Skip to content

Propagators

MFT

Bases: Propagator

Propagates a Wavefront using the MFT algorithm, allowing for the pixel_scale and number of pixels to be specified in the output plane.

UML

UML

Attributes:

Name Type Description
npixels int

The number of pixels in the output plane.

pixel_scale (float, meters / pixel or radians / pixel)

The pixel scale in the output plane. Has units of radians/pixel if focal_length is None, else meters/pixel.

focal_length (float, meters)

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

Source code in src/dLux/layers/propagators.py
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
class MFT(Propagator):
    """
    Propagates a `Wavefront` using the MFT algorithm, allowing for the pixel_scale and
    number of pixels to be specified in the output plane.

    ??? abstract "UML"
        ![UML](../../assets/uml/MFT.png)

    Attributes
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/pixel or radians/pixel
        The pixel scale in the output plane. Has units of radians/pixel if focal_length
        is None, else meters/pixel.
    focal_length : float, meters
        The focal_length of the lens/mirror this propagator represents. If None, the
        output pixel_scale has units radians/pixel, else meters/pixels.
    """

    npixels: int
    pixel_scale: float

    def __init__(
        self: Propagator,
        npixels: int,
        pixel_scale: float,
        focal_length: float = None,
    ):
        """
        Parameters
        ----------
        npixels : int
            The number of pixels in the output plane.
        pixel_scale : float, meters/pixel or radians/pixel
            The pixel scale in the output plane. Has units of radians/pixel if
            focal_length is None, else meters/pixel.
        focal_length : float = None, meters
            The focal_length of the lens/mirror this propagator represents. If None,
            the output pixel_scale has units radians/pixel, else meters/pixels.
        """
        super().__init__(focal_length=focal_length)

        self.pixel_scale = float(pixel_scale)
        self.npixels = int(npixels)

    def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
        """
        Applies the layer to the wavefront.

        Parameters
        ----------
        wavefront : Wavefront
            The wavefront to operate on.

        Returns
        -------
        wavefront : Wavefront
            The transformed wavefront.
        """
        return wavefront.propagate(
            self.npixels,
            self.pixel_scale,
            self.focal_length,
        )

__init__(npixels, pixel_scale, focal_length=None)

Parameters:

Name Type Description Default
npixels int

The number of pixels in the output plane.

required
pixel_scale (float, meters / pixel or radians / pixel)

The pixel scale in the output plane. Has units of radians/pixel if focal_length is None, else meters/pixel.

required
focal_length float = None, meters

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

None
Source code in src/dLux/layers/propagators.py
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
def __init__(
    self: Propagator,
    npixels: int,
    pixel_scale: float,
    focal_length: float = None,
):
    """
    Parameters
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/pixel or radians/pixel
        The pixel scale in the output plane. Has units of radians/pixel if
        focal_length is None, else meters/pixel.
    focal_length : float = None, meters
        The focal_length of the lens/mirror this propagator represents. If None,
        the output pixel_scale has units radians/pixel, else meters/pixels.
    """
    super().__init__(focal_length=focal_length)

    self.pixel_scale = float(pixel_scale)
    self.npixels = int(npixels)

apply(wavefront)

Applies the layer to the wavefront.

Parameters:

Name Type Description Default
wavefront Wavefront

The wavefront to operate on.

required

Returns:

Name Type Description
wavefront Wavefront

The transformed wavefront.

Source code in src/dLux/layers/propagators.py
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
    """
    Applies the layer to the wavefront.

    Parameters
    ----------
    wavefront : Wavefront
        The wavefront to operate on.

    Returns
    -------
    wavefront : Wavefront
        The transformed wavefront.
    """
    return wavefront.propagate(
        self.npixels,
        self.pixel_scale,
        self.focal_length,
    )
FFT

Bases: Propagator

Propagates a Wavefront using the FFT algorithm.

UML

UML

TODO: Update padding to take in units of npixels, rather than factor.

Attributes:

Name Type Description
focal_length float

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

pad int

The zero-padding factor to apply to the Wavefront before propagation. In general, this should be greater than 2 to avoid aliasing.

Source code in src/dLux/layers/propagators.py
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
class FFT(Propagator):
    """
    Propagates a `Wavefront` using the FFT algorithm.

    ??? abstract "UML"
        ![UML](../../assets/uml/FFT.png)

    # TODO: Update padding to take in units of npixels, rather than factor.

    Attributes
    ----------
    focal_length : float
        The focal_length of the lens/mirror this propagator represents. If None, the
        output pixel_scale has units radians/pixel, else meters/pixels.
    pad : int
        The zero-padding factor to apply to the `Wavefront` before propagation. In
        general, this should be greater than 2 to avoid aliasing.
    """

    pad: int

    def __init__(self: Propagator, focal_length: float = None, pad: int = 2):
        """
        Parameters
        ----------
        focal_length : float = None
            The focal_length of the lens/mirror this propagator represents. If None, the
            output pixel_scale has units radians/pixel, else meters/pixels.
        pad : int = 2
            The zero-padding factor to apply to the `Wavefront` before propagation. In
            general, this should be greater than 2 to avoid aliasing.
        """
        super().__init__(focal_length=focal_length)
        self.pad = int(pad)

    def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
        """
        Applies the layer to the wavefront.

        Parameters
        ----------
        wavefront : Wavefront
            The wavefront to operate on.

        Returns
        -------
        wavefront : Wavefront
            The transformed wavefront.
        """
        return wavefront.propagate_FFT(self.focal_length, self.pad)

__init__(focal_length=None, pad=2)

Parameters:

Name Type Description Default
focal_length float = None

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

None
pad int = 2

The zero-padding factor to apply to the Wavefront before propagation. In general, this should be greater than 2 to avoid aliasing.

2
Source code in src/dLux/layers/propagators.py
65
66
67
68
69
70
71
72
73
74
75
76
77
def __init__(self: Propagator, focal_length: float = None, pad: int = 2):
    """
    Parameters
    ----------
    focal_length : float = None
        The focal_length of the lens/mirror this propagator represents. If None, the
        output pixel_scale has units radians/pixel, else meters/pixels.
    pad : int = 2
        The zero-padding factor to apply to the `Wavefront` before propagation. In
        general, this should be greater than 2 to avoid aliasing.
    """
    super().__init__(focal_length=focal_length)
    self.pad = int(pad)

apply(wavefront)

Applies the layer to the wavefront.

Parameters:

Name Type Description Default
wavefront Wavefront

The wavefront to operate on.

required

Returns:

Name Type Description
wavefront Wavefront

The transformed wavefront.

Source code in src/dLux/layers/propagators.py
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
    """
    Applies the layer to the wavefront.

    Parameters
    ----------
    wavefront : Wavefront
        The wavefront to operate on.

    Returns
    -------
    wavefront : Wavefront
        The transformed wavefront.
    """
    return wavefront.propagate_FFT(self.focal_length, self.pad)
ShiftedMFT

Bases: MFT

Propagates a Wavefront using the MFT algorithm, allowing for the pixel_scale and number of pixels to be specified in the output plane. Also optionally allows for a shift to be applied to the wavefront in the output plane.

UML

UML

Attributes:

Name Type Description
npixels int

The number of pixels in the output plane.

pixel_scale (float, meters / pixel or radians / pixel)

The pixel scale in the output plane. Has units of radians/pixel if focal_length is None, else meters/pixel.

focal_length (float, meters)

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

shift Array

The (x, y) shift to apply to the wavefront in the output plane.

pixel bool

If True the shift value is assumed to be in units of pixels, else the physical units of the output plane (ie radians if focal_length is None, else meters).

Source code in src/dLux/layers/propagators.py
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
class ShiftedMFT(MFT):
    """
    Propagates a `Wavefront` using the MFT algorithm, allowing for the pixel_scale and
    number of pixels to be specified in the output plane. Also optionally allows for a
    shift to be applied to the wavefront in the output plane.

    ??? abstract "UML"
        ![UML](../../assets/uml/ShiftedMFT.png)

    Attributes
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/pixel or radians/pixel
        The pixel scale in the output plane. Has units of radians/pixel if focal_length
        is None, else meters/pixel.
    focal_length : float, meters
        The focal_length of the lens/mirror this propagator represents. If None, the
        output pixel_scale has units radians/pixel, else meters/pixels.
    shift : Array
        The (x, y) shift to apply to the wavefront in the output plane.
    pixel : bool
        If True the shift value is assumed to be in units of pixels, else the physical
        units of the output plane (ie radians if focal_length is None, else meters).
    """

    shift: Array
    pixel: bool

    def __init__(
        self: Propagator,
        npixels: int,
        pixel_scale: float,
        shift: Array,
        focal_length: float = None,
        pixel: bool = False,
    ):
        """
        Parameters
        ----------
        npixels : int
            The number of pixels in the output plane.
        pixel_scale : float, meters/pixel or radians/pixel
            The pixel scale in the output plane. Has units of radians/pixel if
            focal_length is None, else meters/pixel.
        shift : Array
            The (x, y) shift to apply to the wavefront in the output plane.
        focal_length : float = None, meters
            The focal_length of the lens/mirror this propagator represents. If None,
            the output pixel_scale has units radians/pixel, else meters/pixels.
        pixel : bool = False
            If True the shift value is assumed to be in units of pixels, else the
            physical units of the output plane (ie radians if focal_length is None,
            else meters).
        """
        super().__init__(
            pixel_scale=pixel_scale,
            npixels=npixels,
            focal_length=focal_length,
        )

        self.shift = np.asarray(shift, float)
        self.pixel = bool(pixel)

        if self.shift.shape != (2,):
            raise ValueError(
                f"Shift must be a 2D array, got {self.shift.shape}."
            )

    def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
        """
        Applies the layer to the wavefront.

        Parameters
        ----------
        wavefront : Wavefront
            The wavefront to operate on.

        Returns
        -------
        wavefront : Wavefront
            The transformed wavefront.
        """
        return wavefront.propagate(
            self.npixels,
            self.pixel_scale,
            self.focal_length,
            self.shift,
            self.pixel,
        )

__init__(npixels, pixel_scale, shift, focal_length=None, pixel=False)

Parameters:

Name Type Description Default
npixels int

The number of pixels in the output plane.

required
pixel_scale (float, meters / pixel or radians / pixel)

The pixel scale in the output plane. Has units of radians/pixel if focal_length is None, else meters/pixel.

required
shift Array

The (x, y) shift to apply to the wavefront in the output plane.

required
focal_length float = None, meters

The focal_length of the lens/mirror this propagator represents. If None, the output pixel_scale has units radians/pixel, else meters/pixels.

None
pixel bool = False

If True the shift value is assumed to be in units of pixels, else the physical units of the output plane (ie radians if focal_length is None, else meters).

False
Source code in src/dLux/layers/propagators.py
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
def __init__(
    self: Propagator,
    npixels: int,
    pixel_scale: float,
    shift: Array,
    focal_length: float = None,
    pixel: bool = False,
):
    """
    Parameters
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/pixel or radians/pixel
        The pixel scale in the output plane. Has units of radians/pixel if
        focal_length is None, else meters/pixel.
    shift : Array
        The (x, y) shift to apply to the wavefront in the output plane.
    focal_length : float = None, meters
        The focal_length of the lens/mirror this propagator represents. If None,
        the output pixel_scale has units radians/pixel, else meters/pixels.
    pixel : bool = False
        If True the shift value is assumed to be in units of pixels, else the
        physical units of the output plane (ie radians if focal_length is None,
        else meters).
    """
    super().__init__(
        pixel_scale=pixel_scale,
        npixels=npixels,
        focal_length=focal_length,
    )

    self.shift = np.asarray(shift, float)
    self.pixel = bool(pixel)

    if self.shift.shape != (2,):
        raise ValueError(
            f"Shift must be a 2D array, got {self.shift.shape}."
        )

apply(wavefront)

Applies the layer to the wavefront.

Parameters:

Name Type Description Default
wavefront Wavefront

The wavefront to operate on.

required

Returns:

Name Type Description
wavefront Wavefront

The transformed wavefront.

Source code in src/dLux/layers/propagators.py
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
    """
    Applies the layer to the wavefront.

    Parameters
    ----------
    wavefront : Wavefront
        The wavefront to operate on.

    Returns
    -------
    wavefront : Wavefront
        The transformed wavefront.
    """
    return wavefront.propagate(
        self.npixels,
        self.pixel_scale,
        self.focal_length,
        self.shift,
        self.pixel,
    )
FarFieldFresnel

Bases: ShiftedMFT

Propagates a Wavefront using the MFT algorithm, modified to allows for more accurate representations of wavefront behaviour in the far-field regime, a few wavelengths away from focus in either direction. Allows for the pixel_scale and number of pixels to be specified in the output plane, and optionally allows for a shift to be applied to the wavefront in the output plane.

UML

UML

Attributes:

Name Type Description
npixels int

The number of pixels in the output plane.

pixel_scale float, meters/

The pixel scale in the output plane.

focal_length (float, meters)

The focal_length of the lens/mirror this propagator represents.

shift Array

The (x, y) shift to apply to the wavefront in the output plane.

pixel bool

If True the shift value is assumed to be in units of pixels, else the physical units of the output plane.

focal_shift (float, meters)

The shift in the propagation distance of the wavefront from focus.

Source code in src/dLux/layers/propagators.py
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
class FarFieldFresnel(ShiftedMFT):
    """
    Propagates a `Wavefront` using the MFT algorithm, modified to allows for more
    accurate representations of wavefront behaviour in the far-field regime, a few
    wavelengths away from focus in either direction. Allows for the pixel_scale and
    number of pixels to be specified in the output plane, and optionally allows for a
    shift to be applied to the wavefront in the output plane.

    ??? abstract "UML"
        ![UML](../../assets/uml/FarFieldFresnel.png)

    Attributes
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/
        The pixel scale in the output plane.
    focal_length : float, meters
        The focal_length of the lens/mirror this propagator represents.
    shift : Array
        The (x, y) shift to apply to the wavefront in the output plane.
    pixel : bool
        If True the shift value is assumed to be in units of pixels, else the physical
        units of the output plane.
    focal_shift : float, meters
        The shift in the propagation distance of the wavefront from focus.
    """

    focal_shift: float

    def __init__(
        self: Propagator,
        npixels: int,
        pixel_scale: float,
        focal_length: float,
        focal_shift: float,
        shift: Array = np.zeros(2),
        pixel: bool = False,
    ):
        """
        Parameters
        ----------
        npixels : int
            The number of pixels in the output plane.
        pixel_scale : float, meters/
            The pixel scale in the output plane.
        focal_length : float, meters
            The focal_length of the lens/mirror this propagator represents.
        focal_shift : float, meters
            The shift in the propagation distance of the wavefront from focus.
        shift : Array = np.zeros(2)
            The (x, y) shift to apply to the wavefront in the output plane.
        pixel : bool = False
            If True the shift value is assumed to be in units of pixels, else the
            physical units of the output plane.
        """
        self.focal_shift = float(focal_shift)
        super().__init__(
            shift=shift,
            pixel=pixel,
            focal_length=focal_length,
            pixel_scale=pixel_scale,
            npixels=npixels,
        )

    def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
        """
        Applies the layer to the wavefront.

        Parameters
        ----------
        wavefront : Wavefront
            The wavefront to operate on.

        Returns
        -------
        wavefront : Wavefront
            The transformed wavefront.
        """
        return wavefront.propagate_fresnel(
            self.npixels,
            self.pixel_scale,
            self.focal_length,
            self.focal_shift,
            self.shift,
            self.pixel,
        )

__init__(npixels, pixel_scale, focal_length, focal_shift, shift=np.zeros(2), pixel=False)

Parameters:

Name Type Description Default
npixels int

The number of pixels in the output plane.

required
pixel_scale float, meters/

The pixel scale in the output plane.

required
focal_length (float, meters)

The focal_length of the lens/mirror this propagator represents.

required
focal_shift (float, meters)

The shift in the propagation distance of the wavefront from focus.

required
shift Array = np.zeros(2)

The (x, y) shift to apply to the wavefront in the output plane.

zeros(2)
pixel bool = False

If True the shift value is assumed to be in units of pixels, else the physical units of the output plane.

False
Source code in src/dLux/layers/propagators.py
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
def __init__(
    self: Propagator,
    npixels: int,
    pixel_scale: float,
    focal_length: float,
    focal_shift: float,
    shift: Array = np.zeros(2),
    pixel: bool = False,
):
    """
    Parameters
    ----------
    npixels : int
        The number of pixels in the output plane.
    pixel_scale : float, meters/
        The pixel scale in the output plane.
    focal_length : float, meters
        The focal_length of the lens/mirror this propagator represents.
    focal_shift : float, meters
        The shift in the propagation distance of the wavefront from focus.
    shift : Array = np.zeros(2)
        The (x, y) shift to apply to the wavefront in the output plane.
    pixel : bool = False
        If True the shift value is assumed to be in units of pixels, else the
        physical units of the output plane.
    """
    self.focal_shift = float(focal_shift)
    super().__init__(
        shift=shift,
        pixel=pixel,
        focal_length=focal_length,
        pixel_scale=pixel_scale,
        npixels=npixels,
    )

apply(wavefront)

Applies the layer to the wavefront.

Parameters:

Name Type Description Default
wavefront Wavefront

The wavefront to operate on.

required

Returns:

Name Type Description
wavefront Wavefront

The transformed wavefront.

Source code in src/dLux/layers/propagators.py
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
def apply(self: Propagator, wavefront: Wavefront) -> Wavefront:
    """
    Applies the layer to the wavefront.

    Parameters
    ----------
    wavefront : Wavefront
        The wavefront to operate on.

    Returns
    -------
    wavefront : Wavefront
        The transformed wavefront.
    """
    return wavefront.propagate_fresnel(
        self.npixels,
        self.pixel_scale,
        self.focal_length,
        self.focal_shift,
        self.shift,
        self.pixel,
    )