NOVELTY - The lamp (1) has illumination optical fibers (2) i.e. 7165 glass fibers, whose outlet ends (2.2) are arranged in form of a ring (9) and inlet ends (2.1) are combined to form an inlet bundle (4) exhibiting a rectangular cross-section. Inlet ends (3.1) of reference optical fibers (3) are arranged in the inlet bundle. Outlet ends (3.2) of the reference optical fibers are combined to form a reference outlet bundle (7) apart of formation of the ring. The outlet ends of the illumination optical fibers are packed in a sealed manner. A cylindrical lens is designed as a rotation body for the lamp.    USE - Ring lamp i.e. split ring lamp, for use in a measuring head of a compact optical spectrometer system (all claimed) such as wide range spectrometer system i.e. dual ray-wide range spectrometer system, for detection of rays that are re-emitted from a measuring surface, for recognizing and/or classification of materials by measuring optical material characteristics and for illumination purpose in microscopy, ophthalmology, photography, optical spectroscopy, agricultural field, foodstuff industry and during recycling of residual material and production of solar cells.    ADVANTAGE - The inlet ends of the reference optical fibers are arranged in the inlet bundle, and the outlet ends of the reference optical fibers are combined to form the reference outlet bundle apart of formation of the ring, thus accurately receiving reference rays at reduced expenditure, with increased efficiency and without the use of additional auxiliary units such as reflectors and divider plate, and achieving robust internal referencing of illumination light. The lamp can be utilized for the optical spectrometer system with reduced complexity.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a spectrometer system comprising a unit for optical homogenization of light.    DESCRIPTION OF DRAWING(S) - The drawing shows a pseudo-perspective view of a ring lamp with a reference junction.    Ring lamp (1)    Illumination optical fibers (2)    Inlet ends (2.1, 3.1)    Outlet ends (2.2, 3.2)    Reference optical fibers (3)    Inlet bundle (4)    Outlet bundle (7)    Ring (9)