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Add bubble/aluminium effect plots

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Thomas Dehaeze 2020-11-02 16:03:55 +01:00
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@ -3,7 +3,7 @@
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head> <head>
<!-- 2020-10-29 jeu. 11:20 --> <!-- 2020-11-02 lun. 16:03 -->
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<title>Attocube - Test Bench</title> <title>Attocube - Test Bench</title>
<meta name="generator" content="Org mode" /> <meta name="generator" content="Org mode" />
@ -35,30 +35,45 @@
<h2>Table of Contents</h2> <h2>Table of Contents</h2>
<div id="text-table-of-contents"> <div id="text-table-of-contents">
<ul> <ul>
<li><a href="#org8d030f4">1. Estimation of the Spectral Density of the Attocube Noise</a> <li><a href="#org301870a">1. Estimation of the Spectral Density of the Attocube Noise</a>
<ul> <ul>
<li><a href="#org50a760f">1.1. Long and Slow measurement</a></li> <li><a href="#orga74fad8">1.1. Long and Slow measurement</a></li>
<li><a href="#org70295ba">1.2. Short and Fast measurement</a></li> <li><a href="#org594bfe8">1.2. Short and Fast measurement</a></li>
<li><a href="#org17d3959">1.3. Obtained Amplitude Spectral Density of the measured displacement</a></li> <li><a href="#orgd9ca1ad">1.3. Obtained Amplitude Spectral Density of the measured displacement</a></li>
</ul>
</li>
<li><a href="#orgacf938d">2. Effect of the &ldquo;bubble sheet&rdquo; and <b>Aluminium tube</b></a>
<ul>
<li><a href="#org30a0a1b">2.1. Aluminium Tube and Bubble Sheet</a></li>
<li><a href="#orgfe4b4f1">2.2. Only Aluminium Tube</a></li>
<li><a href="#org5d943ee">2.3. Nothing</a></li>
<li><a href="#org6b21819">2.4. Comparison</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</div> </div>
</div> </div>
<div id="outline-container-org8d030f4" class="outline-2"> <div id="outline-container-org301870a" class="outline-2">
<h2 id="org8d030f4"><span class="section-number-2">1</span> Estimation of the Spectral Density of the Attocube Noise</h2> <h2 id="org301870a"><span class="section-number-2">1</span> Estimation of the Spectral Density of the Attocube Noise</h2>
<div class="outline-text-2" id="text-1"> <div class="outline-text-2" id="text-1">
<div id="orge0e29bf" class="figure"> <div id="org90d970d" class="figure">
<p><img src="figs/test-bench-shematic.png" alt="test-bench-shematic.png" /> <p><img src="figs/test-bench-shematic.png" alt="test-bench-shematic.png" />
</p> </p>
<p><span class="figure-number">Figure 1: </span>Test Bench Schematic</p> <p><span class="figure-number">Figure 1: </span>Test Bench Schematic</p>
</div> </div>
<div id="org2b65a6c" class="figure">
<p><img src="figs/IMG-7865.JPG" alt="IMG-7865.JPG" />
</p>
<p><span class="figure-number">Figure 2: </span>Picture of the test bench. The Attocube and mirror are covered by a &ldquo;bubble sheet&rdquo;</p>
</div>
</div> </div>
<div id="outline-container-org50a760f" class="outline-3"> <div id="outline-container-orga74fad8" class="outline-3">
<h3 id="org50a760f"><span class="section-number-3">1.1</span> Long and Slow measurement</h3> <h3 id="orga74fad8"><span class="section-number-3">1.1</span> Long and Slow measurement</h3>
<div class="outline-text-3" id="text-1-1"> <div class="outline-text-3" id="text-1-1">
<p> <p>
The first measurement was made during ~17 hours with a sampling time of \(T_s = 0.1\,s\). The first measurement was made during ~17 hours with a sampling time of \(T_s = 0.1\,s\).
@ -71,14 +86,14 @@ Ts = 0.1; <span class="org-comment">% [s]</span>
</div> </div>
<div id="org4beccfe" class="figure"> <div id="org64c5513" class="figure">
<p><img src="figs/long_meas_time_domain_full.png" alt="long_meas_time_domain_full.png" /> <p><img src="figs/long_meas_time_domain_full.png" alt="long_meas_time_domain_full.png" />
</p> </p>
<p><span class="figure-number">Figure 2: </span>Long measurement time domain data</p> <p><span class="figure-number">Figure 3: </span>Long measurement time domain data</p>
</div> </div>
<p> <p>
Let&rsquo;s fit the data with a step response to a first order low pass filter (Figure <a href="#org02547b0">3</a>). Let&rsquo;s fit the data with a step response to a first order low pass filter (Figure <a href="#orgc356556">4</a>).
</p> </p>
<div class="org-src-container"> <div class="org-src-container">
@ -102,17 +117,17 @@ The corresponding time constant is (in [h]):
<div id="org02547b0" class="figure"> <div id="orgc356556" class="figure">
<p><img src="figs/long_meas_time_domain_fit.png" alt="long_meas_time_domain_fit.png" /> <p><img src="figs/long_meas_time_domain_fit.png" alt="long_meas_time_domain_fit.png" />
</p> </p>
<p><span class="figure-number">Figure 3: </span>Fit of the measurement data with a step response of a first order low pass filter</p> <p><span class="figure-number">Figure 4: </span>Fit of the measurement data with a step response of a first order low pass filter</p>
</div> </div>
<p> <p>
We can see in Figure <a href="#org4beccfe">2</a> that there is a transient period where the measured displacement experiences some drifts. We can see in Figure <a href="#org64c5513">3</a> that there is a transient period where the measured displacement experiences some drifts.
This is probably due to thermal effects. This is probably due to thermal effects.
We only select the data between <code>t1</code> and <code>t2</code>. We only select the data between <code>t1</code> and <code>t2</code>.
The obtained displacement is shown in Figure <a href="#orgad8d3f9">4</a>. The obtained displacement is shown in Figure <a href="#orgb851634">5</a>.
</p> </p>
<div class="org-src-container"> <div class="org-src-container">
@ -126,10 +141,10 @@ t = t <span class="org-type">-</span> t(1);
</div> </div>
<div id="orgad8d3f9" class="figure"> <div id="orgb851634" class="figure">
<p><img src="figs/long_meas_time_domain_zoom.png" alt="long_meas_time_domain_zoom.png" /> <p><img src="figs/long_meas_time_domain_zoom.png" alt="long_meas_time_domain_zoom.png" />
</p> </p>
<p><span class="figure-number">Figure 4: </span>Kept data (removed slow drifts during the first hours)</p> <p><span class="figure-number">Figure 5: </span>Kept data (removed slow drifts during the first hours)</p>
</div> </div>
<p> <p>
@ -140,11 +155,29 @@ The Power Spectral Density of the measured displacement is computed
[p_1, f_1] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts); [p_1, f_1] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts);
</pre> </pre>
</div> </div>
<p>
As a low pass filter was used in the measurement process, we multiply the PSD by the square of the inverse of the filter&rsquo;s norm.
</p>
<div class="org-src-container">
<pre class="src src-matlab">G_lpf = 1<span class="org-type">/</span>(1 <span class="org-type">+</span> s<span class="org-type">/</span>2<span class="org-type">/</span><span class="org-constant">pi</span>);
p_1 = p_1<span class="org-type">./</span>abs(squeeze(freqresp(G_lpf, f_1, <span class="org-string">'Hz'</span>)))<span class="org-type">.^</span>2;
</pre>
</div>
<p>
Only frequencies below 2Hz are taken into account (high frequency noise will be measured afterwards).
</p>
<div class="org-src-container">
<pre class="src src-matlab">p_1 = p_1(f_1 <span class="org-type">&lt;</span> 2);
f_1 = f_1(f_1 <span class="org-type">&lt;</span> 2);
</pre>
</div>
</div> </div>
</div> </div>
<div id="outline-container-org70295ba" class="outline-3"> <div id="outline-container-org594bfe8" class="outline-3">
<h3 id="org70295ba"><span class="section-number-3">1.2</span> Short and Fast measurement</h3> <h3 id="org594bfe8"><span class="section-number-3">1.2</span> Short and Fast measurement</h3>
<div class="outline-text-3" id="text-1-2"> <div class="outline-text-3" id="text-1-2">
<p> <p>
An second measurement is done in order to estimate the high frequency noise of the interferometer. An second measurement is done in order to estimate the high frequency noise of the interferometer.
@ -152,45 +185,125 @@ The measurement is done with a sampling time of \(T_s = 0.1\,ms\) and a duration
</p> </p>
<div class="org-src-container"> <div class="org-src-container">
<pre class="src src-matlab">load(<span class="org-string">'./mat/test.mat'</span>, <span class="org-string">'x'</span>, <span class="org-string">'t'</span>) <pre class="src src-matlab">load(<span class="org-string">'./mat/short_test_plastic.mat'</span>)
Ts = 1e<span class="org-type">-</span>4; <span class="org-comment">% [s]</span> Ts = 1e<span class="org-type">-</span>4; <span class="org-comment">% [s]</span>
</pre> </pre>
</div> </div>
<div class="org-src-container">
<pre class="src src-matlab">x = detrend(x, 0);
</pre>
</div>
<p> <p>
The time domain measurement is shown in Figure <a href="#org8d7915d">5</a>. The time domain measurement is shown in Figure <a href="#orged82baf">6</a>.
</p> </p>
<div id="org8d7915d" class="figure"> <div id="orged82baf" class="figure">
<p><img src="figs/short_meas_time_domain.png" alt="short_meas_time_domain.png" /> <p><img src="figs/short_meas_time_domain.png" alt="short_meas_time_domain.png" />
</p> </p>
<p><span class="figure-number">Figure 5: </span>Time domain measurement with the high sampling rate</p> <p><span class="figure-number">Figure 6: </span>Time domain measurement with the high sampling rate</p>
</div> </div>
<p> <p>
The Power Spectral Density of the measured displacement is computed The Power Spectral Density of the measured displacement is computed
</p> </p>
<div class="org-src-container"> <div class="org-src-container">
<pre class="src src-matlab">win = hann(ceil(length(x)<span class="org-type">/</span>20)); <pre class="src src-matlab">win = hann(ceil(length(x)<span class="org-type">/</span>10));
[p_2, f_2] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts); [p_2, f_2] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts);
</pre> </pre>
</div> </div>
</div> </div>
</div> </div>
<div id="outline-container-org17d3959" class="outline-3"> <div id="outline-container-orgd9ca1ad" class="outline-3">
<h3 id="org17d3959"><span class="section-number-3">1.3</span> Obtained Amplitude Spectral Density of the measured displacement</h3> <h3 id="orgd9ca1ad"><span class="section-number-3">1.3</span> Obtained Amplitude Spectral Density of the measured displacement</h3>
<div class="outline-text-3" id="text-1-3"> <div class="outline-text-3" id="text-1-3">
<p> <p>
The computed ASD of the two measurements are combined in Figure <a href="#org68a3367">6</a>. The computed ASD of the two measurements are combined in Figure <a href="#org5032549">7</a>.
</p> </p>
<div id="org68a3367" class="figure"> <div id="org5032549" class="figure">
<p><img src="figs/psd_combined.png" alt="psd_combined.png" /> <p><img src="figs/psd_combined.png" alt="psd_combined.png" />
</p> </p>
<p><span class="figure-number">Figure 6: </span>Obtained Amplitude Spectral Density of the measured displacement</p> <p><span class="figure-number">Figure 7: </span>Obtained Amplitude Spectral Density of the measured displacement</p>
</div>
</div>
</div>
</div>
<div id="outline-container-orgacf938d" class="outline-2">
<h2 id="orgacf938d"><span class="section-number-2">2</span> Effect of the &ldquo;bubble sheet&rdquo; and <b>Aluminium tube</b></h2>
<div class="outline-text-2" id="text-2">
<div id="orgd503177" class="figure">
<p><img src="figs/IMG-7864.JPG" alt="IMG-7864.JPG" />
</p>
<p><span class="figure-number">Figure 8: </span>Aluminium tube used to protect the beam path from disturbances</p>
</div>
</div>
<div id="outline-container-org30a0a1b" class="outline-3">
<h3 id="org30a0a1b"><span class="section-number-3">2.1</span> Aluminium Tube and Bubble Sheet</h3>
<div class="outline-text-3" id="text-2-1">
<div class="org-src-container">
<pre class="src src-matlab">load(<span class="org-string">'./mat/long_test_plastic.mat'</span>);
Ts = 1e<span class="org-type">-</span>4; <span class="org-comment">% [s]</span>
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">x = detrend(x, 0);
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">win = hann(ceil(length(x)<span class="org-type">/</span>10));
[p_1, f_1] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts);
</pre>
</div>
</div>
</div>
<div id="outline-container-orgfe4b4f1" class="outline-3">
<h3 id="orgfe4b4f1"><span class="section-number-3">2.2</span> Only Aluminium Tube</h3>
<div class="outline-text-3" id="text-2-2">
<div class="org-src-container">
<pre class="src src-matlab">load(<span class="org-string">'./mat/long_test_alu_tube.mat'</span>);
Ts = 1e<span class="org-type">-</span>4; <span class="org-comment">% [s]</span>
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">x = detrend(x, 0);
</pre>
</div>
<p>
The time domain measurement is shown in Figure <a href="#orged82baf">6</a>.
</p>
<div class="org-src-container">
<pre class="src src-matlab">win = hann(ceil(length(x)<span class="org-type">/</span>10));
[p_2, f_2] = pwelch(x, win, [], [], 1<span class="org-type">/</span>Ts);
</pre>
</div>
</div>
</div>
<div id="outline-container-org5d943ee" class="outline-3">
<h3 id="org5d943ee"><span class="section-number-3">2.3</span> Nothing</h3>
</div>
<div id="outline-container-org6b21819" class="outline-3">
<h3 id="org6b21819"><span class="section-number-3">2.4</span> Comparison</h3>
<div class="outline-text-3" id="text-2-4">
<div id="org2d3dd04" class="figure">
<p><img src="figs/asd_noise_comp_bubble_aluminium.png" alt="asd_noise_comp_bubble_aluminium.png" />
</p>
<p><span class="figure-number">Figure 9: </span>Comparison of the noise ASD with and without bubble sheet</p>
</div> </div>
</div> </div>
</div> </div>
@ -198,7 +311,7 @@ The computed ASD of the two measurements are combined in Figure <a href="#org68a
</div> </div>
<div id="postamble" class="status"> <div id="postamble" class="status">
<p class="author">Author: Dehaeze Thomas</p> <p class="author">Author: Dehaeze Thomas</p>
<p class="date">Created: 2020-10-29 jeu. 11:20</p> <p class="date">Created: 2020-11-02 lun. 16:03</p>
</div> </div>
</body> </body>
</html> </html>

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View File

@ -44,6 +44,10 @@
#+caption: Test Bench Schematic #+caption: Test Bench Schematic
[[file:figs/test-bench-shematic.png]] [[file:figs/test-bench-shematic.png]]
#+name: fig:test-bench-picture
#+caption: Picture of the test bench. The Attocube and mirror are covered by a "bubble sheet"
[[file:figs/IMG-7865.JPG]]
** Matlab Init :noexport:ignore: ** Matlab Init :noexport:ignore:
#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name) #+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name)
<<matlab-dir>> <<matlab-dir>>
@ -150,22 +154,37 @@ The Power Spectral Density of the measured displacement is computed
[p_1, f_1] = pwelch(x, win, [], [], 1/Ts); [p_1, f_1] = pwelch(x, win, [], [], 1/Ts);
#+end_src #+end_src
As a low pass filter was used in the measurement process, we multiply the PSD by the square of the inverse of the filter's norm.
#+begin_src matlab
G_lpf = 1/(1 + s/2/pi);
p_1 = p_1./abs(squeeze(freqresp(G_lpf, f_1, 'Hz'))).^2;
#+end_src
Only frequencies below 2Hz are taken into account (high frequency noise will be measured afterwards).
#+begin_src matlab
p_1 = p_1(f_1 < 2);
f_1 = f_1(f_1 < 2);
#+end_src
** Short and Fast measurement ** Short and Fast measurement
An second measurement is done in order to estimate the high frequency noise of the interferometer. An second measurement is done in order to estimate the high frequency noise of the interferometer.
The measurement is done with a sampling time of $T_s = 0.1\,ms$ and a duration of ~100s. The measurement is done with a sampling time of $T_s = 0.1\,ms$ and a duration of ~100s.
#+begin_src matlab #+begin_src matlab
load('./mat/test.mat', 'x', 't') load('./mat/short_test_plastic.mat')
Ts = 1e-4; % [s] Ts = 1e-4; % [s]
#+end_src #+end_src
#+begin_src matlab
x = detrend(x, 0);
#+end_src
The time domain measurement is shown in Figure [[fig:short_meas_time_domain]]. The time domain measurement is shown in Figure [[fig:short_meas_time_domain]].
#+begin_src matlab :exports none #+begin_src matlab :exports none
figure; figure;
plot(t, 1e9*x) plot(t, 1e9*x)
xlabel('Time [s]'); ylabel('Displacement [nm]'); xlabel('Time [s]'); ylabel('Displacement [nm]');
xlim([0, 100]);
#+end_src #+end_src
#+begin_src matlab :tangle no :exports results :results file replace #+begin_src matlab :tangle no :exports results :results file replace
@ -179,7 +198,7 @@ The time domain measurement is shown in Figure [[fig:short_meas_time_domain]].
The Power Spectral Density of the measured displacement is computed The Power Spectral Density of the measured displacement is computed
#+begin_src matlab #+begin_src matlab
win = hann(ceil(length(x)/20)); win = hann(ceil(length(x)/10));
[p_2, f_2] = pwelch(x, win, [], [], 1/Ts); [p_2, f_2] = pwelch(x, win, [], [], 1/Ts);
#+end_src #+end_src
@ -205,3 +224,78 @@ The computed ASD of the two measurements are combined in Figure [[fig:psd_combin
#+caption: Obtained Amplitude Spectral Density of the measured displacement #+caption: Obtained Amplitude Spectral Density of the measured displacement
#+RESULTS: #+RESULTS:
[[file:figs/psd_combined.png]] [[file:figs/psd_combined.png]]
* Effect of the "bubble sheet" and *Aluminium tube*
** Introduction :ignore:
#+name: fig:picture-test-bench-aluminium-tube
#+caption: Aluminium tube used to protect the beam path from disturbances
[[file:figs/IMG-7864.JPG]]
** Aluminium Tube and Bubble Sheet
#+begin_src matlab
load('./mat/long_test_plastic.mat');
Ts = 1e-4; % [s]
#+end_src
#+begin_src matlab
x = detrend(x, 0);
#+end_src
#+begin_src matlab :exports none
figure;
plot(t, 1e9*x)
xlabel('Time [s]'); ylabel('Displacement [nm]');
#+end_src
#+begin_src matlab
win = hann(ceil(length(x)/10));
[p_1, f_1] = pwelch(x, win, [], [], 1/Ts);
#+end_src
** Only Aluminium Tube
#+begin_src matlab
load('./mat/long_test_alu_tube.mat');
Ts = 1e-4; % [s]
#+end_src
#+begin_src matlab
x = detrend(x, 0);
#+end_src
The time domain measurement is shown in Figure [[fig:short_meas_time_domain]].
#+begin_src matlab :exports none
figure;
plot(t, 1e9*x)
xlabel('Time [s]'); ylabel('Displacement [nm]');
#+end_src
#+begin_src matlab
win = hann(ceil(length(x)/10));
[p_2, f_2] = pwelch(x, win, [], [], 1/Ts);
#+end_src
** Nothing
** Comparison
#+begin_src matlab :exports none
figure;
hold on;
plot(f_1(8:end), sqrt(p_1(8:end)), '-', ...
'DisplayName', 'Alunimium + Bubble');
plot(f_2(8:end), sqrt(p_2(8:end)), '-', ...
'DisplayName', 'Aluminium');
hold off;
set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'log');
ylabel('ASD [$m/\sqrt{Hz}$]'); xlabel('Frequency [Hz]');
legend('location', 'northeast');
#+end_src
#+begin_src matlab :tangle no :exports results :results file replace
exportFig('figs/asd_noise_comp_bubble_aluminium.pdf', 'width', 'wide', 'height', 'normal');
#+end_src
#+name: fig:asd_noise_comp_bubble_aluminium
#+caption: Comparison of the noise ASD with and without bubble sheet
#+RESULTS:
[[file:figs/asd_noise_comp_bubble_aluminium.png]]