More epoxy!.. Nor much improvement byt the remaning peak moves. So that 300 Hz is related only to the connection of the two mounts.

After halfway success with a drop of epoxy between the two mounts  I took it apart again, cleaned the dry epoxy and put really a lot of fresh epoxy. This removed "pitch" and "yaw" resonances on X, however small peaks are still observed on Y.

The PZT mount holds in the Newport mount with only one set screw. I released the screw and put a drop of 5 min epoxy between the two mounts. After this the "pitch" resonance was almost gone and the "yaw" resonance reduced.

I glued the PZT mount to a magnetic post to see is it affects the resonance. The peek at about 300 Hz moved right and reduced the magnitude in Pitch

I change setup to increase the distance between the QPD and PZT because I wanted to repeat the measurement at 0.1 V amplitude on the PZT. The new measurement showed that the reason of the bad curve was not the QPD accuracy. So probably the PZT riches it`s accuracy below 1 V. Also the resonance at about 300 Hz moved. I have tighten the PZT mount to the orange post differently this time (stronger). This could be a reason.

Two front screws on the PZT sleeve mount out and back in to checj the repeatability. No big difference has been observed.

I started to assemble the interface board power regulators and sense board in clean room located in dows 2n floor. EFM Cube2 and Cube3 are partially assemble, sense boards and interface board are connected thru the interface wires. One cable for each sense board.

Luis,

I got 4 different quotes for the build and stuffing of pcb's from two different designs, the next tables show the differences.

I am not 100% sure if the quote that I received from Manufacturing Services include the SMD stuffing material, this price is quite different if we compare this with Screaming Circuits and Advanced Circuits.

I will ordering the boards using Sunstone and Digikey, for us to built these here...

The damping coefficient for the v4 blade is    from 8 different mass measurements. The damping coefficient of the v5 blade is  from 8 different mass measurements. 

Inspected batch 2 of thinner elliptical mirror received from Brand Laser Optics & Mfg coated on one side. Uncoated surface is matte vs glassy coated side. Shiny green reflections can be observed on the coated side. The mirrors have no chipping but a bit dusty from the package. I have marked the front and back side of the mirrors on the box.

I have written a doc summarising current status of work on HSTS redesign of middle mass, including MATLAB transfer functions for a preliminary conceptual design.

See T1400290 at https://dcc.ligo.org/LIGO-T1400290

I'm currently working with Calum on change request for funding a prototype of the middle mass. Eddie is helping us to cost this based on Harrison's conceptual design.

Harrison is working on more details of the design.

Luis:

I started to create a block pieces that identify the units to be use during the HSTS wiring diagram, I started with, what I believe are the essential pieces, in these blocks I indicate what type of inputs and outputs for easy recognition when I create the actual library in Altium.  Also a preliminary block diagram was created for the HSTS chassis and wiring connection, after I verify this I will load the file on E1900106.

[Stephen, Jordan, Camille]

We continued building the Zaber XY stage, following instructions in vendor manual link with notes at E2200112 google doc.

Some notes and lessons learned:

• The stepper motors and controller are all functional, yay!
  •  A homing test using the vendor's software was conducted, videos will be posted here.
  • First homing test used travel range 1250 mm, following instructions from vendor using stepper motor p/n; however, we found that this caused a crash at the far end of travel; actual max travel from home, considering physical constraints, is approximately 1200 mm, but we ordered a stage with 1000 mm travel. So, there's extra range, but 1100 mm is a good limit.
  • Manual stop button on controller seems to only pause sometimes; useful but better to use software stop.
  • One axis had home sensor installed in reverse orientation, so the homing failed during its homing test, causing a crash at the far end of travel.
• The cable for the Y axis was supplied incorrectly, and inconsistently with the packing slip (should have been a 16 pin to 25 pin cable, p/n MC10T3L300, but we instead received a 16 pin to 16 pin cable, p/n MC03L300.
  • Until a replacement is supplied, we can wire only 2 axes at any one time.
• The X and Y axes have been structurally joined, then mounted on 6" pylons.
  • Because of some interference between the bracing and the alignment bars, these were removed and can be reapplied when the vendor gives further instruction.
  • Calipers were used to square the axes and ensure parallelism, and the free X axis was driven through the squared axes to confirm the friction feels similar through the entire travel range.
• The correct Y axis cable has been received, installed, and routed.
  • This included an international FedEx Priority overnight shipment, a quick double check that the connectors would fit, and a 24 hour vertical hang.
  • The cable guide has been finalized; this long cable runs along the long axis as the stage is driven through its range of motion, and the cable guide articulates to retain a safe bend radius.
• All three of us have learned to use the control software, Zaber Launcher.
  • Software commands may be implemented through the GUI in some cases, for convenience, but all can be routed through an ASCII protocol Terminal.
  • Documentation relating to software (manuals, tips, discoveries, lessons learned) are compiled at E2200112.
• The breadboard and A frame are assembled and mounted.
  • We still require an interface plate to come through, hopefully in April.
  • We will next consider shielding to prevent turbulence in the Hartmann WFS path.
• Laser install and optical alignment may proceed next week (April 25th).

We have a stage which is needing a bit of fine tuning, an interface plate, and some software integration work, but overall the build has proceeded nicely.

[Stephen, Jordan, Camille]

We started building the Zaber XY stage, following instructions in vendor manual link with notes at E2200112 google doc.

Some notes and lessons learned:

• The motor - controller cables need to be straightened by 24 hours of vertical hanging "to relieve packaging stresses".
• In vendor terminology, the X axis is the longer lower rail, and the Y axis is the shorter upper rail.
• The vendor recommends testing device functionality before completeing structural assembly.
• We have all motors attached and are just about to attach the Y axis rails onto the X axis alignment bars.

With the cables needing to hang and the device functionality testing depending on those cables, we have paused until Friday. Complete stage structural assembly anticipated tomorrow!

We bought a thorlads QPD to measure the transfer function of the PZT actuator. today I wired a box to connect the QPD to a power supply and to read pich, yaw and the sum.

Luis:

A block diagram for HSTS and HRTS were created, these might need a double check to verify if everything is well configured. Diagrams describe a connection between all components or chain of components for suspension HSTS or HRTS units. HSTS has a top, middle and bottom masses, while HRTS only has top and bottom masses. These diagrams will help when altium wiring diagram are created. Documents can be seen at E1900106 and E1900128.

Luis:

A short wiring diagram for a suspension system that only inlcude MC2 Top was created to verify script program and verify the creation of csv file that list items of this system. In the list we can see the length of wires, chassis used, DCC numbers related to chassis, cables, etc.

The modified Viewport cover was installed using the new adapter ring. No leaks. Pump down looked Ok.

Luis:

This is a note on how the valon 5015 and 3010 are connected to generate the clock frequency signal for the adc or dac filters.

Firts, save frequency configuration on memory by using the valon 5015 gui, the frequency on valon 5015 is 33.554432MHz, this frequency is divide by the Valon 3010. Frequency is divided by 32 then by 16 to generated a final frequency of 65.536KHz. This signal can be seen at the valon 3010 ttl output. The clock voltage level at the valon 3010 output is around 3.5v; for this reason we added a logic level converter "PRT-14765" to increase clock voltage to 5v. This will be use if for some reason the clock generated by the valon 3010 does not work with dac or adc. The PRT-14765 was setup on a pomana box, part number 3231.

Luis:

I went back to the CyMax box we are making and created a cable that will connect the CLK signal into the ADC or DAC Filters. I Also verified the CLK signal at the IO Chassis level, want to verified voltage level, frequency and logic of the signal, 5v, 65738Hz.

During the testing of the Valon 3010 we noticed something interesting, a noisy clock output signal; turns out that the ground connection on the TTL output is not connected in this unit, need to verify all units. Contacted Valon Engineer and He said "Some Valon 3010 version 1 were built missing the ground connection".

Contributors: Craig, Alexei, Stephen

Project: VMD Testing (BK Connect)

Summary: Non-excitation measurements by laser vibrometer were successful. We will work on curve fitting the spectra to extract Qs, but this technique seems to work well.

Description

The following measurements have been made:

• Bolted-base non-excitation measurement in the transverse direction
• Glued-base non-excitation measurement in the transverse direction
• Glued-base non-excitation measurement in the longitudinal direction

Remember, our bolted-base excitation measurement in the longitudinal direction was poor, so we did not feel like the non-excitation measurement would be informative.

We made measurements of a field calibrator reference, which oscillates at 159.2 Hz at a velocity of 10 m/s. We measured the velocity of this peak using a separate setup within our VMD Testing project, using 2 vibrometers. We adjusted the sensitivity of each vibrometer in our hardware table using the proportional relationship:

[Old Sensitivity * (Measured Velocity / Nominal Velocity)] = [New Sensitivity]

We then collected non-excitation measurements in two directions at once using the two calibrated vibrometers, and then swapped the response direction of each vibrometer to make a second measurement. There was good agreement between the two vibrometers, and the technique seemed very promising for resolving the peaks fully.

We investigated comparison with the autospectrum of the excitation measurements, and we'll tie up lose ends on that - seems like a visual check of the shape and the prominence of the resonance peak will be a good way to confirm that this technique is working.

Next Steps

1. Craig - Finalize plots of non-excitation measurements and push to next rev of T1800474
2. Craig - Look into matlab curve fitting toolbox - looking to extract Q from noisy non-excitation measurements

Photos/Figures

None to share this time - oops!

The following questions I came up with after listening in to the VMD design review on 2/13/2019

1) One method of tightening the VMD assembly is the allen key pattern in the top of the copper rod. If this process of tightening the assembly needs to be repeatable, how will the distortion of this pattern be taken into account? Just in the lab, the during re-assembly there has become noticeable distortion of this key pattern making it difficult to obtain the correct torque when tightening the assembly. 

2) I believe I heard there can be a +/- 1 Hz difference in resonance frequencies between Air/Vacuum, but how will epoxy react to this difference? Also, is there concerns of outgassing of the epoxy?

I hope to have those questions clarified by Stephen/Calum next week

Luis:

A fixture to energize the 800MHz VCO was assembled, this unit was implemented with a 9v battery,a mechanical potentiometer and a low pass filter. After testing this fixture we realized that the mechanical potentiometer is inducing extra noise at low frequencies. A new version of the device was assembled, only the filter was kept, now we will proceed to test the VCO with the Valon 3010, to lower frequency to 80MHz. To power the modified box we use a Martell IVC-222HPII power source.

Net drifts for BRDs:

Yesterday I spent some time adjusting the masses of the BRD to tune the resonances to the dummy BS resonances. Here is the summary of the attempts:

Afterwards, I checked the values of the brd Q with the vibrometer:

• Bounce mode: Q = 86 +/- 3 with f = 16.80 +/- 0.1 Hz (mean of 19 over 30 meausrements)
• Roll mode: Q = 80 +/-2  with f = 24.6 +/ 0.15 Hz (mean of 16 over 30 measurements)

Then I installed the BRD on the dummy BS. The bounce mode Q is only reduced by a factor 2 (Q ~ 2600, see figure 1) but the roll mode is better damped (Q reduced to 600, see figure 2).

We need to remeasure the modes of the suspension alone and improve the tuning by further adjusting the masses.

Tuning of BRD2 modes and both are in the target range

Roll Mode (mean of 3 measurements):  f=24.240 Hz,  Q=100.34

Bounce Mode (mean of 4 measurements): f=16.708 Hz,  Q=134.88

Constructed and tuned the BRD9 and BRD10 V5. The masses on each BRD were:

In the attached excel spreadsheet are the measured frequencies of the BRDs before and after tuning the dampeners. The BRDs were tuned to be with +/- 1% of the ideal value for the dampeners. These frequencies are 16.69 Hz for the bounce mode and 24.34 Hz for the roll mode. Also, the change in frequency over this week-long process was recorded to determine potential drift of the dampeners. 

Data is in attached excel file.

Overnight the Bounce mode of BRD7_v5 drifted 0.16% which is surprising if we compare it to the drift from the previous month which was lower and in the other direction. The Roll mode of BRD7_v5 drifted by 0.06% and also in the positive direction. As mentioned in elog 154 we want to tune the BRD to 16.69 Hz for Bounce and 24.34 Hz for Roll.

We tuned the bounce side at 0.25% from the target at 16.731 Hz. We noticed that the Q factor increased from 60 to 90 during the tuning. Could it be related to the tightness of the screw? 

We tuned the Roll side 0.07% from the target at 24.347 Hz. Again we see an increase in the Q factor to over 100.

Regina's problem statement:

 I attached examples of two measurements I got and wanted to know if these look reasonable. I took 6 measurements total, and I attached the first and last measurements. The graph on the last page is a picture of the weighting step for reference.

I didn't see significant ring down in all my measurements. Is this to be expected? I thought since the baffle is now rigidly mounted, the vibration should go almost to zero. I was also getting some low amplitude noise throughout the entire frequency domain that didn't show up in the first couple measurements I took. I tried to reset the vibrometer like you mentioned but they were still present. Is this a problem?

Stephen's reply:

1) Vibrometer may need a higher diffusivity surface to improve signal level.

Replying to your absence of ring down in your measurements - I agree that it looks like the vibrometer output is not behaving well, for one reason or another. In the freely suspended case, I was thinking this was due to large yaw and pitch motion causing high signal variation. Given that the symptom occurs when the baffle is fixed, I think the likeliest reason is the low signal, due to the low scatter and highly specular surface finish of this baffle (aka shiny). One way to troubleshoot would be to attach a compliant, diffusely reflecting material to the surface - think a small square of the adhesive-coated part of a Post-It note, for example - then tune the focus of the vibrometer and see if the vibrometer's signal level bar improves. If the signal level improves, take a hammer-excited measurement, and see if you see any ring down. If this behaves as you might expect, you could generate mode shape data with your excitation roving around the surface of the baffle while your response is fixed - just one baffle point would need your diffuse Post-It square (I might go with a central, or near central, location).

2) Test Article is not well understood, so try measuring something that has been characterized before.

If you try playing with the diffusivity and focus but the signal level doesn't improve, or if you don't see any ring down still, try pointing the vibrometerat the suspension cage and exciting the suspension with the hammer - that should give some real signal regardless of the precise setup, and if that gives similarly mystifying results, let me know and we can think a little harder about what might be going on. I feel pretty confident that between these two tests, you will find an answer.

3) Add another transducer (ie. a witness accelerometer) for comparison.

Another way to support your understanding of your setup (and a good practice) would be to mount the accelerometer to the suspension cage, adjacent to the baffle mounting brackets, or even to the mounting brackets themselves. This accelerometer would supply a witness to the low frequency resonances of the cage, which you may excite during your measurements, and might also provide some insights to the baffle panel resonances (rigid coupling with lower modal mass = smaller vibrations, but likely still above the noise floor of the accel) supporting your eventual successful vibrometer measurements.

4) Notes about mounting an accelerometer.

Mounting would involve collecting a ~[1mm x 1mm x 1mm] chunk of beeswax, spreading the beeswax onto the face of the accelerometer opposite the cable (I like to press it with the outer, flat-ish surface of my thumb nail to spread), and pressing the beeswaxed face onto a flat surface - think a 5 second push with all of your arm strength, which should create a thin layer with plenty of tackiness to hold the accel in any orientation. If it doesn't seem like it could hold for a day, then you might need more beeswax, or more force to create that thin layer. Note: the main way that an accel can go from useful to not is to experience a shock event, so I would recommend that you use some kapton tape to affix the accelerometer cable to the suspension cage - this will strain relieve your cabling and provide a fall restraint, and the potential for the cabling to influence the measurement is minimal here because it is remote from the baffle.

After some digging on Jay Heefner old computer files, I finally found the panels for the Triple Coil drivers, I added some panel numbers and I save documents into DCC, the numbers are D1900419, and D1900418.

I also created an assembly drawing since D1001242 only shows a picture of chassis without any description, see below image.

I created a cable drawing for the cables need to connect the monitor board and to suspension satellite amplifier.

Nick is troubleshooting Transfer Function Board from the PDH servo box, somehow the pcb board is getting hot and apparently pulling high current over some time. Nick isolated the input op amp THS4631 to check functionality, first ar dc then will do at ac. When testing at dc he found an oscillation, he pointed out the -12v power rail. He apply a DC voltage of 1v to the input and check the op amp, that in theory will give over -3.93v dc, Nick's reads -4.12v dc.

The op amp is getting hot, it might need a pcb thermal paddle to suppres the heat. Seems to me that the op-amp is having a hard time to drive the input capacitance. Nick will remove C20 from pcb and verify if this help with op amp heating and also with the oscillation seen at the negative voltage. More to come...

Luis:

A few weeks ago, I received a new topology for Transfer Function (Johannes modification) circuit; this board still has 5 op-amp stages that will be activated in a different way. Still 3 switches but the activation is as follow: SW1 activate OP AMP1, SW2 activate OP AMP2 and OP AMP3, SW3 activate OP AMP4 and OP AMP5. I ran some simulations and the results are below. I need to claryify some points with Johannes since some simulated results are different, appears that switch activation was run in a different way for some plots, but the final configuration appears ok.

Luis:

A test was conducted to verified the behaviour observed by Nick at MIT. "High current on TF board"

From inspection and dc test conducted, the unit "yes" saturate over time, and make this saturation worse when all integrators are enable at the same time. Not high current was observed during test, only the incremental current due to the saturation proper of the op amp integrator action.

Luis:

I created and tested a toroidal coil with 6.5µH, this was completed by using a micrometal core T22-6 (AL=4.5nH/N², 36.6) and T25-6 (AL=2.7nH/N² , 47.3turns) and using a Belden 34AWG wire, this is with the purpose of testing RFPD for 6.25MHz. It is kind of tricky to get the correct inductance, I need to watch loops (not get on top of each other and not to loose). At the end I got a coil with 6.46µH , 1.859Ω, and 253.69Ω, close enought for the test(6.5µH).

Posting here for reference the best achievable Q for the damped BS as a function of the mass ratio of the damper mass and BS mass (see figure attached, along with the Matlab code). This is mainly based on a code from Norna (T1600259), with a line that computes the structural damping constant of the damper from the mass ratio (see Equation 12 in T1500271).

Currently we are using masses of 5g for bounce (3g for roll) for the damper. The modal masses of the BS are 27.78 kg (bounce mode) and 12.9 kg (roll mode). The mass ratio is therefore 1.8e-4 (2.3e-4). It means that we could achieve a Q ~ 120 in case of perfect tuning or Q ~ 200 for a mistuning by 0.5% for the bounce mode.

For the roll mode, we could do slightly better, with a Q~ 110 if the damper is perfectly tuned, and a Q ~170 for 0.5% detuning.

This is image of the 4 sectioned green lantern on the mock up quad at cit.

Actions

1) BA to complete cabling for use in chamber 

2) CT to clean & bake

3) KG to practice imaging. unit is in 318 Downs on quad mock-up.

Abstract

The purpose of this test was to evaluate a spring plate in a custom optic mount design which will be deployed in the reworked and upgraded PMC Spacer Assy per D1600270.

Summary of Results (Fit)

Mechanical inspection of the fabricated showed conformance to manufacturing specifications. Assembly of the Fit Test Interface Assy D1600398 in the nominal configuration was successful.

• The primary source of assembly clearance was the 0.030” radial gap between the mirror and the 1in. Mirror MT.
• Secondarily, assembly clearance was evident in the clearance bore bolt circle in the 1in. Mirror MT. for the M2.5 x 0.45 SHCS.

Some additional consideration (Tooling? Interfacing part?) may be necessary to combat these sources of “slop” and permit repeatable assembly.

Summary of Results (Holding Force)

The Fit Test Interface Assy D1600398 was laid flat on the work bench with the normal axis of the mirror vertical. The force required to overcome the static friction for a given spring plate defection and induce macroscopic translation was evaluated as follows:

• 0.050” deflection (nominal): 6 +/- 0.5 ounces of force (1.7 newtons)
• 0.030” deflection: 4 +/- 0.5 ounces of force (1.1 newtons)
• No spring plate: no measurement, as this force was too small for this experimental set-up

In comparison, the weight of the optic is estimated to contribute a force of 1.6E-2 newtons in the nominal orientation. The optic did not sag in the mount when held in the nominal configuration and orientation for 2 hours.

In shipping configuration, the set screws were found to couple rigidly to the barrel of the optic and provide sufficient static friction to withstand jarring motions. The design seems to be sound from a shipping point of view.

Summary of Results (Comparison with COTS)

Two Commercial Off-The-Shelf (COTS) optic mounts were investigated. Barrel contact points, namely two flats and a preloading point-contact plunger, were used in conjunction with a spring plate. The assembly was rigidly coupled with high static friction constraining all degrees of freedom.

Perhaps barrel contact points should be employed in the LIGO design.

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

Full Description of Experiment

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

COTS Spring Plate Mounts

Two models of Commercial Off-The-Shelf (COTS) Low Outgassing optic mounts from Newport which provide axial clamping using the COTS 906919-02 Mirror Mount Spring Plate were investigated. Both use the Spring Plate in conjunction with barrel contact points, namely two flats and a preloading point-contact plunger.

An optic is loaded into these mounts by using the barrel to depress the plunger, then tilting the optic into flush face contact with a retaining lip that is integral to the mount. The plunger then pushes the optic into its seat on the two flats (visible contacting the right hand site in the image below). Subsequently, the blade spring is bolted to the exposed face, and the assembly is rigidly coupled with high static friction constraining all degrees of freedom.

Optic Mount models are:

• NewFocus (Newport) 902817-04 (9817-6-NI-K) (pictured below, with dirty optic)
• NewFocus (Newport) 902816-04 (9814-6-NI-K)

Inspection

The parts procured for the Fit Test Interface Assy D1600398-v1 were received in good condition. Using micrometers, calipers, and pin gages, Stephen employed partial inspection of mating and critical features to establish that the parts were made to specification by the vendor. The parts consisted of the COTS 906919-02 Mirror Mount Spring Plate (Qty 25, New Focus / Newport), the D1600233-v1 1in. Mirror MT. (Qty 1, ProtoLabs), the D1600397-v1 Base Plate (Qty 1, ProtoLabs) and assorted COTS hardware and fasteners.

The only item worth raising from this inspection is the difficulty of inspecting the 1.010” Diameter pocket in the D1600397-v1 base plate. No accurate measurement could be made due to the nominal .030” high shoulder, the nominal .0075” machine tool radius, and the un-deburred lip, all of which limited the contact area and precision for the calipers. A fit check of the PZT showed that the pocket was large enough to insert the PZT, and this was taken to be sufficient to “Pass” the size dimension on this feature.

Assembly

To assemble the Fit Test Interface Assy, the following procedure was followed:

1. The COTS 906919-02 Mirror Mount Spring Plate was bolted to the D1600233-v1 1in. Mirror MT. and the subassembly was placed flat on the workbench with the spring plate on the table side.
2. The 25 mm Diameter x 5 mm Thick mirror was laid flat on top of the spring plate within the 1in. Mirror Mount, with the HR-coated side facing away from the table. Now, the AR-coated side was in contact with the Spring Plate.
3. The M2 x 0.4 set screws were tightened onto the barrel of the mirror until rigidly coupled, with the mirror centered by eye in the 1in. Mirror Mount. THIS WAS NOT A VERY PRECISE CENTERING OPERATION, but using a pin gage as a spacer, I was able to position the optic within 0.005” of the center of the mount.
4. The 1in. Mirror Mount was lowered toward the surface of the D1600397-v1 Base Plate, until the HR-coated side was registering on a single plane with three locations of point contact.

5.  The M2.5 x 0.45 SHCS were tightened by a couple of turns, indexing the 1in. Mirror Mount BUT NOT LOADING THE SCREWS. The 1in. Mirror Mount was NOT in contact with the Base Plate. THE SLOP IN THE CLEARANCE BORES DID NOT PERMIT PRECISE CENTERING AT THIS STAGE.
6. The set screws were loosened and retracted into the threaded bores to prevent any possible contact with the barrel of the mirror.
7. The 1in. Mirror Mount was bolted to the Base plate using the M2.5 x 0.45 SHCS with tightening conducted in stages, so that each tab was loaded approximately 1 mm at a time. A final torque of 5 in*lb was applied, per T1100066 (interpolation between #2-56 and #4-40).

Note that the mirror used in this experiment was a flat mirror removed from PMC 10. See item 36 of D1001955-v2 Assembly Drawing.

Evaluation

Using the Fit Test Interface Assy D1600398 and a 36 ounce Jonard Compression/Tension Force Guage, the holding force of the 906919-02 Mirror Mount Spring Plate was tested.

This holding force was found to hold the optic tightly without macroscopic translation in the nominal mount configuration (0.050” axial deflection on spring plate) until acted upon by approximately 6 ounces of force (converted, about 1.7 newtons). This force was applied approximately perpendicular to points on the barrel of the mirror near the face opposite the 3-point contact plane.

SEE 50thou Holding Force.MOV

In contrast to the nominal 0.050” of deflection on the spring plate, under an axial deflection of 0.030” approximately 4 ounces of force (1.1 newtons) were required to overcome the static friction and induce macroscopic translation. This set-up utilized precise shims to reduce the deflection, as shown below.

SEE 30thou Holding Force.MOV

The force required to induce macroscopic translation without the spring plate installed was too small to be measured with the same set-up.

SEE NoSpring Holding Force.MOV

The weight of the optic contributes a force of 1.6E-2 newtons in the nominal orientation, using a calculated volume of 0.78 cm^3 and an estimate density of 2.2 grams per cm^3. The optic was set in the Interface Assy for 2 hours under the nominal configuration, and no gravitational sag was observed (using a pin gage as a probe).

Evaluation of Shipping Configuration

In order to push the limits of the holding force of the mount for shipping purposes, the mount was carefully subjected to a repeated jarring motion (held with one hand and "clapped" firmly into the other) with the set screws driven tightly into the barrels. The contact provided by the set screws and the spring plate in conjunction was sufficient that the optic did not macroscopically move (using a pin gage as a probe). Meanwhile, when the optic was held only by the spring plate and the mount was subjected to the same jarring motion, the optic did macroscopically move. The set screw contact on the barrel is very much necessary for shipping of the optic in place within this mount in order to provide sufficient static friction to rigidly couple the optic to the mount.

Luis:

Continue testing CLF RFPD using MAX4107 and THS4631 devices as transimpedance amplifiers. An important observation is that the input capacitance from devices create different response over frequency. This was tested using the created toroid inductor with 6.05µH, CLF RFPD with MAX4107 has a resonance frequency of  6.24MHz, very close to the required 6.25MHz. Device THS4631 resonance frequency was noticed at 6.14MHz with 6.05µH(same coil than MAX4107).

Also a photocurrent test without preamplifier was perform using the MAX4107 device and noise was captured on a excel chart; after plotting the data two regions can be seen, appears that the Resistance (impedance of the system) behave more linearly between 0.06mA - 10mA, making noise increments more linear. At lower photocurrent between 0.01mA - 0.06mA the noise level is barely affected.

We received the 12 new springs made with a sandwich layer of Pyralux damping today (see dcc D1700188-v3). 

According to T1700176, the bounce and roll modes of the dummy BS in the modal lab are respectively 16.70 Hz and 24.34 Hz. Aiming for a Q~100 for the damped BS, the relative mass of the damper and the modes has to be > 2.0e-4. It means the masses have to be >= 5.556 g for the bounce mode and >= 2.580 g for the roll mode, taking into account the weight of the spring (0.168 g) and the screws (~0.49g each). I got: m_b = 0.91 + 4.23 + screw = 5.622 g for bounce and m_r = 2*1.06 + screw = 2.620 g for roll. 

Calum helped me taking the first measurement of the new BRD with the B&K software and the vibrometer. We found that the roll resonance is at 27.750 Hz (i.e. 14% too high), with a measured BRD Q of 59 (TBC).

Luis

I just added a document to DCC the describe the electrical characteristics from the Aplus Satellite Amplififer E1900355. Also a test procedure was preparer to check all connections on the Aplus Satellite Amplifier E1900245.

PZT body was taped to a v-block. An extra mirror used in the layout for stirring the beam. Pictures show a comparison between this tape mount and a sleeve mount in a U200 mount. Taping the PZT damped the two resonances (300 Hz and 1 kHz). The internal PZT resonance was stiffen.

https://services.ligo-la.caltech.edu/FRS/show_bug.cgi?id=15312

Luis:

Valon 5009 Unit 2.

This unit failed after power up, it is no locking and is no putting the correct output frequency, I  do not know when the unit was damaged. This device was used on the cryogenic lab in bidge building.

Some symptoms: when the unit is locked usually the lock button change color from red to green indicating that device is lock. Well this unit at power up sometimes pulls around 200mA with 6v or slightly less; after set the frequency to 80MHz the gui display a comment of 80MHz but the lock button never change color from red to green. One thing I noticed is that when pressing the rf output and the synth power buttons  and leaving both in off state, and then enable the synth power button unit change its state on gui by showing the lock button green. Another is tha the output signal sometimes does not correlate with the frequency setting or attenuation setting on gui and signal output. 

Unit was shipped to Valon Technologies at Redwood CA, on August 6th 2019. The unit is no longer under warranty but Stuart Rumley offer to check the unit to see if he can find the problem.

Luis:

I took some data from D1900217 and created a test procedure. Simulation results are almost in agreement with test data. Limited by SR785 when taking noise spectrum in low frequency specially between 1-10Hz.

Luis:

Recieved the pcb from screaming circuits and I found out that they installed the incorrect device in OP2177 places, 12 units were affected, they installed a SPI Flash Memory Adesto 1749 25DF081A. Screaming circuits is reviewing to see what have failed in the process, but appears that Digi-Key made a mistake since the bag containing the chips are label correctly but the parts inside are the memory ic.

I added the missing 20uF capacitors on all 4 channels.

Started to test and identified some issues with this board, fixing the errors and verifiying DC voltages.

Luis:

Since we will have a review for the repackaging of UK Satellite Modules for A-plus, see E1900084. We created the front (D1900090) and rear (D1900091) panels for the Suspension Satellite Amplifier prototype, this was completed on the effort of having a visual idea on how the new chassis will look; it is important to have in mind that the configuration of the openings for the connectors (dSub connectors) and leds might change since we have not get any feedback from the Review Panel (the review will happen in the comming days or weeks). 

This panel will have a Green Quad Level LED Indicator with part number WP9345B / 4LGD for the visual indication of the 4 channels, if any channel fails the led will stay on, indicanting that a failure ocurred (high current seen at current source section). The vacuum chamber connection (Female DB25 Vacuum Tank), the Monitor to ADC (Male DB25 Analog Rack) and the Male D15 Coil Driver Interface (Analog Rack) will be set at front panel and the Local diagnostics Female DB37 connector will be set on the rear panel. More comments will be added later as we do some more work for a-plus.

Luis:

I assembled two A-Plus Suspension Satellite chassis, and also I seriliazed the pcb boards D1900217 for these D1900089 units, the numbers are S1900540 and S1900541. In the near future I will add all information on the e-traveler, for now I need to do electrical test on these units.

Luis

Started to count all needed feedthroughs for A+ suspensions and I created the next excel sheet for reference. With this new list I will verify the Bill of Materials for all suspension structures needed for A+, and probably will need to modify the already created BOM lists and altium diagrams.

Attached are the measurements of the bounce roll transfer function of the dummy BS with BRD5 and BRD6 (v5 blades) fastened to the pum.

BRD5_v5 was built on July 16 (elog 165) and BRD6_v5 was built on August 21 (elog 198) after baking (elog 204). It was found that BRD5_v5 stopped drifting at the end of August (elog 204). They were attached on the suspension on August 28th after tuning (elog 202). The date of the measurements is recalled in the table attached, with the latests ones from December 4th, 2019. There are some measurements missing from early November unfortunately (issues with the spectrum analyzer saving data/USB key problems).

Nevertheless, we can clearly see that the BS resonances are still damped over the time period of 3 months, meaning that BRDs are still well in tune with the BS resonances. It means that they stopped drifting or that the drift is now negligeable.

Note: the measurements 206, 207, 208, 212 were taken with a lower amplitude of excitation (250 mV instead of 1V) to check if a high amplitude excitation was not introducing non-linear effects. It might be that the coherence is lower for these measurements and there are therefore less reliable.