Diffraction Grating Calculator

Background

A diffraction grating is a material that contains a large number of parallel slits separated by a distance (d). This periodic separation of slits is usually on the order of micrometers. Because this distance is on the order of the wavelength of light, when light waves pass through the grating the slits are able to cause constructive and destructive interference among the light waves. The waves will constructively interfere if the angle of reflection delays one of the waves by a whole wavelength:

The calculator below will accept as input parameters the wavelength of the incident light, the grating spacing, the angle of incident light, and the distance from the grating to the screen. It will output the various modes where constructive interference will cause a light band to appear if the light is in the visible spectrum. The format of the output is m="mode number", angle of reflection, and distance from the centerline of the screen to where the mode will be centered.

Parameters
Wavelength (lamba):	(nm)
Grating spacing (d):	(um)
Angle of incidence (thetaI):	(°)
Distance from grating to screen (D):	(cm)
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