass will shatter)

  4. #4
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    Thanks for the link. I did disect an old digital camera I have but the IR filter is also a lens so it didn't help.

  5. #5
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    PS Is there any harm in these filters reflecting the IR back into the laser?

  6. #6
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    Unlikely for the circumstances where you need an IR filter. It'd have to make it cleanly back past the crystal into the pump. Practically, you'd have to carefully align it and since you usually place the filter before the collimation optics, even if it was aligned perfectly parallel to the source, it would be not pose a problem because the reflection would be defocused.

    P.S. The black'n white quickcams have the right IR filter on them, and they're practically free.
    Last edited by yaddatrance; 02-18-2007 at 18:57.

  7. #7
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    I would need to place the IR filter on the outside of the laser (after the collimation lens) because I don't have access to the inside. Is that OK? You said it should be placed before the collimation lens but I can't do that.

    Also, since I will be sending the laser output through a dichro, do I need a filter at all? I think the dichro might filter out everything but green.

  8. #8
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    Quote Originally Posted by carmangary View Post
    I would need to place the IR filter on the outside of the laser (after the collimation lens) because I don't have access to the inside. Is that OK?
    Most lasers I've seen put it after the lens. If you get a good quality one you might do ok with only 5mm squared, which means cheaper for a given quality, if you can find a source from a largish run. Might be best to negotiate with the laser maker, they might sell one cheap to an existing customer. Especially if they thought you might put a good word in here on their behalf.

    The IR filter on the 250 mW LambdaPro I'm selling is a small one like I describe. It's anchored on a thickish aluminium disk, to get rid of heat. I don't know what it's made of but it's nice, AR coated, some kind of glass. I guess some kind of tinted pyrex or quartz.

    If someone does come up with a source of good ones like this, please post, I want one for my older UG laser, that never had one, and it's years too late to claim one from LambdaPro now. I think a group buy in IR filters would be a success, probably.
    Last edited by The_Doctor; 02-19-2007 at 11:53.

  9. #9
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    Dichros make a great way of eliminating IR if your path is set to avoid transmitting the IR.

    It is unlikely that the IR filter is quartz or pyrex as the former is pyroelectric and polarization sensitive and the latter is a soda-lime glass which has poor spectral characteristics. It's most likely just BK7 or some other schott glass.

    http://www.optics-online.com/irc.asp has very nice prices on their discontinued lines of reflective IR cutoff filters. (7x7 for $12.50) But it's probably a good idea to see if you can get better rates on a group buy and cut the optics into smaller more useful pieces.
    Last edited by yaddatrance; 02-19-2007 at 15:35.

  10. #10
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    Lightbulb

    Hmmm, just found a way to use my video camera to see IR... Well I think it's IR. It's called "Nightshot". This is the same 30mW from Aixiz you have...

    No nightshot...


    nightshot...


    NNS


    NS


    NNS


    NS


    Looks like some goes past, or over my first dichro, and then most of the rest gets reflected back to about the same spot off the next dichro, and a little goes around the second dichro and onto the wall behind the scanners. I checked around and I guess I'm relativly safe. I have been using an anti static bag I cut up as a "blanket" over the two dichros since I knew where it had to be. This just confirmed that and that the bag is a fairly good material to "mask" the IR, or keep it confined. Now that I have physical proof I wonder if I can get a reply from Chuck at Aixiz. Still need to get a filter though...
    Last edited by allthatwhichis; 03-01-2007 at 03:12.
    Love, peace, and grease,

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