Rotary mount design for a chromatic confocal sensor, involving additive manufacturing and an opened air bearing

In the field of high energy physics, the characterisation and positioning in space of a wire with a diameter of 0.1 mm is one of the steps to increase the precision of future accelerators’ pre-alignment. This reference wire is measured within a high accuracy Coordinate Measuring Machine (CMM) to reduce its positioning uncertainty. No sensor could measure the wire position within the targeted uncertainty. This thesis addresses this issue by proposing a design for the Shape Evaluating Sensor: High Accuracy & Touchless (SESHAT). The SESHAT operates a chromatic confocal sensor. The sensor is fixed to a rotor with a radial opening to allow the stretched wire to traverse it. This rotor is guided by a high precision air bearing controlled by a piezoelectric actuator. The mass limit for the stylus system of the CMM entailed the additive manufacturing of a hollow rotor. The high likelihood of particles on the wire surface involved a form deviation capability for the SESHAT, to reduce position measurement uncertainty. The aim of the research was to design a sensor enabling the Leitz Infinity CMM to perform non-contact form measurement on the PACMAN reference wire to permit its axis positioning with an uncertainty such that 3σ < 0.5 µm. The novelty emphasised in this thesis is focused on three main contributions. The form measurement uncertainty reduction obtained by using a chromatic confocal sensor for non-contact measurement on a wire surface is the first contribution. A mathematical model describing the behaviour of air pads over a through hole in the bearing surface composes the second contribution to knowledge. The demonstrated ability to obtain a micrometric form deviation on a rotary symmetric complex shape generated by additive manufacturing of titanium is the third contribution