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  1. #1
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    Let's design a beam shape in Excel

    This sounds like a crazy idea, but I thought that it is possible to use Excel to design a beam shape and then to have an optic designed that will produce this beam shape.

    So my idea is to have a 1 XM-L optic which will produce a road-friendly beam. Why 1 XM-L only? Because a more efficient use of the lumens (not on the treetops, but on the ground) will allow to use a smaller light.
    Also, it will be easier to calculate an optic for 1 LED

    So here is my attempt at designing a beam shape in Excel.



    It is done with a resolution of 5 degrees and I used conditional formatting to see the light distribution. Also it is close to StVZO requirements.

    If you want to tweak this design, you can download the Excel in the attached ZIP file

    Your ideas on how to improve it are welcome.
    Attached Files Attached Files
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  2. #2
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    So, I am not an optics expert, but how do you get from "here's the beam shape I want" to "here's the reflector/optic I should build"?

  3. #3
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    Hmmm, I went the other way. Put the beam pattern into excel and calculate the illumination on the road.
    Then add another beam, vary the beam angles, the angles between the beams, and the beam intensities .
    See if you can get a nice flat illumination curve.
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  4. #4
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    Quote Originally Posted by Praxis View Post
    So, I am not an optics expert, but how do you get from "here's the beam shape I want" to "here's the reflector/optic I should build"?
    That's pretty easy - I have a reflector design specialist who can run the necessary simulations.
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  5. #5
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    Quote Originally Posted by znomit View Post
    Hmmm, I went the other way. Put the beam pattern into excel and calculate the illumination on the road.
    Then add another beam, vary the beam angles, the angles between the beams, and the beam intensities .
    See if you can get a nice flat illumination curve.
    That sounds complicated. For simulating existing optics I recommend Dialux. It is a free illumination simulation software.
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  6. #6
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    This sounds really interesting. How would such a beam differ from the desired beam for use off road as a bar light? We are not really interested in lighting up the sky there either.

    Zemike. Any chance of getting my clammy hands on a .stp file of such a reflector? I am considering additive manufacturing (3D-printing) for a light. It will be heavier than a couple of Reginas but there could be some design benefits.

  7. #7
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    OK, I think the best beam shape would be a triangle with more lumens the narrower it gets (brightest spot at the top). There is always too much light near the bike and never enough 30 meters in front of you. The eye adapts to the brightest spot in front of you, letting you see even less further away.

    Up to now I found the half cat-eye-reflecter the best.

    I don't know if it is possible, but this beamspape would be quite nice.
    Let's design a beam shape in Excel-beamshape2.jpg
    beamshape2.zip

  8. #8
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    There are different apprcaoches to a good beamshape.

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