Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18

Thread: Mixing 635nm and 660nm

  1. #11
    Join Date
    Nov 2005
    Posts
    84

    Default

    Well I was thinking about this a bit more, and I figured I'd better just try an experiment...

    This IR filter was intended to block IR from a color CCD, but it seems to work great as a general purpose high-pass filter.

    Here's the 632nm passing through the filter (I don't have a 635)



    Now here's the 660 added in. I left them misaligned so you could see the two beams


    The key was to get the angle right, which turned out to be about 30 degrees



  2. #12
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Thumbs up Mixing 650 nm with whitelight beam that already has 635 nm in it...

    Quote Originally Posted by aijii View Post
    Easy huh ?
    So find somebody that makes the filters then
    Wonder if edmund could help out here...
    hehe... I'll bet you *could* get such a filter made, assuming you had enough money to throw at the problem. And yeah, Edmund would probably be the first place I'd try. (Maybe a telescope manufacturer too? Meade, or Lumicon maybe?)

    But I don't know if it would be worth it when you can just put the 650 nm laser last in the chain and avoid the need for such a complex "notch filter" dichro in the first place.

    On the other hand, Eyecage - your experiment is really quite interesting! Honestly, when you first explained it I thought to myself, "There's no way that's going to work!" But your pictures proved me wrong!

    Have you checked power levels before and after the IR filter to see how much 650 nm red you're loosing off that filter? Because if the loss is low, then you've come up with a very inexpensive way to mix 650 with a whitelight beam that has 635 in it... Very cool indeed! (Details please!)

    Adam

  3. #13
    Join Date
    Nov 2005
    Posts
    84

    Default

    I haven't measured it, but the loss looks relatively low.

    For sure, there are small waste beams that are produced off the filter (one 632 and one 660). If I change the angle a little bit either way, one of the waste beams grows in intensity, while the other shrinks. I would guess that they're both about 10 percent lossy.

    I'm sure with something more specialized (with just the right coatings) you could do better.

  4. #14
    Join Date
    Nov 2005
    Posts
    84

    Default

    One other comment on this particular filter...

    Due to lack of the proper AR coatings, blue and green both take the same ~10 percent hit. So this has an impact on ordering:

    If I really wanted to conserve red, I would put both reds at the end of the chain, and have the high-pass filter be the last optic. The downside would be some loss on the blue and green.

    Otherwise, if I could afford to lose some red, I'd combine the two reds first, then use the typical dichros to add in the blue and green down the chain. This way you get to keep more blue and green but sacrifice some red.

    I'll see if I can get the part number or other info about these particular filters, in case anyone's interested.

  5. #15
    Join Date
    Jan 2007
    Location
    Peking
    Posts
    1,207

    Smile

    Quote Originally Posted by dave View Post
    Does anyone know where i can get a suitable dichroic to combine these two wavelengths?
    There is some difficult to do this work.
    As you know, 635nm ,650nm,only 15nm different.
    The flim bandwidth less than 20nm isn't easy!
    Maybe someone coating for optics communication equipland can do this work. But that is so expensive!

  6. #16
    Join Date
    Jun 2005
    Location
    SoCal
    Posts
    508

    Default

    They most certainly do make a narrow band dichros... We have one on our white diode system to combine the 635 and 650 beams. Unfortunately these mirrors are pretty expensive (~$200) as they are not "off the shelf" and I haven't run across them as surplus anywhere. Most optics shops can get them made quickly as needed though. I bet if you order a large quantity, the prices would be reasonable. ($15 for a 1"x1") I've also seen narrow bandpass dielectric mirrors. If anybody contacts China to get a group buy going, I'd certainly go in on it!



    We're also looking at swapping the 655's out with 4 of marconi's 200mW's.
    Last edited by yaddatrance; 02-10-2007 at 19:56.

  7. #17
    Join Date
    Oct 2005
    Location
    Melbourne, Australia
    Posts
    678

    Default

    Yadda, what is under the hood of the 635nm module in your whitelight ? Is it just like an Arctos, but with 635nm diodes ?

    Also - are the 635nm and 655nm seperately modulatable, or are they both tied together to operate as one red channel ?
    Last edited by aijii; 02-11-2007 at 16:51.
    Now proudly stocking and offering the best deals on laser-wave

    www.lasershowparts.com
    http://stores.ebay.com.au/Lasershow-Parts

  8. #18
    Join Date
    Jun 2005
    Location
    SoCal
    Posts
    508

    Default

    They're just like an arctos with a slightly different layout to combine 4 diodes... The two reds are modulatable seperately... I ended up tying them together once the original curiosity wore off as during a show the differences in wavelengths are subtle due to how the eye adjusts...

Posting Permissions

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