The SAFARI instrument - INAF · The SAFARI instrument - summary ... Amplifier Detector read-out and...
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Transcript of The SAFARI instrument - INAF · The SAFARI instrument - summary ... Amplifier Detector read-out and...
The SAFARI instrument (current) baseline concept
13 SPICA and the SAFARI imaging spectrometer - Februari 2013
Instrument requirements/specifications
14 The SAFARI imaging spectrometer - Italian SPICA workshop
Field of view 2' x 2‘ (close to) Nyquist sampled
modes:
photometry / ~ 3
SED mode / ~ 150 - 200
spectroscopy / ~ 2000
line sensitivity few x 10-19 W/√Hz (5σ-1h)
continuum sens. <20 Jy (5σ-1hr)
bright sources up to 1 Jy without ND filter
3 bands:
SW, 34-60 µm 43x43
MW, 60-110 µm 34x34
LW, 110-210 µm 18x18
The SAFARI instrument - summary
• Scanning Fourier Transform Spectrometer with 2’x2’ FoV
• Simultaneously observing in 3 bands (34-210m)
• Ultra sensitive TES detectors/SQUID read out at 50 mK
almost 200 times more sensitive than Herschel
• Frequency Domain Multiplexing
• To be built by an SRON-led consortium
• ~15 institutes in Europe, Canada, Japan - cost ~170M€
15 SPICA and the SAFARI imaging spectrometer - Februari 2013
PHASE A
ROOFTOP Front
optics
Detect
or box
Main body
frame
2 light tight
covers
…a complex instrument result of many design iterations
Scanning FTS
output port 1
BS2 BS1
calibrator
sky input
output port 2
The Mach-Zehnder interferometer
The SAFARI imaging spectrometer - Italian SPICA workshop 16
S(σ)
RS(σ)
TS(σ)
RS(σ,p)
R2 S(σ) +T2 S(σ)
{1+cos(2pσ)}
2RT S(σ)
{1+cos(2pσ)}
The basic Mach-Zehnder interferometer in motion
SPICA and the SAFARI imaging spectrometer - Februari 2013 17
FFT
Instrument toplevel
The SAFARI imaging spectrometer - Italian SPICA workshop 18
Telescope
Focal plane optics:
mirrors, filters, FTS, detectors
Amplifier
Detector read-out and control
Instrument control
Reference design - SAFARI Focal Plane Unit
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Filter wheel FTSM
Mach-Zehnder interferometer
4K-shield around detector box and FPA’s
Input Optics Module with Pick-off-Mirror
Detector filters - SW
The SAFARI imaging spectrometer - Italian SPICA workshop
Focal Plane Assembly
Detector filters – LW/MW 50mK cooler
Shutter
Filter wheel
Calibration source FTSM
SAFARI FPU mechanisms
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FTSM
50mK cooler
SAFARI’s ultimate sensitivity: Transition Edge Sensors
22 SPICA and the SAFARI imaging spectrometer - Februari 2013
Ultimate sensitivity – Transition Edge Sensors
SPICA and the SAFARI imaging spectrometer - Februari 2013 23
• Phonon-noise NEP~T√G Challenges: • ~milli-K environment • Very sensitive to E/B fields • Small pixels (480 μm) and low G trying layout with ‘long thin legs’
Bolometer
G
TESTES
Ta absorberTa absorber SiSixxNNyy legslegs
TESTES
Ta absorberTa absorber SiSixxNNyy legslegs
- G Temperature (~50 milli-K)
Resis
tance
24
Prototype: 8x9 S-band arrays on 250 nm SiN
• 100 % yield, Tc=105 mK (~ 2 %) • NEP=5-6 x10-19 W/√Hz • Varying saturation level
Manufactured to date: 38 x 38 array (M-band) 20 x 20 array (S-band)
Sensitivity reached to date: NEP=5-6 x10-19 W/√Hz
The SAFARI imaging spectrometer - Italian SPICA workshop
Detector system - Focal Plane Assemblies
• Unit to hold TES’s + LC filters + SQUID’s
• One FPA per detector array
• Isolate temperature levels: 50mK/300mK/1.7K
• Shielding: quasi-static B-fields, radiated EMI, stray light
• Challenges
• Multiple functions volume/mass constraints
• High launch loads
• Compact, light-weight B-shield
• Harness for upto ~2000 pixels
The SAFARI imaging spectrometer - Italian SPICA workshop 25