caos gerardo avila vadim burwitz carlos guirao jesúsrodriguez · 2012-05-07 · caos fibre...
TRANSCRIPT
5 ‐ 6 May 2012Aspekt 12 ‐ Bad Boll1
Fibre links and Image Slicers
CAOS• Gerardo Avila• Vadim Burwitz• Carlos Guirao• Jesús Rodriguez
CAOS
Contents of our presentation
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Fibre linksFibres for astronomical instrumentsAssembling fibre links
Image slicersReflectiveRefractive
CAOS
Fibre problems
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ThroughputInternal transmissionFresnel lossesFocal ratio degradation (FRD)Circular Vs. rectangular apertures
CouplingLensesEfficiency
AssemblingMaterialsPolishingAlignment
CAOS
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0
10
20
30
40
50
60
70
80
90
100
400 500 600 700 800 900
Internal tran
smission
(%)
Wavelength (nm)
20 m
FBP FVP
Fibre transmission (internal) in 20 m
CAOS
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Gradient Index Fibres ‐ Internal transmission
T T L L' ' /=
CAOS
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Polymicro FIP low OH‐ radicals
A db kmL
T( / ) log= −10
CAOS
FRD origin
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CAOS
FRD in gradient index fibres
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0
10
20
30
40
50
60
70
80
90
100
2 3 4 5 6 7
Efficiency [%
]
F / # Output
FRD62.5um gradient index fibre, 2m, free
F/3.3
F/4.2
F/5
F/6.7
20.01.2009
CAOS
Total transmission of Tapers
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0
10
20
30
40
50
60
70
80
90
100
2 3 4 5 6 7 8 9 10
Total efficiency [%
]
F/# ‐ output
FRDTaper fibre (300um to 100um), 10m, free, spot size 250um,
light source: green HP‐LED (525nm)
F/ 10 (58 % @ F/ 3.3)
F/ 15 (34 % @ F/ 5)
16.06.2009
CAOS
Non‐circular fibres
5 ‐ 6 May 2012Aspekt 12 ‐ Bad Boll10Focal Ratio Degradation study of non‐circular shaped fibresT. Feger, M. Goodwin, C. L. Poppett
CAOS
Pinhole – slit vs. seeing efficiencies
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CAOS
Minimizing FRD with focal reducers
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Image of telescope pupilon input fibre end
CAOS
Minimizing FRD with focal reducers
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Image of star oninput fibre end.
Bad example: not optimal telescope‐fibre pupil matching
CAOS
Minimizing FRD with focal reducers
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Image of star oninput fibre end
CAOS
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GRIN lenses
Telescope pupil on fibre
Star on fibre
CAOS
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Monitoring the star on the fibre end
CAOS
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Monitoring the star on the fibre end
CAOS
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Preparation of a fibre link
Fibre ConnectorFibre Axis
Connector Ax
Ferrule
CAOS
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Aligning a GRIN lens in front of the fibre
CAOS
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Bowen‐Walraven Image Slicer with prisms
CAOS
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Image Slicers – Concept: Reflection
CAOS
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Image Slicers – Concept: Refractor
CAOS
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“Slit” or output fibre end with Image Slicer
Fibre 50um
F/3F/18
308 um spot41 mm
f 5 mm