COO Detector Activities

COO Detector Activities

Roger Smith

2010-01-27

Precision Projector

Current Themes2010-01-27COO Detector Activities

2

Galaxy shape measurement

for Weak Lensing

10ppm relative

photometry(ExoPlanets)

SpectroscopyWide field

ImagingNIR

Wavefront Sensing

0.5%SupernovaPhoto

metry

Delta Doped CCD demo

Precision Projector

Sponsors (indicated in black)

2010-01-27COO Detector Activities

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Weak LensingTransit

Photometry

NIRES,

DBSP-RedNIR WFS

SN Photometry

LBNL (DOE), JDEM (NASA)

LBNL (DOE)

Beichman (JPL DRDF+, NASA ROSES-SAT?)

Caltech

[ SUMIRE ?? ]

J.Johnson (CIT)

IRIS-OIWFS (TMT)

Keck1 TTF (NSF ATI?)

JPL DRDF … LBNL (DOE)

Palomar - PTF

Operational support (tapering off):

• Routine vacuum maintenance every 6 months.

• Cryotiger monitoring. Leak?

• Window contamination.


4

Delta Doped CCD demo on P60

• Collaboration with JPL.

• Dewar intended to become lab CCD test system after demo and be template for DBSP-R upgrade and maybe SPOTcam for J.Johnson.

• ∂ doped CCD production taking longer than anticipated.

• Dewar concept developed but not modeled.

…… Project suspended (postponed?)


5

ALN

CCD in picture frame

Idea 2.

Corner bolt threaded into frame

Metal frame presses on FG only where there is underlying Al Nitride

Alternate transition card location

Example slide from

conceptual design

IR Spectroscopy

• Extended effort to improve reliability of IR imager/guider for TripleSpec (Rahmer,Bonati,Hickey,Hale)

• Recently, support for NIRES commissioning by Gustavo.


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Optical Spectroscopy

• DBSP Red side upgrade in project definition phase:– Extend red QE.– Lower noise– Faster readout; modern controller.– Better spectrograph controls?

• Dewar design concept flows from DD-CCD project.

• Modular concept will also lead to lab capability, and serve as precursor for J.Johnson’s transit camera.


8

DBSP-R QE Scenario

• LBNL CCD QE > 90% in most of DBSP-Red range

• May use eng grade CCD from SWIFT


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250µm thickand ITO

Low order NIR WFS for TMT (IRIS)

• Three R-theta probes each feed a 1024x1024 area of H2RG. Only J+H band required but 2.5µm detector chosen for best read noise.

• Probe with brightest star is configured as 2x2 Shack-Hartman to measure focus+astigmatism, in addition to tip+tilt.


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Camera design2010-01-27COO Detector Activities

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Snout containing long cold baffle and cold JH filter

Mounting flange

Light tight detector housing, thermally isolated and controlled

Thermal links, tuned

Large getter container on cold head

Cryotiger

Readout mode for TMT-IRIS-OIWFS

• 1Kx1K FoV is only 2 arcsec; used for acquisition.

• Window progressively reduced to 4x4 pixels.

• Small window is nested within concurrently exposed larger window. Large window readout is concurrently exposed to recapture spot if lost.

• Developed sparse reset mode for ~100% duty cycle, and film strip mode for high frame rate tests.


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H2RG

2048

2048

Acquisition region ~ 1k × 1k

4×4 guide window 2 mas/pix

2 arcsec

14×14 recapture window

Noise vs speed measurements

• Multiple sampling beats noise down to ~2.7e- at 100 Hz guide rate for 4x4 window.


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Window size

Keck1 AO – TTF sensor

• Similar detector and readout scheme, but K band at 800-1000Hz instead of JH at 80-800 Hz.

• 100 mas/pixel; reimages full 120” AO FoV via dichroic for JH band science or annular mirror for K band science.

• Move ROI instead of probe.

• NSF ATI proposal submitted: Peter Wizinowich =PI; Thomas Stalcup = optical designer


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SNAP funded NIR detector work

• Studied noise in 1-3 hour exposures for 2.5µm HgCdTe. Sample up the ramp with CR rejection. Spatial and temporal noise compared.

• Investigating linearity and alleged “initial signal deficit” (in progress)

• H2RG power dissipation tests.

• Commissioning of Precision Projector.


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H2RG Spatial Noise for 91% Duty Cycle

0

1

2

3

4

5

6

100 1000 10000

Effective Exp Time (s)

Sp

ati

al N

ois

e (

e-)

no pixel masking

high DC 1/3 masked-off

high DC 2/3 masked-off

Spatial Noise v/s Effective Exp Time (91% Duty Cycle)Masking off high dark current pixels

• Masking process:• Create mean frame out of 60 images using 3-sigma

avsigclip, for 100s and 1000s exp times.• Subtract the two resulting mean frames: "mean_100-100.fits"• Select the 1/3 and 2/3 points from cumulative histograms.• Create masks replacing the masked-off pixels with out-of-

range values ("1" for good pixels).• Multiply the original Fowler-91% images sets by each mask.• Calculate noise statistics on delta images, using "out-of-

range" pixel value rejection on top of the usual outlier rejection (for CR).

SNAP CCD testing (pending)

• Tests of random flat fielding errors at the sub-percent level due to pixel area variations, using spot projection to validate previous inferences from fourier transforms of PRNU images.

• Validation our shrinking pixel hypothesis to explain the pixel to pixel correlations in shot noise, which throw off conversion gain calculations, and have mystified the CCD community since being reported by Mark Downing at the SPIE in Orlando in 2006


17

WL simulations (funded by NASA/JDEM)

• We have supplied detector models for Jason Rhodes to simulate the effect of detector behavior on systematic shape measurement errors:– Persistence, linearity, reciprocity failure, read noise, correct handling

of gain and quantization.

– JPL has supplied Inter-Pixel Capacitance model.

• The intent is to determine the sensitivity of WL errors to various detector effects, and thus determine requirements for calibration accuracy. This is being done as a function of plate to provide preliminary input to mission design selection for JDEM, SNAP, and possibly Euclid and HALO.

• This exercise is limited by our imperfect understanding of the detector behavior at the 0.1% level.


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Precision Projector (DRDF + SNAP funded)

• Emulation of 0.1% galaxy ellipticity measurement in lab to validate control of systematics for Weak Lensing experiments.

• The goal is to settle (inform?) the raging debate about how coarse the plate scale can be for various space missions doing WL.

• Offner Relay with λ/100, 18” primary is designed to re-image chrome on glass mask bearing 2000 to 5000 “objects” ~ 2.5pixel FWHM, at Strehl>99.6% over full area of H2RG or SNAP CCD, for f/8 or slower beams for λ > 500nm.

• Masks have 1µm minimum feature size and 50nm placement accuracy.

• Mask stage provides 6 axis motion in 50nm increments.


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Spot diagrams, encircled energy 2010-01-27COO Detector Activities

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Progress to date2010-01-27COO Detector Activities

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Primary mirror assembled in sling mount

Secondary mirror procured. Mount is in shop.

Masks procured and sample measured with electron microscope; 6 axis mask stage and integrating sphere in hand.

Bench thermal control system built and tested.

Exoplanet Transits

For John Johnson, Palomar instrument is in planning.

For Chas Beichman, testing in support of ASTrO proposal later this year ($200M explorer class mission):

• First cut:– Funded ($17K CIT, $13K JPL) to demonstrate plausibility of <100ppm

photometry of a bright star relative to an ensemble of similarly bright stars, using Teledyne H2RG.

– Will image a single pinhole through a lenslet array to create several hundred artificial stars with a common light source.

• Next steps:– ROSES-TDEM proposal rejected, so JPL internal funds being sought

for tests with Precision Projector in which PSF is well controlled and small pointing changes can be simulated.


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Documents

COO Detector Activities