instrument design/development overview and system performance
DESCRIPTION
Instrument Design/Development Overview and System Performance. PACS Instrument Overview Poglitsch MPE. Instrument Concept. Focal Plane Footprint. Imaging photometry two bands simultaneously (60-85 or 85-130 µm and 130-210 µm) with dichroic beam splitter - PowerPoint PPT PresentationTRANSCRIPT
PACS Instrument Overview 1
PACS IHDR 12/13 Nov 2003
Instrument Design/Development Overview and
System Performance
PACS Instrument Overview
A. Poglitsch
MPE
PACS Instrument Overview 2
PACS IHDR 12/13 Nov 2003
Instrument Concept• Imaging photometry
– two bands simultaneously (60-85 or 85-130 µm and 130-210 µm) with dichroic beam splitter
– two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling)
– point source detection limit ~3 mJy (5, 1h)
• Integral field line spectroscopy
– range 57 - 210 µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500)
– two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed)
– point source detection limit 3…10 x10-18 W/m2 (5, 1h)
Focal Plane Footprint
32 x 16 pixels6.4” x 6.4”
64 x 32 pixels3.2” x 3.2”
PACS Instrument Overview 3
PACS IHDR 12/13 Nov 2003
Observing Modes
• Combinations of instrument modes and satellite pointing modes
• Instrument modes:– dual-band photometry– single-band photometry– line spectroscopy
• observation of individual lines
– range spectroscopy• observation of extended wavelength ranges
• Pointing modes:– stare/raster/line scan– with/without nodding
PACS Instrument Overview 4
PACS IHDR 12/13 Nov 2003
CEA
BOL/BAU
BlueBol BAU
RedBol BAU
Warm Interconnecting Harness
Instrument Overview and Subsystem Responsibilities
DPU nominal
DPU redundant
IFSI-ROME
DEC/MEC 2
MEC I/F-Module Redundant
DSP Module Redundant
RedDEC Module
Base/PSU Redundant
CSL-Liege
BOL/COOL
BOL 1 Module
BOL 2 Module
Cooler Control
CEA
FPU Cold FocalPlaneUnit
KT/MPE
BlueGe:GaArray &CRE
MPE/ASTEQ/IMEC
BlueBolArray &Read-out
CEA
RedBolArray &Read-out
CEA
RedGe:GaArray &CRE
MPE/ASTEQ/IMEC
0.3K Cooler CEA
Grating Assy CSL-Liege
Chopper Assy MPIA
2FilterWheels KT
2CalSources KT
SPU nominal
SPU redundant
IAC-Tenerife/TU-Wien
IAC-Tenerife/TU-Wien
CSL-Liege
DEC/MEC 1
MEC I/F-Module
DSP Module
BlueDEC Module
Base/PSU
PACS Instrument Overview 5
PACS IHDR 12/13 Nov 2003
FPU/Optics
FPU Cold FocalPlaneUnit
KT/MPE
BlueGe:GaArray &CRE
MPE/ASTEQ/IMEC
BlueBolArray &Read-out
CEA
RedBolArray &Read-out
CEA
RedGe:GaArray &CRE
MPE/ASTEQ/IMEC
0.3K Cooler CEA
Grating Assy CSL-Liege
Chopper Assy MPIA
2 FilterWheels KT
2 Calibrators KT
Chopper
sGeGaDetectorRed Spectrometer
Blue Bolometer
Red Bolometer
Calibrator I and II
0.3 K Cooler
Filter Wheel I
Filter Wheel II
Grating
GeGa DetectorBlue Spectrometer
Encoder
Grating Drive
Entrance Optics
PhotometerOptics
Calibrator Optics
SlicerOptics
SpectrometerOptics
PACS Instrument Overview 6
PACS IHDR 12/13 Nov 2003
Design/Development Status of Technically Critical Components
• Optics• FPU/Structure• Photoconductors, CRE• Bolometers• Chopper• Grating assembly• Warm electronics
PACS Instrument Overview 7
PACS IHDR 12/13 Nov 2003
Optics
• Design of FPU optics unchanged, manufacturing of mirrors complete, filters partly delivered
• Alignment of QM optics in progress, specs fulfilled so far
• Analyses (geometrical-optical, diffraction) done; to be complemented by measurements with IL tests/ calibration
• Baffle design and manufacture for QM FPU finished; optimisation for FM in progress
• Calibration sources manufactured and tested
Details from N. Geis / D. Kampf
PACS Instrument Overview 8
PACS IHDR 12/13 Nov 2003
• Detailed design of FPU structure finished, but thermal strap interface issues open.
• Manufacture of QM structure complete, manufacture of FM started
• Cryo-vibration performed on STM– Photometer STM including cooler and Focal Plane
Assembly– Grating STM, including new launch lock (without motor)– One of two filter wheels– Both photoconductor arrays (partly dummies)– Dummy chopper
Details from J. Schubert and D. Kampf
FPU Status
PACS Instrument Overview 9
PACS IHDR 12/13 Nov 2003
9
PACS Instrument Overview 10
PACS IHDR 12/13 Nov 2003
Photoconductor Arrays
• All QM detector “sixpacks” (2 high-stress, 2 low-stress) delivered to MPE / MPIA for testing
• Tests of all low-stress modules finished at MPIA, all high-stress modules + a few low-stress modules tested at MPE after repair at ASTEQ
• QM schedule tight (critical path) – see below– Integration of modules with
housing + filters has to start• FM schedule driven by
– CREs: FM wafers (CRE v06) processed, AIT in progress
– New contact (?) problem Details from H. Richter
PACS Instrument Overview 11
PACS IHDR 12/13 Nov 2003
Responsivity of modules in Sixpack1_MPIA(left: before vibration, right: after vibration)
A/W
“Blue” Ge:Ga QM Detector Test Results
Sixpack2_MPIA
NEP ~ 5x Herschel/PACS BLIP (with QM CRE)
PACS Instrument Overview 12
PACS IHDR 12/13 Nov 2003
“Red” Ge:Ga QM Detector Test Results
• NEP (even with QM CRE) approaching advertised value• Some “weak” pixels, varying from cooldown to cooldown• Few “dead” pixels (open channels)
QM7: responsivity at T=1.9K, C=0.52pF, t=0.25s
P = 4.8e-15 W
0
100
200
300
400
500
600
0 20 40 60 80 100
bias [mV]
r [A
/W]
detector1
detector 2
detector 3
detector 4
detector 5
detector 6
detector 7
detector 8
detector 9
detector 10
detector 11
detector 12
detector 13
detector 14
detector 15
detector 16
QM7: NEP at T=1.9K, C=0.52pF, t=0.25s
P = 4.8e-15 W
1E-17
1E-16
1E-15
0 20 40 60 80 100bias [mV]
NE
P [
W /
Hz]
detector1
detector 2
detector 3
detector 4
detector 5
detector 6
detector 7
detector 8
detector 9
detector 10
detector 11
detector 12
detector 13
detector 14
detector 15
detector 16
BLIPHerschel/PACS
FM14, FM12, FM11QM12, QM11, QM8
FM11, QM7, QM9, QM3QM12, QM11, QM8
Details from U. Grözinger
PACS Instrument Overview 13
PACS IHDR 12/13 Nov 2003
Cryogenic Read-Out Electronics
• CQM run (v05)– Integrated in QM modules + test modules– Tested extensively – current noise too high (at least for
low-stress array – by factor ~5)– CQM not suitable for FS, but useful for QM ILT
• FM run (v06)– Significant design modifications (3 variations
implemented)– Wafers processed– First tests very promising in terms of noise
performance– Delivery starting Nov/Dec ’03
• FS run my become necessary to reach all specs– should come in time to allow allow detector swapping
Details from P. Merken
PACS Instrument Overview 14
PACS IHDR 12/13 Nov 2003
QM CRE (v05) Performance
• Linearity : <3% non-linearity over >2V
• Cross talk between channels: <1% full range
• Linearity, cross talkmeet requirements– with blind channel
subtraction
• Noise too high by factor ~514
Raw ramp
Blind channel subtracted
PACS Instrument Overview 15
PACS IHDR 12/13 Nov 2003
Bolometer/Readout Development
• QM blue focal plane array mounted at LETI
• The working arrays showed a very large responsivity (good!)
• The working arrays show very large noise and very slow response of the clocks, due to high contact resistance (~MΩ) at the 2K Buffer Unit level (known error in QM buffer run causing poor indium bumps hybridization)
• A new blue focal plane is being mounted with FM Buffer Unit to be used in the CQM
More from L. Rodriguez et al.
Blue Focal Plane
PACS Instrument Overview 16
PACS IHDR 12/13 Nov 2003
Bolometer/Readout DevelopmentRed Focal Plane• A red focal plane with two sub arrays has been assembled• No tests because of known Buffer Unit problems. Decision to
replace the BU right away• This detector is now completed and under test• The measured noise levels are good everywhere except for a few
pixels on each array• Spectral response measured with FTS; absorption ~80% in band50 100 150 200 250 300 350 400 450 500 550 600
0
2
4
6
8
10
12
14
16
Wavelength in microns
ReferenceRed array
50 100 150 200 250 300 350 400 450 500 550 6000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Wavelength in microns
Ab
sorp
tion
measured
calculated
PACS band
PACS Instrument Overview 17
PACS IHDR 12/13 Nov 2003
Bolometer Performance Tests
• Detector bandwidth measured ~4 - 5 Hz
• “1/f” noise “knee”/ stability measurement: no significantincrease downto 0.05 Hz
requirement
goal requirement
= 10-16 W/√Hz (requirement)^
PACS Instrument Overview 18
PACS IHDR 12/13 Nov 2003
3He Sorption Cooler Development
0
1 10-5
2 10-5
3 10-5
4 10-5
5 10-5
6 10-5
0 50 100 150 200 250
y = 4,11371e-06 + 2,09004e-07x R= 1
1/ti
me
(s
-1)
Applied load (µW)
CQM SPIRE - Autonomy tests Nominal conditions - L0 = 1.7 K / L1 = 4 K
Theoretical curve
0 5 10-5 0,0001 0,00015 0,0002 0,00025
y = 5,3392e-06 + 0,22163x R= 0,99898
Applied load (µW)
Theoretical curve
CQM PACS - Autonomy tests Nominal conditions - L0 = 1.7 K / L1 = 4 K
First test with 10 µWapplied load:
35 hours @ 291 mK
250
300
350
0 20 40 60 80 100
HCR#1 - horizontalHCR#1 - right side upHCR#1 - upside downHCR#2 - horizontalHCR#2 - right side upHCR#2 - upside downHCR#3 - horizontalHCR#3 - right side upHCR#3 - upside down
Tem
pe
ratu
re (
mK
)
Cooling power (µW)
CQM PACS - Thermal tests June - August 2003 Comparison HCR #1 HCR#2 and HCR#3Level 1 (titanium frame) : 2 KLevel 0 (cryostat cold plate) : Å 1.6 K
Note : HCR#3/upside downLevel 0 at1.66 K
• extra load of 8-10 µW identified (potential heat switch problem)• 10% undercharged Details from L. Duband
PACS Instrument Overview 19
PACS IHDR 12/13 Nov 2003
Chopper
• QM delivered for integration in FPU
• Performance demonstrated• Scratches on mirror
– t.b. avoided with FM
• Tests of chopper control with DECMEC and LM concluded
• Adjustment of control parameters for QM only during IL tests
Details from R. Hofferbert
19
PACS Instrument Overview 20
PACS IHDR 12/13 Nov 2003
Grating Assembly
• Grating Mechanism/Drive– STM including new launch-lock (without actuator) passed
cryo-vibration test• STM mechanism shows better dynamic characteristics than
before vibration. The apparent "friction" torque is roughly reduced by a factor 2 to 3.
• Bearings qualified: no movement noise or hard point over the useful stroke
– Transformer for Inductosyn position readout shows excellent cold performance. Dissipation measured 1.5 mW
– CQM delivered to CSL• Few minor NCRs, one major (connectors swapped)• Functional/performance tests performed • FUB QM transformers integrated in QM ILT• Launch-lock actuator will be integrated• Loose spring washer, shaft-to-bearing coupling part has moved
in cryo-vibration test
PACS Instrument Overview 21
PACS IHDR 12/13 Nov 2003
• Diffraction grating– QM grating fully
characterised– Test of grating
constantand grating periodicity: all parameters inor near spec(acceptedby optics SE)
Grating Assembly
PACS Instrument Overview 22
PACS IHDR 12/13 Nov 2003Warm Electronics: AVM Instrument Level
Tests
PACS Instrument Overview 23
PACS IHDR 12/13 Nov 2003
Status of AVM Tests (1)
• CDMS simulator upgrade to V2.4– Has solved some counter overrun problem and the time
bug (now we have correct TAI)– Burst mode for PACS implemented
• DPU OBSW: several updates– Mainly for 1355 link loss investigation– But solving only the other known problems (EEPROM,
jump to application software)– Bug found in DPU ISR routine (by comparison with
DECMEC)– New problem with 1553 interface discovered. HW? SW?
DPU problems not solved in >1 year – start of ILT at risk!
• DECMEC OBSW is pretty stable
PACS Instrument Overview 24
PACS IHDR 12/13 Nov 2003
Status of AVM Tests (2)
• AVM SPU– Identified HW problem fixed – A small problem related to the SPU-DMC 1355 link initial
self-test has been found, but apparently this is inherent to the SMCS chip. Either the SPU_SUSW and/or the user manual need to be updated.
• SPU HLSW upgraded to version 6.0– It contains some performance improvements both with
respect to CPU work load and compression ratio– Parallel mode will require small update– Goal for CQM is to develop, in parallel, an improved
strategy (noise estimate from averaged ramp per pixel) and test it
• Down-link of “near-raw” data to allow ramp modeling / glitch removal on ground
• CPU load down presently still too high, optimisation in progress
PACS Instrument Overview 25
PACS IHDR 12/13 Nov 2003
SPU Ground Simulator
Ground simulation of SPU code useful for several reasons:
• Use PACS “raw data” transmission mode to redo, on ground, the same operations as performed by the on-board S/W
• Dispose of a test bed to try out new compression algorithms before they are up-linked and used by on-board S/W
• Subject PACS simulator data to same artifacts, i.e. compression and reduction, as on-board obtaineddata
• New version of on-board SPU has been “grounded” in less than five minutes work
PACS Instrument Overview 26
PACS IHDR 12/13 Nov 2003
Instrument Performance
• Instrument Requirements– Photometer– Spectrometer
• Instrument Model– Optical performance– Sensitivity budget
• optical transmission• background• detector performance
PACS Instrument Overview 27
PACS IHDR 12/13 Nov 2003
Photometer Performance Requirements
• Image quality– blur: telescope limited– distortion: ±1 pixel; alignment: <1/3 pixel
• Sensitivity (point source detection)– requirement: 5 mJy (5), 1h of integration– goal: 3 mJy (5), 1h of integration
• Dynamic range– detection from 3 mJy to >1000 Jy (goal: 3000 Jy) – contrast of up to 1:500 in one field
• Post-detection bandwidth– requirement: 0.5 - 5 Hz– goal: 0.05 - 5 Hz
PACS Instrument Overview 28
PACS IHDR 12/13 Nov 2003
Spectrometer Performance Requirements
• Image quality– blur: telescope limited– distortion: ±1 pixel; alignment: <1/4 pixel
• Sensitivity (point source detection)– requirement: 3x10-18 W/Hz1/2 (5), 1h of integration– goal: 2x10-18 W/Hz1/2 (5), 1h of integration
• Dynamic range– detection from ~1x10-18 W to >10-13 W– contrast of up to 1:100 in one field
• Post-detection bandwidth– requirement: 5 Hz– goal: 10 Hz
PACS Instrument Overview 29
PACS IHDR 12/13 Nov 2003
Optical Performance
• Optical design / implementation fulfills requirements regarding– field of view– spatial sampling– distortion– geometrical spot sizes (Strehl ratio)– alignment– internal calibration capability– chopping– spectral coverage and resolution– transmission / diffraction losses
Details from N. Geis / D. Kampf
PACS Instrument Overview 30
PACS IHDR 12/13 Nov 2003
(a) Values for the photometry modes from 60-85 or 85-130 µm / 130-210 µm, respectively.
(b) The formal transmission of >1 takes into account the acceptance solid angle of the photoconductor light cones / bolometer baffles which differs from the beam solid angle.
Parameters of PACS Instrument Model(Present estimate, partly based on
measurements)
PACS Instrument Overview 31
PACS IHDR 12/13 Nov 2003
Grating diffraction order efficiency
Resolving power
Telescope efficiency(main beam)
Main beam / pixel coupling
Spectrometer Performance
PACS Instrument Overview 32
PACS IHDR 12/13 Nov 2003
Detective quantum efficiency
Background power [W] BLIP NEP [W/Hz1/2]
on-array chopping
off-positionchopping
Sensitivity [W/m2](5, 1 hour)
Spectrometer Performance
Requirement
PACS Instrument Overview 33
PACS IHDR 12/13 Nov 2003
Photometer Sensitivity
• Assumed detector QE: 80% (based on FTS measurements)
• Assumed detector NEP: 10-16 W/Hz1/2 (based on electrical noise and responsivity measurements)
• Margin for requirement, goal likely to be metWavelength [µm]
Poin
t so
urc
e d
ete
ctio
n lim
it(5
, 1
h)
[mJy
]
goal