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Fibre Linked ECHelle Astronomical Spectrograph
07-09 May 2010Bebra - Spektroskopietagung 20101
Integration and alignment of FLECHAS
CAOS
CAOS group Astelco
07-09 May 2010Bebra - Spektroskopietagung 20102
Gerardo AvilaVadim BurwitzCarlos GuiraoJesús Rodriguez
Martin DietzelPeter Aniol
CAOS
Purposes of our presentation
07-09 May 2010Bebra - Spektroskopietagung 20103
Summary of our spectrographsFLECHAS specificationsOptical designIntegration and alignment of the instrumentSpectra acquisitionBrief data reduction
CAOS
Spectrographs:
07-09 May 2010Bebra - Spektroskopietagung 20104
Ponchado (reflecting grating) 1994Fiasco (reflecting grating) 1997Loros (prisms) 2001Leches (échelle) 2002Besos (prism) 2003Ingratos (Grism) 2004Tragos (transmission grating) 2005Baches (échelle) 2005Dados (reflecting grating) 2006Pucheros (échelle) in preparation with UCCFlechas (échelle) 2009Next: Flechas++ (échelle)
CAOS
Spectrographs:
07-09 May 2010Bebra - Spektroskopietagung 20105
PONCHADO INGRATOS
BESOS
DADOSTRAGOS LECHES
BACHES
FIASCO
CAOS
FLECHAS requirements
07-09 May 2010Bebra - Spektroskopietagung 20106
Medium resolving power (R: 7000-11000)Wavelength range: 395 nm – 750 nmMechanical stability (no flexures)Adapted to 1.2m telescope at F/10Off the shell optic and mechanic componentsNo moving partsSimple and robust mechanical designLow maintenance
CAOS
Features
07-09 May 2010Bebra - Spektroskopietagung 20107
What drives the design of the spectrograph? :Échelle size !!
Fibre link to the telescope Small fibre coreFibre works at low F/# to reduce focal ratio degradationMini and micro lenses to match telescope and spectrograph apertures
Full parabolic mirror working as off-axisTransmission grating as X-disperserPhoto-tele-objective to image the spectrum on CCDLarge “unexpensive” CCD size.
CAOS
Optical design
07-09 May 2010Bebra - Spektroskopietagung 20108
Full parabola as collimator
Output fibre end
CCD Tele-objective X-disperser Échelle
9º
CAOS
Optical design
07-09 May 2010Bebra - Spektroskopietagung 20109
To the question: why 9º between the collimator and objective beams?
This “grating” angle should be as small as possible in order to approach the Littrow configuration where the efficiency is the maximum. In the FLECHAS case, we found that 9º was the best compromise between the size of the camera objective and the optical table.
CAOS
Spectrograph
07-09 May 2010Bebra - Spektroskopietagung 201010
Parabola f 444 mm, ø 75 mm, Edmund OpticsCollimator beam F/18Pupil 25 mmÉchelle 79 li/mm 63º 25 50 9, ThorlabsX-disperser 200 li/mm 10º 58 58 10, NewportObjective f 200 F/2.8, CanonCCD Atik 11000 4008 2672 9 µm (24 35)
CAOS
Fibre link
07-09 May 2010Bebra - Spektroskopietagung 201011
Telescope1.2 m at F/10Plate scale: 58.2 µm/arcsecPinhole: 150 µm = 2.6 arcsec
Fibre 50 µm and 20 m long, Polymicro FBPInput lens GRIN f = 450 µm, L = 1 mm,
ø 0.5 mm, GrinTechConversion beam F/10 to F/3 in fibreOutput lens Doublet f = 5 mm, ø 3 mm, Linos“Slit” ø 308 µm at F/18
CAOS
Beam injection
07-09 May 2010Bebra - Spektroskopietagung 201012
s
f = 450um f '
φ
F/10 tel
F/3 fib Telescope pupil 45 umTelescope Image (Star 150 um)
F F '
50 um
We have use the principle to projectthe telescope pupil on the fibre input end
CAOS
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Inte
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(%)
Wavelength (nm)
20 m
FBP FVP
Fibre transmission (internal) in 20 m. FLECHAS uses the FBP type
CAOS
Fibre Head
07-09 May 2010Bebra - Spektroskopietagung 201014
motorized 45ºmirror forTh-Ar lamp
micro-lens in front of fibre
200 µm Ni pinhole in front of micro-lens
pinhole viewer
95ºsolenoid
fibre input explosion
CAOS
Output Beam
07-09 May 2010Bebra - Spektroskopietagung 201015
Fibre 50um
F/3F/18
308 um spot41 mm
f 5 mm
CAOS
This fibre link for a 30 cm Telescope
07-09 May 2010Bebra - Spektroskopietagung 201016
Best match F/10 telescopePlate scale 14.5 µm/arcsecSky aperture 10.3 arcsec ! (150 µm pinhole)
F/3 in fibre: good FRD100 µm pinhole => 6.9 arcsec, but the aperture into
the fibre falls to F/4.5. The FRD isat the limit of acceptance
Increasing resolution? The output spot is 308 µm.Need of an image slicer!
CAOS
Steps to integration and alignment
07-09 May 2010Bebra - Spektroskopietagung 201017
Setup of the 9º angle between collimator and ÉchelleSetup of the fibre-parabola optical axisAlignment of parabola with respect to the optical axisInstallation of auto-collimator mirrorFinding the parabola focusAlignment of the output fibre endAlignment of the ÉchelleAlignment of the objective and cameraAlignment of the cross-disperserInstallation of the enclosureExample of spectra and calibration data reduction
CAOS
Set up of the optical table
07-09 May 2010Bebra - Spektroskopietagung 201018
300 mm
600 mm lower cover
posts
CAOS
Definition of the 9º angle between collimator and Échelle
07-09 May 2010Bebra - Spektroskopietagung 201019
the other side of theruler set 9º
one side of ruler parallel to breadboard
9º
CAOS
Alignment of parabola by auto-collimation
07-09 May 2010Bebra - Spektroskopietagung 201020
CAOS
Definition of the parabola optical axis with a laser
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axis 55mm above breadboard
adjust height of parabola with a paper
mask and a hole in center
CAOS
Alignment of parabola
07-09 May 2010Bebra - Spektroskopietagung 201022
adjust center of parabola in “x-y” untillaser beam returns.
tilt parabola in y untillaser beam returns
…then clamp parabola to base
CAOS
Installation of auto-collimator mirror
07-09 May 2010Bebra - Spektroskopietagung 201023
set a flat mirror with a hole,
in front of parabola
with the help of anothersmall flat mirror
tilt thebig flat mirror
until laser returns
flat mirror faces nowparabola in auto-collimation
laser can nowbe removed
set a test fibre ~ in focusof parabola: 444mm
CAOS
Finding the parabola focus
07-09 May 2010Bebra - Spektroskopietagung 201024
inject laser in fibre. The outputis projected to the parabola
The collimated beam is projectedto the flat mirror, backto parabola, then
back to fibre. Focus is locatedwhere input and output coincide.
To ease the focusing processreduce the parabola with a
paper mask with two windows.
the projected laser beam will be
only reflected in these windows
CAOS
Finding the parabola focus
07-09 May 2010Bebra - Spektroskopietagung 201025
laser beam is collimated byparabola
the beam is reflected in flat mirror
and un-do its way back
parabola focus is located when
both returned images coincide in space with the output fibre
test fibre is now in parabola focus
we can also remove flat mirror
CAOS
Alignment of the output fibre end
07-09 May 2010Bebra - Spektroskopietagung 201026
set a microscope with reticule infront of test fibre
Locate output fibre position.
center and focus in reticule theimage of the output fibre
do not touch or move the fibre!!
adjust position and focus with the microscope only!!
remove test fibre. Do not touch microscope anymore!!
set final output fibre in front ofthe microscope.
Slide fibre output in its supportuntil image focuses in rotation center (white screen).
CAOS
Alignment of the output fibre end
07-09 May 2010Bebra - Spektroskopietagung 201027
the fibre support permits rotation In two axis...
to center a laser beam projectedby output fibre (F/#=18.5)
to be centered off-axis in left window of parabola
now clamp the fibre to thebread-board
CAOS
Alignment of the Échelle
07-09 May 2010Bebra - Spektroskopietagung 201028
install the echelle support nextto fibre output.
Be careful not vignettingfibre output!!
center collimated laser beamin the inclined echelle surface
use echelle to mark the secondaxis parallel to bread-board
rotate echelle until laser beam isprojected against a paper screen
adjust rotation until projectionis parallel to bread-board
CAOS
Alignment of the objective and camera
07-09 May 2010Bebra - Spektroskopietagung 201029
fix a paper mask to the capof the objective
center laser projection on the objective
slide back until camera is left outside enclosure
Be careful not vignetting the collimated beam from parabola!
CAOS
Alignment of the cross-disperser
07-09 May 2010Bebra - Spektroskopietagung 201030
set x-disperser between echelleand objective
slide it untilbeam projectsin center of objective
Slide x-disperser just beforevignetting collimated beam from parabola
remove paper masksfrom parabola and
objective
tight clamps from all components!
alignment is now completed!
CAOS
Centring, rotation and focus of the spectrum
07-09 May 2010Bebra - Spektroskopietagung 201031
A
AB
B
C
C
BC Focus
Focus
CAOS
Installation of the enclosure
07-09 May 2010Bebra - Spektroskopietagung 201032
enclosure is reinforced insidewith neoprene stripes to prevent/reduce light pollution
cuts in enclosure are also covered with neoprene.
with a cut forCCDcamera
and a cut forthe fibre
enclosure is mountedapart
CAOS
Handles to take it away !
07-09 May 2010Bebra - Spektroskopietagung 201033
enclosure is nowcompleted!! attach handles
remove posts with rubber feet
Ready!
CAOS
Wavelength calibration
07-09 May 2010Bebra - Spektroskopietagung 201034
With MIDAS (also available in Windows with Cygwin)Based in “SET CONTEXT/ECHELLE”Requires:
Spectrum of a halogen lamp for order identificationSpectrum of a thorium-argon lamp for line identificationAn Atlas of a Thorium-Argon spectrum 400-900nm
Provides:Semi-automatic calibration: Two pair of lines are identified by hand, 1300 lines automaticallyResolving Power (R=λ/Δλ) calculated in 1000 lines Order by order calibration andit merges all orders in one continued spectrum
CAOS
Orientation
07-09 May 2010Bebra - Spektroskopietagung 201035
RED
REDBLUE
BLUE
CAOS
Spectrum repetition
07-09 May 2010Bebra - Spektroskopietagung 201036
CAOS
Identifying orientation
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RED
BLUE
BLUE?RED?
RED
CAOS
Identifying orientation
07-09 May 2010Bebra - Spektroskopietagung 201038
BLUE RED
CAOS
Calibration data:
07-09 May 2010Bebra - Spektroskopietagung 201039
Spectrum of an halogen lamp:
Spectrum of a thorium-argon lamp:
CAOS
Order identification
07-09 May 2010Bebra - Spektroskopietagung 201040
CAOS
Th-Ar. how many lines?
07-09 May 2010Bebra - Spektroskopietagung 201041
~2000!
CAOS
First, manual line identification:
07-09 May 2010Bebra - Spektroskopietagung 201042
CAOS
Then, automatic line identification:
07-09 May 2010Bebra - Spektroskopietagung 201043
~1300 lines identified!
CAOS
Tolerance in the identification
07-09 May 2010Bebra - Spektroskopietagung 201044
CAOS
Resolving Power (R=λ/Δλ)
07-09 May 2010Bebra - Spektroskopietagung 201045
CAOS
Spectrum of the Sun order by order
07-09 May 2010Bebra - Spektroskopietagung 201046
CAOS
Merged spectrum of the Sun
07-09 May 2010Bebra - Spektroskopietagung 201047
CAOS
Detailed spectrum of the Sun
07-09 May 2010Bebra - Spektroskopietagung 201048
Natrium doublet
CAOS
Optical efficiency
07-09 May 2010Bebra - Spektroskopietagung 201049
Fibre link 60 %Parabola 90 %Échelle 50 % (including vignetting)X-disperser 78 %Canon objective 90 %
Total 19 %
CAOS
Optical efficiency
07-09 May 2010Bebra - Spektroskopietagung 201050
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Wavelength (nm)
Canon 200mm F/2.8 EF
CAOS
Optical efficiency
07-09 May 2010Bebra - Spektroskopietagung 201051
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X-disperser Newport
CAOS
Improvements
07-09 May 2010Bebra - Spektroskopietagung 201052
Image slicer to increase resolution (x1.8)CCD camera with higher QE (QSI?)Mechanical improvements
Échelle support with tiltFibre support with height adjustmentSmaller and light tightness enclosure
CAOS
Image slicer
07-09 May 2010Bebra - Spektroskopietagung 201053
CAOS
07-09 May 2010Bebra - Spektroskopietagung 201054
Image slicer
CAOS
Alignment verification after transport
07-09 May 2010Bebra - Spektroskopietagung 201055
The alignment tool set a set a paper maskto parabola with
a tiny hole in center
inject a laser through inclinedtool holes
when aligned, the reflected laser should always hit the same reference point.
when aligned, the laser should hit the parabola in its center
CAOS
Alignment verification after transport
07-09 May 2010Bebra - Spektroskopietagung 201056
fix a flat mirror in its support.It has been previously alignedfor auto-collimation
Inject laser In fibre.
beam returns byauto-collimation
alignment is correctif beam returns in same output
CAOS
Mechanical parts
07-09 May 2010Bebra - Spektroskopietagung 201057
echelle
CAOS
Mechanical parts
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echelle
CAOS
Mechanical parts
07-09 May 2010Bebra - Spektroskopietagung 201059
echelle
CAOS
Mechanical parts
07-09 May 2010Bebra - Spektroskopietagung 201060
echelle
CAOS
Mechanical parts
07-09 May 2010Bebra - Spektroskopietagung 201061
echelle
CAOS
07-09 May 2010Bebra - Spektroskopietagung 201062
Thank you for your patience and attention !
CAOS web page:
spectroscopy.wordpress.com
ASTELCO web page:
http://www.astelco.com/