1. NIRCam: A 40 Megapixel Camera for JWST
Marcia Rieke
NIRCam P.I.

2. 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

3. 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

4. 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)

5. NIRCam Design Features
NIRCam images the 0.6 to 5mm ( mm prime) range
Dichroic used to split range into short ( mm) 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

6. Dichroic Provides Two Channels Per Module
Short wavelength channel
Long wavelength channel
Each module has two spectral wave bands SW:0.6mm - 2.3mm LW: 2.4 mm to 5 mm
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 A
Module B

7. NIRCam’s Role in JWST’s Science Themes
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
NIRCAM_X000
Inflation
Forming Atomic Nuclei
Recombination
First Galaxies
Reionoization
Clusters &
Morphology
Modern Universe
NIRCam
Quark Soup
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
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
young solar system
Kuiper Belt
Planets

8. NIRCam Science Requirements
5-s 50,000 secs
Detection of first light objects, studying the epoch of reionization requires:
Highest possible sensitivity – few nJy sensitivity is required.
Fields of view (~10 square arc minute) adequate for detecting rare first light sources in deep multi-color surveys.
A filter set capable of yielding ~4% rms photometric redshifts for >98% of the galaxies in a deep multi-color survey.
Observing the period of galaxy assembly requires in addition to above:
High spatial resolution for distinguishing shapes of galaxies at the sub-kpc scale (at the diffraction limit of a 6.5m telescope at 2µm).
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.
Number of Filters 6 5 4
Performance of adopted filter set 7 8
0.00
0.05
0.10
0.15
0.20
|Zin-Zout|/(1+Zin)
1<Z<2
2<Z<5
5<Z<10

9. 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

10. 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

11. 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

12. Field of View Layout

13. 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
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.
Spectra recorded by NIRCam
DHS at pupil
Fine phasing
After coarse phasing
Fully aligned

14. 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.
After correction
Max piston error=0.66 m
Rms=0.18 microns
Initial errors
Max piston error=19 m
Rms=5 microns
A prototype DHS was tested on Keck.

15. NIRCam Optical Train TodayV1 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 1 10 9 8 7 6 5 4 3 2 11 12 13 V3 V2
** These items + bench design changed from original proposal
ETU will have
Only one Module (B)
No LW Channel
No Coronagraphic capability

16. Coronagraph Concept Pupil Wheel Collimator Optics Camera NIRCam
Pickoff
Mirror
Telescope
Focal
Surface
Coronagraph Image
Masks
Coronagraph Wedge
JWST Telescope
Not to scale
NIRCam Optics
Field-of-View
FPA
Coronagraph Image Masks
Without Coronagraph Wedge
With Coronagraph Wedge
Filter
Calibration Source
Collimator
Optics
Camera
Wedge

17. Planet Observations
Simulation by John Krist

18. 100 Myr-Old, 2 MJup Planet

19. Shortwave Optical Path
SW FPA Flat
SW FPA
SW Camera Triplet
SW Fold Flat
Dichroic
Beamsplitter
Filter(s)
FFM
Collimator Triplet
POM
Lenses fabricated from either LiF, BaF2 or ZnSe.

20. Longwave Optical Path LW FPA Flat LW FPA LW Camera Triplet Filter(s)
Dichroic
Beamsplitter
FFM
Collimator Triplet
POM

21. WFE Performance

22. Transmission

23. Pathfinder - COL and SW Cam Singlets
ZnSe Singlet
Singlet with Vibe Fixture
LiF Singlet

24. Pathfinder DBS – Thermal Test to 105 K
White Chamber
Pathfinder
DBS
Thermal Strap
Interface Plate
Cold Table

25. SW Camera Assy – Thermal Vac Testing
White Chamber
Pathfinder DBS
SW Cam Assy
Thermal Straps
Interface Plate
Cold Table

26. 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

27. 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
Linear Actuators
Sensor & Target Assy

28. NIRCam Filter Wheels Filter/pupil wheels include extra cal features.
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
Filter/pupil wheels include extra cal features.
Shortwave FWA
Longwave Camera
Shortwave Camera

29. NIRCam Filters P

30. Pupil Wheel Calibration Source & Projectors
Pupil Alignment Pinhole
Projector
Flat Field Projector
Calibration Light Source

31. Grism 1: Horizontal Dispersion Grism 2: Vertical Dispersion
Grism Motivation
Primary technique for JWST coarse segment phasing uses 2 Dispersed Hartmann Sensors (prism arrays); reduces phase offsets from ~100 m to < 1m (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 ( nm RMS error)
Each grism covers all segments
Grisms in series with a LW filter
High long wavelengths gives large
capture range
Grism 1: Horizontal Dispersion
Grism 2: Vertical Dispersion

32. Spectra Positions on FPA of a Point Source at the Center of the Field
36.7 mm
4950 nm
4700 nm
3950 nm
3700 nm
3200 nm
2950 nm
LW FPA size 36.7 X 36.7 mm
Center Field Dispersion by Grism
Grism: Design
Spectra Positions on FPA of a Point Source at the Center of the Field
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 cross-section profile between long and short wavelength ends
Centroiding accuracy determines the minimum piston detection.
(s = 1/20 pixel is used)
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
F322W (partial), F356W (partial), F444W
±344 mm
Min = 3.5 mm, Max = 9.8 mm

33. 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 mm range
Three development detectors in test dewar.
Read Noise: median is 7.5 electrons in 1000 sec.
Well depth is nearly 2x the required 60,000 electrons.

34. Other Properties Excellent, too!
2mm flat fields. Flats show little wavelength dependence.
.025% of full well
Dark current floor
Differential
Cumulative
HgCdTe material is now produced by molecular beam epitaxy rather than liquid phase epitaxy which produces much more uniform and high quality material.

35. Detector Result: Using Reference Pixels
Reference pixels act like detector pixels electrically. They can be used to
Correct for drifts in the readout electronics (upper panel)
Correct for drifts due to temperature changes (lower panel)

36. Interpixel Capacitative Coupling
“Popcorn” Noise
Not Quite Perfect!
Time 
Interpixel Capacitative Coupling

37. Producing Mosaics
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.
Four arrays () are mounted to create a 4Kx4K mosaic ().

38. 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.

39. FPA Assembly Verification
Insert Plates
Black Epoxy Visible Through Plastic
FPA Baseplate

40. FPA Heater Assembly Verification
Mosaic Baseplate
Temperature Sensors
Titanium Struts
Heater

41. ETU Bench is finished!

42. Why Being PI Isn’t Fun!

43. 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.