Adaptive optics and related technologies
The INAF community active in the area of ground based telescope technology has developed considerable know-how in the field of adaptive optics. This was developed, above all, with the development of the TNG - Telescopio Nazonale Galileo (to which almost all of the Italian astronomical observatories contributed), that is equipped with an active optics system. The participation in the LBT then gave a tremendous impulse to this sector. This level of excellence is widely acknowledged at the international level.
At the moment, the development of adaptive optics technologies is having a significant impact on the design of the Extremely Large Telescope (diameter much greater than8 metres). Although the process of development of telescopes of this class (E-ELT for example) has just begun, the development of technologies related to the construction of precursor instruments on 8 metre class telescopes represents a specific know-how thatINAF must maintain, so as to provide a technology rich contribution to the building of theE-ELT. Amongst other things, Italy, through the ADS and Microgate companies, already coordinates a consortium funded by ESO for a feasibility study of the plane adaptive mirrorM4 for the E-ELT, of which INAF-OABr is sub-contractor. A telescope of these dimensions requires adaptive optics to obtain images with a resolution of a few milliarc seconds.
For technologies related to adaptive optics, of particular importance is the development of wavefront sensors, apparatus for the generation of artificial reference systems ("laser stars"), as well as the development of corrective mirrors (generally called "adaptive secondaries"). In all these areas INAF has the knowledge and a level of technological development that embrace almost all the possible implementation scenarios.
In particular, of the technological aspects related to adaptive optics currently under development within INAF, that have to be sustained and supported, the following are emphasised:
- The development of technologies for thin, deformable mirrors, with electromagnetic actuators, including the development of the associated optical components and metrology, innovative moulding technology (hot slumping) for thin shells, capacitive sensors and actuators, electronics and control systems.
- The development of new kinds of wavefront sensors, able to observe both natural and artificial reference stars (also in an unconventional way), deriving information not traditionally produced, such as the three dimensional structure of turbulence or phase shift between the various sectors of the main mirror.
- The optimisation of the observing strategy to maximise the scientific return of instruments served by adaptive optics, encouraging meetings, working groups and workshops both at the national and international level.
Research based on the use of Orbital Angular Momentum of electromagnetic beams to produce optics with super-resolution and new generation coronagraphs both for space and the ground (together with adaptive optics) should also be mentioned.