Today Steve was working around the 1X5 rack to strain relief the cable jungles and the jungle is now getting less jungle.
During the work he disconnected and reconnected some cables.
So for a doublecheck I checked all the suspensions to see if the suspensions are still healthy or not.
Aha, then I found a mistake.
See the pictures below. It's a very subtle difference. This wrong connection prevented MC1 and MC3 from damping.
I measured the amplitude and phase imbalances of the demod boards which have been modified. This is just a basic health check. We hope to use the script that Kiwamu is developing for a more accurate test. The script can also use these measurements as a sanity check. POP110 requires some further attention.
The RF distribution box outputs corresponding to the demod board (eg. AS55_LO --> AS55_demod) were used as LO sources. The RF signal was generated with a Marconi and held a kHz away from the LO frequency. The amplitude and phase unbalance were measured with SR785. The RF Power meter was used to check the LO power in each case.
The ~350 Hz noted in the elog below was traced to an RF modulation of the 11 MHz sideband. This modulation was set up in the Marconi which is currently supplying the 11 MHz local oscillator signal to the RF source. lt was used during the MC length study completed last week by Valera and Ryan. The frequency measured was 322 Hz.
As we do not require this any longer, I have switched off this modulation.
The Demod board with S. No. 022 (being used earlier as REFL11) has been modified. It now has SCLF-65 as its input LP filter on the PD input line and a PQW-2-90 power splitter. The unit functioning okay (I and Q signals are 90 deg apart.
The loss of Q output was traced to a possible loose solder joint and we now have both the I and Q signals after resoldering all components in the vicinity of U7 (Ref Schematic of D990511)
There is a strong oscillation around 350Hz present on I and Q signals of both REFL55_Demod and POY55_Demod. Don't know the source.
We have run out of power splitters to continue with the Demod board modification. We do not currently have an AS11_Demod board. All the others are in place and ready for the I<->Q phase angle measurement.
In summary we now have the following Demod boards in place:
[ REFL11, POY11, REFL55, AS55, POY55, POY22, POY110]_Demod
DC power supplies for the RF generation box are now in place. They are the top two of the 6 Sorensens in the OMC short rack next to 1X2.
We made the connections as we did for the RF distribution box, the power supplies labele, and the cables strain-relieved.
The power supply is not yet connected to the actual RF generation box. This should be done by Suresh or someone with the supervision of him.
We have two +18V supply on the short OMC rack, in total. One is for the RF source, the other is for the OMC PZTs, whitening, etc.
This is to avoid unnecessary ground loop although the grounding situation of the OMC side is not known to me.
All the cables needed for the AS11 PD are in place... the heliax cable runs from the AS table to the PSL rack. The LO and RF cables to demod board as well as the I and Q cables into the LSC Whitening board are connected.
The cables get rather densely packed when the LSC Whitening filter sits between the PD Interface Board and the LSC AA filter board. This makes it difficult to access the SMA connectors on the LSC whitening filter. So we shifted the LSC Whitening and AA Filter boards one slot to the right. The LSC rack looks like this just now. We have also shifted the binary cables at the back of the Eurocart by one slot so the same cables are associated with the cards.
I have checked the voltages on the connector. They are okay and I have plugged in the Sorensen power into the RF Source. The ground reference for the Sorensens comes from the 1X2 Rack ground reference lines on the south side of the rack.
I looked for the OMC ground reference. Could not find one on either of the the OMC half racks.
We have two +18V supply on the short OMC rack, in total. One is for the RF source, the other is for the OMC PZTs, whitening, etc.
This is to avoid unnecessary ground loop although the grounding situation of the OMC side is not known to me.
[Haixing / Kiwamu]
As a part of the Wednesday's cabling work, we spent some times for identifying the RFPD interface cables.
The RFPD interface cables are made of a 15 pin flat cable, containing DC power conductors for the RFPDs and the DC signal path.
The list below is the status of the interface cables.
- - - - RFPD name, (cable status) - - - -
- REFL11 (identified and labeling done)
- REFL33 (identified and labeling done)
- REFL55 (identified and labeling done)
- REFL165 (no cable found)
- AS55 (identified and labeling done)
- AS165 (identified and labeling done)
- POP22/110 (identified and labeling done)
- POX11 (identified and labeling done)
- POY11 (identified and labeling done)
- POY55 (identified and labeling done)
We still have two cables which are not yet identified. Their heads are around the LSC rack and labeled 'unidentified'
Aka, from a hotel in Pisa.
Restarted Thu May 19 00:21:49 2011 to recover from Jenne's Italian terrorism.
I've moved all of my SOS peak fitting stuff into the scripts area so that Leo can make it better:
findPeaks.m gets the data and makes the fitted spectra that I put in the previous entry.
findMatrix.m is the barely started script that ought to take the TF data and output the matrix to the MEDM screen.
I took REFL11 out from the AS table for a health check because it wasn't working properly.
The symptoms were :
- a big offset of ~ -3 V on the RF output. No RF signals.
- The DC output seemed to be okay. It's been sensitive to light.
I did a quick check and confirmed that +/- 5V were correctly supplied to the op-amps.
It looks that the last stage (MAX4107) is saturated for some reasons. Need more inspections.
At the moment the REFL11 RFPD is on the bench of the Jenne laser.
Steve pulled the top AA filter box from 1X5 which handled some of the suspensions channels. We turned off all the watchdogs before pulling it out, as well as recorded which cables were connected to which inputs.
The case is undergoing a structural modification to have the ADC adapter card which previously was loosely connected via cables, securely attached to the case.
Steve still wants to do some cabling in the rack while the box is out, and will return it this afternoon once he has finished that.
According to Suresh's LSC rack design I rearranged the input channels of the c1lsc model such that the analog signals and the ADC channels are nicely matched.
Also I updated the c1lsc model in the svn with a help from Joe. The picture below is a screen shot of the input channels in the model file after I edited it.
Job is done. Sus damping are back on. Cabling-strain reliefing are not finished yet at 1X5 and 1X4
In trying to keep the wiring of the LSC rack as neat as possible, we came up with the following channel assignments of the RF PD signals.
PDI = PD Interface, The PD Interface D-type connectors (#1 to #12) are numbered: Top -> Bottom and Left -> Right in ascending order.
The Analog channels on the LSC Whitening Filter boards are numbered similarly, 1 to 32 in four sets.
The UL signal of the shadow sensor on ETMY went to zero this evening.
This was due to a loose connection on the cross connection board on the 1Y4 rack.
In order to make them tighten, a combination of stand-offs and screws were installed on the connectors. They won't be loose any more.
Since REFL11 has gone I tried locking the PRMI with combination of REFL55 and AS55.
Without any pain the lock of PRMI was achieved successfully. AS55 was used to sense MICH and REFL55 was used for PRC.
Additionally I was modifying several scripts which are invoked from C1IFO_CONFIGURE.adl. Some details about the scripts will be uploaded on the wiki later.
An important thing is that now we are able to use the "restore" commands for the Y arm, X arm, Michelson and PRM locking.
The scripts will automatically acquire the lock of each DOF. The image below is just a screen shot of the medm screen where you can call the scripts.
( Still to do)
* PRM actuator response measurement
* PRC noise budget
* MICH-PRC actuator decoupling
[Steve / Kiwamu]
When Steve was working on the strain reliefs on 1X5 he found that some LEDs on the back side of the binary IO boxes were off.
There are 4 binary IO boxes and their power are directly supplied from Sorensens. According to the display of the Sorensens, the power are correctly generated.
Steve and I checked a picture of the boxes taken before he started working and we found it's been like this.
It might be just a problem of the LEDs or the fuses are blown, but anyway it needs an inspection.
Here is a picture of the back side of the boxes. You can see some LEDs are on and some are off.
The POP110 board which had the large Amplitude and Phase unbalances was examined today. It turned out that there was some stray solder which had connected the Sum port of the PSCQ-2-120 splitter to its body (ground). After I removed that the amplitude unbalance was 0.3dB however the phase was 105deg. The phase reduced to 90 deg only if the power on the splitter is around 19 dBm. So removed the AT1 (10dB attenuator) and the phase unbalance dropped to 91 deg. However this is not a sustainable solution as the ERA-5 max output is about 19.5 dBm.
As this is a side band power monitor (and not a length sensing RFPD), we can make do with a poorer phase. I will therefore replace the AT1 and adjust the residual phase with cable delay lines.
- Found the inductor which shunts the positive input of MAX4107 was not touching the ground.
This left the positive input level undetermined at DC. This was why MAX had been saturated.
The PCB has a cut, so it was surprising once the circuit worked.
- Resoldered the inductor to the ground. This made the circuit responding to the intensity-modulated beam.
- But the resonances and the notches were totally off, and the 200MHz oscillation has resurrected.
- Attached 40Ohm+22pF network between the neg-input of MAX and the gnd. This solved the oscillation.
- Made the tuning and the characterizations. The PD is on Kiwamu's desk and ready to go.
More to come later
I will try with POY55 that Koji prepared today.
- Resonant at 55MHz. The transimpedance is 258Ohm. That is about half of REFL55 (don't know why).
- 11MHz&110MHz notch
- The 200MHz oscillation of MAX4106 was damped by the same recipe as REFL11.
Eventually the DRMI was locked.
I was struggling to find a good signal port for SRC over the weekend and finally found AS55_I worked somehow. I used :
REFL11_I --> PRC
AS55_Q --> MICH
AS55_I --> SRC
A configuration script was prepared such that someone can try this configuration by clicking a button on the C1IFO_CONFIGURE.adl screen.
I don't think this signal extraction scheme is the best, but now we can find better signal ports by shaking each DOF and looking at each signal port.
More details will be reported in the morning.
(PRMI locking with slightly misaligned SRM)
First I tried locking PRC and MICH with a little bit misaligned SRM. This condition allowed me to search for a good signal port for SRC.
In this locking, REFL11_I was used to lock PRC and AS55_Q was used for MICH. This is the same scheme as the current PRMI locking.
Since the alignment of SRM was close to the good alignment, I expected to see fringes from SRC in some signal ports (i.e. REFL55, POY55 and so on).
Sometimes a fringe of SRC disturbed AS55_Q and broke the MICH locking, so I had to carefully misalign SRM so that the SRC fringes are small enough to maintain the lock of MICH.
(Looking for a good signal port for SRC)
After I locked the PRMI with slightly misaligned SRM, I started looking for a good signal port for SRC.
At the beginning I tried finding a good SRC port by shaking SRM at 100 Hz and looked at the power spectra of all the available LSC signals.
I was expecting to see a 100 Hz peak in the spectra, but this technique didn't work well because SRC wasn't within the linear range and hence didn't produce linear signals.
So I didn't see any strong signals at 100 Hz and finally gave up this technique.
Then I started looking for a PDH-like signal in time series and immediately found AS55_I showed large PDH-like signals.
So I started using the AS55_I for the SRC locking and eventually succeeded.
(Two tips for the DRMI locking)
During the locking of DRMI, I found two tips that made the locking quite smooth.
- Triggered locking
Since every LSC signal ports showed large signals from PRC somehow, feeding back the signals made the suspensions crazy.
So I used triggered locking for the PRC and MICH locking to avoid unwanted kicks on BS and PRM.
If the DC of REFL goes above a certain level, the control of PRC starts. Also if the DC of AS goes below a certain level the control of MICH starts.
These triggers make the lock smoother.
- Do not use resonant gain filters
This is really a stupid tip. When I was trying to lock MICH, the lock became quite difficult for some reasons.
It looked there was an oscillation at 3 Hz every time the MICH control started. It turned out that a 3 Hz resonant gain filter had been making it difficult.
All the resonant gain filters should be off when a lock acquisition is taken place.
During the DRMI trial I noticed that the f2p filters on PRM is not quite effective (i.e. pushing PRM in POS direction makes misalignments).
I checked the f2p filters in an easy way. I pushed POS at 0.01 Hz with an amplitude of 1000 counts and looked at the oplev error signals with / without the f2p filters.
The picture below is a time series of the POS excitation, the oplev's PITCH and YAW error signals.
You can see there still is a big coupling from POS to YAW after the f2p filters were enabled. (Its supposed to be like this)
I will redo the f2p measurement on PRM.
LSC rack 1Y2 cables are strain relieved and labeled. Spare and/or obsolete cables are laid out on the top of the beam tube and on the outside of the rack.
The POY 110 MHZ demodboard has a very touchy position in the VME crate. Watch out for it! It has to be fixed.
I closed all 8 dither loops for the Y arm initial alignment: 2x2 centering servo (this worked before) and 2x2 input beam servo for both pitch and yaw.
So far it looks pretty good - the error points go to zero and the arm power goes up to 1.
The offloading to the alignment biases and the PZTs is not yet automated.
Today the PMC, MC, and Y arm were very cooperative and a pleasure to work with.
1) Checked in the changes I had made to the c1mcp.mdl model just before leaving for Elba.
2) The c1x01 and c1scx kernel modules had stopped running due to an ADC timeout.
According to dmesg on c1iscex, they died at 3426838 seconds after starting (which corresponds to ~39 days). "uptime" indicates c1iscex was up for 46 days, 23 hours. So my guess is about 8 days ago (last Monday or Tuesday), they both died when the ADCs failed to respond quick enough for an unknown reason.
I used the kill scripts (in /opt/rtcds/caltech/c1/scripts/) to kill c1spx, c1scx, and c1x01. I then used the start scripts to start c1x01, then c1scx, and then finally c1spx. They all came up fine.
Status screen is now all green. I renabled damping on ETMX and it seems to be happy. A small kick of the optic shows the approriately damped response.
There seems to be something strange going on with the 40m frame builder.
Specifically, there is a gap in the frames in /frames/full near the start of
each 100k second subdirectory. For example, frames for the following times are missing:
To summarize, after writing the first two frames in a data directory, the next ~10 minutes of frames are usually missing. To make matters worse (for
the nds2 frame finder, at least) the first frame after the gap (and all successive frames) start at an arbitrary time, usually not aligned to a 16-second boundary. Is there something about the change of directories that is causing the frame builder to crash? Or is the platform/cache disk too slow to complete the directory switch-over without loss of data?
We found that both of the c1iscey models (c1x05 and c1scy) were unresponsive, and weren't coming back up even after reboot. We then found that the c1iscey IOchassis was actually powered off. Steve's accepts some sort of responsibility, since he was monkeying around down there for some reason. After powerup and reboot, everything is running again.
ETMY's watch dogs were found tripped. They were restored.
There appears to be a bad cable connection somewhere on the LR sensor path for the MC1 optic.
The channel C1:SUS-MC1_LRPDMon is reading back 0.664 volts, but the digital sensor channel, C1:SUS-MC1_LRSEN_INMON, is reading about -16. This should be closer to +1000 or so.
We've temporarily turned off the LRSEN filter module output while this is being looked into.
I briefly went out and checked the cables around the whitening and AA boards for the suspension sensors, but even after wiggling and making sure everything was plugged in solidly. There was one semi-loose connection, but it wasn't on the MC1 board, but I pushed it all the way in anyways. The monitor point on the AA board looks correct for the LR channels, although ITMX LR struck me as being very low at about -0.05 Volts.
According to data viewer, the MC1 LR sensor channel went bad roughly two weeks ago, around 00:40 on 5/18 UTC, or 17:40 on 5/17 PDT.
It appears the AA board (or possibly the SCSI cable connected to it) is the problem in the chain.
We replaced GE81 by PZT2907A (PNP transistor) in TTFSS #7, it's working fine.
Last time I broke Q4 transistor, which is used in the low noise power module for TTFSS, (see the schematic) and could not find another PZT2907A, so GE81 was used temporarily. Now we changed it back to PZT2907A as designed. I tested it by checking the voltage outputs of the board. It works fine, all voltage outputs are correct. I labeled one of the slot on the blue cabinet tower and kept the rest of the transistors there.
I brought TTFSS set #7 to 40m and kept it in the electronic cabinet.
note that Q4 transistor has not been replaced back to PZT2907A yet. It's still GE82.
Q3 is now pzt3904, not PZT2222A.
Here is the conclusive result for the circuit configuration for aLIGO BBPD and 40m Green PD.
- Use Mini-circuits MAR-6SM for the RF preamplifier. The 50Ohm input impedance is used for the RF transimpedance.
The maximum output is ~4dBm.
- Use Mini-circuits GALI-6 for the RF middle power amp. The gain is 12dB and the amplifier is linear up to +17dBm. i.e. This is still linear at the maximum output level of MAR-6SM.
- The total RF transimpedance is ~2k. The DC transimpedance is also 2k.
- The bandwidth is 80MHz with FFD100 and internal 25V bias. When S3399 is used, the bandwdith goes up to 180MHz
although the responsivity of FFD100 at 1064nm is better than S3399 by a factor of 1.5. At the 40m we will use S3399 for the green BB PD.
- By adding an LC network next to the PD, one of the unnecessary signal can be notched out.
As an example, 9MHz notch was placed for the FFD100 case.
- Noise level: ~10pA/rtHz as a floor noise level at around 30MHz. This corresponds to the equivalent dark current of 0.4mA.
Matt has finished the PCB layout. We will order small first batches, and stuff it for the test. Some of these will be the 40m green PD.
A new library part was made for the single suspension controller (it was originally made from the c1scx controller), using the following procedure:
Once the new sus_single_control library part was made and the library was committed to the cds_user_apps repo, I replaced all sus controller subsystems with this new part, in:
All models were rebuild, installed, and tested, and everything seems to be working fine.
CDS changed the suffix for all aquired channel names from _DAQ to _DQ. When we rebuilt the sus models, described in the previous log, the channel names were changed and consequently the channel files were completely rewritten.
To fix the issue, the latest archived channel file was copied back into the chans directory, and the suffixes were changed, as so:
cp archive/C1SUS_110602_155403.ini C1SUS.ini
sed -i 's/DAQ/DQ/g' C1SUS.ini
We then restarted the models and the framebuilder.
The full characterization of REFL11 is found in the PDF.
Resonance at 11.062MHz
Q of 15.5, transimpedance 4.1kOhm
shotnoise intercept current = 0.12mA (i.e. current noise of 6pA/rtHz)
Notch at 22.181MHz
Q of 28.0, transimpedance 23 Ohm
Notch at 55.589MHz
Q of 38.3, transimpedance 56 Ohm
The full characterization of POP55 is found in the PDF.
Resonance at 54.49MHz
Q of 2.5, transimpedance 241Ohm
shotnoise intercept current = 4.2mA (i.e. current noise of 37pA/rtHz)
Notch at 11.23MHz
Q of 2.4, transimpedance 6.2 Ohm
Notch at 110.80MHz
Q of 53.8, transimpedance 13.03 Ohm
AA filter box was removed and modified at 1Y7 today. The -5V power supply was current limited when I plugged it back in. It was removed for medical attention.
NO PEM channels available! because of this.
(continuation of this)
Here are the transfer function and noise plots of the seismometer box, using the op amps that are actually indicated on the original plan (THS4131, AD826). I added them to the LISO op amp library (can be found in /cvs/cds/caltech/apps/linux64/liso/filter/opamp.lib)
Next step is to compare the noise graph below to the seismic noise curve of the interferometer to verify that the seismometer box configuration won't affect the curve...
I've finished tuning POY11 and it is now sitting on top of the analyzer waiting for Koji to test its noise.
The full characterization of POY11 is found in the PDF.
Resonance at 11.03MHz
Q of 7.6, transimpedance 1.98kOhm
shotnoise intercept current = 0.17mA (i.e. current noise of 7pA/rtHz)
Notch at 21.99MHz
Q of 56.2, transimpedance 35.51 Ohm
Notch at 55.20MHz
Q of 48.5, transimpedance 37.5 Ohm
D68L8EX-850Hz filter chips were removed and bypassed-shorted as Rana's entry on March 17, 2006 in old elog.
This unit is still has a short somewhere.
Today Joe and I undertook a FULL rebuild of all front end systems with the head of the 2.1 branch of the RCG. Here is the full report of what we did:
--- Makefile (revision 2451)+++ Makefile (working copy)@@ -346,7 +346,7 @@ #MDL_MODELS = x1cdst1 x1isiham x1isiitmx x1iss x1lsc x1omc1 x1psl x1susetmx x1susetmy x1susitmx x1susitmy x1susquad1 x1susquad2 x1susquad3 x1susquad4 x1x12 x1x13 x1x14 x1x15 x1x16 x1x20 x1x21 x1x22 x1x23 #MDL_MODELS = $(wildcard src/epics/simLink/l1*.mdl)-MDL_MODELS = $(shell cd src/epics/simLink; ls m1*.mdl | sed 's/.mdl//')+MDL_MODELS = $(shell cd src/epics/simLink; ls c1*.mdl | sed 's/.mdl//') World: $(MDL_MODELS) showWorld:
cd src/gdsmakecp awgtpman /opt/rtcds/caltech/c1/target/gds/bin
The c1iscex models (c1x01 and c1scx) did not come back up. c1x01 was running long on every cycle, until the model crashed and brought down the computer. After many hours, and with Alex's help, we managed to track down the issue to a patch from Rolf at r2361. The code included in that patch should have been wrapped in an "#ifndef RFM_DIRECT_READ". This was fixed and committed to branches/branch-2.1 at r2460 and to trunk at r2461.
Everything is now green, and things seem to be working. Mode cleaner is locked. X arm locked.
Some weeks ago, Joe, Jamie, and I reworked the ETMY controls.
Today we found that the model rebuilds and BURT restores have conspired to put the SUS damping into a bad state.
1) The FM1 files in the XXSEN modules should switch the analog shadow sensor whitening. I found today that, at least on ETMY and ETMX, they do nothing. This needs to be fixed before we can use the suspensions.
2) I found all of the 3:30 and cts2um buttons OFF AGAIN. There's something certainly wrong with the way the models are being built or BURTed. All of our suspension tuning work is being lost as a consequence. We (Joe and Jamie) need to learn to use CONLOG and check that the system is not in a nonsense state after rebuilds. Just because the monitors have lights and the MEDM values are fluctuating doesn't mean that "ITS WORKING". As a rule, when someone says "it seems to work", that basically means that they have no idea if anything is working.
3) We need a way to test that the CDS system is working...
Joe discovered today that ETMY in fact has no binary output module at all, so there is actually no digital control of the whitening filters at ETMY.
We suspect that the ETMY binary output module was maybe harvested to put in the LSC rack, but we're not sure.
We found a spare binary output adapter pcb, which I will try to assemble into a module to install in ETMY.
This does not explain what's going on with ETMX, though. ETMX has a binary output module, that appears to be properly hooked up. I'll try to debug what's going on there as well.
In the mean time, I've removed the ETMX binary output module to use as a reference for putting together another identical module for ETMY.
Computar 75-12.5 zooms were installed for closer look at the resonant spots. Their alignment and focus needs more loving adjustment.
Atm 1, ITMX ( it was 10-40 mm Tamron before )
Atm 2, ITMY ( it was 12mm wide angle showing the towers before )
The current status of the dither alignment system:
- Both Xarm and Yarm alignment are working. The scripts are: scripts/autoDither/alignX(Y). Each script sets up the respective arm, turns on the dither lines and servos for 66 sec, offloads the control signals to TM alignment biases and PZT sliders in case of Yarm, and to TM and BS alignment biases in case of Xarm, and finally turns off and clears the servo filters and turns off the dither lines.
- Jammie witnessed the final tests of both scripts - both X and Y arm power went up from 0.6-0.7 to close to 1 and the AS beam became symmetric. Also Jammie wanted me to leave the ETMY oplev in its current non-nominal but more stable state i.e. the oplev signals go to the ADC from the D010033 card not the D020432 one. The scripts can now run from the CONFIGURE medm screen.
- Both arms use signals derived from modulating ITM and ETM in pitch and yaw dofs and demodulating the arm power (TRX or TRY) and the cavity length signal (AS55I). The Yarm actuation has 8 dofs - pitch and yaw of the ITM, ETM, and two input beam PZTs so all the sensed dofs are controlled. The Xarm actuation has only 6 dofs - pitch and yaw of the ITM, ETM, and BS. The Xarm servo is set up to servo the beam position on the ETMX and the relative alignment of the cavity and the input beam. The ITMX spot position is unconstrained and provides the null test. The residual displacement on the ITMX is 0.2-0.3 mm in yaw and 0.9-1.0 mm in pitch. The I phases of the beam centering lockins, which are also the error points of corresponding DOF filters, are calibrated in mm by unbalancing the TM coils by known amount. The attached snap shot of the medm screen now has both X and Y arm calibrated beam spot positions and uncalibrated input beam indicators. The input beam angle and position signals can/should be calibrated by tapping the signals digitally and applying the proper matrix transformation - this will require the model change.
- Currently there is no lock loss catching in the model. We should add a trigger on arm power (or an equivalent mechanism) to turn off the inputs to prevent the spurious inputs.
I focused these lenses so that we could get a clean image of the mirrors and the OSEMs.
Our goal is to have an image where the optic diameter almost fills the entire monitor. We want the focus to be adjusted for the YAG beam (which is almost the same as focusing for the OSEMs). This will NOT produce a nice image of the cage using visible light, but that is just fine.
When Justin Garofoli was here he found a nice lens combo that did the job, so if anyone can find his old email or elog, lets just go back to that.
For now, we do not need a camera/lens system to focus very tightly on the center of the optic.