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Entry  Thu Mar 4 19:44:08 2010, Tara Chalermsongsak, Laser, RC noise, Noise from VCO Noise20100304.jpg
    Reply  Fri Mar 5 00:34:09 2010, Frank, Laser, RC noise, Noise from VCO 
       Reply  Fri Mar 5 14:40:21 2010, Frank, Laser, RC noise, Noise from VCO irf2023_@80Mhz.png
Message ID: 86     Entry time: Thu Mar 4 19:44:08 2010     Reply to this: 87
Author: Tara Chalermsongsak 
Type: Laser 
Category: RC noise 
Subject: Noise from VCO 

VCO frequency noise is measured. V input is 4.7 Volt. The signal output from the VCO (which controls the AOM) is mixed with signal from ifr2023 at ~80MHz. The demodulated signal

is then fed to SR560. Gain setting is 5 x10^3, low pass at 1Hz. The output signal is split into two. One is sent back to ifr2023 for freq modulation, another one is fed to the spectrum analyzer. The voltage output is

then converted to frequency by calibration from last week (0.714 MHz/V).

The plot shows frequncy noise from:

1: function generator (ifr2023) in brown

2: VCO,  in pink

3&4 Frank's RC noise data from FEB09, in red and blue

5:  RCnoise from beat measurment, in green

6: estimated noise

 

VCO seems to limit our noise at f=100Hz and higher/

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