Experimental Data¶
PtyLab.ExperimentalData
¶
ExperimentalData
¶
ExperimentalData
¶
Store experimental data and geometry for a PtyLab reconstruction.
The class defines the experimental fields required for conventional ptychography (CPM) or Fourier ptychography (FPM), loads them from an HDF5 dataset, and derives basic detector and acquisition quantities used by the reconstruction.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
filename
|
str or Path
|
Path to an experimental HDF5 dataset. If None, the object is initialized without loading a dataset. |
None
|
operationMode
|
str
|
Ptychographic operation mode, either conventional ptychography
( |
'CPM'
|
Attributes:
| Name | Type | Description |
|---|---|---|
operationMode |
str
|
Selected ptychographic operation mode. |
ptychogram |
ndarray
|
Stack of measured intensity images. Available after data have been loaded. |
wavelength |
float
|
Illumination wavelength in meters. |
encoder |
ndarray
|
Position or illumination-coordinate data associated with the measurements. |
dxd |
float
|
Detector pixel size in meters. |
Nd |
int
|
Number of detector pixels along one dimension. |
Ld |
float
|
Physical detector width in meters. |
numFrames |
int
|
Number of measured frames. |
zo |
float
|
Sample-to-detector distance in meters. Available for CPM datasets. |
zled |
float
|
LED-to-sample distance in meters. Available for FPM datasets. |
magnification |
float
|
Microscope magnification. Available for FPM datasets. |
Raises:
| Type | Description |
|---|---|
ValueError
|
If |
Notes
CPM and FPM require different acquisition parameters. For CPM, the
required fields include zo (sample-to-detector distance), whereas
FPM requires zled and magnification.
Geometric quantities are expected in SI units, with distances given in meters.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
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loadData(filename=None)
¶
Load a ptychography dataset and initialize the corresponding experimental data.
The dataset fields required for loading depend on the selected operation mode. Example-data aliases can be used instead of explicit file paths.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
filename
|
str or Path
|
Path to the dataset to load. The following special aliases are supported:
|
None
|
Notes
After loading, the dataset fields are added as attributes of the
ExperimentalData instance.
Derived quantities such as detector coordinates, detector size,
number of frames, and probe-power estimates are initialized by
_setData().
The ptychogram orientation is applied after loading according to the orientation metadata stored in the dataset.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
reduce_positions(start, end)
¶
Restrict the dataset to a contiguous subset of measurement positions.
The ptychogram and the corresponding encoder positions are sliced along their first dimension using standard Python slicing semantics.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
start
|
int
|
Index of the first measurement position to retain. |
required |
end
|
int
|
Index at which to stop the selection. The measurement at this index is not included. |
required |
Notes
This method modifies self.ptychogram and self.encoder in place.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
cropCenter(size)
¶
Crop each diffraction pattern to a centered square region.
The ptychogram is cropped along its two detector dimensions while the number of measurement frames is preserved.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
size
|
int
|
Number of detector pixels retained along each dimension of the cropped diffraction patterns. |
required |
Raises:
| Type | Description |
|---|---|
TypeError
|
If |
Notes
This method modifies self.ptychogram in place.
Derived detector quantities such as Nd and Ld are currently
not recomputed by this method.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
binData(binning)
¶
:param binning: Binning parameter (int, e.g. 2) :return:
Source code in PtyLab/ExperimentalData/ExperimentalData.py
setOrientation(orientation, force_contiguous=True)
¶
Sets the correct orientation. This function follows the ptypy convention.
If orientation is None, it won't change the current orientation.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
showPtychogram()
¶
show ptychogram.
Source code in PtyLab/ExperimentalData/ExperimentalData.py
relative_intensity(index)
¶
Return the relative intensity of the ptychogram at index compared to the brightest one
Parameters¶
index