• Mirror List
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/152
   
• Mirror T measurement:
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/100
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/112
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/114
   
• Curved mirror curvature center test:
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/91
   
• Curved mirror thickness:
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/50
   
• Curved mirror curvature measurement:
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/49
   
• Mirror A/B/E and mounting prism perpendicularity measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/65
   
• Mirror A/B wedge measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/60
   
• Mirror E wedge measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/66
   
• PZT wedge measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/53
   
• PZT actuator response & L2A coupling
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/102
   
• Diode test
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/73
   
• Diode QE measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/78
   
• Breadboard dimension measurement
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/27
   
• Mirror list for L1OMC
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/113
   
• Mirror list for H1OMC
  http://nodus.ligo.caltech.edu:8080/OMC_Lab/151
   

Test result of the PZTs by Valera and Ryan

PZT  Length Angle
 #   [nm/V] [urad/um]
 11  14.5   17.6
 12  13.8   17.8
 13  11.2   25.0
 14  14.5    6.6
 15  12.5   10.6

 21  14.5    9.7
 22  13.8   28.8
 23  14.5    6.8  ==> Assembly #2
 24  18.5   51.7  ==> Used for prototyping
 25  17.1   13.8
 26  14.5    6.6  ==> Assembly #1

Assembly #1:

Mounting Prism #16
PZT #26
Mirror C6

Assembly #2:

Mounting Prism #20
PZT #23
Mirror C5

[Jeff, Zach, Koji]

PZT assembly gluing

Glue gun -> to be returned to MIT
Fixtures x2
Al bases, spacers
spare screws
mirrors / prisms / PZTs
IPA bottle
clean tools x2
first contact kit
gloves (7.5)

Mode matching:

[Koji, Zach]

Tonight, we locked the "fauxMC". We obtained a visibility of >99%.

Koji had aligned it roughly last night, but we wanted to have a couple steering mirrors in the path for this practice cavity (the periscope mirrors will serve this function in the real setup), so we marked the alignment with irises and installed two extra mirrors.

After obtaining flashes with the WinCam placed at the output coupler, we removed the WinCam and put a CCD camera at one of the curved mirror transmissions and used this to get a strong TEM₀₀ flash. Then, we installed the REFL PD/CCD, swept the laser PZT and optimized the alignment by minimizing the REFL dips. Finally, we connected the RF electronics and locked the cavity with the LB box. We used whatever cables we had around to trim the RF phase, and then Koji made some nice SMA cables at the 40m.

One thing we noticed was that we don't have enough actuation range to keep the cavity locked for very long---even with the HV amp (100V). We are going to offload to the NPRO temperature using an SR560 or pomona box circuit. We may also make an enclosure for the cavity to protect it from the HEPA blasting.

Tomorrow, after we do the above things, we will practice measuring the transmission, length (FSR) and mode spectrum of the cavity before moving on to the real McCoy.

[Zach, Jeff, Koji]

- Jeff configured the bottom side template to have a nominal value
obtained from the solid works model. Note that the thickness of the
curved mirrors are 6mm in the model. He added 0.3mmx2 to the dimensions.

- Jeff located the template on the breadboard such that each side has
the same amount of hanging out.

- Micrometer values

• The one closest to the input mirror (CM1) 0.07
• The other one on CM1 0.24
• The one closest to the output mirror (CM2) 0.17
• The other one on CM2 0.30

/------------\

0.17         0.07
\------------/
0.30         0.24

- Now the template is ready to accept the OMC optics.

 

- Zach and Koji finished a series of measurements for the test OMC.

Modulation depth:

- We scanned the laser PZT and recorded the data.
CH1: Reflection DC
CH2: PDH Error
CH3: Transmission (Magnified)
CH4: Transmission

- We should be able to obtain the estimation of the modulation depth and the finesse from this measurement.

- Rough calculation of the modulation depth is 0.19

Transmission:

- Incident 16.3mW
- Transmission 15.1mW
- This gave us the raw transmission of 92.6%ish.
- The modulation depth of 0.19 corresponds to 1.8% of the incident power
- The carrier reflection is almost dominated by the mode mismatch. (Note: We did not have a good resolution for the refl beam)  =>3.2%

- In total:The incident useful carrier power was 15.4mW ==> Throughput 98%
- There is slight headroom to increase the transmission by cleaning the mirrors.

FSR/Finesse:

- As our AOM is not functioning now, phase modulation sidebands are injected with the BBEOM.
- In principle, we can't expect any signal at the transmission at around the FSR frequency.
- If we apply small locking offset, the split peaks appear at the FSR frequency. The frequency of the dip corresponds to the FSR.
- We probably can extract the finesse of the cavity from this measurement. Lisa is working on this.

HOM/Finesse:

- The same PM injection gives us the frequency of the HOMs.
- We found that our EOM can work until ~500MHz.
- We could characterize the cavity resonance structure more than a single FSR.

[Zach Koji]

The first attempt not to touch the curved mirrors did not work. (Not surprising)
The eigenmode is not found on the mirror surface.

We decided to touch the micrometers and immediately found the resonance.
Then the cavity alignment was optimized by the input steering mirrors.

We got the cavity length L and f_TMS/f_FSR (say gamma, = gouy phase / (2 pi) ) as
    L=1.1347 m        (1.132m nominal)
    gamma_V = 0.219176    (0.21879 nominal)
    gamma_H = 0.219418    (0.21939 nominal)

This was already sufficiently good:
- the 9th modes of the carrier is away from the resonance 10-11 times
  of the line width (LW)
- the 13th modes of the lower f2 sideband are 9-10 LW away
But
- the 19th modes of the upper f2 sideband are 1-3 LW away
  This seems to be the most dangerous ones.
and
- The beam spots on the curved mirrors are too marginal

So we decided to shorten the cavity round-trip 2.7mm (= 0.675mm for each micrometer)
and also use the curved mirrors to move the eigenmode toward the center of the curved mirrors.

After the movement the new cavity length was 1.13209 m.
The spot positions on the curved mirrors are ~1mm too close to the outside of the cavity.
So we shortened the outer micrometers by 8um (0.8 div).
This made the spot positions perfect. We took the photos of the spots with a IR sensor card.

The measured cavity geometry is (no data electrically recorded)
    L=1.13207 m        (1.132m nominal, FSR 264.8175MHz)
    gamma_V = 0.218547    (0.21879 nominal, 57.8750MHz)
    gamma_H = 0.219066    (0.21939 nominal, 58.0125MHz)
- the 9th modes of the carrier is 11-13 LW away
- the 13th modes of the lower f2 sideband are 5-8 LW away
- the 19th modes of the upper f2 sideband are 4-8 LW away

The raw transmission is 94.4%. If we subtract the sidebands and
the junk light contribution, the estimated transmission is 97.6%.

Note:
Even if a mirror is touched (i.e. misaligned), we can recover the good alignment by pushing the mirror
onto the fixture. The fixture works pretty well!
 

[Jeff, Zach, Lisa, Koji]

Gluing of the cavity mirrors went very well!!!

Preparation

- Checked if the cavity is still resonating. => Yes.

- Checked the FSR: 264.251MHz => 1.1345m
  2.5mm too long => Move each micrometer by 0.625mm backward

- FSR&TMS (I)
  Aligned the cavity again and checked the FSR: 264.8485MHz => 1.13194m
  TMS(V): 58.0875MHz => gamma_V = 0.219324
  TMS(H): 58.1413MHz => gamma_H = 0.219526
  the 9th modes of the carrier is 9.7-10.4 line width (LW) away from the carrier resonance
  the 13th modes of the lower f2 sideband are 9.2-10.2 LW away
  the 19th modes of the upper f2 sideband are 0.3-1.8 LW away
  We found that this coincidence of the resonance can be corrected by shortening the cavity round-trip by 0.5mm

- Spot positions (I)
  The spots on the curved mirrors were ~1mm too much inside (FM side). In order to translate the cavity axis,
  MM2 and MM4 were pushed by θ
  θ/2.575 = 1mm ==> θ = 2.6 mrad
  The separation of the micrometers are ~20mm
  d/20mm = 2.6mrad ==> d = 52um

  1div of the micrometer corresponds to 10um => 5div = 50um

- Move the micrometers and adjusted the input steering to recover the alignment.

- In any case we were confident to adjust the FSR/TMS/spot positions only with the micrometers

BS1/FM1/FM2 gluing

- Aligned the cavity

- Glued BS1/FM1/FM2 one by one while the cavity resonance was maintained.
  FM2 was slipping as the table is not leveled well and the fixture was not supporting the optic.

- FSR&TMS (II)
  FSR: 264.964875MHz => 1.13144m (Exactly 0.5mm shorter!)
  TMS(V): 58.0225MHz => gamma_V = 0.218982
  TMS(H): 58.1225MHz => gamma_H = 0.219359
  the 9th modes of the carrier is 10.3~11.7 LW away
  the 13th modes of the lower f2 sideband are 7.4~9.3 LW away
  the 19th modes of the upper f2 sideband are 1.5~4.4 LW away

- Spot positions (II)
  Looked OK.

CM2 gluing

- Glued CM2. The mirror was supported from the back with allen keys.

- FSR&TMS (III)
  FSR: 264.9665625MHz => 1.13144m
  TMS(V): 58.1275MHz => gamma_V = 0.219377
  TMS(H): 58.0813MHz => gamma_H = 0.219202
  the 9th modes of the carrier is 10.2~10.9 LW away
  the 13th modes of the lower f2 sideband are 8.5~9.4 LW away
  the 19th modes of the upper f2 sideband are 1.4~2.7 LW away

- Spot positions (III)
  Looked slightly off at CM2. Pushed MM2 by 4um.

CM1 gluing

- Glued CM1.

- FSR&TMS (IV)
  FSR: 264.964875MHz => 1.13144m
  TMS(V): 58.06625MHz => gamma_V = 0.219145
  TMS(H): 58.08625MHz => gamma_H = 0.219220
  the 9th modes of the carrier is 10.8~11.1 LW away
  the 13th modes of the lower f2 sideband are 8.2~8.6 LW away
  the 19th modes of the upper f2 sideband are 2.6~3.2 LW away

- Spot positions (final confirmation)
  Looked OK. 

Final measurement

- After everything was finished, more detailed measurement has been done.

- FSR&TMS (final)
  FSR: 264.963MHz => 1.13145m
  TMS(V): 58.0177MHz => gamma_V = 0.218966
  TMS(H): 58.0857MHz => gamma_H = 0.219221
  the 9th modes of the carrier is 10.8~11.7 LW away
  the 13th modes of the lower f2 sideband are 7.3~8.6 LW away
  the 19th modes of the upper f2 sideband are 2.6~4.5 LW away

Final values for the micrometers

• MM1: The one closest to the input mirror (CM1) 0.78mm
• MM2: The other one on CM1 0.89
• MM3: The one closest to the output mirror (CM2) 0.90
• MM4: The other one on CM2 0.90

/------------\

0.90         0.78
\------------/
0.90         0.89

[Jeff Koji]

- Placed the optics on the PD/QPD path

- Checked the alignment of the beam on the dummy PD/QPD mounts

- There is a bit of (~0.5mm) shift of the spot position from the center. Mainly downward. This is well within a ball park of the PD mounts.

- The PD/QPD path gluing will take place tomorrow.

- Went to the 40m and received the DCPDs from Bob's lab.

- Took six ISC QPDs for the sake of the OMCs.

- They are now in the OMC lab. 

- Measured the B mirror / E mirror R&Ts.

- Found anomalously high loss (3%) for the B mirrors (BSs)

- Went through the all mirrors. Some mirrors (3 or 4) seemed less lossy (<~1%). They will be used for the DCPD BS.

T&Rs of the B mirrors and some of the E mirrors are measured.

I found that these BSs have high loss (1%~3%) . As this loss will impact the performance of the squeezer
we should pick the best ones for the DCPD path. B5, B6, and B12 seems the best ones.

Mirror | P_Incident   P_Trans     P_Refl      | T             R             loss          |
       | [mW]         [mW]        [mW]        |                                           |
-------+--------------------------------------+-------------------------------------------+
B1     | 13.80+/-0.05 7.10+/-0.05 6.30+/-0.05 | 0.514+/-0.004 0.457+/-0.004 0.029+/-0.005 |
B2     | 14.10+/-0.05 6.50+/-0.05 7.15+/-0.05 | 0.461+/-0.004 0.507+/-0.004 0.032+/-0.005 |
B3     | 13.87+/-0.05 7.05+/-0.05 6.55+/-0.05 | 0.508+/-0.004 0.472+/-0.004 0.019+/-0.005 |
B4     | 13.85+/-0.05 6.78+/-0.05 6.70+/-0.05 | 0.490+/-0.004 0.484+/-0.004 0.027+/-0.005 |
B5     | 13.65+/-0.05 6.93+/-0.05 6.67+/-0.05 | 0.508+/-0.004 0.489+/-0.004 0.004+/-0.005 |
B6     | 13.75+/-0.05 6.70+/-0.05 6.92+/-0.05 | 0.487+/-0.004 0.503+/-0.004 0.009+/-0.005 |
B7     | 13.83+/-0.05 7.00+/-0.05 6.60+/-0.05 | 0.506+/-0.004 0.477+/-0.004 0.017+/-0.005 |
B8     | 13.90+/-0.05 6.95+/-0.05 6.68+/-0.05 | 0.500+/-0.004 0.481+/-0.004 0.019+/-0.005 |
B9     | 13.84+/-0.05 6.95+/-0.05 6.70+/-0.05 | 0.502+/-0.004 0.484+/-0.004 0.014+/-0.005 |
B10    | 13.97+/-0.05 6.98+/-0.05 6.72+/-0.05 | 0.500+/-0.004 0.481+/-0.004 0.019+/-0.005 |
B11    | 13.90+/-0.05 7.05+/-0.05 6.70+/-0.05 | 0.507+/-0.004 0.482+/-0.004 0.011+/-0.005 |
B12    | 13.90+/-0.05 6.98+/-0.05 6.78+/-0.05 | 0.502+/-0.004 0.488+/-0.004 0.010+/-0.005 |
-------+--------------------------------------+-------------------------------------------+

Mirror | P_Incident   P_Trans         P_Refl       | T            R             loss          |
       | [mW]         [uW]            [mW]         | [ppm]                                    |
-------+-------------------------------------------+------------------------------------------+
E4     | 13.65+/-0.05 0.0915+/-0.0005 13.50+/-0.05 | 6703+/-44ppm 0.989+/-0.005 0.004+/-0.005 |
E12    | 13.75+/-0.05 0.0978+/-0.0005 13.65+/-0.05 | 7113+/-45    0.993+/-0.005 0.000+/-0.005 |
E16    | 13.90+/-0.05 0.0975+/-0.0005 13.30+/-0.05 | 7014+/-44    0.957+/-0.005 0.036+/-0.005 |
-------+-------------------------------------------+------------------------------------------+

L1 OMC

Cavity Mirrors

FM1 (input coupler): A8
FM2 (output coupler): A7
CM1 (curved mirror close to FM1): C6
CM2 (curved mirror close to FM2): C5

DCPD path

BS3 (BS for DCPDs): B5 B7

QPD path

BS1 (input steering): E10
SM1 (steering mirror next to BS1): E12
BS2 (BS for QPD path): B3
SM2 (steering mirror next to BS2): E4
SM3 (steering mirror next to SM2): E16

Since the previous measurement showed too high loss, the optical setup was checked.
It seemed that a PBS right before the T&R measurement setup was creating a lot of scattering (halo) visible with a sensor card.

This PBS was placed to confirm the output polarization from the fiber, so it was ok to remove it.

After the removal, the R&T measurement was redone.
This time the loss distributed from 0.2% to 0.8% except for the one with 1.3%. Basically 0.25% is the quantization unit due to the lack of resolution.

At least B7, B10, B12 seems the good candidate for the DCPD BS.

The AR reflection was also measured. There was a strong halo from the main reflection with an iris and sense the power at ~.5mm distance to separate the AR reflection from anything else. Now they are all somewhat realistic. I'll elog the measurement tonight.

33.6 +/- 0.2 uW out of 39.10+/-0.05 mW was observed. The offset was -0.236uW.
This gives us the AR reflectivity of 865+/-5ppm . This meets the spec R<0.1%

Mirror | P_Incident   P_Trans      P_Refl       | T             R             loss          |
       | [mW]         [mW]         [mW]         |                                           |
---------------------------------------------------------------------------------------------
B1     | 39.10+/-0.05 19.65+/-0.05 19.25+/-0.05 | 0.503+/-0.001 0.492+/-0.001 0.005+/-0.002 |
B2     | 39.80+/-0.05 19.90+/-0.05 19.70+/-0.05 | 0.500+/-0.001 0.495+/-0.001 0.005+/-0.002 |
B4     | 39.50+/-0.05 19.70+/-0.05 19.30+/-0.05 | 0.499+/-0.001 0.489+/-0.001 0.013+/-0.002 |
B5     | 39.50+/-0.05 19.70+/-0.05 19.50+/-0.05 | 0.499+/-0.001 0.494+/-0.001 0.008+/-0.002 |
B6     | 39.55+/-0.05 19.50+/-0.05 19.95+/-0.05 | 0.493+/-0.001 0.504+/-0.001 0.003+/-0.002 |
B7     | 40.10+/-0.05 19.80+/-0.05 20.20+/-0.05 | 0.494+/-0.001 0.504+/-0.001 0.002+/-0.002 |
B8     | 40.15+/-0.05 19.80+/-0.05 20.20+/-0.05 | 0.493+/-0.001 0.503+/-0.001 0.004+/-0.002 |
B9     | 40.10+/-0.05 19.90+/-0.05 19.90+/-0.05 | 0.496+/-0.001 0.496+/-0.001 0.008+/-0.002 |
B10    | 40.10+/-0.05 19.70+/-0.05 20.30+/-0.05 | 0.491+/-0.001 0.506+/-0.001 0.002+/-0.002 |
B11    | 40.20+/-0.05 19.80+/-0.05 20.20+/-0.05 | 0.493+/-0.001 0.502+/-0.001 0.005+/-0.002 |
B12    | 40.20+/-0.05 19.90+/-0.05 20.20+/-0.05 | 0.495+/-0.001 0.502+/-0.001 0.002+/-0.002 |
---------------------------------------------------------------------------------------------

Yesterday, all of the glass components for the QPD path were glued.

- Check the alignment of the beam with the cavity.

- Placed the prisms

- Placed the QPD mount for the gluing test. An alignment disk instead of a diode was placed on the mount.

- Checked the spot positions at the QPDs. A CCD camera with a lens was used to find the spot.
  The spots were ~0.5mm lower on the QPD1, and ~1mm lower on the QPD2.

- Glued the first steering mirror while the spot position was continuously monitored.

- Glued the BS in the QPD path while the spot position was monitored.

- FInally a glass bracket was glued.

- The spot on QPD2 was too low to absorb by the QPD shim.

- Once the steering mirror was clamped by a cantilever spring (to prevent slipping), the spot moved up a bit.
  (Or, we should say, the cantilever misaligned the optics a bit in pitch in a preferrable direction.)

- The other steering mirror is clamped by a cantilever spring (to prevent slipping), the spot moved up a bit.
  Or, we should say, the cantilever misaligned the optics a bit in pitch in a preferrable direction.)

- The last steering mirrors was also glued in a same way. As a result the spot is 0.5mm below the center of the alignment disk.

- Once the PD mounting brackets were glued, we can't place the QPD mount on it as the PEEK bar can't be inserted without moving the gluing template.

- The QPD mount with out the glass bracket was used to check the alignment of the beam dumps.
  As the beam dumps have a wide aperture and the yaw alignment of the QPD is big, we could accommodate the beams in the dumps easily.

- The dumps were glued.

[Jeff, Koji]

- While we were working on the optics alignment, one of the mounting brackets made of glass god tore apart into two when a holding screw was removed.
The glass component had a crack at the very middle of the part.

- We borrowed a setup for photoelastisity measurement from Garilynn. This is a set of polarizer configured to have cross polarization. If there is no photoerastisity
the image is colored in blue (somehow). When the polarization is rotated, the color is changed in red, yellow, or white.

- The cross polarizer was tested with a polycarbonate face shield for the UV protection. It seems doing its job.

- We took a set of photos to see any residual stress in a block. The entire inside of the channel is frosted glass so the technique didn't yield much.
In one orientation we did see stress near the ends but the orientation didn't allow us to see exactly where.

- We had 30 brackets and one OMC requires ten of them. This means that there was no spare and now we don't have enough.
  So we decided to spend more as test pieces.

- We tested three scenarios this afternoon. In all three cases both screws were snugged (estimate 0.5 in*lb) before torquing by a torque wrench with a dial meter.
  The divisions on the dial of the wrench are 1 in*lb. We were not so confident in the exact measurement but we felt good about the repeatability of the values.

  1. Duplicated the original mounting with the chamfers of the PEEK bar facing into the channel. Cracked as the torque wrench read 1 in*lb.
      Crack initiation at the first screw, starting along the longitudinal centerline.

  2. Turned the nut bar over so the flat side faced into the channel. Successfully torqued both screws to 1 in*lb and removed them.

  3. With a razor blade, made fairly large reliefs (countersinks) around the holes in the PEEK. Successfully torqued both screws first to 1 in*lb then 1.5 in*lb.
      The block did crack (again at the screw along the centerline) when the torque was ~1.9 in*lb.

It occurs to us that we need micro-compliance AND structural rigidity to distribute the load. The PEEK bars are small and particularly thin where the #4-40 helicoil holes are.
The load is probably concentrated way too much at the holes because it is too weak. Perhaps a good solution, among others, would be to use an aluminum nut plate
with a thin (.02") kapton or viton layer to give the micro-compliance. Additionally, a kapton layer could be used between the block and the aluminum shim,
though this one is probably to be avoided so as to ensure rigidity of the bolted assembly to the bench. Lastly, the nut bar should be shaped such that the area
around the holes and the end of the channel (pretty much the same area) are less stressed than the center portion. 

After the discussion with Peter and Dennis, we decided to reinforce the bonded glass piece with invar shims.
Each shim will be threaded such that we don't need to stress the glass piece any more. EP30-2 will be used as the glue.

[Jeff, Koji]

DCPD path gluing

Usual preparation

- Locked the cavity.

- Aligned the input beam to the cavity

DCPD BS gluing

- Placed the DCPD BS on the breadboard

- Placed the dummy DCPD mount on the reflection side of the BS. Check the height and position of the spot.

- Placed the dummy DCPD mount on the transmission side of the BS. Check the height and position of the spot.

- The spot positions looked fine.

- Added a dub of UV glue on the BS. Placed it along the fixture.

- Checked the reflection spot again with the CCD. Kept monitored the spot position through out the gluing process
of the BS.

- Blasted the UV illumination

Reflection side beam dump gluing

- Replaced the alignment disk of the dummy DCPD with a photodiode with the cap removed.

- Put the dummy DCPD mount and the beam dump in place

- Checked the reflection spot from the diode on the beam dump. It looked fine.

- Applied 2~3 dubs of the glue on the beam dump. Slid in the dump to the fixture.

- Applied UV illumination. As the beam dump shadows the illumination 3 times of 10sec blasts were applied.

Transmission side beam dump gluing

- Put the dummy DCPD mount with the diode in place

- Put the beam dump in place. The template needed to be lifted up a bit to accomplish this action.
This should be fixed by the modification of the template.

- Checked the transmission spot on the diode and the spot reflected from the diode on the beam dump.

- Actually the spot was too much close to the vertex of the "V" on the beam dump. We determined that
this was mainly caused by the misalignment of the diode element, and can be compensated by the tilt of the diode mount.

- Removed the beam dump from the template once. Applied 2~3 dubs of the glue on the beam dump.
Slid in the dump to the fixture by lifting up the template again.

- Applied UV illumination. As the beam dump shadows the illumination 3 times of 10sec blasts were applied.

Mounting bracket gluing

- Glued the mounting brackets for the DCPD mounts based on the positions specified by the template.

Removing the templates

- Removed the connection bars between the two templates.

- Removed the template at the QPD side. The screws at all of the three sides were needed to be released in order to accomplish this action.
Once the screws are released, the template was slid on the breadboard so that the pads did not scratch the optical surface.
Keep one side of the template use as a pivot, lifted up another side until the pads clear the optic. Then lifted up the other side.

- Removed the other template. This time, the screws at the two DCPD sides are released. The template was slid and lifted in a same way.

Last beam dump gluing

- Once the QPD side template was removed, the last beam dump at the transmission side of the first steering mirror was glued.

- This has been done without any gluing fixture, we held the beam dump with clean Allen keys on the breadboard.

- The paths for the main and stray beams were confirmed by an IR sensor card, and blasted the UV.

Closing the transport fixture

- Removed the constraining pins for the breadboard.

- Made sure all of the constraining pins/screws are released for the other side of the transport fixture were released.

- Put the lid on.

- Fastened the constraining pins/screws of the transport fixture.

- Wrapped the fixture with sheets of the Al foil.

- Pack the fixture in anti-static bags.

L1 OMC is back on the table for the action next week.

Measurement Order: DCPD2->DCPD1->QPD1->QPD2

DCPD1: 1.50mm+0.085mm => Beam 0.027mm too low

DCPD2: 1.75mm+0.085mm => Beam 0.051mm too high (...less confident)

QPD1:   1.25mm+0.085mm => Beam 0.077mm too low

QPD2:   1.25mm+0.085mm => Beam 0.134mm too low
          or 1.00mm+0.085mm => Beam 0.116mm too high

Remeasured the spot positions:

DCPD1: 1.50mm+0.085mm => Beam 0.084mm too high

DCPD2: 1.50mm+0.085mm => Beam 0.023mm too high

QPD1:   1.25mm+0.085mm => Beam 0.001mm too low

QPD2:   1.25mm+0.085mm => Beam 0.155mm too low
 

May
(done) Mon  6th: Invar plate arrival / Spot position measurement
(done) Tue  7th: Invar plate cleaning / Spot position measurement / EP30-2 arrival / Invar plate gluing to the test mounting brackets
(done) Wed  8th: Invar plate cleaning done / Baking of the test pieces (with Bob's oven)
Thu  9th: ***After bake torque/force test***

***If the invar plate passes the test***
Thu  9th Light side invar plate gluing
Fri 10th Cable side invar plate gluing

Mon 13th The OMC given to Bob (Air bake & Vac bake)

Mon 20th The OMC received from Bob
         Apply First contact
         Diode mount adjustment / Electronic tests
Tue 21st Diode mount adjustment / Electronic tests / Optical tests
Wed 22nd Final cabling (***Chub***)
Thu 23rd Final cabling / Packing
Fri 24th Packing / Shipping

Mon 27th? Arrival to LLO / Koji fly to LLO
Tue 28th Test on the optical bench
Wed 29th Test on the optical bench
Thu 30th Suspension test? (***Jeff B***)

June
Tue  4th Suspension test done?

[Koji / Jeff]

This is the elog about the work on May 9th.

We made two glass brackets glue on the junk 2" mirrors with the UV glue a while ago when we used the UV bonding last time.

On May 7th:

We applied EP30-2 to the glass brackets and glued invar shims on them. These test pieces were left untouched for the night
and brought to Bob for heat curing at 94degC for two hours.

On May 9th:

We received the test pieces from Bob.

First, a DCPD mount was attached on one of the test pieces. The fasteners were screwed at the torque of 4 inch lb.
It looked very sturdy and Jeff applied lateral force to break it. It got broken at once side of the bracket.

We also attached the DCPD mount to the other piece. This time we heard cracking sound at 2 inch lb.
We found that the bracket got cracked at around the holes. As the glass is not directly stressed by the screws
we don't understand the mechanism of the failure.

After talking to PeterF and Dennis, we decided to continue to follow the original plan: glue the invar shims to the brackets.

We need to limit the fastening torque to 2 inch lb.

The invar reinforcement shims were glued on the glass brackets on the breadboard.
We worked on the light side on May 10th and did on the dark side on May 13rd.

U-shaped holding pieces are used to prevent each invar shim to be slipped from the right place.

We are going to bring the OMC breadboard to the bake oven tomorrow to cure the epoxies and promote the outgasing.

May
Tue 14th The OMC given to Bob (Air bake & Vac bake)

Mon 20th The OMC received from Bob
         Apply First contact
         Diode mount adjustment / Electronic tests
Tue 21st Diode mount adjustment / Electronic tests / Optical tests
Wed 22nd Final cabling (***Chub***)
Thu 23rd Final cabling / Packing
Fri 24th Packing / Shipping

Mon 27th? Arrival to LLO / Koji fly to LLO
Tue 28th Test on the optical bench
Wed 29th Test on the optical bench
Thu 30th Suspension test? (***Jeff B***)

June
Tue  4th Suspension test done?

The OMC is in the air bake oven now.

The OMC came back to the table again.

No obvious change is visible: no crack, no delamination

The OMC was fixed on the table and the beam was aligned to the cavity

- The wrong Mighty Mouse connectors for the PZT wires were prepared. The correct ones are in the vacuum oven till Tuesday morning.

- The thread holes for the cable pegs are 1/4-20 rather than 10-24.  This requires re-machining of the cable pegs & the C&B.

- We are waiting for the fast shipment of the from LHO

May
Thu 23rd Diode mount adjustment / Optical tests
Fri 24th Optical tests
Tue 28th Mighty mouse connector available / Diode mounting finalization
Wed 29th final check
Thu 30th shipment
Fri 31th

June
Mon  3rd ? Arrival to LLO / Koji fly to LLO
Tue  4th Suspension test done?

DCPD mounts and QPD mounts were attached on the breadboard. They are not aligned yet and loosely fastened.

DCPD (mounting 4-40x5/16 BHCS Qty4)

Face plates fatsened by 4-40x5/16 BHCS (24 out of 40)

Housing   Face plate Destination  PD
002       002        L1OMC DCPD1  #10
003       003        L1OMC DCPD2  #11
004       004        H1OMC DCPD1
008       005        H1OMC DCPD2
009       006        I1OMC DCPD1
010       007        I1OMC DCPD2


QPD (mounting 4-40x5/16 BHCS Qty4)

Face plates fatsened by 4-40x1/4 BHCS (24 out of 80)

Housing   Face plate Destination QPD
002       002        L1OMC QPD1  #38 #43 swapped on 29th May.
003       003        L1OMC QPD2  #43 #38 swapped on 29th May.
004       004        H1OMC QPD1
005       005        H1OMC QPD2
006       006        I1OMC QPD1
007       007        I1OMC QPD2

* 4-40x5/16 BHCS Qty 8 left
* 4-40x5/16 BHCS Qty 56 left

Cut the diode legs by 3mm

Yesterday Jeff and Chub worked on the cabling of the OMC. It turned out that the gender of the cable connectors
going from the cavity side to the connector bracket on top of the OMC were opposite from what is needed. 
This way, the connectors can't fixed on the cable harness, thus they are free during the shipping.

We considered several ideas to mitigate this issue and decided to swap the gender of the Mighty Mouse connectors.

In order to check this operation may cause the shortage of the cable length, we made the fitting of the cables.
They seem all long enough for Chub to replace the Mighty Mouse connectors with the proper gender. 

We also checked the polarity of the PZT wires. We marked the positive side of the PZT by a knot at the wire end.

The QPD alignment was adjusted using the aligned beam to the cavity and the 4ch transimpedance amplifier.

As I have a test cable for the QPD, I attached a DB9 connector on it so that I can use the QPD transimpedance
amplifier to read the photocurrent. The transimpedance of the circuit is 1kV/A.
As this board (D1001974) does not have X/Y/SUM output, I quickly made the summing circuit on a universal
board I took from Japan a while ago.

The spot on the QPD1 (shorter arm side) seems too low by ~0.64mm. It seems that the QPD is linearly responding
to the input misalignment, so there is no optical or electrical problem.

As I wonder how much I can improve the situation by replacing the diodes, I swapped the diodes between QPD1 and QPD2.
Now QPD1 and QPD2 have the diode #43 and #38, respectively. It improved the situation a llitle (about 60um).
But the beam is still 0.58mm too low. 95% of the power is on the upper two elements.
Of course this is at the edge of the linear range.
I confirmed we still can observe the cavity is fringing even with the beam is aligned on this QPD. So this may be
sufficient for the initial alignment.

The QPD2 was in a better situation. The spot is about 100um too low but this is still well with in the linear range.

The incident powers on the diodes were also measured. The estimated responsivities and Q.E.s are listed below.
The reflection from the diode is adjusted to hit the beam dump properly.

Here are the raw numbers

QPD#            QPD1       QPD2
Diode#          #43        #38
-------------------------------------
Power Incident  118.8 uW   115.7uW
Sum Out          78.8 mV   84.6 mV
Vertical Out     69.1 mV   11.9 mV
Horizontal Out    9.8 mV   -1.6 mV
SEG1             -1.90 mV -17.8 mV
SEG2             -2.18 mV -17.5 mV
SEG3            -32.0 mV  -25.3 mV
SEG4            -42.0 mV  -23.8 mV
-------------------------------------
Responsivity[A/W] 0.66      0.73
Q.E.              0.77      0.85
-------------------------------------

Arrangement of the segments
View from the beam
/ 2 | 1 X
|---+---|
\ 3 | 4 /

Peter F suggested to check the bottom surface of the PD housings if there is any protrusion/interference/whatever.
And that was true! It was found that the front side of QPD1 (Left) was lifted by a machining burr.
It seems that this burr consistently exists as the other one also have it (see QPD2 picture (right)) although it is not too terrible compared to the one in QPD1.

Once these burrs were removed, the spots were found on the right position of each diode.
From the measurement of the power on each segment, the positions of the spots were estimated. (listed in the table)
They indicate that the spots are within 0.1mm from the center. This is good enough.

The quantum efficiency was measured from the incident power and the sum output. It seems that there are
some difference between the diodes. The numbers are consistent with the measurement the other day.

QPD#              QPD1       QPD2
Diode#            #43        #38
-------------------------------------
Power Incident     84.7 uW   86.2 uW
Sum Out            56   mV   61   mV
Vertical Out       -6.8 mV   10   mV
Horizontal Out      4.2 mV    8.8 mV
SEG1              -17   mV  -15   mV
SEG2              -14.5 mV  -11   mV
SEG3              -11   mV  -15   mV
SEG4              -13   mV  -20   mV
-------------------------------------
Spot position X   +25   um  +46   um  (positive = more power on SEG1 and SEG4)
Spot position Y   -42   um  +46   um  (positive = more power on SEG3 and SEG4)
-------------------------------------
Responsivity[A/W] 0.66      0.71
Q.E.              0.77      0.82
-------------------------------------

Arrangement of the segments
View from the beam
/ 2 | 1 X
|---+---|
\ 3 | 4 /

---------------

I(w,x,y) = Exp[-2 (x^2 + y^2)/w^2]/(Pi w^2/2)

(SEG_A+SEG_B-SEG_C-SEG_D)/(SEG_A+SEG_B+SEG_C+SEG_D) = Erf[sqrt(2) d/w]

d: distance of the spot from the center
w: beam width

Measurement for pitch

The followings are the previous values before the bake
[from this entry]

- After everything was finished, more detailed measurement has been done.

- FSR&TMS (final)
  FSR: 264.963MHz => 1.13145m
  TMS(V): 58.0177MHz => gamma_V = 0.218966
  TMS(H): 58.0857MHz => gamma_H = 0.219221
  the 9th modes of the carrier is 10.8~11.7 LW away
  the 13th modes of the lower f2 sideband are 7.3~8.6 LW away
  the 19th modes of the upper f2 sideband are 2.6~4.5 LW away

- QPD mount aligned, QPD output checked
  The spots are with 100um from the center of the diodes. [ELOG Entry (2nd photo)]

- TMS/FSR dependence on the PZT V
  Shows significant dependence on the PZT voltages
  It seems that the curvartures get longer when the voltages are applied to the PZTs.
  The effect on these two PZTs are very similar. The dependence is something like
  (TMS/FSR) ~ 0.219 - 1e-5 V
  May cause resonance of the higher-order modes (like 13th order of the 45MHz sidebands) at a specific range of the PZTs.
  We can't change anything any more, but the impact needs to be assessed

- DC response of the PZTs [ELOG Entry]
  PZT voltages were swept. Observed multiple fringes during the sweep.
  The data to be analyzed.

- AC response of the PZTs [ELOG Entry]
  PZT1 and PZT2 well matched. The first resonance at 10kHz.

- Open loop TF of the servo
  The UGF more than ~30kHz.

- Cleaning of the main optics with First Contact
  Done. Visible scattering seen with an IR was reduced, but still exist.
  All four cavity mirrors have about the same level of scattering.
  Each scattering is a group of large or small bright spots.
  It's actually a bit difficult to resolve the bright spots with the IR viewer.

- Raw transmission: i.e. Ratio between the sum of the DCPD paths and the incident power
  May 8th (before the baking):      0.918
  May 8th (First Contact applied): 0.940 (improved)
  Jun 2nd (after the baking):         0.927 (worse)
  Jun 2nd (First Cotact applied):   0.964 (improved)

- TMS/FSR/Finesse change before/after cleaning [ELOG Entry]
  Just a small change from the parameters before the bake.
  No quantitative difference.

  Method:
  BB EOM produces the AM sidebands together with the PM sidebands.
  Ideally, the PM sidebands does not produce the signal at the transmission, the output is dominated by the AM component.
  This is only true when there is no lock offset. In reality the curve is contaminated by the PM-AM conversion by the
  static offset or dynamic deviation of the locking point. So I had to take the central part of the TF and check the
  dependence of the fit region and the finesse.

  Before the cleaning: Finesse 396.9
  After the cleaning: Finesse 403.8

To Do

- Placement of the DCPD housings
- Through-put test with DCPDs
- Transmission dependence on the incident power
  (although the max incident is limited to ~35mW)

- Application of the first contact for the surface protection

Monday - Evening
(Koji)
[done] - DCPD alignment
[done] - DCPD test & through-put measurement
[done] - Power dependence test
[done] - Apply Protective First Contact Layer on the optic surfaces
[done] - Wiping the OMC

Tuesday - Morning
(Chub)
[done] - Bring the cable from the oven

Tuesday - Afternoon
(Chub/Jeff)
[done] - Cabling of the OMC

Wednesday - Morning
(Jeff/Koji)
[done] - Cable tying down
[done] - Screw tightening for the PDs
[done] - Wrapping / Packing
[done] - Weighting? (65lb for everything)

(Jeff/George)
[done] - Shipping? (or Wednesday)

Items to be shipped together
v - OMC cables between the cable harness to the suspension
v - 1 PZT cable pin
v - DCPD preamp kit
v - toruqe driver & bits
v - kapton sheet/tube
v - Test PD cables
v - Spare diodes
v - QPD amp circuits (just in case)
v - 1GHz PD / Power supply banana-PD cable / 1GHz PD cables

[done] - Installation scheduling with Peter/Brian/(Mike?)
- Travel plan
[done] Koji goes LLO immediately (possible?) 6/6-6/22
  Jeff goes LLO next week?

(Koji)
[done] - Room cleaning

--------------------------
Optical testing plan

Day 0
- Freight and Koji moving

Day 1 Arrival (Thursday or Friday)
- Inspect the shock detector
- Unpacking
- Check the condition of the breadboard
- Place the transportation fixture on the table
- Removing the First Contact layers
- Locking
- Mode matching

Day 2
- Transmission measurement
- Power dependence test
- PD installation / (diode can opening, optional)
- (PD realign, optional)
- diode test

Day 3
- Power dependence test

---------------------------
OMC installation plan

TBD

---------------------------
OMCS installation plan

TBD

---------------------------
Documents

- OMC Hazard analysis (done)
- OMCS Hazard analysis (done)
- OMC instllation procedure
- OMCS instllation procedure
- Work permits

cf. previous documents: E080024, E1300201

---------------------------

---------------------------
Misc
- LIGO access card
controls@lloisc0-work:~$ 2.23-5mW T
2.23-5mW: command not found
controls@lloisc0-work:~$ 2.17 \pm 0.01 R
2.17: command not found
controls@lloisc0-work:~$ 67-68mV inlock
67-68mV: command not found
controls@lloisc0-work:~$ 973mV unlock
973mV: command not found
controls@lloisc0-work:~$ Pin 5.47+-0.014.4
No command 'Pin' found, did you mean:

 

 D1300507

Applying First Contact for the optics cleaning

PD alignment / scattering photos

Cabling

Cabling (final) 

[Koji, Jeff]

The L1 OMC finally sent out from Caltech!

  

[Koji Zach Suresh]

The OMC arrived at LLO without any destruction!

• We found that one shock sensor on the box turned red, the other stayed white.
• We brought the Perican case to the changing room and the wrapping was opened in the optics lab.
• The OMC was discovered without any obvious damage. Successful shipment!
• The inspection with a halogen light indicated some amount of particules on the breadboard.
  The both sides of the breadboard were wiped with the cleanroom cloth.
• The First Contact layers on the optics were removed while the ionized nitrogen gas was brew.

[Koji Zach]

We worked on the OMC test over the weekend.

- At the beginning, the measured OMC transmission was ~85% even after subtracting the junk light and sidebands from the calculation.

- A pretty visible (by eye) dust were on CM1. Also a small residue of First Contact was found on the same mirror.

- We applied FC only on CM1 to remove these.

- The measued transmission went up to the level of 96%.

- We swept the incident power from 0.3mW to 30mW in order to see the dependence of the transmission against the incident power.

- The variation of the transmission ~10% was observed (attached figure 1, Red). This was compared with the similar dependence measured at Caltech (Magenta)

- So, the reduction of the transmission was observed as in eLIGO, although the measurements at Caltech and LLO are not consistent.

- Can this be attributed to the dependence of the PD efficiency? We measured the incident power on the PDs together with the preamp DC output. (Figure.2)
  This gives us how the responsivity changes with the incident power.

- Nevertheless, the dependence remains. We'll make more accurate measurement today.

https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=7373

https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=7395

https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=7410

Weights:

Suspension cage and transportation box: 250.8lb
Suspension cage and transportation box: 150.2lb ==> 100.6lb ==> 45,630 g

Metal Breadboard: 7261 g

Glass Breadboard and transportation fixture: 16382 g
Transportation fixture only: 9432 g ==> 6950 g
Added mass (up to now): 300 g ==> 7250 g

Preamp arrangement

This is the analysis of the cavity finesse data taken on  Apr/13/2013 (before baking), May/30/2013 (after baking), and Jun/02/2013 (after cleaning).
If we believe this result, baking contaminated the cavity, and the first contact removed it. That agrees with the power measurement of the transmitted light.

OMC installed in HAM6!
https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=7486

http://nodus.ligo.caltech.edu:8080/Cryo_Lab/799

(KA: Returned upon H1OMC building)

Analysis of the PZT scan / TF data taken on May 31st and Jun 1st.

[DC scan]

Each PZT was shaken with 10Vpp 1Hz triangular voltage to the thorlabs amp.
The amp gain was x15. Abut 4 TEM00 peaks were seen on a sweep between 0 and 10V.

The input voltage where the peaks were seen was marked. Each peak was mapped on the
corresponding fringe among four. Then the each slope (up and down) was fitted by a iiner slope.
Of course, the PZTs show hystersis. Therefore the result is only an approximation.

PZT1: PZT #26, Mirror C6 (CM1)
PZT2: PZT #23, Mirror C5 (CM2)

PZT arrangement [ELOG Entry]

PZT1:
Ramp Up        13.21nm/V
Ramp Down   13.25nm/V
Ramp Up        13.23nm/V
Ramp Down   13.29nm/V

=> 13.24+/-0.02 nm/V

PZT2:
Ramp Up        13.27nm/V
Ramp Down   12.94nm/V
Ramp Up        12.67nm/V
Ramp Down   12.82nm/V

=> 12.9+/-0.1 nm/V

[AC scan]

The OMC cavity was locked with the fast laser actuation. Each PZT was shaken with a FFT analyzer for transfer function measurments.
(No bias voltage was given)

The displacement data was readout from the laser fast feedback. Since the UGF of the control was above 30kHz, the data was
valid at least up to 30kHz. The over all calibration of the each curve was adjusted so that it agrees with the DC response of the PZTs (as shown above).

The response is pretty similar for these two PZTs. The first series resonance is seen at 10kHz. It is fairly high Q (~30).

Yesterday, Jeff and I bonded the PZT assemblies (#3/#4).
The attached is the arrangement of the components

PZT Assembly #5/#6 were glued on Fri Aug 9th

They are removed from the fixture on Mon Aug 12th.

All of the four PZT assemblies were moved to the OMC lab.

OMC(002)

Cavity Mirrors

FM1 (input coupler): A9
FM2 (output coupler): A13
CM1 (curved mirror close to FM1): C9 (PZT ASSY #6 /  M6 /PZT21/C9)
CM2 (curved mirror close to FM2): C4 (PZT ASSY #4 / M11/PZT25/C4)

DCPD path

BS3 (BS for DCPDs): B10

QPD path

BS1 (input steering): E3
SM1 (steering mirror next to BS1): E5
BS2 (BS for QPD path): B9
SM2 (steering mirror next to BS2): E1
SM3 (steering mirror next to SM2): E2