Novel laser level using a conical beam formation principle by a multimode fiber

Summary form only given. It has been known that an outgoing laser beam becomes a uniform ring beam having an angle of divergence, when a collimated laser beam is input with an angle to one fact of a multimode optical fiber. The angle of divergence of the laser beam outgoing from the optical fiber is decided by the angle of incidence of the laser beam. If the plane of incidence of the optical fiber is cut aslant and polished, a laser beam source can be disposed on the center axis thereof while maintaining the same effect. Then, a conical prism mirror having an apex angle adjusted to the angle of divergence of the outgoing beam of the optical fiber is disposed on the other side of the optical fiber. The conical laser beam reflected by the mirror becomes a thin and uniform flat beam having 360/spl deg/ of angle of divergence.