(Uchiyama, Miyakawa, remote: Tanaka)
First, we swapped the fiber laser setting to the neoLASE setting this morning. A mirror on the X-axis stage to merge the light was shifted to select the neoLASE path. We aligned to PMC and locked PMC and IMC to the neoLASE laser with 20W input. Tests I show below will be the final test of the current master laser of neoLASE.
- First, we measured the frequency noise of neoLASE. What we measured on 10/8 seemed to be with ~9kHz PMC UGF. Fig. 1 shows the comparison between today and 10/8. It looks that today's data shows lower frequency noise above 1kHz. It was measured with 4kHz PMC UGF (Fig.2). 10dB gain between IN1 and IN2 in the PMC circuit exists, so the gain at -10dB shows the correct UGF. I guess we forgot the 10dB gain on the 10/8's measurement. When I added another 10dB gain on the servo, which made 9kHz UGF correspond to the 10/8's noise. Anyway, they correspond below 1kHz and are still 3 times noisier than the FB laser.
- We looked at the effect of the scattering light by shaking a sensor card around the amplifier, especially around the bright location looked at by the sensor card. However, we did not see any frequency noise enhancement on both PMC and IMC error signals.
- When we looked at the spectrum of intensity noise of neoLASE, we saw moving peaks in the intensity noise as we had seen at Toyama Univ (Fig. 2). However, it was difficult to see the coherence between the position of peaks and the frequency noise.
We left the trials above because they can be seen after swapping the master laser. And, we started preparing for swapping the master laser of neoLASE. I put two bars to keep the position of the board below the laser head (Fig. 3), and set a camera to keep the beam position for swapping (Fig. 4).
We are ready to swap the master laser, but we did not have enough time to finish it today. So we leave ~20W neoLASE on and keep PMC and IMC locked over the night to see the final stability of the current master laser.
