Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of
lightweight materials like glass or plastic in order to keep the total mass within acceptable limits. Optics based on thin
slumped glass foils are currently in use in the NuSTAR telescope and are being developed at various institutes like
INAF/OAB, aiming at improving the angular resolution to a few arcsec HEW. Another possibility would be the use of
thin plastic foils, being developed at SAO and the Palermo University. Even if relevant progresses in the achieved
angular resolution were recently made, a viable possibility to further improve the mirror figure would be the application
of piezoelectric actuators onto the non-optical side of the mirrors. In fact, thin mirrors are prone to deform, so they
require a careful integration to avoid deformations and even correct forming errors. This however offers the possibility to
actively correct the residual deformation. Even if other groups are already at work on this idea, we are pursuing the
concept of active integration of thin glass or plastic foils with piezoelectric patches, fed by voltages driven by the
feedback provided by X-rays, in intra-focal setup at the XACT facility at INAF/OAPA. In this work, we show the
preliminary simulations and the first steps taken in this project.
This work is developed in the framework of AXYOM project, which proposes to study the application of a system of piezoelectric actuators to grazing-incidence X-ray telescope optic prototypes: thin glass or plastic foils, in order to increase their angular resolution. An integrated optomechanical model has been set up to evaluate the performances of X-ray optics under deformation induced by Piezo Actuators. Parametric evaluation has been done looking at different number and position of actuators to optimize the outcome. Different evaluations have also been done over the actuator types, considering Flexible Piezoceramic, Multi Fiber Composites piezo actuators, and PVDF.
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 opto-mechanical conceptual design for the Front-End unit and the calibration unit of the ESPRESSO Spectrograph is
described in this paper. The front end system exploits a modular concept. Each FEU receive the beam directly from the
relative Telescope Coudé Train and the calibration light from the calibration unit. On the other side the FEU feeds the
fibers that carry the light to the spectrograph, corresponding in number and size to the scientific observing modes
conceived for Espresso. The selection is made through a Toggling Unit. Purpose of the Front/End is to provide the
needed connection between the input signal, i.e. Object light, Sky light, Calibration light, and the given output fiber in
any of the foreseen observing modes.
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