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Advanced measurement equipments

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Combinations of advanced measurement equipment

CRAL has four high-precision measurement equipments. This enables it to produce manufacturing, alignment, integration and test plans for the instrumentation of large telescopes; in particular for the HARMONI/ELT-ESO integral field unit and the 4MOST/VISTA-ESO low-resolution spectrographs. These four metrology tools can be combined together since they use the same Spatial Analyzer® data processing software.


  • Laser Tracker Hexagon

The Hexagon Leica Absolute Tracker AT403 allows measurement of large volumes up to 100 meters, with a minimum measurement distance of less than 0.8 meters for an accuracy of ± 15µm + 6µm / m. The Laser Tracker works either on a tripod or on magnetic bases. Several 7/8, 0.5 and 1.5 inches spherical mount reflectors (SMR) combined with a variety of mounts for circularity/centricity, flatness and angle measurements are available.

  • Metrology arm Hexagon

The Hexagon Absolute Arm 8520 enables opto-mechanical objects to be measured with an accuracy of ± 11.5 µm over a radius of 1000 mm. It includes a magnetic base and other supports that can be directly interfaced on an experimental bench. Different contact sensors are available with 15, 6 and 3mm balls including a touch trigger sensor and sensors with 45 and 60° angles with different lengths. A contact sensor for positioning a 0.5 inch reflector of the laser tracker system allows the coupling of a portable measuring arm and a laser tracker system.

  • 3D measuring machine TESA

The 3D measuring machine is a Tesa Micro Hite 3D with an accuracy level of ± 1.5 + 4L / 1000 μm (L in mm) for a measurement volume of 460 x 510 x 420 mm. It allows a quick and easy measurement of any common geometric element. Suitable for any user, easy to learn, it is the workshop instrument par excellence.

  • Photogrammétrie DPA Hexagon

The DPA (Digital Photogrammetric Assembly) is a digital photogrammetry system based on a Canon EOS 5DS - Zoom 35 mm portable digital camera that allows manufacturing controls to be carried out without the need to laboriously transport the parts to be measured to the measuring machine. It offers maximum flexibility in cramped or hard-to-reach areas. With a wide range of targets, adapters and standard bars, image capture and delivery of the measurement result take just a few minutes with AICON 3D Studio software. The measuring accuracy is 5 µm.

  • SpatialAnalyzer® (SA) software

SpatialAnalyzer® (SA) from New River Kinematics (NRK) is a portable metrology software solution for our instrumentation applications. SA is independent of the measuring instrument. Indeed, it is used with the four metrology tools listed previously at CRAL. It is a graphical 3D software platform that facilitates data analysis, adjustment, control with a CAD model, automation, reporting and reverse engineering on a wide variety of parts and tools.

Instruments de métrologie au CRAL

Study case from HEXAGON : Centre de Recherche Astrophysique de Lyon. The company HEXAGON came to CRAL for a case study. It is published here : ’Reaching for the Stars with Hexagon - Absolute Arm, Leica Absolute Tracker AT403, AICON DPA and TESA advanced measurement equipment as the key to unlocking the mysteries of the universe’.

Aknowledgements. The Absolute Arm, the Leica Absolute Tracker AT403, and the AICON DPA of HEXAGON were acquired with the financing support of the LabEx Lyon Institut of Origins (ANR-10-LABX-0066) of the University of Lyon. The 3D TESA was acquired on MUSE contracts.