pois 0.4.0

Python optical interferometer simulation

A python package providing the building blocks to simulate the operation of a ground-based optical interferometer perturbed by atmospheric seeing perturbations. It is provided as supplementary material for the book “Practical Optical Interferometry”, and is derived from the code which was used to provide data for many of the figures in the book.

The package includes functions to:

• generate simulated atmospheric turbulent wavefront perturbations

• correct these perturbations using adaptive optics

• combine beams from an arbitrary number of telescopes, with or without spatial filtering, to provide complex fringe visibility measurements.

The code has been written following a functional-programming style (in other words minimising “side-effects” in the code where possible) in order to try and make it modular and extensible.

Requirements

The simulator runs under Python3 and requires numpy. Some of the test code uses astropy for manipulating and saving data tables.

Installation

On unix-like systems do

pip3 install pois

or if that does not work because of file permission errors, then

sudo pip3 install pois

Alternatively download and unpack a copy of this repository and then use

python3 setup.py install

This should install the package into Python path.

Basic usage

An interferometric simulation can be written as a for loop with some custom data processing, for example:

from pois import *

results=[]
for phaseScreens in PhaseScreens(numTelescope=3,
                                 r0=15,
                                 pupilSize=30,
                                 screenSize=1024,
                                 numIter=1000)):
    pupils=AdaptiveOpticsCorrect(phaseScreens,pupilSize=30,radialOrder=5)
    complexPupils=ComplexPupil(pupils)
    fluxes,coherentFluxes=SingleModeCombine(complexPupils)
    # process() is a user-written data processing function
    results.append(process(fluxes,coherentFluxes))

More example code using the package is in the tests directory. The file tests/test_visibility.py includes a complete simulation for determining visibility losses and single-mode fibre coupling losses as a function of the diameter of the telescopes.

Pronunciation

The package name should be pronounced as it would be in the phrase “petits pois”.

Licencing

The code is licenced under a 2-clause BSD licence (see LICENCE.txt).