herschel space observatorypacs science verification reviewmpe 22/23 june 2006 gj / mpe 1 pacs test...

GJ / MPE 1

Herschel Space Observatory PACS Science Verification ReviewMPE 22/23 June 2006

PACS Test Facility Capabilities – Cryogenics and OGSE

Gerd Jakob

Future Tests:

GJ / MPE 2


Overview: Test Facility Status for PACS FM ILT

The set-up is basically as described in PACS Cryo Test Equipment and OGSE Specification, PACS-ME-DS-002, Issue 1.1 (Status of CQM).

-> Document to be updated to FM status comprising following revisions:

• Test cryostat: windows and filters• Test optics: design features and alignment upgrade• H2O vapour cell: new design• External blackbody: improvements• Point source masks: status • New molecular FIR laser source at LENS: first results • Test equipment: schematic

GJ / MPE 3


Test cryostat (OGSE 3)• TC is equipped with 2 windows:

– Window 1, diameter 25mm: integr. sphere entrance – Window 2, diameter 85mm: external focus entrance

• Both windows are either equipped with:– Quartz glass for optical alignment verification tests:

Transmission T~76% for λ>35μm

• Or with:– PE foil, 1mm thick, for FM ILT: Transmission

T~80% for λ>35μm

• Window 1 is equipped with:– A manually operated cryo-shutter at ~90K with 2 positions:

• A) open (T=100%) at reference position 0 mm• B) closed (T=0%) at reference position 30 mm

• Window 2 is equipped with:– A manually operated cryo-shutter at ~100K with 3 positions:

• A) FL_E-filter, T~85% for λ>52μm + quartz glass, 0.5mm thick, T~76% for λ>35μm at reference position 8.5 mm

• B) closed (T=0%) at reference position 98.5 mm• C) quartz glass, 0.5mm thick, T~76% for λ>35μm at reference

position 198.5 mm

– 2 fixed filters in series at ~6K (each 2 μm thick mylar foil + Incornel coating): Transmission T~2.4% for λ>35μm, respectively T~0.58% for both filters

Window 1

Window 2

• Test cryostat temperature levels:L0 ~ 1.6K for ~7 days (13 LHe tankful) L1 ~ 4.8K for ~2 days (70 LHe tankful)

GJ / MPE 4


Test optics design• Principal design unchanged to

CQM ILT phase• 2 cryogenic blackbodies (BB):

– Temp. range: 5K – 80K– Absolute temp. accuracy:

+/- 20mK@20K; +/-35mK@50K – Thermal stability:

<+/-1.25mK@30K; <+/-5mK@50K

– Power dissipation: 12.5mW@30K; 35mW@50K

• 1 integrating sphere w. light cone

• 1 external focus access • 2 flip mirrors for optical path

selection (internal or ext. sources)

• 1 chopper wheel to chop between BB1 and BB2: fchop_max@5K=0.457Hz

• 7 Cernox temperature sensors

Z

X

T

C

T C

H

C

P

C

C

P

T

T

T

T

BB1

BB2

integr.sphere

MD3

chopperwheel

M6

M4

MD2

M1

M2

flipmirrormech.1MD1

align.cube

PACS-FPU

test optics housingand baffling system

liquid helium

test opticsrigid supportstructure

P1

F3

P2

P3

F4

P4

P5

CW2

CW1

M3

M5

M7M8

1. TUFIR inputintegr. sphere

2. TUFIR inputpoint source

3. external BB:extented orpoint source

4. water vapour absorption cell w ith BB

alignment with

externalcalibrationsources:

auto collimator

point source maskand X/Y translationstage

C

CF

CF

CF

telescopefocus

CF

C

T

P

c o n t r o lt e m p e r a t u r e r e a d o u t

p o s i t i o n s w i t c h

M D m o t o r d r i v eM m i r r o r

P p u p i lF f o c u sB B b l a c k b o d yC F c r y o g e n i c f i l t e rC W c r y o s t a t w i n d o w

P A C S t e s t c r y o s t a t

4 . 2 K7 7 K

P A C S t e s t o p t i c sG . J a k o b 3 1 . 1 0 . 0 3

F 1

7 7 K1 . 7 K

I F

I F P C I / F

PH

G B 1

G B 2

PHH

F 5

M 9

M 1 0

GB3T

T

T T

GB gear boxhall sensorH

T

A2A1

align.device

A alignment m irror

T T

T

TT

CF

sh

utt

er2

shu

tter

1

F2

TC

backgroundheater

aperture4.2K

light cone

GJ / MPE 5


Test optics alignment (1)

• Complete new optical alignment verification started for FM campaign

• TO internal alignment complete: optimized imaging qualities and target positions achieved with no vignetting:

– BBs and integrating sphere centered on Lyot stop to 1% of diameter each

BB2 BB1

Ext.focusentrance(window2)

Int.sphere

entrance

(window1)

Test optics

PACS FPU

Test cryostat

GJ / MPE 6


Test optics alignment (2)

• Internal and external focus positions verified by use of LED array:– best focus at +/-1mm from

design value– Transverse position good to

+/-0.2mm

• Image quality: – < 3 µm wave front error (PACS)– field distortion less than 1 blue

photometer detector pixel for the total chopped PACS field of view Test optics imager 1 and imager 2 with LED

array in telescope focus position and target in external focus position

IM2

Ext. focustarget

IM1

LED arrayLED array

GJ / MPE 7


Test optics alignment (3)• 1st cryogenic optical alignment verification

test at 5 Kelvin successfully performed• Cryostat equipped with test optics, PACS

mass and optical focus dummy • Autocollimator telescope with digital

camera aligned with cryostat• Additional prism optics mounted to

observe through both windows simultaneously

• 2nd cryogenic reproducibility test planned for June / July

• Preliminary results (after 1st run):– Stability (300K / 5K) of test optics axis

relative to optical bench + PACS dummy: • ~ 0.1 mm in Y and Z direction (position)• < 30” angular

– Stability (300K / 5K) of test optics + cryostat optical bench relative to external window flange:

• ~ 1 mm in +Y direction • ~ 4 mm in -X direction (uncritical)• < 20” angular

– All measured values within design specs.

Autocollimator telescope (ACT) aligned with test cryostat, test optics and reference prism optics

ACT

Prism optics

cryostatwith test optics,PACS mass and optics dummy

GJ / MPE 8


H2O vapour cell• New design with imaging optics,

covering the complete chopped PACS field of view: – Ceramics heater with T=800K– Thermal stability ~+/-1K– Settling time ~1min– Cell will be equipped with (only) 1 PE

window (instead of 2 compared to CQM ILT)

– Gap between cell and cryostat vented with dry N2 gas

– Temperature und pressure data available for housekeeping system

• Expected improvement (compared to CQM ILT):– 10% deep lines relative to measured

continuum for saturated H2O– Improved line contrast of factor ~2-3

• Available for FM ILT to be mounted at test cryostat window 2 position (external focus entrance)

GJ / MPE 9


External Blackbody

• Improved design with well defined pin holes (point sources) in a black painted surface (no structures)

• Available pin holes diameters:0.45 / 0.7 / 1.0 / 1.5 / 2.0 / 4.0 / 10.0 / 15.0 / 25.0 mm

• Temperature range 300K – 1000K

• Thermal stability +/-0.25K• X/Y-stage position reproducibility

<20μm • 30-50% improvement of

contrast (comp. to CQM ILT) by implementation of N2 gas environment

• Design description in PACS-ME-DS-003 will be updated External blackbody mounted

on X/Y-stage at test cryostatwindow 2

GJ / MPE 10


Point source masks• Design description

unchanged from CQM ILT• See document PACS-ME-DS-

003 issue 1 ‘OGSE External Point Source Mask Specification’

• Hot plate temperature up to 600K

• All available hole patterns at their nominal positions in the FOV:

•New: 30-50% improvement of contrast by implementation of N2 gas environment

Hot plate assembled with X/Y-stage at testCryostat window 2

GJ / MPE 11


New Molecular FIR Laser Source at LENS (OGSE 4)

• LENS is building a new molecular laser system:

– CO2 pump laser with ~10 Watts output power; bandwidth 1 MHz

– FIR output power typically mW for ‘strong lines’ and μW for weaker lines

– Bandwidth for a FIR line ~ MHz– Basic FIR lines are covering the

PACS spectral wavelength range

• In early May 2006 a performance demonstration at LENS in a pre-test with MPE’s PACS detector set-up was successful:

– Two available lines were detected: 118.8 μm and 170.5 μm

• For the FM ILT (Sept-Oct) the final FIR source will be shipped to MPE to be installed with the cryostat optics Optical bench with CO2 laser and FIR laser

source during pre-test with PACS detectormodule (integrated with blue test dewar)

CO2FIR

Det.dewar

GJ / MPE 12


New Molecular FIR Laser Source at LENS# FREQUENCY

(THz) WAVELENGTH

(m) WAVENUMBER

(cm-1) Expected output

power 1 4.25167 70.511638 141.821 mW

(no filter trans) 2 3.10594 96.522408 103.603 µW

(no filter trans) 3 2.52278 118.834107 84.151 mW 4 2.25205 133.119600 75.120 µW 5 1.75753 170.576394 58.625 mW 6 1.34135 223.500 44.743 µW 7 1.28832 232.7 42.9738 µW

(no det respo) 8 1.23478 242.79 41.188 µW

(no det respo) 9 1.18215 253.6 39.432 µW

Initial FIR methanol laser wavelengths for PACS spectral calibration test;further lines are feasible after successful technical upgrade of the laser system

GJ / MPE 13

Herschel Space Observatory PACS Science Verification ReviewMPE 22/23 June 2006FIR laser lines, PACS RSRF and 0.5m air

transmission

GJ / MPE 14


New Molecular FIR Laser Source, beam input for FM ILT

• As successfully demonstrated during the pre-test two different optical set-ups are feasible for PACS FM ILT:

– homogenous array illumination with FIR source and integrating sphere optics

– single (or multi) pixel illumination with FIR source via external focus entrance (point source)

– ‘point source’ motion across the slicer

• Improved air transmission feasible by installation of N2 gas vented light pipe optics

• Laser power monitoring by EGSE suggested

GJ / MPE 15


ILT Test Equipment Schematic

LHe4.2 K

PACSFPU

LN2

77 K

1.7 KLHe

I / F

TESTOPTCS

CR

YO

-B

B1

CR

YO

-B

B2

PACS-Testcryostat

cryostattemp diodesMonitor 218

IEE

E/

RS

232

cryostattemp sensors

Monitor 1TIC 304 M

IEE

E

Monitor 2TIC 304 M

IEE

E

4.2 K LHe-LevelModel 135

IEE

E

1.7 K LHe-LevelModel 136

IEE

E

77 K LN2-LevelModel 186

IEE

E

PressureMonitor

PKR 251

RS

232

Motor driveelectronics

RS

232

TempSensors

Monitor 218

IEE

ER

S 232

BB1Controller 370

IEE

ER

S 232

BB2Controller 370

IEE

ER

S 232

BOLC

DEC/MEC

DPU

SPU

XY-StageControl

RS

232

m3/hm3/hvacuum-pump m3/h

Pumping unit He-pump

ext. BBand

controller

gascell

Hot

plat

e

LENS I/F

PCEA300 K Harness

CSL300 K Harness

testoptics300 K Harness

Scanner3716

Scanner3716

PC"Labview"RS 232IEEE

CR

YO

VA

CC

RY

OV

AC

RS

232

XY Stage

Testoptics4 K Harness

4-30

0 K

Har

ness

herschel space observatorypacs science verification reviewmpe 22/23 june 2006 gj / mpe 1 pacs test...

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