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Re: Question about Barnes' experiment |
| Name: |
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Marshall Barnes |
| Date Posted: |
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Mar 3, 04 - 5:25 PM |
| IP Address: |
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66.213.45.120 |
| Message: |
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John:
Ed pretty much got it right. However, to be exact, the table doesn't appear to be translucent because essentially it is the "background". Light striking it is reflected back at a bright enough intensity so as to not be effected by the diffraction film.
As for what it is, 'diffraction film' is a sheet of thin plastic formulated in such a way as to diffract light that penetrates it. It can also produce internal reflection effects. The result is that anything that is seen through it which has a background which is brighter, will appear to be transparent, creating the mirage that the background is visible through it. It is a mirage due to the fact that what is actually happening is that the areas of the background immediately above, below and to the sides of the object being effected, are reflected in front of the object. Thus, if the background is a ball point pen, which is being held completely horizontal to the object as in the photo, the pen will appear to be visible through the object. If the pen is tilted, as the infamous pencil in a glass of water example, the pen will appear "broken", and the mirage of transparency will be ruined.
In the case of the ship experiment, there was no more diffraction material used than before. The material was placed in front of the camera. There is no need to place the material completely around the object unless the intention is to see it from all sides.
As far as where I got it, that was American Paper Optics in Memphis, TN if I remember correctly. It's been over 10 years ago.
I hope that helps.
-Marshall Barnes |
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