Shape measurement based on fiber-optic technique for complex internal surface

Reverse engineering based on fiber-optic technique is a very new topic in C AD/CAM fields. A novel single-mode fiber-optic sensor is presented based on the principle of beam reflection to implement the digitizing of complex su rface shape. The fibers in the sensor probe are arranged like a spoke with eight symmetrically cross-arranged receiving fibers and one centered emitti ng fiber. Thus, the sensor can compensate for the offsets caused by fluctua tions of surface reflectivity and light power and is fit for application un der rough and formidable conditions with noncontact, fast shape measurement . A prototype was developed based on the simulation results to verify the f easibility. With the GRIN lens on the exit end of the single-mode emitting fiber, the lateral resolution was greatly improved compared with former mul timode fiber-optic displacement sensors. Preliminary experiments indicated that the estimated uncertainty of displacement measurement was better than +/-2 mum, and the uncertainty of +/-5.6 mum can be obtained when measuring a MJ20 X 1.5 thread. (C) 2001 Elsevier Science Ltd. All rights reserved.