aLIGO LHO Logbook

H1 PSL

richard.savage@LIGO.ORG - posted 05:39, Wednesday 07 December 2011 - last comment - 17:29, Wednesday 07 December 2011(1848)

Shutdown and dismantling of H1 PSL

PeterK, JanP, MichaelR, RickS

Yesterday, we made some final parameter measurements for the H1 PSL, inspected the pump fiber surfaces, then shut down and began dismantling the H1 PSL.

As of last evening, the pump fibers have been pulled back to the H1 Laser Diode Room, the electronics racks have been partially gutted, and we are beginning to remove components from the table.

Right now we are focusing on the components that we will reuse for the H1 aLIGO PSL.

We expect this process to continue into next week, partly because we want to spend as much time as possible working with JanP on the H2 PSL this week, which is his last before heading back to Germany on Friday.

We will post the measurement and inspection results shortly.

Comments related to this report

richard.savage@LIGO.ORG - 17:29, Wednesday 07 December 2011 (1855)

Link

Pre-shutdown measurements

1) NPRO
NPRO power: 1.957W (measured just upstream of EOM)
NPRO current: 2.297A
NPRO temperatures (taken from EPICS): D2 - 20.745, D1 - 31.915 

2) Front End (35 W laser)
FE power: 31.9W, (measured just upstream of SL1)
Diode currents: 1/2 - 48.0A, 3/4 - 47.9A 

3) Pump diode fiber outputs (measured using NeoLase power meter)
Fibers 1,2,3,4: 32.0, 31.8, 32.9, 32.1 W

4) Visual inspection of fiber output faces
Photos of the fiber faces are attached.  Only fibers 1-4 were used; 5 an 6 are spares.
Fibers 4 and 5 looked particularly bad.

5) AOM
65.7 mW just upstream of AOM
53.7 mW just upstream of curved mirror (M16)
-> 82% single pass diffraction efficiency
40 mW just downstream of FSS EOM
-> 61% double pass efficiency
RF power at input to the AOM: 20 Vp-p (terminated into 50 ohms)

6) Reference cavity visibility (measured using RFPD DC output)
unlocked: 2.74 V
locked: 0.310 V
-> 89% visibility

7) Other measurements
drive to the FSS EOM: 244 mVp-p
power incident on FSS RFPD with loop unlocked: 34.9 mW
finesse of reference cavity (see attached photo): 9740 (estimated using 1.1 MHz/V FAST actuator coefficient measured when laser was installed)

8) Discovery
dessicated spider on optical table near mode-matching lens mount (photo attached)

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