Diffraction pattern due to a lens with focal length f

[Optik123]

Summary:

The question is how distances between lines behave after a lens.

Suppose one light up with a laser on a grid with grid constant g. The grating is followed by a focusing lens with a focal length of f. In the focus (or immediately in front of it) the maxima have a distance d. How large was the distance of the maxima immediately after the grating?

scheme:
Laser beam----------grating=======Lens=======focal point(here the maxima have distance d from each other)

Note:
The angle of the k.th maximum is given by

Best wishes and many thanks!

 

[berkeman]

Welcome to the PF.

Can you show your work on this problem? Is this a schoolwork problem?

 

[sophiecentaur]

@Optik123 The width of the laser beam will affect how much of the grid is illuminated, which will affect the diffraction pattern. It's like a Windowing Function being applied. Are you sure that the problem you have is expected to be as complicated as this? Is the mention of 'laser' just to imply a good coherent source?