Instrument Design/Development Status and System Performance

1
Instrument Design/Development Status andSystem
Performance

• PACS Instrument Overview
• Poglitsch
• MPE

2
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 (5s, 1h)
• Integral field line spectroscopy
• range 57 - 210 µm with 5x5 pixels, image slicer,
  and long-slit grating spectrograph (R 1500)
• two 16x25 GeGa photoconductor arrays
  (stressed/unstressed)
• point source detection limit 28 x10-18 W/m2
  (5s, 1h)

3
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

4
Instrument Overview and Subsystem Responsibilities
5
DPU

• Single point of communication with satellite
• TC/TM
• reception and execution or distribution of
  commands
• transfer of science and HK data
• autonomy functions

6
SPU

• Data compression
• lossy part (average / fit)
• lossless part (redundancy removal)
• Must reduceraw data rate from up to3.6 Mbit/s
  to 120 kbit/s

7
DECMEC

• Photoconductor operation and readout
• CRE supply and timing/control
• detector bias
• signal acquisition
• FPU mechanisms control/ synchronization
• chopper
• filter wheels
• grating
• BOLC data acquisition and control
• Communication with SPU and DPU

8
BOLA / BOLC

• BOLA
• 160-channel JFET buffer at 100 K
• BOLC
• Acquisition of signals from 160 multiplexers in
  bolometer arrays
• Sequencer for bolometer operation / readout
• Control of 300 mK cooler
• Transfer of digitized data to DECMEC

9
FPU/Optics
10
Design/Development Status of Technically Critical
Components

• Optics
• FPU/Structure
• Photoconductors, CRE
• Bolometers
• Chopper
• Grating assembly
• Warm electronics

11
Optics

• Design of FPU optics complete, manufacturing of
  mirror blanks started
• Alignment plan exists tolerancing partly done
• Analyses (geometrical-optical, diffraction) done
  end-to-end for selected cases coverage of
  parameter space (wavelength, chopper angle) to be
  improved in context of instrument calibration
• Baffle design of FPU nearly finished straylight
  analysis difficult
• Calibration sources conceptual design achieved
• Details from N. Geis

12
FPU Status

• Detailed design of FPU structure in final
  phase.Structural problems solved.First part
  (top optics) in manufacturing.
• Delay for manufacturing from some interface
  problems and from late input
• bolometer unit mounting interface
• electrical distribution board design
• detector array cable harness
• filter mounts
• Details from J. Schubert and D. Kampf

13
13
14
Photoconductor Arrays

• Environmental testing successful
• Performance tests on both high and low-stress
  modules with TIA QE looks ok (high-stress gt30)
• Design Changes
• short-circuit immunity implemented in FM design
• Manufacturing Status
• QM completed but FEE integration outstanding
• FM in production
• Problems
• pigtail harness late and hard to fit in FPU
• late readiness of FEEs
• Details from H. Richter and D. Rosenthal

15
Cryogenic Read-Out Electronics

• CREs have undergone complete redesign over the
  last two years
• Progress with new design from both, optimization
  of transistor geometry and of circuit design
• CQM run 032001
• design/layout improvement and local optimization
  of input stage
• successfully tested by IMEC and by CSL, working
  at MPE
• will be used for detector module tests at LENS
• CQM run 102001
• essentially integrator type _024 (as 032001)
• evolutionary combination of additional features
  (4 Cint, increased dynamic range)
• for integration into QM detector modules, dice
  delivery 11/2001
• Details from C. van Hoof

16
CRE032001 Performance

• Cross talk between channels lt1 full range

• Linearity lt3 non-linearity over gt2V

• Noise, linearity, cross talk meet requirements
• Tests of CREs with detectors still ahead (early
  02)

16
17
Bolometer Arrays

• Two complete blue arrays mounted in cryostat at
  LETI for optical characterization
• Red arrays being assembled
• Cold multiplexer/buffer noise (differential
  mode)lt 1 µV/Hz1/2
• Detection efficiency 80(calculated) across
  PACSspectral bands
• Good tolerance to uncertaintyin background level
  shown bymodeling
• Details from L. Rodriguez

18
3He Sorption Cooler

• 300 mK cooler development on track, good margin
  for 46h operation
• Details from L. Duband

19
Chopper

• Status QM
• Manufacturing at MPIA started mid Oct 2001
• Qualification tests started January 2002
• Delivery to MPIA/MPE/KT planned for March 2002,
  but delayed due to pigtail delivery
• Problems
• Damage of flex pivots in lifetime model operation
• Details from R. Hofferbert

20
Grating

• Diffraction Grating Sample received from Zumtobel
  GmbH (A), under evaluation Zeiss for FM
  manufacture as backup
• Actuator ordered from TU Berlin after
  successful performance test at 4K
• Position Sensor ordered from FARRAND after
  successful breadboard test of sensor at 4K
• Bearings coatings and preload control under
  evaluation
• Launch-lock prototype under fabrication
• More information from E. Renotte

21
Warm Electronics Development

• BOLA
• Mechanical design updated
• Box thermal behavior modeling in progress
• JFET modeling for effect of temperature on
  performance in progress
• BOLC
• Mechanical design BOLC updated (2 stacked boxes)
• Analogue board prototype ready for performance
  test
• Bolometer bias board (QM1) ready for design
• 300mK temperature control prototype designed
• FPGA implementation of IEEE1355 under test at CSL
• Most digital functions designed, except bolometer
  sequencer

22
Warm Electronics Development

• DEC/MEC
• DEC/MEC AVM Status
• DSP and DEC simulator available / development on
  schedule
• DEC/MEC EM Status
• design and procurement ongoing, but validation
  with representative hardware pending on mechanism
  simulators availability from partners
• DEC/MEC On-board Software Status
• sequencer complete
• communication 70 tested
• mechanism control low-level S/W 0
• MEC-to-DPU simulator completed Virtuoso OBS
  emulated on a PC
• Successful operation of CRE with DEC prototype
• low noise good linearity

23
Instrument Performance

• Instrument Requirements
• Photometer
• Spectrometer
• Instrument Model
• Optical performance
• Sensitivity budget
• optical transmission
• background
• detector performance

24
Photometer Performance Requirements

• Image quality
• blur telescope limited
• distortion 1 pixel alignment lt1/3 pixel
• Sensitivity (point source detection)
• requirement 5 mJy (5s), 1h of integration
• goal 3 mJy (5s), 1h of integration
• Dynamic range
• detection from 3 mJy to gt1000 Jy (goal 3000 Jy)
• contrast of up to 1500 in one field
• Post-detection bandwidth
• requirement 0.5 - 5 Hz
• goal 0.05 - 5 Hz

25
Spectrometer Performance Requirements

• Image quality
• blur telescope limited
• distortion 1 pixel alignment lt1/4 pixel
• Sensitivity (point source detection)
• requirement 3x10-18 W/Hz1/2 (5s), 1h of
  integration
• goal 2x10-18 W/Hz1/2 (5s), 1h of
  integration
• Dynamic range
• detection from 1x10-18 W to gt10-13 W
• contrast of up to 1100 in one field
• Post-detection bandwidth
• requirement 5 Hz
• goal 10 Hz

26
Optical Performance

• Optical design 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

27
Parameters of PACS Instrument Model(Present Best
Estimate)
(a) Values for the photometry modes from 60-85 or
85-130 µm / 130-210 µm, respectively. (b) The
formal transmission of gt1 takes into account the
acceptance solid angle of the
photoconductor light cones / bolometer baffles
which differs from the beam solid angle.
28
Background, NEP, Spectroscopic and Photometric
Sensitivity
assumed detector QEs 30 (spectroscopy) 80
(photometry) assumed detector NEPs 5x10-18
W/Hz1/2 (spectroscopy) 10-16 W/Hz1/2 (photometry)

• Performance requirements (or even goals) can be
  met