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Entry  Wed Mar 30 19:43:33 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching 
    Reply  Wed Mar 30 19:54:19 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching laser_output_non_circular.png
       Reply  Wed Mar 30 20:08:34 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching Beam_Matching_02c_Vertical.pngBeam_Matching_02c_Horizontal.png
          Reply  Wed Mar 30 20:14:17 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching 
             Reply  Wed Mar 30 20:31:30 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching 
                Reply  Wed Mar 30 20:50:43 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching After_Faraday.pngAfter_Faraday_and_Rotated_Lens.png
                   Reply  Wed Mar 30 21:21:15 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching Oven_Lens_Solution_66mm.pngMatching_Into_Green_Oven_zoomed_out.pngMatching_Into_Green_Oven_zoomed_in.png
                      Reply  Thu Mar 31 02:59:49 2011, Koji, Configuration, Green Locking, The wonderful world of mode-matching 
                         Reply  Thu Mar 31 14:10:00 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching P3310028.JPGP3310029.JPG
                         Reply  Thu Mar 31 15:23:14 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching Zoomed_out_fitting01.pngZoomed_in_fitting01.png
                            Reply  Mon Apr 4 14:20:32 2011, Bryan, Configuration, Green Locking, The wonderful world of mode-matching Waist_Fits_from_laser.pngWaist_Fits_Bench_Position.png
Message ID: 4465     Entry time: Wed Mar 30 19:54:19 2011     In reply to: 4464     Reply to this: 4466
Author: Bryan 
Type: Configuration 
Category: Green Locking 
Subject: The wonderful world of mode-matching 

RIght! Overview out of the way - now comes the trivial first bit

 

Step 1: Beam out of the laser - this will be tricky, but we'll see what we can actually measure in this set-up. Can't get the Beamscan head any closer to the laser and using a lambda/2 plate + polariser to control power until the Faraday isolator is in place. Using 1 inch separation holes as reference points for now - need better resolution later, but this is fine for now and gives an idea of where things need to go on the bench. The beam is aligned to the 3rd row up (T) for all measurements, the Beamscan spits out diameters (measuring only the 13.5% values) so convert as required to beam radius and the beam is checked to ensure a reasonable Gaussian profile throughout.

 

Position A1_13.5%_width A2_13.5%_width

(bench) (um mean) (um mean)

32 2166.1 1612.5

31 2283.4 1708.3

30 2416.1 1803.2

29 2547.5 1891.4

27 2860.1 2070.3

26 2930.2 2154.4

25 3074.4 2254.0

24 3207.0 2339.4

 

OK. As expected, this measurement is in the linear region of the beampath - i.e. not close to the  waist position and beyond the Rayleigh length) so it pretty much looks like two straight lines. There's no easy way to get into the path closer to the laser, so reckon we'll just need to infer back from the waist after we get a lens in there. Attached the plot, but about all you really need to get from this is that the beam out of the laser is very astigmatic and that the vertical axis expands faster than the horizontal.

Not terribly exciting, but have to start somewhere.

 

laser_output_non_circular.png

 

 

 

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