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takaaki.yokozawa - 7:30 Friday 04 September 2026 (37451) Print this report
Evaluation of the SR2 mirror angle
After installed the IR sensitive camera, we started the evaluation of the SR2 mirror angle.

Initial alignment for Xarm and Yarm performed.
I set the SR2 suspension to PAY_FLOAT state, ETMX, ETMY MISALIGNED state, ITMX MISALIGNED_BF state.
(single bounce from ITMY)
Close the GRX and GRY shutter.

I moved yaw direction using the IM optic align.
when I put the 10 count, the oplev yaw value moved 8 urad, so I roughly evaluated 10 count -> 8 urad in SR2.
the distance from SR2 to OMMT1 is 21,300 mm and we want to move the beam position on the OMMT1 at 50 mm, we need to move about 2.3 mrad in SR2 ~ 3,000 count to IMY optic align.
I added the +4,000 count, but we cannot see change in camera image, even I increased the IMC output from 1 W to 4 W, the situation was not changed.
and I changed to -4,000 count, but we cannot see change in camera image, I gave up this measurement today.
(OMMT2 trans QPD sum became almost zero even not moved so much)

Put the target inside the OMM chamber or increase the power to OMC (PRMI bright lock?)
Comments to this report:
takaaki.yokozawa - 14:29 Friday 04 September 2026 (37454) Print this report
I(actually not I but ChatGPT) generated the program for evaluating the difference of the png files.
With the PRX lock and this program, I will perform the similar measurement in next chance.
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takaaki.yokozawa - 12:22 Saturday 05 September 2026 (37457) Print this report
After the initial alignment of Xarm, Yarm and PRMI, I performed the SR2 angle investigation.

I set SR2 suspension to PAY_FLOAT state, requested PRX 1f lock to vertex guardian

By the capture diff script, I can find the beam position on the OMMT1 mirror as shown in pdf1.
Original picture was the 0 -256 gray scale, and just performed the subtraction between two figures, and multiplied to 30 after performing the absolute.
From the circle image and center value of the +500 and 0 case, I found the 321 IM optic align value would be center.
Same measurement performed in pitch with adding 321 count IM optic align Y, I can obtain the 150 count would be center in pdf2.

I took picture with PRX lock and without IR laser (shutter on), and confirmed the SR2 centering as shown in Fig.1.

Now, I didn't perform this change to SR2, It would be better with centering of SR2 oplev next Monday(?).
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takaaki.yokozawa - 9:03 Monday 07 September 2026 (37460) Print this report
Additional information.

Red circle is the image of black cover in front of OMMT1, with yellow was the center.
In this figure, we put the TCam mirror below the IR beam, so horizontal would be OK, but we need investigation for vertical direction.

I attached the gif image.
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takaaki.yokozawa - 13:29 Monday 07 September 2026 (37463) Print this report
I removed the camera structure from OMM chamber.
Before that, I took picture with bright image.

Fig.1. showed the image with red circle and yellow lines.
As you can see, the red circle was slightly lower than the hole in front of the black shield, but this camera was placed blow the IR beam height, it was not so strange.
Rather, circle can follow the center of the OSEM lights, I think.
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