Antonio Marchamalo Sánchez

Atmosphere and telescope simulator for new adaptive optics methods development

The IACAT (IAC Atmosphere and Telescope) Simulator is an Optical Ground Support Equipment which simulates atmospheric turbulence and reproduces the performance of three very different telescopes: GTC and WHT, located at the Observatorio Del Roque de los Muchachos in La Palma (Canary Islands), and OGS which is located at the Observatorio Del Teide in Tenerife (Canary Islands). Its mission is to provide Scientists with the same measurement conditions as the real telescope but in a friendly laboratory environment, to assist in the development of new adaptive optics methods based on FPGAs. The most important telescope characteristics are simulated, such as f number, pupil size and position, magnification, central obscuration, etc. Up to 13 stellar objects can be created, individually or as binary stars with specific angular separations down to miliarcseconds. For the atmosphere simulation, it allows the creation of three different turbulence layers concurrently with different altitude and wind speed ranges.

The MIRI cold telescope simulator

The MIRI Telescope Simulator (MTS) is part of the Optical Ground Support System (OGSE) for the verification and calibration phase of the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). The MTS will simulate the optical characteristics of the JWST output beam in an environment similar to the flight conditions. The different functionalities of the MTS are briefly described and its current design, including the illumination and imaging subsystems, is presented.

Analysis and evaluation of the Full Disk Telescope refocusing mechanism for the Solar Orbiter mission

Abstract. The Full Disk Telescope is part of the Polarimetric Helioseismic Instrument on board the future Solar Orbiter ESA/NASA mission. It will provide full-disk measurements of the photospheric magnetic field vector and line-of-sight velocity, as well as the continuum intensity in the visible wavelength range. Along this mission, it is expected that thermal drifts will induce image focus displacements. Consequently, providing an autofocus system is mandatory to prevent image degradation. The refocusing system is based on an autonomous image contrast analysis and it allows for a lens displacement in order to locate the best focus position. The figure of merit chosen for the image quality evaluation is presented. The influences of attitude instability and mechanical uncertainties are considered in a refocusing process simulation. In addition, an engineering model of the mechanism is tested at flight operating conditions. To check its performance, an optical interrogation system is set up. Determination of accuracy and repeatability of the mechanism positioning is experimentally evaluated and discussed according to the ISO standard. The results show that the proposed refocusing system is sufficiently robust against the expected image shifts and mechanical instabilities.

Cryogenic filter wheel design for an infrared instrument

In the last two decades, Spain has built up a strong IR community which has successfully contributed to space instruments, reaching Co-PI level in the SPICA mission (Space Infrared Telescope for Cosmology and Astrophysics). Under the SPICA mission, INTA, focused on the SAFARI instrument requirements but highly adaptable to other missions has designed a cryogenic low dissipation filter wheel with six positions, taking as starting point the past experience of the team with the OSIRIS instrument (ROSETTA mission) filter wheels and adapting the design to work at cryogenic temperatures. One of the main goals of the mechanism is to use as much as possible commercial components and test them at cryogenic temperature. This paper is focused on the design of the filter wheel, including the material selection for each of the main components of the mechanism, the design of elastic mount for the filter assembly, a positioner device designed to provide positional accuracy and repeatability to the filter, allowing the locking of the position without dissipation. In order to know the position of the wheel on every moment a position sensor based on a Hall sensor was developed. A series of cryogenic tests have been performed in order to validate the material configuration selected, the ball bearing lubrication and the selection of the motor. A stepper motor characterization campaign was performed including heat dissipation measurements. The result is a six position filter wheel highly adaptable to different configurations and motors using commercial components. The mechanism was successfully tested at INTA facilities at 20K at breadboard level.