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Entry  Wed Oct 13 00:35:26 2010, kiwamu, Update, Green Locking, PSL beat note setup 
    Reply  Fri Oct 15 06:31:52 2010, kiwamu, Update, Green Locking, PSL beat note setup: part II 
Message ID: 3727     Entry time: Fri Oct 15 06:31:52 2010     In reply to: 3703
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: PSL beat note setup: part II 

 I made some KAIZENs (what does kaizen mean ? ) for the PSL green setup.

I replaced the lenses for the modematching of the two green lights at the PSL table, and the beams now look pretty identical.

Also I tuned the temperature setpoint of the doubling crystal and eventually the green light increased to 14 uW at the PSL table.

Once I finish the modification of the RFPD tomorrow, I am going to search for the beat note signal.

 


( details )

 - In-vac green mirrors

   I found one of the green steering mirror, which stands at the corner of the MC table, was clipping the green light.

  So I steered another mirror, which sends the beam to the clipping mirror after the downward periscope.

 I touched also the last steering mirror in the OMC chamber to correct the alignment.

 

 - temperature of the doubling crystal

   I took a quick temperature scan in order to find an optimum point for the crystal temperature.

  The scan was performed by just turning the heater off after I heated up the crystal up to 40 deg. 

  Using the NewPort power meter I found the optimum point around 37.3 deg. So I set the temperature to that point.

 

 - mode matching lenses

 As written in this entry , Kevin and I had put some lenses to make the two green beam almost the same size at the RFPD.

 But today while I was checking these mode-profiles by using a sensor card, I found they were not so matched.

 Therefore I replaced these lenses to match them more.

The idea of this replacement is t to let them have a long Rayleigh range, such that they can efficiently and easily interfere because of the flatness of their wave fronts along a distant.

 For the green light from the chamber, I put one more lens to form a Keplerian beam shrinker (see here about the Keplerian lens configuration).

 They look pretty identical now.

 

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