Integral Field Spectrograph Eric PRIETO CNRS,INSU,France,Project Manager 11 November 2003

2 Spectrograph characteristics Property VisibleIR Wavelength coverage (  m) Field of view 3.0"  6.0" Spectral resolution,  Spatial resolution element (arc sec)0.15 detectors LBL CCD 10  m HgCdTe 18  m Efficiency with OTA and QE>40%>30%

3 Spectrograph: Functional Overview Relay Optics Slicer Unit Collimator Prisms Dichroics NIR CAM VIS CAM NIR Focal plane Visible Focal plane Shutter Dithering Thermal control Interface Electronics Science Software Calibration lamps OCU

4 optics with 7 mirrors two arms configuration Two prisms Pre optical design Visible detector IR detector slicerprisms entrance

5 Entrance beam IR detector Visible detector Floppy interface Fix point 180 mm dL=180 x ( ) x 1, = 0,038 mm 420 mm dL= 0,02 mm dL = 0,09

6 Optical bench (Invar) weight =2,3Kg Structural support (Molibdenu m) weight =2,7Kg Floppy interface Fix point ( nearest of the entrance beam point ) Structural support fix on the cold plate Displacement is amplify

7 Instrument road map Primary SNAP specifications Concept definition Pre conceptual design Detailed simulation New requirements Conceptual design Define system requirements Prove the feasibility Verify performances Budget errors First requirements Interface control document

8Implementation:

9 Optical design (option1)

10 Slicer Design:

11 Focal plan development No ‘single point failure’ => Only detectors are to be duplicate: two detectors and their electronic: Field of view of 3’’X6‘’ instead of 3’’X3’’Field of view of 3’’X6‘’ instead of 3’’X3’’ Need 40 slicesNeed 40 slices No effect on opticNo effect on optic

12 Performance: efficiency # elements Efficiency /elements Cumulative efficiency Telescope Relay optic Slicer (mirrors + straylight + diffraction) Spectrograph Mirrors 2 Prism Dichroic Visible Detector IR Detector

13Performances Zeemax optimisation Simulation result

Integral Field Spectrograph: R&T Slicer Eric PRIETO CNRS,INSU,France,Project Manager 11 November 2003 (on behalf: ESA Slicer Prototype Team: LAM/CRAL/Durham More specifically: Charles Maccaire and Florence Laurent)

15SCOPE ESA Funded prototyping work JWST/NIRSPEC development Previously MEMS back-up Currently IFU option Collaboration LAM/CRAL/DURHAM Aim: Technical Readiness Level 6

16 Slicer Principle 1.Field divided by slicing mirrors in subfields (40 for SNAP) 2.Telescope pupil on the pupil mirrors 3.Aligned pupil mirrors 4.Sub-Field imaged along an entrance slit How to rearrange 2D field to enter spectrograph slit:

17 Optical Design Slice mirrors Slit mirrors array Pupil mirrors array Steering mirror

18 Design Overview Active Stack Heel Stack support Steering mirror Pupil mirror array Slit mirror array Main structure Substructure Thrust cylinders Dummy Stack

19Reality

20 Reality: Image Slicer (uncoated) Support 18 “Flat” Slices (Dummies) 10 “Curved” Slices (Actives) 2 “Flat” Slices (Dummies)

21 Slicing-mirror stack measurements Images of the two scans common reference surface one slicing mirror is present in both scans and can be used to check results

22 Slicing-mirror stack measurements Results positioning accuracy includes both assembly and manufacturing errors Xc within +/- 22 µm from nominal Yc within +/-22 µm (except n°6) from nominal (measurement errors contribute to probably ~10 µm) to be compared to the +/-20 µm requirement

23 Pupil/slit mirrors lines Opto-Mech. Mount 5 Pupil Mirrors 1 Broken Mirror Glass Bar Optical contact released during manipulation New assembly will be produced compatible with vibration specifications Back-up solution from monolithic solution

24 Pupil-mirror line measurements damaged mirror to the right scratches on the left-mirror are outside the usefull area (pupil size)

25 Pupil-mirror line measurements Comparing the curvature center locations remove a slope compare with expected positions Results positioning accuracy includes both assembly and manufacturing errors both Xc and Yc are within +/- 5-6 µm from their nominal positions (probably need to add a few µm of measurement accuracy) to be compared to the +/- 20 µm requirement  the pupil mirror line meets the relative alignment requirements

26 Slit-mirror line measurements 5 identical mirrors overall slope (will be removed during analysis)

27 Slit-mirror line measurements Comparing the curvature center locations remove a slope compare with expected positions Results positioning accuracy includes both assembly and manufacturing errors both Xc and Yc are within +/- 8 and even 1 µm from their nominal positions (probably need to add a few µm of measurement accuracy) to be compared to the +/- 20 µm requirement  the pupil mirror line meets the relative alignment requirements

28 First Results: Pupil plane Impressive alignment of the pupils on the pupil mirrors Positioning alignment within 50µm (pitch: 2.75mm) Surface defect and edges are due to manipulation accident (assembly weakness) New line will be produced (stronger)

29 First PSF results Preliminary results PSF Size in agreement with simulation Astigmitism & coma (as theory) Rotation along the slice TBD: deconvolve with instrumental PSF

30 First Results: Slit plane Impressive alignment of the virtual slits on the slit mirrors Positioning alignment within 20µm (pitch: 2.75mm)

31 Thermal / Structural tests Low level vibration tests performed: first mode 185hz Sinusoidal tests will be performed 20g (40g if possible) Random tests will be performed 15g (30 if possible) First test of optical mount at 77°K performed Full prototype will be 30-40°K (dec 03) Inside Liquid Nitrogen

32 Current output System expertise demonstrated Optical manufacturing demontrated Optical performance compliant To be done: thermal qualification (Dec 03) To be done: vibration qualification (Dec 03) Re-manufacture pupil line for vibration (April 04)