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  Richardson Lab Experimental Log, Page 5 of 12  Not logged in ELOG logo
ID Date Author Type Categorydown Subject
  196   Tue Aug 8 16:47:11 2023 SophiaUpdateScripts/ProgramsUpdate on Dynamic CSD and PSD Plots
We have fixed our rapid plotting error, and realized that this has not been affecting our data intake! Below is a video of the code progressing, alongside grabbed images of the raw data. The data is now continuous, and performs as we expect. Next, I plan to add a widget which will dynamically show the peak values instead of them just being printed in the terminal after each iteration. (Ignore the red box-- it was from me struggling with a now fixed issue).
  206   Tue Aug 15 10:35:00 2023 SophiaUpdateScripts/ProgramsUpdate on Laser Noise Data Collection and Analysis: Dynamic CSD and PSD Plots
I have successfully added a button to my graphics, but it has posed a strange issue with the CSD and PSD values. When I plot my original code, I still see the pretty peaks that I was getting originally, while my new code (as shown in the video and in the last screenshot) is giving me more of a line. In my code that gives the peak values, the CSD values also tend to fluctuate in this new code as well (shown in the first screenshot), before returning to the real value. I think that there is a problem with the averaging and am hoping to solve this issue today with Tyler. This is good progress though!
  207   Tue Aug 15 13:32:37 2023 SophiaUpdateScripts/ProgramsUpdate on Laser Noise Data Collection and Analysis: Dynamic CSD and PSD Plots
I have now fixed all issues that I was having this morning, and have added text boxes which show the peak values of both PSD's and the CSD alongside the graphs. They also update continuously with the graph. This is shown in the top image. The laser was driven at 400Hz, and had 0.5V peak to peak voltage, both of which appear correctly in the below graphs. Now that the code is almost fully working (we will finish debugging the screenshot method later today), our plan tomorrow is to drive the laser and see how the code performs with it. The below graph is from us driving the function generator at 100Hz to test the range. Update: Bottom graph is new version of graphs with better distribution of both graphs.
  249   Mon Oct 30 11:03:56 2023 TylerUpdateScripts/Programs 

FLIR: After some adjustments, the plot generated from the FLIR measurements look much more symmetric (see attachment). There are more included grid points, which smooths out the curve as compared to last week.

Red Pitaya: It looks like a new OS update was released for the RP, which includes a new Python API (was previously only available in C). I'm going to try and update the one we have currently running in lab.

  317   Tue Feb 6 22:40:25 2024 MichaelUpdateScripts/ProgramsLong Crab 1 Design Created In Gtrace
Worked on and completed the python code for the simulation of the Long Crab 1 layout for Cosmic Explorer basing off of Pooyan's original work with the Crab 1 layout. From here I'll look into creating the shoelaces layouts.
  376   Fri Jun 14 13:32:13 2024 LiuUpdateScripts/ProgramsCOMSOL simulation on rectangular heater elements design

I have been looking at the feasibility of an alternative heater element design for FROSTI that replaces the original ring-like heater elements with n rectangular elements with straight edges. They form an n-sided regular polygon that could well approximate the original annular ring if n is large enough. This eliminates curved surfaces requirement for the heater elements, which was the source of the many month production delay for the prototype parts.

This design was implemented in COMSOL, shown in the attached. From the face on view, each element has a trapezoid shape with straight edges. The edges between neighboring elements are parallel, with a space of 2 mm in between them.

The ray tracing and thermal analysis obtained from COMSOL are shown in the attached pdf.

In particular, the 2D irradiance profiles were obtained from the ray tracing (so far from the front heating surfaces only). The 1D radial profiles were integrated and shown in the attached. The power delivery efficiency for the original ring-like heater element design is integrated to be roughly 65%, for comparison. The plot also shows the radial irradiance profiles for three different straight-edge designs, which correspond to 16 edges, 18 edges, and 24 edges. We see that with the straight-edge designs, the irradiance profiles stay in a good Gaussian shape. In addition, with a larger number of edges, the power efficiency increases, but is always less than the case for the optimized ring-like design.

The thermal distortions for the TM were also obtained from COMSOL, using the irradiance profiles at the TM HR. As shown in the attached, with the straight-edge design, the effects on the thermal lens OPD and the HR surface deformation are similar to the ring design, but with less severe edge roll-off for instance.

  380   Fri Jun 21 11:47:30 2024 LiuUpdateScripts/ProgramsCOMSOL simulation on alternative straightened heater elements design

In the previous post, we saw that for the heater element design with straight edges in replacement of the current eight-element ring-like design, it provides the similar Gaussian-like irradiance profiles, but with smaller power delivery efficiencies, as shown in the plot. This turned out to result in similar but less prominent thermal effects.

They only differ from the original baseline design by a source power rescaling, however, as shown in the plot, where we see the power-rescaled irradiance profiles for the straight edge designs are close to that for the ring design. The resulting temperature profiles and thermal distortions are shown in plot and plot. The thermal effects for the 16 straight-edge design with renormalized source power for instance are strikingly similar to that for the original ring design.

An alternative straightened heater element design has also been investigated with COMSOL FEA simulation. As shown in the attached, in this new design each heater element component is cut with multiple straight edges but remains connected, shown in the same colors (green and red). In the example, four straight edges are cut from each of the four heater components (4x4=16 edges in total). There is no spacing between the neighboring edges from the same element component, but the edges from different components are separated by 2mm, as can be seen in the attached. This new N-in-one straight edge design offers similar irradiance compared to that for the evenly-spaced N-sided regular polygon straight edge design with the same number of edges, as shown in the plot. It however has fewer heater components, four in this case, which makes it easier to implement in assembly and wiring, and less vulnerable to electrical and thermal shorts with their fewer heater element pins.

  387   Thu Jun 27 11:09:14 2024 LiuUpdateScripts/ProgramsStraight edge STEP files and ray loss analysis

Drawings and CAD models of the straight-edge designs are exported, and are visualized in SOLIDWORKS. Two are attached. One is a single edge of the evenly spaced polygon design with 16 edges, and the other is the 8x2 design, with two neighboring edges grouped together to replace the original single curved heater.

For the straight edge design in COMSOL, ray power detectors were placed at the heater's front surface. The irradiance is shown in figure. The amount of light rays deposited back to the heater is small when close to the center, where it is closer to the original ring. The ray power increases as we move further away from the center toward the edges. In addition, the total power integrated at the heater's front surfaces is about 21% of the original heater's emitted power. This could account for the power efficiency difference between the straight edge design and the ring design, as shown in plot for instance.

  447   Mon Sep 23 15:11:21 2024 TylerUpdateScripts/ProgramsEffective Emissivity Analysis and RIN Update

A quick update on the effective emissivity analysis for the CIT FROSTI testing:

I was able to (roughly) match the OPD data to a referenced COMSOL model, with an applied power of 12.6 W (as seen below). However, when changing the emissivity of the ETM in COMSOL, the dT profiles do not seem to change much. I am not sure as to why this is the case at the moment, and will continue to look further.

Additionally attached are the current RIN measurements of the FROSTI prototype. Shown is the PSDs of both channels, in reference to their individual backgrounds.

  521   Sun Feb 23 16:00:07 2025 Luke UpdateScripts/ProgramsRingheater modeling Update

These are some plots:

The first shows the convergence of the 02 mode reducing the size of the mesh. The second shows the the numerical error of the zernike.

The first is found by sweeping a parameter that changes the size of the mesh. The HR surface was set to half a cm for all values.

The second by taking the inner product of a zernike mode with its self and calculating its deviation from pi for varying fineness of the mesh.

  541   Sun Mar 23 15:39:06 2025 Luke JohnsonUpdateScripts/ProgramsRingheater Location optimization
Attached are some plots that show a new parameter sweep with a finer mesh then before. I have also been able to get a heatmap of power of HOMs in a very simple finesse model.
  543   Mon Mar 31 11:26:45 2025 Luke JohnsonUpdateScripts/ProgramsHeatmaps of power delivery performance
These plots show the required temperature to release 100W of power and the efficiency of a particular configuration with half-width w and distance away from the barrel z. I want to add to these heat maps a limit line that has restricts the proximity of the reflectors from the barrel.
  550   Tue Apr 8 12:15:59 2025 Luke UpdateScripts/ProgramsUpdated optimization plot
  557   Tue Apr 22 08:00:39 2025 Luke UpdateScripts/ProgramsThermal optimization modeling 40kg

I have redone the width and location optimization with a 40kg test mass. This was to see where the nominal ring heater would fall in this optimization map see attached.

There are two concerns I have with this modeling:

  1. I am using normalized power only imparting 1W, which may effect the single pass scattering used for optimization.
  2. I am only looking at the surface deformation and I believe that looking at OPD may also be something that is important to consider. 

Note z_RH is measured from the HR surface and w_RH is the half width of the target plane

  561   Fri Apr 25 09:09:03 2025 Luke UpdateScripts/ProgramsUpdate to optimization plots
I have calculated the curvature of the surface plots and created a heat map out of the data. I have also created a contour plot of them together. It is very rough and the artifacts at small w make it hard to read. I am planning on excluding that data and replot them. In the meantime I have created a temporary function that balance the two values. (log_10(curvature/HOMscattering))
  562   Fri Apr 25 19:18:10 2025 Luke UpdateScripts/ProgramsNew optimization plots

I have created two more plots. One on the transmitted power for a specific configuration. This was done by taking the product of the efficiency and the power released by surface area of the source plane for a configuration assuming it is at 300C. The second is a plot of how close the reflector is to the test mass I have included a contour line at 2mm the nominal proximity constraint. Both of these plots are generated for a 2cm wide target plane.

Somethings of note: Because the proximity requires no modeling and can be determined purely mathematically it is easy to re-generate this plot of other target widths. If you increase the target width the proximity contour moves upward and downwards if reduced.

  569   Sun May 4 18:17:45 2025 Luke UpdateScripts/ProgramsRingheater modeling Update

Slides

I have changed some properties of the thermal model and am re-running the thermal sweeping

I have also been messing around with making a logo

  575   Sun May 11 19:36:42 2025 Luke UpdateScripts/ProgramsNew optimization plots

Slides

I have re-run the optimization plots with the changes mentioned last week. 

I have added the heat maps of the HOM scattering from HR deformation and the HOM scattering due to the OPD difference as well as the curvature actuation of the surface. 

  581   Mon May 26 11:15:28 2025 LukeUpdateScripts/ProgramsUpdate to optimization plots
I have created some new optimization plots. I have also started on a model like the previous Desmos model, but in python.

Slides

  584   Mon Jun 2 09:45:06 2025 Luke UpdateScripts/ProgramsRingheater modeling Update

Slides

I have added some slides to my meeting updates. The updates include: my choice in position and width, some figures I have added to my write up, and what I think my immediate steps are to wrap up.

I have also made a new FROSTI model that conducts its raytracing in real time. Something that was severely lacking in the previous model.

  134   Tue Jun 27 14:04:42 2023 Sophia A. UpdateMeasuring Noise in InterferometerInterferometer set up and connection to red pitaya
Today we (Sophia and Tyler) constructed the set-up for the electrical noise calculation that I will be conducting this summer. I have included images of the setup below. Our system is effectively a green laser, that feeds into a type of polarizer, then into a beam splitter which sends the laser light down two arms into detectors. We started by connecting the detectors to an oscilloscope to determine whether the signal will exceed 1V, as the red pitaya (our planned data collection device) cannot receive signals with a higher voltage than 1V. We spent most of our time calibrating the oscilloscope and fine-tuning the set-up so that we would have approximately equal voltages in each arm of the interferometer. Once confirming that the output voltage would not meet or exceed 1V, we switched from an oscilloscope to the red pitaya for our measurements. Now that the system is set up, we will be able to run code in the red pitaya interface that will run an FFT on the signal, and then do noise analysis from there.
  10   Wed Aug 17 16:04:30 2022 Phoebe ZylaSummaryLoreTesting the Cartridge Heater and Collecting FLIR Data

We have tested the heater to find emissivity, mounted the heater system to the optical table, and have taken irradiance maps of the heater projected onto the screen.

The heater's emissivity was determined by using a thermocouple in conjunction with the FLIR's temperature calibration. To attach the thermocouple to the heater initially, I used Kapton tape and ran both the wires of the heater and the thermocouple through the heater bridge. This allowed for the heater to rest on an optical post and be observed without anyone directly holding it, but there were some measurement issues. The thermocouple had a very wide range of temperatures it was reading, which may have been due to intermittent contact or a short between the two legs of the thermocouple. To solve this and make the temperature measurements more stable, we pried apart the two ends of the thermocouple (to ensure there was no short) and put tape on either side, leaving the end connection bare. This was then taped to the heater, and the thermocouple was much more stable. We also used a K-type thermocouple that has an adhesive tape on it already, which assisted with the intermittent contact as well. With the thermocouple measuring the temperature of the heater, we could point the FLIR directly at the heater and calibrate the emissivity until the FLIR and the thermocouple agreed. Cassidy's emissivity calculator was also used, as I could input a temperature and observe what the emissivity of an area was based on that temperature. We found the emissivity of the heater to be 0.57.

As a note, when observing the heater with the FLIR, it appeared that there was a hot spot in the center, where the Kapton tape sat. Because the Kapton has a different emissivity than the 304 stainless steel of the heater, the FLIR will read it as having a different temperature than it actually does. When using the FLIR in the future, be sure to ascertain whether there is a temperature difference somewhere or if there may be different emissivities.

Additionally, the first heater that I used was taken to a very high temperature and oxidized. The emissivity of this oxidized heater is not known, but could be good information for knowing how oxidation affects these heaters specifically.

To mount the heater system in front of the screen, I used 1/2'' optical posts and the mount I designed using COMSOL's CAD program. The heater was originally 2.5 inches away from the screen, and has since been moved back by an additional two inches so that we could observe the heater side of the screen with the FLIR. We wanted to see what temperature the heater side of the screen was when irradiated by the heater, and how that compared to the camera side of the screen. When the heater ran at 1.12 W of input power, the heater side of the screen had a max temperature of around 29.7 C, and the camera side of the screen read at about 29.5 C. This means that there is very little thermal loss between the two sides of the screen, and any insulation that the screen's adhesive may have is largely negligible. Additionally, the camera was placed at an angle and undetermined distance for these tests, confirming that the temperature measurements compensate well/don’t depend on changes in angle or distance between the camera and the screen. However, there was spots on the back of the screen that the camera was measuring as hot spots where there shouldn’t have been any. I have included an example below. It would be useful to run a test where the camera is directly on the back of the screen without the heater to characterize the screen and see if the hot spots are physically present on the screen or if this is an artifice of the camera because of something like angle of viewing.

Taking irradiance maps of the screen was straightforward. After checking that the emissivity of the screen is 0.99 by viewing it at room temperature, we monitored the max temperature while slowing increasing the wattage the heater was running at. There is not a large change until the heater is at around 95 C, at which point the screen began to rise in temperature from 27 C to 28 C. We took measurements of this while the heater was 2.5 and 4.5 inches away from the screen. The irradiance map has a very symmetrical and circular shape, but does not have the ring pattern that we expected. There may be a few reasons for this: there could be some conduction between the two sides of the screen that is causing the pattern to spread further, the heater setup may not be as ideal as it was modeled to be, or there could be a different, unknown issue.

TO DO:

- It would be useful to run a test of the camera in multiple different positions to ensure our conclusion that the camera’s measurements don’t depend on angle or distance (or that these factors are well accounted for in the current temperature calculations) is correct.

- Measure the back of the screen straight on to identify bright spots and possible reasons as to their appearance.

- Recalibrate camera to ensure it is still correct after testing in multiple positions.

- Take another irradiance map of the screen at a higher input power, as well as moving the heater close/further away to try and replicate the COMSOL irradiance maps. It would be useful to also redo the COMSOL modeling at lower powers and variable distances.

Pictures included of full table setup, the heater mount, the heater with Kapton tape attaching the thermocouple as well as FLIR's measured irradiance map.

  274   Tue Nov 21 14:47:24 2023 TylerUpdateLore1129 Workbench Assembly Update 1

[Tyler, Shane, Mohak, Cynthia, Luke, Michael, Luis]

Started assembly of the workbench equipment today. We completed the stools, and have constructed the frames of each workbench. All that needs to be added are the tabletops and the top shelves, which will be done on Monday.
  278   Mon Nov 27 14:22:30 2023 TylerUpdateLore1129 Assembly Update
[Tyler, Michael, Luke, Cynthia]

The tabletops have been attached to the workbench frames. Unfortunately, one of the tabletops came out of the box with a large scratch and small dent in the middle. One of the electric top shelves is ready to be attached to the undamaged table, but the other is yet to be opened. Assembly will be completed Wednesday morning.

  281   Thu Nov 30 13:50:32 2023 TylerUpdateLoreWorkbench Assembly Completed
[Tyler, Luke, Aiden]

The workbenches are now completely assembled and put into their final places. Additionally, the tool chest has been moved.

  321   Tue Feb 13 01:26:30 2024 PeterUpdateInterferometer SimulationsCARM Power Simulations
Cao's simulations of the circulating power and gouy phase through a single arm cavity of the interferometer have been reproduced. Images of the plots can be shown in the pdfs attached. There are approx. 400 lines in this code (scenario_3_carm) that produces these plots. This code also calls on a separate code source file (thermal_models) that defines many of the functions used in this main simulation. The thermal_models file consists of over 1000 lines. More work needs to be done to fully understand and document the scripts.
  322   Tue Feb 13 04:05:32 2024 MichaelUpdateInterferometer SimulationsShoelaces 1 Layout Simulated in GTrace
I've worked on and have completed a first simulation of Cosmic Explorer's Shoelaces 1 layout. This is based off of Pooyan's original work with Gtrace much like the Long Crab 1 layout I worked on last week. This layout will allow me to quickly created the alternate shoelaces layouts. I've included an image of the dxf, and a desmos model for reference.
  324   Tue Feb 13 12:26:23 2024 TylerUpdateInterferometer SimulationsBS Code Update

I reproduced Cao's CE beamsplitter code (see below for example plots). I received the current info on the beamsplitter parameters for A+ and A# from GariLynn also. The next steps are to perform a similar power loss analysis on the anticipated A# beamsplitter.

  326   Tue Feb 13 13:02:41 2024 PooyanUpdateInterferometer SimulationsCacity sacn of Fabry-Perot
Created a simple model of Fabry-Perot cavity in SIS, and did a cavity scan. Total power in the cavity, 00 mode, and HOMs is measured.
  334   Wed Feb 21 23:15:07 2024 MichaelUpdateInterferometer SimulationsLong Shoelaces 1 Layout Created in Gtrace and Fixed Ghosting in Beamsplitter
I have created the long shoelaces 1 layout for cosmic explorer using gtrace, a slight modification from the shoelaces 1 layout design. I also modified the simulation code slightly to remove ghosting effects in the beamsplitter. Originally the python code specified that the HR and AR sides of the beamsplitter both have the same transmission/reflection. I modified this to the ideal case of: Refl_AR = 0, Trans_AR = 1. I have attached two images below to show the before and after effect of this modification.
  342   Tue Feb 27 03:26:28 2024 MichaelUpdateInterferometer SimulationsReverse aLIGO Layout Created in Gtrace
I've created the simulation for reverse aLIGO layout in gtrace. Attached are the desmos model and the output dxf file. From here Pooyan and I plan to create a brief report of our progress to the CE optical design group.
  343   Tue Feb 27 09:06:29 2024 Cynthia UpdateInterferometer Simulationscavity scan with higher order input laser
I performed a few cavity scan with the inputing laser with a different mode (not pure 00). For each laser I included a graph for just plotting the order with highest power (for example 1st order laser input the first plot only scanned for 1st order in that cavity), and I have also included a graph scanning for order 1-10.
  357   Sun Apr 7 13:42:51 2024 MichaelUpdateInterferometer SimulationsUpdate on status of gtrace project
[Pooyan, Michael]

After meeting and discussing the current state of our work with Prof. Fulda a few weeks ago, we have decided that the best next step for the gtrace project is its integration into finesse work. Our first step towards this integration involved creating a sequential beam trace in contrast to the previous non sequential gtrace simulations. A sequential beam trace not only allows for faster runtimes of the simulation (<1 second) but also allows for more direct reading of certain beam parameters (beam size, gouy phase, and angle of incidence). The sequential model was created alongside a yaml output which provides values of parameters, now including the angle of incidence on a mirror.

Last Monday, Pooyan gave a report to the Cosmic Explorer optical design team on the current state of our project and the ultimate goal of our work. During the same meeting another group working in the optical design team presented their own work with gtrace and optical design, focusing more on optimization of parameters based on desired beam sizes at each mirror. It might be a good idea to begin attempting to bring our individual projects together to allow for collaboration and further developments.

Currently, only the crab1 layout has a sequential trace model. Pooyan is currently working on creating a finesse model for crab1 to serve as a proof of concept for how gtrace could be integrated with finesse by providing useful values such as angles of incidence.

  358   Mon Apr 8 14:43:29 2024 PooyanUpdateInterferometer SimulationsSIS update single and coupled cavities
[Pooyan, Cynthia]

Attached is a brief recap PDF file. A video file showing separate HOMs plots for the cavity scan with ETM08 surface map is also attached.

The codes are available at https://git.ligo.org/uc_riverside/hom-rh/-/tree/main/SIS

  359   Mon Apr 8 14:57:41 2024 Cynthia, PooyanUpdateInterferometer Simulationsperformed cavity scans for O4 O5, and coupled cavity
  361   Mon Apr 15 15:25:10 2024 CynthiaUpdateInterferometer Simulationsprogress on simulation so far
  363   Mon Apr 22 15:06:33 2024 Cynthia UpdateInterferometer Simulationscavity scan update
[Cynthia,Pooyan] Completed some simulations injecting 0-10th order modes. Some graphs will be used for the poster after some further titles, axis, and range adjustments.
  374   Mon Jun 3 14:59:44 2024 CynthiaUpdateInterferometer SimulationsCreated cavity scan with LG modes
  381   Mon Jun 24 14:28:51 2024 Cynthia UpdateInterferometer SimulationsSIS cavity with thermal effect
tried to run a cavity scan with thermal deformation and ring heater for ITM04 ETM08 (aLIGO mirrors). Not sure about the accuracy of the graph as there is some commands that still need to verified.
  391   Mon Jul 1 11:45:45 2024 SidUpdateInterferometer Simulations 
Progress update: Most of last week was spent getting set up with SIS, and learning how to do basic simulations. The goal for this week is to begin reproducing the methodology from T2000338. I have begun with studying perturbations to mirror curvature and position in a simple FP cavity, but thus far have been unable to get the same results.
  392   Mon Jul 1 15:19:42 2024 Cynthia UpdateInterferometer SimulationsO4 and O5 mirror cavity scans with thermal effect
  393   Fri Jul 5 13:17:44 2024 LiuUpdateInterferometer SimulationsFour-quadrant FROSTI-like RH for astigmatic thermal actuation for CE optics
In the CE corner layout design and down selection study, interferometer layouts with large incidence angles on some of the curved optics are being considered, such as the folding mirrors in the "long crab". This however generates astigmatic beams upon reflection and results in mode mismatches in coupled cavities that need to be mitigated. Astigmatic thermal actuation for the optics involved is thus essential. One way we are considering is to implement a FROSTI-like barrel RH that delivers different irradiance for the four quadrants. This post summarizes primitive results on the astigmatic thermal actuation for the HR surface by powering the heater elements from one diagonal differently compared to the other.

For this study, we looked at a simple case with an aLIGO-like test mass geometry (R=0.17m, H=0.2m) plus a barrel RH with 0.02m width at 0.03m from the AR surface with FEniCSx. The irradiance profiles are constant inside the width along the longitudinal direction, and zero outside the width. For the baseline non-astigmatic actuation with constant irradiance azimuthally. We have obtained roughly equal quadratic actuations along the x and y directions, as shown in figure. The total delivered power on the entire barrel is normalized to 1 W. The actuation on the curvature per power Delta S/Delta P in this non-astigmatic case thus is 0.835 uD/W.

For the astigmatic case however, the irradiance for the regions from one diagonal is increased by a given amount, compared to the non-astigmatic case, whereas for the other diagonal regions is decreased by the same amount (thus the total power is unchanged at 1 W). The HR deformation when the power is changed by 50%, for instance, is shown in picture, where the deformation along the x direction is larger than the y direction. The deformation in each direction however remains quadratic, with different curvature per powers for the x and y components, as shown in plot. The actuation on the curvature per power for an increasing amount of astigmatism is shown in plot. In terms of Zernike polynomials, the maximum amount of Z22 (astigmatism) for 1 W of total power is 2um while the remaining curvature content (Z20) is 6nm. This is shown in plot.

  394   Fri Jul 5 14:12:32 2024 LiuUpdateInterferometer SimulationsCE BS Mechanical Resonances
The butterfly and drumhead mechanical modes for the aLIGO BS were calculated in COMSOL. The resonant frequencies for the two acoustic modes are 2.45 kHz and 3.61 kHz, matching the results in reference for instance.

For a quick projection for the resonant frequencies going from aLIGO to CE, the height and width of the BS are increased assuming the mass is increased from 14 kg to 70 kg, while keeping the aspect ratio fixed. The resonant frequencies for the two mechanical modes as a result becomes smaller, to 1.43 kHz and 2.11 kHz respectively, risking getting in the detection band.

Next step is to implement a mechanical ring with high stiffness outside the BS barrel to combat the decrement of the resonant frequencies of the relevant mechanical modes.

  395   Fri Jul 5 14:23:13 2024 LiuUpdateInterferometer SimulationsEngineering drawings for straight edge heater element designs for FROSTI
Step files and engineering drawings for the straight edge heater element designs have been created in COMSOL and SolidWorks. They are available in the group Git Repo. With those, we will initiate a discussion with the ceramics supplier for an estimate of the feasibility and benefits of the straight edge element over the curved element in terms of manufacturing cost and time.
  397   Mon Jul 8 12:26:10 2024 MichaelUpdateInterferometer SimulationsMinimizing Astigmatic Effects in the SRC of LIGO
This is the first look and analysis of the effects of astigmatism in the aLIGO optical layout which can lead to mode mismatch and therefore increased losses into higher order modes. Specifically I am currently looking at measuring the effect of changing the radii of curvature of the SRC mirrors https://docs.google.com/presentation/d/1qhIehqyNukg4g8S2fqfQZz83yr9aB76tEa6fn2J-TrM/edit?usp=sharing
  404   Mon Jul 15 09:36:44 2024 LiuUpdateInterferometer SimulationsETM Profile Optimization for FROSTI

This is to optimize the FROSTI heating profile for ETM, by minimizing the residual RMSE of the HR surface deformation after the beam size weighted curvature is removed by the current RH. The parameters of the profile being explored are the location, width, and total power for the Gaussian Annulus. As shown in the attached series of plots, the optimal location is 9.9 cm, with a width of 7.7 cm, and a total FROSTI power of 12.7 W (for 1 W of Gaussian beam absorption). The residual RMSE is 1.2 nm. About 0.5% of the FROSTI power is lost at the edges of the TM.

For comparison, without FROSTI, the residual RMSE after the beam size weighted curvature removed by the current RH is 44.5 nm. When the width of the Annulus is set to be 3 cm however, the residual RMS is 3.1 nm, with much smaller FROSTI power needed at 4.7 W, and less power loss at 0.02%.

  406   Mon Jul 15 14:28:32 2024 PooyanUpdateInterferometer SimulationsaLIGO test mass surface profiles

Created a Google Slides presentation to summarize all the mirror surface map information that we use for simulating interferometers. 

A+ expected maps are based on correspondence with G. Billingsley. The estimate for the A+ ITMs will be to take the “as polished” data and add coating non-uniformity to it. (T2000398) Neither of these are scaled for the precise thickness of the Ti:Ge coatings.

Google Slides link: https://docs.google.com/presentation/d/1ge-ciAiEdNyyTvSShYdZz2JpACFRY2W3JDpxHRqMnOQ/edit?usp=sharing

 

 

 

  408   Mon Jul 15 15:44:52 2024 Cynthia UpdateInterferometer Simulationsperformed cavity scans with thermal effects and ring heater
  409   Mon Jul 15 15:52:40 2024 MichaelUpdateInterferometer SimulationsaLIGO locking with varying SRC mirrors and measuring mode mismatch
  413   Mon Jul 29 12:18:52 2024 LiuUpdateInterferometer SimulationsUpdate on FROSTI O5 ETM profile optimization
Update on FROSTI O5 ETM profile optimization is attached.
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