PaschenRunge

The Paschen-Runge spectrometer is a type of optical instrument used for analyzing the spectral properties of light, particularly in the ultraviolet (UV) and visible regions of the electromagnetic spectrum. Developed by Friedrich Paschen and Albert F. H. Runge in the late 19th century, it is a variant of the normal incidence spectrometer, which employs concave diffraction gratings to disperse light into its constituent wavelengths.

The primary advantage of the Paschen-Runge design is its ability to achieve high resolution and efficiency in the UV region, where traditional prism spectrometers often struggle due to material absorption and dispersion limitations. Unlike the Littrow configuration, which uses a single mirror to reflect light back through the grating, the Paschen-Runge spectrometer employs a series of curved mirrors to direct the dispersed light onto a stationary exit slit. This arrangement allows for a more compact and versatile setup while maintaining high spectral purity.

The instrument consists of a concave diffraction grating, an entrance slit, a series of spherical mirrors, and a movable exit slit or detector. Light entering through the slit is dispersed by the grating, and the mirrors reflect the different wavelengths to the exit slit, where they can be analyzed. The Paschen-Runge design is particularly useful in applications such as atomic spectroscopy, where precise measurements of emission or absorption lines are required.

Over time, advancements in materials and optical engineering have led to modern variations of the Paschen-Runge spectrometer, often incorporating holographic gratings and digital detection systems. Despite its age, the fundamental principle of the Paschen-Runge design remains influential in both historical and contemporary spectroscopic research.