Focal Plane Array Testing and Applications for Astronomy

Focal Plane Array Testing and Applications for Astronomy Donald Figer Space Telescope Science Institute

Outline n n The role of detectors in discovery. The state of the art in detectors. n n Keck/LGS/AO HST SOFIA Detectors and future Astronomy projects. n n n LSST SNAP JWST

The Role of Detectors

Detector Functions n n n Photometry Astrometry Spectoscopy Morphology Time Variability

Detector Types n n n 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 Hg. Cd. Te In. Sb In. Ga. As 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 n General-purpose orbiting astronomical telescope

HST

HST

HST

HST

HST

SOFIA: Stratospheric Observatory for Infrared Astronomy

LSST: Large Synoptic Survey Telescope n n What is the distribution of dark matter in the Universe? What is dark matter?

LSST

SNAP: Supernova Acceleration Probe n 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 290 K Transverse rear axis Side Gigacam location passive detector cooling combines Si & Hg. Cd. Te 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 n n Coalesce all sensors at one focal plane. n Imager sensors on the front. n 36 Hg. Cd. Te 2 kx 2 k 18 mm n 36 CCD 3. 5 kx 3. 5 k 10. 5 mm n Filters n 1 of 3 per Hg. Cd. Te n 4 of 6 per CCD n Spectrograph on the back with access ports through the focal plane. Exposure times of 300 s with four/eight exposures in CCDs/Hg. Cd. Te.

JWST: James Webb Space Telescope n n n 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 n n n 6. 5 m diameter primary mirror launch in 2013 orbit at L 2 four scientific instruments JWST deployment movie

IDTL: Independent Detector Testing Laboratory n n n 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 Mc. Candliss 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 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 Hg. Cd. Te • Nearly “ideal” characteristics. • Many vendors.

Properties of In. Ga. As: 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). Parameter Read Noise Comments / Notes < 10 e- with multiple reads Dark Current ~ 1 f. A/cm 2, @-100 C 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)

State of the Art: Si PIN Hybrid Arrays n Si PIN Hybrid QE Measures Data (from B. Pain, et. al. )

State of the Art: Si PIN Dark Current n n 0. 001 in e-/s/pixel for 10(18 mm pixel read noise H 2 RG-003 mm pixels) • 1 e- on reference pixels, Fowler-32, 100 k. Hz • 9 e- on science pixels, Fowler-32, 100 k. Hz well depth, 120, 000 e- • QE@ 1 mm • 24%@140 K • 28%@160 K • 33%@180 K • 38%@200 K • Crosstalk, 2 -3% • Persistence, <0. 3%

State of the Art: Si PIN Read Noise 10 e-

State of the Art: Hg. Cd. Te n n n Mature technology, although short-wave QE is recent development. Several vendors. Flight heritage n n NICMOS, 256 x 256, 2. 5 um cutoff. Hubble Wide Field Camera 3, H 1 RG, 2. 3 um cutoff. (Launch? ) Deep Impact MRI spectrometer, H 1 RG, 5 um cutoff. JWST NIRCam, NIRSpec, FGS, 2. 5 um and 5. 0 um cutoff. (Launch? )

State of the Art: Hg. Cd. Te Dark Current

State of the Art: Hg. Cd. Te Read Noise

State of the Art: In. Ga. As • Emerging technology. • Sensors Unlimited

State ofcontract the Art: SUI In. Ga. As n DARPA to develop 1280 x 1024 QE n n n In. Ga. As Array. Dark current goal of 2 n. A/cm 2. Read noise ~ 10 e- at video rates. Worth watching.

State of the Art: Photon Counting CCD n n n Emerging technology. Two (more? ) vendors. Low Light Level CCDs (L 3 CCDs), 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.