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ID Date Author Type Category Subject
383   Tue Oct 22 11:52:53 2019 StephenGeneralGeneralEpoxy Curing Timeline of OMC PZT Assy #9 and #10

This post captures the curing timeline followed by OMC PZT Assys #9 and #10.

Source file posted in case any updates or edits need to be made.

Attachment 1: omc_elog_383_Epoxy_Curing_Timeline_of_OMC_PZT_Assy_20191022.png
Attachment 2: omc_elog_383_Epoxy_Curing_Timeline_of_OMC_PZT_Assy.pptx
382   Tue Oct 22 10:25:01 2019 StephenGeneralGeneralOMC PZT Assy #9 and #10 Production Cure Bake

OMC PZT Assy Production Cure Bake (ref. OMC elog 381) for PZT Assy #9 and #10 started 27 September 2019 and completed 28 September 2019. Captured in the below figure (purple trace). Raw data has been posted as an attachment as well.

We have monitored the temperature in two ways:

1) Datalogger thermocouple data (purple trace).
2) Checking in on temperature of datalogger thermocouple (lavender circles) and drive thermocouple (lavender diamonds), only during initial ramp up.

• No changes were made to the tuning or instrumentation of the oven between the successful qualifying bake obtained on 26 September (ref. OMC elog 380). However, the profile seems to have been more similar to prior qualifying bake attempts that were less successful (ref. OMC elog 379), particularly as the oven seems to have ramped to an overtemperature state. I am a bit mystified, and I would like to see the oven tuning characterized to a greater extent than I have had time and bandwith to complete within this effort.
• The maximum datalogger temperature was 104 °C, and the duration of the soak (94 °C or higher) was 68 minutes. This was in contrast to a programmed soak of 2.5 hours and a programmed setpoint of 84 °C.
• The drive thermocouple did appear to be under-reporting temperature relative to the datalogger thermocouple, but this was not confirmed during the soak period. Neither thermocouple was calibrated as part of this effort.

Attachment 1: OMC_ABO_PZT_Curing_Bake_effort_201906_thru_201909.xls
Attachment 2: production_cure_bake_pzt_assys_9_and_10_20190927.png
381   Mon Sep 30 23:16:53 2019 KojiOpticsGeneralOMC(004): PZT sub-assembly gluing (#9/#10)

Friday: [Stephen, Koji]

As the oven setting has qualified, we brought the PZT assys in the air bake oven.

Monday: [Stephen, Shruti, Koji]

We brought the PZT assys to the clean room. There was not bonding between the flexture and the PZT subassy (Good!). Also the bonding o at each side looks completely wetted and looks good. The package was brought to the OMC lab to be tested in the optical setup.

Attachment 1: IMG_8950.jpeg
Attachment 2: IMG_8953.jpeg
Attachment 3: IMG_8954.jpeg
Attachment 4: IMG_8955.jpeg
380   Thu Sep 26 17:33:52 2019 StephenGeneralGeneralDirty ABO test run prior to PZT Subassembly Bonding - ABO is Ready!

Follow up on OMC elog 379

I was able to obtain the following (dark blue) bake profile, which I believe is adequate for our needs.

The primary change was a remounting of the thermocouple to sandwich it between two stainless steel masses. The thermocouple bead previously was 1) in air and 2) close to the oven skin.

Attachment 1: image_showing_20190924_abo_qualifying_bake.png
379   Tue Sep 24 12:19:20 2019 StephenGeneralGeneral Dirty ABO test run prior to PZT Subassembly Bonding

The 40m Bake Lab's Dirty ABO's OMEGA PID controller was borrowed for another oven in the Bake Lab (sound familiar? OMC elog 377), so I have had to play with the tuning and parameters to recover. This bake seemed to inadequately match the intended temperature profile for some reason (intended profile is shown by plotting prior qualifying bake for comparison).

The parameters utilized here are exactly matching the prior qualifying bake, except that the autotuning may have settled on different parameters.

Options to proceed, as I see them, are as follows:

1. reposition the oven's driving thermocouple closer to the load and attempt to qualify the oven again overnight
2. retune the controller and attempt to qualify the oven again overnight
3. proceed with current bake profile, except monitor the soak temperature via data logger thermocouple and intervene if temperature is too high by manually changing the setpoint.

Attachment 1: image_showing_20190923_abo_qualifying_bake.png
378   Mon Sep 23 21:29:51 2019 KojiOpticsGeneralOMC(004): PZT sub-assembly gluing (#9/#10)

[Stephen, Shruti, Koji]

We worked on the gluing of the PZT sub-assy (#9 and #10) along with the designed arrangement by Shruti (OMC ELOG 374).

The detailed procedures are described in E1300201 Section 6.2 PZT subassembly and Section 7.3 EP30-2 gluing.

We found that the PZTs, which were debonded from the previous PZT sub assy with acetone, has some copper wires oxidized. However, we confirmed that this does not affect the conductivity of the wires, as expected.

The glue test piece cooked in the toaster oven showed excellent curing. GO SIGNAL

Stephen painted the PZT as shown in Attachment 1.

The fixtures were closed with the retaining plate and confirmed that the optics are not moving in the fixtures.

At this point, we checked the situation of the air-bake oven. And we realized that the oven controller was moved to another vacuum oven and in use with a different setting.

Stephen is going to retrieve the controller to the air bake oven and test the temp profile overnight. Once we confirm the setting is correct, the PZT sub assys will be heat cured in the oven.  Hopefully, this will happen tomorrow. Until then, the sub-assys are resting on the south flow bench in the cleanroom.

Attachment 1: IMG_8933.jpg
Attachment 2: IMG_8934.jpg
377   Wed Sep 18 23:38:52 2019 StephenGeneralGeneralDirty ABO ready for PZT Subassembly Bonding

The 40m Bake Lab's Dirty ABO's OMEGA PID controller was borrowed for another oven in the Bake Lab, so I have had to play with the tuning and parameters to recover a suitable bake profile. This bake is pictured below (please excuse the default excel formatting).

I have increased the ramp time, temperature offset, and thermal mass within the oven; after retuning and applying the parameters indicated, the rate of heating/cooling never exceeds .5°C/min.

 Expected parameters: Ramp 2.5 hours Setpoint 1 (soak temperature) 94 °C no additional thermal mass Current parameters: Ramp 4 hours Setpoint 1 (soak temperature) 84 °C Thermal mass added in the form of SSTL spacers (see photo)

The ABO is controlled by a different temperature readout from the data logger used to collect data; the ABO readout is a small bead in contact with the shelf, while the data logger is a lug sandwiched between two stainless steel masses upon the shelf. I take the data logger profile to be more physically similar to the heating experienced by an optic in a gluing fixture, so I feel happy about the results of the above bake.

I plan to add the data source file to this post at my earliest convenience.

Attachment 1: index.png
376   Wed Sep 18 23:16:06 2019 StephenSupplyGeneralItems staged at 40m Bake Lab for PZT Subassembly Bonding

The following items are presently staged at the 40m Bake Lab (see photo indicating current location) (noting items broght by Koji as well):

1. Bonding fixtures, now modified with larger washers to constrain springs, and with modification from OMC elog 358.
2. Curved Mirrors and Tombstones as selected by Shruti in OMC elog 374.
3. PZTs as debonded from first iteration subassemblies (SN 12 and SN 13)
4. Epoxy-cure-testing toaster oven
5. Other items I can't think of but will populate later  =D

The following item is in its home in Downs 303 (Modal Lab)

1. EP30-2 epoxy (expiration 2020 Jan 22) with full kit (tracked in PCS via location update [LINK])

Attachment 1: IMG_5216.JPG
Attachment 2: IMG_5215.JPG
375   Wed Sep 18 22:30:11 2019 StephenSupplyGeneralEP30-2 Location and Status

Here is a summary of the events of the last week, as they relate to EP30-2.

1) I lost the EP30-2 syringes that had been ordered for the OMC, along with the rest of the kit.

• Corrective action: Found in the 40m Bake Lab garbing area.
• Preventative action: log material moves and locations in the OMC elog
• Preventative action: log EP30-2 moves and locations in PCS via location update [LINK]
• Preventative action: keep EP30-2 kit on home shelf in Modal Lab unless kit is in use

2) The EP30-2 syringes ordered for the OMC Unit 4 build from January had already expired, without me noticing.

• Corrective action: Requested LHO ship recently-purchased EP30-2 overnight
• Preventative action: log expiration dates in OMC elog
• Preventative action: begin purchasing program supported by logistics, where 1 syringe is maintained on hand and replaced as it expires

3) LHO shipped expired epoxy on Thursday. Package not opened until Monday.

• Corrective action: Requested LHO ship current EP30-2 overnight, this time with much greater scrutiny (including confirming label indicates not expired)
• Preventative action: Packages should be opened, inspected, and received in ICS or Techmart on day of receipt whenever possible.

4) Current, unopened syringe of EP30-2 has been received from LHO. Expiration date is 22 Jan 2020. Syringe storage has been improved. Kit has been docked at its home in Downs 303 (Modal Lab) (see attached photo, taken before receipt of new epoxy).

Current Status: Epoxy is ready for PZT + CM subassembly bonding on Monday afternoon 23 September.

Attachment 1: IMG_5217.JPG
374   Thu Sep 5 15:40:42 2019 shrutiOpticsConfigurationPZT Sub-Assembly

Aim: To find the combinations of mounting prism+PZT+curved mirror to build two PZT sub-assemblies that best minimises the total vertical beam deviation.

(In short, attachment 1 shows the two chosen sets of components and the configuration according which they must be bonded to minimize the total vertical angular deviation.)

The specfic components and configuration were chosen as follows, closely following Section 2.3.3 of T1500060:

Available components:

Mounting prisms: 1,2,12,14,15 (Even though there is mention of M17 in the attachments, it can not be used because it was chipped earlier.)

PZTs: 12,13

Curved mirrors: 10,13

Method:

For a given choice of prism, PZT and mirror, the PZT can be placed either at 0deg or 180deg, and the mirror can rotated. This allows us to choose an optimal mirror rotation and PZT orientation which minimises the vertical deviation.

Total vertical angle $= \theta_{v, prism} +\theta_{v,wedge} +\theta_{v,mirror}$

$\theta_{v, prism}$ was measured by Koji as described in elog 369.

$\theta_{v, wedge} [\text{arcsec}] = \theta_{PZT} \sin{\frac{\pi \phi_{PZT}}{180}}$,             $\theta_{PZT}, \phi_{PZT}$ are the wedge angle and orientation respectively and were measured earlier and shown in elog 373 .

$\theta_{v, mirror} [\text{arcsec}] = \frac{180 \times 3600 \times d}{\pi R_{RoC}} \times \sin{\frac{\pi (\phi-\phi_{ROT})}{180}}$,               The measurement of the location of the curvature bottom (d, $\phi$) of the mirrors is shown in elog 372 . The optimal $\phi_{ROT}$ is to be found.

These steps were followed:

1. For every combination of prism, PZT, and mirror, the total vertical deviation was minimized with respect to the angle of rotation of the curved mirror computationally (SciPy.optimize.minimize). The results of this computation can be found in Attachment 2: where Tables 1.1 and 2.1 show the minimum achievable deviations for mirrors C10 and C13 respectively, and Tables 1.2 and 2.2 show the corresponding angle of rotation of the mirrors $\phi_{ROT}$ .
2. From the combinations that show low total deviations (highlighted in red in Attachment 2), the tolerances for 5 arcsec and 10 arcsec deviations with mirror rotation were calculated, and is shown in Tables 1.3, 1.4, 2.3, 2.4 of Attachment 2.
3. While calculating the tolerances, the dependence of the vertical deviations with rotation were also plotted (refer Attachment 3).
4. Two sets from available components with low total deviation and high tolerance were chosen.

Result:

These are the ones that were chosen:

1. M14 + PZT13 at 0deg + C13 rotated by 169deg anticlockwise (tot vertical dev ~ -3 arcsec)
2. M12 + PZT12 at 0deg + C10 rotated by 88deg clockwise (tot vertical dev ~0 arcsec)

The method of attaching them is depicted in Attachment 1.

Attachment 1: Diagrams_SubAssembly.pdf
Attachment 2: C10_C13_Combinations.pdf
Attachment 3: Plots_Config_Tolerance.pdf
373   Thu Aug 29 11:51:49 2019 shrutiOpticsCharacterizationWedging of the debonded PZTs - Calculation

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:

Avg. height = 2.0063 mm, 2.0035 mm

Wedge direction (from the same direction as in the doc: positive right) = 120 deg, 120 deg

Wedge angles = 45.8 arcsec, 30.6 arcsec

This was done assuming that the measurements were taken uniformly at intervals of 60deg along the inner rim of the PZT. The diameter (2r) of the inner rim, according to T1500060, is 9mm. The measured heights were fitted with the function

$h = h_0 + \tan(\Omega)\text{ }r(1-\cos(\theta - \alpha))$

as depicted in Attachment2 to find wedging angle $(\Omega)$ and orientation $(\alpha)$.

Quote:

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 while mechanically removing glue. It is also possible that there is systematic error between the two sets of measurements. I did not run any calculations of wedge ange or orientation on these data.

Note that cleaning of debonded PZTs involved mechanically separating glue from the planar faces of PZTs. The second image shows the razer blade used to scrape the glue away.

There were thick rings of glue where there had been excess squeezed out of the bond region, and there was also a difficult-to-remove bond layer that was thinner. I observed the presence of the thin layer by its reflectivity. The thick glue came off in patches, while the thin glue came off with a bit of a powdery appearance. It was hard to be certain that all of the thin bond layer came off, but I made many passes on each of the faces of the 2 PZTs that had been in the bonded CM assemblies. I found it was easiest to remove the glue in the bonded

I was anticipating that the expected 75-90 micron bond layer would affect the micrometer thickness measurements if it was still present, but I did not notice any irregularities (and certainly not at the 10 micron level), indicating that the glue was removed successfully (at least to the ~1 micron level).

 Quote: Yesterday I measured the thickness of the PZTs in order to get an idea how much the PZTs are wedged. For each PZT, the thickness at six points along the ring was measured with a micrometer gauge. The orientation of the PZT was recognized by the wire direction and a black marking to indicate the polarity. A least square fitting of these six points determines the most likely PZT plane. Note that the measured numbers are assumed to be the thickness at the inner rim of the ring as the micrometer can only measure the maximum thickness of a region and the inner rim has the largest effect on the wedge angle. The inner diameter of the ring is 9mm.   The measurements show all PZTs have thickness variation of 3um maximum.  The estimated wedge angles are distributed from 8 to 26 arcsec. The directions of the wedges seem to be random (i.e. not associated with the wires)   As wedging of 30 arcsec causes at most ~0.3mm spot shift of the cavity (easy to remember), the wedging of the PZTs is not critical by itself. Also, this number can be reduced by choosing the PZT orientations based on the estimated wedge directions --- as long as we can believe the measurements.   Next step is to locate the minima of each curved mirror. Do you have any idea how to measure them?

Attachment 1: PZT_Wedging_Results.pdf
Attachment 2: PZT_Wedging_Calc.pdf
372   Fri Aug 23 11:11:44 2019 shrutiOpticsCharacterizationFinding the curvature bottom

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 ($\phi$) from the centre of the mirror. This was done using the method described in a previous similar measurement  and Section 2.1.3 of T1500060.

Initially, I attempted doing a circle_fit on python as seen in Attachment 1, and even though more points seem to coincide with the circle, Koji pointed out that the more appropriate way of doing it would be to fit the following function:

$f(i, \theta, r, \phi) = \delta_{i,0} [r \cos(\theta+\phi) + x_c] + \delta_{i,1} [r \sin(\theta+\phi) +y_c]$

since that would allow us to measure the angle $\phi$ more accurately; $\phi$ is the anti-clockwise measured angle that the curvature bottom makes with the positive x direction.

As seen on the face of the CCD, x is positive up and y is positive right, thus, plotting it as the reflection (ref. Attachment 2) would make sure that $\phi$ is measured anti-clockwise from the positive x direction.

The distance from the curvature bottom is calculated as

$d = \frac{rR}{2L}$

r: radius of precession on CCD screen (value obtained from fit parameters, uncertainty in this taken from the std dev provided by fit function)

R: radius of curvature of the mirror

L: Distance between mirror and CCD

R = 2.575 $\pm$ 0.005 m (taken from testing procedure doc referenced earlier) and L = 0.644 $\pm$ 0.005 m (value taken from testing doc, uncertainty from Koji)

d (mm) $\phi$ (deg)
C7 0.554 $\pm$ 0.004 -80.028 $\pm$ 0.005
C10 0.257 $\pm$ 0.002 -135.55 $\pm$ 0.02
C13 0.161 $\pm$ 0.001 -79.31 $\pm$ 0.06

Attachment 1: CircleFit.pdf
Attachment 2: SineFit.pdf
371   Thu Aug 22 12:35:53 2019 StephenOpticsCharacterizationWedging of the debonded PZTs 2019 August

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 while mechanically removing glue. It is also possible that there is systematic error between the two sets of measurements. I did not run any calculations of wedge ange or orientation on these data.

Note that cleaning of debonded PZTs involved mechanically separating glue from the planar faces of PZTs. The second image shows the razer blade used to scrape the glue away.

There were thick rings of glue where there had been excess squeezed out of the bond region, and there was also a difficult-to-remove bond layer that was thinner. I observed the presence of the thin layer by its reflectivity. The thick glue came off in patches, while the thin glue came off with a bit of a powdery appearance. It was hard to be certain that all of the thin bond layer came off, but I made many passes on each of the faces of the 2 PZTs that had been in the bonded CM assemblies. I found it was easiest to remove the glue in the bonded

I was anticipating that the expected 75-90 micron bond layer would affect the micrometer thickness measurements if it was still present, but I did not notice any irregularities (and certainly not at the 10 micron level), indicating that the glue was removed successfully (at least to the ~1 micron level).

 Quote: Yesterday I measured the thickness of the PZTs in order to get an idea how much the PZTs are wedged. For each PZT, the thickness at six points along the ring was measured with a micrometer gauge. The orientation of the PZT was recognized by the wire direction and a black marking to indicate the polarity. A least square fitting of these six points determines the most likely PZT plane. Note that the measured numbers are assumed to be the thickness at the inner rim of the ring as the micrometer can only measure the maximum thickness of a region and the inner rim has the largest effect on the wedge angle. The inner diameter of the ring is 9mm.   The measurements show all PZTs have thickness variation of 3um maximum.  The estimated wedge angles are distributed from 8 to 26 arcsec. The directions of the wedges seem to be random (i.e. not associated with the wires)   As wedging of 30 arcsec causes at most ~0.3mm spot shift of the cavity (easy to remember), the wedging of the PZTs is not critical by itself. Also, this number can be reduced by choosing the PZT orientations based on the estimated wedge directions --- as long as we can believe the measurements.   Next step is to locate the minima of each curved mirror. Do you have any idea how to measure them?

Attachment 1: IMG_4775.JPG
Attachment 2: IMG_4770.JPG
370   Mon Jul 1 12:49:42 2019 KojiOpticsCharacterizationScattering measurement of A and C mirrors

Liyuan's scattering measurement for the A and C mirrors.

Attachment 1: omc_cm_tis_062419.pdf
Attachment 2: omc_prism_tis_062419.pdf
369   Mon Jul 1 12:38:49 2019 KojiOpticsCharacterizationA and M prisms perpendicularity measurement

[Stephen, Koji]

The perpendicularity of some of the A and M prisms were tested.

Results

- The measurement results are listed as Attachment 1 and 2 together with the comparisons to the measurement in 2013 and the spec provided from the vendor.
- Here, the positive number means that the front side of the prism has larger angle than 90deg for the air side. (i.e. positive number = facing up)
- The RoC of the curved mirrors is 2.5m. Therefore, roughly speaking, 83arcsec corresponds to ~1mm beam spot shift. The requirement is 30 arcsec.
- The A prisms tend to have positive and small angle deviations while the M prisms to have negative and large (~50arcsec) angle deviations.
- The consistency: The measurements in 2013 and 2019 have some descrepancy but not too big. This variation tells us the reliability of the measurements, say +/-30arcsec.

Setup

- The photos of the setup is shown as Attachments 3/4/5. Basically this follows the procedure described in Sec 2.2.2 of T1500060.
- The autocollimator (AC) is held with the V holders + posts.
- The periscope post for the turning Al mirror was brought from Downs by Stephen.
- The turning mirror is a 2" Al mirror. The alignment of the turning mirror was initially aligned using the retroreflection to the AC. Then the pitching of the holder was rotated by 22.5deg so that the AC beam goes down to the prism.
- The prism is held on a Al mirror using the post taken from a prism mount.
- If the maximum illumination (8V) is used, the greenish light becomes visible and the alignment becomes easier.
- There are two reflections 1) The beam which hits the prism first, and then the bottom mirror second, 2) The beam which hits the bottom mirror first and then the prism second. Each beam gains 2 theta compared to the perfect retroreflection case. Therefore the two beams have 4 theta of their relative angle difference. The AC is calibrated to detect 2 theta and tells you theta (1div = 1 arcmin = 60 arcsec). So just read the angle defferencein the AC and divide the number by 2 (not 4).

Attachment 1: A_prism.png
Attachment 2: M_prism.png
Attachment 3: P_20190627_222658.jpg
Attachment 4: setup2.JPG
Attachment 5: M01_1_id.JPG
Attachment 6: A14_meas.JPG
368   Mon Jun 24 12:54:58 2019 KojiCleanGeneralHEPA BOOTH

https://www.airscience.com/purair-flow-laminar-flow-cabinets

367   Tue May 28 12:14:20 2019 StephenOpticsGeneralCM PZT Assembly Debonding of EP30-2 in Acetone

[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 between tombstone-PZT and between PZT-optic. Debonding was straightforward after 8 days of soaking. 24 hours of additional acetone soaking will now be conducted in an attempt to remove remnant EP30-2 from bonding surfaces.

Procedure: The assemblies were allowed to soak in acetone for 8 days, with acetone level below the HR surface of the optic. No agitation of the solution, mechanical abrasion of the bond, or other disturbance was needed for the bond to soften.

GariLynn contributed the glassware and fume hood, and advised on the process (similar to debonding of CM and PZT from OMC SN002 after damaging event). The equipment list was (WIP, more detail / part numbers will be gathered today and tomorrow):

• crystallizing dish (no spout, like a deep petri dish)
• curved lid
• wax sheet (to seal)
• acetone
• fume hood

Results: Today, 28 May 2019, I went to the lab to check on the optics after 8 days of soaking. Liyuan had monitored the acetone level during the first 4 days, topping up once on 24 May. All bonds were fully submerged for 8 days.

There were 2 assemblies soaked in one crystallizing dish. Debonded assemblies - ref OMC eLOG 328 for specified orientations and components:

PZT Assy #9 - ref. OMC eLOG 334 - M17+PZT#12+C10

PZT Assy #7 - ref. OMC eLOG 332 - M1+PZT#13+C13

PZT Assy #7 was investigated first.

• C13 was removed with no force required.
• PZT#13 was removed with no force required.
• EP30-2 remained at the bond surfaces and tracing the diameters of each bond on each of the 3 bonding surfaces of the PZT and tombstone - these components were returned to the dish to soak.
• No EP30-2 remained on the surface of the curved mirror - C13 was removed and stored.

A video of removal of C10 and PZT#12 from PZT Assy #9 was collected (See Attachment 8), showing the ease with which the debonded components could be separated.

• C10 was removed with no force required.
• A slight force - applied by gripping the barrel of the PZT and pushing with the index finger on the surface of the tombstone - was required to separate PZT#12 from M17,
• likely due to excess glue at the barrel of the PZT
• EP30-2 remained at the bond surfaces and tracing the diameters of each bond on each of the 3 bonding surfaces of the PZT and tombstone - these components were returned to the dish to soak.
• No EP30-2 remained on the surface of the curved mirror - C13 was removed and stored.

Photos and video have been be added to supplement this report (edit 2019/07/08).

Attachment 1: omc367_IMG_3499_omc_removal_c13_from_CM7.JPG
Attachment 2: omc367_IMG_3500_omc_removal_pzt13_from_CM7.JPG
Attachment 3: omc367_IMG_3501_omc_removal_pzt13_from_CM7_thickness.JPG
Attachment 4: omc367_IMG_3505_omc_removal_M1_from_CM7.JPG
Attachment 5: omc367_IMG_3507_omc_removal_c10_from_CM9.JPG
Attachment 6: omc367_IMG_3512_omc_removal_pzt12_from_CM9.JPG
Attachment 7: omc367_IMG_3515_omc_removal_m17_from_CM9.JPG
Attachment 8: omc367_IMG_3506_omc_removal_of_c10_and_pzt12_from_CM9.MOV
366   Thu May 23 23:27:38 2019 KojiOpticsCharacterizationIGHQEX3000 high power test

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.

- No significant change of the dark noise after each illumination.

- No visible change of the surface observed.

(During this dark noise measurement, the current amp gain was set to be 1e8 V/A, instead of 1e7 for the measurements yesterday.)

Attachment 1: HQEPD_high_power_test.pdf
Attachment 2: pd_images.png
365   Thu May 23 01:42:46 2019 KojiOpticsCharacterizationC30665 high power test

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.

- No significant change of the dark noise after each illumination.

- No visible change of the surface observed.

Attachment 1: C30665_high_power_test.pdf
Attachment 2: pd_surface.jpg
364   Wed May 22 07:31:37 2019 KojiOpticsConfigurationCamera test (DCPD high power test)

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.

Attachment 1: 20190521201838_IMG_7939_2.jpg
363   Mon May 20 19:53:17 2019 KojiOpticsConfigurationDCPD high power test

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, 30mA of photocurrent with the transimpedance of 400 Ohm is already enough to saturate the circuit. This means that the test is intended to check the damage of the photodiode mainly by the optical power.

The test procedure is as follows:

1. Illuminate the diode with certain optical power.
2. Measure the dark current and dark noise of the PD with no light on it.
3. Check the condition of the PD surface with a digital camera.
4. Repeat 1~3 with larger optical power.

The beam from an NPRO laser is delivered to the photodiode. The maximum power available is 300~400mW. The beam shape was regulated to have the beam radius of ~500um.

- When the PD is exposed to the high power beam, the circuit setup A) is used. This setup is intended to mimic the bias and transimpedance configuration used in the DCPD amp at the site.

- When the dark noise is measured, the circuit setup B) is used. This setup is low noise enough to measure the dark noise (and current) of the PD.

- The test procedure is going to be tested with an Excelitas 3mm InGaAs PD (C30665), and then tested with the high QE PD.

Attachment 1: BIAS.pdf
Attachment 2: P_20190520_204822.jpg
362   Thu May 16 12:41:28 2019 ChubGeneralGeneralfire pillow found on optics table

That is an expanding fire pillow, also known as firebrick.  It is used to create a fire block where holes in fire-rated walls are made and prevents lab fires from spreading rapidly to adjacent labs.  I had to pull cable from B254 to our labs on either side during a rather narrow window of time.  Some of the cable holes are partially blocked, making it difficult to reach the cable to them. The cable is then just guided to the hole from a distance.  With no help, it's not possible to see this material getting shoved out of the hole.  I can assure you that I took great pains not to allow the CYMAC coax to fall into any equipment, or drag against any other cables.

361   Wed May 15 19:07:53 2019 KojiCleanGeneralWhat is this???

Suddenly something dirty emerged in the lab. What is this? It looks like an insulation foam or similar, but is quite degraded and emits a lot of particulates.

This does not belong to the lab. I don't see piping above this area which shows broken insulation or anything. All the pipes in the room are painted white.

The only possibility is that it comes from the hole between the next lab (CRIME Lab). I found that the A.C. today is much stronger and colder than last week. And there is a positive pressure from CRIME Lab. Maybe the foam was pushed out from the hole due to the differential pressure (or any RF cable action).

Attachment 1: P_20190515_185602.jpg
Attachment 2: P_20190515_185844.jpg
360   Thu May 9 18:10:24 2019 KojiOpticsCharacterizationOMC(004): Spot position scan / power budget

(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 that realized the transmission of ~96%. FM1 and FM2 also showed bright spots. The replacement of the FM mirrors does not improve nor degrade the transmission significantly. The transmission is still sensitive to the spot positions on the alignment. This indicates that the loss is likely to be limited by CM1.

Attachment 2 shows the distribution of the (known) scattering spots on CM1. The bright spots are distributed every ~1mm on the spot height and the beam (with beam radius of .5mmm) can't find a place where there is no prominent spots.

We will be able to examine if the transmission can be improved or not by replacing this CM1 mirror.

Attachment 1: 190508.png
Attachment 2: scattering_spots_CM1.png
359   Thu May 9 17:35:07 2019 KojiOpticsGeneralAlignment strategy

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 is not simple.
- 1div of a micrometer is 10um. This corresponds to the angular motion of 0.5mrad (10e-6/20e-3 = 5e-4). ~0.5mm spot motion.
- ~10um displacement of the mirror longitudinal position has infinitesimal effect on the FSR. Just use either micrometer (-x side).
- 1div of micrometer motion is just barely small enough to keep the cavity flashing. => Easier alignment recovery. Larger step causes longer time for the alignment recovery due to the loss of the flashes.

- After micrometer action, the first move should be done by the bottom mirror of the periscope. And this is the correct direction for beam walking.

- If x3 should be moved more than x4, use CM2, and vise versa.
- If you want to move x3 to +x and keep x4 at a certain place, 1) Move CM2 in (+). This moves x3 and x4 but x3>x4. 2) Compensate x4 by turning CM1 in (-). This returnes x4 to the original position (approximately), but leave x3 still moved. Remember the increment is <1div of a micrometer and everytime the cavity alignment is lost, recover it before loosing the flashes.

Attachment 1: T1500060_OMC_Optical_Testing_Procedure.pdf
358   Thu May 9 16:07:18 2019 StephenMechanicsGeneralImprovements to OMC Bonding Fixture

[Stephen, Koji]

As mentioned in eLOG 331, either increased thermal cycling or apparent improvements in cured EP30-2 strength led to fracture of curved mirrors at unintended locations of bonding to the PEEK fixture parts.

The issue and intended resolution is summarized in the attached images (2 different visualizations of the same item).

Redline has been posted to D1600336-v3.

Drawing update will be processed shortly, and parts will be modified to D1600336-v4.

Attachment 1: image_of_issue_with_OMC_PZT_bonding_fixture_from_D16003336-v3.png
Attachment 2: image_02_of_issue_with_OMC_PZT_bonding_fixture_from_D16003336-v3.PNG
357   Fri May 3 11:06:28 2019 KojiOpticsCharacterizationOMC(004): Spot positions and the scattering

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.
FM2 (A14): h=-0.8mm -> 0.2mm reduced the number of spots from 2 to 1. And it is darker. The remaining spot at the center.
CM1 (C11): h=-1.3mm -> +1.0mm made the spot much darker.
CM2 (C12): h=-0.7mm -> +0.2mm remains dark.

Note: CM1 h=1mm and CM2 h~0mm are good locations. h+ is the good direction to move. Avoid h-.
FM1 and FM2 has the scat spots at the center. Want to go h+ more.

Uniformly go h+ is the good move. => This can be done by rotate CM1 positive => CM1 right knob CCW.

 2019/5/1 CM1 right micrometer 1div backward Unit V_RefPD [V] P_TRANS 13.53 [mW] 3.09 V_REFL_LOCKED 53.4 [mV] 3.09 V_REFL_UNLOCK 2.52 [V] 3.065 P_IN 14.45 [mW] 3.07 V_REFL_OFFSET -6.35 [mV] Coupling 0.977 OMC_Trans 0.953

Improvement of the transmission from 93.9%->95.3%

- Further moved CM1 right knob 0.5div (0.5um) backward such that the spots were moved to h+ directions.
FM1 (A5): h=0.4mm -> 1.1mm (there is only one spot rather than multiple spots)
FM2 (A14): h=0.2mm -> 1.1mm (darker but multiple spots)
CM1 (C11): h=1.0mm -> 1.8mm (brighter but single spot)
CM2 (C12): h=0.2mm -> 1.5mm (dark multiple spots)

 2019/5/1 CM1 right micrometer 0.5div backward Unit V_RefPD [V] P_TRANS 14.55 [mW] 3.28 V_REFL_LOCKED 49 [mV] 3.28 V_REFL_UNLOCK 2.755 [V] 3.299 P_IN 15.64 [mW] 3.3 V_REFL_OFFSET -6.316 [mV] Coupling 0.980 OMC_Trans 0.955

Not much improvement of the transmission but kept 95% level.

- Replaced FM1 (A5) with A1 mirror (No photo)

Good news: This did not change the cavity alignment at all.

Transmission 95.4%

- Tweaked the CM1 angle

Transmission 95.3%

=> A1 mirror does not improve the transmission much.

Next Plan: Use A5 (or something else) as FM2 and see if A14 caused the dominant loss.

Attachment 1: misalignment.pdf
356   Wed May 1 15:40:46 2019 KojiOpticsCharacterizationOMC(004): Spot positions and the scattering

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 of the M1 prism (and removed it), I gave it a try again. Resulting spots are again very high. This results in rejecting PZT ASSY #7 and we set the combination of the PZT ASSYs as #8 (M7+P11+C11) and #10 (M21+P22+C12). This combination nominally gives the spot ~1mm above the center of the curved mirrors.

2. Swapped FM1 and FM2. Now FM1=A5 and FM2=A14.

No significant change of the scattering features on the FMs. The transmitted power was 14.85mW (Ref PD Vin = 3.42V), Reflection PD Vrefl,lock = 54.3mV and Vrefl,unlock = 2.89V (Vin=3.45V), Vrefl,offset = -6.39mV. The incident power was 17.43mW (Vin 3.69V).

==> Coupling 0.979 , OMC transmission 0.939 (This includes 0.6% loss to the QPD path) ...Not so great number

3. Built better camera setups to check the spot position and the scattering from the cavity mirrors.

Now the spot heights are fixed and safe to move the camera up for inches to obtain better views of the mirror faces. The camera was set 15" away from the mirrors with 1.5" height from the beam elevation. This is 0.1rad (~ 5 deg) and Cos(0.1)~0.995 so the distortion (compression) of the view is negligible. (Attachment) The spot photo were taken with the fixed CCD gain, the focus on the glass, and  lens aperture F=8.0. Later the focus and aperture were adjusted to have clear view of the scattring points.

The intensity of each scattering was constant at different views. I suppose this is because the scattering is coming from a spot smaller than the wavelength. The bright spots does not show any visible feature on the mirror surfaces when they were inspected with a green flash light.

CM2 has the excellent darkness and we want to keep this spot position. FM1, FM2, and CM1 showed bright scattering.

The spot at CM1 is not well centered on the mirror. And this is the way to avoid this scattering point. So let's think about to move the spot on CM1 by 1.3mm towards the center while the spot on the CM2 is fixed. Note that this is going to be done by the micrometers for CM1 and CM2.

By turning right micrometer of CM1 forward (50um = 5div = 1/10 turn) and the left micrometer of CM2 backward (60um = 6div) moves the spots on FM1, FM2, CM1, and CM2 by (0.43, 0.87, 1.3, 0)mm. This basically moves the spots toward the center of each mirror. Let's give it a try.

Attachment 1: misalignment.pdf
355   Thu Apr 25 15:05:19 2019 JoeOpticsCharacterizationLooking at PZT HOM spacing dependance and thinking about workflow

[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. We took a pzt mirror out and replaced it, the alignment din't change much so that was good. We set up posts to hold the pzt wires.

We noticed that the bottom of the mirrors were dirty, so we cleaned them, and once we were happy with the newton rings, we aligned the cavity

Took a photo of CM2, the spot is maybe 1 beam diameter vertically and horizontally from the centre, and quite a bright spot could be seen. The same problem with CM1. We thought it would be good to see a measurement of higher order mode spacing dependence on PZT DC voltage rather than doing the full characterisation since the alignment seems to change quite a lot when ever we do anything, and this cavity arrangement probably isn't very good anyway (can see scattering on both curved mirrors with the IR camera).

did measurements of FSR, = 2.64835MHz

did HOM spacing for 0,75,150V on CM1 in pitch and yaw.

we want to come up with a work flow for how to do these measurements, and make automate parts of the analysis?

354   Wed Apr 24 13:58:51 2019 JoeOpticsCharacterizationOMC power budget and UV Epoxy Bonding of BS1

[koji,philip,joe,liyuan,stephen]

Mirrors: PZT11,PZT22, A14, A5

 Measurement postion Power P_normalise P_in 15.66+-0.01mV 3.251+-0.001 V_ref,lock 64+-2mV 3.22+-0.001 V_ref,unlock 2.808+-0.001 V 3.253+-0.001 P_qpd 99.5+-0.5 uW 3.24+-0.002 P_cm1 79.0+-0.5 uW 3.22+-0.002 P_cm2 76.2+-0.03 uW 3.22+-0.01 P_trans 14.55+-0.05 mW 3.22+-0.01 Vref,dark -6.286 mV +-0.01mV

Mode matching = 97.72%

15.66-> 15.30mW coupled.

~100uW for QPD

->15.2mW in cavity

Trans = 14.55mW -> 95.7% transmission

The flat mirrors were the ones with the most scattering, so we thought about how to improve it. We tried to move the first flat mirror by pushing it with our finger so that he beam would move along the optic. We tried this a couple of times, however the second time we moved it we lost our alignment and could not retrieve it. We looked at the mirror and we could see quite a lot of newtonian rings. We could see a small fibre on the glass bread board. We cleaned the optics base and the gbb, and we could get the alignment back. The beam was aligned to the cavity, the spots no longer hit the centre of the CM2.

We measured the power budget again.

 Measurement position Power P_normalise V_ref,lock 47mV 3.24V P_trans 14.45+-0.005mW 3.24 +-0.003 V V_ref,unlock 2.68+-0.001 V 3.25+-.003

mode matching = 1-47/2680 = 0.9824, 98.2% mode matching

same p_normalise so

15.66-> 15.34mW coupled.

~15.24mW in cavity

transmission = 14.45, so 94.8% transmission.

Koji noticed that FM1 wasn't touching the template correctly, so he re-aligned the cavity.

Afternoon session - UV Bonding (E1300201-v1 procedure 6.4.4 "Gluing" using procedure in section 7.2 "UV Gluing")

Wiped down UV PPE, UV Illuminator, and UV Power Meter

Applied Optocast 3553-LV Epoxy to sample fused silica optics, to test quantity of glue needed and to become familiar with the process and tools. Philip and Joe each created a successful bond. Joe's had 3 visible spots in the bulk of the bond. Acetone was used to scrub some residue of epoxy from the surface near the OD, which was likely cured. Short duration exposure (seconds) to acetone at the perimeter of the bond did not yield any weakening of bond.

While test pieces were bonded, Koji was making some adjustments to the cavity alignment in preparation for gluing of the steering mirror BS1.

Koji noticed that the spring clamp was causing pitch in the BS1 mirror, so he recommended that we utilize the "restrain by allen key" technique to load the mirror during curing.

Once aligned, we tried taking the BS1 mirror out of the template and then putting it back. We did this twice and both times the cavity needed realigning (with the curved mirrors as well as the input steering periscope). Why is this? Since the mirror was touching the template it should not have become misaligned right? Maybe the template moves slightly? I think before glueing in the cavity mirrors we should find out why probably? Koji took a look and claimed that a few optics may have been unconstrained.

Planning between Koji and Joe led to placement of 5 drops of epoxy on the BS1 surface, to match the bonding area. At this point we noticed that the template was not secured very well, by poking down on it we could see it move. This might explain why we are becoming misaligned very easily. Once the prism was back on the board, Koji used allen keys to move around the prism. This was done until we could align it again (i.t looked too pitched). The beam was aligned back into the cavity, and the UV light was used to cure the bond. The reflected DC when locked was

• pre-cured = 47mV
• cured = 55 mV

so it looks ok still.

353   Tue Apr 23 10:21:12 2019 JoeOpticsConfigurationMoving the spots to the centre of the curved mirrors

[Koji,Philip, Liyuan, Joe]

CM1:

We moved the curved mirrors to these positions:

inner = 0.807mm

outer = 0.983 mm

CM2:

inner = 0.92 mm

outer = 0.85 mm

To do this so that realignment was easier, we moved the screws in steps of 5um. We alternated which mirror we adjusted so that we could monitor with a wincam how well aligned the beam into the cavity was. We only moved the cavity mirrors a small amount so we could still see higher order mode flashes transmitted through the cavity (e.g.TM03 modes). We would then improve the input alignment, and then move the cavity mirrors some more. Once the mirrors were adjusted according to http://nodus.ligo.caltech.edu:8080/OMC_Lab/190422_195450/misalignment4.pdf the spot positions looked near the middle of the curved mirrors (using a beam card). We began beam walking but we ran  out of range of the bottom periscope screws in the yaw dof. We tried using the third screw to move the mirrror in both yaw and pitch, hopefully this will let move the mirror such that we can use the just the yaw screw. This screw also ran out of range, so we decided that the cavity needed a small adjustment.

The curved mirrors were moved slightly (>5um) and then we tried to get alignment. By using the fibre coupler translation stage, we move the beam side ways slightly, and then tried to get the periscope mirrors back to a position where the screws could move the mirrors. Once we had an ok alignment, we checked the beam. It looked like it was pretty close to the centre of the curved mirrors, which is where we wanted it to be.

We then tried locking the cavity, although the error signal was quite small. The adjusted the input offset and gain of the servo (there is apparently some problem to do with the input and output offsets). Once the cavity was locked we could make the final adjustments to aligning. We still ran out of range on the periscope. We decided to move the breadboard with the fibre coupler and mode matching lenses on it. Because we knew that the cavity was aligned such that the beam hits the centres of the curved mirrors, we could regain flashes quite quickly. We saw the error signal go down, but eventually this decrease was just to do with the beam clipping on the periscope mirrors. We moved the spot back to where we ok aligned, and slid the periscope so we were not clipping the mirror. This worked very well, and then optimised the alignment.

We then tried to improve the mode matching.

We took photos of the spot positions (quite near the center) and made the detuned locking measurement. The fitting of the data (attachment 1) wsa 1.1318m (what error should we put here?).

I think the order we did things in was:

• turning anti clockwise on the fibre coupler and misalign the diode, we measured the modespacing.
• returned the alignment for the photodiode, and realign fibre couple.
• miss align the photodiode horizontally, and then used fibre coupler to maximise the peak higher order mode peak height. We then used the PD again to make the peak height bigger.
•
Attachment 1: FSR_detuned_locking.pdf
Attachment 2: CM1_IMG_7702.JPG
Attachment 3: CM2_IMG_7704.JPG
352   Mon Apr 22 19:54:28 2019 KojiGeneral OMC(004): Spot positions at the end of Apr 22nd
Attachment 1: misalignment4.pdf
351   Mon Apr 22 09:54:21 2019 JoeGeneral Shortening cavity (A5,A14,PZT11,PZT22) to get closer to design FSR

[Koji,Joe,Philip,stephen]

in units 20um per div on the micrometer [n.b. we reailised that its 10um per div on the micrometer]

CM1 inner screw pos: 11.5

cm1 outer screw pos: 33.5

cm2 inner screw pos: 11

cm2 outer screw pos: 13

the cavity is currently 3mm too long, move each mirror closer by 0.75mm

CM1 inner screw pos: 11.5+37.5 = 49

cm1 outer screw pos: 33.5+37.5= 71

cm2 inner screw pos: 11+37.5 = 48.5

cm2 outer screw pos: 13+37.5 = 50.5

The screws on the micrometers were adjusted to these values.

cleaned cm1 (PZT 11). There was a mark near the edge which we were not able to remove with acetone. On the breadboard there were 3 spots which we could not remove with acetone. Once we wiped the mirror and breadboard we put the mirror back.

FM2 (A5). The prism looked quite bad when inspected under the green torch, with lots of lines going breadthways. We thought about replacing this with A1, however this has had the most exposure to the environment according to koji. This has a bit of negative pitch, so would bring down the beam slightly. We decided to continue to use A5 as it had worked fairly well before. The breadboard was cleaned, we could see a few spots on it, they were cleaned using acetone.

FM1 (A14). Near the edge of the bottom surface of the prism we could see some shiny marks, which may have been first contact. We attempted to scrape them off we tweezers. The breadboard looked like it had a few marks on it. These were hard to remove with the acetone, it kept leaving residue marks. We used isopropanol to clean this now, which worked much better. The sharp edges of the breadboard can cause the lens tissue to tear a bit, so it took a few rounds of cleaning before it looked good to put a prism on. The mirror was put back onto the breadboard.

The cavity was aligned, then we realised that 1 turn is 500um, so its still too long (1.75mm long). The FSR was 264.433Mhz, which is

CM2 still showed quite a bit more scattering than CM1, so we want to move this beam.

CM1:

• inner = 0.405mm
• outer = 0.67mm

CM2

• inner = 0.507mm
• outer = 0.42mm

want to increase by 1.7/4 = 0.425, so

CM1:

• inner = 0.405+ 0.425 mm = 0.83 mm
• outer = 0.67+ 0.425mm = 1.095 mm

CM2

• inner = 0.507 + 0.425mm = 0.932 mm
• outer = 0.42 + 0.425mm = 0.845 mm

we tried to align the cavity, however the periscope screws ran out of range, so we changed the mircometers on CM2. We tried this for quite some time, but had problems with the beam reflected from the cavity clipping the steering mirror on the breadboard (to close to the outer edge of the mirror). This was fixed by changing the angle of the two curved mirrors. (We should include a diagram to explain this).

The cavity was locke, the FSR was measured using the detuned locking method, and we found that the FSR = 264.805 MHz, which corresponds to a cavity length of 1.1321m

we took some photos, the spot is quite far to the edge of the mirrors (3 to 4mm), but its near the centre vertically. photos are

123-7699 = CM2

123-7697 = CM1

Attachment 1: CM1_IMG_7699.jpg
Attachment 2: CM2_IMG_7697.jpg
350   Sat Apr 20 00:50:12 2019 KojiOpticsCharacterizationOMC(004): Spot positions

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)

Attachment 1: misalignment2.pdf
Attachment 2: misalignment3.pdf
349   Fri Apr 19 11:34:19 2019 KojiOptics OMC initial alignment and locking

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 mirrors.
As for the yaw misalignment, CM1 and CM2 were 3.9mrad and 5.6mrad rotated (misaligned) in CW, respectively.
As for the pitch misalignment, CM1 and CM2 has 1.7mrad (narrowing) and 3.5mrad (widening), respectively. We have no adjustment for this.
Let's say if this comes from the dusts on the bottom of the prisms, CM1 has ~17um one, and CM2 has ~35um one beneath them. The question is if we can believe this or not? This should be checked with the Newton fringes we can see at the bottom of the prisms.

Attachment 1: misalignment1.pdf
348   Fri Apr 19 09:35:28 2019 JoeGeneral Adjusting cavity axis, re-alignment of OMC and locking

[koji,philip, joe, liyuan, steven]

*still need to add photos to post*

PZT 11 was removed and inspected for so dust/dirt on the bottom of the prism. We saw a spot. We tried to remove this with acetone, but it stayed there. (Attachment 2, see the little white spec near the edge of the bottom surface of the prism)

current micrometer positions:

• CM1: one closest to centre 11, close to edge 35 marking
• CM2: both at 20 marking

Swapped PZT for PZT 22, cleaned the bottom and put it into position of CM1. We saw a low number of newton rings, so this is good.

We got a rough initial alignment by walking the beam with the periscope and PZT 22  mirrors. Once we saw a faint amount of transmission, we set up the wincam at the output. The reflected light from the cavity could also be seen to be flashing as the laser frequency was being modulated.

Once it was roughly aligned, using the persicope we walked the beam until we got good 00 flashes. We checked the positions of the spots on the mirror with the beam card. This looked a lot better in the verticle direction (very near the centre) on both curved mirrors. We locked the cavity and contiued to align it better. This was done with the periscope until the DC error signal was about 0.6V. We switched to the fibre coupler after this.

Once we were satisfied that he cavity was near where it would be really well aligned, we took some images of the spot positions. Using these we can work out which way to move the curved mirrors. Koji worked this out and drew some diagrams, we should attach them to this post. [Diagram: See Attachment 1 of ELOG OMC 350]

We made the corrections to the cavity mirrors

• CM1: one closest to centre 11, close to edge 35+16 marking
• CM2: I can't remember exactly, Koji created a diagram which would help explain this step [Diagram: See Attachment 2 of ELOG OMC 350]

The scatter from CM1 looked very small, it was hard to see with a viewer or CCD. We had to turn up the laser power by a factor of 3 to begin to see it, indicating that this is a good mirror.

Once this was done, the spot positions looked uch nearer the centre of each mirror. They look pitched 1mm too high, which might be because of the bottom surfaces of the prisms having a piece of dust on them? For now though it was good enough to try take the detuned locking FSR measurement and RFAM measurement.

To see the higher order mode spacing, we misaligned them incoming beam in pitch and yaw so that the TM10 and TM01 modes were excited. The cavity transmission beam was aligned onto the photodiode such that we could make a transfer function measurement (i.e. shift the beam along the photodiode so that only half of the beam was on it, this maximises the amount of photocurrent).

attachment 1 shows the fitting of the detuned locking method for measuring FSR and cavity length/

I saved this data on my laptop. When I next edit this post (hopefully I will before monday, although I might be too tired from being a tourist in california...) I want to upload plots of the higher order mode spacing.

Attachment 1: FSR_Scan_Fitfsrdata.pdf
Attachment 2: IMG_7679_cropped.jpg
347   Fri Apr 19 09:21:07 2019 PhilipOptics Cleaning of OMC optics

ach[Joe, Phillip, Koji, Stephen]

Work from 17.04.2019

First contact cleaning of OMC optics
We cleaned the OMC optic with first contact. After a first cleaning run all mirrors except for two looked
fine. One had some first contact residuals on the left at center height and another had some particle sitting
near the center area. As the ionized nitrogen gun didn't help we applied another round of first contact which resolved
the two issues. Unfortutanely the second run of cleaning again left some residuals of first contact at the edges.
We were able to peal these off with tweezers.

Placement of Optics at the breadboard
We cleaned the contact surfaces for the bonds using optic wipes and pure isopropanol. The placement wen't well for 3 of the 5 optics (low number of newtonian rings).
One was recleaned and placed on the breadboard again which seemed fine. For the 5th no newtonian rings could be seen (either verry ood or bad) we planed on trying it in the current set-up. Mirrors used can be seen in attachment 3.

Attachment 1: IMG_7877.JPG
Attachment 2: IMG_7883.JPG
Attachment 3: IMG_7884.JPG
346   Thu Apr 18 20:47:54 2019 JoeOptics OMC initial alignment and locking

[Joe, Phillip, Koji, Stephen]

• made initial alignment of the cavity. To do this we used the periscope mirrors to aim the incoming beam at the centre of the first mirror and second (1st curved mirror) mirror. Using the micrometers (initial positions was 0.20mm), we moved the first curved mirror so that it hit the third mirror. We then used a combination of the periscope and first curved mirror movements to start seeing 2 or 3 round trips. micrometer was set to roughly 0.11mm. We then only used  periscope mirrors to align the beam into the cavity.
• We set up a wincam at the transmission of the cavity. This was a useful was of seeing what mode was being transmitted through the cavity. We walked the beam with the periscope mirrors until we saw flashes of the TM00 mode.
• Once the cavity was transmitting TM00 modes, we started to lock it. Once it was locked we looked at the the spot positions of beam on the mirrors. Phillip looked with an IR viewer and could see that the spots were too high on both the curved mirrors
• We set up a CCD to capture an image of this. Two post holders have been left in place for easy movement of the CCD.

General notes about working with this set up. The lens on the CCD can come off quite easily, as you just change how much its screwed on to change the focus. Care should be taken that you don't know the template with this as well, as the camera is quite close to the template (and near the edge of the bench!). Also be mindful of the PZT wires, as they can pull the mirrors out of position.

Attachment 1 shows the position of the spots on the mirrors A14 and PZT11. The spots are about 3mm ish from the centre of the curved mirror in the vertical and horizontal direction.

Attachment 2 sketch of mirror positions.

Attachment 3 shows the postion of the spot on PZT13. The spot is less near the edge than on PZT11, but its still 2mm ish from the centre of the curved mirror in both directions.

To move the beam horizontally we can use the alignment matrix in appendix C of T1500060. However since we don't have control over the pitch of the mirrors, moving the spots down could require us to inspect the glass breadboard/prisms for dust. We suspect that PZT could be the culprit, as we could not see newtonian rings between its base and the glass breadboard. One way to test this idea is just to clean the bottom of the PZT with acetone, and see if that improves the spot position. If we don't have to do any work to realign it, then this was not the issue.

Koji pointed out that the spot in attachment 1 is very near the edge of the optic, so shifting the beam horizontally could also fix the vertical issue.

Attachment 1: IMG_7676.JPG
Attachment 2: IMG_7666.JPG
Attachment 3: IMG_7670.JPG
Attachment 4: IMG_7883.JPG
Attachment 5: IMG_7882.JPG
345   Wed Apr 17 10:30:37 2019 PhilipOpticsGeneralOMC optical set-up day 1

[Joe, Koji, Liyuan, Philip, Stephen]
Work done on 16.04.2019

Finishing assembly of transport box
Assembly worked fine except for the clamping structure to clamp the lid of the transport box to the bottom part.
It seemed that some of the plastic of these clamps became brittle during the baking. The plastic was removed and the
clamps where wiped clean. It appears that the clamps can't be locked as they should. Still the transport box should be fine
as the long screws will mainly clamp the two parts together.

Preparing the transport box to mount the breadboard
The lid of the the transport box was placed upside down and clamped to the table. All peak clamping structures where pulled back as far as possible.

Preparation and cleaning of the breadboard
We unpacked the breadboard and found lots of dust particles on it (most likely from the soft paper cover which was used). We used the ionized nitrogen gun
at 25 psi to get rid of the majority of particles and cross-checked with a bright green flash light before and after blowing. The second stage of cleaning was done
below the clean room tent and included the wiping of all surfaces. The breadboard was then placed into the prepared lid of the transport box and clamped with peak
screws.

Unpacking of the template
The previously cleaned template was unpacked while the last layer of coverage was removed below the cleanroom tent.

All peak screws of the clamping structure of the template where removed. The template was placed onto the breadboard only seperated by peak spacers.
All peak screws have been inserted for horizontal clapming. A calipper was used to measure the distance of each edge of the template to the edge of the
breadboard. For documentation the labeled side of the bradboard (facing away from the persons on the pictures) of the upside down breadboard is defined to
be the south side, continuing clockwise with west, north and east. First rough alignment was done by shifting the template on the breadboard and then the
peak screws where used for fine tuning. The caliper values measured where:
North   C 8.32mm     E 8.52 mm     W 8.41 mm
East     C 8.08 mm
South   C 8.32 mm
West    C 8.02 mm
(E indicating east side position, W indicating west side position and C indicating center position)

344   Wed Apr 17 09:08:47 2019 StephenGeneralGeneralOMC(004): Unwrapping and preparing breadboard

[Stephen, Philip, Koji, Joe]

Breadboard D1200105 SN06 was selected as described in eLOG 338. This log describes unwrapping and preparation of the breadboard.

Relevant procedure section: E1300201 section 6.1.5

Breadboard was unwrapped. No issues observed during unwrapping.

• Attachment 1: packaging of SN06.

Visual inspection showed no issues observed in breadboard - no large scratches, no cracks, no chipping, polished area (1 cm margin) looks good.

• Attachment 2: engraving of SN06.

Initially the breadboard has a large amount of dust and fiber from the paper wrapping. Images were gathered using a green flashlight at grazing incidence (technique typical of optic inspection).

PROCEDURE IMPROVEMENT: Flashlight inspection and Top Gun use should be described (materials, steps) in E1300201.

• Attachment 3: particulate before Top Gun, large face.
• Attachment 4: particulate before Top Gun, small face.

Top gun was used (with medium flow rate) to remove large particulate. Breadboard was placed on Ameristat sheet during this operation.

• Attachment 5: particulate after Top Gun

Next, a clean surface within the cleanroom was protected with Vectra Alpha 10 wipes. The breadboard, with reduced particulate after Top Gun, was then placed inside the cleanroom on top of these wipes. Wiping with IPA Pre-wetted Vectra Alpha 10 wipes proceeded until the particulate levels were acceptable.

Joe and Koji then proceeded with placing the breadboard into the transport fixture.

Attachment 1: IMG_7635_packaging_of_sn06.JPG
Attachment 2: IMG_7637_engraving_of_sn06.JPG
Attachment 3: IMG_7641_particulate_before_top_gun_large_face.JPG
Attachment 4: IMG_7644_particulate_before_top_gun_small_face.JPG
Attachment 5: IMG_7646_particulate_after_top_gun.JPG
343   Tue Apr 16 23:11:43 2019 KojiGeneralGeneralBorrowed items from the other labs

Apr 16, 2019
Borrowed two laser goggles from the 40m. (Returned Apr 29, 2019)
Borrowed small isopropanol glass bottole from CTN.

Apr 19, 2019
Borrowed from the 40m:
- Universal camera mount
- 50mm CCD lens
- zoom CCD lens (Returned Apr 29, 2019)
- Olympus SP-570UZ (Returned Apr 29, 2019)
- Special Olympus USB Cable (Returned Apr 29, 2019)

342   Tue Apr 16 21:16:11 2019 KojiOpticsCharacterizationOMC(004): PZT testing for spare OMC

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: All four PZTs seem to be connected to Teflon coated wires. It needs to be checked if these fulfill the vacuum compatibility requirements.

341   Tue Apr 16 17:24:56 2019 KojiOpticsConfigurationOMC(004): E Mirror selection

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

Attachment 1: E_Mirror_selection.pdf
340   Tue Apr 16 16:52:36 2019 KojiOpticsConfigurationOMC(004): B Mirror selection

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.

The attachment is the excerpt from T1500060 with some highlighting.

Attachment 1: B_Mirror_selection.pdf
339   Tue Apr 16 16:40:26 2019 KojiGeneralConfigurationOMC(004): A Mirror selection

We are going to use A5 and A14 for FM1 and FM2. (The role of these two can be swapped)

The reason for the selection is the better perpendicularity among the available prisms.

A11 has the best perpendicularity among them. However, the T didn't match with the others. The pair of A5 and A14 has a good matching with small compromise of the perpend.

The attachment is the excerpt from T1500060.

Attachment 1: A_Mirror_selection.pdf
338   Tue Apr 16 16:35:09 2019 KojiOpticsConfigurationOMC(004): Glass breadboard selection

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.

Attachment 1: BB_selection.pdf
337   Tue Apr 16 11:36:36 2019 KojiOpticsCharacterizationOMC(004): PZT testing for spare OMC

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)

Attachment 6: The above setting yields 7Vpp unipolar signal @Hi-Z load

Attachment 7: The output was monitored with a 1/10 probe with the PZTs connected. This shows 10Vmax 0Vin -> Good. This photo was taken at 17:35.

Attachment 8: The test is going well @9:15 next day. (t=15.7hours = 5.6Mcycles)

Attachment 9: The test went well. The modulation was stopped @15:35. (t=21hours = 7.6Mcycles)

Attachment 1: IMG_7620.jpg
Attachment 2: IMG_7623.jpg
Attachment 3: IMG_7629.jpg
Attachment 4: IMG_7630.jpg
Attachment 5: IMG_7631.jpg
Attachment 6: IMG_7632.jpg
Attachment 7: IMG_7633.jpg
Attachment 8: P_20190416_091537.jpg
Attachment 9: IMG_7634.JPG
336   Mon Apr 15 21:11:49 2019 PhilipOpticsCharacterizationOMC(004): PZT testing for spare OMC

[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
150 V. The resulting power change then could be converted into a displacement of the PZT using the beam diameter.

The open light value for each of these tests was 3.25 V.

PZT 11:
0 V supply voltage     --> 1.717 V on PD
150 V supply voltage --> 1.709 V on PD
delta = 0.008 V

PZT 12:
0 V supply voltage     --> 1.716 V on PD
150 V supply voltage --> 1.709 V on PD
delta = 0.007 V

PZT 13:
0 V supply voltage     --> 1.702 V on PD
150 V supply voltage --> 1.694 V on PD
delta = 0.008 V

PZT 22:
0 V supply voltage     --> 1.770 V on PD
150 V supply voltage --> 1.762 V on PD
delta = 0.008 V

0.008 V --> 0.24% change in power on PD --> about  3.8 um displacement assuming no light which is blocked
by the PZT is hitting the PD.

We further started to drive all four PZTs over night with 100 V (half of their range) at 100 Hz.

All four PZTs seem to be connected to Teflon coated wires. It needs to be checked if these
fulfill the vacuum compatibility requirements.

335   Mon Apr 15 01:23:45 2019 KojiGeneralGeneralOMC(004): PZT sub-assembly post air-bake inspection (Sub-assy #10)

Sub-ASSY #10

Attachment #1: Mounting Block SN021

Attachment #2: PZT-Mounting Block bonding looks just excellent.

Attachment #3: The other side of the PZT-Mounting Block bonding is also excellent.

Attachment #4: The mirror-PZT bonding also look excellent. Some barrel fracture is visible at the lower left of the mirror.

Attachment 1: IMG_7589.jpg
Attachment 2: IMG_7590.jpg
Attachment 3: IMG_7591.jpg
Attachment 4: IMG_7592.jpg
334   Mon Apr 15 01:07:30 2019 KojiGeneralGeneralOMC(004): PZT sub-assembly post air-bake inspection (Sub-assy #9)

Sub-ASSY #9

The most fractured unit among four.

Attachment #1: Mounting Block SN017

Attachment #2: Two large removals well visbile. The bottom right corener was chipped.

Attachment #3: Another view of the chipping.

Attachment #4: PZT-mounting block bonding look very good.

Attachment #5: Another view of the PZT-mounting block bonding. Looks very good too.

Attachment #6: Fractures bonded on the fixture.

Attachment #7: Front view. The mirror-PZT bonding look just fine.

Attachment 1: IMG_7594.jpg
Attachment 2: IMG_7595.jpg
Attachment 3: IMG_7596.jpg
Attachment 4: IMG_7597.jpg
Attachment 5: IMG_7598.jpg
Attachment 6: IMG_7600.jpg
Attachment 7: IMG_7618.jpg
ELOG V3.1.3-