The present invention has been directed to a light path for an optical system for measuring an optical path including the receiving light emitted receiving end from the transmitting end and the transmitting end for emitting light generated from the light detection device, between the transmitter and the receiver exit doedoe this stage detection optical path for detecting the optical arrangement, it provided that the detection light path is provided with a transparent film on at least one side, wherein the predetermined fluorescent material or phosphorescent material that is photosensitive member is applied to the surface of the transparent film; Through a connection member connected with the lower surface of the optical sensing member is connected to the photosensitive member, the vibrating member for vibrating the optical sensing member; And is disposed in contact with the lower surface of the vibrating member, the support member for supporting said photosensitive member and said vibrating member; And it characterized in that it comprises a.
With this configuration, by placing this optical system optical path in the sensing device of the present invention, the optical system light sensing member between an optical transmitter and the receiver to emit a predetermined surface of a transparent film provided on one surface of the photosensitive member for applying a fluorescent material or a phosphorescent material, by rotating or vibrating the optical sensing member, wherein the photosensitive member is effective to check the path of light traveling within the optical system with the naked eye.