{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Interferometer\n\nA double slit interferometer with a point source. Multiprocess propagation is \nused to obtain the interferogram produced by different configurations of the \noptical system.\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Import libraries required for simulation\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "from copy import deepcopy\n\nimport matplotlib.pyplot as plt\nimport numpy as np\n\nimport pysrw as srw"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Create the wavefront arriving at the first plane of the optical system with \nparameters similar to :doc:`simple_propagation`\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "ptSrc = srw.emitters.PointSource()\n\nobserver = srw.wavefronts.Observer(centerCoord=[0, 0, .5],\n                                   obsXextension=5e-3, \n                                   obsYextension=5e-3,\n                                   obsXres=1e-6,\n                                   obsYres=1e-6)\n\nwfr = srw.computePtSrcWfr(ptSrc, observer, wavelength=600)\n\nw = 500e-6\nd = 2e-3\nf = 50e-3\ns1 = observer.zPos\ns2 = s1 * f / (s1 - f)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We use a rectangular aperture with an obstacle at the centre to create the \ntwo interferometer slits\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "optSystem = {\n    \"slitAp\": {\n        \"type\": \"rectAp\",\n        \"extension\": [w, d + w],\n        \"centre\": [0,0]\n    },\n    \"slitOb\": {\n        \"type\": \"rectOb\",\n        \"extension\": [2 * w, d - w],\n        \"centre\": [0,0]\n    },\n    \"lens\": {\n        \"type\": \"lens\",\n        \"f\": f,\n        \"centre\": [0,0]\n    },\n    \"image\": {\n        \"type\": \"drift\",\n        \"length\": s2,\n        \"resParam\": {\"hRangeChange\": 1/20, \"hResChange\": 2.0,\n                     \"vRangeChange\": 1/20, \"vResChange\": 2.0,\n                     \"hCentreChange\": 0.0, \"vCentreChange\": 0.0}\n    }\n}"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We proceed with a standard propagation to check that the parameters are good.\nAs expected, the interferogram of the point emitter exhibits a unitary \nvisibility and its envelope lies within the single slit diffraction pattern.\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "propData = srw.propagateWfr(wfr, optSystem, saveIntAt=[\"image\"])\nsrw.plotI(propData[\"image\"][\"intensity\"])\n\ncuts = srw.extractCrossCuts(propData[\"image\"][\"intensity\"])\nyax = cuts[\"yax\"]\nint_srw = cuts[\"ydata\"]\nint_theo = np.sinc(w * yax / (s2 * wfr.wavelength*1e-9))**2\n\nfig, ax = plt.subplots()\nax.plot(yax*1e3, int_srw / np.max(int_srw))\nax.plot(yax*1e3, int_theo, label=\"theo\", linestyle=\"--\")\nax.set_xlabel(\"y position [mm]\")\nax.set_ylabel(\"Intensity [arb. unit]\")\nax.legend()\nplt.tight_layout()\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We can finally create a list of optical systems by changing the slit \nseparation and observe the corresponding change in the fringe periodicity.\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "deltas = np.linspace(-.5, .5, 3) * 1e-3\n\noptSystems = []\nfor delta in deltas:\n    optSystemNew = deepcopy(optSystem)\n    optSystemNew[\"slitAp\"][\"extension\"][1] += delta\n    optSystemNew[\"slitOb\"][\"extension\"][1] += delta\n\n    optSystems.append(optSystemNew)\n\npropDatas = srw.propagateWfrMultiProcess(4, wfr, optSystems, saveIntAt=[\"image\"])\n\nfig, ax = plt.subplots()\nfor i, propData in enumerate(propDatas):\n    cuts = srw.extractCrossCuts(propData[\"image\"][\"intensity\"])\n    yax = cuts[\"yax\"]\n    int_srw = cuts[\"ydata\"]\n    ax.plot(yax*1e3, int_srw / np.max(int_srw), label=f\"{(d + deltas[i])*1e3}\")\nax.set_xlabel(\"y position [mm]\")\nax.set_ylabel(\"Intensity [arb. unit]\")\nax.legend(title=\"Separation [mm]\")\nplt.tight_layout()\nplt.show()"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
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    "language_info": {
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      "file_extension": ".py",
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