Grating Intensity Comparison

The grating intensity expression gives a peak intensity which is proportional to the square of the number of slits illuminated. Increasing the number of slits not only makes the diffraction maximum sharper, but also much more intense. If a mm diameter laser beam strikes a line/mm grating, then it covers slits and the resulting line intensity is x that of a double slit.

Multiple slit diffraction

Index

Diffraction concepts

Fraunhofer diffraction

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Grating Intensity

The two aspects of the grating intensity relationship can be illustrated by the diffraction from five slits. The intensity is given by the interference intensity expression

modulated by the single slit diffraction envelope for the slits which make up the grating:

This gives a total intensity expression:

Multiple slit diffraction

Index

Diffraction concepts

Grating concepts

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