Mechanical design meeting, IAG, Calibration Unit mechanical design Svend M. Bauer Andreas Kelz, Emil Popow, Martin M. Roth

, IAG.2 CU Tech. Requirements for details see: ‚CU Technical Specifications‘, Version: 2.3 from: 26/04/2005 VLT-SPE-MUS CU to replace and mimic VLT beam - CU to provide all light sources for flatfield and spectral calibration - CU to provide masks for image quality and geometrical calibration - CU to select between calibration and science beam - CU to be used for Narrow and Wide Field Mode - CU to meet environmental requirements (e.g. stability, reliability, thermal emission, contamination, etc.) Pre-assumptions: - CU is placed outside the rotator unit, i.e. is stationary - VLT focal plane not accessible to CU - VLT focal and pupil plane to remain unchanged by GALACSI and FO

, IAG.3 Reminder: CU optical concept – A (large) integrating sphere for homogenous illumination (to simulate flatfield screen). – One calibration relay lens (CRL) to mimic VLT beam (using a telescope objective). -Precision masks at CU focal plane to calibrate instrument and to measure image quality.

, IAG.4 science beam calibration beam Integrating sphere Lamps & electronics inside cabinets Pick-up Element Calibration Relay Lens

, IAG.5 CU size & location CU size & location – CU beam to be injected between GALACSI and FO at 240 mm behind VLT focal plane. NEW ! – VLT focal plane not accessible to CU. – Overall length from CPE to CIS: 3 meters – folding mirrors (not shown) neeeded to accommodate CU. GALACSI ends: -500 VLT-focal plane: 0 CU-beam: +240 FO-starts: +320

, IAG.6 CU dimensions 1.3 m 1.6 m ca. 100 kg

, IAG.7 CU on platform: top view

, IAG.8 CU on platform: side view

, IAG.9 CU – outer parts Lamps and Proximity Electronic in individual housings Flexible Light Guides to connect lamps to CU (3 meters max.) Integrating Sphere for homogenous illumionation Stray light baffles Calibration optics to mimic telescope Folding mirror

, IAG.10 Calibration Mask Wheel on xyz-translation stage Folding Mirror common, aligned but removable platform VLT focus Calibration Pick-up Element on x-translation stage CU – inner parts

, IAG.11 Calibration masks MUSE pinhole mask: ~600 pinholes of 20 micron at 35x35 mm, MUSE trace mask: ~ 48 stripes of 0.123mm size precision and pitch tolerances: +/- 2 micron Laser-manufactured (LMTB) mask: 1024 pinholes of 12 microns each at 1x1 mm

, IAG.12  B3110 Calibration Unit mechanical design – No major risks identified with mechanical design – Cost of Integrating Sphere: 10 kEuros – Cost of Precision Masks: 1 kEuro/piece – Location of CU depending on final FO-platform – CU estimated weight around 100 kg – Removability of CU for GALACSI dismounting addressed CU: Summary