Is Bragg Diffraction Depicted Accurately in Common Diagrams?

[2sin54]

Hi. So I am studying a bit on acousto-optics and as far as I've gathered, when the Bragg condition is met, the incident ray of light should just be reflected (in a perfect case) with the angle of reflection equal to the angle of incidence.
However, this picture does not agree with my thoughts: http://www.mt-berlin.com/pict_0/fig1ao.gif

Is it correct? I mean the Bragg diffraction. The picture clearly suggests that the incidence and reflection angles need not be equal..

 

[sophiecentaur]

Hi. So I am studying a bit on acousto-optics and as far as I've gathered, when the Bragg condition is met, the incident ray of light should just be reflected (in a perfect case) with the angle of reflection equal to the angle of incidence.
However, this picture does not agree with my thoughts: http://www.mt-berlin.com/pict_0/fig1ao.gif

Is it correct? I mean the Bragg diffraction. The picture clearly suggests that the incidence and reflection angles need not be equal..

If they were always equal, I think that X Ray crystallography would not work. All that's necessary is for the Bragg criterion to be satisfied.

 

[2sin54]

If they were always equal, I think that X Ray crystallography would not work. All that's necessary is for the Bragg criterion to be satisfied.

Hmm, but there's plenty of pictures like these: http://skuld.bmsc.washington.edu/~merritt/bc530/bragg/index_files/BraggDeriv.gif . They seem to suggest that the angles are in fact equal. I am really confused right now.

 

[sophiecentaur]

Can you not get different orders for the incoming and outgoing beam? Perhaps not. The Bragg equation doesn't suggest that you can.
The most likely answer is that the diagram you are looking at is just drawn wrong.