I've been in and out of the PCAL lab trying to test this new laser from CrystaLaser this week.
Thankfully I was able to connect with Dr. Jin out there and they steered me in the right direction.

When I first tried to test it I had the wrong power supply that couldn't keep up with current demands. As noted by the faintly lit current limit LED. The laser needs around 1.3 to 1.5 Amps to start up.

I've been finding that I had a fairly consistant TEM01 mode coming out of the laser it's self. I'm certain that the laser's been jostled around during shipping. After a few emails with Dr. Jin about this, Jin was able to guide me towards easily tweaking the laser to get a much better beam out of this laser head.

I was able to set up a beam profiler to do some preliminary beam profile data from a scanning slit profiler that was getting 1% of the beam out of a 1% beam splitter. 
the other 99% was sent to a power meter. 

Subject laser:
Make: CrystaLaser. 
Model: CL1047-2W0-ULG
Serial number: SN 460308-9464 
Gov #: G33348
Max power: 1.92W (measured after a 1% beam spliter.)
More beam profiler info comming soon. 
  

TITLE: 10/03 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: We're still having trouble at TR_CARM. There was some weirdness with PR2 then SRM, I'm leaving IFO in down for the weekend.
LOG:                                                                                                                                                                                                                                             

~23:30 UTC While I was locking DRMI to then touch up SRM, after doing the same for PRMI and PRM, all of M3 and M1 LF RT immediately saturated with a huge signal coming from ISC L. Looking at the LSC SRC1 filter bank, we could see that the error signal could not reach positive 800 due to the offset of -800. Keita then turned off FM4 and the saturations stopped, turning it back on brought them right back. We were able to turn that filter off and on while seemingly remaining locked (if it was a real lock, heres  a plot of the sidebands power during PRMI then the subsequent DRMI, the levels are about the same) on DRMI 1f despite having no length feedback. The SRM alignment was likely bad, it "held" until I manually brought us down with ISC_LOCK.

TITLE: 10/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC

STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:

Today there was continued work looking at the lead-up to the CARM TO TR step for ISC LOCK.  For the most part DRMI reacquisition was fairly easy (Sheila alog-ed about a random PR3 move which was odd.) 

Toward the end of the shift, OM3's heater was increased from 1.0 to 4.0W for over the weekend.
LOG:

• 1437-1536 Manual Initial Alignment
• 1700-1740 EQ Mode Activated (M5.8 Russia)
• 1715-1829 CHETA laser hazard work (sophie)
• 1723-1732:  PRMI taking a while to lock, so touched up PRM & BS via PRX + MICH DARK align ifo states. (PRM moved the most (in pit), not much though); then back to PRMI_LOCKED.
• 1850-1925 Working on CrystalLaser (tony)
• 1915-1933 IR cavity alignment for PRM, BS, SRM again.
• 1948 While waiting for DRMI to lock, flashes all of sudden stopped.  RyanC noticed it was due to 
• 2100-2205 OMC dcpd function generator set-up in lvea, WP13679 (keita,alex)
  • But mentioned going out later.
• 2122-2209 Recording change made with  PCal CrystalLaser (tony, ryanC)
• 2312 Sheila requested us to take SR3's heater to 4.0 W (from 1.0W) for over the weekend.

Daniel, Sheila, Corey, Keita

Here are some comparisons of power build ups on POPAIR B:

Tony and Ryan Crouch found time for PRMI + DRMI without the arms from before the BS swap using state counter, they are writting an alog about that. 

We seem to now get more of an increase in build ups that we would expect from locking the arms, and we have more light on the diode than in O4.  We do not know if we might have had clipping in this in air path during O4. 

Some changes:

• leaving SRCL offset on for TR_CARM transition seems to help.  I have commented out line 1163 in ISC_DRMI, so the SRCL offset will stay on until we manually turn it off.  It may be better to use a larger offset, like -1200 counts.  
• With DRMI locked, after Corey fine tuned the alignment, we moved the SRCL offset around.  POP90 changes with the SRCL offset as shown in the attached screenshot. It seems like we need to keep POP18 above 200 counts to have a smooth time with the TR_CARM transition. 
• Moving the ALS COMM VCO a bit closer before starting the TR_CARM transition seems to help (-100 Hz offset instead of -200 Hz).  (this change is in lscparams).  
• PR3 jumped, 92170.  After this Corey put it back according to the top mass osems and then realigned MICH and PRX.  After this the build ups in DRMI were lower, but they were also more stable and we didn't have as much mode hopping.  
• We were able to go to the start_TR_CARM state, and with the above changes the guardian was able to once do this without intervention.  This means we can servo the arm transmitted powers, but something seems not stable here.  
• I tried to measure the TR_CARM loop gain, but the coherence is too low with the settings in our usual template (userapps/lsc/CARM/TR_CARM has excitation amplitude of 1).  I increased the loop gain by putting a 3 in TR_CARM where there is normally a 1, and increased the amplitude to 10.  We lost lock for an unknown reason, not the measurement.
• locking PRMI and DRMI has been slow.  Here is an old alog about the trigger levels 44348  When we ahave DRMI locked the MICH TRIG MONITOR (POP 18 norm) is around 100, based on this old alog I manually changed the trigger threshold to 27 and this seemed to help PRMI lock.  I've only tried this once and didn't put it in the guardian.  
• We are able to to strat_TR_CARM, with the SRCL offset on, then add a factor of 3 gain (in the input matrix or TR_CARM) and then step the TR_CARM offset to -0.8 without looseing lock.  I was only able to get a poor coherence measurement but it seems like this may have a ugf close to 100 Hz.  I do not understand why this is not stable, and stepping down the ALS gain seems to cause locklosses or large glitches.  

If anyone is looking for times that the PRMI is locked and the ALS COMM was Down, then Ryan C. Went ahead and found all those times for ya.
please see the following attached text files.

PRMI35-Locked_NoALS100_preBS.txt is a list of GPS time when H1:GRD-ISC_DRMI_STATE_N= 35 (in a PRMI state) AND H1:GRD-ALS_COMM_STATE_N = 100 (the Down State)

This was created via a tool called statecounter found in /ligo/gitcommon/statecounter. 

To run this particular command we used the following:
python3 statecounter.py -chan "H1:GRD-ISC_DRMI_STATE_N H1:GRD-ALS_COMM_STATE_N " -operator "==" -value "35 100" -trend "m-trend" -gpsstart "1198828818" -gpsstop "1459036818" --host h1daqnds0 -port 8088 -output "/ligo/home/anthony.sanchez/Documents/TonysOps/StateCounterResearch/PRMI35-Locked-NoALS100preBS.txt"

I also did the same for a bunch of DRMI states too which are included below.

Thanks for your help dividing and conquering Ryan C!
Thanks for the challenging question Sheila!

The CHETA X arm table telescope was fully aligned as described in gitlab. The performance of the telescope was determined by profiling the beam after L2 and calculating the complex q factor. The profile was measured using the nanoscan beam profiler over a 55cm range between M4 and M5.

This unit was profiled twice the first with a slight angle on L1 to prevent back reflection and then with a reduced angle to determine if this was detrimentally effecting the beam propogation. A non-linear fit was used in both cases to find the q factor which was propogated to the ITM to determine ITM beamsize. Both results show the horizontal axis have a large deviation from the expected q factor and the beamsize at the ITM is reduced by ≈35% and reducing the angle had a minimal effect.

Unit 0922 is noticibly non gaussian, screenshot attached, which we believe is consistent with what was observed by thorlabs and is indicated in a paper datasheet shipped to us with the unit. We believe this may be contributing to the deviation from the model.

Ryan Crouch, Corey, Sheila, Keita

After Corey aliged PRMI, and was waiting for it to lock, we suddenly lost the flashes in PRMI.  Ryan Crouch noted that PR3 moved, indeed there is a jump in all 6 top mass osems at the time that we lost the flashes.  Perhaps we need to investigate these electronics.

J. Kissel

As I'm building up my understanding the ISI system -- in order to eventually understand how to compare it to the SPI signals -- I found one thing I didn't like. 
When looking at the ISI data offline, we're typically looking at DQ channels -- i.e. those versions of test points that are stored in the frames -- so that we don't have to wait so long to gather data down to 1 [mHz]. 

Fine.

The native rate of the ISI front-end models is 4096 [Hz], so storing every interesting channel at the full data rate would be too much. As such, we down-sample some channels before storage.
Fine.

Of course, down-sampling requires a digital anti-aliasing filter, often referred to as the "DAQ down-sampling filter."
These are defined in T1600059 and the front-end in terms of "factor-of-reduction from native sampling frequency," e.g. if the native rate of the model is 4096 [Hz] and you chose to store the channel at 2048 [Hz], then you apply the "2x" filter. 

We store the inertial sensors, input to the blends e.g. H1:ISI-HAM2_BLND_GS13X_IN1_DQ at 4096 [Hz] so there's no downsampling filter involved.
Long ago, we decided that down-sampling the CPS to 512 [Hz] is good.
4096 / 512 = 8x.

But there's something very wrong with the 8x down sampling filter in the ISI system.
    (a) The DC magnitude of the transfer function between raw and DQ channel is 0.9954; i.e. a 0.5% gain loss.
    (b) The filter's ripple peaks at ~70 Hz with a magnitude of 1.0386.
    (c) The phase loss at 10 Hz is -9.1 [deg].

It's difficult to tell from the plots in T1600059 what the magnitude is doing, but I thought that these filters were normalized such that *either* the DC magnitude was 1.0, or the peak of the ripple is 1.0. Neither is true.
But, far worse -- the 8x filter phase in the design doc says its only losing -0.5 [deg] of phase at 10 [Hz].

We should fix the issue with the filter, and/or use a higher down-sampling rate.

If there's confusing stuff like this happening at such a base level, it makes it that much harder to interpret / compare the already confusing sensor signals.

The CRS laser is now on its final hardware, with TEC and power control running through CDS and a new guardian. Damping works, but still needs some attention. Readout noise is now x2-3 times lower thanks to the new TIA. 

• Cabling and interface chassis (92108, 92097): We pulled two new DB25 cables (CRS LASER 4/5) from TCS-R2 to SEI-C1 and installed the final interface chassis, D2400073. Wiring redlines were posted at D2600186. The higher TIA gain from the new chassis (15.8k vs 4.99k V/A) improves the tilt readout noise by about 2-3 accross the spectrum (light green) compared to our best reference (dark green).
• Model changes (92153): We added a LASER subsystem to CRSPROC with laser monitors, a frontend TEC loop, and a DRIVE bank for laser power, plus a VEL filter module. Channels are H1:ISI-HAM3_CRSRY_LASER_*, and documented in E2600265-v2. Moving forward, I would also like to propose adding an ADC and a DAC to the ham23 IO, dedicated to CRS/SPI. Even though the current scheme works, having the CRS LASER running in HAM16 is not optimal, and increases fault probabilty.
• Damping (92116): All cap plates actuate. The damping loop works with its -2e9 gain now built into dampBP, so it engages with a gain of +1. One HEPI AI channel (dac0 chan 14, U26) is weak, so we're holding off on the Q measurement until that chassis is replaced.
• Laser driver and TEC (92137): We installed the final laser driver, D1500207, and commissioned the CDS TEC loop. Power and noise are unchanged, and the Thorlabs TEC is now unplugged from the AC mains (left in the LVEA for now).
• Guardian (92152): The new CRS_LASER guardian (LASER_ON/LASER_OFF) makes sure the TEC is engaged before the laser turns on, and there's a new laser MEDM screen. Details are in T2600470.
• Power transients : With the new monitor channels (HOQI power and Laser power), we observe what looks like mode hoping (also observed here by Shoshana), see attached screenshot. The power transients happen at the same time on both hoqis, and are also measured by the PD in the laser. Once the thermal state of the laser is stabilized, we can try to move the TEC setpoint around to try park the laser away from a mode hoping region, like Shoshana did. We can also try to add an optical isolator inline, in case it comes from some backreflection in the fiber. Touching the fiber also creates transients in the power channels. It seems that this mode hoping makes the readout noise spectrum breathe, so reducing it might improve the noise even more. 

Left to do: replace the AI chassis and measure the ring down Q, update the SOP (M2600128), finish Technical note T2600471, create the CRS_STAT guardian, monitor the TEC stability (+ try to find a mode hop free region), record new chassis serial numbers and post photos.

With return to locking this week, here's a note on Initial Alignment steps without using WFS (please add comments if I"m missing anything or have something wrong).

• MANUAL INITIAL ALIGNMENT (for ISC_LOCK)  
  • Green Arms via ALS_[X/Y]ARM grd nodes:  Y-arm had decent flashes, but had to run a Scan Alignment, but both arms completed INITIAL ALIGNMENT OFFLOADED for alsx & alsy.
  • Now use ALIGN_IFO
  • Xarm IR:  Went to WFS CENTERING XARM:  LSC TR X was hovering around 1, so moved on
    • QUES:  What if TR X is low at this point, adjust ETMx/TMSx?
  • PRX:  PRX LOCKED state and tweaked PRM to maximize AS_A_DC (started at 3.1 & up to 3.65)
  • MICH DARK:  ACQUIRE_MICH_DARK & moved the BS to make AS AIR darker & minimize AS_A_DC
  • SRC:  Had some guardian troubles with SRYLOCKED yesterday/today; sheila looking into this  
    • completed OFFLOAD SR2 ALIGNMENT, & then moved back to...
    • PREP FOR SRY and ACQUIRE_SRY states---
      • Adjust SRM to get better flashes on AS_A_DC (highs higher/lows lower)
      • Once better, go to SRY_LOCKED, continue to adjust SRM if not locked.  Once locked, touch up SRM to maximize AS_A_DC.
• Alignment Done & Moved on to Locking
  • ISC LOCK:  INIT & move on to PRMI ASC
    • Where ASC controls BS (mostly), but one still has to touch up PRM. Then moved on to DRMI
  • DRMI:  When DRMI locked, aimed for this:  (1) POP18 @210, and (2) POP90 @30 (with tweaks mostly from SRM)
    • Saw some of the BS Mode Hopping sheila mentioned which was observed yesterday, too.  (really see this with POP90, which would hop to negative values).  Worked on alignment touch up via (BS, PRM) 
• NEXT:  Plan is to continue progress getting past CARM to TR

J. Kissel

More operational checks: What happens to the SPI signal when the IMC loses lock? The MEAS IFO glitches and buzzes; the REF IFO remains constant. Maybe scattered light?

See three attached examples of the SPI IFO MEAS and REF A PD displacement and raw phase signals versus the IMC lock state and power at MC_TRANS.

J. Kissel

At 2026-10-02 16:11:50 UTC, I reset the phase unwrapping algorithm for the SPI. Jennie had just reset it last night at 2026-10-02 01:31:46 UTC and 01:31:49 UTC (LHO:92154), as we know we need to after shuttering and re-energizing the laser. Not sure if it needed now -- the attached trend shows there were no discontinuities, just slow drift away from 0 [nm] displacement readout -- but I did it anyway. Posting for posterity to gather statistics on how often we do this.

TITLE: 10/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.11 μm/s 
QUICK SUMMARY:

Looks like work will continue around the CARM TO TR state for H1 locking. ISC LOCK currently in PREP FOR LOCKING; will run a manual alignment (y-arm flashing is about 1.3 & x-arm is about 0.4).

TITLE: 10/02 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: Not much to report, there's an issue with the TR_CARM states to be further addressed tomorrow. Jim and Arnauld worked on some CRS damping.  ISC_LOCK is being held in down. Arnaud might touch the CRS a little more tonight.
LOG:                                                                                                                                                                           

00:15 UTC A few HAM3 ISI trips from CRS testing

Travis, Gerardo, Jordan, Betsy, Tyler, Richard

This morning we proceeded with the manual opening of GV20. Tyler had made a nice support for the input shaft on the gearbox to stabilize it while rotating the handwheel. This worked great, no additional oil leaked out of the gearbox after installation.

We had left the valve soft closed overnight, so we started raising the valve at 10:41:59 Pacific by turning the handwheel counter clockwise, stopping every 50 turns to check the ballnut/shaft collar gap. No issues found.

At turn 370, we tested to see if the handwheel would be driven backwards by the weight of the gate. No backwheeling was present, so we continued raising the valve stopping every 50 turns to check ballnut/ball screw height. At turn 620 we decided to increase the interval between stoppages to 100 turns. After turn 1520, the top of the ball screw was about even with the top of the clutch body. At 1920, there was enough exposed ball screw to install the safety plate and the locking collars. Locking collars were torqued to 140 in-lbs. 

We then continued raising the valve 300 turns (2") at a time, adjusting the lock collars at each interval, until the medm screen showed green.

Final turn count: 7161

Final ball screw height, +37.75" from top of clutch body (open position/green on medm) Note: Height stamped on side actuator body read 37 7/8" for the open position.

The interlock pin was then set, and lock collars were moved to top of safety plate, and torqued to 140 in-lbs. The handwheel was left installed on the gearbox with a clamp on it to prevent rotation.

Full set of compiled notes/details will be posted to the DCC with noises/turn counts/timestamps/ball screw heights/etc.  

TITLE: 09/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: Tony
SHIFT SUMMARY:

DRMI locking work continued, but the afternoon focused on ETMx investigation/troubleshooting (look for an alog on this later).

The Relay Tube was opened up to the main volume (HAM7 & "downstream" remain isolated and pumping down).
LOG:

• All Day:  BT Enclosure patch work; just passed the +3km mark (randy)
• 1500-1540 Morning Alignment:  Started aligning of cavities noted in Elenna's alog notes);  Took ISC_LOCK to MANUAL_INTIAL_ALIGNMENT: 
  • Green Arms:  Used INIT_ALIGN & selected GREEN_ARMS_OFFLOADED
    • Y-arm had decent flashes, but X-arm was not as good--tried tweaking a little by hand but SCAN ALIGNMENT took over & finished the alignment.
• NOTE:  After Green Arms, used ALIGN_IFO to select different states for aligning other cavities
  • Xarm IR: (completed WFS CENTERING XARM)
    • When Elenna arrived, we checked this again at XARM_IR_LOCKED (I think this was at 1, so no changes made)
  • PRX: (completed WFS CENTERING PRX),
    • Elenna had me redo PRX alignment:  Since no WFS, because rfpds need to get rephased after DRMI work
    • Hand Tweaks:  Went to PRX_LOCKED & then tweaked PRM to maximize AS_A_DC
  • Mich Dark: (lockloss at MICH DARK ALIGN, so I skipped this after 2nd attempt). 
    • Hand Tweaks:  Then just tweaked BS by hand by taking to MICH DARK LOCKED and tweaking BS to optimize Dark spot for AS AIR (or minimize AS_A_DC)
  • SR Align: (This is when Elenna arrived and helped me)   edit:  (completed to PREP SRC ALIGN)
  • SRY:  Go to SRY_LOCKED
    • Hand Tweaks:  While locking, SRM tweaked-up fringes (highs high/low low) 
    • SRY locks and then continue SRM tweaks to maximize AS_A_DC
  • SR2 (completed OFFLOAD SR2 ALIGNMENT)
  • PRX Again:  Make sure PRM is tweaked up (with Elenna)
    • PRM used to maximize AS_A_DC
• 1500-1548 optics lab (kim)
• 1613-1825 spackle 2hrs (chris)
• 1600-1710 TCS Property sorting (tj,christina)
• 1749-1758 H2 room clean (kim)
• 1815-1845 checking on key for a door (tj,richard)
• 1846-1909 Connect Relay Tube to Main Volume (HAM7 will remain valved off to continue pumping down) [gerardo.jordan]
• 2101 Moving parts from Corner to H2 Bldg & MY (fil + marc joining)
• 2125 Plugging in cable at psl racks for JAC measurement; but it was already connected (sheila)

After the angle calibrations were applied to the SPI readout channels, I grabbed some data to check whether the SPI is roughly agreeing with the ISI sensors. I used the supersensor OUT channels for the ISI sensors (these are the signals behind the blending filters, before the summation for the blended supersensor). Screenshots from diaggui are attached.

For the differential X degree of freedom (SPI length), the visual agreement is remarkably good.

The optical lever (angle) measurements are harder to interpret. First of all, QPD A has an as-yet-unresolved noise issue, which Jennie is currently investigating. Aside from this, the results look very encouraging, since the CPS and GS13 at least somewhat agree with the SPI.

These spectra should be regarded as a first result, but not yet final. We will post a better analysis once the error has been resolved.

Note: If anyone has suggestions for which sensor channels would provide a better/more appropriate comparison than the supersensor OUT channels used here, please comment, your input is welcome.

J. Kissel, R. Short, J. Oberling

This is the first installment of aLOGs documenting the setup of a new stand-alone 1064 nm NPRO laser system whose current "end game" intent is to provide ~100 [mW] of fiber-coupled p-pol light to the SPI laser prep chassis.

Step 1: Gathering materials, find what optics / mounts we had vs. what would be need, and physically layout the plan.

Jason lets Ryan and I know that there are three NPROs in the optics lab, two of which are PSL spares that cannot be used. 
The remaining laser is S/N 1661, the laser used in the PSL during O3 which is *functional* but was briefly installed during O4 circa Fall/Winter 2024 then removed from use in the PSL because of reported glitching / incompatibility with the frequency stabilization servo (FSS) issues -- see the bottom of LHO:81391 for a nice summary, and LHO:81409 for record of its removal.

Inspired by the setup at Stanford Sina shared with us, we're looking to build up the following system to accomplish the goal:
    - NPRO (presumed to be elliptically polarized with Is / Ip = 5:1)
    - QWP (to linearize the polarization)
    - HWP1 (to rotate the polarization into horizontal)
    - FI (accepts horizontal linear polarization, to ensure back-reflections from down-stream components don't seed the NPRO causing glitches/mode hopes/frequency noise)
    - HWP2 (to rotate the FI output polarization into the desired amount of vertical polarization -- aka the desired amount p-polarization)
    - PBS (to filter out and dump the unneeded horizontal / s-pol light, and transmit the desired power of p-pol)
    - SM1 (one of two steering mirrors to align the beam into the fiber collimator)
    - L1 (the single-lens mode-matching solution to convert the NPRO beam into what the fiber collimator needs)
    - SM2 (two of two steering mirrors for alignment into the fiber collimator)
    - 50:50 PWR BS (45 [deg] AOI, optimized for p-pol; to provide a pick-off port for live power measurement)
    - Fiber Collimator

Ryan started with a 24" by 12" breadboard that was lying around in the optics lab. He build up a makeshift stand from three posts and dogs in the lower left corner such that the S/N 1661 NPRO projects the beam at 4" height. The 0.5" thick breadboard has a 1 inch hole pattern offset by 0.5" from the edges. I'll refer to this grid as having axes "m" and "n" where the m-axis are the "row" holes running from 0 to 23, and the "column" n-axis holes run from 0 to 11. I chose (m,n) breadboard coordinates so as to not confuse them with traditional beam profile coordinates of (z [propagation distance], x (transverse horizontal), y (transverse vertical)). 

Thus, the NPRO being in the "lower left" means it projects the beam along the m = 3 row, and the front face of the NPRO is sitting at n = 8. We'll call this beam position z = 0.

We then proceeded to gather as much as we could of optical components from the optics lab drawers, and ended up with this pictured preliminary version of the setup.

Step 2. Power up the NPRO.
Here's were we ran into our first snag. Normally, NPROs are paired/tuned with specific controller boxes. However, when Ryan turned on the S/N 1661 laser with the S/N 1661 control box, the crystal temperature readback reported the temperature was quickly, linearly rising well beyond the desired temperature of 24.7 [deg C]. At ~42 [deg C], (but still below the internal automatic watchdog threshold of 50 [deg C]), Ryan knew something was wrong and turned it all off. He repeated the turn on just in case, and it did the same.

After conversing with Jason, we figure it's good enough to run with one of the other controllers for now, and in the mean time figure out how what's wrong and repair the S/N 1661 controller.

So, we're running with the S/N 7974, and things seem fine. 
    Laser Diode Temp Setup:
        Diode 1 33.7 [deg C]
        Diode 2: 33.1 [deg C]
        Laser diode injection current readback 2.08 [A] (for both diodes)
    Crystal Temp setting is 24.7 [deg C]

We measured the output power*** with no optical elements at all as 1.820 +/- 0.005 W (not noisey, but a slow drift around).
Good enough! Onward and upward!

*** Power measured by ThorLabs power meter
	Model S302C
	SN 111149
	Sensing factor of 316.25 [mV/W]
	(last calibrated Feb 3 2012).