Optical system for spectrometers

An optical system comprising:

• at least one entrance aperture for entering light to be analyzed,
• at least one diffraction grating for spectral dispersion of the light,
• at least two detectors to measure a spectrum of the light, where the detectors are arranged on a same side of a plane of dispersion of the optical system, and
• at least two vertically focusing mirror elements for focusing the light onto said detectors assigned to said vertically focusing mirror elements, characterized in that
• the vertically focusing mirror elements are arranged as front row mirror elements and back row mirror elements along two polygon graphs offset to each other and to a focal curve, where each section of the polygon graph is parallel to its dedicated local tangent to the focal curve of the grating, such that
• angles of deflection for the front row mirror elements are <90° allowing to minimize the offset of the front row mirror elements to the focal curve,
• distances between said front row mirror elements and corresponding detectors assigned to said front row mirror elements is minimized while still avoiding collisions between the corresponding detectors and their mounts with back row detectors and their mounts, and
• at least one end of said front row mirror element is overlapping adjacent back row mirror element or a receptive area of an adjacent direct light detector if regarded from the grating.