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ATST Cameras (presentation for HAO only) David Elmore

ATST Cameras (presentation for HAO only) David Elmore. Instrument Control System Interfaces. Scripts. OCS 4.2. Users. ICD 3.1-4-4.2. DHS 4.3. ICS 3.1.4. TCS 4.4. ICD 3.1.4-3.2. ICD 3.1.4-3.3. ICD 3.1.4-3.4. ICD 3.1.4-3.5. ICD 3.1.2-3.1.4. ICD 3.1.1-4.4. BDT 4.3.1. VBI 3.2.

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ATST Cameras (presentation for HAO only) David Elmore

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  1. ATST Cameras(presentation for HAO only)David Elmore

  2. Instrument Control System Interfaces Scripts OCS 4.2 Users ICD 3.1-4-4.2 DHS 4.3 ICS 3.1.4 TCS 4.4 ICD 3.1.4-3.2 ICD 3.1.4-3.3 ICD 3.1.4-3.4 ICD 3.1.4-3.5 ICD 3.1.2-3.1.4 ICD 3.1.1-4.4 BDT 4.3.1 VBI 3.2 ViSP 3.3 NIRSP 3.4 VTF 3.5 Synchrobus 3.1.2 GOS 3.1.1 ICD 3.2-3.6 ICD 3.3-3.6 ICD 3.4-3.6 ICD 3.5-3.6 ICD 3.1.1-3.1.2 Cameras 3.6 ICD 3.6-4.3 ICD 3.1.2-3.6 Synchrobus Data LAN

  3. Facility • Cameras are an ATST Facility • Interfaces to instruments, modulators, and data transport is standardized via ATST CSF • Common camera software minimizes development time and maintenance • Special cases are minimized • Instrument builders can share camera control software

  4. Virtual • Images • Accumulated modulation states: N frames into M states • Bursts: Collect N frames at a rate faster than BDT can accept – then spool them out • Frame selection: Record frames at a high rate, select only the ‘best’ on the fly and send them to BDT • Monitor: Send frames to BDT at a rate that can be continuously displayed by DHS

  5. Services • Focus: Virtual cameras compute contrast values of identified features and continuously send values back to the controlling instrument to servo focus • Alignment: Virtual cameras compute the pixel coordinates of identified features and continuously send coordinates back to the controlling instrument to servo camera rotation and translation

  6. Synchronization • Virtual cameras contain absolute time board and wave form generator • Controlling experiment sends synchronization information to cameras • modulator start time, modulation rate, and phase at t=0 • time to start accumulations • trigger details such as sign and duty cycle (exposure time) • VCs then produce images according to settings

  7. Sensor requirements • Size • ViSP: 4k X 4k to sample 2’ at 2x diffraction limit at 600nm and handle multiple slits • VBI: 8k X 8k for 2’ diffraction limit at 600nm, 12k x 12k for diffraction limit at 400nm • ISRD indicates a willingness to compromise instantaneous field of view for other camera parameters and ability to raster • VTF: 4k X 4k for 1’ diffraction limit at 550nm • NIRSP: 2k X 2k for 2’ at 2x diffraction limit at 1.2 microns

  8. Sensor requirements • Full well and read noise • 100,000e- full well and <50e- read noise: Gives >40:1 dynamic range over the image

  9. Seeing-induced cross talk I,Q,U,V vary by 100% in 1/8 arc second Solar feature model DST excellent seeing with tip-tilt correction Atmosphere ATST M1 & M2 polarization, Al coated mirrors Telescope polarization Rotating 0.375 wave retarder Polarization modulation Conclusions for ViSP: -100Hz required for dual beam analysis -Many kHz required for single beam Time varying polarization from Gregorian focus to ViSP Relay optics polarization Single or Dual Beam Polarization analyzer 100Hz to 1600Hz Detector

  10. Image Reconstruction • The SWG decided upon speckle reconstruction over Multi-Object Multi-Frame Blind Deconvolution (MOMFBD) or Phase diversity (PD) • Approximately 100 short frames are required that freeze seeing but sample different seeing realizations • solar features change on a time scale of 3 seconds (at VBI resolution) • Conclusion • ~10msec exposures • 30 frames/second for ~3 seconds

  11. Sensor requirements • Frame Rate • 100 frames/second for high polarimetric accuracy (ViSP) • 30 frames/second for imagers using image reconstruction (VBI, VTF, context cameras)

  12. Sensor goals • Many kHz charge-caching • Operationally allows for optimizing polarimetry at multiple instruments • Quantum efficiency > 0.75 over spectral range • Effectively increases the size of the telescope • Snapshot mode readout • Improves ability to perform image reconstruction

  13. Sensor goals • Exposure ‘gate’ • Operationally optimizes exposure times among multiple instruments • Butt-able • VBI can meet field of view requirements without rasterization

  14. Two Pronged Approach • FDR: Meet requirements • Field of view can be sequentially sampled and visible wavelength sensor technology is rapidly evolving, therefore select the best available visible wavelength detectors at the required time of purchase • currently 2352 X 1728 @ 60Hz frame rate • or 2352 X 1000 at 100Hz frame rate • Purchase currently available cameras for NIR • 2k X 2k, 76 frames/sec

  15. Two Pronged Approach • Outside of ATST • Pursue development funding for state of the art cameras meeting goals • 4k X 4k • 100Hz • snapshot mode • butt-able • gated • high QE • Include charge caching design in the development program (2k X 2k)

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