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ID Date Author Type Category Subjectup
  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
IMG_7589.jpg
Attachment 2: IMG_7590.jpg
IMG_7590.jpg
Attachment 3: IMG_7591.jpg
IMG_7591.jpg
Attachment 4: IMG_7592.jpg
IMG_7592.jpg
  332   Mon Apr 15 00:08:32 2019 KojiGeneralGeneralOMC(004): PZT sub-assembly post air-bake inspection (Sub-assy #7)

Sub-ASSY #7

Probably the best glued unit among the four.

Attachment #1: Mounting Block SN001

Attachment #2: PZT-Mounting Block bonding looks completely wet. Excellent.

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

Attachment #4: Overall look.

Attachment #5: The mirror-PZT bonding also look excellent. The mounting block surface has many EP30-2 residue. But they were shaved off later. The center area of the aperture is clear.

Attachment #6: A small fracture of the mirror barrel is visible (at 7 o'clock).

 

Attachment 1: IMG_7609.jpg
IMG_7609.jpg
Attachment 2: IMG_7610.jpg
IMG_7610.jpg
Attachment 3: IMG_7611.jpg
IMG_7611.jpg
Attachment 4: IMG_7612.jpg
IMG_7612.jpg
Attachment 5: IMG_7613.jpg
IMG_7613.jpg
Attachment 6: IMG_7614.jpg
IMG_7614.jpg
  333   Mon Apr 15 00:39:04 2019 KojiGeneralGeneralOMC(004): PZT sub-assembly post air-bake inspection (Sub-assy #8)

Sub-ASSY #8

Probably the best glued unit among the four.

Attachment #1: Mounting Block SN007

Attachment #2: Overall look.

Attachment #3: Some fracture on the barrel visible.

Attachment #4: It is visible that a part of the PZT removed. Otherwise, PZT-Mounting Block bonding looks pretty good.

Attachment #5: The other side of the PZT bonding. Looks fine.

Attachment #6: Fractured PZT visible on the fixture parts.

Attachment #7: Fractured glass parts also visible on the fixture parts.

Attachment #8: MIrror bonding looks fine except for the glass chip.

Attachment 1: IMG_7601.jpg
IMG_7601.jpg
Attachment 2: IMG_7602.jpg
IMG_7602.jpg
Attachment 3: IMG_7603.jpg
IMG_7603.jpg
Attachment 4: IMG_7604.jpg
IMG_7604.jpg
Attachment 5: IMG_7605.jpg
IMG_7605.jpg
Attachment 6: IMG_7607.jpg
IMG_7607.jpg
Attachment 7: IMG_7608.jpg
IMG_7608.jpg
Attachment 8: IMG_7616.jpg
IMG_7616.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
IMG_7594.jpg
Attachment 2: IMG_7595.jpg
IMG_7595.jpg
Attachment 3: IMG_7596.jpg
IMG_7596.jpg
Attachment 4: IMG_7597.jpg
IMG_7597.jpg
Attachment 5: IMG_7598.jpg
IMG_7598.jpg
Attachment 6: IMG_7600.jpg
IMG_7600.jpg
Attachment 7: IMG_7618.jpg
IMG_7618.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.
We additionally display the impedance to ensure none of them degrades.

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

  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
IMG_7620.jpg
Attachment 2: IMG_7623.jpg
IMG_7623.jpg
Attachment 3: IMG_7629.jpg
IMG_7629.jpg
Attachment 4: IMG_7630.jpg
IMG_7630.jpg
Attachment 5: IMG_7631.jpg
IMG_7631.jpg
Attachment 6: IMG_7632.jpg
IMG_7632.jpg
Attachment 7: IMG_7633.jpg
IMG_7633.jpg
Attachment 8: P_20190416_091537.jpg
P_20190416_091537.jpg
Attachment 9: IMG_7634.JPG
IMG_7634.JPG
  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.

 

  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
190508.png
Attachment 2: scattering_spots_CM1.png
scattering_spots_CM1.png
  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
misalignment2.pdf
Attachment 2: misalignment3.pdf
misalignment3.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
misalignment.pdf misalignment.pdf
  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
misalignment.pdf misalignment.pdf misalignment.pdf
  352   Mon Apr 22 19:54:28 2019 KojiGeneral OMC(004): Spot positions at the end of Apr 22nd
Attachment 1: misalignment4.pdf
misalignment4.pdf
  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
IMG_7635_packaging_of_sn06.JPG
Attachment 2: IMG_7637_engraving_of_sn06.JPG
IMG_7637_engraving_of_sn06.JPG
Attachment 3: IMG_7641_particulate_before_top_gun_large_face.JPG
IMG_7641_particulate_before_top_gun_large_face.JPG
Attachment 4: IMG_7644_particulate_before_top_gun_small_face.JPG
IMG_7644_particulate_before_top_gun_small_face.JPG
Attachment 5: IMG_7646_particulate_after_top_gun.JPG
IMG_7646_particulate_after_top_gun.JPG
  326   Wed Apr 10 19:22:24 2019 KojiGeneralGeneralOMC(004): preparation for the PZT subassembly bonding

Preparation for the PZT subassembly bonding (Section 6.2 and 7.3 of T1500060 (aLIGO OMC optical testing procedure)
- Gluing fixture (Qty 4)
- Silica sphere powder
- Electric scale
- Toaster oven for epoxy mixture qualification

- M prisms
- C prisms
- Noliac PZTs

- Cleaning tools (forceps, tweezers)
- Bonding kits (copper wires, steering sticks)
- Thorlabs BA-2 bases Qty2
- Razor blades

  327   Thu Apr 11 10:54:38 2019 StephenGeneralGeneralOMC(004): preparation for the PZT subassembly bonding
Quote:

Preparation for the PZT subassembly bonding (Section 6.2 and 7.3 of T1500060 (aLIGO OMC optical testing procedure)
- Gluing FIxture (Qty4)
- Silica Sphere Powder
- Electric scale
- Toaster Oven for epoxy mixture qualification

- M prisms
- C prisms
- Noliac PZTs

- Cleaning tools (forceps, tweezers)
- Bonding kits (copper wires, steering sticks)
- Thorlabs BA-2 bases Qty2
- Razor Blades

 

Also brought to the 40m on 10 April, in preparation for PZT subassembly bonding:

- new EP30-2 epoxy (purchased Jan 2019, expiring Jul 2019 - as documented on documents attached to glue, also documented at C1900052.

- EP30-2 tool kit (maintained by Calum, consisting of mixing nozzles, various spatulas, etc)

 

Already at the 40m for use within PZT subassembly bonding:

- "dirty" ABO A with temperature controller (for controlled ramping of curing bake)

- clean work areas on laminar flow benches

- Class B tools, packaging supplies, IPA "red wipes", etc.

 

Upon reviewing EP30-2 procedure T1300322 (current revision v6) and OMC assembly procedure E1300201 (current revision v1) it appears that we have gathered everything required.

  167   Sat Sep 7 17:20:56 2013 KojiGeneralGeneralOMC/PD lab optical table wrapping

[Koji Jeff]

In order to prepare for the splinkler installation on the HEPA enclosure, the table with the optics was wrapped with Ameristat sheets.

Attachment 1: P9064377.JPG
P9064377.JPG
  152   Fri Aug 16 16:36:19 2013 KojiOpticsGeneralOptics List

Link to the "Mirror/PZT Characterization links"

Breadboard

BB1 OMC(001) OMC
BB2 OMC(002) OMC
BB3 -
BB4 OMC(003) OMC

BB5 -
BB6 -

Mounting Prisms:

M01
M02
M06 OMC(002) CM1 (PZT ASSY #6)

M07
M10 OMC(003) CM1 (PZT ASSY #5)

M11 OMC(002) CM2 (PZT ASSY #4)
M12
M13 OMC(003) CM2
(PZT ASSY #3)
M14
M15
M16 OMC(001) CM1 (PZT ASSY #1)
M17
M20 OMC(001) CM2 (PZT ASSY #2)
M21
M22 

Mirror A:
A1  fOMC FM1
A2
  Fullerton for the scattering measurement
A3  fOMC FM2
A4 
A5 
A6  OMC(003) FM2
A7  OMC(001) FM2
A8  OMC(001) FM1
A9  OMC(002) FM1
A10
A11
A12 OMC(003) FM1
A13 OMC(002) FM2
A14 

Mirror B:
B1 
B2 
B3  OMC(001) BS2 (QPD)
B4 
B5  OMC(003) BS2 (QPD)
B6 

B7  OMC(001) BS3 (DCPD)
B8 

B9  OMC(002) BS2 (QPD)
B10 OMC(002) BS3 (DCPD)
B11

B12 OMC(003) BS3 (DCPD)

Mirror C:

C1 OMC(003) CM1 (PZT ASSY #5)
C2 Fullerton for the scattering measurement

C3 OMC(003) CM2 (PZT ASSY #3)
C4 OMC(002) CM2 (PZT ASSY #4)
C5 OMC(001) CM2 (PZT ASSY #2)
C6 OMC(001)
CM1 (PZT ASSY #1)
C7 fOMC CM1
C8 fOMC CM2 -> OMC(002) CM1 (PZT ASSY #6)

C9 OMC(002) CM1 (PZT ASSY #6) -> BURNT
C10 (Liyuan tested)
C11 (Liyuan tested)
C12 curvature untested, faux OMC CM2
C13 curvature untested

Mirror E:
E1  OMC(002) SM2
E2  OMC(002) SM3
E3  OMC(002) BS1
E4  OMC(001) SM2

E5  OMC(002) SM1
E6 
E7  OMC(003) BS1
E8  OMC(003) SM1
E9 

E10 OMC(001) BS1
E11
E12 OMC(001) SM1
E13 OMC(003) SM2
E14
E15
E16 OMC(001) SM3
E17 OMC(003) SM3
E18

PZT:
PZT11
PZT12
PZT13
PZT14 OMC(003) CM1 (PZT ASSY #5)
PZT15 OMC(003) CM2 (PZT ASSY #3)
PZT21 OMC(002) CM1 (PZT ASSY #6)
PZT22
PZT23 OMC(001) CM2 (PZT ASSY #2)
PZT24
PZT25 OMC(002) CM2 (PZT ASSY #4)
PZT26 OMC(001) CM1 (PZT ASSY #1)

 

 

  241   Tue Sep 8 11:18:10 2015 KojiOpticsCharacterizationPBS Transmission measurement

Motivation: Characterize the loss of the Calcite Brewster PBS.

Setup: (Attachment 1)

- The beam polarization is rotated by an HWP
- The first PBS filters out most of the S pol
- The second PBS further filters the S and also confirms how good the polarization is.

- The resulting beam is modulated by a chopper disk. The chopping freq can be 20~1kHz.

- The 50:50 BS splits the P-pol beam into two. One beam goes to the reference PD. The other beam goes to the measurement PD.

- Compare the transfer functions between RefPD and MeasPD at the chopping frequency with and without the DUT inserted to the measurement pass.

- The PBS shift the beam significantly. The beam can't keep the alignment on the Meas PD when the crystal is removed.
  Therefore the "On" and "Off" states are swicthed by moving the PBS and the steering mirror at the same time.
  The positions and angles of the mounts are defined by the bases on the table. The bases are adjusted to have the same spot position for these states as much as possible.

Device Under Test:

Brewster polarizer https://dcc.ligo.org/LIGO-T1300346

The prisms are aligned as shown in Attachment 2

Between the prisms, a kapton sheet (2MIL thickness) is inserted to keep the thin air gap between them.

Result:

Set1: (~max power without hard saturation)
PD1(REF) 10dB Gain (4.75kV/A) 6.39V
PD2(PBS) 10dB Gain (4.75kV/A) Thru 4.77V, PBS 4.75
Chopping frequency 234Hz, FFT 1.6kHz span AVG 20 (1s*20 = 20s)

Thru 0.748307, PBS 0.745476 => 3783 +/- 5 ppm loss
Thru 0.748227, PBS 0.745552 => 3575 +/- 5 ppm
Thru 0.748461, PBS 0.745557 => 3879 +/- 5 ppm
Thru 0.748401, PBS 0.745552 => 3806 +/- 5 ppm
Thru 0.748671, PBS 0.745557 => 4159 +/- 5 ppm
=> Loss 3841 +/- 2 ppm

Set2: (half power)
PD1(REF) 10dB Gain (4.75kV/A) 3.20V
PD2(PBS) 10dB Gain (4.75kV/A) Thru 2.38V, PBS 2.37
Chopping frequency 234Hz, FFT 1.6kHz span AVG 20 (1s*20 = 20s)

Thru 0.747618, PBS 0.744704 => 3898 +/- 5 ppm loss
Thru 0.747591, PBS 0.744690 => 3880 +/- 5 ppm
Thru 0.747875, PBS 0.744685 => 4265 +/- 5 ppm
Thru 0.747524, PBS 0.744655 => 3838 +/- 5 ppm
Thru 0.747745, PBS 0.744591 => 4218 +/- 5 ppm
=> Loss 4020 +/- 2 ppm

Set3: (1/4 power)
PD1(REF) 10dB Gain (4.75kV/A) 1.34V
PD2(PBS) 10dB Gain (4.75kV/A) Thru 1.00V, PBS 0.999
Chopping frequency 234Hz, FFT 1.6kHz span AVG 20 (1s*20 = 20s)

Thru 0.745140, PBS 0.741949 => 4282 +/- 5ppm loss
Thru 0.745227, PBS 0.741938 => 4413 +/- 5ppm
Thru 0.745584, PBS 0.741983 => 4830 +/- 5ppm
Thru 0.745504, PBS 0.741933 => 4790 +/- 5ppm
Thru 0.745497, PBS 0.741920 => 4798 +/- 5ppm
Thru 0.745405, PBS 0.741895 => 4709 +/- 5ppm
=> Loss 4637 +/- 2ppm


Possible improvement:

- Further smaller power
- Use the smaller gain as much as possible
- Compare the number for the same measurmeent with the gain changed

- Use a ND Filter instead of HWP/PBS power adjustment to reduce incident S pol
- Use a double pass configuration to correct the beam shift by the PBS

To be measured

- Angular dependence
- aLIGO Thin Film Polarizer
- HWP
- Glasgow PBS

Attachment 1: setup.JPG
setup.JPG
Attachment 2: CaF2Prism.jpg
CaF2Prism.jpg
Attachment 3: CaF2Prism2.JPG
CaF2Prism2.JPG
  242   Wed Sep 9 01:58:34 2015 KojiOpticsCharacterizationPBS Transmission measurement

Calcite Brewster PBS Continued

The transmission loss of the Calcite brewster PBS (eLIGO squeezer OFI) was measured with different conditions.
The measured loss was 3600+/-200ppm.
(i.e. 900+/-50 ppm per surface)
The measurement error was limited by the systematic error, probably due to the dependence of the PD response on the spot position.


I wonder if it is better to attenuate the beam by a ND filter instead of HWP+PBS.

o First PBS power adjustment -> full power transmission, OD1.0 ATTN Full Power
   PDA20CS Gain 10dB
   Thru 0.746711, PBS 0.744155 => Loss L = 3423 +/- 5ppm

o Same as above, PDA20CS Gain 0dB (smaller amplitude = slew rate less effective?)
   Thru 0.748721, PBS 0.746220 => L = 3340 +/- 5ppm

o Same as above but OD1.4 ATTN
   Thru 0.744853, PBS 0.742111 => L = 3681 +/- 5ppm

o More alignment, more statistics
(PDA20CS 0dB gain =  0.6A/W, 1.51kV/A)
PD(REF, 0dB) 0.426V = 0.47W
PD(MEAS, 0dB) Thru 0.320V, PBS 0.318V = 0.35W, L = 6000+/-3000ppm

Chopping 234Hz, TF 1.6kHz AVG10
Thru 0.745152, PBS 0.742474 => 3594 +/- 5 ppm
Thru 0.745141, PBS 0.742467 => 3589 +/- 5ppm
Thru 0.745150, PBS 0.742459 => 3611 +/- 5ppm
Thru 0.745120, PBS 0.742452 => 3581 +/- 5ppm
Thru 0.745153, PBS 0.742438 => 3644 +/- 5ppm
=> 3604ppm +/-25ppm

o More power

Attenuation OD 1.0
PD(REF, 0dB) 0.875V = 0.97W
PD(MEAS, 0dB) Thru 0.651V, PBS 0.649V = 0.72W, L = 3100+/-1600ppm

Chopping 234Hz, TF 1.6kHz AVG10
Thru 0.746689, PBS 0.743789 => 3884 +/- 5ppm
Thru 0.746660, PBS 0.743724 => 3932 +/- 5ppm
Thru 0.746689, PBS 0.743786 => 3888 +/- 5ppm
Thru 0.746663, PBS 0.743780 => 3861 +/- 5ppm
Thru 0.746684, PBS 0.743783 => 3885 +/- 5ppm
=> 3890ppm +/- 26ppm

o Much less power

Attenuation OD 2.4
PD(REF, 0dB) 67.1mV = 74.0mW
PD(MEAS, 0dB) Thru 53.7V, PBS 53.5V = 59mW, L = 3700+/-1900ppm

Thru 0.745142, PBS 0.742430 => 3640 +/- 5ppm
Thru 0.745011, PBS 0.742557 => 3294 +/- 5ppm
Thru 0.744992, PBS 0.742537 => 3295 +/- 5ppm
Thru 0.745052, PBS 0.742602 => 3288 +/- 5ppm
Thru 0.745089, PBS 0.742602 => 3338 +/- 5ppm
=> 3371ppm +/- 151ppm

o Much less power, but different gain

Attenuation OD 2.4
PD(REF, 20dB) 662mV = 73.1mW
PD(MEAS, 20dB) Thru 501V, PBS 500V = 55.3mW, L = 2000+/-2000ppm

Thru 0.744343, PBS 0.741753 => 3480 +/- 5ppm
Thru 0.744304, PBS 0.741739 => 3446 +/- 5ppm
Thru 0.744358, PBS 0.741713 => 3553 +/- 5ppm
Thru 0.744341, PBS 0.741719 => 3523 +/- 5ppm
Thru 0.744339, PBS 0.741666 => 3591 +/- 5ppm
=> 3519ppm +/- 58ppm


Using the last 4 measurements, mean loss is 3596, and the std is 218. => Loss = 3600+/-200ppm

  172   Wed Oct 16 19:16:29 2013 KojiOpticsCharacterizationPD alignment

 

 shim 1.5mm 001/002

  252   Sun Mar 6 02:13:28 2016 KojiOpticsCharacterizationPD glass reflections

On friday, I removed a glass cover of a G30655 with a PD can cutter.

When a beam shoots a Perkin Elmer/Excelitas PD, we usually observe three reflections.
We always wonder what these are.

When the glass window is illuminated by a beam, I could see two reflections. So they are the front and rear reflection from the glass windows.

Attachment 1: P3048124.JPG
P3048124.JPG
Attachment 2: P3048125.JPG
P3048125.JPG
  174   Wed Oct 23 02:45:07 2013 KojiGeneralGeneralPD realignment

DCPD2 got misaligned during the cable installation. The PD alignment procedure have been gone through again.

Cavity locking

- Removed the FC layers for the cavity related mirrors.

- Aligned and locked the cavity.

PD alignment

- Loosen DCPD2. Checked the reflection with a IR card. Checked the spot on the PD with an IR viewer.

- Finger-tight the screws. Check the reflection with the card again. Check the pot on the PD with a CCD.

- If the spot positions are not satisfactory repeat the process.

- If the spot positions are satisfactory, take pictures of the CCD image.

- Fixing screws for all of the PDs/QPDs were tighten by the torque driver with a torque od 1.75 inch lb.

PD QE measurements

- Measure the power incident on the PDs.

- Set up the transimpedance amp to check the photo current.

- PD1 (T side) 9.10+/-0.03 V 13.02 +/- 0.01W -> QE ~80%

- PD2 (R side) 8.70+/-0.01 V 12.53 +/- 0.01W -> QE ~80%

- These are not strange values considering the presence of the glass caps.

PZT polarity check

- The connections between the PZT electrodes and the pins were checked.

- The positive side is marked by a knot on the wire.

FC painting

- The new FC bottle was brought from Downs, thanks to Margot.

 

  111   Tue Apr 16 00:40:45 2013 KojiOpticsGeneralPD/QPD path gluing ~ preparation

[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.

  276   Tue Mar 28 21:04:27 2017 KojiElectronicsCharacterizationPDH amp

Attachment 1: PDH amp RF part (before the preamp was installed)

Attachment 2: RF-AF transmission

Attachment 3: Attachment 3: LO dependence

Attachment 4: RF amp gain (saturation)

Attachment 5: Input/output noise level

Attachment 6: Attachment 6: Preamp/DCPD out buffer AF circuit

Attachment 1: DSC_0269.JPG
DSC_0269.JPG
Attachment 2: RF_to_AF_conversion.pdf
RF_to_AF_conversion.pdf
Attachment 3: LO_dependence.pdf
LO_dependence.pdf
Attachment 4: RFamp_gain.pdf
RFamp_gain.pdf
Attachment 5: PreampNoise.pdf
PreampNoise.pdf
Attachment 6: preamp.png
preamp.png
  286   Sat Jul 29 18:44:38 2017 ranaElectronicsCharacterizationPDH amp

attachment 6: DCPD preamp looks like the opamp is wired for positive feedback?

  287   Sat Jul 29 21:42:51 2017 KojiElectronicsCharacterizationPDH amp

The polarities indicated in the right circuits were opposite, obviously.

  313   Sat Jan 12 22:49:11 2019 KojiOpticsCharacterizationPM-SM patch cable mode cleaning effect

Mode cleaning capability of an optical fiber was measured. The conclusion is that the leakage of the non-fiber mode to the fiber output is insignificant and also practically negligible.

The tested fiber was Thorlabs 5-m Polarization Maintaining Single-Mode fiber (P3-1064PM-FC-5, PM Patch Cable, PANDA, 1064 nm, FC/APC, 5m).

The output mode cleaner was used as a mode analyzer. The fiber input was aligned and the misaligned so that the amount of higher order mode for the fiber is changed. The fiber output has been mode matched to an output mode cleaner. Therefore excess mode mismatch when the fiber input was misaligned, was accounted as the leakage higher order mode.

For each alignment state, the OMC transmission (in V), the OMC reflection (in V), and the OMC reflection with the OMC unlocked were measured. The voltages were measured with a digital multimeter (non-portable unit). With the fiber input beam aligned to the fiber, the fiber input and output powers were measured with a power meter.

With the input beam aligned
- Fiber input: 52.5 +/- 0.2 [mW]
- Fiber output: 35.5 +/- 0.2 [mW] (~68% coupling)
- Reflection PD offset: -0.00677 +/- 0.00001 [V]

- Refl PD reading with the OMC unlocked: 6.32 +/- 0.01 [V]
- Refl PD reading with the OMC locked: 0.133 +/- 0.002 [V]
- OMC Trans PD with the OMC locked: -1.72 +/- 0.01 [V] 

With the input beam misaligned
- Refl PD reading with the OMC unlocked: 3.63 +/- 0.01 [V]
- Refl PD reading with the OMC locked: 0.0752 +/- 0.001 [V]
- OMC Trans PD with the OMC locked: -1.00 +/- 0.01 [V] 

The naive mode matching was 0.9779 +/- 0.0003 and 0.9775 +/- 0.0003 without and with misalignment. We initially had roughly 17mW of non-fiber mode incident. And it was increased by roughly 15mW. For the misaligned case, the amount of the OMC-matched carrier was also reduced due to the misalignment. So the actual fiber mode cleaning effect needs more careful quantitative analysis.


The power budget at each part of the setup was modeled as shown in Attachment 1. The blue numbers are the measured values.
The factor a is the ratio of the leakage non-fiber mode into the fiber transmission.
The factor (1-b) is the mode matching of the fiber mode into the OMC mode.

\begin{align} P_{\rm omcrefl} & = a P_{\rm nofib} + b P_{\rm fib} \nonumber \\ P_{\rm fibout} & = P_{\rm omcrefl} + (1-b) P_{\rm fib} \nonumber \\ P_{\rm tot} & = P_{\rm nofib} + P_{\rm fib} \nonumber \end{align}

and

\begin{align} P'_{\rm omcrefl} &= a P'_{\rm nofib} + b P'_{\rm fib} \nonumber \\ P'_{\rm fibout} &= P'_{\rm omcrefl} + (1-b) P'_{\rm fib} \nonumber \\ P_{\rm tot} &= P'_{\rm nofib} + P'_{\rm fib} \nonumber \end{align}

With the calibration between the refl PD and the power meter measurement,
  \begin{align} P_{\rm tot} &= 52.5 \pm 0.2 {[mW]} \nonumber \\ P_{\rm fibout} &= 35.5 \pm 0.2 {\rm [mW]} \nonumber \end{align}
\begin{align} P_{\rm omcrefl} &= 0.78 \pm 0.01\,\,{\rm [mW]} \nonumber \\ P'_{\rm omcrefl} &= 0.460 \pm 0.006\,\,{\rm [mW]} \nonumber \\ P'_{\rm fibout} &= 20.4 \pm 0.13 \,\,{\rm [mW]} \nonumber \end{align}

The solution of the equations is
\begin{align} a &= (4 \pm 4) \times 10^{-4} \nonumber \\ b &= 0.0219 \pm 0.0005 \nonumber \end{align}

So, the leakage of the non-fiber mode to the fiber output is insignificant. Moreover, the number is practically negligible because the mismatching between the fiber and OMC modes is of the order of percent and dominated by the aberration of the collimator (i.e. the OMC reflection looks like concentric higher-order LG modes) with the order of 1~2%.
 

Attachment 1: fiber_mode_cleaning.pdf
fiber_mode_cleaning.pdf
  103   Mon Apr 8 20:56:52 2013 KojiOpticsConfigurationPZT & Curverd Mirror arrangement

Assembly #1:

Mounting Prism #16
PZT #26
Mirror C6

Assembly #2:

Mounting Prism #20
PZT #23
Mirror C5

Attachment 1: PZT_assembly.pdf
PZT_assembly.pdf PZT_assembly.pdf
  149   Fri Aug 9 10:09:56 2013 KojiGeneralGeneralPZT Assembly #3/#4

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

Attachment 1: PZT_assembly.pdf
PZT_assembly.pdf PZT_assembly.pdf PZT_assembly.pdf
  150   Mon Aug 12 20:22:19 2013 KojiGeneralGeneralPZT Assembly #5/#6

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.

  148   Sat Jul 6 17:10:07 2013 KojiMechanicsCharacterizationPZT Response analysis

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).

Attachment 1: PZT_Scan.pdf
PZT_Scan.pdf
Attachment 2: L1OMC_PZT_Response.pdf
L1OMC_PZT_Response.pdf
  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
Diagrams_SubAssembly.pdf Diagrams_SubAssembly.pdf
Attachment 2: C10_C13_Combinations.pdf
C10_C13_Combinations.pdf C10_C13_Combinations.pdf
Attachment 3: Plots_Config_Tolerance.pdf
Plots_Config_Tolerance.pdf
  102   Mon Apr 8 11:49:18 2013 KojiMechanicsCharacterizationPZT actuator tested at LLO

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
  104   Mon Apr 8 21:11:14 2013 KojiOpticsGeneralPZT assembly gluing

[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)

  106   Tue Apr 9 13:56:09 2013 KojiOpticsGeneralPZT assembly post gluing / pre baking pictures

 

 

  77   Sat Mar 23 13:34:14 2013 KojiOpticsGeneralPZT assembly prototype glued

Prototype PZT assembly

Motivation:

Before we glue the PZT assembly, we need to build a prototype. This is to confirm the heat cure process
does not cause any cracking of the PZT or glass components. The CTE of the PZT is 2~3ppm
(depends on the direction) while the one for Fused Silica is 0.55ppm.

Materials:

- A fused silica substrate, 1/2" in dia. Supplied from Garilynn. I defined the chamfered side as the front side.

- PZT: Noliac NAC2124, serial #24, this is a spare PZT as this has the worst length to angle coupling.

- Mounting Prism: D1102069 SN22. This has the worst perpendicularity among the prisms.

- Fixtures:

D1300185 aLIGO OMC CURVED MIRROR BONDING FIXTURE ASSY
D1300186 aLIGO OMC CURVED MIRROR BONDING FIXTURE FRONT
D1300187 aLIGO OMC CURVED MIRROR BONDING FIXTURE BACK
D1300188 aLIGO OMC CURVED MIRROR BONDING FIXTURE RING

P3223322.jpg

Procedure:

- Wipe all of the components with the isopropanol.

- Attach the back piece of the fixture on the Al wrapped bracket.
(The current 4-40 screws for the middle piece are too long and stick out from the back side of the back piece.
Therefore a 1/16" shim for a 1/2" rod is inserted between the bracket and the back piece)

- Brought a glue package to the lab (10:40PM)

- Loosely attach the middle piece to the back piece with four 4-40 screws.

- Insert the mounting prism in the fixture. Insert the PZT in the fixture too.

- Insert a dummy substrate in the fixture.

- Attach the front piece with spring loaded screws.

- Align the PZT and the optic in the fixture. (Basically apply downward force to them)

- Test the rigidity of the assembly (11:30PM)

- Remove the PZT and the mirror. Apply UV epoxy.
(A single dub was applied for each PZT surface of the PZT but this was too much.)

- Make sure the PZT and the optic are aligned by applying the downward force.

- Illuminate UV light from the front.

- Illuminate UV light from the back. (11:50PM)

Procedural issues:

- Long 4-40 screws (described above)
(Circumvented)

- As the PZT is not constrained with the middle piece, it tends to move vertically and rotationally
because of the wire tension. (This is not a mistake but the design so that the PZT is constrained by the optic.)
Therefore after applying glue on the PZT, the motion of the PZT spreads the glue on the back surface of
the curved mirror.

(Solution to be tried) Our solution is to glue the PZT and the mounting prism first with a dummy optics (made of SF2).
The wires should be tacked somewhere on the mount 

- The amount of glue on the PZT was too much. I gave one dub of glue for each side.
As a result, excess glue leaks out along the ring.

- The front plate has a chamfered hole but this tends to slip and move the mirror vertically.
Later I used the flat side of the plate to hole the mirror.
(Circumvented) It seems that this hold the mirror in a better way as the plate can't rock

- Spring load for the front plate was too strong. This was because the natural length of the spring was too long.
(Circumvented) The spring was cut at the length of the 4-40 screw. Then attaching the screws became completely fine.

P3223323.jpg


Result:

P3233336.jpg P3233348.jpg

Slide show:

  202   Tue Jul 8 18:54:54 2014 KojiMechanicsCharacterizationPZT characterization

Each PZT was swept with 0-150V 11Hz triangular wave.
Time series data for 0.2sec was recorded for each PZT.

The swept voltage at the resonances were extracted and the fringe number was counted.
Some hysteresis is seen as usual.

The upward/downward slopes are fitted by a linear line.

The average displacement is 11.3nm/V for PZT1 and 12.7nm/V.

The PZT response was measured with a FFT analyzer. The DC calibration was adjusted by the above numbers.

Attachment 1: PZT_Scan.pdf
PZT_Scan.pdf
Attachment 2: I1OMC_PZT_Response.pdf
I1OMC_PZT_Response.pdf
  314   Fri Feb 1 12:52:12 2019 KojiMechanicsGeneralPZT deformation simulation

A simple COMSOL simulation was run to see how the PZT deforms as the voltage applied.

Use the geometry of the ring PZT which is used in the OMCs -  NAC2124 (OD 15mm, ID 9mm, H 2mm)
The material is PZT-5H (https://bostonpiezooptics.com/ceramic-materials-pzt) which is predefined in COMSOL and somewhat similar to the one used in NAC2124 (NCE51F - http://www.noliac.com/products/materials/nce51f/)
The bottom surface of the ring was electrically grounded (0V), and mechanically fixed.
Applied 100V between the top and bottom.

 

Attachment 1: pzt.png
pzt.png
  156   Thu Aug 22 15:40:15 2013 KojiElectronicsConfigurationPZT endurance test

[Koji, Jeff]

Background

In response to the failure of one of the PZTs on L1OMC (LLO:8366), we have been taking place an endurance test of
the four PZT sub-assemblies in prior to their being glued on the glass breadboard.

According to the technical note by Noliac, the common mode of PZT failure is degradation of the impedance
due to cyclic actuation (like 10^7 times) with over voltage. Therefore our procedure of the test to actuate the PZTs
at least 10^7 times with half voltage of the nominal operating voltage (i.e. nominal 200V) and check the degradation
of the impedance.

Driving signal

For the driving of the PZT, a thorlabs HV amp is used. A source signal of 3.5Vpp with an offset of 1.7V is produced
by DS345 function generator. This signal turns to a sinusoidal signal between 0 and 100V in conjunction with the gain
of 15 at the HV amp.

The maximum driving frequency is determined by the current supply limit of the HV amp (60mA). The capacitance
of each PZT is 0.47uF. If we decide to cycle the signal for 4 PZTs in parallel, the maximum frequency achievable
without inducing voltage drop is 100Hz. This yields the test period of 28hours in order to achive 10^7 cycles.

P8214340.jpg

Initial impedance diagnosis

To check the initial state of the PZTs, a DC voltage of 100V was applied via 1kOhm output resistance.
(Note that this output resistance is used only for the impedance test.)
For each PZTs, both side of the resister showed 99.1V for all measurement by a digital multimeter.
Assuming the minimum resolution (0.1V) of the multimeter, the resistance of each PZT was more than 1MOhm before
the cycling test.

Failure detection

In order to detect any impedance drop of the PZTs, the driving signal is monitored on the oscilloscope via a 1:10 probe.
If there is any significant impedance drop, the driver can't provide the driving current correctly. This can be found
by the deviation of the driving voltage from the reference trace on the oscilloscope (below).

P8214337.jpg

Temperature rise

Because of the loss angle of the PZT capacitance, heating of the PZTs is expected. In order to check the temperature rise,
an IR Viewer (FLIR) was used. We did not take care of careful calibration for the PZT emissibity as what we want was a
rough estimation of the temperature.

Before the driving (LEFT) and at the equilibrium (RIGHT)
IR_0457.jpg
IR_0461.jpg

The temperature change of the PZT was tracked for an hour (below). Fitting of the points indicated that the temperature rise is 2.3degC and the
time constant of 446 sec. This level of temperature rise is totally OK. (Note that the fitting function was T = 27.55 - 2.31 Exp[-t/446.])

 

Results

DAY1:

Start driving
20:27 25.2 degC, status OK
20:33 26.7 degC, status OK
20:41 26.9 degC, status OK
20:48 27.6 degC, status OK
20:54 27.4 degC, status OK
21:10 27.4 degC, status OK
21:37 status OK
Stop driving

70 minutes of driving (i.e. 4.2x10^5 cycles) => no sign of degradation

DAY2:

Start driving
14:15, 24.5 degC, status OK
14:17, 26.0 degC, status OK
14:24, 27.0 degC, status OK
14:40, 26.8 degC, status OK
14:50, 26.8 degC, status OK
15:30, 26.8 degC, status OK
15:55 status OK
17:40 status OK
21:00 status OK (2.43Mcycles + 0.42Mcycles = 2.85Mcycles)
1d+12:00 status OK (7.83Mcycles + 0.42Mcycles = 8.25Mcycles)
1d+15:00 status OK (8.91Mcycles + 0.42Mcycles = 9.33Mcycles)
1d+18:40 status OK (10.23Mcycles + 0.42Mcycles = 10.65Mcycles)
Stop Driving

After 10.65Mcycles no sign of degradationwas found.

  157   Fri Aug 23 19:24:32 2013 KojiElectronicsConfigurationPZT endurance test (II)

The PZT tests were finished with the conclusion that the PZT won't be damaged with our expected usage.


This is another test of the PZTs to make sure small (~10V) reverse voltage does not break the PZTs.

Background

At the site, we decided to use one of the PZT, which is still alive, for the HV and LV actuation.
The HV actuation is limited to 0 to 100V while the LV actuation is 10Vdc with 1Vpp fast dithering.
This means that a reverse voltage upto 10.5V will be applied to the PZT at the worst case.

From the technical note this level of reverse voltage does not induce polarization of the PZT.
The test is to ensure the PZT is not damaged or degraded by this small reverse voltage.

Method

HV drive: Thorlabs HV amp (G=15) driven with DS345 function generator (3.5Vpp+1.7Vdc, 0.1Hz)
=> 0-100V @0.1Hz
=> The hot side of the potential is connected to the positive side of the PZT

LV drive: Phillips function generator (1Vpp+9.5Vdc@1kHz)
The driving frequency is limited by the current output of the function generator.
=> The hot side of the potential is connected to the negative side of the PZT

These drives shares the common ground.

Tests

Testing with spare PZTs 

Started @19:23 (Aug 23)
Stopped @20:15+2d (Aug 25, duration 48h52m)
17600cycles for the 0.1Hz drive.
176Mcycles for the 1kHz drive.

Checked the impedances of PZT1 and PZT2.

Apply 100Vdc via a 1kOhm resister, 0V detected across the 1kOhm resister
This is equivalent to the resistance of 1MOhm.

 

Testing with the PZT subassemblies

Started shaking of the four PZT assemblies @20:20 (Aug 25)
No impedance change observed @11:10+1d
No impedance change observed @15:30+1d
Stopped shaking of the four PZT assemblies @XXXX (Aug 26)

 

Wiring for the test

PZT_shaking.png

 

 

  328   Thu Apr 11 12:15:31 2019 KojiMechanicsConfigurationPZT sub assy mirror orientations
Attachment 1: PZT_subassy.png
PZT_subassy.png
Attachment 2: PZT_subassy.pdf
PZT_subassy.pdf PZT_subassy.pdf PZT_subassy.pdf PZT_subassy.pdf
  312   Thu Jan 10 20:45:00 2019 KojiOpticsCharacterizationPZT test cable

As OMC SN002 already has the PZTs connected to the Mighty-Mouse connector, a test cable with a female mighty-mouse connector was made.

A small imperfection: When the cable was inserted to the connector shell, I forgot to mirror the pin out. Therefore the color and pin number do not match.

Attachment 1: OMC_PZT_wiring.pdf
OMC_PZT_wiring.pdf
  203   Thu Jul 10 01:39:38 2014 KojiElectronicsGeneralPZT wire

Rich came to the OMC lab. Pins for the mighty mouse connector were crimped on the 4 PZT wires.
We found the male 4pin mighty mouse connector in the C&B area.

The cable inventory was checked with ICS/DCC combo. It turned out that most of the on-board cables
are at LHO. We decided to send the OMC there and then the cables are installed at the site.

Attachment 1: P7096669.JPG
P7096669.JPG
  5   Thu Jun 21 03:07:27 2012 ZachOpticsConfigurationParameter selection / mode definition

EDIT 2 (ZK): As with the previous post, all plots and calculations here are done with my MATLAB cavity modeling utility, ArbCav.

EDIT (ZK): Added input q parameters for OMMT 

found the nice result that the variation in the optimal length vs. variation in the mirror RoC is roughly linear within the ±1% RoC tolerance. So, we can choose two baseline mode definitions (one for each mirror topology) and then adjust as necessary following our RoC measurements.

Bowtie

For R = 2.5 m, the optimal length (see previous post) is LRT = 1.150 m, and the variation in this is dLRT/dR ~ +0.44 m/m.

Here is an illustration of the geometry:

geom_bowtie.png

The input q parameters, defined at the point over the edge of the OMC slab where the beam first crosses---(40mm, 150mm) on the OptoCad drawing---are, in meters:

  • qix = - 0.2276 + 0.6955 i
  • qiy = - 0.2276 + 0.6980 i

 

Non-bowtie

For R = 2.5 m, the optimal length is LRT = 1.246 m, and the variation in this is also dLRT/dR ~ +0.44 m/m.

Geometry:

geom_non-bowtie.png

q parameters, defined as above:

  • qix = - 0.0830 + 0.8245 i
  • qiy = - 0.0830 + 0.8268 i
  17   Mon Aug 13 17:01:35 2012 KojiCleanGeneralParticle Counts

Aug 13, 2012 / 0.5um 1000~2000/(0.1 cu ft) / 0.7um   400-600/(0.1 cu ft) by ATF particle counter (MET ONE 227A)

They are counts/(0.1 ft^3)! These numbers should be multiplied by 10 to know the particle "CLASS".

  20   Tue Sep 25 14:18:14 2012 KojiCleanGeneralParticle Counts

Particle counts

Before the prefilter is installed: 0.5um 1191cnts, 0.7um 346cnts

2:20 prefilter installed
2:25 0.5um 650 / 0.7um 255
3:00 0.5um 578 / 0.7um 99
4:00 0.5um 480 / 0.7um 102
5:00 0.5um 426 / 0.7um 76

They are counts/(0.1 ft^3)! These numbers should be multiplied by 10 to know the particle "CLASS".

  21   Mon Oct 1 16:06:55 2012 KojiCleanGeneralParticle Counts

1. It turned out that the particle counter MET ONE 227A at ATF shows
(particle count)/(0.1 ft^3)


This means that the numbers I saw previously should be multiplied by 10.
So the nominal class of the room was 5000.

2. As our GT-321s have no diffuser, I borrowed a diffuser from 227A.
The diffuser actually increases the count. We need to buy them.
All the measurments below are performed with the diffuser and calibrated in Count/ft^3.

3. Measured the particle level without the HEPA running.

With diffuser: [cnt/ft^3]

  GT-321 #1 GT-321 #2   227A
0.3um 152622 137511 -
0.5um  14706 14823   11860

Over Class 10000

4. The two HEPA fans are turned on at the speed "MED".

Basically no particles are detected in the HEPA booth.

With diffuser, inside of the HEPA booth:

  GT-321 #1 GT-321 #2  227A 
0.3um 0 0
-
0.5um 0 0 0

The particle level in the room (outside of the HEPA booth) is also improved

With diffuser, outside of the HEPA booth GT-321 #1:
0.3 um 18612
0.5 um   1728

5. The two HEPA fans are turned on at the speed "LOW".

Particle levels are still zero inside.

With diffuser, inside of the HEPA booth, GT-321 #1:
0.3 um 0
0.5 um 0

The particle level in the room (outside of the HEPA booth) is also improved
but the cleaning power for 0.3um seems degraded.

With diffuser, outside of the HEPA booth, GT-321 #1:
0.3 um 34488
0.5 um   1386

 

  398   Fri Oct 23 19:09:54 2020 KojiGeneralGeneralParticle counter transfered to Radhika

See this entry: https://nodus.ligo.caltech.edu:8081/40m/15642

  63   Thu Feb 21 18:44:18 2013 KojiOpticsConfigurationPerpendicularity test

Perpendicularity test of the mounting prisms:

The perpendicularity of the prism pieces were measured with an autocollimator.

Two orthogonally jointed surfaces forms a part of a corner cube.
The deviation of the reflected image from retroreflection is the quantity measured by the device.

When the image is retroreflected, only one horizontal line is observed in the view.
If there is any deviation from the retroreflection, this horizontal line splits into two
as the upper and lower halves have the angled wavefront by 4x\theta. (see attached figure)

The actual reading of the autocollimator is half of the wavefront angle (as it assumes the optical lever).
Therefore the reading of the AC times 30 gives us the deviation from 90deg in the unit of arcsec.

SN / measured / spec

SN10: 12.0 arcsec (29 arcsec)

SN11: 6.6 arcsec (16 arcsec)

SN16: 5.7 arcsec (5 arcsec)

SN20: -17.7 arcsec (5 arcsec)

SN21: - 71.3 arcsec (15 arcsec)

 

Attachment 1: perpendicularity_test.pdf
perpendicularity_test.pdf perpendicularity_test.pdf
Attachment 2: P2203206.JPG
P2203206.JPG
  246   Tue Dec 15 13:39:13 2015 KojiElectronicsCharacterizationPhase noise measurement of aLIGO EOM drivers

This measurement has been done on Dec 1st, 2015.


The phase noise added by the EOM driver was tested.

The test setup is depicted in the attached PDF. The phase of the RF detector was set so that the output is close to zero crossing as much as possible with the precision of 0.5ns using a switchable delay line box. The phase to voltage conversion was checked by changing the delayline by 1ns. This gave me somewhat larger conversion factor compared to the sine wave test using an independent signal generator. This was due to the saturation of the phase detector as the LO and RF both have similar high RF level for the frequency mixer used.

The measurement has done with 1) no EOM driver involved, 2) one EOM driver inserted in the RF path, and 3) EOM drivers inserted in both the LO and RF paths.

I could not understand why the measurement limit is so high. Also the case 2 seems too low comsidering the noise level for 1) and 3).

At least we could see clear increase of the noise between the case 1) and 3). Therefore, we can infer the phase noise added by the EOM driver from the measurements.

Note: The additional phase noise could be associated with the original amplitude noise of the oscillator and the amplitude-to-phase conversion by the variable attenuator. This means that the noise could be corellated between two EOM drivers. The true test could be done using a PLL with a quiet VCO. Unfortuantely I don't have a good oscillator sufficient for this measurement.

Attachment 1: phase_noise.pdf
phase_noise.pdf phase_noise.pdf phase_noise.pdf
Attachment 2: phase_noise_9MHz.pdf
phase_noise_9MHz.pdf
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