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Entry  Tue Dec 4 19:34:22 2018, awade, DailyProgress, WOPO, Diabolo 532 nm power drop and retuning 18-12-04_DiaboloInside_annotate.jpegplot20181204_DiaboloSHGRaligned1064nm.pdfplot20181204_DiaboloSHGRErrSig.pdf20181204_RetuneDiaboloSHGAlignment.zip
    Reply  Thu Dec 6 20:04:50 2018, awade, DailyProgress, WOPO, Diabolo 532 nm power drop and retuning 
       Reply  Fri Dec 7 20:31:06 2018, awade, DailyProgress, WOPO, Diabolo: cleaning dust out of SHG unit, self heating issues 18-12-07_20-06-46_4774.jpg18-12-07_20-06-58_4776.jpg18-12-07_20-07-44_4780.jpgIMG_4785.JPGIMG_4766.MOV
          Reply  Thu Dec 13 14:01:13 2018, awade, DailyProgress, WOPO, Diabolo: contacted coherent 
             Reply  Thu Dec 13 16:24:06 2018, awade, DailyProgress, WOPO, Diabolo: baseline numbers for coherent plot20181218_PhaseMatchingCurveFastScanDiaboloSHG.pdf20181213_SHGScanWithLNTempTuning.zip
                Reply  Wed Dec 19 16:48:18 2018, awade, DailyProgress, WOPO, Diabolo: baseline numbers for coherent 
                   Reply  Thu Dec 20 19:20:50 2018, awade, DailyProgress, WOPO, Diabolo: trialing SHG oven set temperature points to see if there is a maxima when locked plot20181220_SHGLockedOutputVsOvenSetpointTemperature.pdf20181220_SHGLockedPowerVsSetPointTemp.zip
                      Reply  Fri Dec 21 15:33:26 2018, Koji, DailyProgress, WOPO, Diabolo: trialing SHG oven set temperature points to see if there is a maxima when locked 
                         Reply  Fri Dec 21 15:51:27 2018, awade, DailyProgress, WOPO, Diabolo: trialing SHG oven set temperature points to see if there is a maxima when locked 
                      Reply  Mon Dec 24 10:08:49 2018, awade, DailyProgress, WOPO, Diabolo: back to power with deliberate pre-misalignment 18-12-21_22-04-30_4812.jpg18-12-21_22-04-54_4813.jpg18-12-21_22-07-55_4814.jpg
                         Reply  Mon Dec 24 12:07:18 2018, Koji, DailyProgress, WOPO, Diabolo: back to power with deliberate pre-misalignment 
Message ID: 2283     Entry time: Wed Dec 19 16:48:18 2018     In reply to: 2281     Reply to this: 2284
Author: awade 
Type: DailyProgress 
Category: WOPO 
Subject: Diabolo: baseline numbers for coherent 

Contact with Coherent re Diabolo

I got in contact with Coherent they have provided some instructions on aligning the laser cavity, something I've already attempted and knew how to do.  For future reference I've attached the instructions on the wiki (they are confidential): they can be found attached HERE.

More details on Diabolo manual and documentation can be found on the Manuals-And-Datasheets ATF wiki page.  

Temperature tuning

I've been attempting to find sweet spot for phase matching temperature between oven and self heating.  The FWHM of the phase matching temperature of the SHG lithium niobate crystal appears to be on the order of about 0.2 C which makes it quite narrow.  Given there is quite a bit of self heating in the cavity when it is locked up, it would be very easy to miss the correct temperature when setting the crystal's oven set point.

Koji/rana has suggested turning down the laser power, locking and then gradually tuning the oven temperature to get to ideal set point as we increase power.  I've attempted this and found that the autolock requires some minimum amount of laser power to engage.  I opened up the controller box and traced a few things through the PCBs, but it is not immediately apparent which pot adjusts the autotune threshold value for power.  I've emailed the contact at Coherent and they are making inquires to see if they can tell me what to adjust to lower this threshold manually.  For now I will attempt a few more full power locks at carefully spaced values of crystal temperature to see if I am able to happen upon a sweet spot.

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