[Kokeyama, Yokogawa, Sugimoto, and Enomoto; Fujii and Miyo for moving mass control]

Yeah!! It's locked!!!

The movie of TMSX_Gr camera is also attached.

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= What we did =
-- aligned ETMX so that the reflected green light comes back to POP reflection PD. When we found it, the oplev beam was slightly off in YAW.
-- went to X end and opened the GV at X end. Then good angle for ETMX slightly changed, mainly in YAW. Then we centered the QPD for ETMX TM tilt oplev.
-- came back to center area and opened the GVs (BS-ITMX, IXA-Xarm). We had to move PR3 a little bit.
-- aligned some optics on POP table using the reflection from ETMX; RF PD for Gr X, and lens and steering mirror for it.
-- aligned ITMX so that the reflection from ITMX overlaps with the incident light. We adjusted PIT first with the YAW slightly off, and then adjusted YAW by slightly exciting YAW. THEN...
-- found FLASH of X arm cavity, with both transmission PD and camera.
-- improved the alignment by looking at the camera. we mainly moved in PIT of ITMX and PR3.
-- found that the green lock loop was unintetionally closed, so opened the loop and then the flash got clearer.
-- then tried to close the green lock loop intentionally. After some trial and error, we achieved the lock of the X arm with the green laser!!!

= Note =
-- PLL for Gr X laser was important to achieve the lock; when it was not enageged, the flash was faster than when it is engaged. Thanks to the PLL, the green laser frequency is indeed stabilized.