Structure Design of A Laser Confocal Probe For Measuring the Micro-Sphere

To achieve the aim of precise position measurement of a target micro-sphere, approximately 0.2mm in diameter, a laser confocal probe, on an active focus adjusting principle, was introduced in this paper. For finding the effect way to improve the output signal, a mathematical modal of the photoelectric signal was proposed. Based on the mathematical modal, the diameter of the pinhole was decided and the optical path was adjusted, which forward the performance of the probe. The tuning fork stimulating, inductive coils and the pinhole adjuster device were designed according to the theoretical analysis, which were more convenient to the measure task. The stability of the intact oscillating unit was tested; and the optical and mechanical performance of the probe was validated by experiments using gage blocks combining with a calibrated micro-driven table. Besides, a more accurate signal processing method was suggested in this paper.