We introduce the opto-mechanical architecture of a high precision, full Stokes vector, dual-channel polarimeter for the
European Extremely Large Telescope’s High Resolution spectrograph (E-ELT HIRES). It is foreseen to feed two
spectrograph modules simultaneously through the standard Front End subunit located on the Nasmyth platform via two
fiber bundles; one optimized for the optical (BVRI), the other optimized for the infrared (zYJH) bands. The polarimeter
is located below M4 in the f/4.4 intermediate focus, representing the only rotationally symmetric focus available, and is
retractable. We illustrate the strategy of repositioning and aligning the instrument, provided that it has to withstand wind
and earthquake loads and that the PSF is varying in width and position due to the active compensation by the co-phasing
corrections. Preliminary results of its expected polarimetric sensitivity and accuracy are also analyzed for several
configurations of M1 segments and suggest a stunning performance in the intermediate focus with cross talks of the
order of 10-7 but 10-2 if it were located in the Nasmyth focus.
We present the design, architecture and results of the End-to-End simulator model of the high resolution spectrograph
HIRES for the European Extremely Large Telescope (E-ELT). This system can be used as a tool to characterize the
spectrograph both by engineers and scientists. The model allows to simulate the behavior of photons starting from the
scientific object (modeled bearing in mind the main science drivers) to the detector, considering also calibration light
sources, and allowing to perform evaluation of the different parameters of the spectrograph design. In this paper, we will
detail the architecture of the simulator and the computational model which are strongly characterized by modularity and
flexibility that will be crucial in the next generation astronomical observation projects like E-ELT due to of the high
complexity and long-time design and development. Finally, we present synthetic images obtained with the current
version of the End-to-End simulator based on the E-ELT HIRES requirements (especially high radial velocity accuracy).
Once ingested in the Data reduction Software (DRS), they will allow to verify that the instrument design can achieve the
radial velocity accuracy needed by the HIRES science cases.
In this paper we will review the ESPRESSO guiding algorithm for the Front End subsystem. ESPRESSO, the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESO’s Very Large Telescope (VLT). The Front End Unit (FEU) is the ESPRESSO subsystem which collects the light coming from the Coudè Trains of all the Four Telescope Units (UTs), provides Field and Pupil stabilization better than 0.05’’ via piezoelectric tip tilt devices and inject the beams into the Spectrograph fibers. The field and pupil stabilization is obtained through a re-imaging system that collects the halo of the light out of the Injection Fiber and the image of the telescope pupil. In particular, we will focus on the software design of the system starting from class diagram to actual implementation. A review of the theoretical mathematical background required to understand the final design is also reported. We will show the performance of the algorithm on the actual Front End by adoption of telescope simulator exploring various scientific requirements.
In this paper we present an efficient tool developed to perform opto-mechanical tolerance and sensitivity analysis both for the preliminary and final design phases of a spectrograph. With this tool it will be possible to evaluate the effect of mechanical perturbation of each single spectrograph optical element in terms of image stability, i.e. the motion of the echellogram on the spectrograph focal plane, and of image quality, i.e. the spot size of the different echellogram wavelengths. We present the MATLAB-Zemax script architecture of the tool. In addition we present the detailed results concerning its application to the sensitivity analysis of the ESPRESSO spectrograph (the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations which will be soon installed on ESO’s Very Large Telescope) in the framework of the incoming assembly, alignment and integration phases.
slicer, is necessary to differently fold each field to correctly illuminate the echelle and this is made by cylindrical prisms glued onto a silica window. We present the integrated robotic system conceived to reach the required tolerances in term of alignment and integration. It consists in a tip/tilt stage to select the wedge angle, a rotational stage to select the right clock angle, coupled to an x-y stage to position the elements on the window and a z axis to perform the gluing.
In this paper we present an innovative philosophy to develop the End-to-End model for astronomical observation projects, i.e. the architecture which allows physical modeling of the whole system from the light source to the reduced data. This alternative philosophy foresees the development of the physical model of the different modules, which compose the entire End-to-End system, directly during the project design phase. This approach is strongly characterized by modularity and flexibility; these aspects will be of relevant importance in the next generation astronomical observation projects like E-ELT (European Extremely Large Telescope) because of the high complexity and long-time design and development. With this approach it will be possible to keep the whole system and its different modules efficiently under control during every project phase and to exploit a reliable tool at a system engineering level to evaluate the effects on the final performance both of the main parameters and of different instrument architectures and technologies. This philosophy will be important to allow scientific community to perform in advance simulations and tests on the scientific drivers. This will translate in a continuous feedback to the (system) design process with a resulting improvement in the effectively achievable scientific goals and consistent tool for efficiently planning observation proposals and programs. We present the application case for this End-to-End modeling technique, which is the high resolution spectrograph at the E-ELT (E-ELT HIRES). In particular we present the definition of the system modular architecture, describing the interface parameters of the modules.
We present the details of a paraxial parametric model of a high resolution spectrograph which can be used as a tool, characterized by good approximation and reliability, at a system engineering level. This model can be exploited to perform a preliminary evaluation of the different parameters as long as different possible architectures of high resolution spectrograph like the one under design for the E-ELT (for the moment called E-ELT HIRES in order to avoid wrong association with the HIRES spectrograph at Keck telescope). The detailed equations flow concerning the first order effects of all the spectrograph components is described; in addition a comparison with the data of a complete physical ESPRESSO spectrograph model is presented as a model proof.
This paper presents the Espresso Anamorphic pupil Slicer (APSU) implementation. For ESPRESSO that will be installed
on ESO’s Very Large Telescope (VLT). In this work we will present the design and trade off for the pupil slicing system
introduced in order to increase the resolving power, effectively decreasing slit width. It’s based onto simplified optical
component that introduce large anamorphism while keeping low aberrations by means of cylindrical optics. We describe
here the trade off between slicing through two adjacent squared doublets and two achromatic prisms. Preliminary
integration and procurement is also discussed here.
The multiprism device is a crucial component of the Espresso Anamorphic pupil Slicer (APSU). At the end of the slicer,
is necessary to differently fold each field to correctly illuminate the echelle. The solution is made by gluing cylindrical
prisms with proper bending low angle onto a support double plate silica window. We present here the integrated robotic
system conceived to reach the required tolerances in term of alignment and Integration. It consist in a tip tilt stage to
select the folding angle, coupled to an x-y stage to position the elements and a z axis to perform the gluing.
Keywords: Extra-solar Planet Atmospheres, High Resolution Spectroscopy, Espresso, front End