[Dsg-rich] Mirror 4 reflectivity results for visibly bad areas

[Tyler Lemon]

Hello Dr. Rossi, 

This morning, Mindy and I continued reflectivity measurements of Mirror 4. We measured two more spots (Spot 10 and Spot 11) that looked visibly bad and also repeated the measurement for Spot 3. Spot 3 was the area on the mirror where we unexpectedly measured a higher reflectivity on an area that looked smudged. These areas are noted by blue dots in the attached sketch of the mirror. 

The results for Spot 3 matched what was expected with an area that looked smudged. The reflectivity results were ~82%, lower than the ~90% measured previously for good spots. 

Spot 10 and Spot 11 also had reflectivity results lower than that of a good area. Spot 10 had a reflectivity of ~82% and Spot 11 had a reflectivity of ~77%. 

We will now move on to measuring the reflectivity of Mirror 3 in areas that looked bad. 

Best regards, 
Tyler 

From: "Patrizia Rossi" <rossi at jlab.org> 
To: "Tyler Lemon" <tlemon at jlab.org> 
Cc: "dsg-rich" <dsg-rich at jlab.org> 
Sent: Tuesday, August 22, 2017 5:11:10 PM 
Subject: Re: [Dsg-rich] Mirror 4 reflectivity results for visibly bad areas 

Excellent Tyler and company! 

These data are very important for my visit to the CMA 

patrizia 
--------------------------------------------------- 
# Patrizia Rossi 
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On 22/ago/2017, at 17:02, Tyler Lemon < tlemon at jlab.org > wrote: 

Hello Dr. Rossi, 

Attached are four reflectivity measurements for spots that visibly seem to be bad. The attached JPG shows the approximate location of the spots measured. 

Spot 7 corresponds to the area on the mirror where there is a small area without any reflective coating. All other spots were areas that looked smudged. 

The reflectivity measurements in these spots are lower, as expected, with spot 7 being the worst with a reflectivity of ~63%. 

We also took two calibration runs to ensure that photodiode A (the control photodiode) is stable and gives the similar results for every measurement. We are still in the process of looking at the calibration results and comparing photodiode A measurements, but just looking at the data, it appears that photodiode A was more stable for measurements of spot 7, spot 8, and spot 9 than the previous measurement set. 

Tomorrow we will measure a two more bad spots on mirror 4 and also repeat the previous measurement for Mirror 4 where we got an unexpected result. We will also measure bad areas of Mirror 3. 

Best regards, 
Tyler 
<Mirror4_2017-08-22_spot9.xlsx> <Mirror4_2017-08-22_spot8.xlsx> <Mirror4_2017-08-22_spot7.xlsx> <Mirror4_2017-08-22_spot6.xlsx> <Mirror 4 reflectivity test locations for visibly bad areas.JPG> _______________________________________________ 
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