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Entry  Wed Jun 13 02:11:59 2012, yuta, Update, Green Locking, my first modescan (sort of) modescan20120612_1.png
    Reply  Wed Jun 13 02:24:02 2012, rana, Update, Green Locking, my first modescan (sort of) 
       Reply  Wed Jun 13 03:03:38 2012, yuta, Update, Green Locking, my first modescan (sort of) 
          Reply  Wed Jun 13 11:10:56 2012, rana, Update, Green Locking, my first modescan (sort of) 
Message ID: 6812     Entry time: Wed Jun 13 03:03:38 2012     In reply to: 6811     Reply to this: 6813
Author: yuta 
Type: Update 
Category: Green Locking 
Subject: my first modescan (sort of) 

Linear range df of the delay line technique is about df ~ c/(2D). So, the linear range for the fine signal(delay line length D=30m) is about 5 MHz.
Arm cavity FSR = c/(2L) = 3.7 MHz.
So, I think we need phase shifting to do mode scan for more than 2 FSRs by holding the arm length finely with fine servo.
For the coarse (D=1.5m), the linear range is about 100 MHz, so if we can do mode scan using coarse servo, it is OK.

In any case, I think it is nice to have linear signal with fixed slope even if we don't adjust the phase every time.

Quote:

 That sounds goofy.

With the delay line technique, you can get a linear signal over 50 MHz with no phase shifting. What is with all this I/Q stuff?

 

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