WORKPIECE POSITION SENSING BY MEANS OF A FIBER OPTICAL BEAM DELIVERY SYSTEM

We report a method of measuring workpiece position in laser material processing and machining that uses a fiber optical beam delivery system. The method is based on a measurement of the power propagating in the cladding of the optical fiber in the direction from the workpiece to the laser. The power reflected from the workpiece and coupled into the cladding is shown to be a function of the position of the workpiece relative to the beam waist formed by the output optics of the beam delivery system.