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Diffraction at a blazed grating. The general case is shown with red rays; the Littrow configuration is shown with blue rays. The Littrow configuration is a special geometry in which the blaze angle is chosen such that diffraction angle and incidence angle are identical. [1]
A blazed diffraction grating reflecting only the green portion of the spectrum from a room's fluorescent lighting. For a diffraction grating, the relationship between the grating spacing (i.e., the distance between adjacent grating grooves or slits), the angle of the wave (light) incidence to the grating, and the diffracted wave from the grating is known as the grating equation.
The sine and tangent small-angle approximations are used in relation to the double-slit experiment or a diffraction grating to develop simplified equations like the following, where y is the distance of a fringe from the center of maximum light intensity, m is the order of the fringe, D is the distance between the slits and projection screen ...
The Greninger chart is a simple trigonometric tool to determine g and d for a fixed sample-to-film distance. (If one uses a 2-d detector the problem of determining g and d could be solved mathematically using the equations which generate the Greninger chart) A new chart must be generated for different sample to detector distances.
Visulization of flux through differential area and solid angle. As always n ^ {\displaystyle \mathbf {\hat {n}} \,\!} is the unit normal to the incident surface A, d A = n ^ d A {\displaystyle \mathrm {d} \mathbf {A} =\mathbf {\hat {n}} \mathrm {d} A\,\!} , and e ^ ∠ {\displaystyle \mathbf {\hat {e}} _{\angle }\,\!} is a unit vector in the ...
The free spectral range of a diffraction grating is the largest wavelength range for a given order that does not overlap the same range in an adjacent order. If the ( m + 1)-th order of λ {\displaystyle \lambda } and m -th order of ( λ + Δ λ ) {\displaystyle (\lambda +\Delta \lambda )} lie at the same angle, then
which is the generalized diffraction grating equation. Here, θ m is the angle of incidence, φ m is the angle of diffraction, λ is the wavelength, and m = 0, 1, 2... is the order of diffraction. Under certain conditions, d m ≪ λ, which can be readily obtained experimentally, the phase term becomes [7] [10]
An echelle grating (from French échelle, meaning "ladder") is a type of diffraction grating characterised by a relatively low groove density, but a groove shape which is optimized for use at high incidence angles and therefore in high diffraction orders. Higher diffraction orders allow for increased dispersion (spacing) of spectral features at ...