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fresnel

fresnel#

Functions for probe initialization using a model of Fresnel optics.

tike.ptycho.fresnel.MW_probe(probe_shape, lambda0, dx, dis_defocus, zone_plate_params, energy=1, bandwidth=0.01, spectrum=None)[source]#

Estimate multi-energy probes using Fresnel propagation model of optics.

Example

MW_probe(
    probe_shape=64
    lambda0=1.24e-9 / 10
    dx=6e-6
    dis_defocus=800e-6
    dis_StoD=2
    zone_plate_params=dict(
        radius=150e-6 / 2,
        outmost=50e-9,
        beamstop=60e-6,
    ),
    energy=5,
    bandwidth=0.01,
)
Parameters

  • probe_shape (int) – The pixel width and height of the (square) probe illumination.

  • lambda0 (float [m]) – The central wavelength of the illumination.

  • dx (float [m]) – The pixel size on sample plane

  • dis_defocus (float [m]) – The defocus distance; the distance from the sample to the focal plane. May be negative.

  • zone_plate_params (str or dict) – One of ‘velo’, ‘2idd’, ‘lamni’ or a dictionary with the following keys: radius: float [m] zone plate radius, outmost : float [m] outmost zone width, and beamstop : float [m] diameter of central beamstop.

  • energy (int) – number of energies for multi-wavelength method

  • spectrum ([(wavelength, intensity), (wavelength, intensity), ...]) – A 2-tuple of wavelength and intensity for each energy. Assumes spectrum provided in ascending order by wavelength.

  • bandwidth (float [m]) – The full width at half maximum of the spectrum divided by the central wavelength.

Returns

probe – An estimate of the probes sorted by spectrum.

Return type

(1, 1, SHARED, WIDE, HIGH) complex64

tike.ptycho.fresnel.single_probe(probe_shape, lambda0, dx, dis_defocus, zone_plate_params)[source]#

Estimate the probe using Fresnel propagation model of focusing optics.

Example

single_probe(
    probe_shape=64
    lambda0=1.24e-9 / 10
    dx=6e-6,
    dis_defocus=800e-6
    zone_plate_params=dict(
        radius=150e-6 / 2,
        outmost=50e-9,
        beamstop=60e-6,
    ),
)
Parameters

  • probe_shape (int) – The pixel width and height of the (square) probe illumination.

  • lambda0 (float [m]) – The central wavelength of the illumination.

  • dx (float [m]) – The pixel size on sample plane

  • dis_defocus (float [m]) – The defocus distance; the distance from the sample to the focal plane. May be negative.

  • dis_StoD (float [m]) – The sample to detector distance.

  • zone_plate_params (str or dict) – One of ‘velo’, ‘2idd’, ‘lamni’ or a dictionary with the following keys: radius: float [m] zone plate radius, outmost : float [m] outmost zone width, and beamstop : float [m] diameter of central beamstop.

Returns

probe – An estimate of the probe.

Return type

(1, 1, SHARED, WIDE, HIGH) complex64

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