![[M1 lifted from the cell]](46.gif) |
The 3.5-m primary mirror is lifted from its cell after completion of the
optical tests at Zeiss (Germany).
Its thickness is only 24 cm. Note along the border the pads for the
lateral support system. From the top surface of the cell emerge the heads
of the 78 actuators.
|
|
One of the interferograms taken at Zeiss with the Laser Unequal Path
Interferometer at a lambda=632.8 nm.
| ![[Test results]](48.gif) |
![[Interferogram]](ottica1.gif) |
The mirror on its cell after closure of the active optics loop,
and adjustment of the whole mirror weight.
Counterclockwise from upper right: i) the forces on the
actuators are set to the optimum; ii) the departure of the mirror
surface
from the ideal one is shown via a wavefront phase map determination,
obtaining approx 39 nm RMS;
iii) the PSF shape is round and the first diffraction ring is clearly
visible; iv) the DEE behaves as in a diffraction limited mirror
(EE(80%) <= 0.''11 for 406x406 sampling points). |
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The diffraction Encircled Energy and the related PSFs displayed for
three relevant cases: white, the diffraction limited case, taking
into
account the central obstruction; red before, and green after
the
active optics correction. As can be easily seen, active optics correction
leads to a performance very close to the diffraction limited one.
| ![[Test result]](ottica2.gif) |
