WEAVE is a new wide-field spectroscopy facility proposed for the prime focus of the 4.2m William Herschel Telescope (WHT), placed in La Palma, Canary Islands, Spain.
To allow for the compensation of the effects of temperature-induced and gravity-induced image degradation, the WEAVE prime focus assembly will be translated along the telescope optical axis. The assembly comprises the prime focus corrector with integrated ADC, a central mount for the corrector, an instrument rotator and a twin-focal-plane fibre positioner. Translation is accomplished through the use of a set of purpose-built actuators; collectively referred to as the Focus Translation System (FTS), formed by four independently-controlled Focus Translation Units (FTUs), eight vanes connecting the FTUs to a central can, and a central can hosting WEAVE Instrument. Each FTU is capable of providing a maximum stroke of ±4mm with sufficient, combined force to move the five-tonne assembly with a positional accuracy of ±20μm at a resolution of 5μm. The coordinated movement of the four FTUs allows ±3mm WEAVE focus adjustment in the optical axis and ±0.015° tilt correction in one axis. The control of the FTS is accomplished through a PLC-based subsystem that receives positional demands from the higher-level Instrument Control System.
SENER has been responsible for designing, manufacturing and testing the FTS and the equipment required to manipulate and store the FTS together with the instrument.
This manuscript describes the final design of the FTS along with the analyses and simulations that were performed, discusses the manufacturing procedures and the results of early verification prior to integration with the telescope. The plans for mounting the whole system on the telescope are also discussed.
JPCam is designed to perform the Javalambre-PAU Astrophysical Survey (J-PAS), a photometric survey of the northern
sky with the new JST telescope being constructed in the Observatorio Astrofísico of Javalambre in Spain by CEFCA
(Centro de Estudios de Física del Cosmos de Aragón).
SENER has been responsible for the design, manufacturing, verification and delivery of the JPCam Actuator System
that will be installed between the Telescope and the cryogenic Camera Subsystem. The main function is to control the
instrument position to guarantee the image quality required during observations in all field of view and compensate
deformations produced by gravity and temperature changes.
The paper summarizes the main aspects of the hexapod design and earliest information related of integration and
performances tests results.
The Configurable Slit Unit (CSU) is a key module of EMIR (wide field NIR multi-object spectrograph) which will be one of the key next generation instruments of the Gran Telescopio de Canarias (GTC). The CSU enables a multi-slit configuration, a long slit, or an imaging aperture in the 6’x6’ (340mm x 340mm) field of view. This is realized by 110 sliding bars which can be configured at cryogenic working temperature to create 55 slits with a position accuracy of 6 micron. The CSU incorporates a number of enabling technologies which have been developed, validated and matured as a part of the total development of the CSU. Dedicated actuator drive and position measurement technologies have been successfully developed. Also a selective surface treatment technology, to give detailed features on the same part opposite emissivity performances, has been developed. All these technologies are currently implemented in the realization of the unit. Manufacturing of components for the unit has challenged state of the art production equipment and skills to the limit due to the size, number, accuracy and complexity of the parts and features. Integration and verification of the CSU is advancing. Both mechanics as electronics have been tested at sub-module level. Ahead is the challenge of actual integration of the electronics and software in order to get the mechanical hardware to operate within specification. Control strategies are developed and tuned to guarantee robust operation of the unit in cryogenic working environment. As a final integration step all individual axes are calibrated with an external interferometer measurement system.
The M5 Field stabilization Unit (M5FU) for European Extremely Large Telescope (E-ELT) is a fast correcting optical
system that shall provide tip-tilt corrections for the telescope dynamic pointing errors and the effect of atmospheric tiptilt
and wind disturbances.
A M5FU scale 1 demonstrator (M5FU1D) is being built to assess the feasibility of the key elements (actuators, sensors,
mirror, mirror interfaces) and the real-time control algorithm. The strict constraints (e.g. tip-tilt control frequency range
100Hz, 3m ellipse mirror size, mirror first Eigen frequency 300Hz, maximum tip/tilt range ± 30 arcsec, maximum tiptilt
error < 40 marcsec) have been a big challenge for developing the M5FU Conceptual Design and its scale 1
The paper summarises the proposed design for the final unit and demonstrator and the measured performances
compared to the applicable specifications.
The European Solar Telescope (EST) is a European collaborative project to build a 4m class solar telescope in the
Canary Islands, which is now in its design study phase. The telescope will provide diffraction limited performance for
several instruments observing simultaneously at the Coudé focus at different wavelengths. A multi-conjugated adaptive
optics system composed of a tip-tilt mirror and several deformable mirrors will be integrated in the telescope optical
The secondary mirror system is composed of the mirror itself (Ø800mm), the alignment drives and the cooling system
needed to remove the solar heat load from the mirror. During the design study the feasibility to provide fast tip-tilt
capabilities at the secondary mirror to work as the adaptive optics tip-tilt mirror is also being evaluated.
This paper summarizes the main aspects of the design and qualification test results of the ALMA Amplitude Calibration
Device Robotic Arm (ACD). The design aspects of the ACD, including a detailed description of the components selected to achieve the expected performances are presented in the first part of the paper. Also the system performances results measured in the first prototype units are summarized at the last part of the paper.
A 42 meters telescope does require adaptive optics to provide few milli arcseconds resolution images. In the current
design of the E-ELT, M4 provides adaptive correction while M5 is the field stabilization mirror. Both mirrors have an
essential role in the E-ELT telescope strategy since they do not only correct for atmospheric turbulence but have also to
cancel part of telescope wind shaking and static aberrations. Both mirrors specifications have been defined to avoid
requesting over constrained requirements in term of stroke, speed and guide stars magnitude. Technical specifications
and technological issues are discussed in this article. Critical aspects and roadmap to assess the feasibility of such
mirrors are outlined.
This paper summarizes the main aspects of the design and qualification test results of the secondary mirror mechanism
for the VISTA Telescope. A design overview is presented, with detailed description of the main aspects of the system
including the electromechanical part and the control system. Also a description of the test facilities and test
methodologies is provided prior to the presentation and discussion of the performance test results.
This paper summarizes the main aspects of the design and qualification test results of the secondary mirror mechanism for the 10.4-m Gran Telescopio Canarias (GTC). The design of the M2DS consists of a two stage mechanism, a hexapod for alignment using six linear actuators and a compensated tilt/chop stage with three voice coils taking its base on the hexapod mobile plate. The system has been tested after servos adjustment and calibration and the latest results are presented, which illustrate the quality and accuracy of this mechanism in both alignment and chop performances. Finally, the results and experiences are summarized in order to provide useful information for new developments of such systems.