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New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Type Categorydown Subject
  59   Fri Jun 25 10:47:08 2010 AidanMiscaLIGO ModelingUploaded aLIGO axicon+ITM COMSOL model to the 40m SVN

I added a COMSOL model of the aLIGO ITM being heated by an axicon-formed annulus to the 40m SVN. The model assumes a fixed input beam size into an axicon pair and then varies the distance between the axicons. The output is imaged onto the ITM with varying magnitudes. The thermal lens is determined in the ITM and added  to the self-heating thermal lens (assuming 1W absorption, I think - need to check). The power in the annulus is varied until the sum of the two thermal lenses scatters the least amount of power out of the TEM00 mode of the IFO.

https://nodus.ligo.caltech.edu:30889/svn/trunk/comsol/TCS/aLIGO/

The results across the parameter space (axicon separation and post-axicon-magnification) are attached. These were then mapped from this space to the space of annulus thickness vs annulus diameter, (see elog here).

 

 

  60   Fri Jun 25 10:59:43 2010 AidanMiscaLIGO ModelingUploaded aLIGO axicon+ITM COMSOL model to the 40m SVN

Here are the results in the annulus thickness vs annulus diameter space ...

Quote:

I added a COMSOL model of the aLIGO ITM being heated by an axicon-formed annulus to the 40m SVN. The model assumes a fixed input beam size into an axicon pair and then varies the distance between the axicons. The output is imaged onto the ITM with varying magnitudes. The thermal lens is determined in the ITM and added  to the self-heating thermal lens (assuming 1W absorption, I think - need to check). The power in the annulus is varied until the sum of the two thermal lenses scatters the least amount of power out of the TEM00 mode of the IFO.

https://nodus.ligo.caltech.edu:30889/svn/trunk/comsol/TCS/aLIGO/

The results across the parameter space (axicon separation and post-axicon-magnification) are attached. These were then mapped from this space to the space of annulus thickness vs annulus diameter, also attached.

 

 

 

  157   Tue Jun 5 17:25:43 2012 Alex MauneyMiscaLIGO Modeling6/5/12 Daily Summary

- Had a meeting to talk about the basics of LIGO (esp. TCS) and discuss the project

- Created COMSOL model for the test mass with incident Gaussian beam.

- Added a ring heater to the previous file

- Set up SVN for the COMSOL repository

  158   Wed Jun 6 16:54:09 2012 Alex MauneyMiscaLIGO Modeling6/6/12 Daily Summary

- Got access to and started working with SIS on Rigel1

- Fixed SVN issues

- Refined COMSOL model parameters and worked on a better way to implement the heating ring to get the astigmatic heating pattern.

  160   Thu Jun 7 16:50:16 2012 Alex MauneyMiscaLIGO Modeling6/7/12 Daily Summary

- Created a COMSOL model with thermal deformations

- Added non-symmetrical heating to cause astigmatism

- Worked on a method to compute the optical path length changes in COMSOL

  162   Fri Jun 8 16:36:47 2012 Alex MauneyMiscaLIGO Modeling6/8/12 Daily Summary

- Tried to fix COMSOL error using the (ts) module, ended up emailing support as the issue is new in 4.3

- Managed to get a symmetric geometric distortion by fixing the x and y movements of the mirror to be zero (need to look for a better way to do this as this may be unphysical)

- Worked on getting the COMSOL data into SIS, need to look through the SIS specs to find out how we should be doing this (current method isn't working well)

 

  164   Mon Jun 11 17:11:01 2012 Alex MauneyMiscaLIGO Modeling6/11/12 Daily Summary

- Fixed the (ts) model, got strange results that indicate that the antisymmetric heating mode is much more prominent than previously thought

- Managed to get COMSOL data through matlab and into SIS

 

  166   Wed Jun 13 16:36:14 2012 Alex MauneyMiscaLIGO Modeling6/12 and 6/13 Daily Summary

- Realized that the strange deformations that we were seeing only occur on the face nearest the ring heater, and not on the face we are worried about (the HR face)

- Read papers by Morrison et al. and Kogelnik to get a better understanding of the mathematics and operations of the optical cavity modeled in SIS

- Read some of the SIS manual to better understand the program and the physics that it was using (COMSOL licenses were full)

  168   Thu Jun 14 16:51:03 2012 Alex MauneyMiscaLIGO Modeling6/14/12 Daily Summary

- Plugged the output of the model with uniform heating into SIS using both modification of the radius of curvature, and direct importation of deflection data

- Generated a graph for asymmetric heating and did the same

- Aligned axes in model to better match with the axes in MATLAB and SIS so that the extrema in deflections lie along x and y (not yet implemented in the data below)

  169   Mon Jun 18 16:30:36 2012 Alex MauneyMiscaLIGO Modeling6/18/12 Daily Summary

- Verified that the SIS output does match satisfy the equations for Gaussian beam propagation

- Investigated how changing the amount of data points going into SIS changed the output, as well as how changes in the astigmatic heating effect the output

     + The results are very dependent on number of data points (similar order changes to changing the heating)

     + Holding the number of data points the same, more assymetric heating tends to lead to more power in the H(2,0) mode, and less in the H(0,2)

 

  171   Tue Jun 19 16:24:52 2012 Alex MauneyMiscaLIGO Modeling6/19/12 Daily Summary

- Did more modeling for different levels of heating and different mesh densities for the SIS input.

- Lots of orientation stuff

- Started on progress report.

  172   Wed Jun 20 16:44:58 2012 Alex MauneyMiscaLIGO Modeling6/20/12 Daily Summary

- Attended a lot of meetings (Safety, LIGO Orientation)

- Finished draft of week 3 report (images attached)

 

  174   Thu Jun 21 16:54:45 2012 Alex MauneyMiscaLIGO Modeling6/21/12 Daily Summary

- Paper edits and more data generation for the paper (lower resolution grid data)

- Attended a talk on LIGO

 

  177   Wed Jun 27 16:43:56 2012 Alex MauneyMiscaLIGO Modeling6/27/12 Daily Summary

Plan for building the model

- Find the fields that would be incident on the beam splitter from each arm (This is done already)

- Propagate these through until they get to the OMC using the TELESCOPE function in SIS

- Combine the fields incident on the OMC in MATLAB and minimize the power to get the input field for the OMC (Most of this is done, just waiting to figure out what kind of format we need to use it as an SIS input)

- Model the OMC as an FP cavity in SIS

    + Need to think about how to align the cavity in a sensible way in SIS (need to find out more about how they actually do it)

- Pick off the fields from both ends of the OMC-FP cavity for analysis

- Add thermal effects to one of the arms and see how that changes the fields, specifically how the signal to noise ratio changes

  178   Thu Jun 28 16:27:37 2012 Alex MauneyMiscaLIGO Modeling6/28/12 Daily Summary

- Finished the MatLab code that both combines two fields and simulates the adjustment of the beamsplitter to minimize the power out (with a small offset).

- Added the signal recycling telescope to the SIS code that generates the fields

To Do: Make the OMC cavity in SIS

 

  180   Mon Jul 9 16:54:17 2012 Alex MauneyMiscaLIGO Modeling7/9/12 Summary

Made a COMSOL model that can include CO2 laser heating, self heating, and ring heating

Figured out how to run SIS out of a script and set up commands to run the two SIS stages of the model

  40   Thu May 20 10:44:13 2010 AidanElectronicsSLEDQPhotonics 980nm source power

dV = 0.385V

Responsivity= 0.65A/W

Transimpedance = 1.5E4 V/A

therefore power= 0.385V / (1.5E4 * 0.65 V/W) = 40uW

 

 

  41   Thu May 20 17:08:36 2010 AidanElectronicsSLEDSLED module - and driver - LIGO D1000892 - and Hartmann sensor

Verified that the test-point for the current limit pot on the driver (Wavelength Electronics - LDTC 0520) was at 0.5V. Driver is set to INTERNAL set point at the moment. This is down about 10% below the current limited point.

Voltage across TP7 and TP9 = 0.970V = LD Current Mon

Voltage across TP2 and TP3 = 0.017V = LD P Mon

 

--- Hartmann sensor ---

-set the sampling rate on the CCD to 16HZ. With the current alignment and intensity this gives as maximum intensity of around 3850 out of 4095. Thus the pixels are not saturated.

- centroid_image located some of the spots - see attached image of spots where those located by the algorithm and circled. I need to play with the threshold level and spot_radius to get this to work properly.

 

 

  43   Wed May 26 06:47:02 2010 AidanLaserSLEDSwitched off SLED - 6:40AM
  75   Sun Jul 25 16:24:56 2010 AidanComputingSLEDSuperlum SLED test integrated with DAQ - new channel names

 I added some new channels to the Athena DAQ that record the diagnostic channels from the Superlum SLED.

  • C4:TCS-ATHENA_I_SET_VOLTS:  - the set current signal in Volts (1V = 1A)
  • C4:TCS-ATHENA_I_ACTUAL_VOLTS:   - a signal proportional to the actual current flowing to the SLED (1V = 1A)
  • C4:TCS-ATHENA_I_LIM_VOLTS: - the current limit signal in volts (1V = 1A)
  • C4:TCS-ATHENA_TEMP_SENS_V:   - the signal from the on-board temperature sensor [thermistor] (1V = 10kOhm ?)
  • C4:TCS-ATHENA_PD_VOLTAGE: - the signal from the on-board photodetector (1V = 1A?)

The ioc that handles the EPICS channels is on tcs_daq(10.0.1.34) in /target/TCS_westbridge.db

The channels are added to the frame builder in /cvs/cds/caltech/chans/daq/C4TCS.ini

Currently, the driver for the SLED is ON but the current to the SLED is off. This is to check that the zero value of the PD_VOLTAGE signal doesn't wander.

Also, the input noise of the Athena is around +/- 10 counts (where 2^15 counts = 10V) which is a pretty poor 3mV.

  76   Mon Jul 26 09:42:30 2010 AidanComputingSLEDLong term test on SLED started - Day 0

 I set up the SLED to test its long term performance. The test began, after a couple of false starts, around 9:15AM this morning.

The output of the fiber-optic patch cord attached to the SLED is illuminating a photo-detector. The zero-level on the PD was 72.7mV (with the lights on). Once the PD was turned on the output was ~5.50 +/- 0.01V. This is with roughly 900uW exiting the SLED.

The instructions from Superlum suggest limiting the amount of power coupled back into the fiber to less than 3%. With the current setup, the fiber is approximately 2" from the photodetector. What is the power coupled back into the fiber?

Assume a worst case of 100% of the light reflected from the PD, the wavelength is 830nm and a waist size of about 6um radius at the output of the fiber. The beam size at 4" (from the fiber output to the PD and back again) or ~100mm from the fiber is about 4.4mm radius. Therefore about (6um/4.4mm)^2 or ~2ppm will be coupled back into the fiber. This is sufficiently small.

The attached plots from dataviewer show measurements from the SLED (on-board photodetector, on-board temperature sensor, current setpoint, current limit, current to diode) over the last 15 hours.

  79   Tue Jul 27 08:31:10 2010 AidanElectronicsSLEDLong term SLED test - Day 1

 The measurement from the on-board PD of the Superlum SLED seems to be falling. This effect started around 5PM last night which is right about the time we moved the position of the PD that the SLED is illuminating on the optical table (via optical fiber).

Curiously, the current set point and delivered current to the SLED are dropping as well. 

  80   Wed Jul 28 18:32:12 2010 AidanElectronicsSLEDSLED long term test - Day 2

Here's the data from the last 2 1/2 days of running the SLED. The decrease in photo-current measured by the on-board photo-detector is consistent with the decrease in the current set-point and the delivered current, but it is not clear why these should be changing.

Strictly speaking I should add some analysis that shows that delta_PD_voltage_measured = delta_I_set_measured * [delta_PD_voltage/delta_I_set (I_set)]_calculated ...

  81   Thu Jul 29 10:09:19 2010 AidanElectronicsSLEDSLED long term test - Day 2

I've attached the Acceptance Test Report data from SUPERLUM for this SLED. I've also determined the expected percentage decrease in power/photo-current per mA drop in forward current.

The measured decrease in forward current over the last 2 1/2 days is around 1.4mA from around 111mA. The expected drop in power is thus (4.5% per mA)*(1.4mA) = 6.3%.

The drop in photo-current is around 37.5mA to 35mA = 2.5mA. The percentage drop is around 100*(2.5mA)/(36.3mA) = 6.9%. 

Therefore, the drop in measured power is consistent with what we would expect given the decrease in forward current (which is consistent with the drop in the set point). Why the set-point is dropping is still a mystery.

Quote:

Here's the data from the last 2 1/2 days of running the SLED. The decrease in photo-current measured by the on-board photo-detector is consistent with the decrease in the current set-point and the delivered current, but it is not clear why these should be changing.

Strictly speaking I should add some analysis that shows that delta_PD_voltage_measured = delta_I_set_measured * [delta_PD_voltage/delta_I_set (I_set)]_calculated ...

 

  87   Sat Jul 31 11:54:20 2010 AidanComputingSLEDSLED Test Day 5 - Re-tuned current set-point control voltage

Main Points

  • Re-set SLED current set-point control voltage to 0.111V
  • SLED current set-point voltage drops by about 5mV when the SLED is dis-engaged
  • Resetting was around 11:45AM PDT 31st-Jul-2010

I turned off the SLED for 10s and reset the current set-point voltage (read using a mutlimeter and probing a couple of pins at the back of the driver board). The initial voltage when the test started on Monday was 0.111V when the SLED was engaged. This drooped to 0.109V over the week and there was a corresponding (but possible not resulting) drop in on-board photo-diode voltage. When the SLED was disengaged the set-point current control voltage dropped to 0.104V. I turned the LP pot on the front of the SLED driver board until the multimeter read 0.106V and re-engaged the SLED. The curernt set-point voltage then read 0.111V, occasionally popping up to 0.112V for a moment or two.

The DC Power Supply to the SLED reads 8.9V with 0.26A current being drawn.

  89   Mon Aug 9 10:58:37 2010 AidanLaserSLEDSLED 15-day trend

 Here's a plot of the 15-day output of the SLED.

Currently there is an 980nm FC/APC fiber-optic patch-cord attached to the SLED. It occurred to me this morning that even though the patch cord is angle-cleaved, there may be some back-reflection than desired because the SLED output is 830nm (or thereabouts) while the patch cord is rated for 980nm.

 I'm going to turn off the SLED until I get an 830nm patch-cord and try it then. 

Correction: I removed the fiber-optic connector and put the plastic cap back on the SLED output. The mode over-lap (in terms of area) from the reflection off the cap with the output from the fiber is about 1 part in 1000. So even with 100% reflection, there is less than the 0.3% danger level coupled back into the fiber. The SLED is on again.

  7   Thu Feb 4 14:05:59 2010 AidanElectronicsRing HeaterRing heater transfer function measurement 240mHz-5Hz

I've been trying to measure the ring heater transfer function (current to emitted power) by sweeping the supply voltage and measuring the emitted power with a photodector positioned right next to the ring heater.

Last night the voltage was sweeping with a 1000mV setting on the SR785 which was fed into the Voltage Control of the Kepco Bipolar Operational Power Supply/Amplifier which was biased around 10V.

The results are very, very strange. The magnitude of the transfer function decreases at lower frequency. I'll post the data just as soon as I can (ASCII dumps 13 and 14 on the disk from the SR785).

The circuit looks like this:

 

SR785 drive ----> Amplifier ----> Ring Heater : Photodetector ---> SR560 (5000x gain) ----> SR785 input

 

 

  8   Thu Feb 4 15:26:37 2010 AidanElectronicsRing HeaterRing heater transfer function measurement 240mHz-5Hz

Quote:

I've been trying to measure the ring heater transfer function (current to emitted power) by sweeping the supply voltage and measuring the emitted power with a photodector positioned right next to the ring heater.

Last night the voltage was sweeping with a 1000mV setting on the SR785 which was fed into the Voltage Control of the Kepco Bipolar Operational Power Supply/Amplifier which was biased around 10V.

The results are very, very strange. The magnitude of the transfer function decreases at lower frequency. I'll post the data just as soon as I can (ASCII dumps 13 and 14 on the disk from the SR785).

The circuit looks like this:

 

SR785 drive ----> Amplifier ----> Ring Heater : Photodetector ---> SR560 (5000x gain) ----> SR785 input

 

 

 This is wrong. It turns out the SR785 was wired up incorrectly.

  9   Thu Feb 4 19:45:56 2010 AidanMiscRing HeaterRing heater transfer function - increasing collection area

I mounted the thinner Aluminium Watlow heater inside a 14" long, 1" inner diameter cylinder. The inner surface was lined with Aluminium foil to provide a very low emissivity surface and scatter a lot of radiation out of the end. ZEMAX simulations show this could increase the flux on a PD by 60-100x. 

There was 40V across the heater and around 0.21A being drawn. The #9005 HgCdTe photo-detector was placed at one end of the cylinder to measure the far-IR. (Bear in mind this is a 1mmx1mm detector in an open aperture of approximately 490 mm^2), The measured voltage difference between OFF and the steady-state ON solution, after a 5000x gain stage, was around 270mV. This corresponds to 0.054mV at the photo-diode. Using the responsivity of the PD ~= 0.05V/W then this corresponds to about 10mW incident on the PD.

 

  13   Thu Feb 11 18:04:08 2010 AidanLaserRing HeaterRing heater time constant

I've been looking to see what the time constant of the ring heater is. The attached plot shows the voltage measured by the photodiode in response to the heater turning on and off with a period of 30 minutes.

The time constant looks to be on the order of 600s.

  14   Thu Feb 11 21:46:23 2010 AidanElectronicsRing HeaterRing heater time constant measurement - start time

After leaving the ring heater off for several hours I turned on a 40V, 0.2A supply at a gps time of 949 988 700

The channel recording the PD response is C2:ATF-TCS_PD_HGCDTE_OUT.

However, there is a delay between the time at which something is supposed to be recorded and the time at which it is recorded. I looked at the GPS clock and it read that time when I started the heater voltage. If you play the channel back in dataviewer you see the temperature start to increase around 80s BEFORE the heater current was switched on. This needs to be calibrated away!!!

  15   Fri Feb 12 11:39:28 2010 AidanElectronicsRing HeaterRing heater transfer function

I applied a step function to the silver WATLOW heater and measured the response with the photodiode. The power spectrum of the derivative of the PD response is attached. The voltage isn't calibrated, but that's okay because right now we're just interested in the shape of the transfer function. It looks like a single pole around 850uHz. The noise floor is too great above 4 or 5 mHz to say anything about the transfer function.

 

 

  16   Fri Feb 12 21:00:06 2010 AidanElectronicsRing HeaterRing heater step function response - time series

Hideously slow internet at airport is making me write a brief entry. This is the times series of the hesilver watlow heater radiative response to a step function.

Laso United airlines are a bit cheap ....

  112   Thu Feb 24 14:20:55 2011 AidanMiscRing HeateraLIGO H2 Ring Heater Pics

 Here are some pictures of the ring heater segments destined for the H2 Y-arm this year.

 These still need to be put onto ResourceSpace.

  239   Fri Aug 9 20:33:11 2019 JonElectronicsRing HeaterPower-regulated heater ready to use

Despite some considerable time spent, I was not able to get the Omega SCR controllers working. The first unit definitely arrived damaged. None of its LED indicator lights ever functioned, despite those on the second controller working fine under the same setup. I tried swapping in the second controller, but it has no voltage output and a red LED is illuminated which, according to the manual, means "malfunction on trigger board" or "open SCR."  Either way, the remedy is to "consult factory."

Since we have get moving with data collection, I installed a simple variable transformer (borrowed from the 40m) which steps up/down the AC voltage from 0-120 V with the turn of a knob. I soldered the leads of one of the heaters to a standard power cable which plugs directly into the transformer. I have tested it and confirmed it to work.

  10   Fri Feb 5 12:42:19 2010 SteveElectronicsPre-amplifierChanges to board

Test entry

  11   Mon Feb 8 10:45:50 2010 Steve O'ConnorElectronicsPre-amplifierreplace Pot with fixed Resistor

 

            Preamp for Bulls eye detector                
                             
  It was felt that the Pot used at the input stage to remove offset added Noise            
  To test this the Pot was replaced with a fixed resistor and the offset removed at the second stage        
  Noise was measured after the first stage and at the monitor point first with the pot and then with the pot replaced with a Resistor  
                             
              First stage gain =1+500/10 test point 1 gain = 51      
              second stage gain=10K/1K test point 2 gain = 510    
  1K Pot (R19) is present                      
                             
  Chan #1                          
    dbVrms/Hz       nV/Hz       Referred Input Noise  nV/Hz      
                    gain = 51        
    200Hz 100Hz 50Hz   200Hz 100Hz 50Hz   200Hz 100Hz 50Hz    
  Test Point #1 -141.1 -140.0 -136.8   88.1 100.0 144.5   1.7 2.0 2.8    
                    gain = 510        
  Test Point #2 -119.4 -120.4 -118.4   1071.5 955.0 1202.3   2.1 1.9 2.4    
                             
                             
                             
  Pot replaced with Resistor (R4)                    
                             
  Chan #1                          
    dbVrms/Hz       nV/Hz       RIN        
                    gain = 50        
    200Hz 100Hz 50Hz   200Hz 100Hz 50Hz   200Hz 100Hz 50Hz    
  Test Point #1 -142.7 -142.7 -141.9   73.7 73.3 80.8   1.4 1.4 1.6    
                    gain = 500        
  Test Point #2 -122.0 -121.1 -120.7   794.3 881.0 922.6   1.6 1.7 1.8    
                             
                             
  When the Pot was replaced with R4, the offset was removed with the Pot at the second gain stage          
  R4 was not a thin film metal resistor                    
  12   Mon Feb 8 17:44:38 2010 AidanElectronicsPre-amplifierreplace Pot with fixed Resistor

Quote:

 

            Preamp for Bulls eye detector                
                             
  It was felt that the Pot used at the input stage to remove offset added Noise            
  To test this the Pot was replaced with a fixed resistor and the offset removed at the second stage        
  Noise was measured after the first stage and at the monitor point first with the pot and then with the pot replaced with a Resistor  
                             
              First stage gain =1+500/10 test point 1 gain = 51      
              second stage gain=10K/1K test point 2 gain = 510    
  1K Pot (R19) is present                      
                             
  Chan #1                          
    dbVrms/Hz       nV/Hz       Referred Input Noise  nV/Hz      
                    gain = 51        
    200Hz 100Hz 50Hz   200Hz 100Hz 50Hz   200Hz 100Hz 50Hz    
  Test Point #1 -141.1 -140.0 -136.8   88.1 100.0 144.5   1.7 2.0 2.8    
                    gain = 510        
  Test Point #2 -119.4 -120.4 -118.4   1071.5 955.0 1202.3   2.1 1.9 2.4    
                             
                             
                             
  Pot replaced with Resistor (R4)                    
                             
  Chan #1                          
    dbVrms/Hz       nV/Hz       RIN        
                    gain = 50        
    200Hz 100Hz 50Hz   200Hz 100Hz 50Hz   200Hz 100Hz 50Hz    
  Test Point #1 -142.7 -142.7 -141.9   73.7 73.3 80.8   1.4 1.4 1.6    
                    gain = 500        
  Test Point #2 -122.0 -121.1 -120.7   794.3 881.0 922.6   1.6 1.7 1.8    
                             
                             
  When the Pot was replaced with R4, the offset was removed with the Pot at the second gain stage          
  R4 was not a thin film metal resistor                    

 

Just a note: this board was for the QPD not the Bull's eye detector.

 

  104   Tue Jan 25 16:38:16 2011 AidanElectronicsPre-amplifierL1 TCSY ISS Board transfer function

 I measured the AC and DC channel transfer functions of the eLIGO L1 TCSY ISS board for PD1 and PD2. The gain is quite high on the AC channels so I added +40dB of attenuation to the source from the SR785. As Frank pointed out, even though this isn't exactly +40dB at low frequencies, it still attenuates and that attenuation is common to both the input to the Channel 1 of the SR785 and the input to the ISS board.

The results are shown in the attached plot. I didn't bother including the phase, I'm just interested in the magnitude for calibration purposes.

 The original data files from the SR785 are attached below: 

Channel Name Filename
L1 TCSY PD1 - AC SRS003.78D
L1 TCSY PD2 - AC SRS004.78D
L1 TCSY PD1 - DC SRS005.78D
L1 TCSY PD2 - DC SRS006.78D

 

  153   Thu Sep 1 15:51:38 2011 AidanLaserOrderingAccess Lasy50 50W laser arrived.

 The 50W Access Laser is now in the lab. We need to wire up the interlock to the laser, plumb the chiller lines to the power supply and to the laser head and also wire up all the electrical and electronics cables. Additionally, we will need to plumb the flow meter and attach a circuit to it that triggers the interlock if the flow falls too low.

 

  223   Fri Oct 26 09:49:47 2018 AidanMiscOpticsStarting 80C cure of epoxy

I've started an 80C cure of two materials bonded by EPOTEK 353ND. The objective is to see (after curing) how much the apparent glass transition temperature is increased over a room-temperature cure.

  234   Wed Jul 24 16:25:13 2019 Edita BytyqiLab InfrastructureOpticsUpdated 2-lens setup

The previous 2-lens setup focused the beam to a tight spot, however due to the divergence angle of the laser beam, a significant amount of power was not being captured by the fiirst lens at a distance of 40 cm from the source. The divergence angle seems to be bigger than 0.06 by a factor of 2, so a f = 20 cm lens was used to collimate the beam and a f = 30 cm lens was used to focus it. A mirror was used to reflect the beam, so we obtain steering control. Additionally, the focusing lens was placed on a small 1-axis stage in order to control the distance of the lens from the CCD, providing control over the focused beam size.

Note: The 30 cm lens was cleaned with methanol, however it still has some residue on the surface. The beam imaged to the Harrtmann Sensor looks good, however the lens will be cleaned by using a different solvent or replaced by a different 30 cm lens. The 3 lenses at the edge of the box will stay inside in order to prevent contamination, however they will not be used in the design.

  236   Mon Jul 29 18:53:16 2019 Edita BytyqiLab InfrastructureOpticsMounted Reflector and Heater

Since we set up the 2-lens system focusing the laser beam to the CCD, the next step was to mount the spherical reflector (31 mm wide) and the heater (~3 mm diameter). I used a small 3-axis stage to mount the heater, providing 3 degrees of freedom that would allow to manipulate the height of the heater, its position with respect to the reflector (left-right and in-out). The reflector was mounted in such a way that we can control its rotation angle, height and horizontal displacement. The current design is not quite sophisticated as it is just a first test, however I will look into different tools in the lab to see if I can use less mounts to get the same degrees of freedom.

The new heaters are supposed to be heated using AC. We used a DC power supply and ran ~30V through the wire, however only about ~50 mA of current was running through it. Jon will look into the specs of the new heaters to see if the power supply was the problem.

  237   Thu Aug 1 15:20:39 2019 Edita BytyqiLab InfrastructureOpticsReflector Mount and DC Supply

Yesterday, we were able to take some data using the 120 V DC power supply. The reflectors cut at the focal point and radius were both tested; the semi-circle cut proved to give a better focus, likely because roughly half the heat is lost using the focal-point reflectors. For upcoming tests, the semicircle reflectors will be used. We varied the surface shine by using the dull and reflective side of Al foil, as well as using the machined Al itself. The best result was given by using the more reflective side of Al foil.

Figure 1 shows the steady-state surface deformation profile detected by the HWS. The heaters don't have a uniform distribution along the wire, so more heat is radiated in the center of it, thus more of it is being focused to the center of the test optic. The data needs to be analyzed to determine the radius of the focus. Our rough estimate is about ~1.5 - 2 cm. We cannot collect any more data until we get a new power supply (AC 120 V).

Today, I came up with a new design for mounting the reflectors. I used a big 3-axis stage and a small 4-axis stage. This provides 5 degrees of freedom: 3 translational and 2 rotational, which is what we need for fine-tuning the focus and directing it at different angles incident to the test optic. The only problem with this design is that the 3-axis stage is too tall for the box, so the lid won't close.There is a smaller one available, but I have to figure out a way to increase its height, since the screw size is different from the ones on the pedestals available.

Additionally, Chub used metal-to-metal epoxy to glue a screw to the back of a reflector. I will wait until tomorrow to test it, because it is a slow acting epoxy. If it works, I have the necessary tools to do the same with the other reflectors. With the current deisgn the reflector wil be screwed in to where the round screw is in the stage. If it heats up a lot and affects the material of the stages, a small optical post (top of stage) will be used to make up for the absorbed heat.

 

  141   Sun Apr 24 18:31:18 2011 AidanComputingNetwork architectureAdded hosts and network drives on TCS machines

Under edit ...

I added the names of the network machines to the /etc/hosts file on princess_sparkle, tcs_daq and tcs_ws.

I also added the /cvs drive on fb1 to the /etc/fstab file on princess_sparkle so that can be accessed from those machines.

  142   Mon Apr 25 16:28:27 2011 Aidan, JoeComputingNetwork architectureFixed problem network drive fb1:/cvs on Ubuntu & CentOS machines

With Joe's help we fixed the failure of princess_sparkle to mount the fb1:/cvs directory when relying on /etc/fstab.

First we changed the mounting options in fstab to the following:

fb1:/cvs        /cvs            nfs     rw,bg,soft        1 1

When we got the following error trying it directly from the command line,

controls@princess_sparkle:~$ sudo mount /cvs
[sudo] password for controls:
mount: wrong fs type, bad option, bad superblock on fb1:/cvs,
       missing codepage or helper program, or other error
       (for several filesystems (e.g. nfs, cifs) you might
       need a /sbin/mount.<type> helper program)
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

some quick Google searches suggested installing nfs-common, so we tried sudo apt-get install nfs-common and that seemed to do the trick.

CentOS

For the CentOS machines, the following was done:

sudo mkdir /cvs

and then the same mounting configuration was added to /etc/fstab
 

Additionally, all three machines now have a /users symbolic link to /cvs/users

  182   Thu Dec 15 14:02:01 2016 AidanComputingNetwork architectureCorrect network settings for Ubuntu 14 in /etc/network/interfaces

These settings work to get a computer onto the TCS/ATF network.

  183   Fri Dec 16 10:41:33 2016 AidanComputingNetwork architectureCorrect network settings for Ubuntu 14 in /etc/network/interfaces

Spelt out in a searchable fashion:

auto <portname>

iface <portname> inet static

   address 10.0.1.x

   netmask 255.255.255.0

   network 10.0.1.0

   broadcast 10.0.1.255

   gateway 10.0.1.1

   dns-nameservers 10.0.1.1 131.215.139.100 8.8.8.8

 

 

Quote:

These settings work to get a computer onto the TCS/ATF network.

 

  203   Tue Nov 14 19:08:00 2017 Jon RichardsonComputingNetwork architectureRsync Server for Automatic LDAS Backups

I implemented an access point for LDAS to pull data from the TCS lab EPICS frame archive (fb4:/frames) via rsync. The setup is analogous to what is already running at the 40m for automated backups. Here are the implementation details in case we want to replicate this in other W. Bridge labs.

Two lab machines are needed, the frame builder machine (fb4; 10.0.1.156) and a second machine to handle the network interfacing with the outside world (tcs-ws; 10.0.1.168).

1. Set up an NFS mount on tcs-ws to remotely access the frame archive on fb4.

i. NFS server-side setup:

a. Install the required packages

controls@fb4:~$ sudo apt-get install rpcbind nfs-common nfs-kernel-server

b. Add the following line to the file /etc/exports

/frames 10.0.1.168(rw,sync,no_root_squash)

c. Restart the NFS-related services

controls@fb4:~$ sudo /etc/init.d/rpcbind restart

controls@fb4:~$ sudo /etc/init.d/nfs-common restart

controls@fb4:~$ sudo /etc/init.d/nfs-kernel-server restart

ii. NFS client-side setup:

a. Install the required packages

controls@tcs-ws:~$ sudo apt-get install rpcbind nfs-common

b. Add the following line to the file /etc/fstab

10.0.1.156:/frames /fb4/frames nfs rw,nofail,sync,hard,intr 0 0

c. Create the directory for the mount point, then set ownership and permissions

controls@tcs-ws:~$ sudo mkdir /fb4/frames

controls@tcs-ws:~$ sudo chmod -R 775 /fb4

controls@tcs-ws:~$ sudo chown -R controls.root /fb4

c. Mount the new network drive

controls@tcs-ws:~$ sudo mount -a

2. Configure the rsync daemon on tcs-ws.

i. Create a new file named /etc/rsyncd.conf with the following content. These settings match those of the 40m setup.

max connections = 10

read only = yes

log file = /var/tmp/rsyncd.log

list = yes

uid = controls

gid = controls

use chroot = yes

strict modes = yes

pid file = /var/run/rsyncd.pid

 

[ldasaccess]

        comment = For LDAS access to TCS lab frame files

        read only = yes

        path = /fb4/frames

        hosts allow = ldas-grid.ligo.caltech.edu,localhost

ii. Kill, then restart the rsync daemon. The daemon may not be already running.

controls@tcs-ws:~$ sudo kill `cat /var/run/rsyncd.pid`

controls@tcs-ws:~$ sudo rsync --daemon

3. Open a port through the gateway firewall for LDAS to access.

To do this, configure a new port forwarding on the linksys gateway router in the usual way (access the router settings via http://10.0.1.1 from the web browser of any subnet machine). For the TCS lab, the external-facing gateway port 2046 is forwarded to port 873 of tcs-ws (the standard rsync port).

Security is handled by the tcs-ws rsync daemon. Its config file allows outside access to only the hostname ldas-grid.ligo.caltech.edu, and that access is read-only and restricted to the /fb4/frames directory.

4. Testing.

For testing purposes, another outside machine name can be temporarily appended to the "hosts allow" parameter of /etc/rsyncd.conf. For example, I appended my office desktop machine. From the outside machine, the connectability of the rsync server can be tested with:

user@outside-hostname:~$rsync -dt rsync://131.215.115.216:2046/ldasaccess

If successful, the command will return an output similar to

drwxr-xr-x        4096 2017/08/28 16:13:31 .
drwxr-xr-x        4096 2017/11/14 02:30:38 full
drwxr-xr-x        4096 2017/08/28 16:13:38 trend

showing the contents of the frame archive.

  1   Fri Nov 6 20:09:47 2009 AidanLaserLaserTest

 Does this work?

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