August 27 16:00 - 18:30, ATF LC meeting room, KEK
Participants : Tauchi, Terunuma, Kuroda, Okugi, Araki, Honda, Yamanaka, Kamiya(WebEx)
*** Report on Fringe Phase Monitor ***
by using this monitor we estimate the phase jitter at the IP
goal of phase stability is less than 200 mrad (RMS in 1 minute)
measurement result:
* unstatilized
400 mrad
* 1 channel stabilized
170 mrad (stabilized channel)
310 mrad (unstabilized channel)
* average 2 channel stabilized
210 mrad (both channel)
If we can assume the fringe phase at the IP is correlate with
these phase monitors, the phase stability at the IP is also
200 mrad level.
** question, comment and suggestion **
Q: Do room temperature, cooling water temperature, floor vibration
affect the phase stability?
A: It is possible, though in measurement performed at the univerty
which uses CW laser instead of the pulsed laser, the better phase
stability was aquired (30 mrad : stabilized channel, 70 mrad
unstabilized channel).
Therefore the worse phase stability may be due to the angular
jitter of the pulsed laser.
Suggestion: It takes several hours to stabilize the pulsed laser,
you need to wait before start the measurement.
Q: The phase stability difference between the stabilized channel
and unstabilized channel is too different. Aren't there any defects
in measurement methods?
A: If I swap stabilizing channel, the phase stability is also swapped.
It seems to be no problem in measurement methods. This difference
may be due to the weak correlation of two channls.
Suggestion: Why don't you see the correlation between the phase,
and position monitor? If the phase jitter is came from the angluar
jitter, you can see some correlation.
