- #1
Luc B
- 32
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Hello from Belgium. Bruxelles.
In 1815, Fresnel made, with Arago, the experience of Poisson spot. (or Arago spot, or Fresnel bright spot). A bright point that appears at the center of a circular object's shadow due to Fresnel diffraction.
Arago and Fresnel glue a round opaque screen on a glass sheet. And use as light, the sun going through a very small hole. There are some different versions of this experience...
But photo of the round shadow and its bright central point exist... On internet.
What does have seen Fresnel if he has watched in the direction of the light, Hidden by the opaque disc.
His eye so where is the bright central point.
We can make an other experience. Now that we have camera.
Point our camera in the direction of a small light in the distance.
And occult the light at half distance with the edge of an opaque screen.
Does the light stay at the same place (in the same direction...) on the film before disappear.
Thanks for your replies.
Luc B.
In 1815, Fresnel made, with Arago, the experience of Poisson spot. (or Arago spot, or Fresnel bright spot). A bright point that appears at the center of a circular object's shadow due to Fresnel diffraction.
Arago and Fresnel glue a round opaque screen on a glass sheet. And use as light, the sun going through a very small hole. There are some different versions of this experience...
But photo of the round shadow and its bright central point exist... On internet.
What does have seen Fresnel if he has watched in the direction of the light, Hidden by the opaque disc.
His eye so where is the bright central point.
We can make an other experience. Now that we have camera.
Point our camera in the direction of a small light in the distance.
And occult the light at half distance with the edge of an opaque screen.
Does the light stay at the same place (in the same direction...) on the film before disappear.
Thanks for your replies.
Luc B.