PACS IBDR 27/28 Feb 2002 PACS Instrument Overview1 Instrument Design/Development Status and System...

PACS Instrument Overview 1

PACS IBDR 27/28 Feb 2002

Instrument Design/Development Status and

System Performance

PACS Instrument Overview

A. Poglitsch

MPE



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 2…8 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”



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



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/ANTEC/IMEC

BlueBolArray &Read-out

CEA

RedBolArray &Read-out

CEA

RedGe:GaArray &CRE

MPE/ANTEC/IMEC

0.3K Cooler CEA

Grating Assy CSL-Liege

Chopper Assy MPIA

2FilterWheels KT

2BlackBodies 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



DPU

• Single point of communication with satellite

• TC/TM– reception and

execution or distribution of commands

– transfer of science and HK data

– autonomy functions



DPU

(NOM)

(RED)

SPU 1(NOM)

SPU 2(RED)

DEC/MEC 1

DEC/MEC 2

1355 SWL-SPU1/2SWL DETECTORDATA & STATUS

1355 LWL-SPU1/2LWL DETECTORDATA & STATUS

SPU1 ANALOG HK DATA

SPU2 ANALOG HK DATA

S/C CMD

S/C CMD

28V+SYNC

28V+SYNC

1355 SWL-SPU1TC/TM

1355 LWL-SPU1TC/TM

1355 SWL-SPU2TC/TM

1355 LWL-SPU2TC/TM

SWL-SPU

LWL-SPU

PSU

DAU

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



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



BOLA / BOLC

BOLA• 160-channel JFET

buffer at ~100 KBOLC• 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



FPU/Optics

FPU Cold FocalPlaneUnit

KT/MPE

BlueGe:GaArray &CRE

MPE/ANTEC/IMEC

BlueBolArray &Read-out

CEA

RedBolArray &Read-out

CEA

RedGe:GaArray &CRE

MPE/ANTEC/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



Design/Development Status of Technically Critical Components

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



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



• 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

FPU Status



13



• Environmental testing successful• Performance tests on both high and low-stress

modules with TIA: QE looks ok (high-stress: >30%)

• 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

Photoconductor Arrays



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



CRE032001 Performance

• Linearity : <3% non-linearity over >2V

• Cross talk between channels: <1% full range

• Noise, linearity, cross talk~ meet requirements

• Tests of CREs with detectors still ahead (early ’02)

16



Bolometer Arrays

• Two complete “blue” arrays mounted in cryostat at LETI for optical characterization

• Red arrays being assembled• Cold multiplexer/buffer noise (differential mode)

< 1 µV/Hz1/2

• Detection efficiency 80%(calculated) across PACSspectral bands

• Good tolerance to uncertaintyin background level shown bymodeling

Details from L. Rodriguez



3He Sorption Cooler

• 300 mK cooler development on track, good margin for 46h operation

Details from L. Duband



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



Grating

• Diffraction Grating Sample received from Zumtobel GmbH (A),

under evaluationZeiss for FM manufacture as backup

• Actuator ordered from TU Berlin after successfulperformance test at 4K

• Position Sensor ordered from FARRAND after successfulbreadboard test of sensor at 4K

• Bearings coatings and preload control under evaluation

• Launch-lock prototype under fabrication

More information from E. Renotte



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



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

Slopes @ 4K

2

2,5

3

3,5

4

4,5

5

500 510 520 530 540 550 560 570 580 590 600

sample

ou

tpu

t (

Vo

lts

)

CRE 03/01 @ 4K



Instrument Performance

• Instrument Requirements– Photometer– Spectrometer

• Instrument Model– Optical performance– Sensitivity budget

• optical transmission• background• detector performance



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



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



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



(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 Best Estimate)



Background, NEP, Spectroscopic and Photometric Sensitivity

Performance requirements (or even goals) can be met

assumed detector QEs: 30% (spectroscopy); 80% (photometry) assumed detector NEPs: 5x10-18 W/Hz1/2 (spectroscopy); 10-16 W/Hz1/2 (photometry)

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