Transcript OSA talk
Focal Plane Array Testing and Applications for Astronomy Donald Figer Space Telescope Science Institute Outline The role of detectors in discovery. The state of the art in detectors. Keck/LGS/AO HST SOFIA Detectors and future Astronomy projects. LSST SNAP JWST The Role of Detectors Detector Functions Photometry Astrometry Spectoscopy Morphology Time Variability Detector Types Eye Film Photomultiplier tube CCD Photodiode array Radio Antennae Detector Wavelength Sensitivity X-ray Visible 0.1 0.3 Silicon NIR 0.9 1.1 2.5 MIR 5 HgCdTe InSb InGaAs l [mm] 20 CCD Architecture Hybrid Architecture Hybrid Architecture In bump light-sensitive layer substrate AR coating Keck Keck Keck Keck/AO/LGS HST: Hubble Space Telescope General-purpose orbiting astronomical telescope HST HST HST HST HST SOFIA: Stratospheric Observatory for Infrared Astronomy LSST: Large Synoptic Survey Telescope What is the distribution of dark matter in the Universe? What is dark matter? LSST SNAP: Supernova Acceleration Probe What is dark energy? SNAP Optical Configuration Telescope is a three-mirror anastigmat 2.0 meter aperture 1.37 square degree field Lightweight primary mirror Low-expansion materials Optics kept near 290K Transverse rear axis Side Gigacam location passive detector cooling combines Si & HgCdTe detectors Spectrometers share Gigacam focal plane Few moving parts in payload two-blade shutter for Gigacam focussers/adjusters at secondary & tertiary SNAP Focal Plane Concept Coalesce all sensors at one focal plane. Imager sensors on the front. 36 HgCdTe 2kx2k 18 mm 36 CCD 3.5kx3.5k 10.5 mm Filters 1 of 3 per HgCdTe 4 of 6 per CCD Spectrograph on the back with access ports through the focal plane. Exposure times of 300 s with four/eight exposures in CCDs/HgCdTe. JWST: James Webb Space Telescope What is the shape of the Universe? How do galaxies evolve? How do stars and planetary systems form and interact? How did the Universe build up it present elemental/chemical composition? What is dark matter? JWST 6.5m diameter primary mirror launch in 2013 orbit at L2 four scientific instruments JWST deployment movie IDTL: Independent Detector Testing Laboratory Located at Space Telescope Science Institute and Johns Hopkins University Founded 1999 Mission: Serve the astronomical community by developing and testing detectors for space and ground based astronomy programs Past and Present Personnel Eddie Bergeron Data Analyst Tom Reeves Lab Technician Robert Barkhouser Optical Engineer Mike Telewicz Intern Bernie Rauscher Project Scientist Utkarsh Sharma Graduate Student Gretchen Greene Mechanical Engineer Steve McCandliss JHU Lead Ernie Morse Data Analyst Monica Rivera Intern Scott Fels Intern Don Figer Director Russ Pelton Technician Sito Balleza Systems Engineer Mike Regan System Scientist IDTL Test System He Lines IDTL Test System Figure 3.3. Mechanical drawing of cross section of IDTL dewar assembly. The optics with ray trace are also shown. Figer et al. 2002, SPIE, 4850, 981 IDTL Sample Results: Persistence (1200 seconds) IDTL Sample Results: Read Noise IDTL Sample Results: Dark Current IDTL Sample Results Dark Current Dark Current Read Noise Short-wave Cutoff Persistence RQE vs. T Gain Long-wave Cutoff IDTL Comparartive Detector Characterization Properties of Silicon: QE Properties of Silicon: Long Wave QE Silicon 1 mm QE vs. Thickness & Temperature Properties of HgCdTe • Nearly “ideal” characteristics. • Many vendors. Properties of InGaAs: QE State of the Art: Thin CCD • Nearly “ideal” characteristics. • Many (~4) vendors. State of the Art: LBNL Thick CCD QE State of the Art: Si PIN • Emerging technology. • Chief Vendors - Raytheon Vision Systems (RVS) and Rockwell Scientifics Corp. (RSC). Comments / Notes Parameter Read Noise < 10e- with multiple reads 2 Dark Current ~ 1fA/cm , @-100C Radiation Tolerance Robust On Chip logic Yes (on stacked ROIC) Readout Method many choices, ripple, snap shot, subframe imaging, pseudo random Support Generally requires multiple biases but State of the Art: Si PIN RQE (100 mm thick) 1 1 140 K 0.9 140 K 0.9 160 K 160 K 180 K 180 K 200 K 0.8 0.7 0.7 0.6 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 400 500 600 700 800 Wavelength (nm) 900 1000 200 K 0.8 1100 0 800 850 900 950 Wavelength (nm) 1000 1050 1100 State of the Art: Si PIN Hybrid Arrays Si PIN Hybrid QE Measures Data (from B. Pain, et. al.) State of the Art: Si PIN Dark Current Si PIN Dark Current versus Temperature Dark Current (e-/s/pixel) 1.E-10 Dark Current (A/cm^2) 1.E-11 1.E-12 Temperature (K) 100 dark current 0.0001 120 140 160 180 200 220 0.0001 0.0004 0 0.4 14 300 1.E-13 0.001 in e-/s/pixel for 10(18 mm pixel noise H2RG-003 • QE@ 1mm 1.E-15 mm pixels) • 24%@140K • 28%@160K 1.E-16 • 1e- on reference pixels, • 33%@180K 1.E-17 Fowler-32, 100 kHz • 38%@200K 1.E-18 • 9e- on science pixels, • Crosstalk, 2-3% 90 100 110 100 120 kHz 130 140 150 160 170 180 190 200 210 220 Fowler-32, • Persistence, <0.3% Temperature (K) well depth, 120,000 e- 1.E-14 read 230 State of the Art: Si PIN Read Noise 10 e- State of the Art: HgCdTe Mature technology, although short-wave QE is recent development. Several vendors. Flight heritage NICMOS, 256x256, 2.5um cutoff. Hubble Wide Field Camera 3, H1RG, 2.3um cutoff. (Launch?) Deep Impact MRI spectrometer, H1RG, 5um cutoff. JWST NIRCam, NIRSpec, FGS, 2.5um and 5.0um cutoff. (Launch?) State of the Art: HgCdTe Dark Current State of the Art: HgCdTe Read Noise State of the Art: InGaAs • Emerging technology. • Sensors Unlimited State ofcontract the Art: SUI InGaAs DARPA to develop 1280 x 1024QE InGaAs Array. Dark current goal of 2nA/cm2. Read noise ~ 10e- at video rates. Worth watching. State of the Art: Photon Counting CCD Emerging technology. Two (more?) vendors. Low Light Level CCDs (L3CCDs), a.k.a. EMCCDs. Realized noise is 1.4 times value for non-photon counting mode. High read rate required in photon counting mode implies high power ~10 W per CCD for clocks and outputs.