40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  OMC elog, Page 1 of 9  Not logged in ELOG logo
New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Typedown Category Subject
  18   Tue Aug 14 03:29:06 2012 KojiSupplyGeneralClean supply rack

Clean supplies & some cleaning tools are located at the right side of the entrance.
The file cabinet there was moved to the left side of the door, but will be removed eventually.

P8131959.JPG    P8131961.JPG

  123   Fri May 10 09:33:22 2013 KojiSupplyGeneralCOMSOL simulation on the glass bracket stress

COMSOL1.png

  274   Thu Jan 19 20:57:53 2017 KojiSupplyGeneralPurchase

Ordered:

Office Depot
v AA battery Qty. 24
v 9V battery Qty. 4
v Floor cable cover (6ft)

Thorlabs
v HV PZT Driver
v Lenses

  275   Thu Feb 16 17:23:12 2017 KojiSupplyGeneralPurchase

 

  321   Thu Apr 4 20:07:39 2019 KojiSupplyGeneralPurchase

== Office Depot ==
Really Useful Box 9L x 6 (delivered)
Really Useful Box 17L x 5 (ordered 4/4)
P-TOUCH tape (6mm, 9mm, 12mmx2, 18mm) (ordered 4/4)

== Digikey ==
9V AC Adapter (- inside, 1.3A) for P-TOUCH (ordered 4/4)
12V AC Adapter (+ inside, 1A) for Cameras (ordered 4/4)

== VWR ==
Mask KIMBERLY CLARK "KIMTECH Pure M3" ISO CLASS 3 (ordered 4/4)

  375   Wed Sep 18 22:30:11 2019 StephenSupplyGeneralEP30-2 Location and Status

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

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

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

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

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

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

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

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

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

Attachment 1: IMG_5217.JPG
IMG_5217.JPG
  376   Wed Sep 18 23:16:06 2019 StephenSupplyGeneralItems staged at 40m Bake Lab for PZT Subassembly Bonding

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

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

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

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

 

Attachment 1: IMG_5216.JPG
IMG_5216.JPG
Attachment 2: IMG_5215.JPG
IMG_5215.JPG
  384   Tue Oct 22 11:56:09 2019 StephenSupplyGeneralEpoxy Status update as of 22 October 2019

The following is the current status of the epoxies used in assembly of the OMC (excerpt from C1900052)

Re-purchasing efforts are underway and/or complete

Attachment 1: image_ep30-2_epoxy_kit_pcs_item_1582_location_downs_3303.JPG
image_ep30-2_epoxy_kit_pcs_item_1582_location_downs_3303.JPG
  407   Fri Feb 5 07:40:37 2021 StephenSupplyGeneralOMC Unit 4 Build Machined Parts

OMC Unit 4 Build Machined Parts are currently located in Stephen's office. See image of large blue box from office, below.

Loaned item D1100855-V1-00-OMC08Q004 to Don Griffith for work in semi-clean HDS assy.

This includes mass mounting brackets, cable brackets, balance masses, etc. For full inventory, refer to ICS load Bake-9527 (mixed polymers) and Bake-9495 (mixed metals).

Inventory includes all items except cables. Plasma sprayed components with slight chipping were deemed acceptable for Unit 4 use. Cable components (including flex circuit) are ready to advance to fabrication, with a bit more planning and ID of appropriate wiring.

Attachment 1: IMG_8117.JPG
IMG_8117.JPG
  411   Wed Jul 7 14:21:50 2021 StephenSupplyGeneralOMC Unit 4 Build Machined Parts

More explicit insights into the inventory for the Unit 4 build. Image of inventory included below.

Machined Parts:

Cable Components:

  • Hughes Circuits made us Kapton flex circuits. These have not been processed in any way.
  • Rich had supplied a spool of Gore 4-conductor in-vacuum wire (see below image). I returned the sppol for Rich but it is living in Downs and available for use.
  • PEEK cable ties were damaged during bake, and will be replaced by SYS inventory.

Retrofit/Repair Capabilities:

  • Aluminum reinforcement brackets D1600316
  • Glass reinforcement brackets (Edmund Optics 45-072 and 45-071)

ref: E1900034 and other associated documents.

Attachment 1: IMG_9238.JPG
IMG_9238.JPG
Attachment 2: IMG_9236.JPG
IMG_9236.JPG
  4   Wed Jun 20 20:37:45 2012 ZachOpticsConfigurationTopology / parameter selection

EDIT (ZK): All the plots here were generated using my MATLAB cavity modeling tool, ArbCav. The utility description is below. The higher-order mode resonance plots are direct outputs of the function. The overlap plots were made by modifying the function to output a list of all HOM resonant frequencies, and then plotting the closest one as a function of cavity length. This was done for various values of highest mode order to consider, as described in the original entry.

Description:

This function calculates information about an arbitrary optical cavity. It can plot the cavity geometry, calculate the transmission/reflection spectrum, and generate the higher-order mode spectrum for the carrier and up to 2 sets of sidebands.

The code accepts any number of mirrors with any radius of curvature and transmission, and includes any astigmatic effects in its output.

As opposed to the previous version, which converted a limited number of cavity shapes into linear cavities before performing the calculation, this version explicitly propagates the gouy phase of the beam around each leg of the cavity, and is therefore truly able to handle an arbitrary geometry.

----------------Original Post----------------

I expressed concern that arbitrarily choosing some maximum HOM order above which not to consider makes us vulnerable to sitting directly on a slightly-higher-order mode. At first, I figured the best way around this is to apply an appropriate weighting function to the computed HOM frequency spacing. Since this will also have some arbitrariness to it, I have decided to do it in a more straightforward way. Namely, look at the spacing for different values of the maximum mode number, nmax, and then use this extra information to better select the length.

Assumptions:

  • The curved mirror RoC is the design value of 2.50±0.025 m
  • The ±9 MHz sidebands will have ~1% the power of the other fields at the dark port. Accordingly, as in Sam's note, their calculated spacing is artificially increased by 10 linewidths.
  • The opening angle of 4º is FIXED, and the total length is scaled accordingly

Below are the spacing plots for the bowtie (flat-flat-curved-curved) and non-bowtie (flat-curved-flat-curved) configurations. Points on each line should be read out as "there are are no modes of order N or lower within [Y value] linewidths of the carrier TEM00 transmission", where N is the nmax appropriate for that trace. Intuitively, as more orders are included, the maxima go down, because more orders are added to the calculation.

*All calculations are done using my cavity simulation function, ArbCav. The mode spacing is calculated for each particular geometry by explicitly propagating the gouy phase through each leg of the cavity, rather than by finding an equivalent linear cavity*

 ovlp_bowtie.pngovlp_non-bowtie.png

Since achievable HOM rejection is only one of the criteria that should be used to choose between the two topologies, the idea is to pick one length solution for EACH topology. Basically, one maximum should be chosen for each plot, based on how how high an order we care about.

Bowtie

For the bowtie, the nmax = 20 maximum at L = 1.145 m is attractive, because there are no n < 20 modes within 5 linewidths, and no n < 25 modes within ~4.5 linewidths. However, this means that there are also n < 10 modes within 5 linewidths, while they could be pushed (BLUE line) to ~8.5 linewidths at the expense of proximity to n > 15 modes.

Therefore, it's probably best to pick something between the red and green maxima: 1.145 m < L < 1.152 m.

By manually inspecting the HOM spectrum for nmax = 20, it seems that L = 1.150 m is the best choice. In the HOM zoom plot below and the one to follow, the legend is as follows

  • BLUE: Carrier
  • GREEN: +9 MHz
  • RED: -9 MHz
  • CYAN: +45 MHz
  • BLACK: -45 MHz

spect_zoom_bowtie.png

Non-bowtie

Following the same logic as above, the most obvious choice for the non-bowtie is somewhere between the red maximum at 1.241 m and the magenta maximum at 1.248 m. This still allows for reasonable suppression of the n < 10 modes without sacrificing the n < 15 mode suppression completely.

Upon inspection, I suggest L = 1.246 m

spect_zoom_non-bowtie.png

I reiterate that these calculations are taking into account modes of up to n ~ 20. If there is a reason we really only care about a lower order than this, then we can do better. Otherwise, this is a nice compromise between full low-order mode isolation and not sitting directly on slightly higher modes.

 

RoC dependence

One complication that arises is that all of these are highly dependent on the actual RoC of the mirrors. Unfortunately, even the quoted tolerance of ±1% makes a difference. Below is a rendering of the RED traces (nmax = 20) in the first two plots, but for R varying by ±2% (i.e., for R = 2.45 m, 2.50 m, 2.55 m).

ovlp_vs_R_bowtie.pngovlp_vs_R_non-bowtie.png

The case for the non-bowtie only superficially seems better; the important spacing is the large one between the three highest peaks centered around 1.24 m.

Also unfortunately, this strong dependence is also true for the lowest-order modes. Below is the same two plots, but for the BLUE (nmax = 10) lines in the first plots.

 ovlp_vs_R_N10_bowtie.pngovlp_vs_R_N10_non-bowtie.png

Therefore, it is prudent not to pick a specific length until the precise RoC of the mirrors is measured.

 

Conclusion

Assuming the validity of looking at modes between 10 < n < 20, and that the curved mirror RoC is the design value of 2.50 m, the recommended lengths for each case are:

  • Bowtie: LRT = 1.150 m
  • Non-bowtie: LRT = 1.246 m

 HOWEVER, variation within the design tolerance of the mirror RoC will change these numbers appreciably, and so the RoC should be measured before a length is firmly chosen.

  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
  6   Fri Jun 29 11:26:04 2012 ZachOpticsCharacterizationRoC measurement setup

Here is the proposed RoC measurement setup. Koji tells me that this is referred to as "Anderson's method".

We would like to use a linear cavity to measure the RoC of the curved mirrors independently (before forming the ring cavity), since the degeneracy of HOMs will make the fitting easier.

  • An NPRO is PDH locked to a linear cavity formed of a high-quality flat mirror on one end, and the OMC curved optic on the other.
  • A second, broadband EOM is placed after the first one, and its frequency is swept with a VCO to generate symmetric sidebands about the carrier
  • A TRANS RFPD's signal is demodulated at the secondary EOM frequency, to give a DC signal proportional to HOM transmission
  • This HOM scan is fit to a model, with RoC the free parameter. Since there are two sidebands, the HOM spectrum of the model must be folded about the carrier frequency.
  • To get a good signal, we should slightly misalign the input beam, allowing for higher overlap with HOMs.

If we decided that the symmetric sidebands are too unwieldy, or that we have issues from sidebands on sidebands, we can accomplish the same style measurement using an AOM-shifted pickoff of the pre-PDH EOM beam. The advantage of the former method is that we don't have to use any polarization tricks.

RoC_measurement_setup.png

Attachment 2: RoC_measurement_setup.graffle.zip
  8   Wed Jul 18 23:20:13 2012 KojiOpticsCharacterizationMode scan results of ELIGO

Nic Smith sent me a bunch of elog lists where the results of the mode scan can be found.

From Nic:

There have been many mode scan analyses done at LLO:
http://ilog.ligo-la.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=06/07/2008&anchor_to_scroll_to=2008:06:07:20:55:41-jrsmith
http://ilog.ligo-la.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=06/16/2008&anchor_to_scroll_to=2008:06:16:17:47:11-waldman
http://ilog.ligo-la.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=08/06/2009&anchor_to_scroll_to=2009:08:06:12:23:16-kissel
http://ilog.ligo-la.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=09/25/2009&anchor_to_scroll_to=2009:09:25:20:57:47-kate

We didn't do as much of this at LHO. At some point we were trying to figure out how the arm cavity mode was different from the carrier mode:
http://ilog.ligo-wa.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=04/17/2009&anchor_to_scroll_to=2009:04:17:23:15:05-kawabe
http://ilog.ligo-wa.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=03/27/2009&anchor_to_scroll_to=2009:03:27:21:38:14-kawabe

http://ilog.ligo-wa.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=02/18/2009&anchor_to_scroll_to=2009:02:18:20:15:00-kawabe

Here's a long mode scan that was done, and the data is attached to the elog, but none of the amplitudes are analyzed.
http://ilog.ligo-wa.caltech.edu/ilog/pub/ilog.cgi?group=detector&date_to_view=07/08/2009&anchor_to_scroll_to=2009:07:08:17:02:19-nicolas

  9   Sun Jul 22 15:56:53 2012 ZachOpticsCharacterizationRoC measurement setup

Here is a more detailed version of the setup, so that we can gather the parts we will need.

detailed_RoC_setup.png

Parts list:

  • Optics, etc.:
    • 1 NPRO
    • 2 QWP
    • 3 HWP
    • 2 PBS
    • 2 EOM (at least one broadband)
    • 2 RFPD (at least one very-high-bandwidth for TRANS, e.g., 1611)
    • 1 CCD camera
    • OMC curved mirrors to be tested
    • 1 low-loss flat reference mirror with appropriate transmission (e.g., G&H, ATF, etc.)
    • ~3 long-ish lenses for MMT, EOM focusing
    • ~2 short lenses for PD focusing
    • 1 R ~ 80% power splitter for TRANS (can be more or less)
    • ~7 steering mirrors
    • ~3 beam dumps
    • Mounts, bases, clamps, hardware
  • Electronics:
    • 1 fixed RF oscillator (e.g., DS345, etc.)
    • 1 VCO (e.g., Marconi, Tektronix, etc.)
    • 2 Minicircuits RF mixers
    • 2 Minicircuits RF splitters
    • 2 SMA inline LPFs
    • Locking servo (SR560? uPDH? PDH2?)
    • Some digital acquisition/FG system
    • Power supplies, wiring and cabling.

Quote:

Here is the proposed RoC measurement setup. Koji tells me that this is referred to as "Anderson's method".

We would like to use a linear cavity to measure the RoC of the curved mirrors independently (before forming the ring cavity), since the degeneracy of HOMs will make the fitting easier.

  • An NPRO is PDH locked to a linear cavity formed of a high-quality flat mirror on one end, and the OMC curved optic on the other.
  • A second, broadband EOM is placed after the first one, and its frequency is swept with a VCO to generate symmetric sidebands about the carrier
  • A TRANS RFPD's signal is demodulated at the secondary EOM frequency, to give a DC signal proportional to HOM transmission
  • This HOM scan is fit to a model, with RoC the free parameter. Since there are two sidebands, the HOM spectrum of the model must be folded about the carrier frequency.
  • To get a good signal, we should slightly misalign the input beam, allowing for higher overlap with HOMs.

 

Attachment 2: detailed_RoC_setup.graffle.zip
  22   Fri Oct 5 03:39:58 2012 KojiOpticsGeneralRoC Test setup

Based on Zach's experiment design, I wrote up a bit more detailed optical layout for the mirror test.

RoC_test_setup.png

Item: Newfocus Fast PD
Qty.: 1
Mirror: Newfocus Fast PD
Mount: Post
Post: Post Holder (Newfocus)
Fork: Short Fork

Item: Thorlabs RF PD
Qty.: 1
Mirror: Thorlabs RF PD
Mount: Post
Post: Post Holder (Newfocus)
Fork: Short Fork

Item: Newfocus Broadband
Qty.: 1
Mirror: Newfocus EOM
Mount: Newfocus
Post: Custom Mount? or Pedestal X"?
Fork: Short Fork

Item: Newfocus Resonant
Qty.: 1
Mirror: Newfocus EOM
Mount: Newfocus
Post: Custom Mount? or Pedestal X"?
Fork: Short Fork

Item: ND Filter
Qty.: 2
Mirror: -
Mount: Thorlabs FIlter Holder
Post: Pedestal X"
Fork: Short Fork

Item: New Port Lens Kit 1"
Qty.: 1

Item: Thorlabs ND Kit
Qty.: 1

Item: Plano Convex Lens
Qty.: f=100, 100, 150, 200
Mirror: New Port (AR)
Mount: Thorlabs
Post: Post Holder (Newfocus)
Fork: Short Fork

Item: Bi-Convex Lens
Qty.: 75
Mirror: New Port (AR)
Mount: Post
Post: Post Holder (Newfocus)
Fork: Short Fork

Item: Flipper Mirror
Qty.: 1
Mirror: CVI Y1-10XX-45P
Mount: New Focus Flipper
Post: Pedestal X"
Fork: Short Fork

Item: Steering Mirror
Qty.: 8
Mirror: CVI Y1-10XX-45P
Mount: Suprema 1inch
Post: Pedestal X"
Fork: Short Fork

Item: PBS
Qty.: 3
Mirror: PBS 1inch BK7
Mount: Newport BS Mount
Post: Pedestal X"
Fork: Short Fork

Item: Knife Edge Beam Dump
Qty.: 4
Mirror: Thorlabs Knife Edge
Mount: Post
Post: Post Holder (Newfocus)
Fork: Short Fork

Item: Half Wave Plate
Qty.: 4
Mirror: CVI QWPO-
Mount: CVI
Post: Pedestal X"
Fork: Short Fork

Item: Quater Wave Plate
Qty.: 3
Mirror: CVI QWPO-
Mount: CVI
Post: Pedestal X"
Fork: Short Fork

Item: OMC Curved Mirror
Qty.: 2
Mirror: -
Mount: Suprema 0.5inch + Adapter
Post: Pedestal X"
Fork: Short Fork

Item: Prism Holder
Qty.: 1
Mirror: OMC Prism
Mount: Newport Prism Mount
Post: Pedestal X"
Fork: Short Fork

Item: CCD
Qty.: 1
Mirror: Thorlabs?
Mount: Thorlabs?
Post: Post Holder (Newfocus)
Fork: Short Fork

Attachment 1: RoC_test_setup.pdf
RoC_test_setup.pdf
  23   Mon Oct 8 11:30:47 2012 KojiOpticsGeneralEG&G 2mm photodiode angle response

EGE&G 2mm photodiode angle response measured by Sam T1100564-v1

  24   Tue Oct 9 04:59:24 2012 KojiOpticsGeneralOMC Test Optical Setup

OMC_test_setup.png

 

Attachment 2: OMC_test_setup.pdf
OMC_test_setup.pdf
  26   Fri Oct 12 17:15:19 2012 KojiOpticsGeneralLoan from the 40m / ATF
  • HWP set
    • Optics: CVI QWPO-1064-08-2-R10
    • Mount: New Focus #9401
    • Post: Pedestal 2.5inch
    • Returned: Oct 19, 2012 by KA
  • QWP set
    • Optics: CVI QWPO-1064-05-4-R10
    • Mount: New Focus #9401
    • Post: Pedestal 2.5inch
    • Returned: Jan 17, 2013 by KA
  • Faraday set
    • Optics: OFR IO-2-YAG-HP Returned: Mar 21, 2013 by KA
    • Mount: New Focus #9701 Returned: Apr 17, 2013 by KA
    • Post: Pedestal (1.5+0.25inch)x2
  • Steering Mirror 1
    • Optics: CVI Y1-1037-45S
    • Mount: Newport Ultima U100-AC
    • Post: Pedestal 3inch
    • Returned: Jan 17, 2013 by KA
  • Steering Mirror 2
    • Optics: CVI Y1-1037-45P
    • Mount: Newport Ultima U100-AC
    • Post: Pedestal 3inch
    • Returned: Jan 17, 2013 by KA
  • Steering Mirror 3
    • Optics: New Focus 5104
    • Mount: Newport Ultima U100-AC
    • Post: Pedestal 3inch
    • Returned: Jan 17, 2013 by KA
  • Prism Mount
    • Mount: Thorlabs KM100P+PM1 2014/7/17
    • Post: Pedestal 1.5+1+1/8inch
  • 0.5" Mirror Mount
    • Mount: Newport U50-AReturned: Apr 17, 2013 by KA
    • Mount: Newport U50-A 2014/7/17
    • Post: Pedestal 1.5+2inch
  • Black Glass Beam Dump
    • Optics: 1" sq. schott glass x3
    • Mount: Custom Hexagonal 1"
    • Post: Pedestal 3inch
  • PBS Set
    • 05BC16PC.9 (PBS 1064 1000:1)
    • Mount: Custom Aluminum
    • Returned: Jan 17, 2013 by KA
  • Lenses
    • KBX067.AR33 f=125mm
    • KPX106 f=200mm, KPX109 f=250mm unknown-coat
    • KPX088.AR33 f=75mm
    • KPX094.AR33 f=100mm
    • PLCX-C (BK7) 3863 (f=7.5m), 2060 (f=4.0m), 1545 (f=3.0m), 1030 (f=2.0m) non-coat
    • PLCX-UV (FS) 30.9 non-coat(!) f=60mm
    • Returned: Jan 17, 2013 by KA
  • Pedestals
    • 1/4" x5, 1/8" x3, Returned: Jan 17, 2013 by KA
    • 0.5" x1, 1.5" x1

Another loan from the 40m on Oct 17th, 2012

  • Minicircuits
    • Splitter ZFSC-2-5 x2
    • Filter SLP-1.9 x2 / BLP-1.9 x1/2 / SLP-5 x1
    • Returned: Jan 17, 2013 by KA
  • Connectors / Adaptors
    • SMA TEE x1 / SMA 50Ohm x 1 / BNC T x 10, Returned: Jan 17, 2013 by KA
    • SMA TEE x1 / SMA 50Ohm x 1Returned: May 20, 2013 by KA
  • Pomona Box x1, Returned: Jan 17, 2013 by KA
  • Pomona Box x1
  • Power supply for New Focus Fast PD made by Jamie R Returned: Apr 17, 2013 by KA
  • BS-1064-50-1037-45S / Newport U100-A mount / 1"+2" Pedestal, Returned: Jan 17, 2013 by KA
  • BS-1064-50-1025-45P / Newport U100-A mount / 3/4" post + Base, Returned: Jan 17, 2013 by KA
  • BNC cable 21ft x2, Returned: Jan 17, 2013 by KA
  • SMA Cable 6ft

 


Another loan from the 40m on Nov 21th, 2012

  • Mounting Base Thorlabs BA-2 x 17
  • Mounting Posts (phi=3/4", L=2.65", normal x15, and 1/4"-20 variant x2)

Yet another loan from the 40m on Jan 16th, 2013

  • V-groove Mounting Bases Custom. Qty.2Returned: Feb 25, 2013 by KA

Loan from ATF

32.7MHz EOM+Tilt aligner
Thorlabs Broadband EOM+Tilt aligner
Forks x 5Returned: Feb 25, 2013 by KA
JWIN Camera x 2

  30   Wed Oct 17 20:36:04 2012 KojiOpticsGeneralRoC test cavity locked

The RoC test setup has been built on the optical table at ATF.

The cavity formed by actual OMC mirrors have been locked.

The modulation frequency of the BB EOM was swept by the network analyzer.
A peak at ~30MHz was found in the transfer function when the input beam was misaligned and clipping was introduced at the transmission PD.
Without either the misalignment or the clipping, the peak disappears. Also the peak requires these imperfections to be directed in the same way
(like pitch and picth, or yaw and yaw). This strongly suggests that the peak is associated with the transverse mode.

The peak location was f_HOM = 29.79MHz. If we consider the length of the cavity is L=1.20m, the RoC is estimated as

RoC = L / (1 - Cos[f_HOM/(c/2/L) * PI]^2)

This formula gives us the RoC of 2.587 m.

I should have been able to find another peak at f_FSR-f_TMS. In deed, there was the structure found at 95MHz as expected.
However, the peak was really weak and the location was difficult to determine as it was coupled with the signal from residual RFAM.

The particle level in the clean booth was occasionally measured. Every measurement showed "zero".

To be improved:

  • The trans PD is 1801 which was found in ATF with the label of the 40m. It turned out that it is a Si PD.
    I need to find an InGaAs PD (1811, 1611, or my BBPD) or increase the modulation, or increase the detected light level.
    (==> The incident power on 1810 increased. Oct 17)
  • The BS at the transmission is actually Y1-45P with low incident angle. This can be replaced by 50% or 30% BS to increase the light on the fast PD.
    (==> 50% BS is placed. Oct 17)
  • I forgot to put a 50ohm terminator for the BB EOM.
    (==> 50Ohm installed. Oct 17)
  • A directional coupler could be used for the BBEOM signal to enhance the modulaiton by 3dB.
  • The mode matching is shitty. I can see quite strong TEM20 mode.
  • Use the longer cavity? L=1.8m is feasible on the table. This will move the peak at 27MHz and 56MHz (FSR=83MHz). Very promising.
    (==> L=1.8m, peak at 27MHz and 56MHz found. Oct.17)
Attachment 1: detailed_RoC_setup.pdf
detailed_RoC_setup.pdf detailed_RoC_setup.pdf
Attachment 2: omc_cav_lock_SCRN_SHOT.png
omc_cav_lock_SCRN_SHOT.png
Attachment 3: Cav_scan_response_20121016.pdf
Cav_scan_response_20121016.pdf
  31   Thu Oct 18 20:23:33 2012 KojiOpticsCharacterizationImproved measurement

Significant improvement has been achieved in the RoC measurement.

  • The trans PD has much more power as the BS at the cavity trans was replaced by a 50% BS. This covers the disadvantage of using the a Si PD.
  • The BB EOM has a 50Ohm terminator to ensure the 50Ohm termination at Low freq.
  • The length of the cavity was changed from 1.2m to 1.8m in order to see the effect on the RoC measurement.

By these changes, dramatic increase of the signal to noise ratio was seen.

Now both of the peaks corresponds to the 1st-order higher-order modes are clearly seen.
The peak at around 26MHz are produced by the beat between the carrier TEM00 and the upper-sideband TEM01 (or 10).
The other peak at around 57MHz are produced by the lower-sideband TEM01 (or 10).

 

Peak fitting

From the peak fitting we can extract the following numbers:

  • Cavity FSR (hence the cavity length)
  • Cavity g-factor
  • Approximate measure of the cavity bandwidth

Note that the cavity itself has not been touched during the measurement.
Only the laser frequency and the incident beam alignment were adjusted.

The results are calculated by the combination of MATLAB and Mathemaica. The fit results are listed in the PDF files.
In deed the fitting quality was not satisfactory if the single Lorentzian peak was assumed.

There for two peaks closely lining up with different height. This explained slight asymmetry of the side tails

This suggests that there is slight astigmatism on the mirrors (why not.)

The key points of the results:

- FSR and the cavity length: 83.28~83.31MHz / L=1.799~1.800 [m] (surprisingly good orecision of my optics placement!)

- Cavity g-factor: Considering the flatness of the flat mirror from the phase map, the measured g-factors were converted to the curvature of the curved mirror.
RoC = 2.583~4 [m] and 2.564~7 [m]. (Note: This fluctuation can not be explained by the statistical error.)
The mode split is an order of 10kHz. This number also agrees with the measurement taken yesterday.

If the curved mirror had the nominal curvature of 2.5m, the flat mirror should have the curvature of ~20m. This is very unlikely.

- Approximate cavity line width: FWHM = 70~80kHz. This corresponds to the finesse of ~500. The design value is ~780.
This means that the locking offset is not enough to explain the RoC discrepancy between the design and the measurement.

 

Attachment 1: Cav_scan_response_zoom_20121017.pdf
Cav_scan_response_zoom_20121017.pdf
Attachment 2: detailed_RoC_setup.pdf
detailed_RoC_setup.pdf
  32   Wed Nov 7 01:28:20 2012 KojiOpticsCharacterizationWedge angle test (A1)

Wedge angle test

Result: Wedge angle of Prism A1: 0.497 deg +/- 0.004 deg


 

Principle:

o Attach a rail on the optical table. This is the reference of the beam.

o A CCD camera (Wincam D) is used for reading out spot positions along the rail.

o Align a beam path along the rail using the CCD.

o Measure the residual slope of the beam path. (Measurement A)

o Insert an optic under the test. Direct the first surface retroreflectively. (This means the first surface should be the HR side.)

o Measure the slope of the transmitted beam. (Measurement B)

o Deflection angle is derived from the difference between these two measurements.

Setup:

wedge_measurement_setup.png

o An Al plate of 10" width was clamped on the table. Four other clamps are located along the rail to make the CCD positions reproducible.

o A prism (Coating A, SN: A1) is mounted on a prism mount. The first surface is aligned so that the reflected beam matches with the incident beam
with precision of +/-1mm at 1660mm away from the prism surface. ==> precision of +/- 0.6mrad

o In fact, the deflection angle of the transmission is not very sensitive to the alignment of the prism.
The effect of the misalignment on the measurement is negligible.

o Refractive index of Corning 7980 at 1064nm is 1.4496

Result:

Without Prism
Z (inch / mm), X (horiz [um] +/-4.7um), Y (vert [um] +/-4.7um)
0” / 0, -481.3, -165.1
1.375" / 34.925, -474.3, -162.8
3" / 76.2, -451.0, -186.0
4.375" / 111.125, -432.5, -181.4
6" / 152.4, -432.5, -181.4
7.375" / 187.325, -330.2, -204.6
9" / 228.6, -376.7, -209.3

With Prism / SN of the optic: A1
Z (inch / mm), X (horiz [um] +/-4.7um), Y (vert [um] +/-4.7um)
0” / 0, -658.3, -156.8
1.375" / 34.925, -744.0, -158.1
3" / 76.2, -930.0, -187.4
4.375" / 111.125, -962.6, -181.4
6" / 152.4, -1190.4, -218.6
7.375" / 187.325, -1250.9, -232.5
9" / 228.6, -1418.3, -232.5

Analysis:

Wedge angle of Prism A1: 0.497 deg +/- 0.004 deg

wedge_measurement.png[Click for a sharper image]

  35   Thu Nov 8 13:24:53 2012 KojiOpticsCharacterizationMore wedge measurement

A1
Horiz Wedge    0.497    +/-    0.004 deg
Vert Wedge      0.024    +/-    0.004 deg

A2
Horiz Wedge    0.549    +/-    0.004 deg
Vert Wedge      0.051    +/-    0.004 deg

A3
Horiz Wedge    0.463    +/-    0.004 deg
Vert Wedge      0.009    +/-    0.004 deg

A4
Horiz Wedge    0.471    +/-    0.004 deg
Vert Wedge      0.019    +/-    0.004 deg

A5
Horiz Wedge    0.458    +/-    0.004 deg
Vert Wedge      0.006    +/-    0.004 deg

Attachment 1: wedge_measurement_overall.pdf
wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf
  37   Thu Nov 8 19:52:57 2012 KojiOpticsGeneralHow to apply UV epoxy

KA's question:

Do you know how to apply this epoxy?
Do we need a plunger and a needle for this purpose?

Nic saids:

When we did it with Sam, I seem to remember just squirting some on some foil then dabbing it on with the needle.

Attachment 1: UVepoxy.jpg
UVepoxy.jpg
  38   Thu Nov 8 20:12:10 2012 KojiOpticsConfigurationHow many glass components we need for a plate

Optical prisms 50pcs (A14+B12+C6+E18)
Curved Mirrors 25pcs (C13+D12)

  Qty

Prisms

Curved No BS OMC Wedge tested
Coating A: IO coupler   14 0  2 prisms 5/5
Coating B: BS 45deg   12 0  2 prisms  0/5
Coating C: HR   6 13 2 curved  
Coating D: Asym. output coupler   0 12 -  
Coating E: HR 45deg   18 0  4 prism (1 trans + 3 refl) 0/3
D1102209 Wire Mount Bracket 25      4  
D1102211 PD Mount Bracket 30      8  

 

  39   Fri Nov 9 00:43:32 2012 KojiOpticsCharacterizationFurther more wedge measurement

Now it's enough for the first OMC (or even second one too).
Today's measurements all distributed in theta>0.5deg. Is this some systematic effect???
I should check some of the compeled mirrors again to see the reproducibility...

A1    Horiz Wedge    0.497039    +/-    0.00420005    deg / Vert Wedge     0.02405210    +/-    0.00420061    deg

A2    Horiz Wedge    0.548849    +/-    0.00419993    deg / Vert Wedge     0.05087730    +/-    0.00420061    deg
A3    Horiz Wedge    0.463261    +/-    0.00420013    deg / Vert Wedge     0.00874441    +/-    0.00420061    deg
A4    Horiz Wedge    0.471536    +/-    0.00420011    deg / Vert Wedge     0.01900840    +/-    0.00420061    deg
A5    Horiz Wedge    0.458305    +/-    0.00420014    deg / Vert Wedge     0.00628961    +/-    0.00420062    deg

B1    Horiz Wedge    0.568260    +/-    0.00419988    deg / Vert Wedge    -0.00442885    +/-    0.00420062    deg
B2    Horiz Wedge    0.556195    +/-    0.00419991    deg / Vert Wedge    -0.00136749    +/-    0.00420062    deg
B3    Horiz Wedge    0.571045    +/-    0.00419987    deg / Vert Wedge     0.00897185    +/-    0.00420061    deg
B4    Horiz Wedge    0.563724    +/-    0.00419989    deg / Vert Wedge    -0.01139000    +/-    0.00420061    deg
B5    Horiz Wedge    0.574745    +/-    0.00419986    deg / Vert Wedge     0.01718030    +/-    0.00420061    deg
E1    Horiz Wedge    0.600147    +/-    0.00419980    deg / Vert Wedge     0.00317778    +/-    0.00420062    deg
E2    Horiz Wedge    0.582597    +/-    0.00419984    deg / Vert Wedge    -0.00537131    +/-    0.00420062    deg
E3    Horiz Wedge    0.592933    +/-    0.00419982    deg / Vert Wedge    -0.01082830    +/-    0.00420061    deg

-------

To check the systematic effect, A1 and B1 were tested with different alignment setup.

A1    Horiz Wedge    0.547056    +/-    0.00419994    deg / Vert Wedge    0.0517442    +/-    0.00420061    deg
A1    Horiz Wedge    0.546993    +/-    0.00419994    deg / Vert Wedge    0.0469938    +/-    0.00420061    deg
A1    Horiz Wedge    0.509079    +/-    0.00420003    deg / Vert Wedge    0.0240255    +/-    0.00420061    deg

B1    Horiz Wedge    0.547139    +/-    0.00419994    deg / Vert Wedge    0.0191204    +/-    0.00420061    deg



 

Attachment 1: wedge_measurement_overall.pdf
wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf wedge_measurement_overall.pdf
Attachment 2: 121108a_A1.pdf
121108a_A1.pdf 121108a_A1.pdf 121108a_A1.pdf 121108a_A1.pdf
  40   Sat Nov 17 02:31:34 2012 KojiOpticsCharacterizationMirror T test

Mirror T test

The mirror was misaligned to have ~2deg incident (mistakenly...) angle.

C1: Ptrans = 7.58uW, Pinc = 135.0mW => 56.1ppm

C1 (take2): Ptrans = 7.30uW, Pinc = 134.4mW => 54.3ppm

C2: Ptrans = 6.91uW, Pinc = 137.3mW => 50.3ppm

C3: Ptrans = 6.27uW, Pinc = 139.7mW => 44.9ppm

C4: Ptrans = 7.62uW, Pinc = 139.3mW => 54.7ppm

C5: Ptrans = 6.20uW, Pinc = 137.5mW => 45.1ppm

A1: Ptrans = 1.094mW, Pinc = 133.6mW => 8189ppm

  41   Mon Nov 19 13:33:14 2012 KojiOpticsCharacterizationResuming testing mirror RoCs

In order to resume testing the curvatures of the mirrors, the same mirror as the previous one was tested.
The result looks consistent with the previous measurement.

It seems that there has been some locking offset. Actually, the split peaks in the TF@83MHz indicates
the existence of the offset. Next time, it should be adjusted at the beginning.

Curved mirror SN: C1
RoC: 2.5785 +/- 0.000042 [m]

Previous measurements
=> 2.5830, 2.5638 => sqrt(RoC1*RoC2) = 2.5734 m
=> 2.5844, 2.5666 => sqrt(RoC1*RoC2) = 2.5755 m

Attachment 1: Cav_scan_response_zoom_20121016.pdf
Cav_scan_response_zoom_20121016.pdf
  42   Mon Nov 26 01:40:00 2012 KojiOpticsCharacterizationMore RoC measurement

C1: RoC: 2.57845 +/− 4.2e−05m

C2: RoC: 2.54363 +/− 4.9e−05m

C3: RoC: 2.57130 +/− 6.3e−05m   

C4: RoC: 2.58176 +/− 6.8e−05m

C5: RoC 2.57369 +/− 9.1e−05m

 

==> 2.576 +/- 0.005 [m] (C2 excluded)

Attachment 1: RoC_measurement.pdf
RoC_measurement.pdf RoC_measurement.pdf RoC_measurement.pdf RoC_measurement.pdf RoC_measurement.pdf
  43   Thu Nov 29 21:18:23 2012 KojiOpticsGeneralOMC Mounting Prisms have come

PB293030.JPG

PB293032.JPG

  44   Tue Dec 18 20:04:40 2012 KojiOpticsCharacterizationPrism Thickness Measurement

The thicknesses of the prism mirrors (A1-A5) were measured with micrometer thickness gauge.
Since the thickness of the thinner side (side1) depends on the depth used for the measurement,
it is not accurate. Unit in mm.

A1: Side1: 9.916, Side2: 10.066 => derived wedge angle: 0.43deg
A2: Side1: 9.883, Side2: 10.065 => 0.52
A3: Side1: 9.932, Side2: 10.062 => 0.38
A4: Side1: 9.919, Side2: 10.060 => 0.40
A5: Side1: 9.917, Side2: 10.058 => 0.40

prism.png

  48   Mon Dec 31 03:10:09 2012 KojiOpticsGeneralSolidWorks model of the OMC breadboard
Attachment 1: D1201439_aLIGO_Breadboard_layout_assy_121224.png
D1201439_aLIGO_Breadboard_layout_assy_121224.png
Attachment 2: D1201439_aLIGO_Breadboard_layout_assy_130105.easm
  49   Mon Dec 31 03:11:45 2012 KojiOpticsCharacterizationFurther more RoC measurement

Total (excluding C2, C7, C8): 2.575 +/- 0.005 [m]

New results

C6: RoC: 2.57321 +/− 4.2e-05m

C7: RoC: 2.56244 +/− 4.0e−05m ==> Polaris mount

C8: RoC: 2.56291 +/− 4.7e-05m ==> Ultima mount

C9: RoC: 2.57051 +/− 6.7e-05m

Previous results

C1: RoC: 2.57845 +/− 4.2e−05m

C2: RoC: 2.54363 +/− 4.9e−05m ==> Josh Smith @Fullerton for scattering measurement

C3: RoC: 2.57130 +/− 6.3e−05m   

C4: RoC: 2.58176 +/− 6.8e−05m

C5: RoC 2.57369 +/− 9.1e−05m

Attachment 1: Cav_scan_response_zoom_20121125_C6_9.pdf
Cav_scan_response_zoom_20121125_C6_9.pdf Cav_scan_response_zoom_20121125_C6_9.pdf Cav_scan_response_zoom_20121125_C6_9.pdf Cav_scan_response_zoom_20121125_C6_9.pdf
  50   Wed Jan 2 07:35:55 2013 KojiOpticsCharacterizationThickness of a curved mirror

Measured the thickness of a curved mirror:

Took three points separated by 120 degree.

S/N: C2, (0.2478, 0.2477, 0.2477) in inch => (6.294, 6.292, 6.292) in mm

  51   Wed Jan 2 07:45:39 2013 KojiOpticsCharacterizationFirst Contact test

Conclusion: Good. First contact did not damage the coating surface, and reduced the loss


- Construct a cavity with A1 and C2

- Measure the transmission and FWHM (of TEM10 mode)

- Apply First Contact on both mirrors

- Measure the values again


Transmission:

2.66 +/- 0.01 V -> 2.83  +/- 0.01 V

==> 6.3% +/- 0.5 % increase

FWHM of TEM10:

Before: (66.1067, 65.4257, 66.1746) +/- (0.40178, 0.38366, 0.47213) [kHz]
After: (60.846, 63.4461, 63.7906) +/- (0.43905, 0.56538, 0.51756) [kHz]

==> 5.1% +/- 2.7% decrease

Question: What is the best way to measure the finesse of the cavity?

Attachment 1: Cav_scan_response_zoom_20121125_C2_before.pdf
Cav_scan_response_zoom_20121125_C2_before.pdf
Attachment 2: Cav_scan_response_zoom_20121125_C2_after.pdf
Cav_scan_response_zoom_20121125_C2_after.pdf
  53   Thu Jan 10 18:37:50 2013 KojiOpticsCharacterizationWedging of the PZTs

Yesterday I measured the thickness of the PZTs in order to get an idea how much the PZTs are wedged.

For each PZT, the thickness at six points along the ring was measured with a micrometer gauge.
The orientation of the PZT was recognized by the wire direction and a black marking to indicate the polarity.

A least square fitting of these six points determines the most likely PZT plane.
Note that the measured numbers are assumed to be the thickness at the inner rim of the ring
as the micrometer can only measure the maximum thickness of a region and the inner rim has the largest effect on the wedge angle.
The inner diameter of the ring is 9mm.



The measurements show all PZTs have thickness variation of 3um maximum.

The estimated wedge angles are distributed from 8 to 26 arcsec. The directions of the wedges seem to be random
(i.e. not associated with the wires)



As wedging of 30 arcsec causes at most ~0.3mm spot shift of the cavity (easy to remember),
the wedging of the PZTs is not critical by itself. Also, this number can be reduced by choosing the PZT orientations
based on the estimated wedge directions --- as long as we can believe the measurements.



Next step is to locate the minima of each curved mirror. Do you have any idea how to measure them?

Attachment 1: PZT_wedging.pdf
PZT_wedging.pdf
  54   Wed Jan 16 14:10:50 2013 KojiOpticsCharacterizationAutocollimator tests of optics perpendicularity/parallelism

The items:

- Autocollimator (AC) borrowed from Mike Smith (Nippon Kogaku model 305, phi=2.76", 67.8mm)

- Retroreflector (corner cube)

- Two V grooves borrowed from the 40m

Procedure:

- Autocollimator calibration

o Install the AC on a optical table

o Locate the corner cube in front of the AC.

o Adjust the focus of the AC so that the reflected reticle pattern can be seen.

o If the retroreflection and the AC are perfect, the reference reticle pattern will match with the reflected reticle pattern.

o Measure the deviation of the reflected reticle from the center.

o Rotate the retroreflector by 90 deg. Measure the deviation again.

o Repeat the process until total four coordinates are obtained.

o Analysis of the data separates two types of the error:
   The average of these four coordinates gives the systematic error of the AC itself.
   The vector from the center of the circle corresponds to the error of the retroreflector.

- Wedge angle measurement

 

To be continued

  55   Fri Jan 18 13:25:17 2013 KojiOpticsConfigurationAutocollimator calibration

An autocollimator (AC) should show (0,0) if a retroreflector is placed in front of the AC.
However, the AC may have an offset. Also the retroreflector may not reflect the beam back with an exact parallelism.

To calibrate these two errors, the autocollimator is calibrated. The retroreflector was rotated by 0, 90, 180, 270 deg
while the reticle position are monitored. The images of the autocollimator were taken by my digital camera looking at the eyepiece of the AC.

Note that 1 div of the AC image corresponds to 1arcmin.

Basically the rotation of the retroreflector changed the vertical and horizontal positions of the reticle pattern by 0.6mdeg and 0.1mdeg
(2 and 0.4 arcsec). Therefore the parallelism of the retrorefrector is determined to be less than an arcsec. This is negligibly good for our purpose.

The offset changes by ~1div in a slanted direction if the knob of the AC, whose function is unknown, is touched.
So the knob should be locked, and the offset should be recorded before we start the actual work every time.

Attachment 1: autocollimator_calibration.pdf
autocollimator_calibration.pdf autocollimator_calibration.pdf autocollimator_calibration.pdf autocollimator_calibration.pdf
  56   Sat Jan 19 20:47:41 2013 KojiOpticsCharacterizationWedge measurement with the autocollimator

The wedge angle of the prism "A1" was measured with the autocollimator (AC).

The range of the AC is 40 arcmin. This means that the mirror tilt of 40arcmin can be measured with this AC.
This is just barely enough to detect the front side reflection and the back side reflection.

The measured wedge angle of the A1 prism was 0.478 deg.

Ideally a null measurement should be done with a rotation stage.

Attachment 1: autocollimator_wedge_measurement.pdf
autocollimator_wedge_measurement.pdf
  59   Mon Feb 4 00:39:08 2013 KojiOpticsCharacterizationWedge measurement with the autocollimator and the rotation stage

Method:

  • Mount the tombstone prism on the prism mount. The mount is fixed on the rotation stage.
  • Locate the prism in front of the autocollimator.
  • Find the retroreflected reticle in the view. Adjust the focus if necessary.
  • Confirm that the rotation of the stage does not change the height of the reticle in the view. 

    If it does, rotate the AC around its axis to realize it.
    This is to match the horizontal reticle to the rotation plane.
  • Use the rotation stage and the alignment knobs to find the reticle at the center of the AC.
Make sure the reticle corresponds to the front surface.
  • Record the micrometer reading.
  • Rotate the micrometer of the rotation stage until the retroreflected reticle for the back surface.
  • There maybe the vertical shift of the reticle due to the vertical wedging. Record the vertical shi
  • Record the micrometer reading. Take a difference from the previous value.
     

Measurement:

  • A1: α = 0.68 deg, β = 0 arcmin (0 div)
  • A2: α = 0.80 deg, β = -6 arcmin (3 div down)
  • A3: α = 0.635 deg, β = -1.6 arcmin (0.8 div down)
  • A4: α = 0.650 deg, β = 0 arcmin (0div)
  • A5: α = 0.655 deg, β = +2.4 arcmin (1.2 div up)

Analysis:

  • \theta_H = ArcSin[Sin(α) / n]
  • \theta_V = ArcSin[Sin(β) / n]/2
     
  • A1: \theta_H = 0.465 deg, \theta_V = 0.000 deg
  • A2: \theta_H = 0.547 deg, \theta_V = -0.034 deg
  • A3: \theta_H = 0.434 deg, \theta_V = -0.009 deg
  • A4: \theta_H = 0.445 deg, \theta_V = 0.000 deg
  • A5: \theta_H = 0.448 deg, \theta_V = 0.014 deg

 

Attachment 1: autocollimator_wedge_measurement.pdf
autocollimator_wedge_measurement.pdf
  60   Wed Feb 6 02:34:10 2013 KojiOpticsCharacterizationWedge measurement with the autocollimator and the rotation stage

Measurement:

  • A6:   α = 0.665 deg, β = +3.0 arcmin (1.5 div up)
  • A7:   α = 0.635 deg, β =   0.0 arcmin (0.0 div up)
  • A8:   α = 0.623 deg, β = - 0.4 arcmin (-0.2 div up)
  • A9:   α = 0.670 deg, β = +2.4 arcmin (1.2 div up)
  • A10: α = 0.605 deg, β = +0.4 arcmin (0.2 div up)
  • A11: α = 0.640 deg, β = +0.8 arcmin (0.4 div up)
  • A12: α = 0.625 deg, β = - 0.6 arcmin (-0.3 div up)
  • A13: α = 0.630 deg, β = +2.2 arcmin (1.1 div up)
  • A14: α = 0.678 deg, β =   0.0 arcmin (0.0 div up)
  • B1:   α = 0.665 deg, β = +0.6 arcmin (0.3 div up)
  • B2:   α = 0.615 deg, β = +0.2 arcmin (0.1 div up)
  • B3:   α = 0.620 deg, β = +0.9 arcmin (0.45 div up)
  • B4:   α = 0.595 deg, β = +2.4 arcmin (1.2 div up)
  • B5:   α = 0.635 deg, β = - 1.8 arcmin (-0.9 div up)
  • B6:   α = 0.640 deg, β = +1.6 arcmin (0.8 div up)
  • B7:   α = 0.655 deg, β = +2.5 arcmin (1.25 div up)
  • B8:   α = 0.630 deg, β = +2.8 arcmin (1.4 div up)
  • B9:   α = 0.620 deg, β = - 4.0 arcmin (-2.0 div up)
  • B10: α = 0.620 deg, β = +1.2 arcmin (0.6 div up)
  • B11: α = 0.675 deg, β = +3.5 arcmin (1.75 div up)
  • B12: α = 0.640 deg, β = +0.2 arcmin (0.1 div up)

Analysis:

  • \theta_H = ArcSin[Sin(α) * n]
  • \theta_V = ArcSin[Sin(β) / n]/2
     
  • A6:   \theta_H = 0.490 deg, \theta_V =  0.017 deg
  • A7:   \theta_H = 0.534 deg, \theta_V =  0.000 deg
  • A8:   \theta_H = 0.551 deg, \theta_V = -0.0023 deg
  • A9:   \theta_H = 0.482 deg, \theta_V =  0.014 deg
  • A10: \theta_H = 0.577 deg, \theta_V =  0.0023 deg
  • A11: \theta_H = 0.526 deg, \theta_V =  0.0046 deg
  • A12: \theta_H = 0.548 deg, \theta_V = -0.0034 deg
  • A13: \theta_H = 0.541 deg, \theta_V =  0.013 deg
  • A14: \theta_H = 0.471 deg, \theta_V =  0.000 deg
  • B1:   \theta_H = 0.490 deg, \theta_V =  0.0034 deg
  • B2:   \theta_H = 0.563 deg, \theta_V =  0.0011 deg
  • B3:   \theta_H = 0.556 deg, \theta_V =  0.0051 deg
  • B4:   \theta_H = 0.592 deg, \theta_V =  0.014 deg
  • B5:   \theta_H = 0.534 deg, \theta_V = -0.010 deg
  • B6:   \theta_H = 0.526 deg, \theta_V =  0.0091 deg
  • B7:   \theta_H = 0.504 deg, \theta_V =  0.014 deg
  • B8:   \theta_H = 0.541 deg, \theta_V =  0.016 deg
  • B9:   \theta_H = 0.556 deg, \theta_V = -0.023 deg
  • B10: \theta_H = 0.556 deg, \theta_V =  0.0068 deg
  • B11: \theta_H = 0.475 deg, \theta_V =  0.020 deg
  • B12: \theta_H = 0.526 deg, \theta_V =  0.0011 deg

Quote:

Measurement:

  • A1: α = 0.68 deg, β = 0 arcmin (0 div)
  • A2: α = 0.80 deg, β = -6 arcmin (3 div down)
  • A3: α = 0.635 deg, β = -1.6 arcmin (0.8 div down)
  • A4: α = 0.650 deg, β = 0 arcmin (0div)
  • A5: α = 0.655 deg, β = +2.4 arcmin (1.2 div up)

Analysis:

  • \theta_H = ArcSin[Sin(α)*n]
  • \theta_V = ArcSin[Sin(β) / n]/2
     
  • A1: \theta_H = 0.465 deg, \theta_V = 0.000 deg
  • A2: \theta_H = 0.547 deg, \theta_V = -0.034 deg
  • A3: \theta_H = 0.434 deg, \theta_V = -0.009 deg
  • A4: \theta_H = 0.445 deg, \theta_V = 0.000 deg
  • A5: \theta_H = 0.448 deg, \theta_V = 0.014 deg

 

  62   Thu Feb 7 23:01:45 2013 KojiOpticsCharacterizationUV epoxy gluing test

 [Jeff, Yuta, Koji]

Gluing test with UV-cure epoxy Optocast 3553-LV-UTF-HM

- This glue was bought in the end of October (~3.5 months ago).

- The glue was taken out from the freezer at 1:20pm.
- Al sheet was laid on the optical table. We made a boat with Al foil and pour the glue in it (@1:57pm)
- We brought two kinds of Cu wires from the 40m. The thicker one has the diameter of 1.62mm.
The thinner one has the diameter of 0.62mm. We decided to use thinner one being cut into 50mm in length.

- The OMC glass prisms have the footprint of 10mmx20mm = 200mm^2. We tested several combinations
of the substrates. Pairs of mirrors with 1/2" mm in dia. (127mm) and a pair of mirrors with 20mm in dia. (314mm).

- Firstly, a pair of 1/2" mirrors made of SF2 glass was used. A small dub on a thinner Cu wire was deposited on a mirror.
  We illuminated the glue for ~10sec. When the surfaces of the pair was matched, the glue did not spread on the entire
  surface. The glue was entirely spread once the pressure is applied by a finger. Glue was cured at 2:15pm. 12.873mm
  thickness after the gluing.

Some remark:
1. We should be careful not to shine the glue pot by the UV illuminator.
2. The gluing surface should be drag wiped to remove dusts on the surface.

- Secondly, we moved onto 20mm mirror pair taken from the remnant of the previous gluing test by the eLIGO people.
This time about 1.5 times more glue was applied.

- The third trial is to insert small piece of alminum foil to form a wedge. The thickness of the foil is 0.041mm.
The glue was applied to the pair of SF2 mirror (1/2" in dia.). A small dub (~1mm in dia) of the glue was applied.
The glue filled the wedge without any bubble although the glue tried to slide out the foil piece from the wedge.
So the handling was a bit difficult. After the gluing we measured the thickness of the wedge by a micrometer gauge.
The skinny side was 12.837mm, and the thicker side was 12.885mm. This is to be compared with the total thickness
12.823mm before the gluing. The wedge angle is 3.8mrad (0.22deg). The glue dub was applied at 2:43, and the UV
illumination was applied at 2:46.

- At the end we glued a pair of fused silica mirrors. The total thickness before the gluing was 12.658 mm.
The glue was applied at 2:59pm. The thickness after the gluing is 12.663 mm.
This indicates the glue thickess is 5um.

  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
  64   Wed Feb 27 18:18:48 2013 KojiOpticsConfigurationMore perpendicularity test

Mounting Prisms:
(criteria: 30arcsec = 145urad => 0.36mm spot shift)
SN  Meas.(div) ArcSec Spec.
10   0.3989    11.97   29    good
11   0.2202     6.60   16
    good
16   0.1907     5.72    5
    good
20  -0.591    -17.73    5
    good
21  -2.378    -71.34   15

21  -1.7      -51.     15
01  -0.5      -15.     52
02  -2.5      -75.     48
06  -1.0      -30.     15
    good
07   1.7       51.     59
12  -2.2      -66.     40
13  -0.3      - 9.     12
    good
14  -2.8      -84.     27
15  -2.5      -75.     50
17   0.7       21.     48
22   2.9       87.    
63

Mirror A:
A1  -0.5      -15.     NA    good
A3   0.5       15.     NA
    good
A4   0.9       27.     NA
    good
A5   0.4       12.     NA
    good
A6   0.1        3.
    NA    good
A7   0.0        0.
    NA    good
A8   0.0       
0.     NA    good
A9   0.0       
0.     NA    good
A10  1.0      
30.     NA    good
A11  0.3       
9.     NA    good
A12  0.1       
3.     NA    good
A13  0.0       
0.     NA    good
A14  0.6      
18.     NA    good

Mirror B:
B1  -0.9     
-27.     NA    good
B2  -0.6     
-18.     NA    good
B3  -0.9     
-27.     NA    good
B4   0.7      
21.     NA    good
B5  -1.1     
-33.     NA
B6  -0.6     
-18.     NA    good
B7  -1.8     
-54.     NA
B8  -1.1     
-33.     NA
B9   1.8      
54.     NA
B10  1.2       
36.     NA   
B11 -1.7     
-51.     NA
B12  1.1       
33.     NA

  65   Fri Mar 1 23:06:15 2013 KojiOpticsConfigurationMore perpendicularity test final

Perpendicularity of the "E" mirror was measured.


Mounting Prisms:
(criteria: 30arcsec = 145urad => 0.36mm spot shift)
SN  Meas.(div) ArcSec Spec.
10   0.3989    11.97   29    good
11   0.2202     6.60   16
    good
16   0.1907     5.72    5
    good
20  -0.591    -17.73    5
    good
21  -2.378    -71.34   15

21  -1.7      -51.     15
01  -0.5      -15.     52
02  -2.5      -75.     48
06  -1.0      -30.     15
    good
07   1.7       51.     59
12  -2.2      -66.     40
13  -0.3      - 9.     12
    good
14  -2.8      -84.     27
15  -2.5      -75.     50
17   0.7       21.     48
22   2.9       87.    
63

Mirror A:
A1  -0.5      -15.     NA    good
A3   0.5       15.     NA
    good
A4   0.9       27.     NA
    good
A5   0.4       12.     NA
    good
A6   0.1        3.
    NA    good
A7   0.0        0.
    NA    good
A8   0.0       
0.     NA    good
A9   0.0       
0.     NA    good
A10  1.0      
30.     NA    good
A11  0.3       
9.     NA    good
A12  0.1       
3.     NA    good
A13  0.0       
0.     NA    good
A14  0.6      
18.     NA    good

Mirror B:
B1  -0.9     
-27.     NA    good
B2  -0.6     
-18.     NA    good
B3  -0.9     
-27.     NA    good
B4   0.7      
21.     NA    good
B5  -1.1     
-33.     NA
B6  -0.6     
-18.     NA    good
B7  -1.8     
-54.     NA
B8  -1.1     
-33.     NA
B9   1.8      
54.     NA
B10  1.2       
36.     NA   
B11 -1.7     
-51.     NA
B12  1.1       
33.     NA

Mirror E:
E1  -0.8      -24.     NA    good
E2  -0.8      -24.    
NA    good
E3  -0.25     - 7.5   
NA    good
E4  -0.5      -15.     NA
    good
E5   0.8       24.     NA    good
E6  -1.0      -30.     NA
    good
E7  -0.2      - 6.     NA
    good
E8  -0.8      -24.     NA
    good
E9  -1.0      -30.     NA
    good
E10  0.0        0.     NA
    good
E11 -1.0      -30.     NA
    good
E12 -0.3      - 9.     NA
    good
E13 -0.8      -24.     NA
    good
E14 -1.0      -30.     NA    good
E15 -1.2      -36.     NA

E16 -0.7      -21.     NA
    good
E17 -0.8      -24.     NA
    good
E18 -1.0      -30.     NA
    good

  66   Fri Mar 1 23:52:18 2013 KojiOpticsCharacterizationWedge measurement with the autocollimator and the rotation stage

Measurement:

  • E1:   α = 0.672 deg, β = +0.0 arcmin (0 div up)
  • E2:   α = 0.631 deg, β = - 0.3 arcmin (-0.15 div down)
  • E3:   α = 0.642 deg, β = +0.0 arcmin (0 div up)
  • E4:   α = 0.659 deg, β = +1.4 arcmin (0.7 div up)
  • E5:   α = 0.695 deg, β = +0.5 arcmin (0.5 div up)
  • E6:   α = 0.665 deg, β = - 0.4 arcmin (-0.2 div down)
  • E7:   α = 0.652 deg, β = +1.0 arcmin (0.5 div up)
  • E8:   α = 0.675 deg, β = +2.0 arcmin (1.0 div up)
  • E9:   α = 0.645 deg, β = - 2.4 arcmin (-1.2 div down)
  • E10: α = 0.640 deg, β = +2.2 arcmin (1.1 div up)
  • E11: α = 0.638 deg, β = +1.6 arcmin (0.8 div up)
  • E12: α = 0.660 deg, β = +1.6 arcmin (0.8 div up)
  • E13: α = 0.638 deg, β = +0.8 arcmin (0.4 div up)
  • E14: α = 0.655 deg, β = +0.4 arcmin (0.2 div up)
  • E15: α = 0.640 deg, β = +1.4 arcmin (0.7 div up)
  • E16: α = 0.655 deg, β = +0.6 arcmin (0.3 div up)
  • E17: α = 0.650 deg, β = +0.8 arcmin (0.4 div up)
  • E18: α = 0.640 deg, β = +2.4 arcmin (1.2 div up)

Analysis:

  • \theta_H = ArcSin[Sin(α) / n]
  • \theta_V = ArcSin[Sin(β) / n]/2
     
  • E1:   \theta_H = 0.460 deg, \theta_V =   0.000 deg
  • E2:   \theta_H = 0.432 deg, \theta_V =  -0.0034 deg
  • E3:   \theta_H = 0.439 deg, \theta_V =   0.000 deg
  • E4:   \theta_H = 0.451 deg, \theta_V =  0.016 deg
  • E5:   \theta_H = 0.475 deg, \theta_V =  0.011 deg
  • E6:   \theta_H = 0.455 deg, \theta_V =  -0.0046 deg
  • E7:   \theta_H = 0.446 deg, \theta_V =  0.011 deg
  • E8:   \theta_H = 0.462 deg, \theta_V =  0.023 deg
  • E9:   \theta_H = 0.441 deg, \theta_V =  -0.027 deg
  • E10:   \theta_H = 0.438 deg, \theta_V = 0.025 deg
  • E11:   \theta_H = 0.436 deg, \theta_V = 0.018 deg
  • E12:   \theta_H = 0.451 deg, \theta_V = 0.018 deg
  • E13:   \theta_H = 0.436 deg, \theta_V = 0.0091 deg
  • E14:   \theta_H = 0.448 deg, \theta_V = 0.0046 deg
  • E15:   \theta_H = 0.438 deg, \theta_V = 0.016 deg
  • E16:   \theta_H = 0.448 deg, \theta_V = 0.0068 deg
  • E17:   \theta_H = 0.444 deg, \theta_V = 0.0091 deg
  • E18:   \theta_H = 0.438 deg, \theta_V = 0.027 deg
  67   Tue Mar 5 19:37:00 2013 ZachOpticsCharacterizationeLIGO OMC visibility vs. power measurement details

EDIT (ZK): Koji points out that (1 - Ti) should really be the non-resonant reflectivity of the aligned cavity, which is much closer to 1. However, it should *actually* be the non-resonant reflectivity of the entire OMC assembly, including the steering mirror (see bottom of post). The steering mirror has T ~ 0.3%, so the true results are somewhere between my numbers and those with (1 - Ti) -> 1. In practice, though, these effects are swamped by the other errors.

More information about the power-dependent visibility measurement:

As a blanket statement, this measurement was done by exact analogy to those made by Sam and Sheon during S6 (c.f. LHO iLog 11/7/2011 and technical note T1100562), since it was supposed to be a verification that this effect still remains. There are absolutely better ways to do (i.e., ways that should give lower measurement error), and these should be investigated for our characterization. Obviously, I volunteer.

All measurements were made by reading the output voltages produced by photodetectors at the REFL and TRANS ports. The REFL PD is a BBPD (DC output), and the TRANS is a PDA255. Both these PDs were calibrated using a Thorlabs power meter (Controller: PM100D; Head: S12XC series photodiode-based---not sure if X = 0,2... Si or Ge) at the lowest and highest power settings, and these results agreed to the few-percent level. This can be a major source of error.

The power was adjusted using the HWP/PBS combination towards the beginning of the experiment. For reference, an early layout of the test setup can be seen in LLO:5978 (though, as mentioned above, the REFL and TRANS PDs have been replaced since then---see LLO:5994). This may or may not be a "clean" way to change the power, but the analysis should take the effect of junk light into account.

eOMC_visibility_3_4_13.png

Below is an explanation of the three traces in the plot. First:

  • TRANS: TRANS signal calibrated to W
  • REFL_UL: REFL signal while cavity is unlocked, calibrated to W
  • REFL_L: REFL signal while cavity is locked, calibrated to W
  • Psb: Sideband power (relative to carrier)
  • Ti: Input mirror transmission (in power)

Now, the traces

  1. Raw transmission: This measurement is simple. It is just the raw throughput of the cavity, corrected for the power in the sidebands which should not get through. I had the "AM_REF" PD, which could serve as an input power monitor, but I thought it was better to just use REFL_UL as the input power monitor and not introduce the error of another PD. This means I must also correct for the reduction in the apparent input power as measured at the REFL PD due to the finite transmission of the input coupler. This was not reported by Sam and Sheon, but can be directly inferred from their data.
    • trans_raw = TRANS ./ ( REFL_UL * (1 - Psb) * (1 - Ti) )
    • Equivalently, trans_raw = (transmitted power) ./ (input power in carrier mode)
  2. Coupling: This is how much of the power incident on the cavity gets coupled into the cavity (whether it ends up in transmission or at a loss port). Sheon plots something like (1 - coupling) in his reply to the above-linked iLog post on 11/8/2011.
    • coupling = ( REFL_UL * (1 - Ti) - REFL_L ) ./ ( REFL_UL * (1 - Psb) * (1 - Ti) )
    • Equivalently, coupling = [ (total input power) - (total reflected power on resonance) ] ./ (input power in carrier mode)
  3. Visibility: How much of the light that is coupled into the cavity is emerging from the transmitted port? This is what Sam and Sheon call "throughput" or "transmission" and is what is reported in the majority of their plots.
    • visibility = TRANS ./ ( REFL_UL * (1 - Ti) - REFL_L )
    • Equivalently, visibility = (transmitted power) ./ [ (total input power) - (total reflected power on resonance) ]
    • Also equivalently, visibility = trans_raw ./ coupling

The error bars in the measurement were dominated, roughly equally, by 1) systematic error from calibration of the PDs with the power meter, and 2) error from noise in the REFL_L measurement (since the absolute AC noise level in TRANS and REFL_L is the same, and TRANS >> REFL_L, the SNR of the latter is worse).

(1) can be helped by making ALL measurements with a single device. I recommend using something precise and portable like the power meter to make measurements at all the necessary ports. For REFL_L/UL, we can place a beam splitter before the REFL PD, and---after calibrating for the T of this splitter very well using the same power meter---both states can be measured at this port.

(2) can probably be helped by taking longer averaging, though at some point we run into the stability of the power setting itself. Something like 30-60s should be enough to remove the effects of the REFL_L noise, which is concentrated in the few-Hz region in the LLO setup.

One more thing I forgot was the finite transmission of the steering mirror at the OMC input (the transmission of this mirror goes to the QPDs). This will add a fixed error of 0.3%, and I will take it into account in the future.

  68   Wed Mar 6 23:24:58 2013 ZachOpticsCharacterizationeLIGO OMC visibility vs. power measurement details

I found that, in fact, I had lowered the modulation depth since when I measured it to be 0.45 rads --> Psb = 0.1.

Here is the sweep measurement:

TEK00005.PNG TEK00007.PNG

This is Psb = 0.06 --> gamma = 0.35 rads.

This changes the "raw transmission" and "coupling", but not the inferred visibility:

eOMC_visibility_3_4_13.png

I also measured the cavity AMTF at three powers today: 0.5 mW, 10 mW, and 45 mW input.

eOMC_AMTF_vs_power_3_6_13.png

They look about the same. If anything, the cavity pole seems slightly lower with the higher power, which is counterintuitive. The expected shift is very small (~10%), since the decay rate is still totally dominated by the mirror transmissions even for the supposed high-loss state (Sam and Sheon estimated the roundtrip loss at high power to be ~1400 ppm, while the combined coupling mirrors' T is 1.6%). I have not been able to fit the cavity poles consistently to within this kind of error.

  74   Wed Mar 20 09:38:02 2013 ZachOpticsCharacterization[LLO] OMC test bench modified

 For various reasons, I had to switch NPROs (from the LightWave 126 to the Innolight Prometheus).

I installed the laser, realigned the polarization and modulation optics, and then began launching the beam into the fiber, though I have not coupled any light yet.

A diagram is below. Since I do not yet have the AOM, I have shown that future path with a dotted line. Since we will not need to make AMTFs and have a subcarrier at the same time, I have chosen to overload the function of the PBS using the HWP after the AEOM. We will operate in one of two modes:

  1. AMTF mode: The AOM path is used as a beam dump for the amplitude modulation setup. A razor dump should physically be placed somewhere in the AOM path.
  2. Subcarrier mode: The AEOM is turned off and the HWP after it is used to adjust the carrier/subcarrier power ratio. I chose a 70T / 30R beamsplitter for the recombining, since we want to be able to provide ~100 mW with the carrier for transmission testing, and we don't need a particularly strong subcarrier beam for probing.

new_setup_traced.jpg

One thing that concerns me slightly: the Prometheus is a dual-output (1064nm/532nm) laser, with separate ports for each. I have blocked and locked out the green path physically, but there is some residual green light visible in the IR output. Since we are planning to do the OMC transmission testing with a Si-based Thorlabs power meter---which is more sensitive to green than IR---I am somewhat worried about the ensuing systematics. I *think* we can minimize the effect by detuning the doubling crystal temperature, but this remains to be verified.

 EDIT (ZK): Valera says there should be a dichroic beam splitter in the lab that I can borrow. This should be enough to selectively suppress the green.

  76   Sat Mar 23 02:41:00 2013 KojiOpticsGeneralBlack glass beam dumps for the first OMC

Received black glass beam dumps from MIT

- gluing by EP30-2 looks pretty fine. Enough sturdy.

- some gap visible between the glass => incident angle should be considered so that the first beam does not exit from the gap

- Dusts are visible on the glass surface. Some have a lot, the other have less. But every piece still needs to be wiped.

Attachment 1: P3223314.JPG
P3223314.JPG
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P3223319.jpg
Attachment 3: P3223320.jpg
P3223320.jpg
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