Abstract: A corner reflector (e.g. a periscope) is made of a prism block having a viewing-in end and a viewing-out end with mirrored inclined surfaces or deflection mirrors applied on its inclined surfaces and also functional plates arranged in front of the viewing-in end and/or the viewing-out end. In the corner reflector, as far as possible, no signs of detachment of the deflection mirrors arranged thereon or of functional plates occur and which has an increased lifetime, which is achieved by all plate-shaped components, such as the deflection mirrors and the functional plates. All solid components of the corner reflector, such as the prism block, are made of plastic.