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James Beletic Rockwell Scientific Company

A new CCD optimized for pulsed laser guide star wavefront sensing Principal Investigator Co-Investigators. James Beletic Rockwell Scientific Company

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James Beletic Rockwell Scientific Company

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  1. A new CCD optimized for pulsed laser guide star wavefront sensingPrincipal InvestigatorCo-Investigators James BeleticRockwell Scientific Company Sean AdkinsKeck ObservatoryBarry BurkeMIT Lincoln LaboratoryCharlie BleauSciMeasure Analytical SystemsRay DuVarneySciMeasure Analytical Systems Jerry NelsonUniv. California, Santa CruzRichard StoverLick ObservatoryFrancois RigautGemini Observatory

  2. Planar JFET performance? Project purposeMake AO CCDs* photon-noise limitedGoal: 1e- noise at 1 kHz frame rate • Significantly reduce • readout noise • Increase # of readout ports • & use best MOSFET design • Test the new planar JFET (& use many ports) • Use novel design to optimally sample LGS photons

  3. Project Phases • Produce and test a standard geometry CCD • 160 x 160 pixel image array • 18 or 21 micron pixels • Split frame transfer • 20 readout ports • Best MOSFET • Planar JFET

  4. 10 readout ports 80 x 160 pixel 1/2 frame storage 160 x 160 pixel image area 16 x 80 pixels read out of a single port lower 1/2 frame storage 10 readout ports

  5. L d LGS optimized AO CCD • Challenges: • LGS spot elongation • WFS CCD: - Readout noise - Readout time • Assume: • Shack-Hartmann WFS

  6. LGS spot elongation in a specific subaperture is a function of: • Laser-subap separation • Altitude of Na layer • Thickness of Na layer • Altitude of telescope • Zenith angle • Mount (az-el) • AO system location 8-10 meter telescope20 subapertures across the pupil

  7. Shack-Hartmann subapertureimage plane geometry

  8. Shack-Hartmann subaperture image plane geometry

  9. Can bin to 2x2 pixels Shack-Hartmann subaperture image plane geometry More photons per pixel Faster Readout Higher SNR Lower Readout Noise

  10. Serial Register Video output LGS spots in each subaperture Detail of pixel array for corresponding LGS spot Wavefront sensor subapertures shown with respect to telescope primary mirror Clock Lines

  11. Pulsed laser overcomes spot elongation Pulsed Laser CW Laser

  12. Can track laser pulse acrossa single subaperture Spot travel direction

  13. Dump Drain Vdump drain Image Array I1 Video Out I2 I3 Frame Storage FS1 FS2 FS3 Voutput gate Serial Register 2 stage amplifier S1 S2 S3 SW Output Select Summing Well reset 4 serial register pixels to to “warm up” electronics Reset Gate Phase 2 CCD Design - Subaperture Design

  14. Electronics and cryostat bySciMeasure Analytical Systems Come see a SciMeasure Camera System at this poster (with an “old time” e2v chip inside)

  15. Phase 1 CCD • 160 x 160 pixel std. geometry • Test planar JFET • Results 2005 • Phase 2 CCD • Pulse LGS geometry • Design 2005 • use best phase 1 amp • Fab / test 2006 10 readout ports 80 x 160 pixel 1/2 frame storage 160 x 160 pixel image area 16 x 80 pixels read out of a single port lower 1/2 frame storage 10 readout ports AO CCD Project Plan

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