As a consequence of the evolution in the design and of the modularity of its components, AOLI for the William Herschel Telescope (WHT 4.2m) is much smaller and more efficient than its previous designs. This success has leaded us to plan to condense it even more to get a portable and easy to integrate system, ALIOLI (Adaptive and Lucky Imaging Optics Lightweight Instrument). It consists of a DM+WFS module with a lucky imaging science camera attached. ALIOLI is an AO instrument for the 1-2m class telescopes which will also be used as on-sky testbench for AO developments. Here we describe the setup to be installed at the 1.5m Telescopio Carlos Snchez (TCS) at the Spanish Observatorio del Teide (Tenerife, Canary Islands).
Here we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art instrument which makes use of two well proved techniques, Lucky Imaging (LI) and Adaptive Optics (AO), to deliver diffraction limited imaging at visible wavelengths, 20 mas, from ground-based telescopes. Thanks to its revolutionary TP3-WFS, AOLI shall have the capability of using faint reference stars. In the extremely-big telescopes era, the combination of techniques and the development of new WFS systems seems the clue key for success. We give details of the integration and verification phases explaining the defiance that we have faced and the innovative and versatile solutions for each of its subsystems that we have developed, providing also very fresh results after its first fully-working observing run at the William Herschel Telescope (WHT).
The combination of Lucky Imaging with a low order adaptive optics system was demonstrated very successfully on the Palomar 5m telescope nearly 10 years ago. It is still the only system to give such high-resolution images in the visible or near infrared on ground-based telescope of faint astronomical targets. The development of AOLI for deployment initially on the WHT 4.2 m telescope in La Palma, Canary Islands, will be described in this paper. In particular, we will look at the design and status of our low order curvature wavefront sensor which has been somewhat simplified to make it more efficient, ensuring coverage over much of the sky with natural guide stars as reference object. AOLI uses optically butted electron multiplying CCDs to give an imaging array of 2000 x 2000 pixels.
The Adaptive Optics Lucky Imager, AOLI, is an instrument developed to deliver the highest spatial resolution ever obtained in the visible, 20 mas, from ground-based telescopes. In AOLI a new philosophy of instrumental prototyping has been applied, based on the modularization of the subsystems. This modular concept offers maximum flexibility regarding the instrument, telescope or the addition of future developments.
The FastCam instrument platform, jointly developed by the IAC and the UPCT, allows, in real-time, acquisition, selection and storage of images with a resolution that reaches the diffraction limit of medium-sized telescopes. FastCam incorporates a specially designed software package to analyse series of tens of thousands of images in parallel with the data acquisition at the telescope. Wide FastCam is a new instrument that, using the same software for data acquisition, does not look for lucky imaging but fast observations in a much larger field of view. Here we describe the commissioning process and first observations with Wide FastCam at the Telescopio Carlos Sanchez (TCS) in the Observatorio del Teide.
Lucky Imaging combined with a low order adaptive optics system has given the highest resolution images ever taken in
the visible or near infrared of faint astronomical objects. This paper describes a new instrument that has already been
deployed on the WHT 4.2m telescope on La Palma, with particular emphasis on the optical design and the predicted
system performance. A new design of low order wavefront sensor using photon counting CCD detectors and multi-plane
curvature wavefront sensor will allow virtually full sky coverage with faint natural guide stars. With a 2 x 2 array of
1024 x 1024 photon counting EMCCDs, AOLI is the first of the new class of high sensitivity, near diffraction limited
imaging systems giving higher resolution in the visible from the ground than hitherto been possible from space.
AOLI, Adaptive Optics Lucky Imager, is the next generation of extremely high resolution instruments in the optical
range, combining the two more promising techniques: Adaptive optics and lucky imaging. The possibility of reaching
fainter objects at maximum resolution implies a better use of weak energy on each lucky image. AOLI aims to achieve
this by using an adaptive optics system to reduce the dispersion that seeing causes on the spot and therefore increasing
the number of optimal images to accumulate, maximizing the efficiency of the lucky imaging technique.
The complexity of developments in hardware, control and software for in-site telescope tests claim for a system to
simulate the telescope performance. This paper outlines the requirements and a concept/preliminary design for the
William Herschel Telescope (WHT) and atmospheric turbulence simulator. The design consists of pupil resemble, a
variable intensity point source, phase plates and a focal plane mask to assist in the alignment, diagnostics and calibration
of AOLI wavefront sensor, AO loop and science detectors, as well as enabling stand-alone test operation of AOLI.
The FastCam instrument, jointly developed by the IAC and the UPCT, allows, in real-time, acquisition, selection and
storage of images with a resolution that reaches the diffraction limit of medium-sized telescopes. FastCam incorporates a
specially designed software package to analyze series of tens of thousands of images in parallel with the data acquisition
at the telescope.
This instrument, well tested and used, has lead to another instrument with slightly different characteristics: Wide
FastCam. Although it uses the same software for data acquisition, this time the objective does not look for lucky imaging
but fast observations (some frames per second) in a much larger field of view. Wide FastCam consists of a 1k x 1k
EMCCD detector and different optics offering a ~8 arcmin FOV.
IDOM collaborated with IAC in the design of a high stability optical bench for the implementation of FastCam at the
Telescopio Carlos Sánchez (TCS) and is currently collaborating in the implementation of Wide FastCam at the same
The highest resolution images ever taken in the visible were obtained by combining Lucky Imaging and low order
adaptive optics. This paper describes a new instrument to be deployed on the WHT 4.2m and GTC 10.4 m telescopes on
La Palma, with particular emphasis on the optical design and the expected system performance. A new design of low
order wavefront sensor using photon counting CCD detectors and multi-plane curvature wavefront sensor will allow
dramatically fainter reference stars to be used, allowing virtually full sky coverage with a natural guide star. This paper
also describes a significant improvements in the efficiency of Lucky Imaging, important advances in wavefront
reconstruction with curvature sensors and the results of simulations and sensitivity limits. With a 2 x 2 array of 1024 x
1024 photon counting EMCCDs, AOLI is likely to be the first of the new class of high sensitivity, near diffraction
limited imaging systems giving higher resolution in the visible from the ground than hitherto been possible from space.
The Adaptive Optics Lucky Imager (AOLI) is a new instrument under development to demonstrate near diffraction
limited imaging in the visible on large ground-based telescopes. We present the adaptive optics system being designed
for the instrument comprising a large stroke deformable mirror, fixed component non-linear curvature wavefront sensor
and photon-counting EMCCD detectors. We describe the optical design of the wavefront sensor where two photoncounting
CCDs provide a total of four reference images. Simulations of the optical characteristics of the system are
discussed, with their relevance to low and high order AO systems. The development and optimisation of high-speed
wavefront reconstruction algorithms are presented. Finally we discuss the results of simulations to demonstrate the
sensitivity of the system.
FastCam is an instrument jointly developed by the Instituto de Astrofísica de Canarias (IAC) and the Universidad
Politécnica de Cartagena (UPCT), designed to obtain high spatial resolution images in the optical wavelength range from
ground-based telescopes (http://www.iac.es/proyecto/fastcam and
http://www.iac.es/telescopes/Manuales/manualfastcam.pdf). The instrument is equipped with a very low noise and very
fast readout speed EMCCD camera which provides short exposure images to an FPGA-based processor which performs
the selection, recenterg and combination of images in real-time (applying Lucky Imaging techniques) to provide
diffraction limited resolution images in 1-4 m class telescopes from 500 to 1100 nm.
IDOM has contributed to this new state-of-the-art instrument with the design of an optomechanical system conceived to
maximize the image scale stability of the system for astrometry. The combination of aluminum plates, carbon fiber
(CFRP) rods and stainless steel mounts in the optical bench defines an athermalized and stiff design to meet the
requirements of thermal and mechanical stability.
This work has been done with the support of the Aerospace Subprogramme of the Spanish Centre for the Development
of Industrial Technology (CDTI) and the INTEK programme of the Basque Development Agency (SPRI).
In this paper, we present an original observational approach, which combines, for the first time, traditional
speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high
contrast (10-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet
filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the
2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect
L-type brown dwarf companions around a solar-type star with a contrast ▵I~12 at 2 and with no use of any
coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has
been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini,
Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and
disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some
perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge
this is the first time that high contrast considerations are included in optical speckle imaging approach.
Lucky imaging techniques implemented by the FastCam group (see http://www.iac.es/proyecto/fastcam/) at the Instituto
de Astrofisica de Canarias have demonstrated its ability to obtain spectacular diffraction limited images in telescopes
ranging from 1 to 4.2 m in visible wavelengths (mainly in the I band), at the expense of using only a small percentage of
the available images. This work presents the development of a real-time processor, FPGA-based, capable of performing
all the required processing involved in the lucky imaging technique: Bias and flat-field correction, quality evaluation of
images, quality threshold for image selection, image recentering and accumulation, and finally sending through Gigabit
Ethernet both raw and processed images to a PC computer. Furthermore, a real time display is generated directly from
FPGA showing both types of images, plus a histogram of the computed quality values and the threshold used. All
processes can co-exist physically located in separated places inside the FPGA, using its natural parallel approach, and
can easily handle the 512x512 pixels at 30 fps found at the sensor camera output (an Andor Ixon+ DU-897ECSO
EMCCD). Flexibility and parallel processing features of the reconfigurable logic have been used to implement a novel
imaging strategy for segmented-mirror telescopes, allowing separate evaluation of every segment and posterior
accumulation to achieve the resolution limit of a single segment with the integration capability of the full primary mirror.
FastCam is an instrument jointly developed by the Spanish Instituto de Astrofísica de Canarias and the Universidad Politécnica de Cartagena designed to obtain high spatial resolution images in the optical wavelength range from ground-based telescopes.
The instrument consists of a very low noise and very fast readout speed EMCCD camera capable of reaching the diffraction limit of medium-sized telescopes from 500 to 850 nm. FastCam incorporates a FPGAs-based device to save and evaluate those images minimally disturbed by atmospheric turbulence in real time. The undisturbed images represent a small fraction of the observations. Therefore, a special software package has been developed to extract, from cubes of tens of thousands of images, those with better quality than a given level. This is done in parallel with the data acquisition at the telescope.
After the first tests in the laboratory, FastCam has been successfully tested in three telescopes: the 1.52-meter TCS (Teide Observatory), the 2.5-meter NOT, and the 4.2-meter WHT (Roque de los Muchachos Observatory). The theoretical diffraction limit of each telescope has been reached in the I band (850 nm) -0.15, 0.08 and 0.05 arcsec, respectively-, and similar resolutions have been also obtained in the V and R bands.
Future work will include the development of a new instrument for the 10.4-meter GTC telescope on La Palma.