Development of a two-step stylus with elastic hinge for microstructure measurement to improve sensitivity and vibration characteristics

In recent years, there has been an increasing demand for measuring a small hole with a diameter of 10 μm or less. Many micro coordinate measuring machines (micro CMMs) have been developed so far. However, as the diameters of these probes decrease below 10 μm, the rigidity of the probe decreases, making it difficult to detect contact between the stylus tip and the measured surface. For the same reason, the stylus with large aspect ratios cannot be used. Therefore, we have been developing a measurement system using an optical fiber as a stylus to measure microstructures with low measurement force. In this research, we proposed the two-step plus hinge stylus with a diameter less than a few μm to improve sensitivity and vibration characteristics. The design parameters of the stylus were simulated by the finite element method, and the results of the actual examination are summarized as follows. The simulation results using the finite element method indicate that the contact sensitivity was improved from 17% for the standard stylus to 37% for the two-step plus hinge stylus. The experimental results indicate that the contact sensitivity was improved from 17% for the standard stylus to 35% for the two-step plus hinge stylus. The results of the stylus stability evaluation experiment showed that the maximum fluctuation of the standard stylus is approximately 1 μm, and that of the two-step plus hinge stylus is approximately 0.05 μm, which confirms that the use of a two-step plus hinge stylus can improve vibration characteristics. The performance of this stylus was evaluated by measuring the micro hole with a diameter of 7 μm. The repeatability of each measurement point was approximately 50 nm.