1 / 15

CCD Procurement

CCD Procurement. Schedule driven Review off-the shelf availability Specific mode of operation – match requirements ? Review test, characterisation and calibration requirements. Schedule. 2007 launch is the goal (match Kepler and be available for launch in the Herschel/Planck context)

ellema
Download Presentation

CCD Procurement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CCD Procurement • Schedule driven • Review off-the shelf availability • Specific mode of operation – match requirements ? • Review test, characterisation and calibration requirements

  2. Schedule • 2007 launch is the goal (match Kepler and be available for launch in the Herschel/Planck context) • For the AIV campaign, need focal camera ready in 2005 (details to be evaluated with system study, e.g. need dates, serial or parallel, calibration) • CCDs are the long-lead item to ensure delivery of chips for camera testing in 2004

  3. Schedule (ii)

  4. E2V Devices • CCD 42 family – used in Megacam, COROT • Set of common photo-lithographic mask components can be used to make a device 2048 w x (nx256) h • Can be used with shielded store section in framestore mode for minimal image smear & fast image readout • Back-illuminated, uniform response, switchable gain stage • Note the E2V design team is already loaded up with new projects

  5. Area vs Speed Trades • Large CCD covers more target stars per observation, but serial read out increases frame period • For fixed CCD full-well, longer frame time implies saturation at fainter magnitude • Serial output register becomes bottleneck – speed of amplifier (<3MHz) • Row binning is ”instantaneous” and serial register can accommodate ~3 – 4 image pixels • Two ampliers possible – doubles video electronics resources, CCD window reconstitution at middle

  6. CCD42-C0 • Largest device accommodated on Si wafer • 3072 x 2048 image pixels. • 6 CCDs cover field of view efficiently • All other parameters identical with CCD42-80

  7. Modes of Operation • Frame transfer, 4 (3?) rows binned to output, serial register runs 2.5MHz to one amplifier => 0.75 sec • Full well implies ~13 M electrons /star/sec mv ~7.7 (assuming m =11 ~6e5, but maybe 1 mag gain via. throughput estimate?) • To enhance brightness limit reduce accumulation time. Requirement of mv=5 implies reduce by >10 • Either reduce height of the selected area in a CCD to 300 rows or 0.23º x 1.6 º in one CCD • Or use a timed accumulation and low duty cycle in one CCD (5% live time) • Needs careful management for cross-talk

  8. Modes (contd.)

  9. Specification • Item Goal Spec Performance • Field View 6º dia. 2.5º dia 4.75 º x 4.75 º • Brightest star mv = 3 mv = 5 mv = 5 (7.7) • Faintest Star 15 15 14.8 • Dyn. Range 6 6 9.8 (7.1) • * Asteroseismology requirements (check also PF)

  10. Other items • Improved yield and uniformity if relax the short wavelength QE requirement • Noise – limited by design for high dynamic range (~15-20 electrons rms), run in low gain? • E2V rely on standard silicon, so do not push for higher resistivity and enhanced red response • Cosmetics - drive yield . Design the software to allow to ignore 1 pixel out of any star window – relaxed cosmetic spec. follows • Radiation damage, speed vs. electronics………..

  11. Testing Task Overview • Three separate areas of testing to be considered vis a vis industry procurement • Acceptance test against specifications • Radiation damage assessment • Test in support of algorithms, calibration, cosmic rays, photometric test bench etc..

  12. Performance verification • Does the representative prototype device meet our requirements? - Which are critical items? • Explore the yield of further devices to gain handle on unit cost • Measure several devices to gauge dispersion • Engineering devices to test out bread-board electronics • What can be done with CCD42-80? How many devices? Any front-illuminated from prototypes?

  13. Batch Acceptance • From the Flight Model batch verify the CCDs meet specifications • E2V can (and have – Megacam ?) perform this, but a testing bottleneck • Leave to industry camera team – efficient use of time and resources • “Eddicam” consortium – adds a possible delay between E2V and camera team at industry that may not be viable ? • Representative sampling ?

  14. Radiation damage • Eddington is likely a benign application w.r.t. radiation damage of charge transfer – image field is repetitive and unchanging, only stability is needed • Operate at as low a temperature as possible • Small change in apparent centroid, some loss of S:N • Take a representative CCD42 device, and test in Eddicam mode of operation and signal levels after representative dose • Bad pixel generation ?

  15. Science • Test performance in the modes of operation • Effects of long duration photometry (cosmic rays, flickering pixels, chosen on-board algorithms etc.) • Different requirements of test bench? • Can be CCD42-80 ? • On-ground calibration • Prepare for in-flight calibration • End-to-end test ? • Decoupling from industry effort is efficient

More Related