slit pattern, vertical or horizontal?

lightconstant

This has already been asked:
http://www.physicsforums.com/showthread.php?t=77835

It is a simple question but I am confused, if the slit or the slits are vertical the direction of the pattern is horizontal or vertical?
Vertical:
|
| |
|
| |
|
| |
|

Or horizontal like in this video:
http://www.youtube.com/watch?v=tu57B1v0SzI
|

| || | | | |

|

At the left is the two slits and at the right the pattern, the first one in the same direction of the slits vertical and the second one horizontal (It should go inside the screen) but It is hard to draw
Which one is it?

jtbell

The bright and dark bands are each oriented vertically, parallel to the slit(s), but they are spread out in a horizontal pattern, perpendicular to the slit(s). This is how I would describe the patterns shown from about 1:00 onwards in that movie.

lightconstant

Well expressed jtbell so is that what it happens or should it be rotated 90 degrees like:

The bright and dark bands are each oriented horizontally, perpendicular to the slit(s), but they are spread out in a vertical pattern parallel to the slit(s)?

lightconstant

please can someone answer my question?

jtbell

Yes, it happens the way I described it. I've seen it many times in undergraduate labs during the past 25+ years.

(not the single-photon-at-a-time version, but rather shining a laser beam through slits.)

lightconstant

Thank you jtbell