Stefan Hild(University of Birmingham)

+ A.Freise, M.Mantovani, A.Perreca

Advanced Virgo telecon, June 2008

Why use FinesseTools for Advanced Virgo simulations, a simple example.

S. Hild Advanced Virgo, 19th of June 2008 Slide 2

Outline

Motivation: Why to use FinesseTools for OSD-work?

Infrastructure for OSD-Simulations Advanced Virgo OSD_Tools SVN

Example of an OSD_Tool_function Calculating the mirror ROCs for a given beam size

Current baseline of ROCs for main and recycling mirrors

S. Hild Advanced Virgo, 19th of June 2008 Slide 3

Introduction: Why to use FinesseTools for OSD simulation work

We need to do plenty of simulations for Advanced Virgo Many of these simulation task are fairly big constructs (for instance

producing control matrix)

Many parameters are not fixed and might change several times within the next year or so For instance: mod frequencies, Schnupp asymmetry, ...

Many design options are available which might completely change everything For instance degenerate recycling cavities

We will have to do the simulations many times, with several parameter set, several optimization criteria …

S. Hild Advanced Virgo, 19th of June 2008 Slide 4

Introduction: Why to use FinesseTools for OSD simulation work

IDEA: Build up a collection of (semi) automated scripts and functions, called OSD_Tools For instance for: Calculating the mirror ROCs for a given beam size Calculating the optimal Schnupp length for given modulation frequencies Calculating the length of the SR-cavity for given Schnupp length and modulation

frequency Calculating an optimized Control matrix for a given IFO configuration

These scripts and functions always read in the current Advanced Virgo parameter set (from Finesse baseline file) and give back an optimized parameter set.

Example scenario: Suppose the length of one recycling cavity changes Need to redo the full length control scheme (including all noise

propagations). OSD_Tools can make things easier, more reliable and better

documented.

S. Hild Advanced Virgo, 19th of June 2008 Slide 5

Infrastructure: OSD-SVN

A dedicated SVN for OSD Simulation effort

All scripts and input files are stored in a subversion repository including backup and version control.

This svn can be read by the public: Server: svn://lnx0.sr.bham.ac.uk Repository: adv-osd

Everybody is welcome to join …

S. Hild Advanced Virgo, 19th of June 2008 Slide 6

Infrastructure: OSD-SVN

Four main directories

Finesse-files: Current and Previous input

files (Parameter documentation)

OSD-tools: Top Level OSD-function

FinesseTools

Tasks: Example scripts how to run

the Top Level OSD-functions

S. Hild Advanced Virgo, 19th of June 2008 Slide 7

Example: Determine the mirror ROCs for a given beam size

The value for the Advanced Virgo beam size is likely to change in future: There is a current baseline value (6.0cm) New info about …

Size of flats Geometry and type of actuators FFT simulations… will make it necessary to modify the beam size

The lengths of the recycling cavities is not fixed: For each length the recycling mirrors need to have a an adjusted

curvature

Every time the beam size or the cavity lengths changes we have to recalculated all the curvatures of the mirrors.

It would be nice doing these calculations always by just pressing a single button (I.e. running a single function.)

S. Hild Advanced Virgo, 19th of June 2008 Slide 8

OSD_ROC.m: What does it do?1. Reads in the current an Advanced Virgo configuration from the current

Advanced Virgo Finesse file (advirgo-base-xxxxxx.kat)

2. Switches off all cavity commands and use the pure eigenmode of the arm cavities.

3. Produce and run new Finesse simulation: beam size over main mirror ROC

4. Find main mirror ROC value corresponding to the wished beam size

5. Repeat step 3. and 4. with higher resolution (2nd iteration)

6. Write the new ROC value to the main mirrors.

7. Produce and run new Finesse simulation: beam parameter detector at the recycling mirrors

8. Calculates from z and z_r values the wavefront curvature of the recycling mirrors.

9. Writes a new Advanced Virgo input file, containing the new ROC values. (This file can then be used by the next OSD-Tool-function…)

S. Hild Advanced Virgo, 19th of June 2008 Slide 9

OSD_ROC.m: What does it do?

For further detail, please look at the help of the function:

S. Hild Advanced Virgo, 19th of June 2008 Slide 10

Current baseline for beam size and mirror curvatures

S. Hild Advanced Virgo, 19th of June 2008 Slide 11

Documentation on the Wiki

Available on the AdV-OSD-Wiki:

Very brief summary of beamsize analysis

Current working values for mirror curvatures

https://workarea.ego-gw.it/ego2/virgo/advanced-virgo/osd/beam-sizes

S. Hild Advanced Virgo, 19th of June 2008 Slide 12

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