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NIRCam: A 40 Megapixel Camera for JWST Marcia Rieke NIRCam P.I. A Competitor 39 million pixels • The H2D-39 uses a 39 megapixel sensor that is more than twice the physical size of today’s 35mm sensor…. • You only need to spend $33K to get nearly as many pixels as NIRCam So what do you get for your extra $100M for a NIRCam? -- a camera that works from 0.6 to 5 microns, not just from 0.36 microns to 0.8 microns and which can survive the space environment 2 NIRCam Partners • Science Team from Arizona, JPL, Rochester Institute of Technology, Canada, Hawaii, Switzerland, Spitzer Science Center, NASA Ames • Lockheed-Martin in Palo Alto, CA, is responsible for design and construction of the most of the instrument • Arizona is procuring detectors from Teledyne Imaging Systems in Camarillo, CA, and will deliver them to L-M after characterization and assembly into mosaics • Space Telescope Science Institute will operate NIRCam after launch: Current NIRCam Team includes Jay Anderson, Massimo Robberto, and Kailash Sahu 3 Full Science Team Science Theme Leads Chas Beichman (Debris Disks &Planet.Systems) JPL Daniel Eisenstein (Extragalactic) University of Arizona Michael Meyer (Star Formation) University of Arizona Team Members Stefi Baum Roch. Institue of Tech Simon Lilly ETH Laura Ferrarese HIA/DAO Peter Martin University of Toronto René Doyon Université de Montréal Don McCarthy (EPO Lead) U of Arizona Alan Dressler Carnegie George Rieke University of Arizona Tom Greene NASA Ames Tom Roellig NASA Ames Don Hall University of Hawaii John Stauffer Spitzer Science Center Klaus Hodapp University of Hawaii John Trauger JPL Scott Horner Lockheed Martin ATCr Erick Young University of Arizona Doug Johnstone HIA/DAO Associated scientists: Doug Kelly, John Stansberry, Christopher Willmer, Karl Misselt, Chad Engelbracht (Az), John Krist (JPL) 4 NIRCam Design Features • NIRCam images the 0.6 to 5mm (1.7 - 5mm prime) range – Dichroic used to split range into short (0.6-2.3mm) and long (2.4-5mm) sections – Nyquist sampling at 2 and 4mm – 2.2 arc min x 4.4 arc min total field of view seen in two colors (40 MPixels) – Coronagraphic capability for both short and long wavelengths • NIRCam is the wavefront sensor – Must be fully redundant – Dual filter/pupil wheels to accommodate WFS hardware – Pupil imaging lens to check optical alignment 5 Dichroic Provides Two Channels Per Module Short wavelength channel Long wavelength channel •The majority of NIRCam exposure time will be used for deep survey observations over the 7 wide band filters •Survey efficiency is increased by taking observations of the same fields in long wave and short wave bands simultaneously Module B SW:0.6mm - 2.3mm LW: 2.4 mm to 5 mm Module A Each module has two spectral wave bands 6 NIRCam’s Role in JWST’s Science Themes NIRCam NIRCAM_X000 Modern Universe Clusters & Morphology Reionoization First Galaxies Recombination Forming Atomic Nuclei Inflation Quark Soup The First Light in the Universe: Discovering the first galaxies, Reionization NIRCam executes deep surveys to find and categorize objects. Period of Galaxy Assembly: Establishing the Hubble sequence, Growth of galaxy clusters NIRCam provides details on shapes and colors of galaxies, identifies young clusters Stars and Stellar Systems: Physics of the IMF, Structure of pre-stellar cores, Emerging from the dust cocoon NIRCam measures colors and numbers of stars in clusters, measure extinction profiles in dense clouds young solar system Kuiper Belt Planets Planetary Systems and the Conditions for Life: Disks from birth to maturity, Survey of KBOs, Planets around nearby stars NIRCam and its coronagraph image and characterize disks and planets, classifies surface properties of KBOs 7 1000 NIRCam Science Requirements – Highest possible sensitivity – few nJy sensitivity is required. 100 nJy • Detection of first light objects, studying the epoch of reionization requires: 5-s 50,000 secs 10 1 0.1 0.5 1.5 – High spatial resolution for distinguishing shapes of galaxies at the sub-kpc scale (at the diffraction limit of a 6.5m telescope at 2µm). Space (HST or SPITZER) JWST z=5.0 z=10.1 Performance of adopted filter set Number of Filters 4 5 6 4 Number of Filters • Observing the period of galaxy assembly requires in addition to above: 4.5 Point source sensitivities for 50,000 sec exposures and 5:1 signal-to-noise ratio. The z=10 galaxy has M=4x108M and the z=5 galaxy has M=4x109M. 5 6 7 4 Number of Filters – A filter set capable of yielding ~4% rms photometric redshifts for >98% of the galaxies in a deep multi-color survey. 3.5 l( mm) Ground (Keck/VLT) – Fields of view (~10 square arc minute) adequate for detecting rare first light sources in deep multi-color surveys. 2.5 5 6 7 8 0.00 1<Z<2 0.05 2<Z<5 0.10 |Zin-Zout|/(1+Zin) 8 5<Z<10 0.15 0.20 NIRCam Science Requirements cont’d • Stars and Stellar Systems: – High sensitivity especially at l>3mm – Fields of view matched to sizes of star clusters ( > 2 arc minutes) – High dynamic range to match range of brightnesses in star clusters – Intermediate and narrow band filters for dereddening, disk diagnostics, and jet studies – High spatial resolution for testing jet morphologies • Planetary systems and conditions for life requires: – Coronagraph coupled to both broad band and intermediate band filters – Broad band and intermediate band filters for diagnosing disk compositions and planetary surfaces 9 Derived Requirements • nJy (10-35 W/m2/Hz) sensitivity – Detectors with read noise < 9 e-, Idk<0.01 e/sec QE>80% – Focal plane electronics with noise < 2.5e- so detector performance is not degraded – High throughput instrument: 70% for optics, 85% for filters • At least 7 broadband filters for redshift estimates • Large Field of View – Dichroics to double effective FOV – Large format detector arrays • Large well-depth on detectors • High spatial resolution – Nyquist sampling at 2mm and 4mm 10 Derived Requirements cont’d • Selection of intermediate and narrowband filters – 8 R~10 filters needed to classify ices, cool stars – At least 4 R~100 filters for key jet emission lines (want higher spatial resolution than Canadian tunable filters) • Coronagraph required in all modules – Coronagraph most important at long wavelengths – Coronagraphic field must not reduce survey FOV • Need fluxes calibrated to 2% – Requires gain stability on week time scales – Requires on-orbit calibration plan using on stars 11 Field of View Layout 12 NIRCam as Wavefront Sensor: Initial Capture and Alignment •Telescope focus sweep •Segment ID and Search •Global alignment •Image stacking •Coarse phasing •Fine phasing •Multi-field fine phasing. First Light After segment capture Coarse phasing w/DHS • • Spectra recorded by NIRCam DHS at pupil Fine phasing • After coarse phasing Fully aligned NIRCam provides the imaging data needed for wavefront sensing. Two grisms have been added to the long wavelength channel to extend the segment capture range during coarse phasing and to provide an alternative to the Dispersed Hartmann Sensor (DHS) Entire wavefront sensing and control process demonstrated using prototypes on the Keck telescope and on the Ball Testbed Telescope. 13 Coarse Phasing with the Dispersed Hartmann Sensor DHS is collection of grisms and wedges that are placed in the NIRCam pupil wheel. Every segment pair is covered by one grism so coarse phasing consists of measuring spectra to determine the offset in the focus direction between segments. Process is robust even if a segment is missing. Initial errors Max piston error=19 mm Rms=5 microns After correction Max piston error=0.66 mm Rms=0.18 microns A prototype DHS was tested on Keck. 14 NIRCam Optical Train Today 11 3 10 12 4 5 9 2 6 1 13 7 1 Pick-off Mirror assembly ** 2 Coronagraph 3 First Fold Mirror 4 Collimator lens group 5 Dichroic Beamsplitter 6 Longwave Filter Wheel Assembly 7 Longwave Camera lens group 8 Longwave Focal Plane 9 Shortwave Filter Wheel Assembly 10 Shortwave Camera lens group 11 Shortwave Fold Mirror 12 Pupil Imaging Lens ** 13 Shortwave Focal Plane ** These items + bench design changed from original proposal 8 • ETU will have – Only one Module (B) – No LW Channel – No Coronagraphic capability 15 Coronagraph Concept Coronagraph Image Masks JWST Telescope NIRCam Pickoff Mirror Collimator Optics Telescope Focal Surface Camera Optics Pupil Wheel Filter Wheel Coronagraph Wedge Not to scale Not to scale Coronagraph Image Masks FPA NIRCam Optics Field-of-View Without Coronagraph Wedge Calibration Source FPA Collimator Optics With Coronagraph Wedge Wedge 16 Camera Optics Planet Observations Simulation by John Krist 17 100 Myr-Old, 2 MJup Planet 18 Shortwave Optical Path SW FPA Flat SW Camera Triplet SW FPA SW Fold Flat Dichroic Beamsplitter Filter(s) 6 17 :0 5 1: MM 50 50 0. e: al c S FFM 125.00 o OTE 03/02/04 POM Scale: 0.20 Lenses fabricated from either LiF, BaF2 or ZnSe. MM Collimator Triplet 10-Mar-05 m Ca IR no Mo OT E 03 / 02 04 / 19 .0 0 Longwave Optical Path LW FPA Flat LW FPA LW Camera Triplet 09 1: :0 17 Filter(s) Dichroic Beamsplitter MM . 50 50 0. e: al Sc FFM Mono OTE 03/02/04 Collimator Triplet 4 POM Scale: m 0.21 Ca NI R M /0 02 / 03MM 119.05 E OT o on 10-Mar-05 20 00 -M 10 WFE Performance Predicted WFE through SW Filters 80 70 Requirement (nm rms) 50 Prediction (nm rms) 40 30 20 10 0 2 N N N N M M M W 0W 90W 0W 50W 0W 08 64 87 12 62 82 10 7 1 00 1 1 1 2 1 1 2 5 0 0 1 1 2 F F F F F F F F F F F F F1 Predicted WFE through LW Filters 200 150 Requirement (nm rms) 100 Prediction (nm rms) 50 F4 70 N F4 60 M F4 44 W F4 30 M F4 05 N F3 56 W F3 35 M F3 00 M 0 F2 70 W WFE WFE 60 21 Transmission Transmission vs Wavelength 100% 90% Requirement: > 66% 70% @ 1.1 microns micron 80% 70% T 60% SW LW 50% 40% 30% 20% 10% 0% 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Wavelength (microns) 22 5 Pathfinder - COL and SW Cam Singlets ZnSe Singlet Singlet with Vibe Fixture LiF Singlet 23 Pathfinder DBS – Thermal Test to 105 K White Chamber Pathfinder DBS Thermal Strap Interface Plate Cold Table 24 SW Camera Assy – Thermal Vac Testing White Chamber Pathfinder DBS SW Cam Assy Thermal Straps Interface Plate Cold Table 25 Pupil Imaging Lens (“The PIL”) A pupil imaging lens was added to NIRCam to assist with aligning NIRCam to the telescope and to provide pupil data to the wavefront sensing algorithm. Qual unit pupil imaging lens 26 FAM Role in NIRCam The NIRCam Focus and Alignment Mechanism (FAM) contains the Pick-Off Mirror (POM), the first element in the NIRCam optical train. It has the capability to position the POM in 3 degrees of freedom; focus, tip, and tilt. POM Assembly Sensor & Target Assy Linear Actuators 27 NIRCam Filter Wheels • Both the long and the short wave channels have dual-filter wheel assemblies • The first wheel is located at the NIRCam pupil and is referred to as the pupil wheel • The second wheel is referred to as the filter wheel Longwave FWA Dichroic Beam Splitter Shortwave FWA Filter/pupil wheels include extra cal features. Longwave Camera Shortwave Camera 28 NIRCam Filters 4 F150W2 3.5 F322W2 3 F164N F187N F212N 2.5 F405N F418N F466N F470N PP P P 2 PP F225N 1.5 F140M PF182MF210M F162M 1 0.5 F323N F150W F115W F090W F070W F250M F300M F200W F277W F460M F360M F410MF430M F335M F356W F480M F444W 0 0.5 1.5 2.5 3.5 4.5 5.5 l(mm) 29 Pupil Wheel Calibration Source & Projectors Pupil Alignment Pinhole Projector Flat Field Projector Calibration Light Source 30 • Primary technique for JWST coarse segment phasing uses 2 Dispersed Hartmann Sensors (prism arrays); reduces phase offsets from ~100 mm to < 1mm (PSF is sensitive to even larger errors) – Each prism covers 2 segments; fringes produced when segment offsets cause pos / neg interference as function of wavelength – Has been successfully demonstrated on Keck • 2 identical grisms (rotated 90 deg) are being added as a backup for coarse phasing technique, but they will also enable science – Dispersed Fringe Sensing: tilt of dispersed fringe yields segment piston – Also validated on Keck (90-142 nm RMS error) – Each grism covers all segments – Grisms in series with a LW filter – High dispersion @ long wavelengths gives large capture range Grism 1: Horizontal Dispersion 31 Grism 2: Vertical Dispersion Grism Motivation Grism: Design • 4950 nm 4700 nm Y=0.000 • 65 gv/mm design meets WFS requirements Maximum piston listed is from the red-spectral DFS algorithm with short wavelength end starts from center of spectral range Minimum piston listed comes from fringe tilt detected by using differential centroid of the crosssection profile between long and short wavelength ends – Centroiding accuracy determines the minimum piston detection. (s = 1/20 pixel is used) 15:49:04 • Spectra Positions on FPA of a Point Source at the Center of the Field 3950 nm 3700 nm 3200 nm 2950 nm 36.7 mm LW FPA size 36.7 X 36.7 mm Center Field Dispersion by Grism 12.9 SURFACE 45 MM 09-Feb-07 NIRCam Mono OTE 03/02/04 Grism Wavelength Range NIRCam Filters Maximum Piston Minimum Piston Grism Thickness 65.0 gv/mm 3.30 – 5.0 mm F322W (partial), F356W, F444W ±291 mm ±0.12 mm Min = 3.3 mm, Max = 8.5 mm 75.0 gv/mm 3.30 – 5.0 mm F322W (partial), F356W (partial), F444W ±344 mm ±0.12 mm Min = 3.5 mm, Max = 9.8 mm 32 Near IR Detectors • Three instruments (NIRCam, NIRSpec, FGS/TFI) use the same detectors. NIRCam uses two flavors of HgCdTe, 2.5mm and 5.2mm cut-off material. • Basic format is 2040x2040 with 4 reference pixels around the periphery • Performance is great – dark current at 37K is ~.005 e/sec, QE is > 80% over the full 0.6 5mm range Three development detectors in test dewar. 180000 3.5E+06 2.5E+06 2.0E+06 140000 120000 Electrons 3.0E+06 No. of pixels 160000 Read Noise: median is 7.5 electrons in 1000 sec. 1.5E+06 100000 80000 60000 Well depth is nearly 2x the required 60,000 electrons. 1.0E+06 40000 5.0E+05 20000 0 0.0E+00 0 5 10 15 20 Read noise in 1000 secs (electrons) 25 30 0 100 200 300 Time(secs) 33 400 500 Other Properties Excellent, too! 14 12 .025% of full well 10 ADUs 8 Cumulative 6 4 2 0 Dark current floor -2 0 20 40 60 Time (sec) 2mm flat Differential fields. Flats show little wavelength dependence. 80 100 120 • HgCdTe material is now produced by molecular beam epitaxy rather than liquid phase epitaxy which produces much more uniform and high quality material. 0.5 1.0 34 16300 Detector Result: Using Reference Pixels 16250 16200 ADU_ 16150 16100 16050 16000 15950 15900 0 500 1000 1500 2000 2500 Sample No. (~10.6sec/sample) C034 Cooling Ref pixels Detector pixel 25000 1) Correct for drifts in the readout electronics (upper panel) _ DC Level in ADU _ Reference pixels act like detector pixels electrically. They can be used to 24000 23000 22000 21000 20000 30 40 50 60 70 80 T(K) Ref pixel Detector pixel Fit 90 2) Correct for drifts due to temperature changes (lower panel) 35 “Popcorn” Noise Not Quite Perfect! Time Interpixel Capacitative Coupling Reset Anomaly 19500 19000 ADU _ 18500 18000 17500 17000 16500 0 200 400 600 800 1000 Time (secs) 998 1163 1008 1783 36 Producing Mosaics Four arrays () are mounted to create a 4Kx4K mosaic (). • After SCAs (sensor chip assemblies) are produced at Teledyne, they will be mounted with minimal gaps to produce a 4Kx4K mosaic for NIRCam’s short wavelength arm. • Location of SCAs within the mosaic will be verified by using a precise measuring microscope which can measure the location of a surface to better than 10 microns in all three coordinates. • Mosaicing done at Steward. 37 FPA Mock-up Assembled FPA less SCAs and the mask. All parts can be machined in Tucson, most on campus. Mask to cover gaps and bond wires. Ti flexure. 38 FPA Assembly Verification Insert Plates Black Epoxy Visible Through Plastic FPA Baseplate 39 FPA Heater Assembly Verification Mosaic Baseplate Temperature Sensors Titanium Struts Heater 40 ETU Bench is finished! 41 Why Being PI Isn’t Fun! 42 NIRCam is on its way! • Much of the NIRCam Engineering Test Unit hardware has been delivered to Palo Alto with the ETU to be delivered to Goddard early next year. • Collection of detector calibration data in progress. • Some flight hardware is also already in hand. The flight unit is to be delivered in the spring of 2010. 43