ESPaDOnS
instrument picture gallery
instrument picture gallery
A large number of photographs (mostly taken by Jacques Cadaugade from OMP) were collected during the various integration phases of ESPaDOnS.
A small selection of them is presented below. Click on the small images to enlarge them.
The Cassegrain unit
The Cassegrain unit as a whole is shown on the right. Detail views of specific subunits or individual components are presented below:
close-up view of the upper part
(calibration/guiding module) with both drawer 1 (atmospheric dispersion corrector/adc) and drawer 2 (calibration wheel) visible;
the tilted mirror hosting the instrument entrance apertures is visible at the bottom of the image, as well as the
viewing/guiding channel (dark horizontal cylinder with attached folding flat mirror on the left of the image);
-
another detailed view of the upper part, with the tilted mirror and entrance aperture at the bottom of the image and the head of the guiding/viewing channel
turret on the left of the image; optical components are inserted (and visible) in the calibration wheel immediately above the tilted mirror;
-
detailed view of the viewing/guiding camera mounted at the other end of the viewing/guiding channel; this camera, designed and
assembled by FingerLake Instrumentation (MaxCam series), includes a Peltier cooled 1kx1k eev ccd with
0.013mm square pixels (type ccd47-10, class 1);
-
close-up view of the tilted mirror
hosting the two instrument entrance apertures; the small central hole (0.22mm) is for collecting photons from the star of interest, while the
larger hole on the side (0.3mm) is for estimating the sky background (in the 'object+sky' spectroscopic mode only); photons that do not
enter the instrument are reflected off towards the viewing/guiding channel;
-
detailed view of drawer 1
once removed from the main structure and taken from above, showing both the adc slice and the rotation mechanism for the top adc prism
(before optics was installed); the rotation mechanism for the second adc prism is on the other side of the drawer;
-
detailed view of drawer 2
taken from below, showing the calibration wheel whose different positions correspond to different sorts of illumination, the open
space being for observations on the sky; optical parts were not yet mounted at the time the image was taken;
-
close-up view of the lower part
(polarimeter) with drawer 3 (first half-wave rhomb), drawer 4 (quarter-wave rhomb) and drawer 6 (with the fabry-perot wheel on
one side and the wollaston/wedge plate slide on the other side) installed, and drawer 5 (second half-wave rhomb) removed to
improve visibility; the two microcontrol barrels holding the two reimaging triplets are visible (at the top and bottom of
the image), as well as the on-axis torque motor rotating the half-wave rhomb (on drawer 3) and the fabry-perot wheel with
associated temperature sensor (on drawer 6);
-
detailed view of drawer 3
taken from below and showing the encoder disk (glued on the non visible side of the central black disc) associated with the
on-axis torque motor, the encoder sensor (metallic sector just above the encoder sector) as well as the encoder electronics
(small circuit board inserted in a rectangular holder at the top of the image); the half-wave rhomb (to be inserted in the
central cylindrical aperture) is not yet mounted;
-
close-up view of encoder circuit board on drawer 3;
-
detailed view of drawer 6
taken from above and showing the fabry-perot wheel (with no optics inside) and its temperature sensor;
-
the fibre bundle coming out of the polarimeter, and conveying photons from the Cassegrain module down to the spectrograph module;
-
detailed view of the calibration box containing
flat-field and spectral reference (thorium) lamps; a short optical fibre conveys light from the lamps (collected on the left edge of
the calibration box) to the main Cassegrain structure;
-
detailed view of the electronic rack containing
all control harware for the Cassegrain module.
The spectrograph
The spectrograph is the main module of ESPaDOnS, both in cost and size.
The top image on the right shows the image slicer module with the slit shutter
(behind the small black disc in the middle) corresponding to where the photons are injected within the spectrograph; after a first pass
on the main collimator (not visible on this image), the beam is dispersed vertically by the grating (on the right side of the image) before
passing a second time on the main
collimator; a first spectrum (running vertically) with all orders overlapping (no cross dispersion) is formed close to the flat mirror (visible at
the immediate left of the slit shutter) before being reflected off to the other side of the spectrograph (transfer collimator, prism train, camera and
dewar, all hiding behind the large black baffles visible on the left side of the image).
The bottom image shows a global view of the spectrograph taken from the other side and with the enclosure removed; while the image slicer module and
the flat mirror are not visible here
(being hidden by the grating mount), one can see (in additition to the grating mount) the main collimator and exposure meter (top right),
the transfer collimator (partly hidden behind the rear baffle), the prism cage and the ccd dewar (partly hidden behind the front baffle). The dioptric
camera between the prism train and the the ccd dewar is entirely hidden by the front baffle.
Selected images of individual components are presented below:
-
close-up view of
the image slicer bench, showing the fibre bundle (on the left) bringing photons from the Cassegrain module along with the manual and
motorised newport stages (both translation and rotation) for positionning the fibre and dedicated optics (three reimaging triplets plus a field doublet
lens) with respect to the rotatable image slicer (hiding behind the central newport stage);
-
another view
of the image slicer bench from above (with the fibre bundle removed); the Bowen-Walraven slicer itself is mounted within the black cylindrical cage
in the middle (popping up perpendicularly to the main optical axis); attendant slicer optics include (from right to left) the entrance triplet
(mounted into the grey newport barrel on the right, and turning the f/3.6 beam coming out of the fibre into a f/21 beam), the field lens (at the immediate
right of the slicer cage, and reimaging the pupil at infinity before entering the slicer) and the two output reimaging triplets (mounted into the
grey newport barrel on the left and turning the f/21 beam into a f/7.6 beam at spectrograph entrance);
-
detailed view
of the main collimator mirror, cut off (along with the transfer collimator) from a parent parabolic mirror of 68cm diameter; the exposure meter
(picking off a very small amount of light from the main beam in its way from the main collimator to the grating) is also visible in the foreground;
-
detailed view
of the exposure meter with the main collimator in the background; the small pickup mirror reflecting off photons towards the exposure meter optics, as
well as the exposure meter shutter, are clearly visible;
-
detailed view
of the 204mm wide and 408mm long R2 diffraction grating in its mount (inspired from the feros design); the grating is tilted downwards
(with 6 invar pins glued on its rear and side surfaces to hold it against gravity) to minimise dust accumulation on the diffracting surface, and semi
circular baffles are included in the bottom part of the mount to reduce straylight from the grating to a minimum;
-
detailed view
of the transfer collimator in its mount; the side panel of the main collimator and part of the mirror itself is also visible on the left of the image
(the rest of the main collimator hiding behind the black baffle);
-
global view of
the last section of the spectrograph optics; photons reflected off the transfer collimator (not visible here) are cross-dispersed by the prism train
(in its black parallelepipedic cage with two handles on top, on the right of the image) and concentrated by the large dioptric camera (black cylinder
with a hook on top of it, in the middle of the image) before being collected onto the ccd detector inside its dewar and vaccuum vessel (pink cylinder on
the left of the image); the thin disc between the prism train and the dioptric camera is the motorised hartmann mask, used to focus automatically the
spectrograph;
-
front
view of the dioptric camera and ccd dewar bench (with hartmann mask and prism cage removed); the huge quadruplet lens at camera entrance (see
optical design) is facing us; this picture was taken when dismounting the spectrograph before shipping;
-
detailed view
of the cross-dispersing prism train within its mount; the whole train can be rotated manually (when aligning the spectrograph) with the newport stage
included in its base;
-
front
view of the prism train and mechanical mount (with Gérard Gallou crossdispersed through it) taken when dismounting the spectrograph;
-
detailed view
of the ccd dewar with its attendant electronics installed on top of it and the permanent evacuated fill/exhaust pipe coming from behind (with further
insulation added around it, forming a yellowish horizontal cylinder on the right side of the image); the dewar mount was designed so that the ccd tilts could
be adjusted to fit the instrument focal plane to within better than 1 arcmin;
-
detailed view
of the eev ccd detector installed in its dewar (with the dioptric camera removed); the physical size of the ccd is 62mm by 28mm, enough to record the
whole optical spectrum produced by the spectrograph;
-
image of
the eev ccd as seen through the dioptric camera;
-
close-up
view of the pressure sensor (accurate to within 0.01mbar) installed within the spectrograph; note the temperature sensor (thin horizontal rod) mounted
on the base of the transfer collimator (upper left corner of image); three such temperature sensors (accurate to within 0.01deg) are installed throughout
the spectrograph enclosure.
The spectrograph enclosure
For a good thermal and spectral stability, the whole spectrograph with its optical table is packed into an insulated enclosure. The enclosure is made
out of an 80mm insulant sandwitched between two layers of epoxy; it consists of three main parts, the bottom section on which the optical table is resting,
as well as two top sections (a large one on the mirrors side and a small one on the ccd side) capping the instrument; three trap doors (two on the large top
section, and one on the small top section) enable access within the instrument for tuning purposes (during the setup stage). The trap door we see here is
that giving access to the transfer collimator, prism cage, dioptric camera and ccd dewar (panel 2).
Colourful pictograms were added on all sides for
those who cannot remember the instrument name. The big marlin with blue dorsal spikes occupying most of trap door 2 (painted by Nicolas Donati, age 9) is shown on the right;
walking around the instrument can also bring you face to face with:
-
a humpback whale bouncing, covering
most of trap door 3 (painted by Nicolas Donati, age 9)
-
a golden-fin marlin with pilot, on trapless
side of the large enclosure top section (painted by Antonin Donati, age 7);
-
a spiky-tail fish, on bottom left
corner of trap door 2 (painted by Nicolas Donati, age 9)
-
a blue bubble fish, on bottom left
corner of trap door 1 (painted by Matteo Donati, age 4)
-
a four-fin scarlet fish,
on one side of the small enclosure top section (painted by Matteo Donati, age 4);
-
a whole shoal of swordfishes cruising
around on the other side of the small enclosure top section;
-
rainbow shark circling around swordfish
shoal with greedy ideas in mind (painted by Nicolas Donati, age 9).
© Jean-François Donati, last update July 21 2004
close-up view of the upper part
(calibration/guiding module) with both drawer 1 (atmospheric dispersion corrector/adc) and drawer 2 (calibration wheel) visible;
the tilted mirror hosting the instrument entrance apertures is visible at the bottom of the image, as well as the
viewing/guiding channel (dark horizontal cylinder with attached folding flat mirror on the left of the image);
another detailed view of the upper part, with the tilted mirror and entrance aperture at the bottom of the image and the head of the guiding/viewing channel
turret on the left of the image; optical components are inserted (and visible) in the calibration wheel immediately above the tilted mirror;
detailed view of the viewing/guiding camera mounted at the other end of the viewing/guiding channel; this camera, designed and
assembled by FingerLake Instrumentation (MaxCam series), includes a Peltier cooled 1kx1k eev ccd with
0.013mm square pixels (type ccd47-10, class 1);
close-up view of the tilted mirror
hosting the two instrument entrance apertures; the small central hole (0.22mm) is for collecting photons from the star of interest, while the
larger hole on the side (0.3mm) is for estimating the sky background (in the 'object+sky' spectroscopic mode only); photons that do not
enter the instrument are reflected off towards the viewing/guiding channel;
detailed view of drawer 1
once removed from the main structure and taken from above, showing both the adc slice and the rotation mechanism for the top adc prism
(before optics was installed); the rotation mechanism for the second adc prism is on the other side of the drawer;
detailed view of drawer 2
taken from below, showing the calibration wheel whose different positions correspond to different sorts of illumination, the open
space being for observations on the sky; optical parts were not yet mounted at the time the image was taken;
close-up view of the lower part
(polarimeter) with drawer 3 (first half-wave rhomb), drawer 4 (quarter-wave rhomb) and drawer 6 (with the fabry-perot wheel on
one side and the wollaston/wedge plate slide on the other side) installed, and drawer 5 (second half-wave rhomb) removed to
improve visibility; the two microcontrol barrels holding the two reimaging triplets are visible (at the top and bottom of
the image), as well as the on-axis torque motor rotating the half-wave rhomb (on drawer 3) and the fabry-perot wheel with
associated temperature sensor (on drawer 6);
detailed view of drawer 3
taken from below and showing the encoder disk (glued on the non visible side of the central black disc) associated with the
on-axis torque motor, the encoder sensor (metallic sector just above the encoder sector) as well as the encoder electronics
(small circuit board inserted in a rectangular holder at the top of the image); the half-wave rhomb (to be inserted in the
central cylindrical aperture) is not yet mounted;
close-up view of encoder circuit board on drawer 3;
detailed view of drawer 6
taken from above and showing the fabry-perot wheel (with no optics inside) and its temperature sensor;
the fibre bundle coming out of the polarimeter, and conveying photons from the Cassegrain module down to the spectrograph module;
detailed view of the calibration box containing
flat-field and spectral reference (thorium) lamps; a short optical fibre conveys light from the lamps (collected on the left edge of
the calibration box) to the main Cassegrain structure;
detailed view of the electronic rack containing
all control harware for the Cassegrain module.
The top image on the right shows the image slicer module with the slit shutter (behind the small black disc in the middle) corresponding to where the photons are injected within the spectrograph; after a first pass on the main collimator (not visible on this image), the beam is dispersed vertically by the grating (on the right side of the image) before passing a second time on the main collimator; a first spectrum (running vertically) with all orders overlapping (no cross dispersion) is formed close to the flat mirror (visible at the immediate left of the slit shutter) before being reflected off to the other side of the spectrograph (transfer collimator, prism train, camera and dewar, all hiding behind the large black baffles visible on the left side of the image).
The bottom image shows a global view of the spectrograph taken from the other side and with the enclosure removed; while the image slicer module and the flat mirror are not visible here (being hidden by the grating mount), one can see (in additition to the grating mount) the main collimator and exposure meter (top right), the transfer collimator (partly hidden behind the rear baffle), the prism cage and the ccd dewar (partly hidden behind the front baffle). The dioptric camera between the prism train and the the ccd dewar is entirely hidden by the front baffle.
Selected images of individual components are presented below:
- close-up view of
the image slicer bench, showing the fibre bundle (on the left) bringing photons from the Cassegrain module along with the manual and
motorised newport stages (both translation and rotation) for positionning the fibre and dedicated optics (three reimaging triplets plus a field doublet
lens) with respect to the rotatable image slicer (hiding behind the central newport stage);
another view
of the image slicer bench from above (with the fibre bundle removed); the Bowen-Walraven slicer itself is mounted within the black cylindrical cage
in the middle (popping up perpendicularly to the main optical axis); attendant slicer optics include (from right to left) the entrance triplet
(mounted into the grey newport barrel on the right, and turning the f/3.6 beam coming out of the fibre into a f/21 beam), the field lens (at the immediate
right of the slicer cage, and reimaging the pupil at infinity before entering the slicer) and the two output reimaging triplets (mounted into the
grey newport barrel on the left and turning the f/21 beam into a f/7.6 beam at spectrograph entrance);
detailed view
of the main collimator mirror, cut off (along with the transfer collimator) from a parent parabolic mirror of 68cm diameter; the exposure meter
(picking off a very small amount of light from the main beam in its way from the main collimator to the grating) is also visible in the foreground;
detailed view
of the exposure meter with the main collimator in the background; the small pickup mirror reflecting off photons towards the exposure meter optics, as
well as the exposure meter shutter, are clearly visible;
detailed view
of the 204mm wide and 408mm long R2 diffraction grating in its mount (inspired from the feros design); the grating is tilted downwards
(with 6 invar pins glued on its rear and side surfaces to hold it against gravity) to minimise dust accumulation on the diffracting surface, and semi
circular baffles are included in the bottom part of the mount to reduce straylight from the grating to a minimum;
detailed view
of the transfer collimator in its mount; the side panel of the main collimator and part of the mirror itself is also visible on the left of the image
(the rest of the main collimator hiding behind the black baffle);
global view of
the last section of the spectrograph optics; photons reflected off the transfer collimator (not visible here) are cross-dispersed by the prism train
(in its black parallelepipedic cage with two handles on top, on the right of the image) and concentrated by the large dioptric camera (black cylinder
with a hook on top of it, in the middle of the image) before being collected onto the ccd detector inside its dewar and vaccuum vessel (pink cylinder on
the left of the image); the thin disc between the prism train and the dioptric camera is the motorised hartmann mask, used to focus automatically the
spectrograph;
front
view of the dioptric camera and ccd dewar bench (with hartmann mask and prism cage removed); the huge quadruplet lens at camera entrance (see
optical design) is facing us; this picture was taken when dismounting the spectrograph before shipping;
detailed view
of the cross-dispersing prism train within its mount; the whole train can be rotated manually (when aligning the spectrograph) with the newport stage
included in its base;
front
view of the prism train and mechanical mount (with Gérard Gallou crossdispersed through it) taken when dismounting the spectrograph;
detailed view
of the ccd dewar with its attendant electronics installed on top of it and the permanent evacuated fill/exhaust pipe coming from behind (with further
insulation added around it, forming a yellowish horizontal cylinder on the right side of the image); the dewar mount was designed so that the ccd tilts could
be adjusted to fit the instrument focal plane to within better than 1 arcmin;
detailed view
of the eev ccd detector installed in its dewar (with the dioptric camera removed); the physical size of the ccd is 62mm by 28mm, enough to record the
whole optical spectrum produced by the spectrograph;
image of
the eev ccd as seen through the dioptric camera;
close-up
view of the pressure sensor (accurate to within 0.01mbar) installed within the spectrograph; note the temperature sensor (thin horizontal rod) mounted
on the base of the transfer collimator (upper left corner of image); three such temperature sensors (accurate to within 0.01deg) are installed throughout
the spectrograph enclosure.
The spectrograph enclosure
For a good thermal and spectral stability, the whole spectrograph with its optical table is packed into an insulated enclosure. The enclosure is made
out of an 80mm insulant sandwitched between two layers of epoxy; it consists of three main parts, the bottom section on which the optical table is resting,
as well as two top sections (a large one on the mirrors side and a small one on the ccd side) capping the instrument; three trap doors (two on the large top
section, and one on the small top section) enable access within the instrument for tuning purposes (during the setup stage). The trap door we see here is
that giving access to the transfer collimator, prism cage, dioptric camera and ccd dewar (panel 2).
Colourful pictograms were added on all sides for
those who cannot remember the instrument name. The big marlin with blue dorsal spikes occupying most of trap door 2 (painted by Nicolas Donati, age 9) is shown on the right;
walking around the instrument can also bring you face to face with:
- a humpback whale bouncing, covering
most of trap door 3 (painted by Nicolas Donati, age 9)
- a golden-fin marlin with pilot, on trapless
side of the large enclosure top section (painted by Antonin Donati, age 7);
- a spiky-tail fish, on bottom left
corner of trap door 2 (painted by Nicolas Donati, age 9)
- a blue bubble fish, on bottom left
corner of trap door 1 (painted by Matteo Donati, age 4)
- a four-fin scarlet fish,
on one side of the small enclosure top section (painted by Matteo Donati, age 4);
- a whole shoal of swordfishes cruising
around on the other side of the small enclosure top section;
- rainbow shark circling around swordfish
shoal with greedy ideas in mind (painted by Nicolas Donati, age 9).
© Jean-François Donati, last update July 21 2004
a humpback whale bouncing, covering
most of trap door 3 (painted by Nicolas Donati, age 9)
a golden-fin marlin with pilot, on trapless
side of the large enclosure top section (painted by Antonin Donati, age 7);
a spiky-tail fish, on bottom left
corner of trap door 2 (painted by Nicolas Donati, age 9)
a blue bubble fish, on bottom left
corner of trap door 1 (painted by Matteo Donati, age 4)
a four-fin scarlet fish,
on one side of the small enclosure top section (painted by Matteo Donati, age 4);
a whole shoal of swordfishes cruising
around on the other side of the small enclosure top section;
rainbow shark circling around swordfish
shoal with greedy ideas in mind (painted by Nicolas Donati, age 9).