IRSIS : Preliminary Fiber bundle design Original datas : Fiber focal plane of F/5,5 telescope primary focal plane - TBC Telescope FOV : 15’x15’ TBC Spatial resolution : 18 arcsec (1 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 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 µlens pitch LL LL tt ee e µlens pitch =  L/1,414  core Fiber diameter(core+cladding)< µlens  core ee  e= 0,95 *  core n µlens pitch = 2*  L/rac(3) LL Square lenses Hexagonal lenses Bundle entrance

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  core 100µm Core index : 2µm Cladding index : 2µm (NA = 0,2) Cladding thickness : 40µm Buffer material : acrylate TBC Buffer thickness : 5 or 10µm Buffer cannot be removed (fiber protection)  cladding 180µm  buffer 200µm IR guide type 3

IRSIS : Preliminary Fiber bundle design Optimization : Bundle output Parameters : Optim : -lens radius of curvature -Thickness of µlens Fixed Files : -Fiber diameter : 100 µm -Output NA : 0,2 -Spectro input apert : F/5 200µ 760µm432µm µlens diameter : 295µm

IRSIS : Preliminary Fiber bundle design Bundle output : conclusions Slit quality is strongly dependant of : Entrance F/5 : a good choice Spectrograph aperture Ellipsoïdal lens Vs Spherical Shape of lens convexe face

IRSIS : Preliminary Fiber bundle design Is it a strong goal having a well define slit ? Low resolution = relax slit quality?   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