1. Pyramid sensors for AO and co-phasing
Two key projects in Arcetri AO groups for 8m class telescopes and ELT wavefront sensing:
-WFS for LBT AO system
-Segment co-phasing for EELT

2. Pyramid WFS in Adaptive Optics
A Strehl Ratio plot (peak value of the corrected PSF normalized to peak value for perfect correction) as a function of guide star magnitude in R band for Pyramid Sensor (PS) and Shack-Hartmann sensor (SH).
PS is less sensitive to uncorrected
atmospheric perturbations. Energy
left In the PSF halo is 1/3 for PS.
Enabling higher PSF contrast.
PS achieve same performance
With a star about 2 mag fainter.
AO system sky coverage is
doubled. SH PS
Strehl Ratio in seeing
limited case (8m tel.)

3. AO system for LBT -An astronomical AO system with two key components:
1) DM: a deformable secondary with 672 actuators.
2) Sensor: a pyramid WFS with up to 30x30 subapertures.
-AO system coupled to mm DL imager & spectrograph LUCIFER
the main LBT instrument for diffraction limited observations
Project main dates:
-AO #1 comm. date: Dec08
-AO #2 comm. date: Sep09
FLAO on LBT telescope
The secondary unit
The pyramid WFS unit

4. A closer view to WFS unit
Wavefront sensing W unit
Acquisition & guiding AG unit
The WFS board during integration
The glass pyramid
for LBT WFS

5. Closed loop lab test of the AO system
The lab set-up for AO system test
Closed loop lab test of the AO system
45-actuator prototype
The 45 actuators prototype
of deformable secondary
WFS unit

6. Segment co-phasing for the ELT
Arcetri AO group demonstrated that the Pyramid sensor can detect simultaneously
segment differential piston as well as tip and tilt of the segments.
-A single WFS for segmented mirror alignment
-A single WFS for co-phasing and AO
Closed loop alignment
of the segmented DM
of NAOMI AO WHT
[Opt.Lett.,Esposito,2005]
Piston signals, (X,Y)
Tip tilt rms
Piston rms
Tilt signals (X,Y)

7. The active Phasing Experiment (APE)
Active Phasing Experiment (APE) is the WP4600
of the ELT Design Study. Experiment is aimed to
realize , test and compare three co-phasing
Sensor in lab at ESO and at the VLT.
Initial rms > λ/2
Co-phasing loop:
Start 110nm rms
Stop 12nm rms
Final rms 23nm

8. New projects: LGS GLAO system for LBT MCAO for EELT phase A study
A project to provide LBT with a Laser Guide Star Ground Layer AO system is started as phase A study in May07. The program has an upgrade path aimed to extend GLAO system to LGS diffraction limited AO for imaging on small FoV.
-GLAO system will be coupled with the multi-object spectroscopic unit of LUCIFER having a 4x2 arcmin FoV.
MCAO for EELT phase A study
ONERA
Oss. Ast.
Padova
A 2 years phase A study to analize
the design of a Multi-Conjugate AO
system for the EELT leaded by
Osservatorio di Bologna (OAB).