Knowra Diffraction grating Diffraction grating A diffraction grating is an optical element with a periodic structure that redirects light into discrete directions. The angles depend on wavelength, allowing the grating to separate light by color.
Grating equation : An equation relating grating spacing, incidence and diffraction angles, wavelength, and diffraction order. It predicts where each wavelength emerges from a grating.
Wavelength : The spatial period of a wave, measured between successive points with the same phase. A grating sends different wavelengths into different angles.
Diffraction grating spectrometer : A spectrometer that separates light by wavelength using a diffraction grating. It turns the grating’s angular separation into a measurable spectrum.
Prism : A transparent optical element that redirects light through refraction, often dispersing wavelengths by color. A prism disperses light by refractive index rather than periodic diffraction.
Diffraction : The spreading and redirection of waves when they encounter an aperture, obstacle, or periodic structure. A grating produces its directional beams through interference among diffracted waves.
Spatial frequency : The number of repeating cycles of a pattern per unit distance. A grating’s spatial frequency is the reciprocal of its period and sets angular dispersion.
Echelle grating : A coarse-pitch, steeply blazed grating used at high diffraction orders for high-resolution spectroscopy. Its high orders support fine spectral separation in compact instruments.
Holographic grating : A grating formed by recording an interference pattern, typically producing smooth, sinusoidal grooves. Its groove profile differs from mechanically ruled gratings and can reduce stray light.
Interference : The combination of waves that produces reinforcement or cancellation according to their relative phase. Constructive interference selects the directions of the grating’s bright orders.
Coherence length : The distance over which a wave maintains a predictable phase relationship with itself. Coherence affects how sharply light from many grating periods forms interference maxima.
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