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Entry  Wed Nov 18 17:49:05 2020, Paco, DailyProgress, Optics, beam profiles 2020_11_18_ecdlprofile.png2020_11_18_mephistoprofile.png
    Reply  Mon Dec 21 16:35:14 2020, Anchal, DailyProgress, Optics, Took beam profile of laser right off the head LaserHeadBeamProfileAvg.pdfLaserHeadBeamProfileX.pdfLaserHeadBeamProfileY.pdf
       Reply  Tue Dec 22 15:54:03 2020, Anchal, DailyProgress, Optics, Took beam profile of near EOM area BeamProfileNearEOMAvg.pdf
          Reply  Mon Dec 28 15:51:51 2020, Anchal, DailyProgress, Optics, Mode matching solution for Cavity Solutions1-7merged.pdf
             Reply  Thu Dec 31 16:41:59 2020, Anchal, DailyProgress, Optics, Mode matching solution for Cavity Solutions.pdf
                Reply  Wed Jan 6 09:34:34 2021, Anchal, DailyProgress, Optics, Corrected analysis and found better solutions. Solutions.pdf
                   Reply  Fri Jan 8 17:00:26 2021, Anchal, DailyProgress, Optics, Included lens made by cavity input mirror and distrotion due to crystal Solutions.pdf
                   Reply  Fri Jan 8 17:17:19 2021, Anchal, DailyProgress, Optics, Included lens made by cavity input mirror and distrotion due to crystal Solutions.pdf
                      Reply  Tue Jan 26 11:33:32 2021, rana, DailyProgress, Optics, Included lens made by cavity input mirror and distrotion due to crystal 
                      Reply  Tue Jan 26 11:34:51 2021, rana, DailyProgress, Optics, Included lens made by cavity input mirror and distrotion due to crystal 
Message ID: 1864     Entry time: Wed Nov 18 17:49:05 2020     Reply to this: 1881
Author: Paco 
Type: DailyProgress 
Category: Optics 
Subject: beam profiles 

Used BeamR and WinCamD to profile the two light sources (ECDL and OPO pump) 

(1) ECDL; profile 19** nm beam after the aspheric lens. I guess we want this beam to be nominally collimated for optimal feedback with the Littrow-configured grating, so I recorded the 1/e^2 waists (x, y) as a function of longitudinal displacement. The result is attached below. Linear fits provide rough estimates for the beam divergences, giving 2.0 mrad along x (parallel to the table) and 1.2 mrad along y (normal to the table) suggesting some astigmatism which is common in high NA aspheric lenses. I inspected the distance from the aspheric lens to the SAF gain chip and measured ~ 2.0 mm (compared to the 1.99 mm working distance specified for this lens with NA=0.71). The SAF1900S specifies a beam divergence angle of 35 deg  (corresponding to NA=0.57), so there is room for improvement by tweaking the aspheric flexure alignment.

(2) NPRO; profile 1064 nm beam at low power (~10 mW) right after the head output. Having 10x more power made things way easier for this as compared to the ECDL, but the method was the same (record 1/e^2 waists as a function of longitudinal displacement). The result is attached below. Linear fits provide rough estimates for the beam divergences, giving 2.1 mrad along x, and 2.1 mrad along y. Here I grabbed the specified divergence of 2.3 mrad from a relatively old manual, and even drew the displaced waist profile (w0 = 160 um) which seemingly fit the profile, but the actual values may be different.

Attachment 1: 2020_11_18_ecdlprofile.png  55 kB  | Hide | Hide all
2020_11_18_ecdlprofile.png
Attachment 2: 2020_11_18_mephistoprofile.png  67 kB  | Hide | Hide all
2020_11_18_mephistoprofile.png
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