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Thread: Beam corrected with minimum optics

  1. #1
    Join Date
    Feb 2008
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    Default Beam corrected with minimum optics

    After many prototypes and broken mirrors i have built a simple reliable mount to correct the beam profile on these high power 445 diodes. Right now the optic does about 95% reflection at 45deg.

    I know many will not like the idea of placing the optic 8-24 inches from the diode. However in most projectors finding a path of at least 12-16 inches shouldn't be too hard.

    Basically this mount bends a mirror mechanically to correct the beam.

    Here are some pics of the optic in action. The two spot pictures are uncorrected and corrected with a diode to optic distance of 16". The diode collimator lens is a asphere with 2.39 mm BFL. The spots are 48 feet from the correction optic. Note: I had to use the black card because my camera wouldn't focus on the reduced spot.



    Here are the pics...
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    Last edited by logsquared; 08-25-2010 at 16:12. Reason: spelling

  2. #2
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    I had some protos made up for a few parabolic collimation experiments some time ago....this may be a good excuse to break out those new mirrors and see what happens. Nice to see some new twists on an old issue.
    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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    Forgot the picture of the test set-up. The correction optic is at 90deg here but could be turned to accommodate constraints inside a projector.
    Click image for larger version. 

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  4. #4
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    Default

    Very nice, innovative use of a curved mirror.

  5. #5
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    Quote Originally Posted by logsquared View Post
    Basically this mount bends a mirror mechanically to correct the beam.

    Have you cut a curve in the ally or are you using spacers of some kind to bend the mirror ?
    What is the substrate thickness of the mirror ?
    Are they dielectric or just front surface ?
    What collimator optics are you using ?
    Can you combine this with a knife edge adjuster recalculate the collimator optics for a few mms instead of 15 cms, do all the testing, organize a GB and sell me few real cheap ?

    Only if you have the spare time , naturally

    Great idea ! Why didn't I think of that?

    Cheers

  6. #6
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    Quote Originally Posted by catalanjo View Post
    Have you cut a curve in the ally or are you using spacers of some kind to bend the mirror ?
    What is the substrate thickness of the mirror ?
    Are they dielectric or just front surface ?
    What collimator optics are you using ?
    Can you combine this with a knife edge adjuster recalculate the collimator optics for a few mms instead of 15 cms, do all the testing, organize a GB and sell me few real cheap ?

    Only if you have the spare time , naturally

    Great idea ! Why didn't I think of that?

    Cheers

    What can't be seen in the pictures are adjustment screws on the back of the mount. These screws allow the aluminum face to bend. This intern bends the front surface mirror. This feature makes the focus adjustable. IMHO this feature makes it better than a telescope. The mirror substrate is glass with a dielectric broadband coating. I use the SG-2 lens for best results.

    I have successfully knife edged 2 diodes together. The trick is to put the knife mirrors as close to the diodes as possible (2 diodes is the max you can knife together and fit on a set of 3mm mirrors with out prisms). I then put the corrector optic 18 inches from the diodes. What happens made me scratch my head for a minute. Basically, I ended up with two spots where the were perfectly overlapped before. This makes sense because bent mirror focuses the beams independently. Because the 2 emitters are physically spaced apart the dots in the far field are as well. To correct this I simply adjust the knife mirror until the spots are ontop of each other again. But, because we can't beat physics the spots at the exit actually have to get further apart.

    Normally I'm all about giving all the details about a idea or project. However, I am one of the suckers who bought several blue diodes of ebay for $500 to find out like 5 days later where they came from. Also, I have invested many hours into making this idea work. I have gone through at least 15 different mount designs and countless broken mirrors to get to a working model. I do have the mounts for sale (see the sale part of this site) if you want to try one out. I think its a good deal considering you can achieve .5mRad with minimal effort.

  7. #7
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    Kniveedging close to the diodes as possible? Then you should try these

    With these mounts you can as close as you want because the feet is at the back of the mount

    Great to see that there are laserist who try a different aproach.
    Attached Thumbnails Attached Thumbnails P1080607.JPG  

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