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JWST FGS. An Introduction to the FGS-TFI: The T unable F ilter I mager. Alex Fullerton STScI / HIA. STScI Training for Data Analysts 2008 January 15. Optical Layout of the FGS-TFI. 2048 2048 HgCdTe 5.2 micron cut-off 18 micron pixels. FGS Optical Assembly – TFI Side. - PowerPoint PPT Presentation
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An Introduction to the FGS-TFI:The Tunable Filter Imager
STScI Training for Data Analysts2008 January 15
Alex Fullerton
STScI / HIA
STScI Training for Data Analysts 2008 January 15
Optical Layout of the FGS-TFI
20482048 HgCdTe5.2 micron cut-off18 micron pixels
STScI Training for Data Analysts 2008 January 15
FGS Optical Assembly – TFI Side
TFI POM on Coarse Focus Mechanism
TFI Collimator TMA
TFI Camera
TMA
TFI Detector Assembly (1 FPA)
TFI SIDECar ASIC
TFI ICP -1
Dual Wheel Assembly
Etalon Assembly
KinematicMounts (3)
Optical Alignment Cubes (2)
TFI POM on Coarse Focus Mechanism
TFI Collimator TMA
TFI Camera
TMA
TFI Detector Assembly (1 FPA)
TFI SIDECar ASIC
TFI ICP -1
Dual Wheel Assembly
Etalon Assembly
KinematicMounts (3)
Optical Alignment Cubes (2)
STScI Training for Data Analysts 2008 January 15
Fabry-Perot Etalons
Optical path difference = 2µl cos
Phase difference = (2/) 2µl cos + r
µ=index of refraction
m = 2µl cos + r /2
Tuning: For fixed m, on-axis (=0) l
Detuning: For fixed m, l, off-axis () cos 1 2/2
STScI Training for Data Analysts 2008 January 15
Etalon Coating Design (17 Layers)
65
70
75
80
85
90
95
100
105
110
115
120
1500 2000 2500 3000 3500 4000 4500 5000 2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
Gap (nm)
Wavelength (nm)
Resolution Gap
Non-Functional Waveband
Resolution
m = 3 m = 1
SHORT1500 to 2600 nm~55 filters
LONG3000 to 5000 nm~51 filters
STScI Training for Data Analysts 2008 January 15
Pupil and Filter Wheels
FLAT Lamp
LINE Lamp
Blocking Filters
CLEAR
STScI Training for Data Analysts 2008 January 15
Key Performance Requirements
Parent* TFI Requirement Description Requirement Value Current Design Value
FGS-308 TFI Channel FOV > 4.7 sq. arcmin 4.88 sq. arcmin
FGS-638 TFI Pixel Size 65 mas 64.3 to 65.5 mas
FGS-306 TFI Wavelength Range 1.6 – 2.5 m 3.2 – 4.9 m
1.5 – 2.6 m 3.0 – 5.0 m
FGS-311 TFI Spectral Resolution > 70 & < 150 90 to 115
FGS-315 Wavelength Shift in FOV < 1.0% (50% of FOV) < 0.3% (complete FOV)
FGS-317 TFI Sensitivity at 3.5 m 126 nJy 105 nJy
FGS-355 Coronagraphic Capability 2 Pupil masks 2 Lyot occulters
4 Pupil masks 4 Lyot occulters
NIRCam bandpass TFI
bandpass
- Wavelength Selection Flexibility - Good Sensitivity for Emission Line Objects
- Emission Line Diagnostic Imaging - Coronagraphy: Extrasolar Planets, Brown Dwarfs