Diffraction Grating

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Diffraction gratings are surfaces with regular, very small reflective features, which cause light to be diffracted through interference.

The most common diffraction grating we see every day is a CD-R, which, because of its regular tracks, splits daylight into its component fractions spatially.


All gratings diffract light in different orders. Zero-order diffraction is the light which is essentially just reflected or transmitted with no change. First-order diffraction is the light which is actually split, and it will in general have include a conjugate first-order, light which is split on the other side of the grating. Gratings are generally built to minimize both zero-order and conjugate-order diffraction, the first because there is no separation, the second because it decreases the light intensity by creating two or more spectra in different directions.

Transmission or amplitude gratings are gratings which are transparent, hopefully to all spectra. Light separates as it goes through them.

Diffraction or blazed gratings refer to gratings which are reflective.

The blaze angle and the number of features/mm are important quantities in order to find the actual ordered diffraction of the specific grating, which will generally need to be optimized for the particular spectra and intensity of light.

It is not clear how to relate these quantities just yet. Before ordering parts, have ordered optics books to discover.

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