Fiber optic surface topography measurement sensor and its design study

This paper presents some aspects of design approach, modeling, and experimental measurement results of a fiber optic-based surface topography measurement sensor that can measure surface roughness as well as the distance between the sensor tip and a surface and surface inclination angles. The working principle of the sensor is based on the detection of light intensity reflecting from the surface being measured. The sensor is very small and easy to operate. It can be attached to a coordinate measuring machine (CMM) to measure surface position coordinates, inclination angles, and surface roughness in a noncontact manner at one measurement setup. A theoretical model of intensity distribution and intensity detection has been established for the sensor. A three-factor and three-level experiment was designed to investigate the relationship between sensor performance and sensor design parameters. Two second-order regression models have been generated, which show that the central distance between the emitting and receiving fibers of a sensor has the strongest influence on the effective range of the sensor; whereas, the critical angle of a receiving fiber influences the sensitivity of the sensor most.