A waveguide for a detector system includes a transparent main body with a partially transparent incoupling region and a decoupling region that is spaced apart therefrom in a first direction. The incoupling region includes a diffractive structure which deflects only part of radiation coming from an object to be detected and impinging on the front face such that the deflected part propagates as coupled-in radiation in the main body by reflections up to the decoupling region and impinges on the decoupling region. The decoupling region deflects at least part of the coupled-in radiation impinging thereon such that the deflected part exits the main body via the front face or rear face in order to impinge on the detector system. The extent of the incoupling region in a second direction transverse to the first direction is greater than the extent of the decoupling region in the second direction.