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At present, new approaches for the use of drones in high-precision optical applications are rising, especially with those known as multirotor. However, the optical turbulence effects generated by multirotor drones are not entirely understood. These optical effects can reduce the performance of the optical instruments that they transport. We present measurements of the wavefront deformation generated by the temperature fluctuations and the airflow of a drone’s propulsion system. To do so, we used a single arm of a DJI S800 EVO Hexacopter (professional drone) and measured its operating temperature with a commercial infrared camera. The resulting temperature variation, between a switched-off propulsion system at room temperature and one running at its maximum performance, was 34.2°C. Later, we performed two different interferometric tests: Takeda’s method and the phase-shifting technique, using a ZYGO interferometer. These tests show that the total deformation over an incident wavefront to the propeller airflow is lower than 0.074 λ PV and 0.007 λ RMS (HeNe laser, λ = 633 nm). We determine that the optical turbulence produced by a drone propulsion system is negligible.

We propose a passive indirect light collector system for interior lighting with the use of diffuse reflectors. This system is based on the idea that diffuse reflectors may increase the acceptance angle of passive systems therefor improving the overall effectiveness and also achieving a better response to light directionality in certain hours of the day. We search the most efficient way to collect optical power by scaling the collection area with a multi-level configuration. We also analyse the light collection on buildings facades through the simulation of the behaviour of the system under cloudy day conditions showing these systems as a feasible and economic option for indirect and direct light collection for interior lighting, allowing a less invasive way to conduct light to interiors with acceptable efficiency and avoiding the use of heliostats or expensive coating materials.

COATLI is a new instrument and telescope that will provide 0.3 arcsec FWHM images from 550 to 920 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited imager. The imager has a steering mirror for fast guiding, a blue channel using an EMCCD from 400 to 550 nm to measure image motion, a red channel using a standard CCD from 550 to 920 nm, and an active optics system based on a deformable mirror to compensate static aberrations in the red channel. Since the telescope is small, fast guiding will provide diffraction-limited image quality in the red channel over a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the Observatorio Astronomico Nacional in Sierra San Pedro Martir, Baja California, Mexico, in 2016 and will initially operate with a simple interim imager. The definitive COATLI instrument will be installed in 2017. In this work we present the general optomechanical and control electronics design of COATLI.

FRIDA will be a near infrared imager and integral field spectrograph covering the wavelength range from 0.9 to 2.5 microns. FRIDA will work in two observing modes: direct imaging and integral field spectroscopy. This paper presents the main structure of the FRIDA mechanisms control system. In order to comply with a high level of re-configurability FRIDA will comprise eight cryogenic mechanisms and one room temperature mechanism. Most of these mechanisms require high positioning repeatability to ensure FRIDA fulfills with high astronomical specifications. In order to set up the mechanisms positioning control parameters a set of programs have been developed to perform several tests of mechanisms in both room and cryogenic environments. The embedded control software for most of the FRIDA mechanisms has been developed. A description of some mechanisms tests and the software used for this purpose are presented.

We present a real-time, fully automated method to remove instrumental signatures from stellar scintillation images. The method was developed in connection with the Low Layer SCIDAR (Scintillation Detection and Ranging) (LOLAS), an instrument dedicated to the measurement of atmospheric optical-turbulence profiles, , in the first kilometre of altitude, with high altitude-resolution. By examining the scintillation images and their correlation maps we evaluate, and then correct, image deficiencies typical of a portable telescope, such as defocus, image movement, field rotation and tracking errors, prior to processing according to the SCIDAR technique. In addition, detector spreading noise is corrected for, and flux variations caused by clouds or fog are monitored. The efficiency of the methods is demonstrated by comparing double-star scintillation autocorrelations obtained with and without the use of the self-adjusting procedures. Applying those stabilization methods, LOLAS was successfully exploited to characterize the vertical profiles along the lower layer on top of Mauna Kea Observatory.

We present the design concept and validation of a cryogenic lens mount for a noncemented doublet for the near-infrared diffraction limited instrument FRIDA. The design uses an autocentering mount that maintains the relative alignment of the lenses, acting against any displacement that may be induced by external forces by automatically returning the lenses to their nominal positions. Autocentering techniques have been used for instruments at room temperature with relatively relaxed image quality requirements. We present in detail its application to a mount for a cryogenic instrument working at the diffraction limit. The design has been tested on the collimator of FRIDA, a noncemented doublet of CaF2 and S-FTM16. We describe the alignment requirements of the system, and we show the calculations that ensure that the lenses will suffer both appropriate stresses and temperature differences. We present the experimental validation of a prototype, demonstrating that the design delivers an excellent performance without inducing unnecessary stresses on the optical components, provided that the lenses are previously aligned with very high precision.

Curvature wavefront sensors obtain the wave-front aberrations from two defocused intensity images at each side of the pupil plane. Typically, when high modulation speeds are required, as it is the case with Adaptive Optics, that defocusing is done with a fast vibrating membrane mirror. We propose an alternative defocusing mechanism based on an electrowetting variable focus liquid lens. The use of such lenses may perform the required focus modulation without the need of extra moving parts, reducing the overall size of the system.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias (GTC)) is designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy capabilities with low, intermediate and high (R ~ 30,000) spectral resolutions, to operate in the wavelength range 0.9 – 2.5 μm. The integral field unit is based on a monolithic image slicer and the imaging and IFS observing modes will use the same Teledyne 2Kx2K detector. FRIDA will be based on a Nasmyth B of GTC, behind the adaptive optics (AO) system. The key scientific objectives of the instrument include studies of solar system bodies, low mass objects, circumstellar outflow phenomena in advanced stages of stellar evolution, active galactic nuclei high redshift galaxies, including resolved stellar populations, semidetached binary systems, young stellar objects and star forming environments. FRIDA subsystems are presently being manufactured and tested. In this paper we present the challenges to perform the verification of some critical specifications of a cryogenic and diffraction limited NIR instrument as FRIDA. FRIDA is a collaborative project between the main GTC partners, namely, Spain, Mexico and Florida.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a cryogenic and diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS). Both, the imaging mode and IFS observing modes will use the same Teledyne 2Kx2K detector. This instrument will be installed at Nasmyth B station, behind the GTC Adaptive Optics system (GTCAO). FRIDA will provide the IFS mode using a 30 slices Integral Field Unit (IFU). This IFU design is based on the University of Florida FISICA where the mirror block arrays are diamond turned on monolithic metal blocks. The FRIDA IFU is of the slicer type; conformed mainly by 3 mirror blocks with 30 spherical mirrors each. It also has a Schwarzschild relay based on two off axis spherical mirrors and an afocal system of two parabolic off axis mirrors. Including two insertion mirrors the IFU holds 96 metal mirrors. All the mirrors have been manufactured by diamond turning techniques on monolithic blocks of aluminum 6061-T6 coated by a Nickel alloy. Except for the Schwarzschild relay and the insertion mirrors, 92 mirrors were manufactured by Corning in Keene NH, USA. The different blocks and mirrors are mounted on an opto-mechanical support that ensures the image quality and integrity of the complete IFU. In this work advances on the manufacturing of the FRIDA IFU components are described. Furthermore, the mirror blocks individual verification tests and are also described.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a cryogenic and diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS). Both, the imaging mode and IFS observing modes will use the same Teledyne 2Kx2K detector. This instrument will be installed at Nasmyth B station, behind the GTC Adaptive Optics system (GTCAO). FRIDA will provide the IFS mode using a 30 slices Integral Field Unit (IFU). This IFU design is based on University of Florida FISICA where the mirror block arrays are diamond turned on monolithic metal blocks. FRIDA IFU is conformed mainly by 2 mirror blocks with 30 spherical mirrors each. The image slicing is performed by a block of 30 cylindrical mirrors each of 400 μm width. It also has a Schwarzschild relay based on two off axis spherical mirrors that adapts the GTCAO corrected PSF to the slicer mirrors dimensions. To readapt the sliced PSF to the spectrograph input numerical aperture the IFU has an afocal system of two parabolic off axis mirrors. The AO PSF is bigger than the slice mirror dimensions and this produces diffraction effects. These diffraction effects combined with the intrinsic IFU and spectrograph aberrations produce the final instrumental PSF of the IFS mode. In order to evaluate the instrumental PSF quality of the FRIDA IFS, modeling simulations were performed by the ZEMAX Physical Optics Propagation (POP) module. In this work the simulations are described and the PSF quality and uniformity on a reconstructed IFS image is evaluated. It is shown the PSF quality of the IFS mode including the instrument manufacturing tolerances fulfills the specifications.

FRIDA will be a near infrared imager and integral field spectrograph covering the wavelength range from 0.9 to 2.5 microns. Primary observing modes are: direct imaging and integral field spectroscopy. This paper describes the main advances in the development of the electronics and control system for both the mechanisms and house-keeping of FRIDA. In order to perform several tests of mechanisms in both room and cryogenic environments, a set of programs had been developed. All variables of the vacuum control system were determined and the main control structure based on one Programmable Logic Controller (PLC) had been established. A key function of the FRIDA’s control system is keeping the integrity of cryostat during all processes, so we have designed a redundant heating control system which will be in charge of avoiding cryostat inner overheating. In addition, some improvements of cryogenic and room temperature cabling structure are described.

The nulling coronagraph, first proposed by Roddier and Roddier, uses a small mask (less than half the size of the central Airy spot) that shifts the phase of the incoming light by 180° to strongly attenuate the Airy spot as well as the rings. We report on both theoretical and laboratory performance. In our laboratory experiment, we reduce the peak intensity of the Airy pattern by a factor of 16. We derive estimates of the performance of a nulling coronagraph used on a telescope equipped with an adaptive optics system, based upon the performance of the University of Hawaii Hokupa'a adaptive optics system. On a 3.6 m telescope at 1.65 μm, it is found that a tip/tilt amplitude lower than 20 mas is needed for such a coronagraph to yield an extinction better than 2 stellar mag.

FRIDA has been conceived as the first science instrument for the adaptive optics system of the Gran Telescopio Canarias (GTC). It is designed to be installed at the Nasmyth A platform, behind the GTC adaptive optics system. FRIDA will be a diffraction limited, near infrared imager and integral field spectrograph sensitive from 0.9 to 2.5 μm. It may also include provisions for future upgrades such as coronographic masks and long slits. FRIDA is a collaborative project between the Instituto de Astronomia, UNAM, Mexico, the Instituto de Astrofisica de Canarias, Spain, and the Astronomy Department of the University of Florida, USA.

FRIDA will be a common-user near infrared imager and integral field spectrograph covering the wavelength range from 0.9 to 2.5 microns. Primary observing modes driven the instrument design are two: direct imaging and integral field spectroscopy. FRIDA will be installed at the Nasmyth-B platform of the Gran Telescopio Canarias (GTC) behind the GTC Adaptive Optics (GTCAO) system. Instrument will use diffraction-limited optics to avoid degrading the high Strehl ratios derived by the GTCAO system in the near infrared. High-performance astronomical instruments with a high reconfiguration degree as FRIDA, not only depends on optical and mechanical efficient designs but also on the good quality of its electronics and control systems design. In fact, astronomical instruments operating performance on telescope greatly relies on electronics and control system. This paper describes the main design topics for the FRIDA electronics and mechanisms control system, pointing on the development that these areas have reached on the project status. FRIDA Critical Design Review (CDR) was held on September 2011.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a cryogenic and diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS). Both, the imaging mode and IFS observing modes will use the same Teledyne 2Kx2K detector. This instrument will be installed at Nasmyth B station, behind the GTC Adaptive Optics system. FRIDA will provide the IFS mode using a 30 slices Integral Field Unit (IFU). This IFU design is based on University of Florida FISICA where the mirror block arrays are diamond turned on monolithic metal blocks. FRIDA IFU is conformed mainly by 3 mirror blocks with 30 spherical mirrors each. It also has a Schwarzschild relay based on two off axis spherical mirrors and an afocal system of two parabolic off axis mirrors. Including two insertion mirrors the IFU holds 96 metal mirrors. Each block or individual mirror is attached on its own mechanical mounting. In order to study beam interferences with mechanical parts, ghosts and scattered light, an iterative optical-mechanical modeling was developed. In this work this iterative modeling is described including pictures showing actual ray tracing on the opto-mechanical components.

Circular phase mask concepts represent promising options for high contrast imaging and spectroscopy of exo-planets. Depending on their design, they can either work as a diffraction suppression system or as a focal plane wavefront sensor. While the apodized Roddier coronagraph uses a π-phase mask to obtain complete suppression of the star image in monochromatic light, the Zernike sensor uses a π/2-phase mask to measure the residual aberrations in the focal plane by encoding them into intensity variations in the relayed pupil. Implementations of the Zernike sensor can be considered in exoplanet imagers such as VLT-SPHERE, Gemini planet imager, Palomar-P1640 or Subaru-SCExAO to enlarge their capabilities. However, such concepts have not been validated experimentally up to now. Our goal is to perform lab demonstration of this concept on our visible coronagraph testbed at LAM and to propose an upgrade design for SPHERE. In this communication, we report on results of lab measurements of the Zernike sensor and determine its sensitivity to small wavefront errors.

The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS, a near-infrared multi-object echelle spectrograph operating at spectral resolution R=20,000 over the 1-2.5 mu m bandpass) was selected in 2010 by the Gran Telescopio Canarias (GTC) partnership as the next-generation near-infrared spectrograph for the world's largest optical/infrared telescope, and is being developed by an international consortium. The MIRADAS consortium includes the University of Florida, Universidad de Barcelona, Universidad Complutense de Madrid, Instituto de Astrofisica de Canarias, Institut de Fisica d'Altes Energies, Institut d'Estudis Espacials de Catalunya and Universidad Nacional Autonoma de Mexico, as well as probe arm industrial partner A-V-S (Spain). In this paper, we review the overall system design for MIRADAS, as it nears Preliminary Design Review in the autumn of 2012.

Stellar coronagraphs using circular phase masks are promising concepts dedicated to the image suppression of an observed bright star in order to enhance the substellar mass companions present in its vicinity, typically 2 λ/D angular separation. These concepts include a focal plane phase mask which introduces a phase delay on a part of the stellar image. With an adequate choice of the mask parameters (thickness, diameter), the light going through the mask and the light going outside the mask will interfere destructively inside the geometric pupil in the following pupil plane. The light rejected outside this re-imaged pupil will be blocked by a Lyot stop. Typically, the mask physical size is about λF, where F denotes the f-number of the optical system, and the mask thickness depends on the required phase shifting. The contrast provided by these concepts is highly related to the quality of thickness profile of the phase mask and therefore, severe manufacturing tolerances are necessary to reach the theoretical performance of the corresponding coronagraphic system. In 2007, we designed a Roddier & Roddier phase mask with a 65 μm diameter and ordered it to GEPI of Paris Observatory which manufactured it using ion etching process. A roughness of 0.8 nm rms and a transition width of 1% of the mask diameter were measured with a profilometer for this mask showing the good quality of the mask (N'Diaye et al. 2010). We pursue our efforts to design and manufacture high quality masks in collaboration with the firm SILIOS. Several tests of manufacturing procedures are currently realized to reach the best trade-off between mask roughness and mask transition width. These values, measured in our laboratory with a profilometer, allow us to determine the best configuration for fabrication. In addition, by knowing the mask profile, we can estimate theoretically the performance that can be reached.

Stellar coronagraphy is a key technology for current and future instruments for exoplanet imaging and spectroscopy, both on the ground and in space. We pursue the research on coronagraphs based on circular phase masks and report in this paper on recent advances in terms of the trade between spectral bandwidth and achievable contrast. Circular phase masks combined with colored apodizations prove to be promising options in such coronagraphic systems to reach high contrast gains within the search area over a wide band of wavelengths.

International audience; Context. Coronagraphic techniques are required to observe substellar mass companions close to nearby bright stars by direct imagery. Phase mask coronagraphs are particularly interesting because they give access to the innermost regions. While the principle of the first such concept was validated experimentally a decade ago, the achieved brightness attenuation was too low to be conclusive, probably due to the imperfect thickness profile of the mask. Aims. We have manufactured and tested a second-generation Roddier & Roddier coronagraph in preparation for the development of more elaborate phase mask designs, planned to be used in the future European Extremely Large Telescope. Methods. A monolithic phase mask was made by ion beam machining. Experimentally obtained coronagraphic images were compared with simulated images. Results. Good agreement with theory was obtained. A peak attenuation of 216 was achieved, and a contrast of similar to 10(-5) was measured at 5.7 lambda/D. The results exploring contrasts obtained at different distances from the star for different mask dimensions are particularly interesting, confirming predictions made in the literature.

In response to an Announcement of Opportunity for new instrumentation for the Gran Telescopio Canarias (GTC) issued on October 2009, an international team led by the University of Florida and composed of scientists and engineers from 8 institutions in 3 countries submitted a proposal for building a highly powerful instrument within the required envelope and budget. The MIRADAS instrument will be a common user NIR multi object spectrograph equipped with a sophisticated multiplexing system (MXS) able to deliver spectral resolutions of R~20,000 in the wavelength range from 1 to 2.5 microns for up to 20 objects simultaneously sparsely distributed over a field of regard of 5 arcmin in diameter. In this paper, we summarize the main instrumental features of the proposed instrument which is under review by the GTC Project Office.

We describe diamond-turned material tests for the integral field unit (IFU) for the FRIDA instrument (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias). FRIDA is closely based on the design of the successful FISICA cryogenic infrared image slicing device, which used "monolithic" mirror arrays, diamond turned into single pieces of metal. FRIDA, however, will require better roughness characteristics than the 15nm RMS of FISICA to avoid light scatter in FRIDA's shorter wavelength limit (900nm). Al 6061 seems to be limited to this roughness level by its silicate inclusions so some new combination of materials that are compatible with FRIDA's Al 6061 structure must be found. To this end, we have tested six diamond-turned mirrors with different materials and different platings. We used the Zygo interferometer facility at IA-UNAM to do warm and cold profile measurements of the mirrors to investigate possible bimetallic deformation effects. We present a detailed comparison of the various performance characteristics of the test mirrors.

We describe progress in the construction of an adaptive optics system for the 2.1 meter telescope of the Observatorio Astronomico Nacional on Sierra San Pedro Martir, in Baja California, Mexico. The system will use a 19 element bimorph deformable mirror mounted on an articulated platform and a curvature wavefront sensor with natural guide stars. It will have two modes of operation. In adaptive optics mode, it is expected to give excellent correction above 1.0 μm and good correction down to 0.6-0.9 μm, depending on the seeing, although the sky coverage will be limited. In fast guiding mode, the system should give images at or better than the excellent natural seeing of the site and have much greater sky coverage. The system is currently undergoing laboratory testing.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS) capabilities with low, intermediate and high spectral resolutions to operate in the wavelength range 0.9 - 2.5 μm. The integral field unit is based on a monolithic image slicer based on the University of Florida FISICA. Both, the imaging mode and IFS observing modes will use the same Rockwell 2K×2K detector. FRIDA will be based at a Nasmyth focus of GTC, behind the GTCAO system. The FRIDA optical design, stray light analysis, tolerance analysis and manufacturing feasibility are described in this contribution.

FRIDA will be an Infrared Imager and an Integral Field Spectrograph (IFS) for the 10 .4 m Gran TelescopioCanarias (GTC). This instrument is scheduled to be installed in 2010, at the Nasmyth A platform of the GTC,behind GTCAO (the Adaptive Optics [AO] system of the GTC). FRIDA design incorporates straightforwardupgrade paths for focal plane masks. In this work, we analyze the capability of FRIDA to provide high dy-namic range images. Dierent coronagraphic con“gurations could be inserted within FRIDA optical assembly.We quantify numerically their performance in presence of AO compensated wavefronts. Thereafter, numericalsimulations about the Simultaneous Spectral Dierential Imaging 1 (SSDI) method are presented. This techniqueaims to suppress the AO residual speckles and can be applied to selected frames of the data cube, provided byFRIDA in IFS mode. Therefore, we estimate the starlight attenuation that could be reached with the associationCoronagraph + SSDI methodŽfor the ground-based instrument GTC + GTCAO + FRIDAŽ.Keywords: high angular resolution, coronagraphy, adaptive optics, image processing

The reconstruction quality of turbulence-induced phase distortions from Hartmann data is calculated for masks with different subpupil forms by means of computer simulations. Four subpupil forms are considered: the circle, the square, the hexagon, and the polar segment. We show that, for the case of a circular aperture, the mask with polar segment subpupils provides the best reconstruction quality.

The influence of the turbulence outer scale on the Strehl ratio obtained with low-order adaptive optics systems is examined by numerical simulation. The Karhunen–Loeve approach is used to generate wave-front samples. A method that allows construction of the outer-scale-dependent Karhunen–Loeve functions is described. It is shown that the Strehl ratio produced by a second-order adaptive optics correction (tip–tilt, defocus, and astigmatism) is affected quite strongly by the finite outer scale. For the higher-order correction, the effect under study is weak and appears only when the outer-scale magnitude becomes less than the aperture diameter. It is also shown that the finite outer scale has a positive effect on the Strehl ratio of the uncorrected long-exposure image.

FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field spectroscopy (IFS) capabilities with low, intermediate and high spectral resolutions to operate in the wavelength range 0.9 - 2.5 μm. The integral field unit is based on a monolithic image slicer and the imaging and IFS observing modes will use the same Rockwell 2Kx2K detector. FRIDA will be based at a Nasmyth focus of GTC, behind the AO system. The main design characteristics of FRIDA are described in this contribution. FRIDA is a collaborative project between the main GTC partners, namely, Spain, Mexico and Florida, lead by UNAM.

GUIELOA is a Curvature type Adaptive Optics system for the 2.1 m San Pedro Martir Telescope. It performs a bimorph 19 actuators deformable mirror and a 19 lens-let array for the wave-front sensor (WFS). GUIELOA corrects effectively the first 8 Zernike polynomials of the aberrated wave-front produced by the atmospheric turbulence. For the closed loop control it performs two SPARC FORCE 5 SBC computers working in concert. The lens-let array + optical fibers send the light from defocused pupil images to 19 avalanche photo-diodes. In this work it is shown how the lens-let array was manufactured at IAUNAM with CIDESI and Centro de Investigaciones en Optica (CIO).

In March 2004 was accepted in the site of Gran Telescopio Canarias (GTC) in La Palma Island, Spain, the Commissioning Instrument (CI) for the GTC. During the GTC integration phase, the CI will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature Wave-front sensing (WFS), and high resolution Shack-Hartmann WFS. This instrument was built by the Instituto de Astronomia UNAM in Mexico City and the Centro de Ingenieria y Desarrollo Industrial (CIDESI) in Queretaro, Qro under a GRANTECAN contract after an international public bid. Some optical components were built by Centro de Investigaciones en Optica (CIO) in Leon Gto and the biggest mechanical parts were manufactured by Vatech in Morelia Mich. In this paper we made a general description of the CI and we relate how this instrument, build under international standards, was entirely made in Mexico.

SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida, United States, Series: Proceedings of SPIE; no. 6269

Under a contract with the GRANTECAN, the Commissioning Instrument (CI) is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. The CI will verify the Gran Telescopio Canarias (GTC) performance during the commissioning phase between First Light and Day One. The design phase is now completed and the project is currently in the manufacturing phase. The CI main goal is to measure the telescope image quality. To obtain a stable high resolution image, the mechanical structures should be as rigid as possible. This paper describes the several steps of the conceptual design and the Finite Element Analysis (FEA) for the CI mechanical structures. A variety of models were proposed. The FEA was useful to evaluate the displacements, shape modes, weight, and thermal expansions of each model. A set of indicators were compared with decision matrixes. The best performance models were subjected to a re-optimization stage. By applying the same decision method, a CI Structure Model was proposed. The FEA results complied with all the instruments specifications. Displacements values and vibration frequencies are reported.

This paper describes both the electronics design (ED) and the acceptance control system (ACS) of the Commissioning Instrument (CI) for the Gran Telescopio Canarias (GTC). The CI mainly comprises ten mechanisms accurately positioned by control algorithms, which in turn are programmed according to the CI operation modes. The control system is based on a CANopen protocol and is completely compatible with the GTC control system. CANopen is a serial communication protocol based on CAN bus. The CANopen features allow for the control system high reliability. A Reliability, Availability, Maintainability, and Safety (RAMS) analysis was carried out to guarantee the CI opto-mechanics and electronics performance.

Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. This paper will discuss in some detail the final Commissioning Instrument (CI) mechanical design and fabrication. We will also explain the error budget and the barrels design as well as their thermal compensation. The optical design and the control system are discussed in other papers. The CI will just act as a diagnostic tool for image quality verification during the GTC Commissioning Phase. This phase is a quality control process for achieving, verifying, and documenting the performance of each GTC sub-systems. This is a very important step for the telescope life. It will begin on starting day and will last for a year. The CI project started in December 2000. The critical design phase was reviewed in July 2001. The CI manufacturing is currently in progress and most parts are finished. We are now approaching the factory acceptance stage.

The aim of this study was to evaluate the efficacy of cefuroxime, compared with the combination of dicloxacillin/chloramphenicol, for the treatment of children with parapneumonic pleural effusion or empyema. Forty patients, aged 3 months to 5 years, with pleural effusion or empyema were randomized to receive cefuroxime (100 mg/kg/day) IV (n=20) or chloramphenicol (100 mg/kg/day) plus dicloxacillin (200 mg/kg/day) IV (n=20). Both groups were similar in age, days of illness, clinical and radiological findings, and etiology. Most patients (70%) had an empyema at presentation. There was no difference in clinical outcomes, including days to defervescence, duration of respiratory distress, duration of chest tube drainage, and days to discharge from hospital. The complication rates were similar in both groups. Pleural thickening occurred in four patients, bronchopleural fistula in two, and loculated empyema in one patient of each treatment group. Adverse effects attributed to cefuroxime were mild and infrequent. These results suggest that cefuroxime is an effective and well-tolerated alternative for the treatment of children with pleural effusion and empyema.

The applicability of the curvature method for co-phasing of segmented mirrors is investigated by means of simulations for the case of strongly defocused images. The simulations are performed for both the monochromatic and the white light as well. A simple wavefront reconstruction from curvature signal was made. The reconstruction quality of the piston modes and the aberrations up to the fourth order is analyzed. The dependence of the Central Intensity Ratio for a segmented mirror as a function of the rms segment's aberrations is presented. The effect of turbulence-induced distortions on the quality of mirror co-phasing is analyzed. It is shown that the local pistons and the local tip-tilts can be measured directly from the curvature signal without any phase recovering procedure. The results obtained show that, even in the presence of the atmospheric turbulence, the curvature method is sensitive enough to detect the errors of segmented mirrors.

We demonstrate that the curvature equation can be modified using some properties of Distributions theory for segmented mirror techniques. It is shown that, additionally to the individual segment aberrations, the modified equation contains the information about the relative pistons and tip- tilts among the segments. The validity of the equation is verified by numerical simulations and by a laboratory experiment as well.

We have obtained the curvature signal from defocused images before and after the pupil image for a simplified segmented mirror model. We used white light interferometry in order to calibrate the relative piston difference between the segments. The first results of applying the Curvature Sensing method to measure this relative piston difference are presented.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A detailed analysis of anisotropy in the point spread function (PSF) associated with off-axis adaptive astronomicalcorrection is presented. The results obtained are based on the experimental C profile which has been recentlymeasured at San Pedro Martir observatory (Mexico). it is found that the PSF has a complicated shape that dependsstrongly on the wavelength and on the separation between the guide and observed stars.Keywords: Atmospheric Turbulence, Adaptive Optics High Angular Resolution Techniques, Telescopes 1 . INTRODUCTION It has been found recently both experimentally' and theoretically2 as well that the point spread function (PSF)associated with off-axis adaptive correction is anisotropic. This effect can induce quite strong distortions in wide-field images obtained with astronomical adaptive systems, so one needs to use some post-processing technics forthe image restoration. However in order to perform a successive image restoration, it is desirable to know the PSF

The performance of adaptive optics systems not only depends on its number of actuators and optics quality but also on the performance of the controller used to compensate the wave- front distortions. Due to the temporal bandwidth required to realize a suitable tracking of the atmospheric turbulence dynamics it is necessary that the controller have a short time delay and high stability and robustness indices. A fuzzy logic controller, a technique related with Artificial Intelligence, accomplish all the characteristics aforementioned. In this paper, we present some laboratory tests with the LOLA adaptive optics tip-tilt system in closed loop with a fuzzy controller. In addition, we present some results obtained with LOLA and fuzzy control at the 1 meter Telescope of the Observatorio Astronomico Nacional in Tonantzintla, Peubla, Mexico. We analyze these results with a signal analysis approach such as the power spectrum of the image centroid motion and its correspondent residual variance.

Atmospheric turbulence distorts the wavefront of the incoming light from an astronomical object and so limits the ability of a telescope to form a perfect image. The AO systems for astronomy had come the most powerful tool for infrared observation in the near thermal domain. A conventional AO system requires quite a few reflections that are needed to transfer and correct an image. A typical system would have a collimator, deformable mirror and a camera at the bare minimum. For the thermal region the gains are substantial where one can eliminate extra optical surfaces and their associated thermal background, that occurs when you put the deformable mirror at the secondary. We study the possibility of development an adaptive secondary with the techniques of a Current Bimorph mirror with the necessaries number of actuators for control the edge slope. Also we simulate the performance of a 19 channels curvature adaptive optics system in order to demonstrate the gain achievable with an adaptive secondary. The adaptive secondary for the 2.1 m Telescope at SPM Observatory is designed for a f/50 beam, 100 mm in diameter with 19 actuators necessaries to control the edge slope and curvature.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The University of Mexico 6.5m TIM telescope project has a 19 fully active segmented M1 and an active M2. Each 1.8m segment is a relative thin meniscus supported by three position hard points, computer controlled, and 16 force soft actuators which support the meniscus and can deform it. This project includes an AO system using a corrector mirror placed at a conjugated telescope pupil. We decided to specify the telescope optics in function of this AO system from the beginning and not specify the AO system in function of the telescope. In order to calculate the optical budget of the TIM we simulated, using a Monte Carlo technique e approach, the Strehl ratio of the telescope PSF as a function of the low order aberration values of the individual segments. The low order aberrations studied are the 'position' aberrations, as the piston and the tip-tilt between the segments, and the 'deformation' aberrations as the values for the deformation aberrations for each segment are comparable with the 'intrinsic' quality of the primary mirror of an active telescope as the NTT or our recently enhanced 2.1m UNAM telescope, if diffraction limited imaging for the complete primary is specified. This result shows that the technology for a correct support for the individual segments actually exist. The results obtained are used for the optical quality definition of the TIM 6.5m telescope.

The influence of the turbulence outer scale on the power spectrum (PS) of speckle interferograms and on the Strehl ratio obtained with low-order adaptive optics (AO) system is examined by numerical simulation. It is shown that the outer scale has a little positive effect the PS when the outer scale magnitude becomes less than the aperture diameter. The finite outer scale has a positive effect on the STrehl ratio of the uncorrected long-exposure image. It is also shown that the Strehl ratio produced by a second-order AO correction is affected quite strongly by the finite outer scale. For the more higher-order correction, the effect under study is very weak and it appears only when the outer scale magnitude becomes less than the aperture diameter.

We present the Mexican Infrared-Optical New Technology Telescope Project (TIM). The design and construction of a 7.8 m telescope, which will operate at the Observatorio Astronomico Nacional in San Pedro Martir, B.C. (Mexico), are described. The site has been selected based on seeing and sky condition measurements taken for several years. The f/1.5 primary mirror consists of 19 hexagonal off-axis parabolic Zerodur segments. The telescope structure will be alt-az, lightweight, low cost, and high stiffness. It will be supported by hydrostatic bearings. The single secondary will complement a Ritchey-Chretien f/15 design, delivering to Cassegrain focus instrumentation. The telescope will be infrared optimized to allow observations ranging from 0.3 to 20 microns. The TIM mirror cell provides an independent and full active support system for each segment, in order to achieve both, phasing capability and very high quality imaging (0.25 arcsec).

Optical testing of the 2.1-m telescope in San Pedro Martir, Observatorio Astronomico Nacional de Mexico, by the methods of wavefront curvature sensing and bi-Ronchi analysis, has shown that the telescope suffered of large amounts of astigmatism. We identified these as due to improper primary mirror support and developed an active control system to correct for it. The number and position of the actuators were decided in accordance to the flexural modes that needed to be corrected, resulting in a system of 18 pressure controlled pneumatic actuators, with an outer loop that verifies the load at three hard points. A PID algorithm and matrix inversion are fundamental parts of this outer loop, that guarantees that the M1 mirror is tilted as a rigid body to maintain it properly aligned. The successful performance of the system to correct low order aberrations is reported.

Differential speckle interferometry is based on the cross analysis of series of speckle patterns produced in different wavelengths. The study of the position differences between these speckles provides angular information on objects much smaller than the diffraction limit. In order to make the measurements of the photocenter displacement, we have built an instrument which behaves like a spectrograph in one direction and a speckle interferometer in the perpendicular direction. A mirror anamorphoser permits us to meet the different sampling requirements. The dispersed speckle pattern is recorded by a photon counting camera. The measurements of the photocenter displacements are very sensitive to differences of aberration between spectral channels and temporal variations of the detector's distorsion. Our instrument provides images with a quality equal to the diffraction limit plus residual aberrations of the order of one hundreth of the wavelength used. The distorsion of the optics is much smaller than the size of the temporal variations of the detector's distorsion. In order to correct this variable distorsion, spatial and spectral modulations are made in a fully automated instrument.

We have designed and installed a new set of actuators for the suspension of the primary mirror of the 2.1-m telescope at San Pedro Mártir. This active optics system has allowed us to correct low-order aberrations identified by several wave-front analysis techniques.

The outer-scale influence on spatial and temporal characteristics of turbulence-induced wave-front distortions is discussed. The calculation results for the image centroid and the Zernike modes are presented. Two methods of the outer-scale estimation based on tilt and defocus and on image centroid measurements are suggested. The application of the results obtained to adaptive optics problems is considered. Finally, a possibility of prediction of the wave-front statistical characteristics is discussed.

A star image is reconstructed by referring to specklegrams of a widely separated star. It is shown that high-resolution imaging is feasible using a reference star that is wider separated than an isoplanatic angle. Stellar imaging based on a simple adaptive-optics scheme is investigated.