Download Preliminary fiber bundle design

IRSIS : Preliminary Fiber bundle design
Original datas :
Fiber bundle @ focal plane of F/5,5 telescope primary focal plane - TBC
Telescope FOV : 15’x15’ TBC
Spatial resolution :
18 arcsec (1 µlens @ focal plane)
Spectral resolution :
100
Detector :
1024x1024
IRSIS : Preliminary Fiber bundle design
Manpower :
D.Horville : Optical Engineer
- Design and fabrication of anamorphoser for GIRAFFE spectrograph
On ESO Very Large Telescope
- Desing and fabrication of an Optical Anamorphoser for X-shooter on VLT
-Zemax user, mathematica,Mathcad
B.Lecomte : Technology Engineer
-Characterization of A prototype of spectrograph for FUEGOS (GIRAFFE)
-Characterization of fiber FRD on several fibers
-Technology design, fabrication and delivering of Band 1 detector for HIFI
instrument on Herschel space telescope (launch : 2008)
-Inventor 11 and zemax user (recent).
IRSIS : Preliminary Fiber bundle design
Supplier :
Le verre Fluoré (Rennes, France)
-Fabrication of IRSIS anamorphoser
-Developement and fabrication of IR µlenses matrix.
- Prototype of µlens matrix already done  quality TB improved.
- Confidant with assimbling bundle procedure.
- Wait for «frozen » prototype ordering.
How many fibers and µlens
IRSIS : Preliminary Fiber bundle design
Micro-lenses
Criterii :
- micro-lens f length : Short  exit pupil of telescope @ infinity.
- F ratio of beam focused by µlens > F number of µlens.
- µlens diameter> fiber diameter (core+cladding)
- Image pupil diameter < Micro-lens core
IRSIS : Preliminary Fiber bundle design
Bundle entrance
Square lenses
FL
FL
Fcore
Fcore
Fe
Wt
We
n
e
Fe= 0,95*Fcore
µlens pitch = FL/1,414
Hexagonal lenses
FL
µlens pitch = 2*FL/rac(3)
Fiber diameter(core+cladding)< µlens
IRSIS : Preliminary Fiber bundle design
Entrance µlens charactéristics (calculus)
Telescope = diam.300mm
Aperture = F/12
Fiber diameter = 100 µm
Lens diameter = 315 µm
µlens radius of curv. = 2.3mm
Dimensions available for commercial fabrication.
Check feasibility with infrared materials
IRSIS : Preliminary Fiber bundle design
Fiber description
IR guide type 3
Fcore
100µm
Core index : 1,49 @ 2µm
Cladding index : 1,4765 @ 2µm (NA = 0,2)
Cladding thickness : 40µm
Buffer material : acrylate TBC
Buffer thickness : 5 or 10µm
Buffer cannot be removed (fiber protection)
Fcladding
Fbuffer
180µm
200µm
IRSIS : Preliminary Fiber bundle design
Optimization : Bundle output
Parameters :
µlens diameter : 295µm
Optim :
-lens radius of curvature
-Thickness of µlens
Fixed Files :
-Fiber diameter : 100 µm
-Output NA : 0,2
-Spectro input apert : F/5
200µ
760µm
432µm
IRSIS : Preliminary Fiber bundle design
Bundle output : conclusions
Slit quality is strongly dependant of :
Spectrograph aperture
Entrance F/5 : a good choice
Shape of lens convexe face
Ellipsoïdal lens Vs Spherical
IRSIS : Preliminary Fiber bundle design
Is it a strong goal having a well define slit ?
Low resolution = relax slit quality?  D R ?
IRSIS : Preliminary Fiber bundle design
How to separate lower band and higher band?
Duplicate fiber output?(feasibility, transmission?)
Infrared Dichroïc (losses?)
IRSIS : Preliminary Fiber bundle design
Spectrograph :
Czerny Turner type
F/5 entrance.
Parabolic off axis mirrors
Serious Optimization
 TBDone
IRSIS : Preliminary Fiber bundle design
Strong needs of frozen parameters
 Accurate optimization
Files for bundle and test bench fabrication
Nb of fibers, µlens dimensions, slit length
IRSIS : Preliminary Fiber bundle design
Thermal model?
ISRO, TIPR, CNRS,CNES?
Mechanical design?
LeV.Fluoré / interfaces (TIPR/CNRS)
IRSIS : Preliminary Fiber bundle design
Test Bench
Transmission, quality
Qualification
Vibration, thermal cycling, cooling