A hybrid sensor for the measurement of a wide range of longitudinal surface displacement based on laser reflection and scattering

A hybrid sensor for measuring longitudinal surface displacement including surface undulation and surface roughness over a wide range from nm to a few hundred mu m has been developed. Two main sensors are incorporated in a single body, i.e., it is a hybrid system, with one sensor based on laser reflection for nm-scale measurement, while the other is based on imaging the irradiated portion for mu m-scale measurement. A preliminary experiment using this hybrid sensor showed that the sensor for measuring surface undulation has a longitudinal resolution of 1 nm and a measurement frequency of 24 Hz, and that the sensor for measuring surface roughness has a longitudinal resolution of 2 mu m, a measurement range of +/- 300 mu m and a measurement frequency of a few hundred Hz. This hybrid sensor is relatively compact and its cost/performance ratio allows its practical use.