Abstract: A mechanical optical switching device has a plurality of input optical fibers coupled to the input side of the mechanical switching device for receiving incoming light beam signals. Individually associated with each optical fiber is an input collimating lens which is positioned to receive the incoming light beam and to convert it into parallel light beams. Optical path-switching means, having a uniform refractive index, are disposed at the rear or output of the input lens for switching the optical paths of the collimated parallel light beams emerging from the input lens means. A plurality of output optical fibers have individually associated output lenses for focusing the parallel light beams, after they have passed through the position controlled by the optical path-switching means.