40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Fri Jul 29 16:25:06 2011, kiwamu, Update, ASC, beam axis and Y arm aligned 
    Reply  Sat Jul 30 06:24:06 2011, kiwamu, Update, ASC, Y arm ASS fixed 
       Reply  Sat Jul 30 21:04:23 2011, kiwamu, Update, ASC, Y arm ASS fixed 
       Reply  Sun Jul 31 00:05:52 2011, kiwamu, Update, LSC, script for loss measurement : modified 
          Reply  Sun Jul 31 22:35:35 2011, kiwamu, Update, LSC, arm loss measurement : done 
             Reply  Wed Sep 7 16:21:35 2011, kiwamu, Update, LSC, arm loss measurement : resluts Yarmloss.pngXarmloss.png
                Reply  Wed Sep 7 17:28:41 2011, kiwamu, Update, LSC, X arm loss measurement : not good Xarmlossmeasurement.png
Message ID: 5360     Entry time: Wed Sep 7 17:28:41 2011     In reply to: 5359
Author: kiwamu 
Type: Update 
Category: LSC 
Subject: X arm loss measurement : not good 

The measurement itself wasn't good.

I looked at the full 2 kHz data which was taken during the time when I was running the arm loss script on the X arm.

The plot below shows the raw data. The X arm was locked and unlocked sequentially several times.

The ASDC power didn't show a significant difference between the state where it is locked and unlocked.

I am not sure why, but It could be because of a misalginment or some kind of mode-mismatching, which can decrease the coupling efficiency of light going into the cavity.

 

Xarmlossmeasurement.png

 

(some notes)

The raw data were analyzed.

I split the ASDC data into two data, (1) low power state, when the cavity is locked (2) high power state, when the cavity is unlocked.

Then each state was averaged to estimate the averaged ASDC power in each case.

The number I obtained are :

    ASDC when X arm was locked = 54.77755 cnts

    ASDC when X arm was unlocked = 55.45830 cnts

Those numbers correspond to a round trip loss of  78.780778 ppm, which sounds too small for me.

Quote from #5359

To see what was going on I will look at the trend data.
 

 

ELOG V3.1.3-