New hydrodynamic improvements have been developed in order to enable pulsed polishing with the HyDRa system. The operational parameters of the tool are not affected by these modifications, i.e., tool bias and the tool’s floating capability are not lost, and a linear erosion function is produced. The minimum removal is no longer ruled by maximum computer numerical control speed, allowing for high-precision removal that can be taken from zero to the maximum attainable of the tool, in minimum increments of 3.5 nm / ms. This modification also improves the convergence rate of the polishing process toward the desired surface. This development guarantees a high-speed, pulsed operation that enables the tool to be used in a variety of polishing modes, ranging from discrete pixel to continuous pulse width modulation (PWM) polishing. This new capability opens a wide range of applications that can now be tackled with the system, such as zonal and tessellated polishing. PWM capability also allows for simultaneous, multi-head polishing of large optical surfaces.
In this work we present a simulation of the wave-front sensing of the active primary mirror support for the 2.1-m telescope of the San Pedro Mártir's Observatory by Non-Linear Curvature Wave-front Sensing. The active cell is going to be tested by changing its actuator values. In each active cell state, defocused pupil images from both sides of the focal plane will be simulated and phase retrieval will be performed. The algorithm employed to reconstruct the wave-front will be discussed, as well as the sensitivity obtained in our simulation.
A wave-front coded imaging system is an optical-digital method for aberration control. Wave-front coding technology incorporates an aspheric element in the optical system in order to capture a coded image and by digital processing decode it to obtain the final image. The WFC system is very insensitive to defocus-like aberrations and thereby becomes a tool in the aberration balancing for telescope systems. We propose WFC technology to be implemented in a two spherical mirror telescope. In this work we present the design and simulation of the proposed telescope, trade-offs encountered in the design process and aspects of the image restoration.
The Reionization and Transients InfraRed camera (RATIR) is a simultaneous optical/NIR multi-band imaging
camera which is 100% time-dedicated to the followup of Gamma-ray Bursts. The camera is mounted on the
1.5-meter Johnson telescope of the Mexican Observatorio Astronomico Nacional on Sierra San Pedro Martir in
Baja California. With rapid slew capability and autonomous interrupt capabilities, the system will image GRBs
in 6 bands (i, r, Z, Y, J, and H) within minutes of receiving a satellite position, detecting optically faint afterglows
in the NIR and quickly alerting the community to potential GRBs at high redshift (z>6-10). We report here
on this Spring's first light observing campaign with RATIR. We summarize the instrumental characteristics,
capabilities, and observing modes.
Alan Watson, Michael Richer, Joshua Bloom, Nathaniel Butler, Urania Ceseña, David Clark, Enrique Colorado, Antolín Córdova, Alejandro Farah, Lester Fox-Machado, Ori Fox, Benjamín García, Leonid Georgiev, J. Jesús González, Gerardo Guisa, Leonel Gutiérrez, Joel Herrera, Christopher Klein, Alexander Kutyrev, Francisco Lazo, William Lee, Eduardo López, Esteban Luna, Benjamín Martínez, Francisco Murillo, José Manuel Murillo, Juan Manuel Núñez, J. Xavier Prochaska, José Luís Ochoa, Fernando Quirós, David Rapchun, Carlos Román-Zúñiga, Gennady Valyavin
The Reionization And Transients Infra-Red (RATIR) camera is intended for robotic operation on the 1.5-meter Harold
Johnson telescope of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
This paper describes the work we have carried out to successfully automate the telescope and prepare it for RATIR. One
novelty is our use of real-time absolute astrometry from the finder telescopes to point and guide the main telescope.
J. Manuel Nuñez, Eduardo de la Fuente, Esteban Luna, Joel Herrera, Enrique Velazquez, Fernando García, Eduardo López, Jorge Váldez, Benjamín García, Benjamín Martínez, Gerardo Guisa, Fernando Quiroz, Enrique Colorado, José Luis Ochoa, Jaime Almaguer, Arturo Chávez
We present the results of the optical characterization of the mirrors of the telescope of 62cm observatory "SEVERO
DIAZ GALINDO" property of the University of Guadalajara. We use the Ronchi test and a spherometer to measure by
first time, the radius of curvature for the primary and secondary mirror, the parameters of the telescope system were
obtained by using the commercial software ZEMAX. We confirm that both mirrors are adequate to work in the telescope
configuration and to do optical astronomy.
We present a new method for testing an optical surface. It uses the Ronchi test with variable-frequency rulings and a liquid-crystal display. The rulings can be formed by substructuring the spacing of a Ronchi ruling or combining several classical Ronchi rulings in a single variable-frequency ruling. This change allows us to observe smaller defects on the surface, because it enlarges the spatial-frequency domain of the ruling, and a larger dynamic range of detection of the Ronchi test can be obtained instead of increasing the resolution of the detection of the Ronchi test by iteratively changing classical Ronchi rulings with higher line density. As a result, we have found that it is possible to measure defects on a optical surface that are of size 57 nm (/11).
ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observatory at San
Pedro Martir, Baja California, Mexico. It has been developed by the Instituto de Astronomia of the Universidad
Nacional Autonoma de Mexico (IA-UNAM). The main goal of this instrument is to modernize the capabilities
of making science with that particular telescope. It is planned to achieve a spectral resolution between 500 and
5000. ESOPO is split into two arms; each one specialized in a specific wavelength range covering together all the
visible light. A very important issue in spectrographs is to avoid inside thermal gradients. Different temperatures
in the optical elements produce mechanical movements and image quality degradation during an exposition. The
error budget analysis developed for ESOPO allows establishing the required limits for temperature gradients. In
this paper is described the thermal analysis of the spectrograph, including specifications, finite element models,
thermal equations and expected thermal gradients.
The structure of the spectrograph ESOPO is the stiff mount that will maintain fixed all optics elements, electronics and
mechanical subsystems. The ESOPO spectrograph is a project of the "Instituto de Astronomia de la Universidad
Nacional Autonoma de Mexico" (IAUNAM) to upgrade its 2.1m telescope as a competitive facility for the next decade.
The scientific purpose is to obtain a modern high efficient intermediate-low dispersion spectrograph optimized for the
3500 - 9000 Å spectral interval with a spectral resolution of 500 ≤ R ≤ 5000. It is to be used at the cassegrain f/7.5 focus
of the 2.1 m telescope for general astronomical purposes. This work presents the mechanical design process and the form
in which the structure was verified to comply with the ESOPO's top level image quality and stability requirements. The
latter was not a lineal process. The way we resolved it is to run FEAs on the complete system and with the instrument in
different operation positions during a normal cycle of observations. These results are validated through the error budget
of the ESOPO. The structure is currently under construction.
This work presents the specifications, requirements, design, finite element analysis and results of the assembled
subsystems: slit-mask, and the acquisition and guiding zone mechanisms of the ESOPO spectrograph. This spectrograph
is a project of the Institute of Astronomy, National University of Mexico.
In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1m
Telescope at the Observatorio Astronómico Nacional at San Pedro Mártir. We discuss the Scientific Goals and the High
Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an
introduction to its conceptual dual-arm design. The optical design is based on a non-classical configuration. The gratings
are illuminated in a conical mode working in a quasi Littrow configuration which has the advantage of optimizing the
efficiency and the pupil area on the grating. We show here the results of an experimental evaluation of the concept. The
optical design, mechanical structure, slit-mask and acquisition system, control systems, and a study of thermal
compensators, are discussed briefly, references to more extended contributions in these proceedings are made. The
management schematics of the project are briefly discussed.
KEYWORDS: Digital signal processing, Sensors, Electronics, Cameras, Optical filters, Imaging spectroscopy, Infrared cameras, Signal detection, Telescopes, Signal processing
CATAVIÑA is a near-infrared camera system to be operated in conjunction with the existing multi-purpose nearinfrared
optical bench "CAMALEON" in OAN-SPM. Observing modes include direct imaging, spectroscopy, Fabry-
Perot interferometry and polarimetry. This contribution focuses on the optomechanics and detector controller
description of CATAVIÑA, which is planned to start operating later in 2006. The camera consists of an 8 inch LN2
dewar containing a 10 filter carousel, a radiation baffle and the detector circuit board mount. The system is based on a
Rockwell 1024x1024 HgCdTe (HAWAII-I) FPA, operating in the 1 to 2.5 micron window. The detector
controller/readout system was designed and developed at UNAM Instituto de Astronomia. It is based on five Texas
Instruments DSK digital signal processor (DSP) modules. One module generates the detector and ADC-system control,
while the remaining four are in charge of the acquisition of each of the detector's quadrants. Each DSP has a built-in
expanded memory module in order to store more than one image. The detector read-out and signal driver subsystems
are mounted onto the dewar in a "back-pack" fashion, each containing four independent pre-amplifiers, converters and
signal drivers, that communicate through fiber optics with their respective DSPs. This system has the possibility of
programming the offset input voltage and converter gain. The controller software architecture is based on a client/server
model. The client sends commands through the TCP/IP protocol and acquires the image. The server consists of a
microcomputer with an embedded Linux operating system, which runs the main program that receives the user
commands and interacts with the timing and acquisition DSPs. The observer's interface allows for several readout and
image processing modes.
A novel hydrodynamic radial polishing tool (HyDRa) is presented. It performs corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrodynamic suspension system that avoids contact of the tool with the working surface. With this tool it is possible to polish aspheres and free-form optics on diverse materials and sizes. The functioning principle is based on the generation of a grazing, high-velocity, low-pressure, rotational, variable density, abrasive flux with radial geometry. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The polishing process is repeatable and achieves high degrees of precision and accuracy on optical and semiconductor surfaces. This tool is particularly useful for polishing thin substrates such as membranes and semiconductors since it can be biased for a non-interactive action on the work piece. An additional advantage of this new tool is the possibility to perform in-process interferometric measurements. Polishing results on assorted materials using HyDRa are presented.
New results using hydrodynamic radial polishing techniques on assorted materials, using HyDRa are presented. This tool performs corrective lapping and fine polishing by means of a low-cost, foamy abrasive flux. The functioning principle is based on the generation of a grazing, high-velocity, low-pressure, rotational, variable density, abrasive flux with radial geometry. It is currently possible to polish aspheres and free-form optics on diverse materials and sizes. This tool is particularly useful for polishing thin substrates such as membranes and semiconductors since it can be biased for a non-interactive action on the work piece. This process also has the advantage of achieving high removal rates. In order to achieve high degrees of accuracy and repeatability in the HyDRa finishing process, fully automated bias and slurry supply units must be incorporated to the polishing system. The air and slurry supply systems are described, as well as operational tool parameters for optimal polishing performance.
A novel hydrodynamic radial polishing tool (HyDRa) is presented. It performs corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. With this tool it is currently possible to polish aspheres and free-form optics of up to 2.5 meters in diameter. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The functioning principle is based on the generation of a high-velocity, high-pressure abrasive emulsion flux with radial geometry. The polishing process is repeatable and achieves high degrees of precision and accuracy on optical and semiconductor surfaces. An additional advantage of this new tool is the possibility to perform in-process interferometric measurements. Recent results of polished aspheres are discussed.
We present a new algorithm that applies the correlation functions to phase shifting interferometry to recover the phase of a test surface. In this work we make numerical simulations to test the algorithm and the results are verified with real interferograms. The correlation algorithm recovers the phase value with 5% accuracy.
In order to overcome classic polishing techniques, a novel hydrodynamic radial polishing tool (HyDRa) is presented; it is useful for the corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. This tool enables the work on flat or curved surfaces of currently up to two and a half meters in diameter. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The functioning principle is based on the generation of a high-velocity, high-pressure, abrasive emulsion flux with radial geometry. The polishing process is repeatable by means of the control of the tool operational parameters, achieving high degrees of precision and accuracy on optical and semiconductor surfaces, with removal rates of up to 9 mm3/hour and promising excellent surface polishing qualities. An additional advantage of this new tool is the possibility to perform interferometric measurements during the polishing process without the need of dismounting the working surface. A series of advantages of this method, numerical simulations and experimental results are described.
HyDRa is a hydrodynamic radial polishing tool ideal for the corrective lapping and fine polishing of diverse materials by means of an accelerated abrasive flux. The roughness of an optical surface is analysed for a continuous manufacturing process, beginning with the basic generation steps up to a finished optical surface. These results were obtained using a Linnik interferometer.
The support system of the primary mirror of 2.1m telescope at SPM allows correction of some optical aberrations. A low cost Active Optics System (AOS) can be developed based on this property of the support system. Within the preliminary development of this system, computer simulations were being performed. The general propose of simulations was to find the optimal scheme for the wavefront control of the primary mirror. This paper presents results for the wavefront sensor of the AOS proposed for the 2.1m telescope at San Pedro Martir.
The wavefront sensor is an important part of active control for an Active Optics System (AOS). The wavefront sensibility of a beam compressor is experimentally tested on the 2.1m telescope at SPM. This is a simple wavefront sensor based on the wave propagation equation. A qualitative analysis of the experimental data is presented. It is concluded that the beam compressor has enough sensibility to be used as a wavefront sensor for the AOS.
Two main trends presently prevail in ELT design: arrays of hundreds of small (1 - 2 m) hexagonal mirrors and the use of several large (~8m) monolithic mirrors. We present a conceptual study of an off axis 8 m telescope with different mirror options, which can be useful as an experiment towards the design of large multi-mirror telescopes, in terms of different mirror materials, ideas for the optics and new solutions for the telescope mechanical assembly.
We present the dual IR camera CID for the 2.12 m telescope of the
Observatorio Astronomico Nacional de Mexico, IA-UNAM. The system
consists of two separate cameras/spectrographs that operate in
different regions of the IR spectrum. In the near IR, CID comprises a direct imaging camera with wide band filters, a CVF, and a low resolution spectrograph employing an InSb 256 x 256 detector. In the mid IR, CID uses a BIB 128 x 128 detector for direct imaging in 10 and 20 microns. Optics and mechanics of CID were developed at IR-Labs
(Tucson). The electronics was developed by R. Leach (S. Diego). General design, construction of auxiliary optics (oscillating
secondary mirror), necessary modifications and optimization of
the electronics, and acquisition software were carried out at OAN/
UNAM. The compact design of the instruments allow them to share
a single dewar and the cryogenics system.
We propose a method for piston errors detection in a segmented surface by means of the classical ronchi test. This consists in comparing the ronchigram fringes frequency of a reference and piston segment. The comparison is developed for the correlation method of the intensity vs pixels curves of the reference and piston segment. The presence of the piston term in a ronchigram is assured experimentally for the shack interferometer, it is by observing the coincidence rings centered type fizeau in each segment. The proposed method is applied to a segmented spherical surface with a two segment mirrors, and resolutions of piston ⩾63 ηm are experimentally obtained.
In the polishing process, the wear tends to be greater when the tool extends beyond the edge of the workpiece. A linear pressure distribution (between the tool and the workpiece) has been used to explain this effect, however, this model also can predict negative pressures. This could mean that material is deposited instead of being removed. We present a new pressure distribution proposal, which presents like a skin effect. This means that the pressure is significantly higher at the border points than at internal points of the glass. With this model the material removal at the border points is increased considerably since, according to Preston, the wear is proportional to the pressure. This pressure distribution model is applied to calculate the wear produced by a square tool on a glass border moving along straight lines.
We report experimental results and analysis about a new hydrodynamic radial tool (HyDra, patent pending), which expels a suspension of water and polishing particles radially on glass. With this method it is possible to locally shape optical surfaces. The depth of material removed by HyDra grows linearly with the time. The removal rate is independent of the velocity between the tool and the glass element. The HyDra has been used to fabricate successfully an optical flat and Schmidt surface.
We propose one method for the phase alignment of segmented mirrors with piston errors. For this, we use the classical Ronchi test to observe fringes around of curvature center, after we take some lines on the Ronchi image for each segment mirror and obtain its intensity vs. pixels, to do the correlation and approximate the amount of pixels or piston displacement for the phase misalignment. Additionally, we get parabolic fit to find resolutions of sub-pixels. At the same time, we use the Shack Interferometer to observe behavior rings centered for this two segment mirrors to compare with the fringes produced with Ronchi test and to achieve resolutions of piston >= 24 (eta) m.
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).
In this paper, the characteristics of a mount for secondary mirror of an astronomical telescope are presented. The mount has five freedom degrees. The control allows to focus with errors of +/- 1 micron and to align with inclinations and displacements with error of +/- 3.48 arcsec and +/- 8.3 micron respectively. The optical tests are presented before and after placing this mount, as well as control electronics and mechanical details.
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.
We are developing an instrument to study the morphology and kinematics of the molecular gas and its interrelationship with the ionized gas in star forming regions, planetary nebulae and supernova remnants in our Galaxy and other galaxies, as well as the kinematics of the IR emitting gas in starburst and interacting galaxies. This instrument consists of a water-free fused silica scanning Fabry-Perot interferometer optimized in the spectral range from 1.5 to 2.4 micrometers with high spectral resolution. It will be installed in the collimated beam of a nearly 2:1 focal reducer, designed for the Cassegrain focus of the 2.1 m telescope of the San Pedro Martir National Astronomical Observatory. Mexico, in its f/7.5 configuration, yielding a field of view of 11.6 arc-min. It will provide direct images as well as interferograms to be focused on a 1024 X 1024 HAWAII array, covering a spectral range from 0.9 to 2.5 micrometers .
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