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ID Date Author Type Category Subject
17038   Tue Jul 26 21:16:41 2022 KojiUpdateComputer Scripts / ProgramsVector fitting

I think the fit fails as the measurement quality is not good enough.

17043   Thu Jul 28 15:11:59 2022 KojiUpdateCDSToo huge script_archive

As a result of the following work, the file volume of /cvs/cds was reduced from 3.2TB to 2.2TB, and /opt/rtcds/caltech/c1/scripts was reduced from 10GB to 1.5GB

/cvs/cds/caltech/scripts_archive was cleaned up. Now the archive files are reduced to have:

• every month 1st day from 2005 to 2018/12
• every ten days (1, 11, 21) for 2019 and 2020
• everyday for 2021 and 2022

(scripts)/MEDMtab/image was deleted. I can be restore back from one of the script_archive files.

(scripts)/MC/logs/AutoLocker.log was just deleted and refreshed. For the past settings, we can refer autoburt snapshots or script_archive files.

(scripts)/Admin/n2Check.log

• It turned out that the frequency of the check was reduced to once per 10min on Sep 9th, 2021 (unelogged activity).
• The volume of the text since then was not much volume. So I deleted the lines before this date. And the file size is <7MB now.

(scripts)/ZI was moved to /cvs/cds/apps

/opt/rtcds/caltech/c1/burt/autoburt/snapshots

• 2018, 2019, 2020 snapshots were archived in tar.gz.
• These snapshots were then deleted

17047   Fri Jul 29 20:21:11 2022 KojiUpdatePSLFSSSlow/MCAutolocker issue (docker)

MCAutolocker/FSSSlow are not properly documented and not properly working.
Tidy up the script and documentation, or bring it back to megatron

I was aware that the FSSSlow was misbehaving since the shutdown upon the July power outage.
- FSS Slow servo did nothing even though the apparent settings in C1:PSL_SLOW screen looked fine and heart beat blinking
- Wanted to restart FSSSlow at megatron. Despite the login message showing how to do it, the system service does not exist anymore, because it was moved somewhere.
- Searched 40m wiki but found no info how to kill and restart it
- Found an elog. It was moved to docker on optimus ELOG 16480 . The restart procedure can only be found here. Please fix all the documentation inconsistency >> Anchal

According to this elog, the following commands need to be run for starting up MCAutolocker and FSSSlow on optimus:

cd /opt/rtcds/caltech/c1/Git/40m/scripts/MC sudo docker-compose up -d

- Problem continues. Now FSSSlow is running but only when the IMC is locked. It does not stop even when the IMC lock is lost. How can we debug docker thing?
- This is minor but the MCAutolocker log (/opt/rtcds/caltech/c1/scripts/MC/logs/AutoLocker.log) is no longer updated even though MCAutolocker is running. Was it moved somewhere?

17048   Fri Jul 29 22:37:54 2022 KojiUpdateIOOWFS investigation

I wanted to check what's wrong with the WFS.

I played with MC2 misalignment to check the error signals.
MC2 pitch and yaw misalignment optically produce a vertical translation and horizontal rotation of the cavity axis at the waist, respectively. So it is thought to be a more separated excitation of the cavity axis.
Then I noticed that WFS2 error signals in general has high (~100%) pitch-yaw coupling. So it was suspicious.

I went to the rack and found that WFS2 SEG4 RF input (labeled "8") was not completely inserted. (Attachment 1)
It seemed that the LEMO connector or the receptacle didn't latch properly anymore and could be easily pulled.
I gave some elbow grease to fix this but in vain. I ended up to use LEMO-BNC adapters which somehow offered a robust connection.

Desipite the insightful discovery, this was not the intrinsic solution to the issue. I checked the past signal history, but I don't think this loose connection caused the missing signal.

Next, I needed to go a bit deeper. The WFS sensors are supposed to be adjusted to I phase where the PDH signal maximally shows up. And all the segments are supposed to have the same sign in terms of the PDH signal.

I've unlocked the IMC and turned on MC2 tickling. This swept the cavity over the resonances.
WFS1 SEG1I~3I showed about the same waveform, but SEG4 Q shows the PDH signal rather than SEG 4 I.
Then tried the same test for WFS2. The SEG4 I signal has the sign-flipped PDH signal compared to WFS2 SEG1I-SEG3I.

I quickly adjusted the demod phase of WFS1 SEG4 and WFS2 SEG4 to correct them,

WFS1 SEG4 103.9-> -20
WFS1 SEG4 -58  -> 120

This in fact made the pitch and yaw separated but flipped (Pitch signal shows up in WFS1Y and yaw signal shows up in WFS1P. Same for WFS2)

These modifications were reverted upon my leaving.

Now things are much more subtle now. And I need to do a more careful quantitative analysis of the demodulation phases / input matrix / output matrix.

Note: It seems that I had worked on IMCWFS on Dec 21, 2016

Attachment 1: PXL_20220730_040900843.jpg
Attachment 2: PXL_20220730_041216848.jpg
17050   Sat Jul 30 12:48:18 2022 KojiUpdatePSLFSSSlow/MCAutolocker issue (docker)

> it only starts working when C1:IOO-MC_LOCK is 1 and C1:PSL-FSS_SLOWLOOP is 1.

- OK. Your new MCAutolocker does not reflect the lock status to C1:IOO-MC_LOCK. This causes FSS Slow to go crazy when the IMC is not locked. Can you fix that?

- So C1PSL_SLOW.adl screen, which spawns by the "SLOW Servo" button on the FSS screen, has no effect on the FSS SLOW servo anymore. It is obsolete. At least the screen (or the link to the screen) should be removed. (Work on it once you are back.)

- Also, please make a wiki page and copy the description on the previous page.

17053   Tue Aug 2 01:10:26 2022 KojiUpdateIOOWFS investigation

Continued to work on the WFS repair

- Use the PDH signal to adjust the demodulation phase to have uniform signals between the segments.

- Excited laser frequency at 1234Hz by injecting 10mVpp into IMC Servo Board IN2. The input was enabled on the MC Servo screen and given the input gain of 0dB.

- Looked at the ~real time spectrum in WFS1/2 SEG1/2/3/4 I&Q after the phase rotators. Changed the demod phases 1) to have ~0deg transfer function between C1:IOO-MC_F to C1:IOO-WFSi_Ij 2) to minimize the freq signal in Q phases.
(See Attachment 1)

- Resulting change of the demod phases:

WFS1 SEG1  52.0 -> 38.0deg
WFS1 SEG2  54.0 -> 53.0deg
WFS1 SEG3  16.6 -> 33.2deg
WFS1 SEG4 103.9 ->-37.1deg

WFS2 SEG1  17.0 -> 57.8deg
WFS2 SEG2  26.6 -> 51.5deg
WFS2 SEG3  24.5 -> 44.0deg
WFS2 SEG4 -58.0 ->103.7deg

SEG4 of both WFSs had significant phase rotation. A quick check of the power spectrum indicates that the Q signals have significantly (<x1/10) lower signals (Attachment 2/3/4). So that's good.

Transfer function measurement

Now the ASCPIT/ASCYAW of the MC1/2/3 suspension were excited and the transfer functions to WFS1/2 SEG1/2/3/4 and MC Trans P/Y were measured. The analysis will come later.

Again here the Q signals have significantly lower sensitivity to the mirror motion. So it is consistent with the above observation of the spectra.

However, the quick check of the transfer functions indicated that the conventional input matrices result in the flipped dependence of the combined error signals in pitch and yaw.
This might indicate that some of the cables were not inserted into the demod board properly although the cables at the demod boards show no indication of anomaly. (See the photos in ELOG 17048)

It might be the case that the cable had been inserted with a special unusual arrangement.

In any case, this can be fixed at the input matrix. Native change of the input matrix made WFS1PIT/WFS1YAW/WFS2PIT/WFS2YAW/MC2Trans YAW servos running (after some adjustment of the servo signs).
The MC2TRANS PIT servo didn't seem to settle and run away no matter which sign is used.

It's probably better to look at the sensing matrix and figure out the proper input/output matrix carefully. So at this moment, no WFSs are working.

Note that I left the new demod phases in the system

During the transfer function measurement some filters were turned off to make the shaking smoother:

IMC ASC filters were turned off to make the FResp flat:
- MC1 ASCP/Y FM1/FM5 OFF
- MC2 ASCP/Y FM1/FM5/FM6 OFF
- MC3 ASCP/Y FM1/FM5 OFF

60Hz comb OSEM Input filters were also turned off to make the transfer functions simpler:
- MC1 INPUT FM2 OFF (60Hz comb)
- MC2 INPUT FM2 OFF (60Hz comb)
- MC3 INPUT FM2 OFF (60Hz comb)

cf. Past IMCWFS commissioning http://nodus.ligo.caltech.edu:8080/40m/12684

Attachment 1: 220801_IMC_WFS_DEMOD.pdf
Attachment 2: 220801_IMC_WFS_DEMOD2.pdf
Attachment 3: WFS1.png
Attachment 4: WFS2.png
17055   Wed Aug 3 15:01:13 2022 KojiUpdateGeneralBorrowed Dsub cables

Borrowed DSUB cables for Juan's SURF project

- 2x D25F-M cables (~6ft?)

- 2x D2100103 ReducerCables

Attachment 1: PXL_20220803_215819580.jpg
17059   Thu Aug 4 21:58:18 2022 KojiUpdateIOOWFS investigation

OK... It seems that all the 6 dof of the IMC WFS servo loops were closed with some condition...

- Measured the transfer functions from ASCPIT/YAW_EXC of each suspensions to WFS segs.
- FInd the proper input matrix for PIT and YAW for WFS1 and WFS2
- Closed loops one by one => This was not so successful because the loop shape was quite conditional.
- Closed WFS1/WFS2 loops one by one only with FM4 (0.8Hz Zero / (100Hz pole)^2). Adjust the gains to have the UGF at a few Hz.

- Found that the separation between WFS1P and WFS2P was not good. This caused instability of these loops when the gains were matched. I ended up lowering the gain of WFS1P by a factor of 10. This made the loop OK to work. FM3 (Integrator below 0.8Hz) worked fine.

- FM9 Rolloff filters (RLP12) makes the loops unstable.

- The MC2 spot loops (MC2_TRANS_PIT/YAW) are supposed to be slow loops. From the time series behavior it looks they are working.

MEDM Snapshots (Attchaments 1~4)

Attachment 1: Screenshot_2022-08-04_22-10-57.png
Attachment 2: Screenshot_2022-08-04_22-11-16.png
Attachment 3: Screenshot_2022-08-04_22-11-53.png
Attachment 4: Screenshot_2022-08-04_22-12-39.png
17060   Thu Aug 4 22:14:20 2022 KojiUpdateIOOWFS investigation

Sensing matrix measurement

MCx_ASCyyy_EXC was shaken with the amplitude of 3000 cnt. Measure the transfer functions to each segment of the WFS I&Q demod outputs.

- Pitch excitations consistently indicated WFS1 SEG2&3 / SEG1&4, and WFS2 SEG 1&2 / SEG 3&4 are the pairs.
- Yaw excitations consistently indicated WFS1 SEG1&2 / SEG3&4, and WFS2 SEG 1&4 / SEG 2&3 are the pairs.

---> WFS1P matrix {1,-1,-1,1}, WFS1Y matrix {1,1,-1,-1}, WFS2P matrix {1,1,-1,-1}, WFS2Y matrix {-1,1,1,-1}

Now look at the servo input. The following lists show the important numbers for the actuation to sensor matrices. The numbers were the measured transfer function between 7~10Hz and the unit is 1/f^2 [cnt/cnt].

CHA:, C1:SUS-MC1_ASCPIT_EXC, CHB:, C1:IOO-WFS1_I_PIT_OUT, -77.4602 +/- 18.4495 CHA:, C1:SUS-MC1_ASCPIT_EXC, CHB:, C1:IOO-WFS2_I_PIT_OUT, -22.6042 +/- 5.289 CHA:, C1:SUS-MC1_ASCPIT_EXC, CHB:, C1:IOO-MC_TRANS_PIT_OUT, -0.0007949 +/- 0.00019046 CHA:, C1:SUS-MC1_ASCYAW_EXC, CHB:, C1:IOO-WFS1_I_YAW_OUT, -60.5557 +/- 14.1008 CHA:, C1:SUS-MC1_ASCYAW_EXC, CHB:, C1:IOO-WFS2_I_YAW_OUT, -206.3526 +/- 47.1332 CHA:, C1:SUS-MC1_ASCYAW_EXC, CHB:, C1:IOO-MC_TRANS_YAW_OUT, 0.00027094 +/- 6.6131e-05

CHA:, C1:SUS-MC2_ASCPIT_EXC, CHB:, C1:IOO-WFS1_I_PIT_OUT, 57.8636 +/- 35.3874 CHA:, C1:SUS-MC2_ASCPIT_EXC, CHB:, C1:IOO-WFS2_I_PIT_OUT, -185.079 +/- 104.679 CHA:, C1:SUS-MC2_ASCPIT_EXC, CHB:, C1:IOO-MC_TRANS_PIT_OUT, 0.00089367 +/- 0.00052603 CHA:, C1:SUS-MC2_ASCYAW_EXC, CHB:, C1:IOO-WFS1_I_YAW_OUT, -349.7898 +/- 202.967 CHA:, C1:SUS-MC2_ASCYAW_EXC, CHB:, C1:IOO-WFS2_I_YAW_OUT, -193.7146 +/- 111.2871 CHA:, C1:SUS-MC2_ASCYAW_EXC, CHB:, C1:IOO-MC_TRANS_YAW_OUT, 0.003911 +/- 0.0023028

CHA:, C1:SUS-MC3_ASCPIT_EXC, CHB:, C1:IOO-WFS1_I_PIT_OUT, 65.5405 +/- 14.305 CHA:, C1:SUS-MC3_ASCPIT_EXC, CHB:, C1:IOO-WFS2_I_PIT_OUT, 78.8535 +/- 17.1719 CHA:, C1:SUS-MC3_ASCPIT_EXC, CHB:, C1:IOO-MC_TRANS_PIT_OUT, -0.00087661 +/- 0.00020837 CHA:, C1:SUS-MC3_ASCYAW_EXC, CHB:, C1:IOO-WFS1_I_YAW_OUT, -130.7286 +/- 29.6898 CHA:, C1:SUS-MC3_ASCYAW_EXC, CHB:, C1:IOO-WFS2_I_YAW_OUT, 129.0654 +/- 28.6328 CHA:, C1:SUS-MC3_ASCYAW_EXC, CHB:, C1:IOO-MC_TRANS_YAW_OUT, -0.00024944 +/- 5.9112e-05

Put these numbers in the matrix calculation and take the inverse for pitch and yaw separately.

We obtained

WFS1P    WFS2P    MCTP     -4.017   -4.783   -7.306e5   MC1P  3.611   -5.252   -2.025e5   MC2P  7.323   -1.017   -6.847e5   MC3P

WFS1Y    WFS2Y    MCTY     -3.457   -4.532   -5.336e5   MC1Y -0.1249   0.3826   2.635e5   MC2Y -5.714    1.076   -4.578e5   MC3Y

Basically we can put these numbers into the output matrix. The last column corresponds to the spot position servo and we want to make this slow. So used x1e-5 values (i.e. removed e5) instead of these huge numbers.

Attachment 1: IMC_SUS_channels_TF.pdf
Attachment 2: IMC_WFS_channels_TF.pdf
Attachment 3: IMC_WFS_segment_TF.pdf
Attachment 4: IMC_WFS_220804.xlsx
17061   Thu Aug 4 22:14:38 2022 KojiUpdateIOOWFS investigation

WFS/MCTRANS_QPD Power Spectra

Attachment 1: HEPA ON

WFS1/2 PIT/YAW Spectra are stabilized below 1Hz (0.1Hz for WFS1P)

MC2 TRANS PIT is largely contaminated by the other WFS loops.
MC2 TRANS YAW is slightly contaminated but not much compared to the one for pitch.

Attachment 2: HEPA OFF

Again, WFS1/2 PIT/YAW Spectra are stabilized below 1Hz (0.1Hz for WFS1P)

MC2 TRANS PIT is still contaminated but better.
MC2 TRANS YAW is not contaminated.

Observation

WFS1/2 signals are largely disturbed when PSL HEPA is ON. Probably the amount of HEPA air flow was not optimized.
Above 1Hz, invacuum suspension are quieter than the beam incident on the IMC.

The dirty WFS signals are fedback to the mirrors. Due the large motion of the beam and also the imperfection of the actuator matrix cause the MC2 spot rather moves than stabilized.

This means that the WFS loops should leave the mirrors untouched above 1Hz i.e. The loop bandwidths should be low (~<0.1Hz). (Yes I know)
However, the simple gain reduction (x10) does make the servos unstable. So more adjustment is necessary. (<-Not for today)

Attachment 1: Screenshot_2022-08-04_22-17-19.png
Attachment 2: Screenshot_2022-08-04_22-18-45.png
17062   Thu Aug 4 22:32:31 2022 KojiUpdateIOOUpon leaving the lab (WFS investigation)

Upon leaving the lab:

- HEPA is ON at the original speed (i.e. same speed at 5PM today)

- WFS servo is ON, partly because we want to see how stable it is. It is not handled with the autolocker right now.
So there is a possibility that the WFS servo goes wild and make the IMC totally misaligned (and does not come back)
In such a case, go to the WFS servo screen and push "CH" (clear history) of each servo filters.

17063   Fri Aug 5 12:42:12 2022 KojiUpdateIOOIMC WFS: Overnight observation

The IMC lock survived overnight and the WFS servo loops kept it aligned. The IMC was unlocked in the morning.
The left 6 plots are the WFS servo outputs and the right most two plot show the transmission and reflection of the IMC.

If the WFS is making the lock unstable under high seismic conditions, please turn the loops off.

Attachment 1: Screen_Shot_2022-08-05_at_12.04.01.png
17068   Tue Aug 9 15:50:22 2022 KojiUpdateBHDBHD fringe contrast improved from 43% to 74%

For both 40m/17020 and 40m/17024, what does the contrast mean if the numbers are leaking out to ~-100cnt?
Also how much is it if you convert this contrast into the mode matching?

17072   Wed Aug 10 19:36:45 2022 KojiBureaucracyGeneralLab cleaning and discovery

During the cleaning today, we found many legacy lab items. Here are some policies what should be kept / what should be disposed

Dispose

• VME crates and VME electronics as long as they are not in use
• Eurocard SUS modules that are not in use.
• Eurocard crates (until we remove the last Eurocard module from the lab)
• Giant steel plate/palette (like a fork lift palette) along the Y arm. (Attachment 1)
• An overhead projector unit.

Keep

• Spare Eurocard crates / ISC/PZT Eurocard modules
• Boxes of old 40m logbooks behind the Y arm (see Attachment 2/3).
• Ink-plotter time-series data (paper rolls) of 1996 IFO locking (Attachment 4). Now stored in a logbook box.
• A/V type remnants: Video tapes / video cameras / casette tapes as long as they hold some information in it. i.e. Blank tapes/blank paper rolls can be disposed.
Attachment 1: steel_plate.jpg
Attachment 2: logbook1.jpg
Attachment 3: logbook2.jpg
Attachment 4: paper_plots.jpg
17077   Fri Aug 12 02:02:31 2022 KojiUpdateGeneralPower Outage Prep: nodus /home/export backup

Took the backup (snapshot) of /home/export as of Aug 12, 2022

controls@nodus> cd /cvs/cds/caltech/nodus_backup controls@nodus> rsync -ah --progress --delete /home/export ./export_220812 >rsync.log&

As the last backup was just a month ago (July 8), rsync finished quickly (~2min).

17079   Mon Aug 15 10:27:56 2022 KojiUpdateGeneralRecap of the additional measures for the outage prep

[Yuta Koji]

(Report on Aug 12, 2022)

We went around the lab for the final check. Here are the additional notes.

• 1X9: The x-end frontend machine still had the AC power. The power strip to which the machine is connected was disconnected from the AC at the side of the rack. (Attachment 1)
• 1X8: The vacuum rack still supplied the AC to c1vac. This was turned off at the UPS. (Attachment 2)
• 1X6: VMI RFM hub still had the power. This was turned off at the rear switch. (Attachment 3)
• PSL: The PSL door was open (reported above). Closed. (Attachment 4)
• 1Y2: The LSC rack still had the DC power. The supplies were turned off at the KEPCO rack (the short rack). (Attachment 5)
Note that the top-right supply for the +15V is not used. (The one in the empty slot got busted). We may need some attention to the left-most one in the second row. It indicated a negative current. Is this just the current meter problem or is the supply broken?
• Control room: The CAD WS was turned off.

I declare that now we are ready for the power outage.

Attachment 1: PXL_20220812_234438097.jpg
Attachment 2: PXL_20220812_234655309.jpg
Attachment 3: PXL_20220812_234748559.jpg
Attachment 4: rn_image_picker_lib_temp_b5f3e38d-796c-4816-bc0e-b11ba3316cbe.jpg
Attachment 5: PXL_20220812_235429314.jpg
17082   Mon Aug 15 20:09:18 2022 KojiUpdateGeneralc1vac issues, 1 pressure gauge died

- Disk Full: Just use the usual /etc/logrotate thing

- Vacuum gauge

I rather feel not replacing P1a. We used to have Ps and CCs as they didn't cover the entire pressure range. However, this new FRG (=Full Range Gauge) does cover from 1atm to 4nTorr.

Why don't we have a couple of FRG spares, instead?

Questions to Tega: How many FRGs can our XGS-600 controller handle?

17084   Wed Aug 17 01:18:54 2022 KojiUpdateGeneralNotice: SURF SUS test setup blocking the lab way

Juan and I built an analog setup to measure some transfer functions of the MOS suspension. The setup is blocking the lab way around the PD test bench.
Excuse us for the inconvenience. It will be removed/cleared by the end of the week.

Attachment 1: PXL_20220817_060428109.jpg
17091   Thu Aug 18 18:10:49 2022 KojiSummaryLSCFPMI Sensitivity

The overlapping plot of the calibrated error and control signals gives you an approximately good estimation of the freerun fluctuation, particularly when the open-loop gain G is much larger or much smaller than the unity.
However, when the G is close to the unity, they are both affected by "servo bump" and both signals do not represent the freerun fluctuation around that frequency.

To avoid this, the open-loop gain needs to be measured every time when the noise budget is calculated. In the beginning, it is necessary to measure the open-loop gain over a large frequency range so that you can refine your model. Once you gain sufficient confidence about the shape of the open-loop gain, you can just use measurement at a frequency and just adjust the gain variation (most of the cases it comes from the optical gain).

I am saying this because I once had a significant issue of (project-wide) incorrect sensitivity estimation by omitting this process.

17093   Fri Aug 19 15:20:14 2022 KojiUpdateGeneralNotice: SURF SUS test setup blocking the lab way

The setup was (at least partially) cleared.

Attachment 1: PXL_20220819_201318044.jpg
17095   Fri Aug 19 15:36:10 2022 KojiUpdateGeneralSR785 C21593 CHA+ BNC broken

When Juan and I were working on the suspension measurement, I found that CHA didn't settle down well.

I inspected and found that CHA's + input seemed broken and physically flaky. For Juan's measurements, I plugged + channels (for CHA/B) and used - channels as an input. This seemed work but I wasn't sure the SR functioned as expected in terms of the noise level.

We need to inspect the inputs a bit more carefully and send it back to SRS if necessary.

How many SR785's do we have in the lab right now? And the measurement instruments like SR785 are still the heart of our lab, please be kind...

Attachment 1: PXL_20220819_195619620.jpg
Attachment 2: PXL_20220819_195643478.jpg
17114   Wed Aug 31 00:32:00 2022 KojiUpdateGeneralSOS and other stuff in the clean room

Salvage these (and any other things). Wrap and double-pack nicely. Put the labels. Store them and record the location. Tell JC the location.

Attachment 1: PXL_20220831_015137480.jpg
Attachment 2: PXL_20220831_015203941.jpg
Attachment 3: PXL_20220831_015230288.jpg
Attachment 4: PXL_20220831_015249451.jpg
Attachment 5: PXL_20220831_015424383.jpg
Attachment 6: PXL_20220831_015433113.jpg
17115   Wed Aug 31 00:46:56 2022 KojiUpdateGeneralVertex Lab area to be cleaned

As marked up in the photos.

Attachment 5: The electronics units removed. Cleaning half way down. (KA)

Attachment 6: Moved most of the units to 1X3B rack ELOG 17125 (KA)

Attachment 1: PXL_20220831_015758208.jpg
Attachment 2: PXL_20220831_015805113.jpg
Attachment 3: PXL_20220831_015816628.jpg
Attachment 4: PXL_20220831_015826533.jpg
Attachment 5: PXL_20220831_015844401.jpg
Attachment 6: PXL_20220831_015854055.jpg
Attachment 7: PXL_20220831_015903704.jpg
Attachment 8: PXL_20220831_015919376.jpg
Attachment 9: PXL_20220831_021708873.jpg
17116   Wed Aug 31 01:22:01 2022 KojiUpdateGeneralAlong the X arm part 1

Attachment 5: RF delay line was accommodated in 1X3B. (KA)

Attachment 1: PXL_20220831_015945610.jpg
Attachment 2: PXL_20220831_020024783.jpg
Attachment 3: PXL_20220831_020039366.jpg
Attachment 4: PXL_20220831_020058066.jpg
Attachment 5: PXL_20220831_020108313.jpg
Attachment 6: PXL_20220831_020131546.jpg
Attachment 7: PXL_20220831_020145029.jpg
Attachment 8: PXL_20220831_020203254.jpg
Attachment 9: PXL_20220831_020217229.jpg
17117   Wed Aug 31 01:24:48 2022 KojiUpdateGeneralAlong the X arm part 2

Attachment 1: PXL_20220831_020307235.jpg
Attachment 2: PXL_20220831_020333966.jpg
Attachment 3: PXL_20220831_020349163.jpg
Attachment 4: PXL_20220831_020355496.jpg
Attachment 5: PXL_20220831_020402798.jpg
Attachment 6: PXL_20220831_020411566.jpg
Attachment 7: PXL_20220831_020419923.jpg
Attachment 8: PXL_20220831_020439160.jpg
Attachment 9: PXL_20220831_020447841.jpg
17118   Wed Aug 31 01:25:37 2022 KojiUpdateGeneralAlong the X arm part 3

Attachment 1: PXL_20220831_020455209.jpg
Attachment 2: PXL_20220831_020534639.jpg
Attachment 3: PXL_20220831_020556512.jpg
Attachment 4: PXL_20220831_020606964.jpg
Attachment 5: PXL_20220831_020615854.jpg
Attachment 6: PXL_20220831_020623018.jpg
Attachment 7: PXL_20220831_020640973.jpg
Attachment 8: PXL_20220831_020654579.jpg
Attachment 9: PXL_20220831_020712893.jpg
17119   Wed Aug 31 01:30:53 2022 KojiUpdateGeneralAlong the X arm part 4

Behind the X arm tube

Attachment 1: PXL_20220831_020757504.jpg
Attachment 2: PXL_20220831_020825338.jpg
Attachment 3: PXL_20220831_020856676.jpg
Attachment 4: PXL_20220831_020934968.jpg
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17120   Wed Aug 31 01:53:39 2022 KojiUpdateGeneralAlong the Y arm part 1

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17121   Wed Aug 31 01:54:45 2022 KojiUpdateGeneralAlong the Y arm part 2
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17125   Wed Aug 31 16:11:37 2022 KojiUpdateGeneralVertex Lab area to be cleaned

The analog electronics units piled up along the wall was moved into 1X3B rack which was basically empty. (Attachments 1/2/4)

We had a couple of unused Sun Machines. I salvaged VMIC cards (RFM and Fast fiber networking? for DAQ???) and gave them to Tega.
Attachment 3 shows the eWastes collected this afternoon.

Attachment 1: PXL_20220831_224457839.jpg
Attachment 2: PXL_20220831_224816960.jpg
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17162   Wed Sep 28 19:15:56 2022 KojiUpdateGeneralTesting 950nm laser found in trash pile

I don't know what was wrong with the past setup but the 950nm laser (QPHOTONICS QFLD-950-3S) just worked fine up to ~300MHz with basically the same setup.

A 20dB coupler picks up a small amount of the driving signal from the source signal of the network analyzer. This was fed to CHR. The fiber-coupled NewFocus PD RF output was connected to CHA.
The calibration of the response was done with the thru response (connect the source signal to the CHA via all the long cables).

Attachment 1 shows the response CHA/CHR. The output is somewhat flat up to 20MHz and goes down towards 100MHz, but still active up to 500MHz as long as the normalization with the New Focus PD works.
The structure around 200MHz~300MHz changes with how the wires of the clips are arranged. I have twisted and coiled them as shown and the notch disappeared. For the permanent setup we should keep the lines as short as possible and take care of the stray capacitance and the inductance.

Attachment 2 shows the setup at the network analyzer side. Nothing special.

Attachment 3 shows the setup at the laser side. The DB9 connector on the Jenne's laser has the negative output of the LD driver connected to the coax core and the positive output connected to the shield of the coax. Therefore the coax core (red clip) has to be connected to Pin 9 and the coax shield (black clip) to PIn 5.

Attachment 1: PXL_20220929_013850989.MP.jpg
Attachment 2: PXL_20220929_013859439.jpg
Attachment 3: PXL_20220929_013911125.jpg
10682   Thu Nov 6 14:41:49 2014 KoijUpdateLSC3F RFPD RF spectra

That's not what I'm asking.

Also additional cables are left connected to the signal path. I removed it.

3540   Tue Sep 7 23:34:15 2010 Kiwamu, SanjitConfigurationComputerse-log

e-log was repeatedly hanging and several attempts to start the daemon failed.

problem was solved after clearing the (firefox) browser cache, cookie, everything!!

1363   Fri Mar 6 01:04:49 2009 Kiwamu IZUMIConfigurationIOO!! lock-in amp disconnected !!

The power supply of a lock-in amp, which is on the Y-arm side of PSL clean room, was pulled out by my mistake.

Then I reconnected it, but I don't know whether it is re-adjusted properly.

I'm sorry about this. If you are using that amp, it should be checked.

1326   Thu Feb 19 22:40:33 2009 KiwamuUpdateElectronicsPSL angle QPD

I checked a broken QPD, which was placed for PSL angle monitor, and finally I cocluded one segment of the quadrant diode was broken.

The broken segment has a offset voltage of -0.7V after 1st I-V amplifier. It means the diode segment has a current offset without any injection of light.

Tomorrow I will check a new QPD for replacement.

Kiwamu IZUMI

13183   Thu Aug 10 14:13:23 2017 KiraSummaryPEMtemperature sensor

Goal is to build a temperature sensor accurate to 1 mK. Schematic is shown below. This does not take into account the DC gain that occurs.

Parts that would be used for this: LM317 regulator, AD592 temperature transducer, OP amp (low input noise and high impedance), 100K (or maybe 10k) resistor. This is what is currently proposed, but the exact parts we use could be changed to better fit the sensor. The resistor and the OP amp will be decided depending on the output of the AD592.

Once this is built, I would like to create a few copies of it and put them into an insulated container and measure the output from each one. This would allow us to calculate the temperature noise of the circuit, as we can take out the variations due to temperature changes inside the container by comparing the outputs.

I can also model the noise in the circuit to see how much noise there is before building it. There are three terms to the noise that we have, and we need to decide which one dominates at low frequencies.

Our final goal is to create an additional circuit that could cancel out the DC gain. I have attached an additional schematic proposed by Rana that would help with this issue. I will leave this second half for when the first part works.

Attachment 1: IMG_20170810_121637~2.jpg
Attachment 2: IMG_20170810_134422~2.jpg
13184   Thu Aug 10 14:14:17 2017 KiraUpdatePEMpreviously built temp sensor

I decided to see what was inside the sensor that had been previously made. According to elog 1102, the temperature sensor is LM34, the specs of which can be found here:

The wiring of this sensor confused me, as it appears that the +Vs end (white) connects to the input, but both the ground (left) and the Vout (middle) pins are connected to the box itself. I don't see how the signal can be read.

Attachment 1: IMG_20170810_112315.jpg
13190   Fri Aug 11 10:27:49 2017 KiraUpdatePEMtemperature sensor

Since there seems to be little difference between AD590 and AD592, I guess we could just go with the AD590. The temperature noise spectrum in the first graph are for the AD590, so if we want to reproduce those results, we should use AD590.

For the AD581/AD587, we could go with a few varieties that have the least output voltage drift, although I am not sure what precision we will need. So maybe we could try AD587U and AD581L. We could also try AD587K and AD581K and see if those work as well.

We will also need to calibrate the sensor, as it takes an input of 5V, but the AD581/AD587 provides 10V, which will give about a 1 degree error according to the datasheet. It does state that this is only a calibration error, so it shouldn't be too much of an issue.

I will figure out the packaging once I construct the sensor and verify that it works. Maybe we could use a box similar to the existing sensor, but it depends on the size of the finished circuit.

13191   Fri Aug 11 10:48:39 2017 KiraUpdatePEMtemperature sensor

Quick update: we actually have AD587KRZ and AD592, so we could start by using that and seeing how it works.

13194   Fri Aug 11 12:27:25 2017 KiraUpdatePEMtemperature sensor

Used AD592CNZ and AD586 (5V output) to create a circuit that works and is responsive to temperature changes. At room temp, using ~1K resistor, it showed ~0.3V across it, as expected. The voltage went up when we heated it with a heating gun. Next step will be to add in an OP amp and design some experiments to check to see how accurate it is. Thanks to Gautam for helping me with it!

I have attached the working circuit and a close up of the connections.

Attachment 1: IMG_20170811_121608.jpg
Attachment 2: IMG_20170811_121619.jpg
13202   Mon Aug 14 09:49:18 2017 KiraUpdatePEMtemperature sensor

Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating.

I've attached a few pictures showing the circuit.

Attachment 1: IMG_20170814_092452.jpg
Attachment 2: IMG_20170814_092513.jpg
13203   Mon Aug 14 12:52:33 2017 KiraUpdatePEMtemperature sensor

I didn't realize that the LT1012 needed an additional input to function. I added in +15V and -15V to pins 7 and 4, respectively and placed a 10k resistor and the numbers make more sense now. The voltage showed a negative value, but it became more negative as I heated it up (it's negative due to how a transimpedance amplifier works).

I have attached the new setup and the value it shows (~-3V). It became more negative by about 0.4V, which translates to about a 40K increase in temperature, which makes sense.

In addition, I have attached an updated sketch of the circuit. I will need to do more testing to determine how accurate this is. The next step would be to calculate how much noise there is currently and figure out how to remove this circuit from the breadboard and use a PCB or something like that for final testing in an insulated container.

The reason I chose AD743 initially for the OP amp is because at low frequencies (which is what we are working with), a FET amp such as AD743 will have a low current noise at high impedance, which is what we have in this case. While a FET amp has high voltage noise compared to other OP amps, the current noise becomes more important at high impedance, so it will work better. According to Zach's graphs, the AD743 is best at high impedances, followed by LT1012.

 Quote: Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating. I've attached a few pictures showing the circuit.

Attachment 1: IMG_20170814_121131.jpg
Attachment 2: IMG_20170814_121139.jpg
Attachment 3: IMG_20170814_121758~2.jpg
13209   Tue Aug 15 11:50:21 2017 KiraSummaryPEMtemp sensor packaging/mount

For the final packaging/mounting of the sensor to the seismometer, I have thought of two options.

1. Attach circuit to a PCB board and place it inside the can, while leaving the AD590 open to the air inside the can.

• This makes sure that the sensor gets a direct measurement of the temperature of the air in the can, as it is exposed to the air.
• But, it takes a limited area of measurement, so it could be the case that the area we place it in happens to be a hot or cold pocket, and the measurement would be inaccurate.
• This can be solved by placing multiple copies of the circuit in various places of the can and averaging the values.

2. Attach the AD590 to a copper plate with thermal paste and put it into a pomona box.

• This solves the problem of having a limited sample area the first option had, as the copper plate should have a uniform temp distribution, thus we are sampling the temp of that whole area.
• Need to make sure that the response time to the temperature variations of copper is less than the frequency that we are measuring.
• This can be calculated using equations for heat transfer (listed below).

If anyone has input on which method is preferred or any additional options that we may have, I would appreciate it.

Heat transfer:

q = k A dT / s

• k = thermal conductivity
• A = area
• dT = temperature gradient
• s = thickness

For copper, k = 401 W/mK, x = 1.27 mm, A = 2.66x10^-3 m^2 (for the particular copper plate I measured), dT = 1K (assume). Thus the heat transfer will be 839 J/s.

I'm not completely sure what to do with this yet, but it could help us decide whether the copper plate option will be useful for us.

13210   Tue Aug 15 13:32:38 2017 KiraUpdatePEMtemperature sensor

Tested to make sure that even when only the AD586 was heated that there was no change in the reading. I did so by placing the AD586 away from the rest of the circuit and blowing hot air only on it. There was, in fact, no change.

Quote:

I didn't realize that the LT1012 needed an additional input to function. I added in +15V and -15V to pins 7 and 4, respectively and placed a 10k resistor and the numbers make more sense now. The voltage showed a negative value, but it became more negative as I heated it up (it's negative due to how a transimpedance amplifier works).

I have attached the new setup and the value it shows (~-3V). It became more negative by about 0.4V, which translates to about a 40K increase in temperature, which makes sense.

In addition, I have attached an updated sketch of the circuit. I will need to do more testing to determine how accurate this is. The next step would be to calculate how much noise there is currently and figure out how to remove this circuit from the breadboard and use a PCB or something like that for final testing in an insulated container.

The reason I chose AD743 initially for the OP amp is because at low frequencies (which is what we are working with), a FET amp such as AD743 will have a low current noise at high impedance, which is what we have in this case. While a FET amp has high voltage noise compared to other OP amps, the current noise becomes more important at high impedance, so it will work better. According to Zach's graphs, the AD743 is best at high impedances, followed by LT1012.

 Quote: Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating. I've attached a few pictures showing the circuit.

13214   Wed Aug 16 16:05:53 2017 KiraUpdatePEMtemp sensor PCB

Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well.

Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is.

Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170816_154514.jpg
Attachment 2: IMG_20170816_154541.jpg
13224   Thu Aug 17 10:41:58 2017 KiraUpdatePEMtemp sensor PCB

Got it to work. One of the connections was faulty. I decided to check the temperature measured against a thermometer. The sensor showed 26.1 C, but the thermometer showed 25.8 C after I let them both cool down after heating them up. The temperature of the thermometer was dropping at the time of measurement, but the temperature of the sensor was not. This is still a rough version of the final sensor, so I'm not sure what exactly causes this discrepancy.

 Quote: Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well. Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is. Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170817_095917.jpg
13232   Mon Aug 21 13:07:08 2017 KiraUpdatePEMtemp sensor PCB

On Friday, I cleaned up the circuit so that there are only three connections needed (+15V, -15V, GND) and a BNC connector for reading the output. Today, I added in bypass capacitors. The small yellow ones are 0.1 microF ceramic, and the large ones are 100 microF electrolytic. They are used to stabilize the +15V and -15V inputs to the OP amp and minimize fluctuations, since it doesn't have a regulator for stability. I have also attached the circuit diagram for the OP amp only, where 1 are the electrolytic and 2 are the ceramic. The temperature is still about 2 degrees off, but if that difference is constant for all temperatures in our range we can just calibrate it later.

Here is a helpful link on bypass capacitors (thanks to Kevin for sending it to me).

As a note, the electrolytic capacitors do have a polarity, so it is important to place them correctly (the negative side is towards the lower voltage potential, and not always towards ground).

Quote:

Got it to work. One of the connections was faulty. I decided to check the temperature measured against a thermometer. The sensor showed 26.1 C, but the thermometer showed 25.8 C after I let them both cool down after heating them up. The temperature of the thermometer was dropping at the time of measurement, but the temperature of the sensor was not. This is still a rough version of the final sensor, so I'm not sure what exactly causes this discrepancy.

 Quote: Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well. Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is. Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170821_124121.jpg
Attachment 2: IMG_20170821_124429~2.jpg
Attachment 3: IMG_20170821_124108.jpg
13269   Tue Aug 29 15:41:17 2017 KiraSummaryPEMheater circuit

I worked with Kevin and Gautam to create a heater circuit. The first attachment is Kevin's schematic of the circuit. The OP amp connects to the gate of the power MOSFET, and the power supply connects to the drain, while the source goes into the heater. We set the power supply voltage to 22V and varied the voltage of the input to the OP amp. At 6V to the OP amp, we got a current of 0.35A flowing through the heater and resistor. This was the peak current we got due to the OP amp being saturated (an increase in either of the power supplies did not change the current), but when we increased the voltage of the supply rails of the OP amp from 15V to 20V, we got a current of 0.5A. We would want a higher current than this, so we will need to get a different OP amp with a higher max voltage rating, and a resistor that can take more power than this one (it currently takes 5W of power, and is the best one we could find).

Kevin and I created a simulation of this circuit using CircuitLab to understand why the current was so low (second attachment). The horizontal axis is the voltage we supply to the OP amp. The blue line shows the voltage at the point between the output of the OP amp and the gate of the MOSFET. The orange line is the voltage at the point between the source of the MOSFET and the heater. The brown line is the voltage at the point between the heater and resistor. Thus, we can see that saturation occurs at about 2.1V. At that point, the gate-source voltage is the difference between the blue curve and the orange curve, which is about 4V, which is what we measured. Likewise, the voltage across the heater is the difference between the orange curve and the brown curve, which comes out to around 8V, which is also what we measured. Lastly, the voltage across the resistor is the brown curve, which is about 2V, which matches our observations. The circuit works as it should, but saturates too soon to get a high enough current out of it.

Gautam noted that it is important to measure the current correctly. We can't just use an ammeter and place it across the resistor or heater, because the internal resistance of the ammeter (~0.5 ohm) is comparable to the resistance we want to measure, so the current gets split between the circuit and the ammeter and we get an equivalent resistance of 1/R = 1/R0 + 1/Ra, where R0 is the resistance of the part we want to measure the current across, and Ra is the ammeter resistance. Thus, the new resistance will be lower and the ammeter will show a higher current value than what is actually there. So to accurately measure the current, we must place the ammeter in series with the part we want to measure. We initially got a 1A reading on the heater, which was not correct, and our setup did not heat up at all basically. When we placed the ammeter in series with the heater, we got only 0.35A.

The last two images are the setup for testing of the heater. We wrapped it around an aluminum piece and covered it with a few layers of insulating material. We can stick a thermometer in between the insulation and heater to see the temperature change. In later tests, we may insulate the whole piece so that less heat gets dissipated. In addition, we used a heat sink and thermal paste to secure the MOSFET to it, as it got very hot.

Our next steps will be to get a resistor and an OP amp that are better suited for our purposes. We will also run simulations with components that we choose to make sure that it can provide the desired current of 1A (the maximum output of the power supply is 24V, and the heater is 24 ohm, so max current is 1A). Kevin is working on that now.

Attachment 1: heater_circuit.pdf
Attachment 2: simulation.png
Attachment 3: heater_setup.jpg
Attachment 4: IMG_20170829_131126.jpg
13285   Fri Sep 1 15:46:12 2017 KiraUpdatePEMtemp sensor update

I took off the AD590 and attached it to two long wires leading out from the board. This will allow us to attach the sensor to a metal block and not have to stick the whole board to it. I have also completed three identical copies of this and it's pretty much ready to be tested. According to Craig and Andrew's elog here, the sensor is very noisy and they added in a low pass filter to fix that, so that's something to consider for the final version of the circuit. I'll test what I have so far and see how that goes. We still need to figure out how to get readings from the sensors.

To attach the sensor to the metal block, I'll use some thermal paste and fasteners. I'll also put a thermometer on the block to record the actual temperature. I'll then wrap it in some insulation we have in the lab and have only some wires leading out of it to make measurements. I'll leave this setup overnight and record the outputs for about a full day. The fluctuations between the sensors will then indicate the noise of each individual sensor.

Attachment 1: IMG_20170901_144729.jpg
13292   Tue Sep 5 09:47:34 2017 KiraSummaryPEMheater circuit calculations

I decided to calculate the fluctuation in power that we will have in the heater circuit. The resistors we ordered have 50 ppm/C and it would be useful to know what kind of fluctuation we would expect. For this, I assumed that the heater itself is an ideal resistor that has no temperature variation. The circuit diagram is found in Kevin's elog here. At saturation, the total resistance (we will have a $1\Omega$ resistor instead of $6\Omega$ for our new design) will be $R_{tot}=R+R_{h}=1\Omega +24\Omega =25\Omega$. Therefore, with a 24V input, the saturation current should be $I=\frac{V_{in}}{R_{tot}}=\frac{24V}{25\Omega}=0.96A$.  Therefore, the power in the heater should be (in the ideal case) $P=I^2R{_{h}}=22.1184W$

Now, in the case where the resistor is not ideal, let's assume the temperature of the resistor changes by 10C (which is about how much we would like to heat the whole thing). Therefore, the resistor will have a new value of $R_{new}=R+50ppm/C\times 10C\times 10^{-6}=1.0005\Omega$. The new current will then be $I_{new}=\frac{V_{in}}{R_{new}}=0.95998A$ and the new power will be $P_{new}=I_{new}^{2}R_{h}=22.1175W$. So the difference in power going through the heater is about 0.00088W.

We can use this power difference to calculate how much the temperature of the metal can we wish to heat up will change. $\Delta T=\Delta P\times (1/\kappa) /x$ where $\kappa$ is the thermal conductivity and x is the thickness of the material. For our seismometer, I calculated it to be 0.012K.

ELOG V3.1.3-