odak.wave.transfer_function_fresnel¶

A definition to calculate convolution based Fresnel approximation for beam propagation.

Parameters:

Name	Type	Description	Default
`field`	`np.complex`	Complex field (MxN).	required
`k`	`odak.wave.wavenumber`	Wave number of a wave, see odak.wave.wavenumber for more.	required
`distance`	`float`	Propagation distance.	required
`dx`	`float`	Size of one single pixel in the field grid (in meters).	required
`wavelength`	`float`	Wavelength of the electric field.	required

Returns:

Type	Description
`np.complex`	Final complex field (MxN).

Source code in odak/wave/classical.py

def transfer_function_fresnel(field, k, distance, dx, wavelength):
    """
    A definition to calculate convolution based Fresnel approximation for beam propagation.

    Parameters
    ----------
    field            : np.complex
                       Complex field (MxN).
    k                : odak.wave.wavenumber
                       Wave number of a wave, see odak.wave.wavenumber for more.
    distance         : float
                       Propagation distance.
    dx               : float
                       Size of one single pixel in the field grid (in meters).
    wavelength       : float
                       Wavelength of the electric field.

    Returns
    -------
    result           : np.complex
                       Final complex field (MxN).

    """
    nv, nu = field.shape
    fx = np.linspace(-1./2./dx, 1./2./dx, nu)
    fy = np.linspace(-1./2./dx, 1./2./dx, nv)
    FX, FY = np.meshgrid(fx, fy)
    H = np.exp(1j*k*distance*(1-(FX*wavelength)**2-(FY*wavelength)**2)**0.5)
    U1 = np.fft.fftshift(np.fft.fft2(np.fft.fftshift(field)))
    U2 = H*U1
    result = np.fft.ifftshift(np.fft.ifft2(np.fft.ifftshift(U2)))
    return result

odak.wave.transfer_function_fresnel¶

See also¶