A self - mixing laser sensor for the real - time correction of straightness/flatness deviations of a linear slide

摘要

The development of a contactless sensor based on the Laser-Self-Mixing effect for the simultaneous measurement of linear and transverse degrees-of-freedom (DOFs) of a moving target is described in this paper. The sensor is made of three laser diodes with integrated monitor photodiodes, and a properly designed reflective target attached to the moving object. The proposed technique exploits the differential measurement of linear displacements by two identical self-mixing interferometers (SMIs) and makes the system more compact and easier to align with respect to traditional interferometric systems, thus providing an effective low-cost motion control system. The feasibility of the proposed sensor is experimentally demonstrated over a range of 1 m for linear motion and ± 6 mm for transverse displacements, with resolutions of 0.7 μm and 20 μm, respectively.