GRED: Double slit with fast lensless video screen

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What pattern appears on the fast video screen?

An interference pattern.
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No interference pattern.
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Waffles the Wonder Llama.
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Total votes: 1372

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RJN
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GRED: Double slit with fast lensless video screen

Post by RJN » Mon Jun 14, 2010 7:17 pm

Guess the Result of the Experiment of the Day (GRED)

A classic double slit experiment is done with light (photons) that creates an interference pattern on a distant image screen. The experiment is repeated, except now the image screen is replaced by an extremely high speed video sensor array, without a lens. The video sensors act just like the old image screen, except now each frame of the video is precisely time tagged. The time of release of single source photons is also recorded precisely. Adding all of the frames, what pattern accumulates on the video camera's screen?

Here is an ASCII schematic:

Code: Select all

                                                            
                               |                                |
     s                         |                                |
                               |                                |

    Photon                   Double                            Fast
    Source                    Slit                            Video 
                             Screen                           Screen
Aspect to consider: if the precise time-of-flight time for a photon is known, won't it be possible to compare this with the time-of-flight it would take for this photon to go through each slit, and therefore determine which slit this photon went through? And if such "which-path" information is known -- won't this destroy the interference pattern?

Please do NOT post any answers or comments with spoilers here. Answers and comments with spoilers are encouraged in GRED Answer post here: http://asterisk.apod.com/vie ... 30&t=19826 . Please check back there later -- what I believe to be the correct answer will be posted there a few days after this initial post.

Comments or questions here -- without spoilers -- are OK. In particular, questions about the experimental setup are OK.

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alter-ego
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Re: GRED: Double slit with fast video camera

Post by alter-ego » Tue Jun 15, 2010 3:54 am

Robert - Just to clarify, I assume there is no "sharp-eyed" lens on the camera. True? I.e. the slits are not resolved?
A pessimist is nothing more than an experienced optimist

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RJN
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Re: GRED: Double slit with fast video camera

Post by RJN » Tue Jun 15, 2010 4:09 pm

Excellent point, ae. This time I was assuming a lensless system. Therefore, picture the video camera with no lens attached -- a bare photosensor array. I have now clarified this in the initial posts. - RJN

brazosastro

Re: GRED: Double slit with fast lensless video screen

Post by brazosastro » Wed Jun 16, 2010 10:02 pm

This sounds like something that could be done pretty easily (i.e., no LHC needed).

M

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Star*Hopper
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Re: GRED: Double slit with fast lensless video screen

Post by Star*Hopper » Sat Jun 19, 2010 9:43 am

You're kidding, right? That's so simple, I'm gonna let my driver back there answer that.
"Perhaps I'll never touch a star, but at least let me reach." ~J Faircloth

jfreed27

Re: GRED: Double slit with fast lensless video screen

Post by jfreed27 » Sat Jun 19, 2010 11:56 am

How will "knowing" effect phenomena?

webo

Re: GRED: Double slit with fast lensless video screen

Post by webo » Sun Jun 20, 2010 2:32 am

I'm not sure from the reading of the question just how the video screen is timed with respect to the light signals?
Are they simultaneously opened with the/each signal? Is this a "photon entanglement" setup?

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alter-ego
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Re: GRED: Double slit with fast lensless video screen

Post by alter-ego » Sun Jun 20, 2010 4:16 am

webo wrote:I'm not sure from the reading of the question just how the video screen is timed with respect to the light signals?
Are they simultaneously opened with the/each signal? Is this a "photon entanglement" setup?
I believe you should consider this problem a "thought experiment" where you can ignore details of how timings are done. Consider the frame collection to be fast enough (with a timestamp for each frame) to allow "precise" photon arrival times. The photon departure time is also assumed to be known, but the detection method is not mentioned. Is this a photon entanglement setup? Per se, no. My view of this problem is you are equipped with "ideal" measurement equipment.
A pessimist is nothing more than an experienced optimist

aeqel

Re: GRED: Double slit with fast lensless video screen

Post by aeqel » Tue Jun 29, 2010 12:20 pm

jfreed27 wrote:How will "knowing" effect phenomena?
Think superposition I assume.

madmagician

Re: GRED: Double slit with fast lensless video screen

Post by madmagician » Tue Jul 20, 2010 9:48 am

At what rate are photons being released? Does it matter if there is only one? [Or 1024, or a practically continuous stream].

shoreline1

Re: GRED: Double slit with fast lensless video screen

Post by shoreline1 » Wed Jul 21, 2010 4:48 pm

Well, I do like llamas.