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Entry  Sun Sep 27 14:45:45 2009, Koji, Update, PSL, SLOWscan result SLOWscan_090927.pngPages_from_miser_126_manual.png
    Reply  Sun Sep 27 15:25:58 2009, Koji, Update, PSL, SLOWscan result power_dependence.png
    Reply  Sun Sep 27 23:21:14 2009, rana, Update, PSL, SLOWscan result 
Message ID: 2008     Entry time: Sun Sep 27 14:45:45 2009     Reply to this: 2009   2010
Author: Koji 
Type: Update 
Category: PSL 
Subject: SLOWscan result 

I ran (script dir)/PSL/FSS/SLOWscan on op440m from 11:30 to 12:30 on 27th. Although Rana and later I myself set "timed bombs" for the scan, they did not work as they have probably been ran on Linux. After the scan I relocked PMC, FSS, and MZ . MC locked automatically.

Observation:

1. To keep away from the mode hop, FSS_SLOWDC is to be at around 0. The values -5 ~ -6 is the place for the power, which is my preference for now. BTW, the mode hop only appears to the PSL output (=AMPMON) is this normal?

2. The PSL output looks dependent on the NPRO wavelength. The NPRO output and the PSL output tends to be high when the FSS_SLOWDC is low (= LTMP: Laser Crystal Temp is low). Also there is a step at the LTMP where we think the mode hop is present. This may cause the daily PSL output variation which induced by the daily change of the reference cavity length.

My naive speculation is that the NPRO wavelength is too long (= hot side) for the MOPA absorption as the MOPA heads are cooled to 19deg.

3. Scanning of -10 to +10 changes the LTMP from 42-49deg. This is almost 1/10 of the NPRO capability. The manual told us that we should be able to scan the crystal temperature +/-16deg (about 30deg to 60deg).

What I like to try:
a) Change the NPRO temp to more cold side.
b) Change the MOPA head temp to a bit hot side.
c) Tweak the MOPA current (is it difficult?)

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