Ushiba, Tamaki, Akutsu + Miyo, Miyoki (w/ help of Nakano, Enomoto, Michimura, Izumi online)
Following the Ushiba-kun's (maybe). Related to 6055.
Abstract
Confirmed the sensitivity of the lens GrL3 displacement to the beam mode on the POP table, and also the image with the TMSX Gr GigE camera.
Details
After handing over to me from Ushiba-kun and Tamaki-kun about the setup for beam profiling on the POP table, such as tentative pick-off mirrors and beam profiler (this time Cinogy CMOS-1203), I somehow measured beam profiles:
- Before touching the translation stage of the lens GrL3 (the naming convension follows Fig. 6.7 in Yokogawa M-thesis).
- After touching it; the lens was 8-mm away from the nominal positon of the case 1.
See Fig. 1; "nominal" is the case 1, and "shited" is 2. The horizontal axis is the distance (hopefully... I may missed 25 mm, i.e. a hole on the optics table) from the lens GrL3.
Precisely speaking, the procedure was as follows:
- Measured the beam profiler before touching the lens GrL3's translation stage (the case 1 above)
- Removed the pick off mirror brought by Ushiba-kun, and ask Miyo-kun to sweep (if necessary) PR3 to find the beam spot in the TMSX Gr GigE camera
- Touched the GrL3's translation stage. The nominal (starting) value of the attached micrometer was 18.09 mm (Fig. 2). I firstly move this to ~ 16mm then the translation stage touched to a fork for the periscope (Fig. 3), so I could not move in this direction any more. And the beam spot in the Xend could be seen.
- Then I moved the translation stage in the opposite direction, then the micrometer read was about 26 mm (Fig. 4); so 26-18 = about 8 mm away from the nominal position. The beam could still be seen in the TMSX GigE camera (Fig. 5).
- Then I got back the pick-off mirror again in-between GrL3 and HBS, and measured the beam profile (the case 2 above)
- I left the site, so the GrL3 has been "shifted".
So we leaned that
- The GrL3's position is insensitive to the beam alignment as the beam spot has been seen. The translation stage moves along the moving direction. Nice.
- The beam mode would be sensitive to the level shown in Fig. 1.
- The fit results shown in Fig. 1 are close to those in 6055 but not fully consistent, maybe. Did I miss additonal 25 mm or so?
O..K.....
