Determine the slit-with and slit-distance of a double slit laser diffraction

[Firben]

Parallel laser light with wavelength 633 nm are incident perpendicular against a double slit. 2.50 m behind the double slit is a screen where the pattern can be seen (link below). Determine with the help of the figure the slit-with and slit-distance.

http://s716.photobucket.com/albums/ww168/Pitoraq/?action=view&current=DSC_01821.jpg

Formulas:

Slitwith:

b = slithwith

bSin(v) = λ*m

where Sin(v) ~ v = y/L

b = (λ*L)/(y(diffmin))

Slit-distance:

d = (λ*L)/(y(max))

d = distance
How can i get y(diffmin) and y(max) out of the figure ?(ignore my measurment in the figure) The answer should be b = 0.099 mm and d = 0.30 mm

 

[TSny]

Hi Firben. The figure shows the combined effect of double slit interference and single slit diffraction. Can you tell us from the figure the locations of the two first-order single-slit diffraction minima and the locations of the two first-order double-slit interference maxima?

This might help: http://en.wikipedia.org/wiki/File:Single_slit_and_double_slit4.jpg