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ID Date Author Type Category Subjectup
  13   Tue Jul 31 21:33:17 2012 KojiGeneralGeneralPlan Update: August [!]

Completed work of the previous months: [Jul] [Aug] [Sep] [Oct] [Nov] [Dec]


Facility/Supplies

  • Work done
  • Things ordered
    • Office Depot
      • [delivered] Office Depot(R) Brand Stretch Wrap Film, 20 x 1000 Roll, Clear / 445013
      • [delivered] Eveready(R) Gold AA Alkaline Batteries, Pack Of 24 / 158448
      • [delivered] Rubbermaid(R) Roller Sponge Mop / 921841
      • [delivered] Rubbermaid(R) Roller Sponge Mop Replacement / 921858
      • [delivered] Rubbermaid(R) Sanitizing Caddy, 10 Quarts, Yellow / 674125
      • [delivered] Glad(R) Tall Kitchen Trash Bags, 13 Gallon, White, Box Of 28 / 269268
    • Global Industrial Equipment
      • [delivered] Extended Surface Pleated Cartridge Filter Serva-Cell Mp4 Slmp295 12X24X2 Gl    WBB431699
    • Global Industrial Equipment
      • [delivered] Nexel Poly-Z-Brite Wire Shelving 30"W x 21"D x 63"H Nexel Poly-Z-Brite™ Wire Shelving Starter Unit WB189209
      • [delivered] Stem Casters Set of (4) 5" Polyurethane Wheel, 2 With Brakes 1200 lb. Capacity WB500592    
    • Rack Solutions
      • [delivered] Open Frame Server Racks
        1 x 20" Depth Kit (Ideal for Audio/Video or Networking Racks) P/N: 111-1779
        1 x 36U, Rack-111 Post Kit P/N: 111-1728
        1 x Caster Kit for Open Frame RACK-111 P/N: 111-1731
      • [delivered] 36U Side Panel Kit $199.99 P/N: 102-1775
    • Rack shelf
      • [delivered] 1 RMS 19 X 15 SINGLE SIDED NON-VENTED SHELF 70121637
    • Work bench, Stools
      • [not yet] 72"L X 30"W Production Bench - Phenolic Resin Square Edge-Blue Form attached WB237381LBL    
      • [not yet] 72"W Lower Shelf For Bench - 15"D- Blue Form attached WB606951    
      • [not yet] ESD-Safe Vinyl Clean Room Stool with Nylon Base with Drag Chain Blue Form attached WBB560852    
    • P Touch
      • [delivered] Brother PT-2030 Desktop Office Labeler Punch-out product 672828    
      • [delivered] Brother(R) TZe-241 Black-On-White Tape, 0.75 x 26.2 Punch-out product 239384    
      • [delivered] Brother(R) TZe-231 Black-On-White Tape, 0.5 x 26.2 Punch-out product 239400    
    • UV light guide
      • [delivered] Fiber Optic Single Light Guide 5mm OD X 3mm ID X 1M L Note: This light guide can be used with MKIII UV Cure unit. OLB1081
    • Gloves (7.5, 8.0)
      • [delivered] GLOVE ACCTCH NR-LTX SZ7.5 PK25 Punch-out product 79999-306
      • [delivered] GLOVE ACCTCH NR-LTX SZ8 PK25 Punch-out product 79999-308
    • Lab coat (L,XL), Sticky Mat, Shoe Covers (L, XL), Cap, Mask
      • [delivered] LAB XP WH EL WR.COLL. NP L30EA Punch-out product 82007-618
      • [delivered] LAB XPWH EL WR.COLL. NP XL30EA Punch-out product 82007-620    
      • [delivered] VWR MAT ADHESIVE 30L 18X36 BLU Punch-out product 21924-110 (This was too small)
      • [delivered] VWR SHOECVR NSKID AP 2XL 150PR Punch-out product 414004-651    
      • [delivered] VWR SHOECVR NSKID AP XL 150PR Punch-out product 414004-650    
      • [delivered] CAP BOUFFANT 24IN RAYON CS500 Punch-out product 10843-053    
      • [delivered] MASK VLTC TIES N/STRL PK50 Punch-out product 10869-020
    • VWR
      • [delivered] FACE SHIELD UVC-803 Supplier: UVP 33007-151
         
    • [Delivered] Laser safety glasses
  • Work in progress

    •  
  • Work to be done
    • Replacing a file cabinet next to the south wall by a lockable cabinet
    • Laser sign
    • Safety glass holder/rack/shelf
    • Prepare clean supplies ~ glove 8.5,9,9.5
    • Ion gun safety issues: https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=88631
        
  • Design
    • Optical layout - Laser SOP
    • Additional HEPA stage
       
  • Test
    • Confirm particle level
       
  • Note: Optical Table W96" x D48" x H27"

Beaurocracy

  • Laser SOP
  • HV use?
  • UV?

Mechanics

  • Ongoing Work 
    • Cone-shaped wire clamp design (at the OMC end) - Jeff
       
  • Design
    • Wire preparation fixture - Jeff
    • How do we hold the PDs, QPDs, and black glass - we put 2 PDs and 2 QPDs on the PD mounting blacket. - Jeff
    • Integrated solidwork model - Derek
      • Q: How the wires are clamped at the top side?
      • Q: How much the length of the wire should be?
      • Q: Locations of the wire mounts on the plate
    • Cabling investigation:
      • Where do the cables from the feed-thrus anchored?
      • List of the current internal cables and their lengths
      • List of the required internal cables and their lengths
      • Can we route the intermediate stage of the suspension? Do we need new cables?
    • Dummy intermediate stage structure
       
    • Metal templates
      • First, decide an optical design
      • takes at least a month
         
    • Weights how heavy / how many
       
    • Earthquake stop design (Sam B)
       
  • Test
    • Cone-shaped wire clamp test - Jeff/Koji 
    • Balancing the plates
      • The Faraday isolator cage isn't clean
    • Dummy metal payload test at the sites???
       
  • Procedures to be decided
    • PZT alignment
    • Prototyping with metal parts?
    • UV glue? (heat) / gluing test
    • Balance

Optics

  • Things ordered
    • Newport LB servo
    • Halogen Lamp
    • N2 cylinder/lines/filter
  • Ongoing Work 
    • Mirrors to be delivered ~Aug
       
    • Design down select - Between "Single output & BS" vs "Two outputs & no BS"
    • Down selecting procedure:
      1. Assume ELIGO beam component
      2. Assume amount of 9MHz / 45MHz sidebands at the OMC input
      3. Calculate transmitted power
      4. Require HOM to be smaller than the TEM00 offset 
         
    • UV cured epoxy (Quate obtained)
  • Design
    • Mode design for HAM6 layout
    • Finalization of scattering paths
       
  • Tests
    • Measurement of PD angles
    • R&T of each mirror
    • Curvature of the curved mirrors
    • Cavity ref/trans/finesse
    • PD Q.E. & Reflectivity measurement vs incident angle
       
  • Things to be decided / confirmed
    • How to handle optics / assemblies (Talk to the prev people)
    • First contact? (Margot: applicable to a short Rc of ~2.5m)
    • Gluing templates to be designed (how to handle it?)
       
  • PDs
  • Misc
    • CCD beam analyzer (Zach: It is fixed.)
    • Are two PZTs used?
      • YES, for redundancy, range, upconversion tests.
         
  • Things to buy
  • Need to buy a fiber for mode cleaning?
  • Mode content of the ELIGO dark beam?
  • Jitter noise?
  • How to determine the design?
  • Why Fused Silica? (How much is the temp fluctuation in the chamber?)
  • How to align the cavity mirrors, input mirrors, QPDs, PDs, beam dumps.
  • PZTs @LLO
     

Electronics

  • Thorough scrutinization of cabling / wiring / electronics
    • ELIGO OMC Wiring diagram D070536-A2
      • Occupies 2 DB25s -> They were anchored on the sus cage
      • Preamps for DCPDs will be fixed on the ISI table
        -> DB25 for the DCPDs will be anchored on the table
      • Use longer thin cables for the DCPDs in order to route them through the suspension stages
      • Turn the heater cable to the one for the other PZT
  • Electronics / CDS electronics / software
  • Things to be tested
    • QPD/PD pre-selections (QE/noise)
    • PD preamp design (Rich)
    • Functionality test of QPD/PD/PZT

Shipping, storage etc


Jun/July
    - Lab renovation
Aug

    - Mechanics design
    - Mirror delivery
Sept

    - Basic optics test
    - Glue training
Oct
    - Cavity test
Nov

    - Suspending test
Dec
    - Shipping to LLO

Open questions
    Two optical designs
    Procedure
    Modeling
    Clamp design / stencil design
    gluing-installation procedure

  7   Sat Jul 14 02:16:07 2012 KojiGeneralGeneralPlan Update: July

Facility/Supplies

  • Work in progress
    • Floor cleaning
    • Plug slits on the roof of the HEPA booth - blanking panels have been ordered (Peter)
    • Install laser safety barrier (Peter is working on this)
    • Place a sticky mat
       
  • Work to be done
    • Replacing a file cabinet next to the south wall by a lockable cabinet
    • Replacing a lab desk at the west side of the room. (Vladimir's)
    • Replacing Vladimir's rack with nicer one.
    • Laser sign
    • Safety glass holder
    • Prepare clean supplies (Shoes/Coverall/Hats/Gloves) => go to VWR stock room
      • glove 8.5,9,9.5
         
    • Label maker (P-Touch) & Tape
        
  • Design
    • Optical layout - Laser SOP
    • Additional HEPA stage
       
  • Test
    • Confirm particle level
       
  • Note: Optical Table W96" x D48" x H27"

Beaurocracy

  • Laser SOP
  • HV use?
  • UV?

Mechanics

  • Ongoing Work 
    • Cone-shaped wire clamp design (at the OMC end) - Jeff
       
  • Design
    • Wire preparation fixture - Jeff
    • How do we hold the PDs, QPDs, and black glass - we put 2 PDs and 2 QPDs on the PD mounting blacket. - Jeff
    • Integrated solidwork model - Sam
      • Q: How the wires are clamped at the top side?
      • Q: How much the length of the wire should be?
      • Q: Locations of the wire mounts on the plate
    • Cabling investigation:
      • Where do the cables from the feed-thrus anchored? - Sam
      • List of the current internal cables and their lengths - Sam
      • List of the required internal cables and their lengths
      • Can we route the intermediate stage of the suspension? Do we need new cables?
    • Dummy intermediate stage structure
       
    • Metal templates
      • First, decide an optical design
      • takes at least a month
         
    • Weights how heavy / how many
       
  • Test
    • Cone-shaped wire clamp test - Jeff/Koji 
    • Balancing the plates
      • The Faraday isolator cage isn't clean
    • Dummy metal payload test at the sites???
       
  • Procedures to be decided
    • PZT alignment
    • Prototyping with metal parts?
    • UV glue? (heat) / gluing test
    • Balance

Optics

  • Ongoing Work 
    • Mirrors to be delivered ~Aug
       
    • Design down select - Between "Single output & BS" vs "Two outputs & no BS"
    • Down selecting procedure:
      1. Assume ELIGO beam component
      2. Assume amount of 9MHz / 45MHz sidebands at the OMC input
      3. Calculate transmitted power
      4. Require HOM to be smaller than the TEM00 offset 
         
    • UV cured epoxy (Quate obtained)
  • Design
    • Mode design for HAM6 layout
    • Finalization of scattering paths
       
  • Tests
    • Measurement of PD angles
    • R&T of each mirror
    • Curvature of the curved mirrors
    • Cavity ref/trans/finesse
    • PD Q.E. & Reflectivity measurement vs incident angle
       
  • Things to be decided / confirmed
    • How to handle optics / assemblies (Talk to the prev people)
    • First contact? (Margot: applicable to a short Rc of ~2.5m)
    • Gluing templates to be designed (how to handle it?)
       
  • PDs
  • Misc
    • CCD beam analyzer (Zach: It is fixed.)
    • Are two PZTs used?
      • YES, for redundancy, range, upconversion tests.
         
  • Things to buy
  • Need to buy a fiber for mode cleaning?
  • Mode content of the ELIGO dark beam?
  • Jitter noise?
  • How to determine the design?
  • Why Fused Silica? (How much is the temp fluctuation in the chamber?)
  • How to align the cavity mirrors, input mirrors, QPDs, PDs, beam dumps.
     

Electronics

  • Thorough scrutinization of cabling / wiring / electronics
  • Electronics / CDS electronics / software
  • Things to be tested
    • QPD/PD pre-selections (QE/noise)
    • Functionality test of QPD/PD/PZT

Shipping, storage etc


Jun/July
    - Lab renovtion
    - Mechanics design
    - Glue training
Aug
    - Mirror delivery
    - Basic optics test
Sept
    - Cavity test
    - Suspending test
NOV~DEC
    - Shipping to LLO

Open questions
    Two optical designs
    Procedure
    Modeling
    Clamp design / stencil design
    gluing-installation procedure

 


July:Facility/Supplies

  34   Wed Nov 7 20:44:11 2012 KojiGeneralGeneralPlan Update: November [!]

Completed work of the previous months: [Jul] [Aug] [Sep] [Oct] [Nov] [Dec]


  • Work done
    • Wedge measurement (1st trial) [ELOG]
    • RoC measurement [ELOG]
  • Work in progress
    • R&T measurement
    • Wedge measurement
  • Work to be done
    • QPD/PD pre-selections (QE/noise)
    •  
    •  
    •  
    • Misc. / Beaurocracy?
      • Continuous monitoring of the particle level
      • Replacing a file cabinet next to the south wall by a lockable cabinet
      • Ion gun safety issues: https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=88631
      • Laser SOP / HV use? / UV?
  • Things delivered
  • Things ordered
    • Power strips Tripp Lite PS3612 (Ordered Nov. 8, Delivered Nov. 12)
    • Kapton tapes (1in x 6, 1/2in x 12 Delivered Nov. 15)
    • Sticky Mats (VWR 18888-216 Delivered Nov. 12 and 21992-042)
    • Duck tape (PK3) (Delivered Nov. 12)
    • Wipers 12"x12" 2ply x 119 pairs x case15 (Delivered Nov. 12)
    • Syringes (1mL&2mL) & Needles (20G x dozen)
    • Stainless trays with cover (Steve Delivered Nov. 12)
    • Gold Plated allen keys (Steve Delivered Nov. 12)
    • Forceps (Delivered Nov. 12) / Tweezers / Scissors (Delivered Nov. 12)
  • Things to buy / get
    • OMC testing optics / opto-mechanics
    • Black Glass / Black Glass holder / AR ==> Some at the 40m, some from LLO
    • Ionized air blow
      • N2 or Air cylinder: 4N - UHP or 5N - Research Grade.  (... steal from Downs)
    • Clean tools, tray, storage
    • Supply
      • Additional clean supplies ~ glove 8.5,9,9.5
      • Stainless bats / Pure solvents (Metha / Aceton / Iso) / Syringes / Lint free cloth / Paper lens tissue
      • Lab coats
    • ATF
      • Tefron tape
      • Thorlabs 8-32 screw kit / Thorlabs HW-KIT1
      • Pedestal Shims - Newport
  • Things to be done
    • Cavity ref/trans/finesse
    • PD Q.E. & Reflectivity measurement vs incident angle
    • Functionality test of QPD/PD (PeterK) /PZT
       
  • Procedures to be decided
    • PZT alignment
    • UV glue? (heat) / gluing test
    • Balance
    • N2 cylinder/lines/filter
    • Shipping procedure: New shipping cage design on going (Jeff) => Plastic box similar to COC
  • Design
    • Solidworks raytracing model
    • Mode design for HAM6 layout
       
  • Things to be decided / confirmed
    • How to handle optics / assemblies (Talk to the prev people)
    • First contact? (Margot: applicable to a short Rc of ~2.5m)
    • Gluing templates to be designed (how to handle it?)
  • Jitter noise?
  • How to align the cavity mirrors, input mirrors, QPDs, PDs, beam dumps.

Electronics ==> Rich

  29   Tue Oct 16 15:51:01 2012 KojiGeneralGeneralPlan Update: October [!]

Completed work of the previous months: [Jul] [Aug] [Sep] [Oct] [Nov] [Dec]


Facility/Supplies

  • Work in progress
    • RoC measurement
    • R&T measurement
    • Wedge measurement
  • Work to be done
    • Replacing a file cabinet next to the south wall by a lockable cabinet
    • Additional clean supplies ~ glove 8.5,9,9.5
    • Stainless bats
    • Ion gun safety issues: https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=88631
        
  • Design
    • Laser SOP
       
  • Test
    • Continuous monitoring of the particle level
       
  • Note: Optical Table W96" x D48" x H27"

Beaurocracy

  • Laser SOP / HV use? / UV?
  • Procedures to be decided
    • PZT alignment
    • UV glue? (heat) / gluing test
    • Balance
    • N2 cylinder/lines/filter
  • Design
    • Mode design for HAM6 layout
    • Finalization of scattering paths
       
  • Things to be decided / confirmed
    • How to handle optics / assemblies (Talk to the prev people)
    • First contact? (Margot: applicable to a short Rc of ~2.5m)
    • Gluing templates to be designed (how to handle it?)
       
  • PDs
  • Things to buy
  • Need to buy a fiber for mode cleaning?
  • Mode content of the ELIGO dark beam?
  • Jitter noise?
  • How to determine the design?
  • Why Fused Silica? (How much is the temp fluctuation in the chamber?)
  • How to align the cavity mirrors, input mirrors, QPDs, PDs, beam dumps.
  • PZTs @LLO
     

Electronics

  • Thorough scrutinization of cabling / wiring / electronics
    • ELIGO OMC Wiring diagram D070536-A2
      • Occupies 2 DB25s -> They were anchored on the sus cage
      • Preamps for DCPDs will be fixed on the ISI table
        -> DB25 for the DCPDs will be anchored on the table
      • Use longer thin cables for the DCPDs in order to route them through the suspension stages
      • Turn the heater cable to the one for the other PZT
  • Electronics / CDS electronics / software
  • Things to be tested
    • QPD/PD pre-selections (QE/noise)
    • PD preamp design (Rich)
    • Functionality test of QPD/PD/PZT

Shipping, storage etc

  136   Mon Jun 3 21:19:03 2013 KojiGeneralGeneralPlanning

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

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

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

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

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

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

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

(Koji)
[done] - Room cleaning

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

Day 0
- Freight and Koji moving

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

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

Day 3
- Power dependence test

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

TBD

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

TBD

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

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

cf. previous documents: E080024, E1300201

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

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

 

  395   Thu Oct 8 19:55:22 2020 KojiGeneralCharacterizationPower Measurement of Mephisto 800NE 1166A

The output of Mephisto 800NE (former TNI laser) was measured.
The output power was measured with Thorlabs sensors (S401C and S144C). The reference output record on the chassis says the output was 837mW at 2.1A injection.
They all showed some discrepancy. Thus we say that the max output of this laser is 1.03W at 2.1A injection based on the largest number I saw.

  227   Wed Jul 22 09:43:01 2015 KojiElectronicsAM Stabilized EOM DriverPower supply test of the EOM/AOM Driver

Serial Number of the unit: S1500117
Tester: Koji Arai
Test Date: Jul 22, 2015

1) Verify the proper current draw with the output switch off:

+24 Volt current: 0.08 A Nom.
-24 Volt current: 0.07 A Nom.
+18 Volt current: 0.29 A Nom.
-18 Volt current: 0.24 A Nom.

2) Verify the proper current draw with the output switch on:
+24 Volt current: 0.53 A Nom.
-24 Volt current: 0.07 A Nom.
+18 Volt current: 0.21 A Nom.
-18  Volt current: 0.26 A Nom.

3) Verify the internal supply voltages:

All look good.

TP13 -5.001V
TP12 -15.00
TP11 -21.05
TP10 -10.00
TP5  -18.19
TP6  -24.22
TP2  +24.15
TP3  +18.22
TP9  + 9.99
TP17 +24.15
TP14 +21.04
TP15 +15.00
TP16 + 4.998

4) Verify supply OK logic:
All look good. This required re-disassembling of the PCBs...

Check then pin 5 on U1 (connected to R11) and U4 (connected to R23):

U1 3.68V (=Logic high)
U4 3.68V (=Logic high)

5) Verify the relays for the power supply sequencing: OK

Turn off +/-24 V. Confirm Pin 5 of K1 and K2 are not energized to +/-18V. => OK
Turn on +/-24 V again. Confirm Pin 5 of K1 and K2 are now energized to +/-18V. => OK

6) Verify noise levels of the internal power supply voltages:

TP13 (- 5V) 13nV/rtHz@140Hz
TP12 (-15V) 22
nV/rtHz@140Hz
TP11 (-21V) 32
nV/rtHz@140Hz
TP10 (-10V) 16nV/rtHz@140Hz
TP9  (+10V)  9
nV/rtHz@140Hz
TP14 (+21V) 21nV/rtHz@140Hz
TP15 (+15V) 13nV/rtHz@140Hz
TP16 (+ 5V) 11nV/rtHz@140Hz

 

Note that the input noise of SR785 is 9~10nV/rtHz@140Hz with -50dBbpk input (AC)

 

  399   Fri Nov 6 18:38:00 2020 KojiGeneralGeneralPowermeter lent from OMC Lab to 2um ECDL

Thorlabs' powermeter controler + S401C head was lent from OMC Lab.

https://nodus.ligo.caltech.edu:8081/SUS_Lab/1856

  290   Thu Nov 30 12:18:41 2017 StephenGeneralGeneralPreparation for Modal Testing on 4 December

Norna Robertson, Stephen Appert ||  29 Nov 2017, 2 pm to 4 pm  ||  227 Downs, CIT

We made some preparations for modal testing, but did not have enough time to make measurements. Below is an after-the-fact log, including some observations and photos of the current state of the OMC bench.

  1. Previous testing results at T1700471 (technical note in progress as of 30 Nov 2017).
    1. One goal of the next round: add damping material to equate with damping material of T1600494.
    2. Second goal of the next round: use a more localized sweep to better resolve the body mode around 1080 Hz -1100 Hz
  2. Transport Fixture was opened without issue, revealing the "Top" (suspending and cable routing) surface of the bench. Damping stacks were still in place from previous testing
  3. We removed the bolts from the damper stacks, but found that all masses with metal-viton interfaces had adhered to viton washers, causing the stacks to stick together.
    1. By using an allen key as a lever to wedge apart bottom mass and the bracket where they were joined by a viton washer, we separated the masses from the bracket.
    2. An allen key was used as a lever to push apart the two masses, which were also joined by a viton washer
    3. Once exposed, viton washers were pried from metal surfaces.
  4. After the damper stacks had been detached from the  No viton washer appeared to leave any residue or particulate - the separated parts all appeared as clean as they had been at the onset.
  288   Fri Sep 8 15:14:05 2017 KojiFacilityGeneralPreparation for the plumbing work

[Steve, Aaron, Koji]

We've finished the preparation for the forthcoming plumbing work on (nominally) Sept 16th Saturday.
We've covered most of the west side of the OMC lab with plastic sheets and wraps.

Some tips:

  • The plastic sheets Eric gave us were a bit too thin and pron to got torn. Thicker sheets are preferable.
  • The blue tape that Eric gave us was very useful.
  • The stretch wrap film, which I bought long time ago, was so useful. Office Depot "Office Depot(R) Brand Stretch Wrap Film, 20 x 1000 Roll, Clear" PN: 445013
  • We also used patches of Kitchen Trash Bags to cover some small opening of the large sheets. Office Depot "Glad(R) Tall Kitchen Trash Bags, 13 Gallon, White, Box Of 28" PN 269268
  264   Mon Aug 15 10:09:10 2016 KojiGeneralGeneralPrev H1 OMC shipped to CIT

Previous H1 OMC shipped from LHO to CIT

https://ics-redux.ligo-la.caltech.edu/JIRA/browse/Shipment-8196

  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

  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)

  258   Tue Apr 5 18:14:55 2016 KojiGeneralLoan / LendingQPD Lending Crackle

Xiaoyue

QPD head
X-Z stage
Mounting brackets
DB15 cable
QPD matrix circuit
+/-18V power supply cable

  132   Thu May 30 15:00:28 2013 KojiOpticsGeneralQPD alignment

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

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

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

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

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

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

Here are the raw numbers


QPD#            QPD1       QPD2
Diode#          #43        #38

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

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

  133   Fri May 31 05:46:54 2013 KojiOpticsGeneralQPD alignment

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

QPD1.JPG QPD2.JPG

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

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

QPD#              QPD1       QPD2
Diode#            #43        #38

-------------------------------------
Power Incident     84.7 uW   86.2 uW
Sum Out            56   mV   61   mV
Vertical Out       -6.8 mV   10   mV
Horizontal Out      4.2 mV    8.8 mV
SEG1              -17   mV  -15   mV
SEG2              -14.5 mV  -11   mV
SEG3              -11   mV  -15   mV
SEG4              -13   mV  -20   mV
-------------------------------------
Spot position X   +25   um  +46   um  (positive = more power on SEG1 and SEG4)
Spot position Y   -42   um  +46   um  (positive = more power on SEG3 and SEG4)
-------------------------------------

Responsivity[A/W] 0.66      0.71
Q.E.              0.77      0.82
-------------------------------------

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

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

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

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

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

  171   Tue Oct 15 18:50:08 2013 KojiOpticsCharacterizationQPD alignment

1) Deburr the bottom surfaces of the QPD housings

2) Aligned the QPDs

 

QPD#              QPD1       QPD2
Housing#          #004       #008
Diode#            #44        #46
Shim              1.75mm 001 1.25mm 001

-------------------------------------
Power Incident    125.7 uW  126.4 uW
Sum Out            80.1 mV   78.9 mV
Vertical Out      + 3.4 mV    0   mV
Horizontal Out    -23.7 mV  -26   mV
SEG1              -15.6 mV  -13.2 mV
SEG2              -13.1 mV  -13.3 mV
SEG3              -29.0 mV  -26.4 mV
SEG4              -23.2 mV  -26.3 mV
-------------------------------------
Spot position X   -13   um  - 0.8 um  (positive = more power on SEG1 and SEG4)
Spot position Y   +93   um +107   um  (positive = more power on SEG3 and SEG4)
-------------------------------------

Responsivity[A/W] 0.64      0.62
Q.E.              0.74      0.73
-------------------------------------

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

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

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

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

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

  115   Wed Apr 17 07:30:04 2013 KojiOpticsGeneralQPD path glued

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

- Check the alignment of the beam with the cavity.

- Placed the prisms

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

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

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

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

- FInally a glass bracket was glued.

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

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

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

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

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

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

- The dumps were glued.

  231   Mon Aug 10 02:11:47 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

This is an entry for the work on Aug 3rd.

LIGO DCC E1500151

Power supply check

- Removed the RF AM detector board and exposed the D0900848 power board. The board revision is Rev. A.

- The power supply voltage of +30.2V and -30.5V were connected as +/-31V supplies. These were the maximum I could produce with the bench power supply I had. +17.2V and -17.1V were supplied as +/-17V supplies.

- Voltage reference: The reference voltages were not +/-10V but +/-17V. The cause was tracked down to the voltage reference chip LT1021-10. It was found that the chip was mechanically destroyed (Attachment 1, the legs were cut by me) and unluckily producing +17V. The chip was removed from the board. Since I didn't have any spare LT1021-10, a 8pin DIP socket and an AD587 was used instead. Indeed AD587 has similar performance or even better in some aspects. This fixed the reference voltage.

- -5V supply: After the fix of the reference voltage, I still did not have correct the output voltage of -5V at TP12. It was found that the backpanel had some mechanical stress and caused a leg of the current boost transister cut and a peeling of the PCB pattern on the component lalyer (Attachment 2). I could find some spare of the transister at the 40m. The transister was replaced, and the pattern was fixed by a wire. This fixed the DC values of the power supply voltages. In fact, +/-24V pins had +/-23.7V. But this was as expected. (1+2.74k/2k)*10V = 23.7V .

- VREFP Oscillation: Similarly to the EOM/AOM driver power supply board (http://nodus.ligo.caltech.edu:8080/OMC_Lab/225), the buffer stage for the +10V has an oscillation at 762kHz with 400mVpp at VREFP. This was fixed by replacing C20 (100pF) with 1.2nF. The cap of 680pF was tried at first, but this was not enough to completely elliminate the oscilation.

- VREFN Oscillation: Then, similarly to the EOM/AOM driver power supply board (http://nodus.ligo.caltech.edu:8080/OMC_Lab/225), the amplifier and buffer stage for the -10V has an oscillation at 18MHz with 60mVpp at VREFN. This was fixed by soldering 100pF between pin6 and pin7 of U6.

- Voltage "OK" signal: Checked the voltage of pin5 of U1 and U4 (they are connected). Nominally the OK voltage had +2.78V. The OK voltage turned to "Low (~0V)" when:
The +31V were lowered below +27.5V.
The +31V were lowered below -25.2V.
The +17V were lowered below +15.2V.
The +17V were lowered below -15.4V.

- Current draw: The voltage and current supply on the bench top supplies are listed below

+30.2V 0.09A, -30.5V 0.08A, +17.2V 0.21A, -17.1V 0.10A

- Testpoint voltages:

TP12(-5V) -5.00V
TP11(-15) -14.99V
TP10(-24V) -23.69V
TP9(-10V) -9.99V
TP5(-17V) -17.15V
TP6(-31V) -30.69

TP2(+31V) +30.37V
TP3(+17V) +17.24V
TP8(+10V) +10.00V
TP16(+28V) +28.00V
TP13(+24V) +23.70V
TP14(+15V) +15.00V
TP15(+5V) +5.00V

 

  232   Mon Aug 10 11:39:40 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Entry for Aug 6th, 2015

I faced with difficulties to operate the RF AM detectors.

I tried to operate the RF AM detector. In short I could not as I could not remove the saturation of the MON outputs, no matter how jiggle the power select rotary switches. The input power was 10~15dBm.

D0900761 Rev.A
https://dcc.ligo.org/LIGO-D0900761-v1

I've measured the bias voltage at TP1. Is the bias such high? And does it show this inversion of the slope at high dBm settings?

Setting Vbias
 [dBm]   [V]

   0    21.4
   2    21.0
   4    20.5
   6    19.8
   8    18.8
  10    17.7
  12    16.3
  14    14.2
  16    11.9
  18    10.6
  20    11.8
  22    15.0


The SURF report (https://dcc.ligo.org/LIGO-T1000574) shows monotonic dependence of Vbias from 0.6V to 10V (That is supposed to be the half of the voltage at TP1). 
I wonder I need to reprogram FPGA?

But if this is the issue, the second detector should still work as it has the internal loop to adjust the bias by itself.
TP3 (Page 1 of D0900761 Rev.A) was railed. But still MON2 was saturated.
I didn't see TP2 was also railed. It was ~1V (not sure any more about the polarity). But TP2 should also railed.

Needs further investigation

  233   Mon Aug 10 11:57:17 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Spending some days to figure out how to program CPLD (Xilinx CoolRunner II XC2C384).

I learned that the JTAG cable which Daniel sent to me (Altium JTAG USB adapter) was not compatible with Xilinx ISE's iMPACT.

I need to use Altium to program the CPLD. However I'm stuck there. Altium recognizes the JTAG cable but does not see CPLD. (Attachment 1)

Upon the trials, I followed the instruction on awiki as Daniel suggested.
http://here https://awiki.ligo-wa.caltech.edu/aLIGO/TimingFpgaCode

Altium version is 15.1. Xilinx ISE Version is 14.7

  234   Mon Aug 10 12:09:49 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Still suffering from a power supply issue!

I have been tracking the issues I'm having with the RF AM detector board.

I found that the -5V test point did not show -5V but ~+5V! It seemed that this pin was not connected to -5V but was passive.

I removed the RF AM detector board and exposed the power board again. Pin 11 of P3 interboard connector indeed was not connected to TP12 (-5V). What the hell?

As seen in the attached photo, the PCB pattern for the Pin 11 is missing at the label "!?" and not driven. I soldered a piece of wire there and now Pin11 is at -5V.


This fix actually changed several things. Now the bias setting by the rotary switches works.

Setting BIAS1
 [dBm]   [V]

   0    0.585
   2    0.720
   4    0.897
   6    1.12
   8    1.42
  10    1.79
  12    2.25
  14    2.84
  16    3.60
  18    4.56
  20    5.75
  22    7.37

This allows me to elliminate the saturation of MON1 of the first RF AM detector. I can go ahead to the next step for the first channel.

Now the bias feedback of the second detector is also behaving better. Now TP2 is railing.

Still MON2 is saturated. So, the behavior of the peak detectors needs to be reviewed.

  238   Fri Aug 28 02:14:53 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151 ~ 37MHz OCXO AM measurement

In order to check the noise level of the RFAM detector, the power and cross spectra for the same signal source
were simultaneously measured with the two RFAM detectors.


As a signal source, 37MHz OCXO using a wenzel oscillator was used. The output from the signal source
was equaly splitted by a power splitter and fed to the RFAM detector CHB(Mon1) and CHA(Mon2).

The error signal for CHB (Mon1) were monitored by an oscilloscope to find an appropriate bias value.
The bias for CHA are adjusted automatically by the slow bias servo.

The spectra were measured with two different power settings:

Low Power setting: The signal source with 6+5dB attenuation was used. This yielded 10.3dBm at the each unit input.
The calibration of the low power setting is dBc = 20*log10(Vrms/108). (See previous elog entry)

High Power setting: The signal source was used without any attenuation. This yielded 22.4dBm at the each unit input.
The calibration for the high power setting was measured upon the measurement.
SR785 was set to have 1kHz sinusoidal output with the amplitude of 10mVpk and the offset of 4.1V.
This modulation signal was fed to DS345 at 30.2MHz with 24.00dBm
The network analyzer measured the carrier and sideband power levels
30.2MHz 21.865dBm
USB    -37.047dBm
LSB    -37.080dBm  ==> -58.9285 dBc (= 0.0011313)

The RF signal was fed to the input and the signal amplitude at Mon1 and Mon2 were measured
MON1 => 505   mVrms => 446.392 Vrms/ratio
MON2 => 505.7 mVrms => 447.011 Vrms/ratio
dBc = 20*log10(Vrms/446.5).


Using the cross specrum (or coherence)of the two signals, we can infer the noise level of the detector.

Suppose there are two time-series x(t) and y(t) that contain the same signal s(t) and independent but same size of noise n(t) and m(t)

x(t) = n(t) + s(t)
y(t) = m(t) + s(t)

Since n, m, s are not correlated, PSDs of x and y are

Pxx = Pnn + Pss
Pyy = Pmm+Pss = Pnn+Pss

The coherence between x(t) and y(t) is defined by

Cxy = |Pxy|^2/Pxx/Pyy = |Pxy|^2/Pxx^2

In fact |Pxy| = Pss. Therefore

sqrt(Cxy) = Pss/Pxx

What we want to know is Pnn

Pnn = Pxx - Pss = Pxx[1 - sqrt(Cxy)]
=> Snn = sqrt(Pnn) = Sxx * sqrt[1 - sqrt(Cxy)]

This is slightly different from the case where you don't have the noise in one of the time series (e.g. feedforward cancellation or bruco)


Measurement results

 

Power spectra:
Mon1 and Mon2 for both input power levels exhibited the same PSD between 10Hz to 1kHz. This basically supports that the calibration for the 22dBm input (at least relative to the calibration for 10dBm input) was corrected. Abobe 1kHz and below 10Hz, some reduction of the noise by the increase of the input power was observed. From the coherence analysis, the floor level for the 10dBm input was -178, -175, -155dBc/Hz at 1kHz, 100Hz, and 10Hz, respectively. For the 22dBm input, they are improved down to -188, -182, and -167dBc/Hz at 1kHz, 100Hz, and 10Hz, respectively.

 

  240   Tue Sep 8 10:55:31 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151 ~ 37MHz OCXO AM measurement

Test sheet: https://dcc.ligo.org/LIGO-E1400445

Test Result (S1500114): https://dcc.ligo.org/S1500114

  237   Fri Aug 28 01:08:14 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151 ~ Calibration

Worked on the calibration of the RF AM Measurement Unit.

The calibration concept is as follows:

  • Generate AM modulated RF output
  • Measure sideband amplitude using a network anayzer (HP4395A). This gives us the SSB carrier-sideband ratio in dBc.
  • Measure the output of the RF AM measurement unit with the same RF signal
  • Determine the relationship between dBc(SSB) and the output Vrms.

The AM modulated signal is produced using DS345 function generator. This FG allows us to modulate
the output by giving an external modulation signal from the rear panel. In the calibration, a 1kHz signal with
the DC offset of 3V was given as the external modulation source. The output frequency and output power of
DS345 was set to be 30.2MHz (maximum of the unit) and 14.6dBm. This actually imposed the output
power of 10.346dBm. Here is the result with the modulation amplitude varied

                 RF Power measured             Monitor output
Modulation       with HP4395A (dBm)           Measure with SR785 (mVrms)
1kHz (mVpk)   Carrier    USB      LSB          MON1       MON2
   0.5        9.841    -72.621  -73.325          8.832      8.800
   1          9.99     -65.89   -65.975         17.59      17.52
   2          9.948    -60.056  -59.747         35.26      35.07
   3          9.90     -56.278  -56.33          53.04      52.9
   5          9.906    -51.798  -51.797         88.83      88.57
  10          9.892    -45.823  -45.831        177.6      177.1
  20          9.870    -39.814  -39.823        355.3      354.4
  30          9.8574   -36.294  -36.307        532.1      531.1
  50          9.8698   -31.86   -31.867        886.8      885.2
 100          9.8735   -25.843  -25.847       1772       1769
 150          9.8734   -22.316  -22.32        2656       2652
 200          9.8665   -19.819  -19.826       3542       3539
 300          9.8744   -16.295  -16.301       5313       5308

The SSB carrier sideband ratio is derived by SSB[dBc] = (USB[dBm]+LSB[dBm])/2 - Carrier[dBm]

This measurement suggests that 10^(dBc/20) and Vrms has a linear relationship. (Attachment 1)
The data points were fitted by the function y= a x.

=> 10^dBc(SSB)/20 = 108*Vrms (@10.346dBm input)


Now we want to confirm this calibration.

DS345 @30.2MHz was modulated with the DC offset + random noise. The resulting AM modulated RF was checked with the network analyzer and the RFAM detector
in order to compare the calibrated dBc/Hz curves.

A) SR785 was set to produce random noise
B) Brought 2nd DS345 just to produce the DC offset of -2.52V (Offset display -1.26V)
Those two are added (A-B) by an SR560 (DC coupling, G=+1, 50 Ohm out).
The output was fed to Ext AM in DS345(#1)

DS345(#1) was set to 30.2MHz 16dBm => The measured output power was 10.3dBm.

On the network analyzer the carrier power at 30.2MHz was 9.89dBm

Measurement 1) SR785     1.6kHz span 30mV random noise (observed flat AM noise)
Measurement 2) SR785   12.8kHz span 100mV random noise (observed flat AM noise)
Measurement 3) SR785 102.4kHz span 300mV random noise (observed cut off of the AM modulation due to the BW of DS345)

The comparison plot is attached as Attachment 2. Note that those three measurements are independent and are not supposed to match each other.
The network analyzer result and RFAM measurement unit output should agree if the calibration is correct. In fact they do agree well.

 

  307   Wed Aug 29 11:06:30 2018 KojiGeneralGeneralRF AM RIN and dBc conversion

0. If you have an RF signal whose waveform is 1 \times \sin(2 \pi f t), the amplitude is constant and 1.

1. If the waveform [1+0.1 \sin(2 \pi f_{\rm m} t)] \sin(2 \pi f t), the amplitude has the DC value of 1 and AM with the amplitude of 0.1 (i.e. swing is from 0.9 to 1.1). Therefore the RMS RIN of this signal is 0.1/1/Sqrt(2).

2. The above waveform can be expanded by the exponentials.

\left[-\frac{1}{2} i e^{i\,2\,\pi f t} + 0.025 e^{i\,2\,\pi (f-f_{\rm m}) t}- 0.025 e^{i\,2\,\pi (f+f_{\rm m}) t} \right] - {\rm C.C.}

Therefore the sideband carrier ratio R is 0.025/0.5 = 0.05. This corresponds to 20 log10(0.05) = -26dBc


In total, we get the relationship of dBc and RIN as {\rm dBc} = 20 \log_{10}(\rm{RIN}/\sqrt{2}), or R = RIN/sqrt(2)

  228   Wed Jul 22 10:15:14 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

7) Make sure the on/off RF button works,
=> OK

8) Make sure the power output doesn't oscillate,

Connect the RF output to an oscilloscope (50Ohm)
=> RF output: there is no obvious oscillation

Connect the TP1 connector to an oscilloscope
=> check the oscillation with an oscilloscope and SR785 => OK

Connect the CTRL connector to an oscilloscope
=> check the oscillation with an oscilloscope and SR785 => OK

9) EXC check
Connect a function generator to the exc port.
Set the FG output to 1kHz 2Vpk. Check the signal TP1
Turn off the exc switch -> no output
Turn on the exc switch -> nominally 200mVpk

=> OK

10) Openloop transfer function

Connect SR785 FG->EXC TP2->CHA TP1->CHB
EXC 300mV 100Hz-100kHz 200 line

Network Analyzer (AG4395A)
EXC 0dBm TP1->CHA TP2->CHB, measure A/B
801 line
CHA: 0dBatt CHB: 0dBatt
1kHz~2MHz
UGF 133kHz, phase -133.19deg = PM 47deg

11) Calibrate the output with the trimmer on the front panel

13dB setting -> 12.89dBm (maximum setting)

12) Check MON, BIAS and CTRL outputs,
CTRL:    2.95V
MON(L):    6.5mV
BIAS(L):    1.81V
MON(R):    10.7mV
BIAS(R):    1.85V

13) Output check
4+0dB    3.99dBm
6    5.89
8    7.87
10    9.87
12    11.88
14    13.89
16    15.89
18    17.92
20    19.94
22    21.95
24    24.00
26    26.06

4dB+
0.0    3.99
0.2    4.17
0.4    4.36
0.6    4.56
0.8    4.75
1.0    4.94
1.2    5.13
1.4    5.32
1.6    5.53
1.8    5.73
2.0    5.92
2.2    6.10

16dB+
0.0    15.82
0.2    16.11
0.4    16.31
0.6    16.51
0.8    16.72
1.0    16.92
1.2    17.12
1.4    17.32
1.6    17.53
1.8    17.72
2.0    17.92
2.2    18.13

26dB+
0.0    26.06
0.2    26.27
0.4    26.46
0.6    26.58
0.8    26.68
1.0    26.69
1.2    26.70
1.4    3.98
1.6    3.99
1.8    3.99
2.0    3.99
2.2    3.99

 

 

 

  229   Sat Jul 25 17:24:11 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

(Calibration for Attachment 5 corrected Aug 27, 2015)


Now the test procedure fo the unit is written in the document https://dcc.ligo.org/LIGO-T1500404

And the test result of the first unit (S1500117) has also been uploaded to DCC https://dcc.ligo.org/LIGO-S1500117

Here are some supplimental information with plots

Attachment 1: OLTF of the AM amplitude stabilization servo.

Attachment 2: CLTF/OLTF of the 2nd AM detector self bias adj servo

The secondary RF AM detector provides us the out-of-loop measurement. The secondary loop has an internal control loop to adjust the DC bias.
This loop supresses the RF AM error signal below the control bandwidth. This has been tested by injecting the random noise to the exc and taking
the transfer function between the primary RF AM detector error (MON1) and the secondary one (MON2).

Then the closed loop TF was converted to open loop TF to see where the UGF is. The UGF is 1Hz and the phase margin is 60deg.

Above 10Hz, the residual control gain is <3%. Therefore we practically don't need any compensation of MON2 output above 10Hz.

Attachment 3: Comparison between the power setting and the output power

Attachment 4: Raw power spectra of the monitor channels

Attachment 5: Calibrated in-loop and out-of-loop AM noise spectra

Attachment 6: TFs between BNC monitor ports and DAQ differential signals

BIAS2 and CTRL look just fine. BIAS2 has a gain of two due to the differential output. The TF for CTRL has a HPF shape, but in fact the DC gain is two.
This frequency response comesfro that the actual CTRLis taken after the final stage that has LPF feature while the CTRL DAQ was taken before this final stage.

MON1 and MON2 have some riddle. I could not justify why they have the gain of 10 instead of 20. I looked into the issue (next entry)

Attachment 7: TF between the signals for the CTRL monitor (main unit) and the CTRL monitor on the remote control test rig

The CTRL monitor for the test rig is taken from the CTRL SLOW signal. There fore there is a LPF feature together with the HPF feature described above.
This TF can be used as a reference.

 

  230   Tue Jul 28 18:36:50 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

Final Test Result of S1500117: https://dcc.ligo.org/LIGO-S1500117


After some staring the schematic and checking some TFs, I found that the DAQ channels for MON2 have a mistake in the circuit.
Differential driver U14 and U15 of D0900848 are intended to have the gain of +10 and -10 for the pos and neg outputs.
However, the positive output has the gain of +1.

Daniel suggested to shift R66 and R68 by one pad, replace with them by ~5.5K and add a small wire from the now "in air" pad to
the GND near pad 4.

The actual modification can be seen on Attachment 1. The resulting gain was +10.1 as the resisters of 5.49k were used.

The resulting transfer function is found in the Attachment 2. ow the nominal magnitude is ~x20.

You may wonder why the transfer function for MON1 is noisy and lower at low freq (f<1kHz). This is because the input noise of the FFT analizer
contributed to the BNC MON1 signal. High frequency part dominated the RMS of the signal and the FFT analyzer could not have proper range
for the floor noise. The actual voltage noise comparison between the BNC and DAQ signals for MON1 and MON2 can be found in Attachment 3.
 

  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

  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

  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

  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.

 

  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)
  16   Mon Aug 13 16:59:11 2012 KojiCleanGeneralRoom Cleaning Log

Floor wiped with a wet wiper (Aug 13, 2012)
Floor wiped with a wet wiper (Aug 15, 2012)
Floor wiped with a wet wiper (Sep 25, 2012)
Air conditioning prefilter replaced (Sep 25, 2012)
Floor wiped with a wet wiper (Oct 01, 2012)
Floor wiped with a wet wiper (Nov 06, 2012) / ATF too
Floor wiped with a wet wiper (Jan 04, 2013)
Floor wiped with a wet wiper (Mar 23, 2013)
Floor wiped with a wet wiper (Apr 17, 2013)
Air conditioning prefilter replaced (Apr 17, 2013)
Floor wiped with a wet wiper (Jun 24, 2013)
Removing Vladimir's mess. Floor swept with a broom (Jun 26, 2013)
Completed removing Vladimir's mess. Floor swept with a wet wiper (Jun 27, 2013)
Air conditioning prefilter replaced (Sep 12, 2013)
Floor wiper head replaced. (Dec 10, 2013)
Floor wiped with a wet wiper (Dec 10, 2013)
Floor wiped with a wet wiper (Apr 1, 2014)

Air conditioning prefilter replaced (Dec 30, 2014)
Air conditioning prefilter replaced (some time in 2015...)

Floor wiped with a wet wiper (Dec 1, 2015)
Floor wiped with a wet wiper (Aug 23, 2016)
Air conditioning prefilter replaced (Aug 8, 2017) = 1 stock remains

  58   Tue Jan 22 17:56:32 2013 KojiMechanicsGeneralRotary stage selection

Newport UTR80

Newport 481-A (SELECTED)

  • Sensitivity: 15 arcsec
  • Graduations: 1 deg
  • Vernier: 5 arcmin
  • Fine travel range: 5 deg
  • With Micrometer

Newport RS40

  • Sensitivity: 16 arcsec
  • Graduations: 2 deg
  • Vernier: 12 arcmin
  • Fine travel range: 10 deg
  • Micrometer BM11.5

Newport RS65

  • Sensitivity: 11 arcsec
  • Graduations: 2 deg
  • Vernier: 12 arcmin
  • Fine travel range: 10 deg
  • Micrometer SM-06 to be bought separately

Elliot science MDE282-20G

  • Sensitivity: 5 arcsec
  • Graduations: 2 deg
  • Vernier: 10 arcmin
  • Fine travel range: 10 deg
  • Micrometer 2 arcmin/1div
  • Metric

Suruga precision B43-110N

Thorlabs precision B43-110N

  408   Thu May 20 17:03:50 2021 KojiGeneralGeneralSRS LCR meter SRS720 borrowed from Downs

Item loan: SRS LCR meter SRS720 borrowed from Downs. The unit is at the 40m right now for testing with an excelitas PD. Once it is done, the setup will be moved to the OMC lab for testing the high QE PDs

  370   Mon Jul 1 12:49:42 2019 KojiOpticsCharacterizationScattering measurement of A and C mirrors

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

  351   Mon Apr 22 09:54:21 2019 JoeGeneral Shortening cavity (A5,A14,PZT11,PZT22) to get closer to design FSR

[Koji,Joe,Philip,stephen]

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

CM1 inner screw pos: 11.5

cm1 outer screw pos: 33.5

cm2 inner screw pos: 11

cm2 outer screw pos: 13

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

CM1 inner screw pos: 11.5+37.5 = 49

cm1 outer screw pos: 33.5+37.5= 71

cm2 inner screw pos: 11+37.5 = 48.5

cm2 outer screw pos: 13+37.5 = 50.5

The screws on the micrometers were adjusted to these values.

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

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

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

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

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

CM1:

  • inner = 0.405mm
  • outer = 0.67mm

CM2

  • inner = 0.507mm
  • outer = 0.42mm

want to increase by 1.7/4 = 0.425, so

CM1:

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

CM2

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

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

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

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

123-7699 = CM2

123-7697 = CM1

 

 

  36   Thu Nov 8 19:47:55 2012 KojiElectronicsConfigurationSolder for PZTs

Rich saids:

I have ordered a small roll of solder for the OMC piezos. 
The alloy is: Sn96.5 Ag3.0 Cu0.5

  48   Mon Dec 31 03:10:09 2012 KojiOpticsGeneralSolidWorks model of the OMC breadboard
  52   Sun Jan 6 23:22:21 2013 KojiMechanicsGeneralSolidWorks model of the OMC suspension

D0900295_AdvLIGO_SUS_Output_Mode_Cleaner_Overall_Assembly.png

  284   Sat Jul 1 21:33:18 2017 KojiGeneralGeneralSome purchase notes

- Forgot to close the cylinder valve...

v HEPA prefilter (20"x20"x1" MERV 7)

- Replace the filter for the air conditioning

v Texwipe TX715 SWAB http://www.texwipe.com/store/p-817-tx715.aspx

v Gloves ~3 bags
VWR GLOVE ACCTCH NR-LTX SZ7.0 PK25 79999-304 x3
VWR GLOVE ACCTCH NR-LTX SZ7.5 PK25 79999-306 x1

v Vectra IPA soaked cloths

v Sticky mats


  • GLOVE ACCTCH NR-LTX SZ7 PK25 / 79999-304 / PK4
  • GLOVE ACCTCH NR-LTX SZ7.5 PK25 / 79999-306 / PK1
  • WIPER 100% IPA 23X23CM PK50. / TWTX8410 / PK2
  • SWAB CLEANTIPS ALPHA PK100. / TW-TX715 / PK1
  • MAT CLEAN ROOM 18X36IN BLUE / 89021-748 / CS1 (Qty4)
  • FILTER PLET AIR MERV8 20X20X1 / 78002-422 / EA4 / Direct from Supplier

ORDERED AUG 9, 2017

  138   Wed Jun 5 18:19:51 2013 KojiGeneralGeneralSome recent photos from the OMC final test at CIT

Applying First Contact for the optics cleaning


PD alignment / scattering photos

Cabling

Cabling (final) 

  213   Mon Jul 21 01:02:43 2014 KojiMechanicsCharacterizationSome structual mode analysis

Prisms

Fundamental: 12.3kHz Secondary: 16.9kHz

PRISM_12_3kHz.png PRISM_16_9kHz.png

DCPDs

Fundamental: 2.9kHz Secondary: 4.1kHz

DCPD_2_9kHz.png DCPD_4_1kHz.png

QPDs

Fundamental: 5.6kHz Secondary: 8.2kHz

QPD_6_0kHz.png QPD_8_2kHz.png

  120   Mon May 6 19:31:51 2013 KojiOpticsCharacterizationSpot position measurement on the diode mounts

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

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

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

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

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

  121   Wed May 8 15:08:57 2013 KojiOpticsCharacterizationSpot position measurement on the diode mounts

Remeasured the spot positions:

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

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

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

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

  158   Tue Aug 27 17:02:31 2013 KojiMechanicsCharacterizationSpot position measurement on the diode mounts

After the PZT test, the curved mirrors were aligned to the cavity again.

In order to check the height of the cavity beam, the test DCPD mount was assembled with 2mm shim (D1201467-3)
The spot position was checked with a CCD camera.

According to the analysis of the picture, the spot height is about 0.71mm lower than the center of the mount.

ELOG V3.1.3-