spektrograph

A spektrograph is an optical instrument used to record the spectrum of light from a source by dispersing the light into its component wavelengths and imaging the result onto a detector. The basic principle involves guiding light through an entrance slit, collimating it, and then exposing it to a dispersive element such as a diffraction grating or a prism. The dispersed light is then focused by a camera optic onto a detector, which records a spectrum that can be analyzed to determine the light’s properties.

Common implementations include grating spektrographs, which use diffraction gratings to achieve high dispersion, and prism spektrographs, which rely on refractive dispersion. More specialized designs, such as echelle spektrographs, employ high-dispersion gratings arranged in a cross-dispersed configuration to cover broad wavelength ranges with high resolution. Fourier-transform spektrographs use interferometry to measure spectra and are widely used in laboratory settings for high precision.

Key performance characteristics are spectral range, spectral resolution (often described by the resolving power, R = lambda/delta lambda), sensitivity, and throughput. The choice of slit width, optical design, and detector type (such as CCDs or photomultiplier tubes) influence these parameters.

Applications span astronomy, where spectra reveal chemical composition, temperatures, densities, and radial velocities; chemistry and materials science, for qualitative and quantitative analysis; and environmental sensing and industrial quality control. The instrument has a long history in spectroscopy, evolving from early glass-prism devices to modern high-resolution, electronically coupled detectors.