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LAS (bKAGRA laser)
takafumi.ushiba - 17:40 Tuesday 21 October 2025 (35385) Print this report
Replacement of pump LDs from 2nd FIB amp. to the 1st

[Uchiyama, Ushiba]

Abstract:

We replced pump LDs on the 2nd fiber amplifier to the first one.
Unfortunately, the 1st FIB amplifier doesn't emit the light even if we enabled the FIB amplifier from the GUI.

Detail:

We replaced pump LDs from the snd fiber amplifier to the 1st one to recover the 1st FIB amplifier.
What we did is as follows:
1. Disconnect screws for power supply for LDs (red circle in fig1).
2. Disconnect screws to fix LDs to the cooling plate (cyab circle in fig1).
3. Disconnect fibers between LDs and amplifier (yellow circle in fig1).
4. Remove LD units from the 1st FIB amp. and install LD units from the 2nd FIB amp.

After replacement of te pump LDs, we tried to operate the 1st FIB amp. but it didn't work.
Since the situation doesn't change from that before the replacement (the FIB amp outut doesn't increase to 1W even if the FIB amp. is enabled), the power supply unit for LDs might have a problem for the 1st FIB amp.

Images attached to this report
Comments to this report:
shinji.miyoki - 3:58 Wednesday 22 October 2025 (35388) Print this report

How about using 220V AC line to wake up them?

tomotada.akutsu - 9:01 Wednesday 22 October 2025 (35389) Print this report

If the laser diode module can be detached, it might be a good idea to first check whether the proper DC supply is reaching the laser diode section with the current power source before trying 220 VAC or similar inputs.

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