PACS Test Facility Capabilities Cryogenics and OGSE

1
PACS Test Facility Capabilities Cryogenics
and OGSE
Future Tests

• Gerd Jakob

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).
• -gt 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

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 T76 for ?gt35µm
• Or with
• PE foil, 1mm thick, for FM ILT
  Transmission T80 for ?gt35µm
• Window 1 is equipped with
• A manually operated cryo-shutter at 90K with 2
  positions
• A) open (T100) at reference position 0 mm
• B) closed (T0) at reference position 30 mm
• Window 2 is equipped with
• A manually operated cryo-shutter at 100K with 3
  positions
• A) FL_E-filter, T85 for ?gt52µm quartz glass,
  0.5mm thick, T76 for ?gt35µm at reference
  position 8.5 mm
• B) closed (T0) at reference position 98.5 mm
• C) quartz glass, 0.5mm thick, T76 for ?gt35µm at
  reference position 198.5 mm

Window 2
Window 1

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

4
Test optics design

• Principal design unchanged to CQM ILT phase
• 2 cryogenic blackbodies (BB)
• Temp. range 5K 80K
• Absolute temp. accuracy /-
  20mK_at_20K /-35mK_at_50K
• Thermal stability
  lt/-1.25mK_at_30K lt/-5mK_at_50K
• Power dissipation 12.5mW_at_30K 35mW_at_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_at_5K0.457Hz
• 7 Cernox temperature sensors

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
Test optics
Ext.focus entrance (window2)
Int.sphere entrance (window1)
PACS FPU
Test cryostat
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
• lt 3 µm wave front error (?PACS)
• field distortion less than 1 blue photometer
  detector pixel for the total chopped PACS field
  of view

Ext. focus target
IM1
IM2
LED array
Test optics imager 1 and imager 2 with LED array
in telescope focus position and target in
external focus position
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)
• lt 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)
• lt 20 angular
• All measured values within design specs.

cryostat with test optics, PACS mass and optics
dummy
Prism optics
ACT
Autocollimator telescope (ACT) aligned with test
cryostat, test optics and reference prism optics
8
H2O vapour cell

• New design with imaging optics, covering the
  complete chopped PACS field of view
• Ceramics heater with T800K
• 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)

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 lt20µm
• 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
cryostat window 2
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

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

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

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 MPEs 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

Det. dewar
FIR
CO2
Optical bench with CO2 laser and FIR laser
source during pre-test with PACS detector module
(integrated with blue test dewar)
12
New Molecular FIR Laser Source at LENS
Initial FIR methanol laser wavelengths for PACS
spectral calibration test further lines are
feasible after successful technical upgrade of
the laser system
13
FIR laser lines, PACS RSRF and 0.5m air
transmission
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

15
ILT Test Equipment Schematic