Diffraction Grating

This is a very useful aperture which consists of a great many parallel, evenly spaced slits. The resulting diffraction pattern is characterized by principle maxima located by

d sin(q) = ml

where d is the slit spacing and m is the order number. The resolving power of the grating is given by

R = Nm

where N is the number of slits illuminated and m is the diffraction order.