Stages for the SSW translation system for PACMAN Accuracy verification of the CERN metrology lab

Introduction Accurate translation stages required for Stretched Wire magnetic measurement systems 2 XY mounts on granite directly ordered from company (PImiCos, DE) At delivery accuracy verification performed on the Leitz Infinity 3D measuring machine

Stages specifications Property Value Travel Range (horizontal/vertical) 50 mm Encoder Type Linear Repeatability of displacement ≤ 0.05µm Bidirectional repeatability ≤ 0.1 µm Min. incremental motion ≤ 0.05 µm Accuracy over 50 mm < 1 µm Origin repeatability < 0.05 µm Pitch/Yaw +/- 15 µrad Orthogonality of the XZ stages < 15 µrad Straightness/Flatness +/- 0.5 µm

Setup at the CERN metrology lab 5 kg load Probe fixed at 50 mm from the surface of the table Coordinate system plane YZ defined according the maximum stroke positions

Absolute accuracy tolerance Measurement performed at 50 mm from the table surface: Absolute XY position allowed error (RMS): Accuracy 1 um Pitch/yaw 0.75 Orthogonality Straightness/Flatness 0.5 Total 1.5 Leitz absolute error 0.35 Total maximum allowed error ±1.9

Main absolute measurement positions

Results over full stroke (50 mm)

Range used in PACMAN - Real displacement range during PACMAN use: ± 3 mm in vertical and horizontal from centre - Re-measurement of the critical area on the Leitz machine

Conclusion - Stages out of specification: Absolute positionning errors on full 50 mm stroke still up to 2.8 um (max. admissible error ±1.9 um) Straightness/flatness (X and Y enveloppe) of V-axis = 1.3 um (max. spec. ±0.5 um) Orthogonality stage B = 0.039 urad (specified ≤ 15 urad) No time for sending the stages back to manufacturer ±10 mm limited measuring area for use with PACMAN within tolerance (±1.9 um) Less criticial for axis finding with the vibrating wire method with best fit Alternative solution: send back the stages and use SSW5 stages instead but need of checking overall dimensions for integration on the Leitz PACMAN setup