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40m Log |
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Tue Feb 2 18:35:47 2016, gautam, Update, Green Locking, Lightwave NPRO moved from PSL table to SP table
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Tue Feb 2 18:54:02 2016, Koji, Update, Green Locking, Lightwave NPRO moved from PSL table to SP table
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Wed Feb 3 23:23:47 2016, gautam, Update, Green Locking, Lightwave NPRO moved from PSL table to SP table 
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Thu Feb 4 09:16:46 2016, Koji, Update, Green Locking, Lightwave NPRO moved from PSL table to SP table
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Fri Feb 5 00:23:01 2016, gautam, Update, Green Locking, Lightwave NPRO moved from PSL table to SP table   
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Fri Feb 5 16:50:24 2016, gautam, Update, Green Locking, First pass at mode-matching   
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Mon Feb 8 15:36:37 2016, gautam, Update, Green Locking, Alternative mode-matching scheme
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Tue Feb 9 04:37:10 2016, ericq, Update, Green Locking, Laser swap initiated
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Tue Feb 9 11:49:47 2016, gautam, Update, Green Locking, Laser swap initiated
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Tue Feb 9 19:15:36 2016, gautam, Update, Green Locking, Laser swap - updates 
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Wed Feb 10 17:57:15 2016, gautam, Update, Green Locking, Laser swap - updates
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Fri Feb 12 17:05:40 2016, gautam, Update, Green Locking, Laser swap - green light recovered but no flashes in the arm
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Fri Feb 12 19:07:52 2016, Koji, Update, Green Locking, Laser swap - green light recovered but no flashes in the arm
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Fri Feb 19 00:42:19 2016, gautam, Update, Green Locking, Laser swap - beam ellipticity from laser?  
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Mon Feb 22 13:56:52 2016, gautam, Update, Green Locking, Laser swap -reflected beam from ETM aligned
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Tue Feb 23 23:01:16 2016, gautam, Update, Green Locking, Laser swap - Green PDH locking 
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Wed Feb 24 19:29:13 2016, gautam, Update, Green Locking, Laser swap - Green PDH locked
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Fri Feb 26 01:52:44 2016, gautam, Update, Green Locking, Laser swap - Green PDH OLTF
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Mon Feb 29 17:17:26 2016, gautam, Update, Green Locking, Laser swap - still no green beatnote
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Wed Mar 2 17:42:19 2016, gautam, Update, Green Locking, Laser swap - some progress
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Thu Mar 3 01:25:50 2016, gautam, Update, Green Locking, Laser swap - 2 IR + 1 green beatnotes found
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Fri Mar 4 01:11:41 2016, gautam, Update, Green Locking, Laser swap - both green beatnotes found
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Sat Mar 5 23:31:01 2016, gautam, Update, Green Locking, Laser swap - some updates    
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Mon Mar 7 23:51:36 2016, gautam, Update, Green Locking, Laser swap - some improvement   
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Tue Mar 8 18:22:20 2016, rana, Update, Green Locking, Laser swap - some improvement
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Message ID: 11983
Entry time: Tue Feb 9 11:49:47 2016
In reply to: 11982
Reply to this: 11984
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Author: |
gautam |
Type: |
Update |
Category: |
Green Locking |
Subject: |
Laser swap initiated |
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Steve pointed me to an old elog by Zach where he had measured the waist of the 1W Innolight NPRO. I ran a la mode with these parameters (and the original optics in their original positions prior to last night's activities), and the result is in reasonably good agreement (see Attachment #1) with my initial target waist of 35 um at the center of the doubling oven (which I presume coincides with the center of the doubling crystal). The small discrepancy could be due to errors in position measurement (which I did by eye with a tape measure) or because I did not consider the Faraday in the a la mode calculation. However, I wonder why this value of 35 um was chosen? In this elog, Kiwamu has determined the optimal waist size to be 50um at the center of the doubling crystal. Nevertheless, as per his calculations, the doubling efficiency should be non-zero (about 1% lower than the optimum conversion efficiency) at 35um or 70um, so we should be able to see some green light as long as we are in this fairly large range. So perhaps the fact that we aren't seeing any green light is down to sub-optimal alignment? I don't think there is a threshold power for SHG as such, its just that with lower input power we expect less green light - in any case, 200mW should be producing some green light... From what I could gather from a bunch of old elogs by Aidan, the Raicol PPKPT crystals have dimension 1mm x 1mm x 30mm (long axis along beam propagation), so there isn't a whole lot of room for error perpendicular to the direction of propagation... I wonder if it is possible, for the initial alignment, to have the top cover of the doubling oven open so that we can be sure we are hitting the crystal? |
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