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djflatson
New Participant
May 29, 2015

Lens/Rift CAD files?

Hey guys,

I am trying to do some basic tests in my CAD package as far as the OR optics go, but I need to know what the shape of the lens actually is. I know it is an aspherical plano convex lens, but I haven't been able to find any dimensioned drawings of a cross section directly down the center. I don't just want the diameter, but the actual function of the surface and/or just a drawing that I can trace in Solidworks for example.

Thanks for any help you have!

    2 replies

    Fredz
    Up and Coming
    May 30, 2015
    The DK2 lens is not plano-convex but double convex, although one surface is much less curved than the other one. It's not clear if it's aspheric or spherical either, the DK1 lens was aspheric but nothing has been said for the DK2 lens.

    If you don't have special optics equipment your best bet is probably to take a photograph of the lens from the side and try to calculate the surface profile. But if the lens is aspheric your CAD package would need to be able to handle the equation for an aspheric surface profile :



    Manufactured aspheric lenses generally use 4 aspheric coefficients from what I've read on the subject.

    I've tried to find these values for a ray-tracer I developed by taking photos of the surface profile and measuring the dimensions with a digital caliper, ignoring the aspheric coefficients, but that's largely trial-and-error and it's probably nowhere near the real specifications.

    I came up with this :

    DK1 (UltraOptix 7X) (unit in mm)
    Inner diameter : 3.4925
    Outer diameter : 3.66
    Refractive index : 1.4914 (acrylic)
    Front (spherical) :
    - radius front : 10
    - thickness front : 0.335
    Back (aspheric) :
    - radius : 2.5
    - thickness : 0.606
    - conic : -3

    DK2 (unit in mm) :
    Inner diameter : 4.063
    Outer diameter : 4.3
    Refractive index : 1.585 (polycarbonate)
    Front (spherical) :
    - radius front : 12
    - thickness front : 0.25
    Back (aspheric) :
    - radius : 3
    - thickness : 1.25
    - conic : -2.1
    Fredz
    Up and Coming
    May 31, 2015
    I was wrong about the refractive index of the DK2 lens, it's acrylic, not polycarbonate : http://vrtifacts.com/oculus-dk2-lens-characteristics/
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