 Tue May 16 19:05:18 2017, Koji, Optics, Configuration, OMC SN002 fix - temporary optics
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| Working on the SN002 OMC fix. Checked the inventory. I think I am using C8 mirror as the new temporary CM1 and PZT24 as the new temporary CM2. |
Fri Jun 23 01:58:11 2017, Koji, Optics, General, OMC #002 Repair - CM1 gluing 6x
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[Alena, Koji]
Jun 21: Alena and Koji worked on gluing of the CM1 mirror on the OMC breadboard #002. This
is an irregular procedure. Usually, the PZT mirror subassembly is prepared before the mounting prism is glued on the breadboard. In this |
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Fri Jun 23 10:55:07 2017, Koji, Optics, General, Dust layer on black glass beam dumps?
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I wondered why the black glass beam dumps looked not as shiny as before. It was in fact a layer of dusts (or contaminants) accumulated on the surface.
The top part of the internal surface of the black glass was touched by a piece of lens tissue with IPA. The outer surface was already cleaned. IPA
did not work well i.e. Required multiple times of wiping. I tried FirstContact on one of the outer surface and it efficiently worked. So I think the internal |
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Sat Jul 1 15:29:57 2017, Koji, Optics, General, Black glass cleaning / Final bonding for the emergency repair for OMC #002
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[Alena, Koji]
Report of the work on June 30.
1. Cleaning of the black glass beam dumps |
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Thu Feb 22 20:21:02 2018, Koji, Optics, Characterization, aLIGO EOM test
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| POSTED to 40m ELOG |
 Mon Apr 2 17:27:04 2018, Koji, Optics, Characterization, aLIGO EOM test
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| 2nd optical test http://nodus.ligo.caltech.edu:8080/40m/13725 |
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Sat May 5 22:51:04 2018, Koji, Optics, General, 3IFO EOM Optical test
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| The 3IFO EOM test performed at the 40m. Result: 40m ELOG 13819 |
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Tue May 15 19:53:45 2018, Koji, Optics, General, EOM Q comparison
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Qs' were estimated with a lorentzian function (eye fit)
Current LHO EOM (final version, modulation depth measurement 2018/4/5) |
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Wed May 30 17:44:23 2018, Koji, Optics, Characterization, 3IFO EOM surface check
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3IFO EOM dark microscope images courtesy by GariLynn and Rich
Attachment1/2: Hole #1
Attachment3/4: Hole #2 |
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Sun Sep 23 19:42:21 2018, Koji, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror
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[Koji Gautam]
With Gautam's help, I ran a coating design code for an HR mirror with the standard quarter-wave design. The design used
here has 17 pairs of lambda/4 layers of SiO2 and Ta2O5 (=34 layers) with the fused silica as the substrate to realize |
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Thu Sep 27 20:19:15 2018, Aaron, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror
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I started some analytic calculations of how OMC mirror motion would add to the noise in the BHD. I want to make some prettier plots, and am adding the
interferometer so I can also compute the noise due to backscatter into the IFO. However, since I've pushed the notebook I wanted to post an update.
Here's |
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Thu Nov 1 19:57:32 2018, Aaron, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror
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I'm still not satisfied/done with the solution to this, but this has gone too long without an update and anyway probably someone else will have a
direction to take it that prevents me spinning my wheels on solved or basic questions.
The story will have to wait to be on the elog, but I've put it in the jupyter notebook. Basically: |
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Thu Jan 10 20:42:54 2019, Koji, Optics, Characterization, FSR / HOM Test of OMC SN002
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OMC SN002 = Former LHO OMC which CM1 was destroyed by the lock loss pulse in 2016. This OMC needs to be optically tested before storage.
The test items:
[done] FSR measurement with offset PDH locking (FM->AM conversion)
[done] FSR/finesse |
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Thu Jan 10 20:45:00 2019, Koji, Optics, Characterization, PZT test cable
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As OMC SN002 already has the PZTs connected to the Mighty-Mouse connector, a test cable with a female mighty-mouse connector was made.
A small imperfection: When the cable was inserted to the connector shell, I forgot to mirror the pin out. Therefore the color and pin number
do not match. |
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Sat Jan 12 22:49:11 2019, Koji, Optics, Characterization, PM-SM patch cable mode cleaning effect
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Mode cleaning capability of an optical fiber was measured. The conclusion is that the
leakage of the non-fiber mode to the fiber output is insignificant and also practically negligible.
The tested fiber was Thorlabs 5-m Polarization Maintaining Single-Mode fiber (P3-1064PM-FC-5, PM Patch Cable, PANDA, 1064 nm, FC/APC, 5m). |
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Sat Feb 2 16:17:13 2019, Koji, Optics, Characterization, Summary: OMC(001) HOM structure recalculation
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Each peak of the transfer function measurement was fitted again with a complex function:
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Sat Feb 2 20:03:19 2019, Koji, Optics, Characterization, Summary: OMC(002) HOM structure recalculation (before mirror replacement)
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OMC (002)
History: Measurement date 2013/10/11, Installed to L1 2013/XX |
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Sat Feb 2 20:28:21 2019, Koji, Optics, Characterization, Summary: OMC(003) HOM structure recalculation
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OMC (003)
History: Measurement date 2014/7/5, Stored for I1, Installed to H1 2016/8 upon damage on 002 |
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Sat Feb 2 20:35:02 2019, Koji, Optics, Characterization, Summary: OMC(002) HOM structure recalculation (after mirror replacement)
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OMC (002) after repair
History:Mirror replacement after the damage at H1. Measurement date 2019/1/10 |
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Fri Apr 5 01:07:18 2019, Koji, Optics, Characterization, OMC(002): transmitted beam images
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There was a concern that the transmission from CM1 has additional fringes. The shape of the transmitted beams from CM1, CM2, and FM2 (main) werecaptured
with WinCamD.
Indeed CM1 and CM2 have the fringes, but it does not exist in the main transmission. So it seems that the fringes are associated with the curved |
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Fri Apr 5 01:08:17 2019, Koji, Optics, Characterization, OMC(002): DCPD / QPD alignment
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The beam height in the cavity became totally different from the previous one and the shims needed to be much thicker than before. This is probably because
of the alignment of the newly-glue curved mirror.
As the beam height is 2~2.5mm higher, two shims need to be stacked. The preliminary check of the heights using the alignment disks (dummy PDs) |
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Fri Apr 5 20:50:54 2019, Koji, Optics, Characterization, OMC(002): QPD alignment
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QPD# QPD1 QPD2
Housing# #004 #008
Diode# #44 #46 |
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Mon Apr 15 21:11:49 2019, Philip, Optics, Characterization, OMC(004): PZT testing for spare OMC
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[Koji, Philip]
Today we tested the functionality of the four remaining PZTs (11,12,13 and 22) . Each PZT was placed within a collimated 500um beam.
Roughly half of the beam was blocked by the PZT. The PZT and a PD then acted as shadow sensor. Each PZT was tested with 0 and |
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Tue Apr 16 11:36:36 2019, Koji, Optics, Characterization, OMC(004): PZT testing for spare OMC 9x
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Attachment 1: Shadow sensor setup for the PZT displacement test
Attachment 2: PZT endurance test. 4 PZTs were shaken at once.
Attachment 3~5: Function generator setup 100Hz, 3.5Vpp 1.75Voffset (meant be displayed for 50Ohm load) |
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Tue Apr 16 16:35:09 2019, Koji, Optics, Configuration, OMC(004): Glass breadboard selection
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D1200105 SN006 was selected as the breadboard for OMC(004).
The reason is the best parallelism among the unused ones.
The attached is the excerpt from T1500060 with the #006 highlighted. |
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Tue Apr 16 16:52:36 2019, Koji, Optics, Configuration, OMC(004): B Mirror selection
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We are going to use B6 for the DCPD BS (BS2), and B1 for the QPD BS (BS3). Their role can not be swapped.
B6 has the best loss among the available ones, while the perpendicularity is not so critical due to the short arm.
B1 has the OK perpendicularity, while the loss is also moderately good. |
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Tue Apr 16 17:24:56 2019, Koji, Optics, Configuration, OMC(004): E Mirror selection
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We are going to use E6, E9, E11, and E14 for BS1, SM1, SM2, and SM3. They (and E18) are all very similar.
The attachment is the excerpt from T1500060 with some highlighting |
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Tue Apr 16 21:16:11 2019, Koji, Optics, Characterization, OMC(004): PZT testing for spare OMC
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After having dug into the past email, it turned out that these wires were the ones already replaced from the original teflonwires. The length of them
were confirmed to be ~19" (480mm).
Quote:
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Wed Apr 17 10:30:37 2019, Philip, Optics, General, OMC optical set-up day 1
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[Joe, Koji, Liyuan, Philip, Stephen]
Work done on 16.04.2019
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Thu Apr 18 20:47:54 2019, Joe, Optics, , OMC initial alignment and locking
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[Joe, Phillip, Koji, Stephen]
*draft post, please add anymore info if I missed something*
made initial alignment of the cavity. To do this we used the periscope mirrors to aim the incoming beam at the centre of the |
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Fri Apr 19 09:21:07 2019, Philip, Optics, , Cleaning of OMC optics
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ach[Joe, Phillip, Koji, Stephen]
Work from 17.04.2019
First contact cleaning of OMC optics |
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Fri Apr 19 11:34:19 2019, Koji, Optics, , OMC initial alignment and locking
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The spot on CM1 was found displaced by 3.4mm (horiz.) and 3.0mm (vert.) in the upper right direction looking from the face side.
The spot on CM2 was found displaced by 1.2mm (horiz.) and 1.8mm (vert.) in the upper left direction looking from the face side.
The drawing on the left side of the attachment shows the estimated misalignment when we think they all come from the curved |
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Sat Apr 20 00:50:12 2019, Koji, Optics, Characterization, OMC(004): Spot positions
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Similarly to OMC ELOG 349 the spot positions after the replacement of CM2 were measured
(Attachment 1)
Also, the spot positions after the realignment were measured. (Attachment 2) |
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Tue Apr 23 10:21:12 2019, Joe, Optics, Configuration, Moving the spots to the centre of the curved mirrors
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[Koji,Philip, Liyuan, Joe]
CM1:
We moved the curved mirrors to these positions: |
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Wed Apr 24 13:58:51 2019, Joe, Optics, Characterization, OMC power budget and UV Epoxy Bonding of BS1
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[koji,philip,joe,liyuan,stephen]
need to add spot positions.
Mirrors: PZT11,PZT22, A14, A5 |
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Thu Apr 25 15:05:19 2019, Joe, Optics, Characterization, Looking at PZT HOM spacing dependance and thinking about workflow
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[koji, joe]
The template or glass breadboard was wobbling, and we noticed that the caivty alignment became worse/better when it was pressed down. We saw
that it was the glass breadboard, so it was fixed into the transport fixture more securely. Now its alignement didn't change when it was pressed down. |
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Wed May 1 15:40:46 2019, Koji, Optics, Characterization, OMC(004): Spot positions and the scattering
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Tried a few things.
1. Replaced CM1 (PZT ASSY #10=M21+PZT#22+C12) with PZT ASSY #7 (=M1+PZT#13+C13)
We tried PZT ASSY #7 at the beginning and had the spots at almost at the top edge of the curved mirrors. As we found a particle on the bottom |
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Fri May 3 11:06:28 2019, Koji, Optics, Characterization, OMC(004): Spot positions and the scattering
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Experiment on 5/1
- CM1 right knob was moved 1div (10um) backward such that the spots were better centered on the mirrors
FM1 (A5): h=-0.2mm -> 0.4mm made the spot much darker but still it has a few scattering spots. |
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Thu May 9 17:35:07 2019, Koji, Optics, General, Alignment strategy
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Notes on the OMC cavity alignment strategy
- x3=1.17 γ + 1.40 δ, x4=1.40 γ + 1.17 δ
- This means that the effect of the two curved mirrors (i.e. gouy phases) are very similar. To move x3 and x4 in common is easy, but to do differentially |
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Thu May 9 18:10:24 2019, Koji, Optics, Characterization, OMC(004): Spot position scan / power budget
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(Now the CCD image is captured as a movie and the screen capture is easier!)
Various spot positions on CM1 and CM2 were tried to test how the transmission is dependent on the spot positions. CM1 has a
few bright spots while CM2 shows very dark scattering most of the case. Attachment 1 is the example images of one of the best alignment |
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Mon May 20 19:53:17 2019, Koji, Optics, Configuration, DCPD high power test
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We want to perform a damage test of OMC DCPDs with high power beam. The OMC DCPD is the 3mm InGaAs photodiodes with high quantum efficiency, delivered
by Laser Components.
The sites want to know the allowed input power during the OMC scan for beam mode analysis. The nominal bias voltage of the PDs is +12V. Therefore, |
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Wed May 22 07:31:37 2019, Koji, Optics, Configuration, Camera test (DCPD high power test)
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C30665 (3mm) camera test. The camera was Canon PowerShot G7X MkII. Exposure 1/15s, F 5.6, ISO 125, MF (~the closest), no zoom.
This image was taken before the beam illumination. Will tune the green lighting to have some gradient on the surface so that we can see any deformation
of the surface. |
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Thu May 23 01:42:46 2019, Koji, Optics, Characterization, C30665 high power test
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An Excelitas C30665 PD with the cap removed (SN07 in Case H slot #2) was exposed to the beam with the optical power of 1.4mW to 334mW.
After each illumination, the dark current and the dark noise level were tested. Also the photo image of the PD surface was taken each time.
- No significant change of the dark current after each illumination. |
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Thu May 23 23:27:38 2019, Koji, Optics, Characterization, IGHQEX3000 high power test
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LaserComponents IGHQEX3000 (Cage B2: Serial# B1-23) was exposed to the beam with the optical power from 1.6mW to 332mW.
After each illumination, the dark current and the dark noise level were measured. Also the photo image of the PD surface was taken each time.
- No significant change of the dark current after each illumination. |
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Tue May 28 12:14:20 2019, Stephen, Optics, General, CM PZT Assembly Debonding of EP30-2 in Acetone 8x
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[LiyuanZ, StephenA]
Downs B119
Summary: Beginning on 20 May 2019, two CM PZT assemblies were soaked in Acetone in an effort to debond the EP30-2 bonds |
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Mon Jul 1 12:38:49 2019, Koji, Optics, Characterization, A and M prisms perpendicularity measurement 6x
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[Stephen, Koji]
The perpendicularity of some of the A and M prisms were tested.
Results |
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Mon Jul 1 12:49:42 2019, Koji, Optics, Characterization, Scattering measurement of A and C mirrors
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| Liyuan's scattering measurement for the A and C mirrors. |
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Thu Aug 22 12:35:53 2019, Stephen, Optics, Characterization, Wedging of the debonded PZTs 2019 August
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Wedge and thickness measurements of PZTs 12 and 13 took place after debonding and cleaning - results are shown in the first image (handwritten post-it
format).
These thickness measurements seem to have come back thinner than previous measurements. It is possible that I have removed some PZT material |
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Fri Aug 23 11:11:44 2019, shruti, Optics, Characterization, Finding the curvature bottom
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I attempted to fit the data taken by Koji of the beam spot precession at the CCD in order to find the location of the curvature bottom in terms
of its distance (d) and angle () from the centre of the mirror. This was done using
the method described in a previous similar measurement and Section 2.1.3 of |
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Thu Aug 29 11:51:49 2019, shruti, Optics, Characterization, Wedging of the debonded PZTs - Calculation
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Using the measurements of PZTs 12,13 taken by Stephen, I estimated the wedging angle and orientation following Section 2.3.1 of T1500060. The results
can be found in Attachment1 and is summarised as follows.
For PZT 12, PZT 13 respectively: |