47 research outputs found
Applications of DMDs for astrophysical research
A long-standing problem of astrophysical research is how to simultaneously
obtain spectra of thousands of sources randomly positioned in the field of view
of a telescope. Digital Micromirror Devices, used as optical switches, provide
a most powerful solution allowing to design a new generation of instruments
with unprecedented capabilities. We illustrate the key factors
(opto-mechanical, cryo-thermal, cosmic radiation environment,...) that
constrain the design of DMD-based multi-object spectrographs, with particular
emphasis on the IR spectroscopic channel onboard the EUCLID mission, currently
considered by the European Space Agency for a 2017 launch date.Comment: 10 pages, Proc. SPIE 721
The FALCON concept: multi-object spectroscopy combined with MCAO in near-IR
A large fraction of the present-day stellar mass was formed between z=0.5 and
z~3 and our understanding of the formation mechanisms at work at these epochs
requires both high spatial and high spectral resolution: one shall
simultaneously} obtain images of objects with typical sizes as small as
1-2kpc(~0''.1), while achieving 20-50 km/s (R >= 5000) spectral resolution. The
obvious instrumental solution to adopt in order to tackle the science goal is
therefore a combination of multi-object 3D spectrograph with multi-conjugate
adaptive optics in large fields. A partial, but still competitive correction
shall be prefered, over a much wider field of view. This can be done by
estimating the turbulent volume from sets of natural guide stars, by optimizing
the correction to several and discrete small areas of few arcsec2 selected in a
large field (Nasmyth field of 25 arcmin) and by correcting up to the 6th, and
eventually, up to the 60th Zernike modes. Simulations on real extragalactic
fields, show that for most sources (>80%), the recovered resolution could reach
0".15-0".25 in the J and H bands. Detection of point-like objects is improved
by factors from 3 to >10, when compared with an instrument without adaptive
correction. The proposed instrument concept, FALCON, is equiped with deployable
mini-integral field units (IFUs), achieving spectral resolutions between R=5000
and 20000. Its multiplex capability, combined with high spatial and spectral
resolution characteristics, is a natural ground based complement to the next
generation of space telescopes.Comment: ESO Workshop Proceedings: Scientific Drivers for ESO Future VLT/VLTI
Instrumentation, 10 pages and 5 figure
Smart Focal Plane Technologies for VLT Instruments
As we move towards the era of ELTs, it is timely to think about the future
role of the 8-m class telescopes. Under the OPTICON programme, novel
technologies have been developed that are intended for use in multi-object and
integral-field spectrographs. To date, these have been targeted at instrument
concepts for the European ELT, but there are also significant possibilities for
their inclusion in new VLT instruments, ensuring the continued success and
productivity of these unique telescopes.Comment: 5 pages, to appear in the proceedings of the ESO Workshop "Science
with the VLT in the ELT era
Microfabrication of Optically Flat Silicon Micro-Mirrors for Fully Programmable Micro-Diffraction Gratings
AbstractWe have fabricated and characterized a Fully Programmable Micro-Diffraction Grating (FPMDG) with 64 silicon micro-mirrors for spectral shaping in the visible and near-infrared wavelength range. The FPMDG arrays of 50μm and 80μm wide and 700μm long silicon micro-mirrors have been fabricated in a process based on anodic bonding of an 8μm-SOI wafer and a borosilicate glass wafer. The detrimental bending of the micro-mirrors during electrostatic actuation has been minimized through separation of the mechanical and optical sections of the device. Flexures incorporating serpentine structures have been used to reduce the actuation dependence on length and thickness. Independent addressing of the micro-mirrors with negligible cross-talk and with bending of the micro-mirrors smaller than 0.14μm over 700μm have been demonstrated
Programmable CGH on photochromic plates coded with DMD generated masks
Computer Generated Holograms (CGHs) are used for wavefront shaping and complex optics testing. Present technology allows for recording binary CGHs. We propose a Digital Micro-mirror Device (DMD) as a reconfigurable mask, to record rewritable binary and grayscale CGHs on a photochromic plate. Opaque at rest, this plate becomes transparent when it is illuminated with visible light of suitable wavelength. We have successfully recorded the very first amplitude grayscale CGH, with a contrast greater than 50, which was reconstructed with a high fidelity in shape, intensity, size and location. These results reveal the high potential of this method for generating programmable/rewritable grayscale CGHs, which combine DMDs and photochromic substrates
BATMAN: MOS Spectroscopy on Demand
Multi-Object Spectrographs (MOS) are the major instruments for studying primary galaxies and remote and faint objects. Current object selection systems are limited and/or difficult to implement in next generation MOS for space and ground-based telescopes. A promising solution is the use of MOEMS devices such as micromirror arrays, which allow the remote control of the multi-slit configuration in real time. TNG is hosting a novelty project for real-time, on-demand MOS masks based on MOEMS programmable slits. We are developing a 2048×1080 Digital-Micromirror-Device-based (DMD) MOS instrument to be mounted on the Galileo telescope, called BATMAN. It is a two-arm instrument designed for providing in parallel imaging and spectroscopic capabilities. With a field of view of 6.8×3.6 arcmin and a plate scale of 0.2 arcsec per micromirror, this astronomical setup can be used to investigate the formation and evolution of galaxies. The wavelength range is in the visible and the spectral resolution is R=560 for a 1 arcsec object, and the two arms will have 2k × 4k CCD detectors. ROBIN, a BATMAN demonstrator, has been designed, realized and integrated. We plan to have BATMAN first light by mid-2016
The FALCON concept: multi-object adaptive optics and atmospheric tomography for integral field spectroscopy. Principles and performances on an 8 meter telescope
Integral field spectrographs are major instruments to study the mechanisms
involved in the formation and the evolution of early galaxies. When combined
with multi-object spectroscopy, those spectrographs can behave as machines used
to derive physical parameters of galaxies during their formation process. Up to
now, there is only one available spectrograph with multiple integral field
units, e.g. FLAMES/GIRAFFE on the VLT. However, current ground based
instruments suffer from a degradation of their spatial resolution due to
atmospheric turbulence. In this article we describe the performance of FALCON,
an original concept of a new generation multi-object integral field
spectrograph with adaptive optics for the ESO Very Large Telescope. The goal of
FALCON is to combine high angular resolution (0.25 arcsec) and high spectral
resolution (R > 5000) in J and H bands over a wide field of view (10x10
arcmin2) in the VLT Nasmyth focal plane. However, instead of correcting the
whole field, FALCON will use multi-object adaptive optics (MOAO) to perform
locally on each scientific target the adaptive optics correction. This requires
then to use atmospheric tomography in order to use suitable natural guide stars
for wavefront sensing. We will show that merging MOAO and atmospheric
tomography allows us to determine the internal kinematics of distant galaxies
up to z=2 with a sky coverage of 50%, even for objects observed near the
galactic pole. The application of such a concept to Extremely Large Telescopes
seems therefore to be a very promising way to study galaxy evolution from z = 1
to redshifts as high as z = 7.Comment: Monthly Notices of the Royal Astronomical Society, accepte
Space Project for Astrophysical and Cosmological Exploration (SPACE), an ESA stand-alone mission and a possible contribution to the Origins Space Telescope
We propose a new mission called Space Project for Astrophysical and
Cosmological Exploration (SPACE) as part on the ESA long term planning Voyage
2050 programme. SPACE will study galaxy evolution at the earliest times, with
the key goals of charting the formation of the heavy elements, measuring the
evolution of the galaxy luminosity function, tracing the build-up of stellar
mass in galaxies over cosmic time, and finding the first super-massive black
holes (SMBHs) to form. The mission will exploit a unique region of the
parameter space, between the narrow ultra-deep surveys with HST and JWST, and
shallow wide-field surveys such as Roman Space Telescope and EUCLID, and should
yield by far the largest sample of any current or planned mission of very high
redshift galaxies at z > 10 which are sufficiently bright for detailed
follow-up spectroscopy. Crucially, we propose a wide-field spectroscopic
near-IR + mid-IR capability which will greatly enhance our understanding of the
first galaxies by detecting and identifying a statistical sample of the first
galaxies and the first SMBH, and to chart the metal enrichment history of
galaxies in the early Universe - potentially finding signatures of the very
first stars to form from metal-free primordial gas. The wide-field and
wavelength range of SPACE will also provide us a unique opportunity to study
star formation by performing a wide survey of the Milky Way in the near-IR +
mid-IR. This science project can be enabled either by a stand-alone ESA-led M
mission or by an instrument for an L mission (with ESA and/or NASA, JAXA and
other international space agencies) with a wide-field (sub-)millimetre
capability at wavelength > 500 microns
The James Webb Space Telescope
The James Webb Space Telescope (JWST) is a large (6.6m), cold (50K),
infrared-optimized space observatory that will be launched early in the next
decade. The observatory will have four instruments: a near-infrared camera, a
near-infrared multi-object spectrograph, and a tunable filter imager will cover
the wavelength range, 0.6 to 5.0 microns, while the mid-infrared instrument
will do both imaging and spectroscopy from 5.0 to 29 microns. The JWST science
goals are divided into four themes. The End of the Dark Ages: First Light and
Reionization theme seeks to identify the first luminous sources to form and to
determine the ionization history of the early universe. The Assembly of
Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars,
metals, morphological structures, and active nuclei within them evolved from
the epoch of reionization to the present day. The Birth of Stars and
Protoplanetary Systems theme seeks to unravel the birth and early evolution of
stars, from infall on to dust-enshrouded protostars to the genesis of planetary
systems. The Planetary Systems and the Origins of Life theme seeks to determine
the physical and chemical properties of planetary systems including our own,
and investigate the potential for the origins of life in those systems. To
enable these observations, JWST consists of a telescope, an instrument package,
a spacecraft and a sunshield. The telescope consists of 18 beryllium segments,
some of which are deployed. The segments will be brought into optical alignment
on-orbit through a process of periodic wavefront sensing and control. The JWST
operations plan is based on that used for previous space observatories, and the
majority of JWST observing time will be allocated to the international
astronomical community through annual peer-reviewed proposal opportunities.Comment: 96 pages, including 48 figures and 15 tables, accepted by Space
Science Review
MOEMS, the new deformable mirrors for Adaptive Optics
Highly performing adaptive optical systems are required for next
generation giant telescopes as well as next generation
instrumentation for 10 m-class telescopes. Different types of AO
systems are currently under study, including Multi-Conjugate AO
(MCAO), high dynamic range AO, and low-order AO for distributed
partial correction AO. These systems require a large variety of
deformable mirrors with very challenging parameters. The
development of new technologies based on
micro-opto-electro-mechanical systems (MOEMS) is promising for
future deformable mirrors. We are currently developing a MDM based
on an array of electrostatic actuators with attachments to a
continuous mirror on top. The most challenging building block for
this device is the high optical quality mirror. Our first results
show a very efficient planarization of the surface with our
design. The integration of this mirror surface on top of an
actuator array is under investigation