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SOT instrument overview

SOT instrument overview. Kiyoshi Ichimoto NAOJ. Hinode workshop , 2007.12.8-10, Beijing. Solar Optical Telescope SOT = OTA + FPP. OTA: f 50cm Gregorian Telescope. FPP:. M2. HDM (Heat Dump Mirror). 1.5m. Optical Telescope Assembly (OTA),

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SOT instrument overview

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  1. SOT instrument overview Kiyoshi Ichimoto NAOJ Hinode workshop, 2007.12.8-10, Beijing

  2. Solar Optical Telescope SOT = OTA + FPP OTA: f50cm Gregorian Telescope FPP: M2 HDM (Heat Dump Mirror) 1.5m Optical Telescope Assembly (OTA), is a Gregorian telescope with 50 cm aperture, built by NAOJ/ISAS. Focal Plane Package (FPP), includes observation filters, spectrometer, and cameras , built by LMSAL/HAO/NASA. M1 CLU (collimator Lens Unit) PMU (Polarizaiton Modulator Unit) Tip-tilt mirror

  3. SOT system overview

  4. SOT (Solar Optical Telescope): OTA FPP OBU

  5. Key Features of SOT • Largest telescope ever built to observe the Sun from space • Diffraction-limited images (0.2-0.3arcsec), achieved by 50-cm-diameter aperture • Observation from space, free from the atmospheric seeing. • Continuous observation for 24 hours per day in ~8 months per year, thanks to the sun-synchronous orbit of HINODE • Stabilized image with the correlation tracker • 388-668nm range, including spectral lines and continuums useful for studying photosphere and chromosphere • Optimized for high precession polarization measurements in spectral lines, continuous modulation of Stokes IQUV in every 0.8sec. • Provides accurate vector magnetic fields in the photosphere.

  6. Optical layout of SOT LitrowMirror Polarizing BS Folding Mirror Spectoro-polarimeter Dual 256 x 1024 CCD X3 Mag lens Polarizing BS Folding Mirrors Shutter Slit Field lens Grating Field lens X2 Mag lens Filterwheel Shutter Preslit 4096 x 2048 CCD Filterwheel FieldMask Birefringent Filter Broadband Filter Instrument Narrowband Filter Instrument 50 x 50 CCD Secondary Telecentric lenses Correlation Tracker BeamDistributor Demag lens HDM Folding Mirror ReimagingLens Image Offset Prisms Folding Mirror OTA Astigmatism corrector lens Color Coding OTA Common Optics CT NFI BFI SP Primary PolarizationModulator CLU Tip TiltMirror

  7. SOT Optical Telescope Assembly (OTA)

  8. Gregorian telescope Aperture area f500mm, 153434mm2 Linear central obscuration 0.344( = 172/500 ) HDM outer diameter 32.83mm (Maximum offset pointing angle) Effective f-length at secondary focus 4527 25 mm Effective F-ratio at secondary focus 9.055 0.05 Plate scale at secondary focus 21.95 mm/arcsec Field of view 360 x 200 arcsec Exiting beam Collimation Collimated in air Angular magnification 16.667 Exit pupil size f30.0 mm Exit pupil position -73.05 from tip-tilt mirror Chromatic aberration Nearly zero (<35mm 388—670nm) Optical parameters of OTA

  9. 40 mm +Y 172 mm 500 mm Point Spread Function　（ideal）

  10. 5. OTA flight model integration clinometer Vertical meter Target mirror Reference flat Alignment cube M2 Dummy OBU OTA Rotation mechanism Interferometer MiniFiz M1 Six axis stage Telescope Up Optical bench • OTA is integrated on a dedicated tower. • Interferometoric measurement is performed with f60cm reference flat at the top of tower. • OTA can be upside top and upside down to cancel gravity.

  11. Example of WFE map Average of upside top and upside down gives the Zero-G WFE Gravitational deformation of OTA optics ~ l/20 rms @633nm

  12. OTA Opto-thermal testing -- motivation -1.7~ 25.0 C Heater control -21.5 ~ 4.4C -27.8 ~ 4.6C 21.1 ~ 67.3 C 1.1 ~ 16.3 C 19.9 ~ 43.2 C 16.0 ~ 30.0 C 26.2 ~ 45.7 C Heater control Predicted OTA temperature in orbit Large DT from the ground testing. Large dT/dz.

  13. OTA Opto-thermal testing -- configuration Reference mirror  OTA pointing ax. Theodolite  OTA center of FOV Upper shroud OTA interferometer Dummy OBU Support theodlite  alignment cube. Lower shroud OTA alignment cube flat mirror shroud Flat mirror reference Tilt/shift stage Autocollimator  OTA pointing ax. WFE of OTA is measured in a dedicated vacuum chamber. Two shrouds control the OTA temperature as it is in orbit.

  14. Maximum offset pointing of SOT Heat Dump Mirror at primary focus focus D◎=32’35” Sun SOT FOV max.offset = 19.6’ margin ～1.2’ HDM outer diameter32.83mm Maximum offset of Hinode pointing = 19.6 arcmin

  15. M1 (FM sample) M2 (FM sample) CTM-TM (theoretical) CLU (FM measurement) BFI wavelengths NFI wavelengths

  16. SOT Focal Plane Package (FPP) SP Littrow Mirror SP CCD Radiator SP Littrow Grating BFI/NFI Beam Combiner SP CCD Electronics SP Slit BFI Shutter BFI Filterwheel NFI Focalplane Mask Beam Distributor SP Slit Scanner NFI Shutter BFI/NFI CCD Radiator NFI Lyot Filter BFI/NFI CCD Electronics NFI Filterwheel CT CCD Electronics CT wedge wheel FPP Mechanical Design

  17. HINODE SOT has four optical paths: • < aims > • Broadband Filter Imager (BFI) images with highest spatial resolution • Narrowband Filter Imager (NFI) wide FOV, high resol. mag./Dopp., chrom. • Spectro-Polarimeter (SP) precise photospheric magnetic fields • Correlation Tracker image stabilization

  18. Basic parameters of four optical paths: BFI NFI SP CT CCD format 4096 x 2048 112 x 1024 x 2 50 x 50 pixel scale (arcsec/pix) 0.054 0.08 0.16 0.22 maximum FOV (arcsec2) (EWxNS) 218x109 328x164 328 (scan range) x164 (slit length) 11x11 wavelength resolution (A) 3~10 ~0.1 0.02 5 number of wavelength in a data set 1 1~4 244 1 time resolution (typical) 5~30s 10~60s 1min~3hr 580Hz photometric aquracy (%) 0.5 0.1 ~ 0.5 ~ 0.1 ~0.5

  19. Field of view 218" × 109" (full FOV) CCD 4k × 2k pixel (full FOV), shared with the NFI Spatial Sampling 0.0541 arcsec/pixel (full resolution) Spectral coverage Center (nm) Width (nm) Line of interest Purpose 388.35 0.7 CN I Magnetic network imaging 396.85 0.3 Ca II H Chromospheric heating 430.50 0.8 CH I Magnetic elements 450.45 0.4 Blue continuum Temperature 555.05 0.4 Green continuum Temperature 668.40 0.4 Red continuum Temperature Exposure time 0.03 - 0.8 sec (typical) SOT broadband filters

  20. Field of view 328"×164" (unvignetted 264"×164") CCD 4k×2k pixel (full FOV), shared with BFI Spatial sampling 0.08 arcsec/pixel (full resolution) Spectral resolution 0.009nm (90mÅ) at 630nm Spectral windows (nm) and lines of interest Center l-range Lines geff Purpose 517.2 0.6 Mg I b 517.27 1.75 Dopplergrams and magnetograms 525.0 0.6 Fe 524.71 2.00 Photospheric magnetograms Fe I 525.02 3.00 Fe I 525.06 1.50 557.6 0.6 Fe I 557.61 0.00 Photospheric Dopplergrams 589.6 0.6 Na I D 589.6 1.33 Very weak fields (scattering polarization)Chromospheric fields 630.0 0.6 Fe I 630.15 1.67 Photospheric magnetograms Fe I 630.25 2.50 Ti I 630.38 0.92 Umbral magnetograms 656.3 0.6 H I 656.28 ~1.3? Chromosphreic structure Exposure time 0.1 - 1.6 sec (typical) SOT narrowband filter

  21. Field of view along slit 164" (north-south direction) Spatial scan range ±164" Slit width 0.16" Spectral coverage 630.08nm - 630.32nm Spectral resolution 27mÅ / 21.53 mÅ sampling Measurement of polarization Stokes I,Q,U,V simultaneously with dual beams (orthogonal linear components) Polarization signal to noise 103 (with normal mapping) SOT SP (Spectro-Polarimeter) • Fe I 630.15nm and 630.25nm • Obtain spectra at 16 angular positions of polarization modulator • 83min for 160" wide scan

  22. Solar-B Fields of View N EIS (360”x512”) E W SOT:BFI (205”x102”) SOT:NFI/SP (328”x164”) XRT (2048”x2048”) S SOHO/EIT FeXII 195A

  23. HDM hole, f505” or 2.864mm @f1 Vignetting by tunable filter 40 % 52.5” or 0.3mm @f1 20 % 0 % 16.8” or 0.37mm @f2 Field stop at f2, 361.3” x 197.4” or 7.93 x 4.33 mm2 @f2 183.2” 163.8” CCD of BFI 327.7” CCD of NFI / SPG scanning

  24. Schematics of the SOT polarimeter Polarization modulator unit (PMU) OTA Collimator lens unit (CLU) HDM CTM-TM Pupil image Astigmatism corrector lens (ACL) M2 M1 NFI- Polarization analyzer Mask wheel Mech. shutter Reimaging lens Tunable filter FG/NFI Non-polarizing beam splitter FG-CCD Blocking filter wheel SP Slit scan mirror Slit SP- Polarization analyzer (beam splitter) SP-CCD left/right

  25. Polarization modulator Waveplate: Common for FG/SP (PMU) Continuous rotation, 1.6sec/rot Retardation:N+0.35l @632nm and 517nm

  26. WP:d PL Polarization modulation PMU segment 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Q V U

  27. Polarization sampling 16-pos. continuous readout 4-pos. (example) SP, NFI shutterless Mod. cycle = 0.8sec ε ~0.1% NFI shuttered Mod. cycle > 5sec ε ~0.5%

  28. NFI shutterless mode Mask off outer parts of CCD by focal plane mask Continuous readout (10frame/sec) without operating the mechanical shutter On-board demodulation and accumulation to achieve high S/N FG CCD Size of focal plane mask Transfer speed = 6.15msec/pix 16” x 163.8” 32” x 163.8” 64” x 163.8” 128” x 163.8” 164” x 163.8” 328” x 163.8” 1024 pix shift = 6.30msec 6.30ms/1600ms*360*2 = 2.83 deg. azimuth rotation

  29. SOT observables FG: - simple image - Dopplergram (2 wavelengths) - Stokes IV - Stokes IQUV - IVDG (2 wavelengths) SP: - normal mode (0.16” step, 4.8s/slit) - fast mode (0.32” step, 3.2s/slit) - dynamic mode (0.16” step, 1.6s/slit) - deep mode (0.16” step, 9.6s/slit)

  30. Observation planning Time res. # of wavelength (reliability) 1sec 64 10sec 16 1min Data rate （4k*2k*100/2s ~ 1GB/sec） 10min 4 2 1hr 1 1day FOV 10” 100” 1000” Spatial res. 1” 0.4” 0.2” 0.1” 1min 1% 1hr 0.1% 1day 1week 0.01% Random noise (detection limit) Time span SOT limit performance SOT limit ~104 times larger than telemetry limit (0.3Mbps)

  31. Time res. # of wavelength (reliability) 1sec 64 3D dynamics 10sec 16 1min 10min 4 2 1hr 1 1day FOV 10” 100” 1000” Spatial res. 1” 0.4” 0.2” 0.1” 1min 1% 1hr 0.1% 1day 1week 0.01% Random noise (detection limit) Time span Flux tube dynamics: local physical process energy flow into corona

  32. Time res. # of wavelength (reliability) 1sec 64 10sec 16 1min 10min 4 2 1hr 1 1day FOV 10” 100” 1000” Spatial res. 1” 0.4” 0.2” 0.1” 1min 1% 1hr SOT/SP full scan 0.1% 1day 1week 0.01% Random noise (detection limit) Time span AR energetics: global energy storage

  33. Time res. # of wavelength (reliability) 1sec 64 10sec 16 1min 10min 4 2 1hr 1 1day FOV 10” 100” 1000” Spatial res. 1” 0.4” 0.2” 0.1” 1min 1% 1hr 0.1% 1day 1week 0.01% Random noise (detection limit) Time span Origin of mag.field: emerging flux/ internetwork flux disappearance

  34. SOT observation table

  35. Solar Optical Telescope on HINODE 2006.9.23

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