Laser interference 3-D sensor with line-shaped beam based multipoint measurements using cylindrical lens

Laser Doppler distance sensors enable an absolute shape measurement of rotating objects for instance for monitoring the turning process of workpieces by a simultaneous velocity and distance measurement. However, the sensors allow only single-point measurement, which makes a 3-D measurement time-consuming and limits the sensor application. Therefore, this article presents a novel sensor setup for simultaneous multipoint measurements. Cylindrical lenses are employed to produce expanded, line-shaped laser beams and thereby increase the number of measuring points in a single measurement. A line camera based detection method is proposed for high-speed full field detection, lateral resolution increase and measurement uncertainty reduction. As a result, the proposed sensor system enables simultaneous velocity, distance and thus 3-D absolute shape measurements at a rotating object, with a simultaneous measurement of up to 480 points and a total measurement uncertainty below 1 μm. Moreover, the lateral resolution can be increased by the order of one magnitude to 4.2 μm.