An apparatus for the simultaneous detection of several ranges of wavelengths of polychromatic light radiation, using one detector for each detected range of wavelengths, includes an interference filter which filters the range of wavelengths to be detected out of the polychromatic light beam, and optical elements for guiding the polychromatic light beam to be detected. The optical elements include a first system of mirrors in the path of the incident polychromatic light beam for collimating it in a hollow-cylindrical manner, one mirror of the first system of mirrors being located at the center of the collimated light beam. The optical elements further include a second system of mirrors in the hollow-cylindrically collimated light beam that deflects this light essentially perpendicularly to the conceptual surface of the hollow cylinder and radially to the longitudinal axis of thereof. Photo-detectors associated with the particular deflection mirrors are mounted opposite the second system of mirrors to receive the deflected light. A common interference filter is mounted in the path of the beam between the deflecting mirrors and the photo-detectors, the deflecting mirrors and the associated photo-detectors being pivotable about the interference filter.