The air conditioner was switch to warm up mode last week. After that, I found green injection direction was changed a lot. The green beam references on the PR/BS chamber are fine (as shown in the figure 1). But the green beam was quite far from good height on the first target in the arm (as shown in the figure 2 and 3).

Therefore, I checked the PR/BS oplev signals (as shown in the figure 4). From this figure, we see that mainly PR pitch was moved a lot. Additionally, BS pitch also moved in the direction. This movement is so large, so I used picomotor to recover PR position.  After recovering PR pitch, BS was moved up with oplev. With good alignment, the green beam on the first target is shown in the figure 5 and 6. However, after locking FC, the GR DC tra was found to be only around 3000.

I checked green power before AOM, it was only about 30mW, but the nominal value should be 52mW. So I changed SHG temperature from 3.096 to 3.068. Note that 3.068 makes SHG have a local maximum green output, which gives 52mW before AOM. The AOM modulation depth is 5.5dBm, which gives 14.5mW injected into FC.

Besides, recently we have SHG output oscillation problem. This is due to the gain of SHG servo is smaller than 2.25. After I put the SHG servo gain back to 2.25, oscillation disappeared.