Angular spread in diffraction grating

[profbored]

hi,
i have a question here tt i hope some kind souls out there can clarify with me.
if i shine a monochromatic light, let's say 500 nm, at a diffraction grating, will i onli get spectral lines, or will there be some orders which give me an angular spread? cos when u draw the graph of intensity against sin(theta) for a monochromatic diffraction grating, u get a detectable spread for each peak.

 

[Doc Al]

The intensity pattern of a diffraction grating shows a set of bright lines (at the primary maxima) which get brighter and narrower as the number of slits in the grating increase. Of course there is an angular spread, but for all practical purposes the sharp peaks are "lines".

This may help: http://230nsc1.phy-astr.gsu.edu/hbase/phyopt/gratint.html#c1