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Integral Field Spectrograph Eric PRIETO CNRS,INSU,France,Project Manager 11 November 2003 Spectrograph characteristics Property Visible IR Wavelength coverage (m) 0.35-0.98 0.98-1.70 Field of view 3.0" / 6.0" 3.0" / 6.0" 70-200 70-100 0.15 0.15 LBL CCD 10 m HgCdTe 18 m >40% >30% Spectral resolution, l/dl Spatial resolution element (arc sec) detectors Efficiency with OTA and QE 2 Spectrograph: Functional Overview Shutter Slicer Unit Relay Optics Calibration lamps Collimator Dithering Science Software Thermal control OCU Prisms Dichroics VIS CAM NIR CAM Visible Focal plane NIR Focal plane Interface Electronics 3 Pre optical design • optics with 7 mirrors • two arms configuration • Two prisms IR detector Visible detector entrance prisms slicer 4 Entrance beam Floppy interface dL = 0,09 Fix point Visible detector dL=180 x (300-140) x 1,3.10-6 = 0,038 mm IR detector 5 Fix point (nearest of the entrance beam point) Floppy interface Displacement is amplify Optical bench (Invar) weight =2,3Kg Structural support fix on the cold plate Structural support (Molibdenu m) weight =2,7Kg 6 Instrument road map Primary SNAP specifications First requirements 2002 Define system Concept definition requirements Pre conceptual design 2003 Prove the feasibility Detailed simulation Interface control document New requirements 2004 Verify performances Budget errors Conceptual design 7 Implementation: IFS Telescope focal plane Dark zone Telescope 8 Optical design (option1) 9 Slicer Design: Telescope Focal Plane Spectrograph Slit mirrors : Spectrograph Slit Folding mirrors Pupil mirrors Slice mirrors Fore- mirror 10 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’’ •Need 40 slices •No effect on optic 11 Performance: efficiency # elements Efficiency /elements Cumulative efficiency Telescope 4 0.98 0.92 Relay optic 1 0.98 0.90 0.82 0.71 Spectrograph Mirrors 2 Prism Dichroic 0.98 0.81 0.95 0.57 Visible Detector 1 0.9 0.52 IR Detector 1 0.8 0.42 Slicer (mirrors + straylight + diffraction) 12 Performances Spectral resolution for the visible detector 295 275 255 235 215 195 175 155 135 115 95 75 Simulation result Spectral resolution for the IR detector lambda 0,4 0,5 0,6 0,7 0,8 0,9 1 110 105 100 95 90 85 80 Zeemax optimisation 75 lambda 70 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 13 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) SCOPE • ESA Funded prototyping work • JWST/NIRSPEC development • Previously MEMS back-up • Currently IFU option • Collaboration LAM/CRAL/DURHAM • Aim: Technical Readiness Level 6 15 Slicer Principle How to rearrange 2D field to enter spectrograph slit: 1. Field divided by slicing mirrors in subfields (40 for 4 SNAP) 2. Telescope pupil on 1 the pupil mirrors 3. Aligned pupil mirrors 3 4. Sub-Field imaged 2 along an entrance slit 16 Optical Design Slit mirrors array Slice mirrors Pupil mirrors array Steering mirror 17 Design Overview Dummy Stack Pupil mirror array Slit mirror array Active Stack Heel Stack support Thrust cylinders Substructure Main structure Steering mirror 18 Reality 19 Reality: Image Slicer (uncoated) Support 18 “Flat” Slices (Dummies) 10 “Curved” Slices (Actives) 2 “Flat” Slices (Dummies) 20 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 21 Slicing-mirror stack measurements DXc (mm) Slices m irrors curvature center DX default m easured w ith the STIL m achine 0,025 0,020 0,015 0,010 0,005 0,000 -0,005 -0,010 -0,015 -0,020 -0,025 1 2 3 4 5 6 7 8 9 Results • positioning accuracy includes both assembly and manufacturing errors 10 •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 slice num ber (1: sclice 28; 10: slice19) Slices m irrors curvature center DY default m easured w ith the STIL m achine 0,050 0,040 DXc (mm) 0,030 0,020 0,010 0,000 -0,010 1 2 3 4 5 6 7 8 9 10 -0,020 -0,030 slice num ber (1: sclice 28; 10: slice19) 22 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 23 Pupil-mirror line measurements • damaged mirror to the right • scratches on the left-mirror are outside the usefull area (pupil size) 24 Pupil-mirror line measurements MP_regresse 0,01 0,005 x y 0 1 2 3 4 5 Comparing the curvature center locations • remove a slope • compare with expected positions -0,005 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 25 Slit-mirror line measurements • 5 identical mirrors • overall slope (will be removed during analysis) 26 Slit-mirror line measurements MF_RégressionLinéaire 0,006 0,004 0,002 0 -0,002 -0,004 x 1 2 3 4 5 y Comparing the curvature center locations • remove a slope • compare with expected positions -0,006 -0,008 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 27 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) 28 First PSF results • Preliminary results • PSF Size in agreement with simulation • Astigmitism & coma (as theory) • Rotation along the slice • TBD: deconvolve with instrumental PSF 29 First Results: Slit plane • Impressive alignment of the virtual slits on the slit mirrors • Positioning alignment within 20µm (pitch: 2.75mm) 30 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 tested @ 30-40°K (dec 03) Inside Liquid Nitrogen • 31 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) 32