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Message ID: 195     Entry time: Mon May 9 12:06:10 2011
Author: tara, mingyuan 
Type: DailyProgress 
Category: Creak 
Subject: Q measurement for test blades 

We measured the weight needed for pulling the blades down, and measured Q, f0 of the blades. For Rom blade, the weight is 1.279 kg, f0 = 2.27 Hz, Q = 300. For Rem blade, the weight is 2.005kg, f0 = 2.35Hz, Q = 475.  The test blades are named Romulus(Rom) and Remus(Rem).

     Why do we do this:

    The maraging blades are designed to be flat when they are in used, so we need to know how much weight do we need to pull them down to their operating level. The weight will determine the size of the load mass we want in the drawing as well. We plan to mount mirror mount on the load mass, so we can align the mirror for the interferometer's end mirror.  Plus, resonance frequencies and Qs of the blades and seismic noise will be used to estimated the noise budget of the setup.

    The weight was applied to the blade until the blade horizontally leveled. Then the total weight was recorded.  After that, we used shadow sensing technique to determine their resonance frequencies and Q factors.

The results are summarized here:

Blade     load mass       f0               Q

Rom         1.279 kg       2.27 Hz     300

Rem         2.005           2.35 Hz      475

.Photo_74.jpg

fig1: determining the weight. The blade mounted on the table appears flat with the right weight.

 

rom.png

fig2: Q measurement from Rom

REM.png

fig3: Q measurement from Rem

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