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True black carbon in diamond from an image

  1. Jul 27, 2012 #1
    I have difficulties in finding the true black carbons in a diamond from an image.

    Since diamond has a high refractive index of 2.42, it has a critical angle of 24 degrees such that total internal reflection can easily occur (total internal reflection causes fire in diamond) . Now I have taken an image, my main focus is on black carbon. I want to solely find out the true black carbons without those due to total internal reflection. Is there a way to distinguish the difference or filter out the TIR except for looking at the similarities in shape of the black carbons. This looks like an everyday problem but no one really cares its application, please help~~~~

    Also I will not consider putting the diamond in an solvent of similar refractive index as diamond. And I know that an image cannot tell all black carbon inside the diamond.
    Last edited: Jul 27, 2012
  2. jcsd
  3. Jul 30, 2012 #2
    Please give me some ideas~~
  4. Jul 30, 2012 #3


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    You seem to believe that total internal reflection will result in the appearance of black spots in the image that results from looking into a facetted diamond.

    As I understand it, working from first principles on the assumption of a convex diamond, total internal reflection will never result in any external viewing angles becoming inaccessible to light originating from a given point in the interior of the diamond.

    It follows that there are no points in the interior of the diamond that are not illuminated by light originating at an arbitrarily chosen point source.

    So I just don't get how you think that black spots can result from total internal reflection.
  5. Jul 30, 2012 #4
  6. Jul 30, 2012 #5


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    The pointed-to web page has a picture. It contains no argument for the claim that total internal reflection can cause black spots in the picture of a diamond.

    Perhaps the claim is that internal fracture planes can cause light to fail to pass at certain angles and that this is difficult to distinguish from an inclusion that actually absorbs light.

    That would certainly fail to meet the "convex" premise in the argument that I gave.
  7. Jul 30, 2012 #6
    The easiest way would be to immerge the diamond in a liquid with a high refractive index. But you don't want to do that, for whatever reason.

    The second possibility is to take an image using a wavelength where diamond has a "normal" refractive index close to 1. VUV or X-rays seem to fit the bill, but these are measurements you cannot do in your kitchen sink.

    Walker, W. C. and J. Osantowski, Phys. Rev. 134, 1A (1964) A153-A157.
  8. Jul 30, 2012 #7
    @M Quack
    I am afriad that VUV or X-rays have been considered by my team. Anyway, thanks for your reply.
  9. Aug 2, 2012 #8
    Can anyone provide me some sort of alien technology?
  10. Aug 9, 2012 #9
    Anyone familiar with optical engineering can help me?
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