 Fri Mar 19 15:26:19 2021, Aidan, Update, Computers, Activated MATLAB license on megatron
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| Activated MATLAB license on megatron |
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Fri Mar 19 15:31:56 2021, Aidan, Update, Computers, Activated MATLAB license on donatella
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| Activated MATLAB license on donatella |
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Fri Apr 15 22:54:20 2011, Aidan, Bryan, Update, Green Locking, Beat note amplitude on Vertex PD
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I was investigating the beat note amplitude on the vertex PD again yesterday. The incident power on the PD was 150uW in the PSL green beam and 700uW
in the X-ARM green beam. With perfect overlap and a transimpedance of 240, I expected to get a beat note signal of around 25mV or -19dBm. Instead, the
size was -57dBm. Bryan and I adjusted the alignment of the green PSL beam to try and improve the mode overlap but we couldn't do much better than about |
Wed Apr 13 23:32:07 2011, Aidan, Jamie, Configuration, LSC, AS PD and Camera installed 
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I spent some time tracking down the AS beam which had vanished from the AP table. Eventually, by dramatically mis-aligning SRM, PRM and ITMY, returning
BS to its Jan 1st PITCH and YAW values and tweaking the ITMX alignment [actual values to follow], I was able to get an AS beam out onto the AP table. I
verified that it was the prompt reflection off ITMX by watching it move as I changed the YAW of that optic and watching it stay stationary as I changed |
 Fri Apr 15 22:57:38 2011, Aidan, Jamie, Configuration, LSC, AS PD and Camera installed
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AS port ITMX YAW range where AS beam was visible = [-1.505, -1.225] - these extrema put the beam just outside of some aperture in the system ->
set ITMX YAW to -1.365
ITMX PITCH range = [-0.7707, -0.9707] -> set to ITMX PITCH to -0.8707 |
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Fri Apr 23 18:30:49 2010, Aidan, Jenne, Koji, Summary, Green Locking, Green means GO!
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Jenne, Koji and I assembled the Covesion Oven today, inserted a PPKTP crystal from Raicol, aligned the crystal to a 50mW focus and
got some green beam coming out.
Covesion Oven assembly |
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Thu Jan 27 17:12:02 2011, Aidan, Joe, Summary, Green Locking, Digital Frequency to Amplitude converter
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Joe and I built a very simple digital frequency to amplitude converter using the RCG. The input from an ADC channel goes through a filter bank (INPUT),
is rectified and then split in two. One path is delayed by one DAQ cycle (1/16384 s) and then the two paths are multiplied together. Then the output from
the mixer goes through a second filter bank (LP) where we can strip off twice the beat frequency. The DC output from the LP filter bank should be proportional |
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Fri Jan 28 10:27:46 2011, Aidan, Joe, Summary, Green Locking, Digital Frequency Discriminator - calibration
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One more thing ... we can calibrate the output of the LP filter to give a result in Hz with the following calibration:
LP_OUT = -1/(2*dt)*(LP_IN -1), where dt is 1/16384, the delay time of the delayed path.
Therefore LP_OUT = -8192*(LP_IN-1). |
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Thu Mar 10 16:00:53 2011, Aidan, Joe, Update, Green Locking, Intensity stabilization loop using beatnote DC.
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Aidan: Joe and I have added a channel that takes the DC output from the vertex beatnote PD and sends it, via RFM, to a DAC at the ETMX end. Immediately
before the output is a filter C1GCX_AMP_CTRL. The output of the DAC is connected to the CURRENT LASER DIODE modulation input on the back of the Innolight
driver. This will modulate the current by 0.1A/V input. |
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Tue Jun 22 09:45:21 2010, Aidan, Joe, Razib, Update, Phase Camera, Current phase camera setup. Seeing Acoustic beat
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We've set up a preliminary test bed for the phase camera. It simply uses a HeNe that is split into two beams. One is frequency shifted by an AOM
by -40 MHz - df, where df is some acoustic frequency. The second beam is transmitted through a 40MHz EOM to get sidebands. The two beams are recombined
and are, currently, incident on a photodetector, but this can be replaced by the phasecamera. |
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Thu Mar 24 19:48:13 2011, Aidan, Kiwamu, Update, Green Locking, Designs for permanent electronics for ALS
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Kiwamu and I looked at all the electronics that are currently in place for the green locking on the X-arm and have made a set of block diagrams of the
rack mounted units that we should build to replace the existing ... "works of art" that sprawl around out there at the moment.
Main items |
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Wed Mar 30 21:43:31 2011, Aidan, Kiwamu, Summary, Green Locking, Calculation of the green contrast on the RF PD
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Skip to final thought ...
Kiwamu and I have set about measuring the contrast of the signal on the RF PD. We can only do this when the end green laser is locked to the cavity.
This is because the green transmission through the cavity, when unlocked, is too low. Unfortunately, once we lock the green beam to the cavity, we can't |
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Wed Mar 30 21:46:10 2011, Aidan, Kiwamu, Update, Green Locking, States of the Green beat note
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The attached table shows the amplitude of the green beat note when the end laser was in various states. We can increase the beat note amplitude dramatically
by switching to a different states.
State 1 |
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Mon Apr 12 20:48:51 2010, Aidan, Mott, Summary, Green Locking, Temperature sweep of the Innolight: df/dT ~ 3.3GHz/K
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Quote:
The beams from the Innolight and Lightwave NPROs were both incident on a 1GHZ New Focus PD. Mott and I swept the |
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Tue Apr 13 12:39:51 2010, Aidan, Mott, Summary, Green Locking, Temperature sweep of the Innolight: df/dT ~ 3.3GHz/K
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Please put those numbers onto wiki somewhere at the green page or laser characterization page.
Quote:
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Tue Jun 10 12:49:46 2014, Akhil, Update, Computer Scripts / Programs, Interfacing UFC-6000 with Raspberry Pi completed
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Goal:
To interface the Mini Circuits RF Frequency Counter(FC) Model UFC-6000 with Raspberry Pi on Linux platform. Also to create a User friendly
interface, to control the FC with command lines. |
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Fri Jun 13 11:33:55 2014, Akhil, Update, Electronics, Characterization of UFC-6000 RF Frequency Counter
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Goal:
To characterize the Mini-Circuits RF FC (Model UFC-6000) and plot Bode Plots at varying Modulation frequencies.
Work Done: |
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Thu Jun 19 12:10:18 2014, Akhil, Update, Electronics, Gain plots to Characterize UFC-6000 RF Frequency Counter
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The goal is to characterize the Mini-Circuits RF FC (Model UFC-6000) by plotting Gain
Plots.
Work Done: |
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Wed Jun 25 01:18:24 2014, Akhil, Update, elog, Weekly Update
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Plans for the Week:
Phase and noise characterization of the UFC RF Frequency Counter.
Characterization of the temperature actuator.
Progress and Problems Faced: |
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Wed Jun 25 19:29:19 2014, Akhil, Update, Electronics, Analog-to-Digital Converter
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I have been trying to use an ADC with the Raspberry Pi to be able to measure the phase difference between FC input and output signals.I had a hard
time interfacing the ADC with the Pi (setup attached) even after trying to debug the issue for last two days. So I and Eriq Q performed a system
reboot on the Pi and tried all the possible ways for the Pi to detect the ADC but we were not able to. At the end we decided to order another IC(Microchip |
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Fri Jun 27 12:54:13 2014, Akhil, Update, Electronics, Gain plots of UFC-6000 for 0.1s Sampling Rate
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Finally, the 0.1s sampling rate of the frequency counter(FC) has been achieved. For this I had to :
Send in byte codes to set a particular range of the frequency counter.
I was digging in to find how exactly the circuit inside the frequency counter works and how the processor inside is able to read and write |
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Tue Jul 1 21:20:37 2014, Akhil, Update, Electronics, Gain plots of UFC-6000 for 0.1s Sampling Rate
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| The attached are the gain plots at carrier frequencies of 100 MHz, 500 MHz and 1 GHz measured using IFR 2023B (Marconi). |
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Fri Jul 4 09:17:13 2014, Akhil, Configuration, Electronics, Setup Used for Characterization of Frequency Counter
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Goal:
To complete the characterization of the Mini Circuits UFC-6000 RF Frequency Counter to be used for beat note
measurement as a part of frequency offset locking loop. The aim of this setup was to obtain the bode plots and PSD plots for the FC. |
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Mon Jul 7 13:56:13 2014, Akhil, Configuration, Electronics, Setup Used for Characterization of Frequency Counter
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When I was trying to plot PSD of the measurements, I still couldn't get better resolution. There still seems to be a problem with timing and synchronization
of the R Pi with the FC even after addition of the external trigger circuit. Now, I am looking to debug this issue. Attached are the plots showing missing
data points and data from the FC at uneven spacing(zoomed in plot). |
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Tue Jul 8 09:02:02 2014, Akhil, Update, Electronics, PSD Plots for different sampling times of the Frequency Counter 7x
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Although there were few timing issues with the FC and the Raspberry Pi at the lowest sampling time of the FC (0.1s) even after adding an external
trigger circuit, it turned out that most of these issues are not prevalent at higher sampling times(>0.5 s)(narrow peaks of PSD seen for higher sampling
times). Rana suggested me to look at the PSD plots at different sampling times of the FC so that we can decide which would be the optimal sampling time |
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Wed Jul 9 08:50:30 2014, Akhil, Update, General, Weekly Update
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Last Week's Work:
Worked on the setup to mitigate timing issues arising due to the non-synchronization of clocks of the |
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Wed Jul 9 12:01:43 2014, Akhil, Configuration, Electronics, Setup Plan for placing the Frequency Counter inside the lab
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Today, me and Manasa went inside the lab to figure out a place for the place for the FC. The whole setup will be placed in a chassis box . The chassis
in figure(setupforFC.pdf) will be placed in the highlighted(red) box in the figure(setup.png). All the cables will be routed to the computers from behind
the box and the RF cables from the beat box will be routed from the front end of the box. The two raspberry Pi boxes will be placed inside the box and |
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Thu Jul 10 17:53:19 2014, Akhil, Configuration, Computer Scripts / Programs, EPICS installed on Raspberry Pi
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I finished the installation of EPICS base on Raspberry Pi
(domenica: /opt/epics). I tested it by creating a test SoftIoc (controls@domenica~/freqCountIOC/simple.db) and was able to read from the channel
on Chiara. |
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Mon Jul 14 13:03:23 2014, Akhil, Summary, Electronics, Timing Issues of Mini Circuits UFC-6000: Solved
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Main Problem:
The frequency counter (FC) takes in an analog RF input(signal) and outputs the frequency of the signal(Ranging from 1 MHz- 6000 MHz) in the digital
domain (into a processor). The FC samples the data with a given sample rate( user defined) which ranges from 0.1 s to 1 s(faced problems in fixing this |
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Tue Jul 15 01:31:13 2014, Akhil, Summary, Electronics, Timing Issues of Mini Circuits UFC-6000: Solved
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The attached are the PSD plots with improved FC timing(with the same code as in http://nodus.ligo.caltech.edu:8080/40m/10151). More plots(Phase and PSD)
to follow.
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Wed Jul 16 07:51:52 2014, Akhil, Update, General, Weekly Update
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Work Done:
Solved all the timing issues pertaining to the R Pi and the FC.
Took all the measurements for complete characterization
of the frequency counter(Phase Plots to follow shortly).
Finished installation of the FC on the martian and created a channel for |
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Wed Jul 16 22:17:40 2014, Akhil, Summary, Electronics, Bode Plots and complete Characterization of Frequency Counter
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Goal:
To estimate the transfer function and the noise in the FC that is a part of the FOL-PID loop.
Measurements Taken: |
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Fri Jul 18 19:32:50 2014, Akhil, Summary, Electronics, Filters used inside the Frequency Counter
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Thanks Koji , for your hint for the brain teasing puzzle. I was looking into Filters that are usually used in devices like counters,
DSO and other scopes. I found that , to improve the quality of the measurement one of the best approach is averaging. I looked deeper into averaging |
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Mon Jul 21 12:16:27 2014, Akhil, Summary, Electronics, Filters used inside the Frequency Counter
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The expected bode plots for such a filter with L= 4 is attached and compared with the measured.
RXA: When comparing two things, please put them onto the same plot so that they can be compared. |
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Tue Jul 22 23:10:12 2014, Akhil, Update, General, Weekly Update
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Work Done:
Created a Channel Access Server on the Raspberry Pi to write data from the FC into EPICS Channel.
Completed characterization
and noise estimation of the FC counter with improved timing.
Started installation of FC inside the 40m.
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Wed Jul 23 11:15:54 2014, Akhil, Update, Electronics, Installation of FCs in the 40m
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As a part of installation of two(X-ARM and Y-ARM) frequency counters in the 40m, I have tested their performance when using them both on a single
Raspberry Pi. The timing plots are attached. There are almost no timing issues in this configuration and it can be said that there is no harm using both
of the FCs on the same platform. |
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Thu Jul 24 19:28:43 2014, Akhil, Update, General, Thermal Actuator Transfer Functions
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As a part of temperature actuator characterization, today Eric Q and I made some measurements for the open loop TF of both the X-arm and Y-arm
thermal actuators.
For this, we gave an input of random excitation for the temperature offset input( since we faced some serious issues when we gave |
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Sat Jul 26 10:12:19 2014, Akhil, Update, General, Data Acquisition from FC into EPICS Channels
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I succeeded in creating a new channel access server hosted on domenica ( R Pi) for continuous data acquisition from the FC into accessible
channels. For this I have written a ctypes interface between EPICS and the C interface code to write data into the channels. The channels which I created
are: |
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Sat Jul 26 13:10:14 2014, Akhil, Update, General, Thermal Actuator Transfer Functions
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Koji said that the method we used for X-arm thermal actuator TF measurement was not correct and suggested us to make measurements separately for high
and low frequencies( ensuring coherence at those frequencies is high).
(Edit by KA: The previous measurements for X/Y arm thermal actuators were done with each arm individually locked. This imposes the MC stability |
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Sat Jul 26 14:35:28 2014, Akhil, Update, General, Data Acquisition from FC into EPICS Channels
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Quote:
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Mon Jul 28 16:34:02 2014, Akhil, Update, General, Calibration of measured Thermal Actuator TFs
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To calibrate the measured TFs and characterize the thermal actuator for the FOL loop, we [ Me, Eric Q, Koji ] made the TF measurements of PZT response
by giving a disturbance to the position of each of X and Y arm ETM and ITM.
In order to make reasonable conclusions, the measurements were done at frequencies greater than 20 Hz (assuming the PZT response to be flat till |
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Mon Jul 28 17:53:00 2014, Akhil, Update, General, Work plan for the Upcoming weeks- FOL Project
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[Akhil, Harry]
Work Completed :
Frequency Counter: |
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Tue Jul 29 18:00:20 2014, Akhil, Update, LSC, Calibration of ETMX and ETMY actuators
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The ultimate goal of characterizing the temperature actuator turned to be fruitful in obtaining the calibration values for ETMX and ETMY (Calibration
of ITMs were done previously here but not for ETM). In this process, I measured the PZT response by displacing one of the test masses in the frequency range of 20 Hz and 900 Hz and |
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Wed Jul 30 11:15:44 2014, Akhil, Update, General, Weekly Update
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Plan for the week:
PID loop design and testing with the Green laser beat note by actuating the arm cavity length.
Beat note readout on MEDM
screens and Strip tool.
Calibration of the laser frequency response to PZT signal in MHz/V using a test DC input(Koji assigned me this task |
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Wed Jul 30 15:33:48 2014, Akhil, Summary, General, Calibrated Thermal Actuator TFs
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The goal of the measurements we made ( my previous 3 elogs) was to characterize the laser frequency thermal actuator that is a part of the FOL-
PID loop.
For this we made indirect TF measurements for the thermal actuator by looking at the PZT response by 1)arm cavity( ETM ,ITM) displacement and |
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Thu Jul 31 11:54:54 2014, Akhil, Summary, Electronics, PZT Calibration
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Koji asked me to get the calibration of the PZT counts to Volts for the the X and Y ends. Yesterday, I went inside the lab and took some measurements
from the digital readout of the PZT by giving in a DC offset(-5 to +5 volts) to PZT_Out and read out from these channels:
For X-end: C1:ALS-X-SLOW_SERVO1_IN1 |
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Thu Jul 31 14:23:28 2014, Akhil, Summary, Electronics, PZT Calibration
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The PZT seems to saturate at around +/- 3500 counts. So for the Y arm, I excluded the saturated points and fitted the data points again.
As for the calibration number, we expect the 3276.8 count/V for +/- 10 |
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Fri Aug 1 18:48:46 2014, Akhil, Summary, Electronics, PZT Calibration
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The PZT actuation on the laser frequency in MHz/V ( assuming the previous calibration here of
the PZT count/V) is : |
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Tue Aug 5 19:05:41 2014, Akhil, Update, General, Beat Note Testing on EPICS Channels
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Finally, the efforts put in the Frequency Counter paid off . I tested the working
of both the FC and EPICS channels that I created by displaying the beat note on MEDM screens. EricQ helped me locking the X arm ( Y arm free) thus acquiring |
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Tue Aug 5 19:20:05 2014, Akhil, Update, General, PID loop Design for beat note stabilization
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Today I and EricQ went inside the lab and set up the cables running from the a DAC channel into PZT input so that we can use the PID controller
to tune in the PZT offset to maintain the beat note within a detectable range (This is plan B as the main plan of actuating on the laser temperature can
be achieved only after the fiber setup with the PSL is ready). I obtained all the poles and zeroes of plant and started designing a PID loop to test it |