# Double-slit with semi-transparence

1. Dec 1, 2015

### Pizza

Hi,

I have a little question about the double-slit experiment, if this is the right place here, the right category?

When the particles/waves are hitting the wall (the screen): Is that a mesurement as well? I would say Yes, it is, but would like to here a confirmation or a correction.

And --sorry, actually a two part question-- if so, have there been experiments with a semi transparent wall as well with a second wall just behind? And if so, what did the second picture looks like?

Sorry for my poor English. I did not read every thread before, so maybe this is a double question.

2. Dec 1, 2015

### Simon Bridge

Yes.
The particles striking the screen are having their position measured, after having been filtered by position earlier.
The barrier with slit(s) provides a measurement of the component of position in the plane of the barrier.

Pretty much every possible configuration you can think of has been tested.
But I'm not sure I understand what you mean here ... do you mean, what is the result if the barrier the slits are in is semi-transparent?
i.e. cut slits in the glass from a tinted window.

Then you get the effect you'd normally have from slits in a barrier added to the effect you'd normally get just from the tinted glass without slits.
You should be able to figure out what that looks like :)

3. Dec 2, 2015

### Pizza

No, I meant if the screen is semi-tansparent. So, there is a barrier (non-transparent) with 2 slits (transparent), then a screen (semi-transparent) and then another screen (non-transparent).

But I imagine, the picture on the last screen would be similar to the first one. Nevertheless an experiment is better than imagination...

4. Dec 2, 2015

### Simon Bridge

What you get depends on the exact nature of the semi-transparency... say, lightly frosted glass?
The usual interference pattern appears on the semi-transparent one... probably a bit dimmer due to less light being scattered (you understand what screen's do right?).

The transmitted light, in this example, woyld also be scattered.In which case you get, at best, a blurred version of the interference pattern on the final screen. The extent of the blurring depends on the amount of frosting. The pattern would be appropriate for the screen position.

You should be able to reason it out for other kinds of screen combination now.

Screens are actually very complicated in QM... but the effects all average out to give the classical result to a very high degree of accuracy: so it is safe to follow the classical description for them.
Though you could postilate a 1st screen which is basically a random grid of holes on the same scale as the wavelength of the particles...

Last edited by a moderator: Dec 4, 2015
5. Dec 3, 2015

### rootone

That sounds very interesting, I can't even begin to imagine the result.

6. Dec 4, 2015