Not only could the segmented mirrors synthetic aperture optical system improve the sensitivity and
resolution of telescope system, but also meet the demands of NGST (next generation space
telescope).In order to ensure segmented mirrors keep the same optical performance of mono-mirror,
that is, the phase error less thanλ/20, each segmented mirror should have its own nano-grade high
precision correcting device. In this paper, the synthetic aperture is composed of three segmented
mirrors, one fixed and the other two adjustable, each of which achieved 6-DOF adjustment by three
micro-displacement actuators and the characters of the actuators are researched. For the purpose of
nano-grade positioning, PZT is used as the micro-displacement actuator. In our research, the jointing
process is rough-tuned by mechanical structure before fine-tuned by PZT, so there's no need for the
PZT to work in the full range. In order to provide basic support for nano-grade phase error correction, it
is very necessary to calibrate the relationship between the elongation distribution of each PZT and the
regulating voltage for each actuator, in its own scope of work with small step, because of the hysteresis
of PZT.
A new alloyed crystal, Yb:LYSO, has been grown by the Czochralski method in our institute for the first time, and its
effective diode-pumped cw tunable laser action was demonstrated. The alloyed crystal retains excellent laser properties
of LSO with reduced growth cost, as well as the favorable growth properties of YSO. With a 5-at.% Yb:LYSO sample,
we achieved 2.84 W output power at 1085 nm and a slope efficiency of 63.5%. And its laser wavelength could be tuned
over a range broader than 80nm, from 1030nm to 1111 nm. This is the broadest tunable range achieved for Yb:LYSO
laser, as far as we know.
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