Development of a low-cost nanoscale touch trigger probe based on two commercial DVD pick-up heads

This study develops a low-cost three-dimensional nanoscale touch trigger probe based on two commercially available DVD optical pick-up heads. The probe is attached to a cross-form structure suspended from a symmetrical arrangement of thin steel strips. The displacements of the probe tip in response to a contact force are initially investigated using a theoretical approach and are then confirmed using ANSYS finite element software. A touch trigger probe system is then constructed in accordance with the finite element simulation results, and a series of experimental investigations is performed to evaluate its performance characteristics. In general, the results show that the symmetrical suspension mechanism restricts the probe to three degrees of motional freedom, achieves an equal stiffness condition in every direction and reduces the pre-travel error. It is shown that the touch trigger probe has a pre-travel variation of less than 96 nm in all measurement directions and a unidirectional repeatability of 46 nm. Finally, the maximum triggering force is found to be less than 0.1 mN for any approach angle.