"""
FresnelZoom1D — 1-D zoomed Fresnel propagator allowing an arbitrary output sampling window via chirp-z resampling.
"""
import numpy
from wofry.propagator.wavefront1D.generic_wavefront import GenericWavefront1D
from wofry.propagator.propagator import Propagator1D
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class FresnelZoom1D(Propagator1D):
HANDLER_NAME = "FRESNEL_ZOOM_1D"
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def get_handler_name(self):
return self.HANDLER_NAME
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def do_specific_progation_after(self, wavefront, propagation_distance, parameters, element_index=None):
return self.do_specific_progation(wavefront, propagation_distance, parameters, element_index=element_index)
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def do_specific_progation_before(self, wavefront, propagation_distance, parameters, element_index=None):
return self.do_specific_progation( wavefront, propagation_distance, parameters, element_index=element_index)
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def do_specific_progation(self, wavefront1, propagation_distance, parameters, element_index=None):
magnification_x = self.get_additional_parameter("magnification_x",1.0,parameters,element_index=element_index)
return self.propagate_wavefront(wavefront1,propagation_distance,magnification_x=magnification_x)
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@classmethod
def propagate_wavefront(cls,wavefront1,propagation_distance,magnification_x=1.0):
wavefront = wavefront1.duplicate()
shape = wavefront.size()
delta = wavefront.delta()
wavenumber = wavefront.get_wavenumber()
wavelength = wavefront.get_wavelength()
fft_scale = numpy.fft.fftfreq(shape)/delta
x = wavefront.get_abscissas()
x_rescaling = wavefront.get_abscissas() * magnification_x
r1sq = x ** 2 * (1 - magnification_x)
r2sq = x_rescaling ** 2 * ((magnification_x - 1) / magnification_x)
fsq = (fft_scale ** 2 / magnification_x)
Q1 = wavenumber / 2 / propagation_distance * r1sq
Q2 = numpy.exp(-1.0j * numpy.pi * wavelength * propagation_distance * fsq)
Q3 = numpy.exp(1.0j * wavenumber / 2 / propagation_distance * r2sq)
wavefront.add_phase_shift(Q1)
fft = numpy.fft.fft(wavefront.get_complex_amplitude())
ifft = numpy.fft.ifft(fft * Q2) * Q3 / numpy.sqrt(magnification_x)
wf_propagated = GenericWavefront1D.initialize_wavefront_from_arrays(x_rescaling,
ifft,
wavelength=wavelength)
return wf_propagated