The mode cleaner seems to be locking again. I've manually unlocked it a few times in the past 20min, and most of the time it catches lock again (maybe about 80% of the time). Other times, it starts to lock in a bad mode, and can't fix itself, so I unlock it, and let it restart and it usually does fine the second time around.
I'd like it to be a little more robust, but I'm having a bit of trouble zeroing in on the optimal alignment for quickest, most durable lock aquisition of the MC. Right now I'm going to leave it for a little while to make sure it doesn't fall apart.
While aligning the optics, we tried to start up the CCD. Although nothing should have changed since the last time I used it, the code claimed it could not find the camera. All the right leds are lit up. The only indication that something is awry is that the yellow led on the camera isn't blinking as it does when there is ethernet activity.
Jenne, Koji, Rana
After fixing up the Mode Cleaner a bit more (fiddling more with the MC_align sliders to get the alignment before locking, making sure that it is able to lock), we noticed that the MC Trans path could use some help. To align the MC, we put MC1 and MC3 back into the position where Rob left it on Thursday and then maximized the transmission with MC2. Then we went back and maximized with MC1/3 keeping in mind the Faraday. We got a good transmission and the X-arm had a transmission of 0.8 without us touching its alignment.
Upon looking at the AP table portion of the MC_trans path, we decided that it was all pretty bad. The light travels around the edge of the AP table, then out the corner of the table toward the PSL table. A periscope brings it down to the level of the PSL table, and then it travels through a few optics to the MC_trans QPD.
The light was clipping on the way through the periscope, and so the MC_trans QPD was totally unreliable as a method of fine-tuning the alignment of the Mode Cleaner. Ideally we'd like to be able to maximize MC_trans, and say that that's a good MC alignment, but that doesn't work when the beam is clipped.
1. The first turning mirror on the AP table after the beam comes out of the vacuum was changed from a 1" optic to a 2" optic, because the spot size is ~4-6mm. We were careful to avoid clipping the OMCT beam, by using a nifty U200 mount (C-shaped instead of ring-shaped).
2. We placed a lens with a RoC of 1m (focal length for 1064nm is ~2m), a 2" optic, between the first two mirrors, to help keep the beam small-ish when it gets to the periscope, to help avoid clipping.
3. Rana adjusted the angle of the upper periscope mirror, because even when the beam was centered on the steering mirror directly in front of the periscope and the spot was centered on the first periscope mirror, the beam wouldn't hit the bottom periscope mirror.
4. We noticed that the bottom periscope mirror was mounted much too low. It was mounted as if the optics after it were 3" high, which is true for all of the input optics on the PSL table. However, for the MC_trans stuff, all the optics are 4". We moved the periscope up one hole, which made it the correct height.
5. We removed the skinny beam tube which guided/protected the beam coming off the periscope after a steering mirror since it (a) wasn't necessary and (b) was clipping the beam. We cannot use such skinny tubes anymore Steve.
6. There was a lens just before the 2nd steering mirror on the PSL table portion, which we removed since we had placed the other lens earlier in the path. 2 lenses made the beam too skinny at the QPD.
7. After this 2nd steering mirror, there had been a pickoff, to send a bit of beam at a crazy angle over to the RFAM mon, which we removed. This results in a much brighter beam at the MC_trans QPD, and at the camera. The QPDs readouts are now a factor of ~3.5 higher than they used to be. These (especially the camera) could use some ND-filtering action.
8. The steering optic directly in front of the MC_trans QPD is a beamsplitter, and instead of dumping the light which doesn't go to the MC_trans QPD, we used this to go over to the RFAM mon (instead of the pickoff which we had removed).
9. Koji fixed up the optics directly in front of the RFAM mon, accomodating the new position of the input light (now at a much more reasonable angle, and about 15cm farther back from the PD). Note the beam dump which is preventing the cables from the FSS board from entering the beam path. This included removing an ND filter wheel, so the RFAM mon values will all be higher now. Koji also has the beam going to the PD going at a slight angle, so that the beam isn't directly reflected on itself, so that it can be dumped.
10. We aligned the beam onto the MC_trans QPD using the first steering mirror on the PSL table.
11. We also removed the giant wall of beam dumps separating the squeezing section of the table from the rest of the table.
Alberto will elog things about the RFAM mon, including different values of the PD output, etc.
Still on the to-do list:
A. Replace the second steering mirror on the AP table after the MC_trans light leaves the vacuum with a 2" optic, since the lens we placed isn't tight enough to make the spot small there yet. Us a U200A mount if possible, because they are really nice mounts.
B. Put an ND filter in front of the MC_trans camera, because the image is too bright.
C. Normalize the MC_trans QPD - the horz and vert are pretty much direct voltage readouts, with no normalization. They should be divided by the DC value. This lack of normalization results in higher sensitivity to input pointing.
D. Long term, next time someone wants to optimize the MC_trans path, move all the optics, including the MC_trans QPD and the camera closer to the periscope on the PSL table. There's no reason for the beam to be traveling nearly the full width of the PSL table when we're not manuvering around squeezing stuff.
E. Never, ever purchase these horrible U100 or U200 mounts with the full ring and the little plastic clips. They are the "AC28" version. Bad, bad, bad.
Image 1: The new setup of the AP table, Mc_trans portion.
Image 2: New setup of the MC_trans part of the PSL table.
The camera wasn't working because the router has no built-in dhcp server. We had to manually start the server after rebooting the computer.
The MC_trans QPD Pitch and Yaw readout on the Lock_MC screen are now normalized by the trans_sum. I used the method described in my entry elog 1488.
/caltech/target/c1iool0/ioo.db now includes:
field(SCAN, ".1 second")
field(SCAN, ".1 second")
The Lock_MC screen was changed to show these new P and Y channels.
Yesterday we found that the channel C1:MDP-POS_EXC looked distorted and had what appeared to be doubled frequency componenets, in the dataviewer. This was because the dcu_rate in the file /caltech/target/fb/daqdrc was set to 16K while the adl file was set to 32K. When daqdrc was corrected it was fixed. I am going to recompile and run all these models at 16K. Once the 40 m moves over to the new front end system, we may find it advantageous to take advantage of the faster speeds, but maybe it's a good idea to get everything working at 16K first.
Last night Rana noticed that the overflows on the ITM and ETM coils were a crazy huge number. Today I rebooted c1dcuepics, c1iovme, c1sosvme, c1susvme1 and c1susvme2 (in that order). Rob helped me burt restore losepics and iscepics, which needs to be done whenever you reboot the epics computer.
Unfortunately this didn't help the overflow problem at all. I don't know what to do about that.
Just start by re-setting them to zero. Then you have to figure out what's causing them to saturate by watching time series and looking at spectra.
We put a simple pendulum into the MDP model, and everything communicates. We're still having some kind of TP or daq problem, so we're still in debugging mode. We went back to 32K in the .adl's, and when driving MDP, the MDC-ETMX_POS_OUT is nasty, it follows the sine wave envelope but goes to zero 16 times per second.
The breakout boards have arrived. The plan is to fix this daq problem, then demonstrate the model MDC/MDP system. Then we'll switch to the "external" system (called SAM) and match control TF to the model. Then we'd like to hook up ETMX, and run the system isolated from the rest of the IFO. Finally we'd like to tie it into the IFO using reflective memory.
After the mini boot fest that Jenne did today, I checked whether that fixed the overflow issues we yesterday prevented the alignemnt of the arms.
I ran the alignment script for the arms getting 0.85 for TRX and 0.75 for TRY: low values.
After I ran the script ,C1SUSVME1 and C1SUSVME2 started having problems with the FE SYNC (counter at 16378). I rebooted those two and fix the sync problem but the transmitted powers didn't improve.
Are we still having problem due to MC misalignment?
I have spent the past couple of days gathering optics and mounts so that I can observe the modulation of the EOM attached to the circuit I built using the optical spectrum analyzer (OSA). A rough diagram of the planned layout is attached.
I also built a short SMA cable so that the EOM did not have to be connected directly to the circuit box. The cable is shown attached to the EOM and circuit box in the attached photo. After checking to make sure that all of the connections in the cable were sound, I remeasured the input impedance of the circuit; the impedance measurement (black) is shown in the attached plot with the impedance before the SMA cable was added with and without the box (green and blue, respectively--these two are almost identical). The new impedance has a strange shape compared to the original measurements; I'd like to understand this a little better, since adding extra inductance in LTSpice doesn't seem to have that effect. Since I had already taken apart the setup used for the previous impedance measurements, I had to rebuild and recalibrate the setup; I guess the difference could be something about the new calibration, but I don't really think that that's the case.
I have spent the past couple of days gathering optics and mounts so that I can observe the modulation of the EOM attached to the circuit I built using the optical spectrum analyzer (OSA). A rough diagram of the planned layout is attached.
After investigating this a bit further, I discovered that some of the components in the circuit were pressed firmly up against the inside of the box, and when they were moved, the impedance plot changed shape dramatically. I think that originally, the components were not pressed against the box, but the box's SMA joint was rather loose; when I connected this to the SMA cable, I tightened it, and this seems to have twisted the circuit around inside the box, pushing the components up against the side. I have fixed the twisting, and since the SMA joint is now tight, the circuit should no longer have any twisting problems.
A new plot is attached, showing the impedance of the circuit with nothing attached (blue), with the SMA cable and EOM attached (green), and with the EOM attached directly to it taken last friday with the old calibration of the setup (red). All three curves look roughly the same; the center peak is shifted slightly between the three curves, but the circuit with SMA and EOM is the version we'll be using, and it's central peak is close to the correct value.
The daq on megatron was nuts. Alex and I discovered that there was no gds installation for site_letter=C (i.e. Caltech) so the default M was being used (for MIT). Apparently we are the first Caltech installation. We added the appropriate line to the RCG Makefile and recompiled and reinstalled (at 16K). Now DV looks good on MDP and MDC, and I made a transfer function that replicates bounce-roll filter. So DTT works too.
The 40m-IFO vacuum envelope doors are sealed with dual viton O-rings and they are pumped through the annulos lines.
This allows easy access into the chambers. The compression of the o-rings are controlled by the o-ring grooves.
The OOC (output optic chamber)'s west side door has no such groove and it is sealed by just one single O-ring.
We have to protect this O-ring from total compression by 3 shims as shown below.
There were control shims in place before and they disappeared.
Let's remember that these shims are essential to keep our vacuum system in good condition.
I've now also trended the MOPA output power for the last 200 days to check a possible correlation with the FSS reflected power. See attachment.
The trend shows that the laser power has decayed but it seems that the FSS reflected power has done it even faster: 30% drop in the FSS vs 7% for the MOPA in the last 60 days (attachment n.2).
Here we trended also the PMC and the MZ. The drop in the PMC happens at the same rate as the MOPA's.
That let us think that the FSS transmitteed power has gone down because of the reference cavity progressive misalignment to the laser beam.
We need to adjust that alignment sometime.
The drop in the NPRO output power (upper row, 3rd plot: Ch10 C1:PSL_126MOPA_126MON) accompained an increase of "fuzziness" in PMCTRANSPD and both coincided in time with the day we tempoarirly removed the flap from the laser chiller's chiller (July 14 2009).
Stephanie has needed the doors to the PSL open all day, and still has them open, so I just turned the HEPAs on high.
For the past week Dmass and I have been ordering parts and getting ready to construct our own modified version of EUCLID (figure). Changes to the EUCLID design could include the removal of the first lens, the replacement of the cat's eye retroreflector with a lens focusing the beam waist on a mirror in that arm of the Michelson, and the removal of the linear polarizers. A beam dump was added above the first polarizing beam splitter and the beam at Photodetector 2 was attenuated with an additional polarizing beam splitter and beam dump. Another proposed alteration is to change the non-polarizing beam splitter from 50/50 to 33/66. By changing the reflectivity to 66\%, less power coming into the non-polarizing beam splitter would be ``lost" at the reference detector (1/3 instead of 1/2), and on the return trip less power would be lost at the polarizing beam splitter (1/6 instead of 1/4). Also, here's a noise plot comparing a few displacement sensors that are used to the shot noise levels for the three designs I've been looking at.
I thought slightly harder and I think that the beamsplitter stays. We will lose too much power on the first PD if we do that:
33/66: Pwr @ PD2 = 2/3*1/3*1/2 = 1/9 Pin
Pwr @ PD3 = 2/3*2/3*1/2 = 2/9 Pin
50:50 Pwr @ PD2 = PWR @ PD3 = 1/8 Pin
balancing them is probably better.
We aligned both the reference cavity and the PMC, each by looking at their Trans PD on Davaviewer, and adjusting the two steering mirrors to maximize the transmission power. We got a pretty good amount of improvement for the ref cav, but since the PMC hasn't decayed a whole lot, we got a much smaller amount of improvement.
I turned the HEPAs back down to ~50.
Stephanie and Koji
We left two carts near the PSL table.
We are using them for characterization of the tripple resonant EOM.
After Alberto and I worked on aligning the reference cavity, Rob asked the important and useful question: what is the visibility of the reference cavity. This helps tell us if we're optimally aligned or not even close.
I did a scan of the ref cav temperature, using /scripts/PSL/FSS/SLOWscan, but there seems to be no real signal is C1:PSL-FSS_RFPDDC. As shown in Alberto's 200-day plot, it does change sometimes, but if you zoom in on the flat parts, it seems like it's not really reading anything meaningful. I did a cursory check-out of it, but I'm not 100% sure where to go from here: There are (as with all of these gold-box PDs) 3 outputs: a ribbon cable (for ADC purposes I think), an SMA for the RF signal, and a BNC for the DC signal. The photodiode is clearly working, since if you stick the Lollypop in front of the PD, the cavity unlocks. I plugged a 'scope into the DC BNC, and it also behaves as expected: block the beam and the signal goes down; unblock the beam and the signal goes up. Something of note is that this readout gives a positive voltage, which decreases when the beam is blocked. However, looking at the dataviewer channel, nothing at all seems to happen when the beam is blocked/unblocked. So the problem lies somewhere in the get-signal-to-DAQ path. I unplugged and replugged in the ribbon cable, and the value at which the channel has been stuck changed. Many days ago, the value was -0.5, for the last few days it's been -1.5, and after my unplug/replug, it's now back to ~ -0.5 . The other day Alberto mentioned, and made the point again today that it's a little weird that the PD reads out a negative voltage. Hmm.
we have a tester cable, but you don't want it. Instead the problem is probably at the cross-connect. The D-cable goes to a cross-connect and you can probe there with a voltmeter. If the signal is good there, trace it to the ADC. Also trend for several years to see when this happened - Yoichi may know the history better.
Also, we still need to complete the FSS RFPD task list from last year.
For some reason a few minutes ago the FB DAQ crashed and I had to restarted.
Today I was able to make low frequency transfer function with DTT on megatron. There seems to have been a timing problem, perhaps Alex fixed it or it is intermittent.
I have attached the open loop transfer function for the un-optimized system, which is at least stable to step impulses with the current filters and gains. The next step is to optimize, transfer this knowledge to the ADC/DAC version, and hook it up to isolated ETMX.
After many issues, I finally have some Guralp box noise. I did not measure every single channel with high resolution at the low frequencies because that would have taken about 3 years, but I could perhaps take some faster measurements for all of them if necessary.
I called in the reinforcements today. Ben came over and we looked all around at all of the cross-connects and cables relating to the FSS. Everything looks pretty much okey-dokey, except that we still weren't getting signal in the DataViewer channels. Finally we looked at the psl.db file, which indicates that the C1:PSL-FSS_RFPDDC channel looks at channel 21 of the ADC cross connect thing. We followed the cable which was plugged into this, and it led to a cable which was disconnected, but laying right next to the Ref Cav refl PD. We plugged this into the DC out SMA connection of the photodiode (which had not been connected to anything), and suddenly everything was mostly golden again in dataviewer land. RFPDDC_F now has a signal, but RFPDDC is still flat.
Even though this seems to be working now, it's still not perfect. Rob suggested that instead of having this SMA cable going from the photodiode's DC out, we should take the signal from the ribbon cable. So I'm going to figure out which pin of the D-connector is the DC out, and take that from the cross connect to the ADC cross connect. This will help avoid some persnickity ground loops.
Shown below are the plots of the amplitude and phase of the Mephisto laser light modulated with a chopper as a square wave at about 1 kHz. The color bar for the phase should run from -pi to pi, and it does when I don't accidently comment out the color bar function. Anyway, the phase is consistently pi/4 or pi/4 plus or minus pi. Usually all three of these phases occur within the same image, as shown below. Also, the amplitude is a factor of two or so higher than it should be where this phase jump occurs. I think these problems are associated with the nature of the square wave. However, there is a software bug that appears to be independent of the input data: there is a rounding error that causes the amplitude to jump to infinity at certain points. This happened for only a dozen or so pixels so I deleted them from the amplitude plot shown below. I am currently working on a more robust code that will use the Newton-Raphson method for nonlinear systems of equations.
The images that I just posted were taken with the CMOS camera. We switched from the CCD to the CMOS because the CCD was exhibiting much higher blooming effects. Unlike the CCD, there is a slight background structure if you look carefully in the amplitude image, but I can correct for this consistent background by taking a uniformly exposed image by placing a convex lens in front of the CMOS. I will then divide each frame taken of the laser wavefront by the background image.
Both Guralps and the Ranger have been placed in our nice new insulated foam box, complete with packing peanuts, in the corner between the x and y arms. The Guralp breakout box has been reinstalled and everything is plugged in in prepartion for the huddle test. However, we're having some issues with ADC channels, which will be worked out tomorrow (hopefully) so that data can be collected over the weekend.
Currently, one Guralp is plugged into the three SEIS-MC1 channels. We made new channels for the second Guralp (GUR-EW, GUR-NS, and GUR-VERT), but had issues with those. So, EW and NS have been plugged into PEM_AUDIO-MIC1 and MIC2 for the time being.
I found that several of the cables are unlabeled so I'm not sure what's plugged in. In the end, I found that the TEMP_2, _3, & _44 channels were working and so I plugged in anything that looked seismic into there.
TEMP_2 is now apparently the X channel of the 2nd Guralp. If someone can figure out which cable belongs to the Y channel, please plug it into TEMP_3 and then we can fix the channel names.
I also removed (gently) all of the accelerometers from MC2's chamber. This didn't break the lock, but I intentionally broke it to make sure it reacquired fine. It did and the MC TRANS QPD showed no significant shift afterwards.
Friday, we were seeing a 2 Hz harmonic series in all of the PEM channels. Today I found that some bad person had put in a 4V (!) signal into one of the channels with a signal generator. The generator was also sneakily stuck way back inside the DCU rack. NO SECRET SIGNAL INJECTIONS!
Since the ADC has a 2Vpk range, this was saturating and putting in harmonics in all the adjacent channels. I disconnected it and turned off the function generator.
This is very nice. We have, for the first time, a real time plant with which we can test our changes of the control system. From my understanding, we have a control system with the usual POS/PIT/YAW matrices and filter banks. The outputs go to a separate real-time system which is running something similar and where we have loaded the pendulum TF as a filter. Cross-couplings, AA & AI filters, and saturations to come later.
The attached plot is just the same as what Peter posted earlier, but with more resolution. I drove at the input to the SUSPOS filter bank and measured the open loop with the loop closed. The loop wants an overall gain of -0.003 or so to be stable.
The offending beam dump has been removed, and the PMC relocked.
The second set of Guralp channels is now plugged into the PEM ADCU, into channels which are confirmed to be working. (Method: 1Vpp sine wave into channel, check with DataViewer).
Direction, Channel Name, .ini chnum, BNC plug # on ADCU
Vertical: C1:PEM-SEIS_GUR_VERT, 15023, #24
N/S (should be Y when the seismometer is put in place): C1:PEM-TEMP_2, 15001, #2
E/W (should be X when the seismometer is put in place): C1:PEM-TEMP_3, 15002, #3
There is IFO work going on, so I don't want to rename the channels / restart fb40m until a little later, so I'll just use the old TEMP channel names for now.
There is something totally wrong with the E/W channel. I can look at all 3 channels on a 'scope (while it's on battery, so the op-amps in the breakout box aren't grounded), and VERT and NS look fine, and when I jump around ("seismic testing"), they show spikes. But the EW channel's signal on the 'scope is way smaller, and it doesn't show anything when I jump.
I might use the handheld Guralp tester breakout box to check the seismometer. Also, a suspicion I have is that whoever put the box back in on Friday night after our final noise measurements left the inputs shorted for this one channel. It's the 3rd channel in the set, so it would be most likely to be stuck shorted... Investigations will ensue.
Maybe it was Russell Crowe
I aligned the MZ. The reflection went from .86 to .374
I've added the PIT and YAW dofs to the MDC and MDP systems. The pendula frequencies in MDP are 0.8, 0.5, 0.6 Hz for POS, PIT, and YAW respectively. The three dofs are linear and uncoupled, and stable, but there is no modeled noise in the system (yet) and some gains may need bumping up in the presence of noise. The MDC filters are identical for each dof (3:0.0 and Cheby). The PIT and YAW transfer functions look pretty much like the one Rana recently took of POS, but of course with the different pendulum frequencies. I've attached one for YAW.
We discussed a preliminary game plan for this project. The thing I really want to see is an ETMX RCG controller hooked into the existing frontend via reflective memory, and the 40 m behaving normally with this hybrid system, and my list is geared toward this. I suspect the list may cause controversy.
+ copy the MDC filters into SAM, and make sure everything looks good there with DTT and SR785.
+ get interface / wiring boards from Wilson House, to go between megatron and the analog ETMX system
+ test tying the ETMX pendulum and bare-bones SAM together (use existing watchdogs, and "bare-bones" needs defining)
+ work some reflective memory magic and create the hybrid frontend
In parallel with the above, the following should also happen:
+ MEDM screen design
+ add non-linear bits to the ETMX MDP/MDC model system
+ make game plan for the rest of the RCG frontend
All the channels are now good, and all the names are back to making sense.
The problem with EW2 was in fact that the alligator clip used to short the inputs during the noise test Friday night was left in the box. Not great, but now it's taken care of, and we have recorded data of the noise of the breakout box, so we can include that in our plots to see if we're at the limit of how good we can do at subtracting noise.
The channels are now named thusly:
C1:PEM-SEIS_GUR_VERT (BNC input #24, .ini channel #15023)
C1:PEM-SEIS_GUR_EW (BNC input #3, .ini channel #15002)
C1:PEM-SEIS_GUR_NS (BNC input #2, .ini channel #15001)
C1:PEM-SEIS_MC1_X (BNC input #11, .ini channel #15010)
C1:PEM-SEIS_MC1_Y (BNC input #12, .ini channel #15011)
C1:PEM-SEIS_MC1_Z (BNC input #10, .ini channel #15009)
C1:PEM-SEIS_MC2_Y (Ranger, which for the Huddle Test is oriented VERTICALLY) (BNC input #4, .ini channel #15003)
Now we wait.....and tomorrow extract the noise of each of the seismometers from this!
This afternoon we tried to improve the mode matching of the beam to the PMC. To do that we tuned the positions of the two lenses on the PSL table that come before the PMC.
We moved the first lens back an forth the without noticing any improvement on the PMC transmitted and reflected power. Then we moved the first backwards by about one cm (the order is set according to how the beam propagates). That made the things worse so we moved also the second lens in the same direction so that the distance in between the two didn't change significantly. After that, and some more adjustments on the steering mirrors all we could gain was about 0.2V on the PMC transmission.
We suspect that after the problems with the laser chiller of two months ago, the beam size changed and so the mode matching optics is not adequate anymore.
We have to replace the mode matching lenses with other ones.
the servo needs some work.
2 day trend
While writing my progress report, I redrew the Guralp breakout box circuit diagram with all the changes marked. Since only one hard copy exists, I thought it might be useful to post my drawing up in case it is needed for any reason. The two drawings are the same - the second has just been broken into two parts to make it easier to fit on a normal 8.5 x 11 or A4 sheet of paper. The gains for each opamp have not been marked, but they could very easily be added in if necessary. The black resistances and capacitances are the originals. All changes have been indicated in blue.
I was able to observe the three sets of modulation sidebands created by the EOM + triply resonant circuit yesterday. Quantitative results will be posted later.
Spent a lot of time aligning tonight. The BS is not staying put--sometimes after a lock loss it gets badly mis-aligned.
DD handoff is working, after putting beam on REFL diodes and running senseDRM script.
I measured the magnitude of modulation as a function of frequency using the optical spectrum analyzer and an oscilloscope while generating signals using a Marconi signal generator; the results are shown in the attached plot and are compared to the expected modulation given the measured transfer function of the circuit and the nominal modulation index of the EOM used (13 mrad/V). Using the oscilloscope, I found the resonant peaks to be at 11.11 MHz, 29.57 MHz, and 54.70 MHz. There are several different colors on the plot; this is because I had to take the data in several different segments and had to switch to measuring a different sideband partway through the measurment. I also separately found the modulation at each resonant peak for each sideband. The magnitude of modulation was measured by finding the ratio between the magnitude of the carrier and sideband powers using an oscilloscope, and calculating the magnitude of modulation from this. This method was also used to quantify the dependence of modulation magnitude on input power at each resonant peak; these results are also attached. These same results can also be plotted as modulation magnitude as a function of voltage into the resonant circuit; this is also attached (I'm not sure which is more useful).
In order to produce these results (get the measurements in mrad/V) it was necessary to measure the gain of the amplifier. I used the signal generator to input signals of varying power and measured the output signal voltage using the oscilloscope; I then repeated this process at each resonant frequency. From this I was able to calculate the gain of the amplifier to be 28.1 dB at 11.11 MHz, 27.4 dB at 29.57 MHz, and 25.7 dB at 54.70 MHz. These values are in the same ballpark as the values in the Mini Circuits data sheet (all values are ~25-28 MHz).
Today I set up the EUCLID long range michelson design on the SP table; It's the same as the setup posted earlier, but without the pickoff (at PD1), which can be added later, and a few other minor changes (moved lenses, mirrors, PDs - nothing major). I hooked up the two PD's to the oscilliscope and got a readout that pointed to more power hitting PD2 than PD3.