finesse-virgo

Finesse 3.0 Virgo models, tools, and data. This package is an optional extra to the finesse package which must be installed to use this package.

Quick Plots

These plots have been generated using the current configuration of the model (see scripts/build_plots.py).

Installation

From PyPI

If you just want to use the tools and models provided you can use pip install finesse-virgo to install the latest tagged commit.

From Source

If you want to have the latest changes you can instead install from source:

git clone https://gitlab.com/ifosim/finesse/finesse-virgo.git
cd finesse-virgo
pip install -e .

Periodically running git pull will then retrieve any changes.

Documentation

Documentation explaining the parameters used in the model can be found at https://finesse.ifosim.org/docs/finesse-virgo/latest/ (HTML) and https://finesse.ifosim.org/docs/finesse-virgo/pdf/latest/ (PDF).

Alternatively, the documentation can be built from the source, found at https://git.ligo.org/finesse/finesse-virgo-docs/ .

Usage

This package includes top-level tools and models for simulating Virgo in Finesse 3. Individual simulations that you perform should be stored elsewhere, such as the finesse_playground repository. Your scripts should just import this package.

The Virgo pre-tuning tool can be used to create an AdV+ model and pre-tune it to an operating point.

Start by creating a Virgo model:

# create a new Virgo model
virgo = finesse.virgo.Virgo()

This will create a Virgo model using the current state of the common file.

Alternatively, an existing configuration can be provided as a starting point:

# create a Virgo model using a custom input file
virgo = finesse.virgo.Virgo('custom_file.kat')

This will parse the necessary files into a Finesse 3 model and prepare the model for tuning. See examples/creating_virgo.ipynb for additional examples.

With the Virgo model created, we can then begin to step through the pre-tuning process:

# step 1: adjust the cavity lengths
virgo.adjust_PRC_length()
virgo.adjust_SRC_length()

# step 2: pretune
virgo.pretune()

# step 3: optimize demodulation phases
virgo.optimize_demodulation_phase()

# step 4: optimize lock gains
virgo.optimize_lock_gains()

# step 5: run RF locks
virgo.model.run(RunLocks(method="newton"))

# step 6: switch DARM to DC lock with an offset
virgo.model.run(DARM_RF_to_DC())

Alternatively, the previous steps can be combined by simply using make():

# completes all steps at once
virgo.make()

See examples/general_usage.ipynb for additional examples.

Printing

Various printing functions are available to display information about the current state of the model.

For example, it may be useful to display important lengths and frequencies:

# display lengths and
virgo.print_lengths()

┌─────────────────────────────────────────────────┐
│- Arm lengths [m]:                               │
│  LN   = 2999.8180   LW = 2999.7880              │
├─────────────────────────────────────────────────┤
│- Michelson and recycling lengths [m]:           │
│  ln   = 6.0152      lw       = 5.7851           │
│  lpr  = 6.0513      lsr      = 6.0509           │
│  lMI  = 5.9001      lSchnupp = 0.2301           │
│  lPRC = 11.9515     lSRC     = 11.9511          │
├─────────────────────────────────────────────────┤
│- Associated cavity frequencies [Hz]:            │
│  fsrN   = 49968.44    fsrW   = 49968.94         │
│  fsrPRC = 12542050.98 fsrSRC = 12542480.59      │
│                                                 │
│- Modulation sideband frequencies [MHz]:         │
│  f6     = 6.270777     f8     = 8.361036        │
│  f56     = 56.436993                            │
├─────────────────────────────────────────────────┤
│- Check frequency match [MHz]:                   │
│  125.5*fsrN-300 = 6.270739                      │
│  0.5*fsrPRC     = 6.271025                      │
│  0.5*fsrSRC     = 6.271240                      │
│  9*f6           = 56.436993                     │
└─────────────────────────────────────────────────┘

Or display the carrier power at key nodes throughout the interferometer:

# display carrier power at key nodes
virgo.print_powers()

┌────────────────────────────────────────┐
│ Detector         Power [W]  Pow. ratio │
├────────────────────────────────────────┤
│ CAR_AMP_PRin  :         40          1  │
│ CAR_AMP_N     :  2.482e+05       6205  │
│ CAR_AMP_W     :  2.454e+05       6134  │
│ CAR_AMP_BS    :       1748      43.69  │
│ CAR_AMP_AS    :     0.0182   0.000455  │
└────────────────────────────────────────┘

See examples/printing.ipynb for more printing examples.

Plotting

The quantum-noise limited sensitivity curve is a good way to determine if we are at an operating point:

virgo.plot_QNLS()

Similarly, the DARM transfer function can also be plotted:

virgo.plot_DARM()

See examples/plotting.ipynb for additional plotting examples.

Contributing

If you want to contribute any changes or code to this project then it must be done via a merge request. Merge requests must pass all tests before being merged.

The pipeline will fail if pre-commit has not been run. After cloning the git repository please run pip install pre-commit; pre-commit install. This will ensure that formatting and simple code errors are fixed using black and flake8.

Documentation for functions should be in the numpydoc format: https://numpydoc.readthedocs.io/en/latest/format.html

Adding new katscript

New KatScript elements and commands must be registered with the FINESSE parser. This is done in the top level __init__.py which registers each of the objects required.

Support

Please post an issue if you are experiencing any bugs, problems, or feature requests. https://chat.ligo.org/ligo/channels/finesse can also be used for broader discussion on Finesse and modelling Virgo with it.

License

All code here is distributed under GPL v3.

Packaging

The finesse-virgo is automatically uploaded to pypi when new tags are pushed to main. Tags must be annotated and be in the semantic versioning form MAJOR.MINOR.PATCH:

• MAJOR version when you make incompatible API changes,
• MINOR version when you add functionality in a backwards compatible manner, and
• PATCH version when you make backwards compatible bug fixes.

Only maintainers can push tags to the main branch.