Novel design of a one-dimensional measurement probe

The mechanical probing system is often one of the limiting factors in the calibration of length standards. It has been shown, that for highly accurate applications a particular effect, which is often not considered, has to be taken into account: A spherical probe on a stylus undergoes a small rotation due to the angular stylus deflection, which creates friction and potentially stick slip during the probing process and may thus lead to non-reproducible probing. A novel probe has been built which avoids this effect by an additional degree of freedom, providing a small vertical movement of the stylus. The probe is of a monolithic flexure hinge design with a rigid connection of the stylus and the mirror reflector for the plane mirror interferometer, which measures the displacement. The measurement force, which is proportional to the deflection of the hinges, is measured with a capacitive probe. The probing procedure generates the force/deflection curve and allows for the measurement force to be extrapolated to zero. The presented test results show the system's capability for a probing accuracy in the nanometer range.