Today with Ronic and Daniele we attempted to lock the cavity, but the alphanov amplifier did not turn on because of an error in MMD3 (related to the third stage)
the new error is having the MMD3 error show on the alarm window of the LAL software, and having the Alarms on the line 3 of the alphanov software red for both EXT/CPU and Laser T Max (never been red before)
this is after a 2-week work stop, but the last time when Daniele changed the fiber connector it worked for 3 hours with no errors.
Ronic, is in contact with Guillaume from Alphanov to fix the issue !!!
Work scheduled all Wednesday, in hopes the issue is fixed by then.
| Manar Amer wrote: |
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Added Note: the coupling we get is at low power, only preamplifier is on (~ 300 mW)
was done at the end due to excitation of higher order modes.
Wanted to improve the fundamental first, then increase the power.
| Manar Amer wrote: |
- On Monday with Daniele,
- we did full characterization of amplifier beam @ 10% amplification, adjusted the telescope accordingly and injected into the cavity aligned and improved on the fundamental mode.
- On Tuesday with Daniele and Kevin
- I added a low pass filter between 1 - 1.9 MHz on the reflected signal, to reject the oscillator signal (33.33 MHz)
- removed the external resistors on the signal, only the internal resistance of the oscilloscope used ( transmission : 1 M ohm , Reflection : 50 ohm )
- We connected the motors to control the CEP and adjusted on them until we reached ~ 5 -10% coupling
- Images:
- 1st : showing the size of the beam just before injecting into the cavity @ 10%
- 2nd: signal with only improved alignment (not CEP adjustment yet), no low pass filter added yet
- 3rd : zoom on the signals (reflection and error) while adjusting on the CEP
- 4th :attempting to lock the cavity , after getting the max coupling using the CEP motors
Note : the voltage ranges are not the same between the images
| Manar Amer wrote: |
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Yesterday,
- we installed the second high power reflecting mirrors at the output of the amplifier.
- We aligned and installed a telescope that has adjustable distance between the 2 lenses of -100 mm, and + 200 mm, with approximate diameter at the injection window of ~ 4.5 mm.
- Amplifier was turned on only at the first stage only (output power ~ 300 mW) aligned and injected into the cavity.
- Measured the repetition frequency of the One Five oscillators, Frep = 33.326239 MHz
- Changed the FSR of the cavity to match it.
- Using the Piezo scan on the oscillator, we observed 00 Mode, Fundamental. the shape is the same
- We see transmission on the diode, but there was zero coupling observed (yet to be investigated experimentally )
- a reason could be the CEP of the oscillator ,
- bad matching of the beam waist position,
- noise from the amplifier (as we were operating it at very low power)
- additional alignment needed,
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