[#INSTRM-1671] Study why the Cobra arm length were different between Sep 2021 and June 2022.

[INSTRM-1671] Study why the Cobra arm length were different between Sep 2021 and June 2022. Created: 15/Jul/22 Updated: 13/Oct/22 Resolved: 02/Oct/22
Status:	Done
Project:	Instrument control development
Component/s:	None
Affects Version/s:	None
Fix Version/s:	None

Type:

Task

Priority:

Normal

Reporter:

yuki.moritani

Assignee:

chyan

Resolution:

Done

Votes:

Labels:

EngRun

Remaining Estimate:

Not Specified

Time Spent:

Not Specified

Original Estimate:

Not Specified

Attachments:

Figure 2-2.png

Figure 3-2.png

Story Points:

Sprint:

preEngRun08Nov

Description

In the June 2021 run, the Cobra arm lengths were measured (~~INSTRM-1532~~). The result showed that the arm lengths were different from those measured in September 2021. Since the measurement on the test stand (e.g. Feb and Mar 2022, see the report in INSTRM-2532 for the details) were the same as each other, the reason for the difference on the telescope needs to be studied.

At the ICS/PFI+MCS telecon on 8 July, the following action were suggested:

Check the variation of the arm lengths themselves across the cobras, rather than the difference between the two measurement
Re-anlyse the 2021-Sep data with the latest software and compare the results

Comments

Comment by hassan [ 11/Aug/22 ]

This requires taking more data during the Nov 2022 run when the PFI is on POpt2, on order to compare the arm length data that was taken during the June 2022 run.

Comment by chyan [ 01/Oct/22 ]

Attached is the L1/L2 arm lengths measurements of two different epochs. As we can see from the plots, the arm lengths are very consistent in two different measurements. Although the arm-length differences between bench and telescope are still unknown, yet we are confident that the system is stable on telescope. It is know the the measurement from bench comes from a very fast optical lens. It is suspected that the difference may caused by the different transformation function. At this point, I suggest we close this ticket and open another ticket if we are still interesting on the art length differences between bench and telescope.

Comment by hassan [ 02/Oct/22 ]

Closing ticket following Chi-Hung recent comment.

Generated at Sat Feb 10 16:38:10 JST 2024 using Jira 8.3.4#803005-sha1:1f96e09b3c60279a408a2ae47be3c745f571388b.

[INSTRM-1671] Study why the Cobra arm length were different between Sep 2021 and June 2022. Created: 15/Jul/22 Updated: 13/Oct/22 Resolved: 02/Oct/22