Reflection Grating -- from Eric Weisstein's World of Physics

Optics "> Gratings v

Optics "> Reflection v

Reflection Grating

The behavior of a reflection grating can be analyzed by solving the following four equations in four unknowns,

where i and are not necessarily equal (for example, the angles are not equal in a so-called blazed grating). i and are usually chosen so that

Then

and the path length difference between the two paths is

Angular Dispersion, Grating, Grating Equation