Date: 2024/3/12

With ShingoFujii

Abstract

• Adjusted TM position information in CAL script.
• Adjusted Pcal beam positions on ETM by using the picomotors in EXA chamber. And adjusted a little in Rx module.
• Then we could get the both Pcal beams in RxPD.
• The total optical efficiency from TxPD values to Rx value with a quick measurement was 95%, which is similler to the values in O4a (96% for path 1, and 95% for path 2)

Details

1. Used an LED light to lighting ETM from EXA chamber.
2. Took Tcam pictures to adjuste the ETM position on the picture. (fig1)
3. Block path 2 and pass path 1 to start adjustment of the path 1.
   1. Used picomotors on the mirror in EXA chamber to adjust the beam position on ETM. => After this work, we could see the beam in Rx module.
4. Block path 1 and pass path 2 to start adjustment of the path 2.
   1. Used picomotors on the mirror in EXA chamber to adjust the beam position on ETM. => After this work, we could see the beam in Rx module.
5. Pass both paths, and perfomered fine adjustment of the beam positions on ETM. (fig 2) => After this work, both beams were on the RxPD port without any other alignment adjustment.
6. Adjusted a little alignment for the mirrors in Rx module to make both beams on the center of the RxPD port.(fig 3)

Date: 2024/3/14

With Shingo Fujii

Abstract

We found the Pcal-X beam positions on ETMX shifted by about 5mm in this morning, then we recovered.
After the recovery, we took pictures to record beam position on each mirror in EXA.

Details

1. Checked the ETM position on Tcam images, and found it moved up by 20 pixels ~ 2 mm. (Fig 1)
2. Adjusted the parameters in our analysis script about the ETM position. (Fig 2)
3. Checked the Pcal beam positions on the ETM, and found they moved up by about 5mm. (Fig 3)
4. Adjusted the Pcal beams with the picomotors in EXA. (Fig 4)
5. Took pictures of beam positions on each mirror in EXA. There is no beam position near the edge of the mirror.
6. Because the ETM suspension was not enough stable to record beam pass in Tx module, we did not do it. Need to do this after closing EXC chamber or stop the air flow.

Date: 2024/3/18

With Takase-san

Abstract

• We found the side flanges (especially +y side = wall side) affected Pcal alignments. The condition (open or close) can change beam positions on RxPD by ~5mm.
• We checked the screws fixing the mirrors just before the ETM. They were tightly screwed enough.
• Additionally, we suspect that pico motor operations (~heat?) may be affecting the alignment.
  • Just after the picomotor operations, the beams moved ~2mm on the ETM during the lunch hour (~1.5h), and then they moved about 0.5mm/2h after that.

Details

• Changed ISOLATING threshold of ETMX suspension from 20 to 100, and requested ALIGNED.
• Checked the ETM position on Tcam picture. -> No change from the previous data.
• Checked the Pcal beam position on ETM -> they were about 5mm higher than the design position.
• We opened Rx side flange -> beam on RxPD did not change.
• We opened Tx side flange -> beam positions on RxPD changed.
• Checked the effect of the flanges condition on the beam position at RxPD. Both beams were about the same position on RxPD.

• With the picomotors in EXA, we adjusted beam position on ETM with closing the flanges, and took a record for the beam positions on the ETM.
• (Lunch time ~ 1.5h including move and other works. Picomoter power switch was ON during the lunch time)
• Checked the beam positions on ETM without any change. -> the beams changed by about 2mm.

• Adjusted beams with short time and turned OFF the picomotors.
• Monitored the beam positions for 2 hours.

• Note that it is difficult for the beam position estimation script to accurately estimate the positions by sub-milimater.
• Consider the above results, we think the Pico-motor operations may have affected alignment. (Effect of thermal?)
• We will check the alignment tomorrow morning again. After that we will turn OFF the Pcal-X laser for other works.

I analyzed the Tcam figure to see the beam position change (1) after the lunch time yesterday(3/18), and (2) morning today(3/19).

The movement of BEAM seems to have subsided over time.

My impression is that there is a change in alignment immediately after using the pico motor, which settles down over time.

Currently, there is no variation that can be captured by Tcam in 2 hours, but we would like to monitor for a few days.

Today morning, I took some Tcam data for this beam position monitor.

The Pcal-X state will be kept at OFS_CLOSED_LOW_POWER with the laser ON.

This morning, I also took some Tcam pictures for this topic.

Date: 2024/3/22 morning

I took Tcam images for 2 hours in this morning and summarized the data from the last alignment adjustment at 3/18 14:00.

Attached are the analysis result:

• Video made of Tcam data from 3/18 to this morning. (link)
• Graph of the estimated beam position time change. (PcalX_beam_position_time_change.png)
• Comparision with the temperature in Tx temperature. (fig_001.png)

What I found:

• Both beams moved from the last adjustment by more than 5mm on the ETM.
• The movement may have a relationship with the temperature of Tx module.
• The beam position during O4a was stable (1-2mm movement during 1 month): ref

Based on the above, the cause of the alignment change is thought to be inside the Tx module and in the area touched during the current modifications, which is the 4 mirrors? (28791_1709879731_IMG_2760.jpg)

With M.Takahashi-san

(1) We tightened the 2 screws fixing a pico for pitch of path 1-B/2-B. (IMG_3118.JPG)

• Path 1-B: I could rotate them by 90-180 degree without applying strong force.
• Path 2-B: I could rotate them by 45-90 degree without applying strong force.

(2) And, we checked the screws for the mirrors in EXA chamber. (IMG_2742.JPG)
They were not loose.
The screws on the mirror top could be tightened, and I did it just a little to check the torque.
The screws fixing the pico to the mirror mount were tightened enough. I did/could not rotate them.

After the above works, we adjusted the beams on the ETM and RxPD.
We will monitor the beam position during the weekend.

Monitoring the beam positions on the ETMX for 2.5 days.
They look stable now.

The video is updated: link
The updated graph is attached: PcalX_beam_position_time_change.png

There are sometimes skips during this monitoring period on the graph, but this may be due to the way the scattered light shines or to the analysis scripts.

I remember that some(most?) mirror mounts in the A chambers were "made" using a very unique and fantastic method:
I heard that the mounts were made by soaking Newport U300-A etc in acid? to dissolve the Anodized Aluminum coating.
 

With Takase-san

We tested how much the pico motor could move after the vacuum chamber was closed.

What we did:

1. Move pico by 50 steps

2. Adjust beam position in Rx module

3. Take Tcam picture

4. Record RxPD output

5. Go to 1.

This was done independently for the four pico motors of Pcal_EX2. 
The result is attached.
This test was performed to the point where the RxPD signal was about 95% from the reference point.
For any DOF of about 200 steps (~1cm? on the ETM), the effect is limited (<2%).

After the above work, we aligned the Pcal beams again, and took pictures of each mirror in EXA chamber with a sensor card to record the beam position.

I believe we don't have any other work related to Pcal-X before closing the vacuum chamber. 

Date: 2024/3/29

I checked the alignment change from the last alignment adjustment on 25th.
This time, I requested "ISOLATED" state to the suspension for taking the pictures.
Then I compared a picture on 3/25 taken just after the alignment adjustment, and a picture today.

• TCam_ETMX_00001_2024_0325_145559.png
• TCam_ETMX_00001_2024_0329_052158.png

I can not see any change.
Before this, I confirmed that the ETM position on the Tcam pictures did not change.

I attached a graph showing the time change of beam position analysis result.

Since the 25th, there are occasional changes of 1 or 2 mm, which are thought to be due to changes in scattered light caused by slight changes in the orientation and position of the mirror.
Overall, there appears to be no significant shift changes on the Pcal beam position.

I took some Tcam pictures with ISOLATED state for ETMX suspension.

There are no differences special with the data yesterday.

I took some Tcam pictures with ALIGNED state for ETMX suspension.

There are no differences special with the data yesterday.

I analyzed Tcam data during the weekend.

Path 2 (lower one on Tcam image) vertical may be moving?
The movement is about 2mm ~ 50urad.

I also attached 2 Tcam data on 3/25 and 4/1 for the camparison.
(The red lines on the pictures are just references on the picture data, do not mean the designed positions.)

Alignment check at RxPD between 25th March and 3rd April.

I compared pictures of the beam position on RxPD taken on 25th March and 3rd April.

The horizontal axis doesn't look to be changed.

The vertical axis looks changed by 3 or 4 mm, which is consistent with the Tcam analysis.