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STATUS REPORT OF FPC. SPICA Task Force Meeting March 29, 2010 MATSUMOTO, Toshio (SNU). Concept of FPC. FPC consists of two instruments FPC-G : Focal plane guiding camera FPC-S : Near infrared camera for scientific observation FPC-S has a back up function of FPC-G - PowerPoint PPT Presentation
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STATUS REPORT OF FPC
SPICA Task Force MeetingMarch 29, 2010
MATSUMOTO, Toshio (SNU)
Concept of FPC
FPC consists of two instrumentsFPC-G: Focal plane guiding cameraFPC-S: Near infrared camera for scientific observation
FPC-S has a back up function of FPC-G
FPC-G and S must have a same FOV and pixel scale with same detector.1K x 1K InSb array (25mm pixel)
ROIC developed for MIRI/JWST by Raytheon5 arc-minutes FOV for 1 frame0.3 arc-second FOV for 1 pixel (~diffraction limit at
5mm)
Detector proposed by Raytheon
• Format: 1024 x 1024 active (plus two columns of reference pixels)
• Pixel Pitch: 25 μm • Input Circuit: SFD (source follower per detector) • Active Fill Factor: > 98% • Spectral Response: 0.4-5.3 μm • Average Quantum Efficiency: > 90% (1 - 5 μm) • Typical Response Uniformity: ≤ 5% (1σ) • Average Dark Current: ≤ 0.02 e-/sec at 30 K • Read Noise: 25 ~ 30 e- for single CDS (~20 e- for 0.4 Hz
eadout)• Power Dissipation: 0.5 mW (0.4 Hz readout), 1.2 mW ( 1Hz
readout) • Well Capacity: 2x105 e- • Outputs: 4 • Reset Modes Global Reset or reset by Row pair • Operating temperature >10 K
Optical design of FPC-G Optical axes of lens group are shifted to improve off axis image
7 lenses with 4 aspherical surfaces
Lens materials are ordinary used ones
Spot size ( I and z band) is typically 10 mm. Maximum size is ~35 mm at a far end from the telescope axis
Distortion effect can be corrected by interpolation formula.
Structure of FPC-G
Cross sectional view of FPC-G
Weight ~ 4kg (Support structure and FPA are not included)
Performance of FPC-GRequired accuracy of the determination of centroid: 0.05 arcsec
Wavelength band: I band (0.8 mm)Detection limit: 18.6 mag (1Hz read out, 25s)Number of stars in 1 frame: ~12 stars (GSCII Catalog)FPC-G can achieve required accuracy
Power dissipation1.2 mW (1 Hz readout), 0.5 mW (0.4 Hz readout)
Optical design of FPC-SFPC-S covers wavelength range from 0.5 mm to 5 mmone more optical element
a little longer than previous design (520 mm)
Spot diagram for white light (0.8-5 mm)
Typical spot size 24 mm Max spot size 31 mm
For monochromatic light2-5mm max spot size ~34 mm0.8-2mm max spot size ~42 mm
Distortion effect can be corrected by interpolation formula. Error of centroid for 4’x4’ field is
average:0.03”, Max 0.06”Error of centroid for 5’x5’ field is
average:0.07”, Max 0.37”
Structure of FPC-S
Weight ~ 6kg (Support structure and FPA are not included)Filter wheel 10 positions (blank, diffuser, 8 filters)
New mode: LVF Spectroscopy
• Three LVFs (Linear Variable Filter) are installed on the filter wheel
cf. 0.8-1.6, 1.4-2.8, 2.5-5• LVF has transmission depending on the
physical position (scanning direction).Wavelength coverage is factor 2
Wavelength resolution is ~ 50.http://www.lwecorp.com/product-literature/lvf_ds_co_ae_042506.pdf
• Slit less spectroscopy at the wavelength range from 0.8 to 5 mm
• Combined with slow scan, surface spectroscopy can be done efficiently for diffuse extended source
Scan direction
↓
← 5 arc-minute → LVF
0.8 mm
1.6 mm
Expected performance of FPC-S
• Assumed parametersTelescope 3-m aperture (7m2)Efficiency 0.5 (Optical + quantum efficiency)Read out noise 20 e- image size 4 pixels
• 3s detection limit for point sources (100 sec integration, R~5) 26.3mag(AB) for all bandsVega magnitudeJ(1.25mm) H(1.6mm) K(2.2mm) L(3.5mm) M(5.0mm)25.5 24.8 24.4 23.4 23.0Photon noise becomes dominant for integration time lon ger than 100 sec3s detection limit for surface brightness (100sec integration, R~5)81 nW.m-2.sr-1
• 3s detection limit fro LVF mode, R~50, integration time ~tPoint sources, Fl 3.4x10-16.l-2.t-1 W.m-2.mm-1 Extended source, l.Fl 8.1x104.l-1.t-1 nW.m-2.sr-1
Line intensity for point source 6.84x10-18.l-1.t-1 W.m-2
Line intensity for extended source 1.62x103.l-1.t-1 nW.m-2.sr-1
Comparison with JWST
• Larger field of viewJWST 2.2x4.4 arcminFPC-SPICA 5x5 arcmin
• Much larger throughputx 20 of JWST
• Capability of surface spectroscopy
• New science that can not be done with JWST will be possible
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