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  199   Thu Oct 26 10:45:44 2017 AidanComputingDAQBeam size EPICS channels added to TCS-WS softIoc

See attached photo for how data is written to frames ...

Quote:

These are also being written to frames on FB4.

Quote:

I've added a softIoc to TCS-WS to capture the beam size from the MAKO camera. The IOC is run using ...

controls@tcs-ws:~$ softIoc -S EPICS_IOC/iocBoot/iocfirst/st.cmd &

The st.cmd contains the following text:

controls@tcs-ws:~$ more EPICS_IOC/iocBoot/iocfirst/st.cmd

dbLoadDatabase "/home/controls/EPICS_IOC/db/beamSize.db"

iocInit

 

The db file is:

 

controls@tcs-ws:~$ more EPICS_IOC/db/beamSize.db

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WX")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WY")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_X")

{

    field(PREC,"3")

}

 

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_Y")

{

    field(PREC,"3")

}

 

 

 

Attachment 1: FullSizeRender_10.jpg
FullSizeRender_10.jpg
  198   Thu Oct 26 10:31:31 2017 AidanComputingDAQBeam size EPICS channels added to TCS-WS softIoc

These are also being written to frames on FB4.

Quote:

I've added a softIoc to TCS-WS to capture the beam size from the MAKO camera. The IOC is run using ...

controls@tcs-ws:~$ softIoc -S EPICS_IOC/iocBoot/iocfirst/st.cmd &

The st.cmd contains the following text:

controls@tcs-ws:~$ more EPICS_IOC/iocBoot/iocfirst/st.cmd

dbLoadDatabase "/home/controls/EPICS_IOC/db/beamSize.db"

iocInit

 

The db file is:

 

controls@tcs-ws:~$ more EPICS_IOC/db/beamSize.db

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WX")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WY")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_X")

{

    field(PREC,"3")

}

 

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_Y")

{

    field(PREC,"3")

}

 

 

  197   Thu Oct 26 10:21:28 2017 AidanComputing Beam size EPICS channels added to TCS-WS softIoc

I've added a softIoc to TCS-WS to capture the beam size from the MAKO camera. The IOC is run using ...

controls@tcs-ws:~$ softIoc -S EPICS_IOC/iocBoot/iocfirst/st.cmd &

The st.cmd contains the following text:

controls@tcs-ws:~$ more EPICS_IOC/iocBoot/iocfirst/st.cmd

dbLoadDatabase "/home/controls/EPICS_IOC/db/beamSize.db"

iocInit

 

The db file is:

 

controls@tcs-ws:~$ more EPICS_IOC/db/beamSize.db

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WX")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAMSIZE_WY")

{

    field(PREC,"3")

}

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_X")

{

    field(PREC,"3")

}

 

 

record(ai, "C4:AWC-MAKO_BEAM_POSN_Y")

{

    field(PREC,"3")

}

 

  196   Wed Oct 25 15:34:14 2017 Jon RichardsonComputingFrame GrabberMako CCD Camera Code is Fixed

I fixed a bug in how the raw Mako CCD camera images are being read into memory. The bmp files turn out to have a block memory layout that broke my in-place reader.

  195   Tue Oct 24 15:05:57 2017 Jon RichardsonComputingElectronicsInstalled a Realtime Beam Profiler for the Mako CCD Camera

Aidan found a C demo code for acquiring a single image from the Mako CCD camera and saving it to disk (SynchronousGrab -- aliased on tcs-ws as makoGrab). I wrapped that inside my realtime HWS beam profiler code to create a realtime beam profiler for the Mako camera. The interface is identical to that for the HWS.

The Mako camera is running on the tcs-ws machine (10.0.1.168) and is launched from the console via the command

$stream_intensity_CIT

It is currently configured to write a raw image to the local frame archive every 5 seconds (it prints the write location in the console), which can be disabled by setting the "-d" flag.

  194   Tue Oct 24 10:19:53 2017 Jon RichardsonComputingElectronicsInstalled Maku Ethernet CCD Camera

There is an SDK for the camera with compiled examples. For a really quick image grab from the command line, use the following:

/opt/Vimba_2_1/VimbaC/Examples/Bin/x86_64bit/SynchronousGrab

This will produce a BMP image. We should probably recompile the C code to produce a 16-bit TIFF image.

Quote:

I installed the Maku Gigabit CCD camera driver software on the hws-ws machine. The camera viewer can be opened from the terminal (from any directory) with the command

$ZimbaViewer

and there is also a shortcut icon on the desktop. The camera is ocurrently on the subnet at 10.0.1.157 and is configured to get its IP via DHCP. We can assign it a static IP if we'd like to keep it on the network permanently.

I left the camera mounted on the CO2 laser table. It's connected and ready to use.

 

  193   Mon Oct 23 19:02:42 2017 Jon RichardsonLaserHartmann sensorMitigated Heating Beam Losses

There were known to be huge (65%) heating beam power losses on the SRM AWC table, somewhere between the CO2 laser and the test optic. Today I profiled the setup with a power meter, looking for the dominant source of losses. It turned out to be a 10" focusing lens which had the incorrect coating for 10.2 microns. I swapped this lens with a known ZnSe 10" FL lens (Laser Research Optics LX-15A0-Z-ET6.0) and confirmed the power transmittance to be >99%, as spec'd. There is now ~310 mW maximum reaching the test optic, meaning that the table losses are now only 10%.

Using a single-axis micrometer stage I also made an occlusion measurement of the heating beam radius just in front of the test optic. I moved the 10" focusing lens back three inches away from the test optic to slightly enlarge the beam size. In this position, I measure a beam radius of 3.5+/-0.25 mm at 1.5" in front of the test optic (the closest I can place the power meter). The test optic is approximately 20" from the 10" FL lens, so the beam has gone through its waist and is again expanding approaching the test optic. I believe that at the test optic, the beam is very close to 4 mm.

  192   Fri Oct 13 18:35:29 2017 Jon RichardsonComputingElectronicsInstalled Maku Ethernet CCD Camera

I installed the Maku Gigabit CCD camera driver software on the hws-ws machine. The camera viewer can be opened from the terminal (from any directory) with the command

$ZimbaViewer

and there is also a shortcut icon on the desktop. The camera is ocurrently on the subnet at 10.0.1.157 and is configured to get its IP via DHCP. We can assign it a static IP if we'd like to keep it on the network permanently.

I left the camera mounted on the CO2 laser table. It's connected and ready to use.

Attachment 1: IMG_2287.JPG
IMG_2287.JPG
  191   Fri Oct 13 15:52:41 2017 AidanLab InfrastructureGeneralBroadband mirror BB2-E03 reflectivity at 532nm

I measured the reflectivity of a possible HWS replacement mirror at 532nm. Thorlabs BB2-EO3

Incident power = 1.28mW

Reflected power = 0.73mW

R = 56% at 45 degrees AOI.

 

Attachment 1: IMG_1223.JPG
IMG_1223.JPG
Attachment 2: IMG_1213.JPG
IMG_1213.JPG
  190   Wed Oct 11 20:19:06 2017 Jon RichardsonLab InfrastructureHartmann sensorInitial Characterization of the SRM Adaptive Wavefront Control

Today I made the first characterization measurements of the mocked-up adaptive wavefront control system planned for the signal recycling mirrors.

The Setup

Inside the light-tight enclosure on the center table, I've assembled and aligned a 10.2 micron CO2 projector which provides a heating beam of up to 150 mW incident on an SRM-like test optic. A co-aligned 633 nm probe beam and Hartmann wavefront sensor are used to measure the resulting thermal lens. I've written and installed new software on the machine hws (10.0.1.167) for viewing the wavefront distortion in real time, as shown in the below screenshot. This viewer is launched from the terminal via the command $stream_gradient_CIT

Screenshot of a thermal lens forming on the test optic, as viewed from the real-time software.
To the right is the induced optical path difference across the surface of the test optic, and to the left is its gradient.  

There is also a second utility program for displaying the raw Hartmann sensor CCD image in real time, which is useful for aligning the probe beam. It is launched by the terminal command $stream_intensity_CIT

Initial Thermal Lens Measurements

Lens Formation Time Scale

First, I made a time-resolved measurement of the thermal lens formation on the test optic at maximum heating beam power (150 mW). The lens appears to reach steady-state after 30 s of heating. When the heating beam is turned off, the lens decays on a very similar time scale.

Lens Strength v. Incident Heating Power

Second, I measured the thermal lens strength as a function of incident heating beam power, which I measured via a power meter placed directly in front of the test optic. Below is the approximate maximum optical path difference induced at several heating beam powers.

Incident Power (mW) Maximum Optical Path Difference (nm)
150 +/- 15 35 +/- 5
85 +/- 2 25 +/- 5
50 +/- 4 15 +/- 5
10 +/- 1 5 +/- 5

The above optical path differences are approximate and were read-off from the live display. I recorded Hartmann sensor frame data during all of these measurements and will be analyzing it further.

  189   Wed Oct 11 19:14:16 2017 Jon RichardsonComputingElectronicsReplaced TCS Monitor

I replaced the dead 24" monitor on the work bench, which is connected to the video multiplexer. Mike Pedraza was kind enough to bring us us a new one and take away the old one.

  188   Thu Sep 21 18:56:53 2017 awadeMiscBorrowedBorrowed thorlabs power meter

Borrowed thorlabs power meter on 21 Sep 2017.  It is on the south table of the ATF lab.

  187   Thu Jul 13 10:11:57 2017 awadeElectronicsBorrowedBorrowed newport TrueRMS Supermeter

I lent your fancy Newport TrueRMS Supermeter with the thermocouple plugs on the top to the SURF student Jordon.  He has it in the cryo lab or the EE workshop with one of the PSL lab temperature probes.

Attachment 1: 2017-07-13_10.06.28.jpg
2017-07-13_10.06.28.jpg
Attachment 2: 2017-07-13_10.06.29.jpg
2017-07-13_10.06.29.jpg
  186   Mon Jun 5 16:41:59 2017 AidanLaserHartmann sensorHWS long term measurement results.

The data from the long-term measurement of the HWS is presented here. The beam envelope moves by, at most, about 0.3 pixels, or around 3.6 microns. The fiber-launcher is about 5" away from the HWS. Therefore, the motion corresponds to around 30 micro-radians (if it is a tilt). The beam displacement is around 4 microns.

The optical properties change very little over the full 38 days (about 2 micro-radians for tilt and around 2 micro-diopters for spherical power).

The glitches are from when the SLED drivers were turned off temporarily for other use (with the 2004nm laser).

Attachment 1: HWS_envelope_long_term.pdf
HWS_envelope_long_term.pdf
Attachment 2: HWS_optical_parameters_long_term.pdf
HWS_optical_parameters_long_term.pdf
Attachment 3: HWS_envelope_long_term_mm.pdf
HWS_envelope_long_term_mm.pdf
Attachment 4: IMG_9836.JPG
IMG_9836.JPG
  185   Wed May 24 09:58:17 2017 AidanElectronicsElectronicsTemperature sensor batteries swapped in TCS Lab

I noticed that the TCS lab temperature sensor batteries died. Apparently they died two days ago. I swapped in some new batteries this morning.
 

  184   Wed Apr 26 15:29:25 2017 AidanElectronicsHartmann sensorLong term test of fiber launcher

I've started a long-term measurement of the HWS fiber-launcher. I'm interested in seeing how stable the output is. The HWS is currently running in the following configuration:

  • SLED: QFLD-635-1S (635nm, 1mW) - current driver set to 38.02mA, thermistor set point = 10.778kOhm
  • SLED coupled to patch cable
  • Patch cable coupled to Newport fiber launcher FPR1-C1A which contains a FPH-CA4 fiber optic chuck (FC/APC connector). All grub screws are tighten on this (two for holding chuck, one for roll motion, one for X translation lock and one for Y translation lock)
  • Output of fiber hits a 100m focal length lens (SPX043AR.16 BBAR 0.65 - 1.0um) placed approximately 100mm from the fiber output
  • Output of lens is projected approximately 125mm onto the HWS where it is centered on the HWS plate

The HWS is currently running at 57Hz. The HWS code is running on HWS (10.0.1.167). It is the same as the site code with some modifications to determine information about the Gaussian beam envelope. The following data is written to file on the HWS machine in files containing 10,000 cycles. Each cycle (or row) the following data is recorded:

  • GPS TIME
  • PRISM_X
  • PRISM_Y
  • SPHERICAL_POWER
  • CYLINDRICAL_POWER 
  • Envelope peak intensity
  • Envelope X centroid
  • Envelope Y centroid
  • Envelope X width
  • Envelope Y width

These are saved to files on the HWS machine: ~/framearchive/C4/HWSlongterm/<GPSTIME>_CIT_HWS.txt

  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.

 

  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.

Attachment 1: IMG_8148.JPG
IMG_8148.JPG
  181   Mon May 13 14:09:02 2013 ZachComputingDAQC2ATF model rebuilt

 ATF:1812

  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

  179   Fri Jun 29 15:51:24 2012 Aditi MittalMiscLIGO 3GSummary June 28 and 29, 2012

 -Discussed the project outline for next 6 weeks.

-made a write up for the tasks. (attached)

-Analyzed the variation of temperature of the test mass with input power for different lengths of the shield. 

Attachment 1: pipelength_power.xlsx
Attachment 2: 6week_plan.doc
  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

 

  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

  176   Tue Jun 26 17:55:44 2012 Aditi MittalMiscLIGO 3GSummary June 26, 2012

- Discussed the further project with Dr. Brooks.

-Tried to derive formula for the test mass inside cryogenic shield(infinitely long shield from one side)

 

 

 

  175   Thu Jun 21 18:35:44 2012 Aditi MittalMiscLIGO 3GSummary June 21, 2012

 -Updated 3 week progress report with new additions and deletions.

-Attended LIGO lecture which was very interesting and full of information.

  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

 

  173   Thu Jun 21 11:16:27 2012 Aditi MittalMiscLIGO 3GSummary June 19 and 20, 2012

 -Attented LIGO orientation meeting and safety session.

-Prepared 3 week report

 

Attachment 1: temp_of_test_mass.png
temp_of_test_mass.png
  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)

 

Attachment 1: TS_model_deformation_line_graph_2W_10%.png
TS_model_deformation_line_graph_2W_10%.png
Attachment 2: TS_model_deformation_line_graph_2W_10%_sym.png
TS_model_deformation_line_graph_2W_10%_sym.png
Attachment 3: TS_model_deformation_line_graph_2W_10%_antisym.png
TS_model_deformation_line_graph_2W_10%_antisym.png
Attachment 4: TS_model_deformation_contour_graph_2W_10%.png
TS_model_deformation_contour_graph_2W_10%.png
Attachment 5: HTSM_model_deformation_contour_graph_2W_10%.png
HTSM_model_deformation_contour_graph_2W_10%.png
  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.

  170   Mon Jun 18 23:42:39 2012 Aditi MittalMiscLIGO 3GCryogenic Shielding

 -Read about blue team design for maximum power budget.

-Read third generation talks to get a better understanding of the work. 

  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)

 

  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)

Attachment 1: SIS_Outputs.txt
Unchanged field:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   FP cavity modal analysis using cold optics parameters
 
ROC(ITM) = 1934, ROC(ETM) = 2245, Cavity lenggth = 3994.499999672, total Gouy = 2.7169491305278
Fval(ITM) = -4297.7777755379, OPL(ITM) = 0.13793083662307, Fval(ETM) = -4988.8888885557
waist size = 0.01203704073212, waist position from ITM = 1834.2198819617, Rayleigh range = 427.80682127602
 
Mode parameters of cavity fields
ETM AR (out base) : w = 0.0619634      R = 1548.276       z  = 1519.925       z0 = 207.583        w0 = 0.008384783   
... 138 more lines ...
Attachment 2: Assymetric_Heating_Line_Graph.png
Assymetric_Heating_Line_Graph.png
  167   Thu Jun 14 05:37:30 2012 Aditi MittalMiscLIGO 3GSummary June 13, 2012

-Derived formula for manual calculation of temperature due to total influx.

-Compared the results by COMSOL and by the formula.

  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)

  165   Mon Jun 11 20:53:31 2012 Aditi MittalMiscLIGO 3GSummary June 11, 2012

 -Continued with the same cryogenic model created and varied the length of  outer shield and studied the temperature variation inside.

-Compared the temperature difference given by COMSOL with manually calculated one.

  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

 

  163   Fri Jun 8 23:51:13 2012 Aditi MittalMiscLIGO 3GSummary June 8, 2012

-Created a COMSOL model for cryogenically shielded test mass with compensation plate.

-Analyzed the behavior of the model in different size configurations.

  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)

 

  161   Thu Jun 7 23:24:56 2012 Aditi MittalMiscLIGO 3GSummary June 7, 2012

-Created a COMSOL model for variation of temperature in two mass system.

-Used the above model for cryogenic conditions.

-checked it analytically.

  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

  159   Thu Jun 7 00:23:11 2012 Aditi MittalMiscLIGO 3GSummary June 5 and June 6, 2012

 June 5

-Discussed the actual project outline 

-Installed Comsol on the system

-Learned the basics of Comsol with the help of tutorials available on 40m wiki

and others.

 

June 6

-Made few simple models in Comsol 

-Studied LIGO GWADW slides for a better understanding of the project.

-Setup SVN to access remote 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.

  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

  156   Tue Nov 29 09:13:49 2011 ranaMiscLIGO 3GSwitching from CO2 to shorter wavelength solid state laser

 Around a year ago, Phil and I discussed the possibility of using an OPO to possibly generate our own laser beam at ~2 microns for TCS. This was to avoid all of the usual hassle of the 10 micron CO2 laser.

As it turns out, the 1.5-3 micron range doesn't have enough absorption in fused silica: the absorption depth would be basically the whole thickness of the optics and this is not so useful when trying to correct surface heating.

During my recent trip to JILA, Jan Hall mentioned to me that it should be possible to operate instead at ~5 microns, where laser technology may be solid state and where we can use Si:As detectors instead of the inefficient HgCdTe ones which we use now.

JWST, in partnerships with industry, have developed some Si:As detectors:  http://www.jwst.nasa.gov/infrared.html   

Some internet searching shows that there are now several laser technologies for the mid-IR or MWIR range. Some are <1 W, but some are in the ~10 W range.

Of course, its possible that we'll switch to Silicon substrates, in which case we need to re-evaluate the goals and/or existence of TCS.

  155   Fri Sep 2 21:41:01 2011 AidanElectronicsHartmann sensorRestarting long term test of QFLD-950-3S

9:40PM PDT - I've just restarted the long term measurement of the Hartmann sensor noise with the QFLD-950-3S.

 

  154   Fri Sep 2 14:41:48 2011 AidanComputingHartmann sensorQFLD-950-3S long term test finished

I ran a test of the HWS with the QFLD-950-3S for 5 days. The test was terminated as we need to disconnect all the cabling and tidy up all the computers in the lab.

  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.

 

  152   Mon May 30 20:11:27 2011 AidanLaserHartmann sensorHartmann sensor lever arm calibration

 I ran through the procedure to calibrate the lever arm of the Hartmann sensor. The beam from a 632.8nm HeNe laser was expanded to approximately 12mm diameter and injected into a Michelson interferometer. The Hartmann sensor was placed at the output port of the Michelson.

  1. I tilted one of the mirrors of the interferometer to induce a prism between the two beams at the output. This created about 135 vertical fringes on the CCD.
  2. With the Hartmann plate removed, I recorded the interference pattern and took its 2D FFT. There was a peak in the Fourier transform about 134 pixels from the DC level. 
  3. This next part is questionable ...  I centroided the frequencies around the peak in the FFT to try to determine the spatial frequency of the fringes to better than the bandwidth of 1/1024 pixels^-1 (yes, they're strange units). This is, probably acceptable at improving the accuracy of the frequency measurement if it is known that the signal is a generated by a pure sine wave in the spatial domain - this is not an unreasonable assumption for the output of an interferometer. Anyway, the peak fluctuated around 133.9 units from DC by around +/- 0.1 units.
  4. The prism between the two beams is the measured spatial frequency (measured as 133.9 oscillations across the CCD) multiplied by the wavelength and divided by the width of the CCD (= 1024 x 12um). In other words, the prism is the ratio of the wavefront change across the CCD divided by the diameter of the CCD (= 6.895 +/- 0.005 mrad)
  5. Next, I inserted the Hartmann plate, blocked one of the beams and recorded the spot pattern. I then blocked the other beam and unblocked the first and recorded another spot pattern. 
  6. The mean displacement between the spot patterns was calculated. Due to a fairly noisy intensity distribution (the 2" mirrors were AR coated for 700-1000nm and hence there were some stray beams), the mean displacement was relatively noisy - about 5.60 pixels with a standard deviation of around 0.3 pixels and a standard error of around 0.01 pixels ( = 67.2 um)
  7. The lever arm is equal to the mean displacement of the spots divided by the prism. In this case, 9.75 +/- 0.02 mm
  8. I removed the Hartmann plate and confirmed that the FFT of the fringes from the IFO still had a peak at 133.9 +/- 0.1 units. It did.

 

  151   Mon May 30 10:53:00 2011 AidanLaserHartmann sensorDefocus vs time

 I've had the output from a fiber projected about 400mm onto the Hartmann sensor for around 5 days now. (The divergence angle from the fiber is around 86 mrad).

I played around with the temperature of the lab to induce some defocus changes in the Hartmann sensor. The system is mostly linear, but there are relatively frequent jumps in the defocus of the order of 1E-4 m^-1. This may be due to a number of things - the Hartmann plate may be moving, the fiber holder may be shifting back and forth, there may be some issue with the source wavelength shifting.

  • A change in defocus, dS, of around 1E-4 m^-1 from a point source at 400mm from the Hartmann plate (dS/dx = -1/x^2), corresponds to a change in the end position of the fiber of around 16 microns. Seems a little big ... unless it's not secured properly ...
  • Also the defocus vs temperature slope is different from what James measured last year. There is an additional -4E-5 m^-1 K^-1 due to the expansion of the stainless steel table moving the point source further or closer to the Hartmann plate. That leaves about -3E-4 m^-1 K^-1 for the Hartmann sensor. This is roughly twice what James measured last year. 

Sun 30th May 2011 - 11:40AM - the z-axis control on the NewFocus 9091 fiber coupling mount was not tightened. I tightened that to secure the control.

Attachment 1: HWS_defocus_vs_temperature.pdf
HWS_defocus_vs_temperature.pdf
  150   Thu May 26 11:56:46 2011 AidanElectronicsLaserGreen Laser Pointer beam profile

This measurement was made with the Thorlabs DCC1545M-GL camera with an RG850 3mm long-pass filter over the CCD.

The beam radius (w) is 191 pixels, where the beam intensity = exp[-2 (x/w)^2 ]

The pixel size is 5.2um. Hence the beam size is 993.2um, which is basically near enough to 1mm radius.

 

Attachment 1: green_laser_pointer.bmp
Attachment 2: green_laser_pointer.pdf
green_laser_pointer.pdf
Attachment 3: Screen_shot_2011-05-26_at_12.28.20_PM.png
Screen_shot_2011-05-26_at_12.28.20_PM.png
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