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Question strange total internal reflection when using polishedbackpainted 

Forum: Processes Involving Optical Photons
Date: 12 Feb, 2010
From: Akira Okumura <Akira Okumura>

Hello,

I am checking the boundary process of the G4 optical with my simulation code. I found that a part of photons are reflected to unexpected directions at a boundary between water (but n=1e5) and air when I set the finish to polishedbackpainted.

This is an image of "polished". http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2010/02/12/23.27-57010-polished.png

And this one is "polishedbackpainted". http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2010/02/12/23.27-3707-polishedbackpainted.png

In the latter image, you will observe that incident angle and reflection angle are not always same.

According to Peter's explanation, http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/305/1.html "polishedbackpainted" is not affected by any roughness parameters. and thus, if I set the refractive index to n=1e5, all photons must be "spike" reflected due to total internal reflection. Am I wrong?

In addition, two of all photons escape from the water tank while it should not be able to escape from the box due to the large index.

I obtained these results with this code, http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2010/02/12/23.27-99178-tectorConstruction.cc.txt

which was modified from the previous my thread post here. http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/309/1/1.html

Is there any my misunderstanding or incorrect code in the attached? Any suggestion, please?

Akira

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1 Note: Re: strange total internal reflection when using polishedbackpainted   (Akira Okumura - 12 Feb, 2010)
(_ Warning: Re: strange total internal reflection when using polishedbackpainted   (Gumplinger Peter - 15 Feb, 2010)
(_ None: Re: strange total internal reflection when using polishedbackpainted   (Akira Okumura - 15 Feb, 2010)
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