Integral Field Spectrograph Optomechanical concepts PIERRE KARST JEANLUC

Integral Field Spectrograph Opto-mechanical concepts PIERRE KARST, JEAN-LUC GIMENEZ CPPM(CNRS), FRANCE November 15 & 16, 2005 Pierre KARST

Summary Ø Requirements Ø General design Ø Opto-mechanical mount principle Ø References definition Ø Description of the units Ø Optical baffling studies Ø Cold test : preliminary lay out Ø Conclusion November 15 & 16, 2005 Pierre KARST 2

Requirements 1/2 • Optical scheme : Beam geometry and active surfaces of the optical components • • = 350 to 1700 nm : Visible and IR detectors Respect of the alignment tolerance from 300 to 100 K Adjustment of the optical components and the detectors Optical components made of Zerodur (mirror) and BK 7 (prism) November 15 & 16, 2005 Pierre KARST 3

Requirements 2/2 • Alignment tolerance Detector unit Steering mirror unit Spectrograph unit GENERAL REQUIREMENT: COMPONENT X = Y= Z= ± 0, 1 mm Slicer unit X = Y= Z= ± 0. 02 mm Bench November 15 & 16, 2005 Tilt Ox= Oy = ± 5 arcmin UNIT X = Y= Z= ± 0, 2 mm Offner relay unit Tilt Ox= Oy = Oz = ± 5 arcmin Pierre KARST 4

General design 1/5 Overview Spectrograph unit Detector unit Bench Support of the units Steering mirror unit Offner relay unit Slicer unit Interface with external devices November 15 & 16, 2005 Pierre KARST 5

General design 2/5 • Overall dimensions with the IR detector 420 mm 210 mm 630 mm November 15 & 16, 2005 Pierre KARST 6

General design 3/5 Slicer and spectrograph region (# SNAP spectro) 95 mm 160 mm November 15 & 16, 2005 270 mm Pierre KARST 7

General design 4/5 • Visible test at room temperature Illumination module of the Proto 0 Demonstrator Optical table November 15 & 16, 2005 Support Pierre KARST 8

General design 5/5 Choice material trade off: Compatibility with vaccum at low temperature (100 K) compatibility with Zerodur (Low CTE) Good alignment in the temperature range (300 -100 K) Good thermal properties high Young modulus Short allowed time = easy fabrication Low cost Invar Aluminium Titanium Zerodur Si. C CTE (300 -100 K)x 106 1. 6 19 8 0. 05 1. 3 Thermal cond @ 300 K (W/m/K) 13 237 22 1. 6 190 Specific heat (J/Kg/K) 500 900 523 821 700 Young modulus (GPa) 150 71 114 91 420 Cost A A A B C Fabrication A A A B C November 15 & 16, 2005 Pierre KARST 9

Opto-mechanical mount principle 1/6 Optical components : Rectangular mirror, Zerodur, 110 x 30 x 20 Cylindrical mirror, Zerodur, 26 to 34 x 10 Prism, BK 7, mean thickness 10 mm, 26 x 26 Mount components : Frame and positioning parts, Invar. Clamping and screws : TBD Requirement in the range 300 to 100 K : Positioning tolerance : ± 0. 1 mm ± 5 arcmin November 15 & 16, 2005 Pierre KARST 10

Opto-mechanical mount principle 2/6 • Cylindrical mirrors : Elastic clamping Plan contact with 3 points Mirror mount Mirror Centering with 2 small machined plans Support November 15 & 16, 2005 Pierre KARST 11

Opto-mechanical mount principle 3/6 Rectangular mirror: Plan contact Spring plungers Punctual contact Orientation Elastic clamps Mirror November 15 & 16, 2005 Pierre KARST 12

Opto-mechanical mount principle 4/6 • Mirror mount positioning: Spring plungers for the alignment Screws for fixation Stopper November 15 & 16, 2005 Pierre KARST 13

Opto-mechanical mount principle 5/6 • Prism mount: 6 elastic clamps Prism November 15 & 16, 2005 3 rotations are required. Positioning by 3 axis and screws on cantilever. 6 small pads Pierre KARST 14

Opto-mechanical mount principle 6/6 • Prism mount: Position adjustment Y adjustment Z adjustment Centering of the axis < 10 mm Accuracy of the angular adjustment < 3 arcmin Y Z Spring plunger X adjustment X November 15 & 16, 2005 mm screw Pierre KARST 15

References definition 1/2 General reference: Active surface positions Y Z Z Y Y O Z Y Origin = Slicer reference November 15 & 16, 2005 Pierre KARST 16

References definition 2/2 Active surface Positioning and measurement of the actives surfaces respecting to the Unit reference Supporting surfaces of the mount External surfaces Unit reference Positioning surfaces of the mirror Accuracy of reference transfer with a CMM < 10 mm èPositioning of the active surface < 40 mm (Alignment tolerance = ± 0. 1 mm) November 15 & 16, 2005 Pierre KARST 17

Description of the units 1/8 Travel along the beam Detector unit Spectrograph unit Offner relay unit Slicer unit November 15 & 16, 2005 Pierre KARST Bench Steering mirror unit 18

Description of the units 2/8 Steering mirror support unit Steering mirror envelop Titanium support Outgoing beam X Incoming beam Pupil aperture Z Y Contact plan Locating hole Centering hole November 15 & 16, 2005 Pierre KARST Shrinkage around the vertex of the mirror 19

Description of the units 3/8 Incoming beam Slicer unit Pupil mirrors Stack of slices Outgoing beam Slit mirrors X Z November 15 & 16, 2005 Pierre KARST Y 20

Description of the units 4/8 Slicer unit Slice mirrors support Box and cover Mirror supporting blocks Made of Invar Made of Zerodur Mirror supporting blocks Pupil and slit mirror support Made of Zerodur The Zerodur assembly will be held by elastic clamps (TBD) November 15 & 16, 2005 Pierre KARST 21

Description of the units 5/8 Spectrograph unit Outgoing beam Camera mirror Collimator mirror Prism Incoming beam Stopper Orientation X Y Z Plan contact November 15 & 16, 2005 Pierre KARST 22

Description of the units 6/8 Offner relay unit Offner primary mirror Plane mirror Detector focal plan Stopper Orientation X Z Y Offner secondary mirror Incoming beam Plan contact November 15 & 16, 2005 Pierre KARST 23

Description of the units 7/8 Visible detector Fixation X Y Z Contact plan November 15 & 16, 2005 Pierre KARST 24

Description of the units 8/8 Bench • • • Support of the unit Connection to the external devices Keeps the alignment specification (stiffness and thermal fluctuation) Stopper Orientation Contact plan Unit interface November 15 & 16, 2005 Groove Pierre KARST Flat Cone 25

Optical baffling studies November 15 & 16, 2005 Pierre KARST 26

Cold test: preliminary lay out 1/5 • Specific requirement: Vacuum < 10 -5 mbar Existing cryostat External illumination source unit: view port T° demonstrator < T° IR detector Diameter 180 mm 60 mm IR detector requirement: ü T° = 120 ± 5 K, stability 0. 5 K ü Temperature fluctuation max < 1 K/minute ü 1 short signal cable (20 cm) connected to a electrical board at room temperature November 15 & 16, 2005 Pierre KARST 27

Cold test: preliminary lay out 2/5 Herschel cryostat • • View port Several available feedthroughs for the electrical output. Clean room It is equipped with two cryonegic heads November 15 & 16, 2005 Pierre KARST 28

Cold test: preliminary lay out 3/5 Overview Viewport Signal cable feedthrough Cryogenic devices November 15 & 16, 2005 Pierre KARST 29

Cold test: preliminary lay out 4/5 • Overview avant le detecteur Signal cable Thermal baffling November 15 & 16, 2005 Pierre KARST 30

Cold test: preliminary lay out 5/5 • IR detector on the demonstrator Bench IR detector support November 15 & 16, 2005 Pierre KARST 31

Conclusion • This preliminary design meets the requirements • Next steps, we have: - To finish the slicer unit concept - To detail thermal studies - To define the optical baffling - To adapt the bench to the interfaces and thermal constraints November 15 & 16, 2005 Pierre KARST 32

Spares • • • Cut view of the mirror mount Alignment benches Herschel cryostat dimensions Mechanical description of the visible detector Slicer unit Shrinkage November 15 & 16, 2005 Pierre KARST 33

Alignment bench : spectrograph unit November 15 & 16, 2005 Pierre KARST 34

Alignment bench : Offner relay unit November 15 & 16, 2005 Pierre KARST 35

Cylindrical mirror mount November 15 & 16, 2005 Pierre KARST 36

Spares Herschel cryostat : Dimensions November 15 & 16, 2005 Pierre KARST 37

Visible detector Mechanical description November 15 & 16, 2005 Pierre KARST 38

SLICER UNIT November 15 & 16, 2005 Pierre KARST 39

Tolerance for adjustment at room T° Description Distan c e (mm) Shrinkage (mm) Required toler ance (mm) 0. 026 ± 0. 02 Slice mirror – 82 pupil. Description mirror Distance (mm) Tolerance for adjus tment (mm) 0. 014 (± 0. 007 Shrinkage )(mm) Required tolerance (mm) Tolerance for adjustment (mm) Spectro unit- Slicer unit 100 0. 032 ± 0. 16 Collimator - Prism 200 0. 064 ± 0. 1 ± 0. 036 Prism - Camera 135 0. 043 ± 0. 1 ± 0. 057 Description Distance (mm) Shrinkage (mm) Required tolerance (mm) Tolerance for adjustment (mm) Spectro unit- Offner relay unit 330 0. 106 ± 0. 2 ± 0. 094 OPM - OSM 100 0. 032 ± 0. 1 ± 0. 068 Description Steering unit- Slicer unit November 15 & 16, 2005 Distance (mm) Shrinkage (mm) 250 0. 08 Pierre KARST Required tolerance (mm) ± 0. 2 Tolerance of adjustment (mm) ± 0. 12 40