Files
cdtools/CDTools/tools/polarization/polarization.py
T
2021-08-03 19:54:18 -04:00

227 lines
6.8 KiB
Python

import numpy as numpy
import torch as t
import math
from math import sin
from math import cos
__all__ = ['apply_linear_polarizer',
'apply_phase_retardance',
'apply_half_wave_plate',
'apply_quarter_wave_plate',
'apply_circular_polarizer',
'apply_jones_matrix']
def apply_linear_polarizer(probe, polarizer, multiple_modes=True, transpose=True):
"""
Applies a linear polarizer to the probe
Parameters:
----------
probe: t.Tensor
A (N)(P)x2xMxL tensor representing the probe, MxL - the size of the probe
The angle between the fast-axis of the linear polarizer and the horizontal axis
polarizer: t.Tensor
A 1D tensor (N) representing the polarizer angles for each of the patterns (or a single tensor of shape (1))
Returns:
--------
linearly polarized probe: t.Tensor
(N)(P)x2x1xMxL
"""
if len(polarizer.shape) == 1:
print('polarizer', polarizer)
theta = math.radians(polarizer)
jones_matrices = t.tensor([[(cos(theta)) ** 2, sin(2 * theta) / 2], [sin(2 * theta) / 2, sin(theta) ** 2]]).to(dtype=t.cfloat)
else:
pol_cos = lambda idx: cos(math.radians(polarizer[idx]))
pol_sin = lambda idx: sin(math.radians(polarizer[idx]))
jones_matrices = t.stack(([t.tensor([[(pol_cos(idx)) ** 2, pol_sin(idx) * pol_cos(idx)], [pol_sin(idx) * pol_cos(idx), (pol_sin(idx)) ** 2]]).to(dtype=t.cfloat) for idx in range(len(polarizer))]))
return apply_jones_matrix(probe, jones_matrices, transpose=transpose, multiple_modes=multiple_modes)
def apply_jones_matrix(probe, jones_matrix, transpose=True, multiple_modes=True):
"""
Applies a given Jones matrix to the probe
Parameters:
----------
probe: t.Tensor
A (N)(P)x2xMxL tensor representing the probe
jones_matrix: t.tensor
(N)x2x2x(M)x(L)
Returns:
--------
a probe with the jones matrix applied: t.Tensor
(N)(P)x2xMxL
Assume that if the probe has a dimension (N), so does the jones matrix
"""
if multiple_modes:
if transpose:
if len(jones_matrix.shape) >= 4:
jones_matrix = jones_matrix[..., None, :, :, :, :]
else:
jones_matrix = jones_matrix[..., None, :, :, None, None]
probe = probe[..., None, :, :]
# if jones matrices do not differ from pattern to pattern
if len(probe.shape) > len(jones_matrix.shape):
jones_matrix = jones_matrix[None, ...]
jones_matrix = jones_matrix.transpose(-1, -3).transpose(-2, -4)
# (N)1xMxLx2x2 or (N)1x1x1x2x2
probe = probe.transpose(-1, -3).transpose(-2, -4)
output = t.matmul(jones_matrix, probe).transpose(-2, -4).transpose(-1, -3).squeeze(-3)
# (N)Px2xMxL
else:
if len(jones_matrix.shape) < 4:
jones_matrix = jones_matrix[..., None, :, :, :, :]
probe = t.stack((probe, probe), dim=-4)
output = t.sum(jones_matrix * probe, dim=-3)
#(N)x2xMxL
else:
if transpose:
if len(jones_matrix.shape) < 4:
jones_matrix = jones_matrix[..., None, None]
probe = probe[..., None, :, :]
# if jones matrices do not differ from pattern to pattern
if len(probe.shape) > len(jones_matrix.shape):
jones_matrix = jones_matrix[None, ...]
probe = probe.transpose(-1, -3).transpose(-2, -4)
jones_matrix = jones_matrix.transpose(-1, -3).transpose(-2, -4)
output = t.matmul(jones_matrix, probe).transpose(-2, -4).transpose(-1, -3).squeeze(-3)
else:
if len(jones_matrix.shape) < 4:
jones_matrix = jones_matrix[..., None, None]
probe = t.stack((probe, probe), dim=-4)
output = t.sum(jones_matrix * probe, dim=-3)
return output
def apply_phase_retardance(probe, phase_shift):
"""
Shifts the y-component of the field wrt the x-component by a given phase shift
Parameters:
----------
probe: t.Tensor
A (...)x2x1xMxL tensor representing the probe
phase_shift: float
phase shift in degrees
Returns:
--------
probe: t.Tensor
(...)x2x1xMxL
"""
probe = probe.to(dtype=t.cfloat)
jones_matrix = t.tensor([[1, 0], [0, phase_shift]])
probe = probe.transpose(-1, -3).transpose(-2, -4)
polarized_probe = t.matmul(jones_matrix.to(dtype=t.cfloat), probe)
# Transpose it back
return polarized_probe.transpose(-1, -3).transpose(-2, -4)
def apply_circular_polarizer(probe, left_polarized=True):
"""
Applies a circular polarizer to the probe
Parameters:
----------
probe: t.Tensor
A (...)x2x1xMxL tensor representing the probe
left_polarizd: bool
True for the left-polarization, False for the right
Returns:
--------
circularly polarized probe: t.Tensor
(...)x2x1xMxL
"""
probe = probe.to(dtype=t.cfloat)
if left_polarized:
jones_matrix = (1/2 * t.tensor([[1, -1j], [1j, 1]]))
else:
jones_matrix = 1/2 * t.tensor([[1, 1j], [-1j, 1]])
probe = probe.transpose(-1, -3).transpose(-2, -4)
polarized_probe = t.matmul(jones_matrix.to(dtype=t.cfloat), probe)
# Transpose it back
return polarized_probe.transpose(-1, -3).transpose(-2, -4)
def apply_quarter_wave_plate(probe, fast_axis_angle):
"""
Parameters:
----------
probe: t.Tensor
A (...)x2x1xMxL tensor representing the probe, MxL - the size of the probe
fast_axis_angle: float
The angle between the fast-axis of the polarizer and the horizontal axis
Returns:
--------
polarized probe: t.Tensor
(...)x2x1xMxL
"""
probe = probe.to(dtype=t.cfloat)
theta = math.radians(fast_axis_angle)
exponent = t.exp(-1j * math.pi / 4 * t.ones(2, 2))
jones_matrix = exponent* t.tensor([[(cos(theta))**2 + 1j * (sin(theta))**2, (1 - 1j) * sin(theta) * cos(theta)], [(1 - 1j) * sin(theta) * cos(theta), (sin(theta))**2 + 1j * (cos(theta))**2]])
probe = probe.transpose(-1, -3).transpose(-2, -4)
polarized_probe = t.matmul(jones_matrix.to(dtype=t.cfloat), probe)
# Transpose it back
return polarized_probe.transpose(-1, -3).transpose(-2, -4)
def apply_half_wave_plate(probe, fast_axis_angle):
"""
Parameters:
----------
probe: t.Tensor
A (...)x2x1xMxL tensor representing the probe, MxL - the size of the probe
fast_axis_angle: float
The angle between the fast-axis of the polarizer and the horizontal axis
Returns:
--------
polarized probe: t.Tensor
(...)x2x1xMxL
"""
probe = probe.to(dtype=t.cfloat)
theta = math.radians(fast_axis_angle)
exponent = t.exp(-1j * math.pi / 2 * t.ones(2, 2))
jones_matrix = exponent * t.tensor([[(cos(theta))**2 - (sin(theta))**2, 2 * sin(theta) * cos(theta)], [2 * sin(theta) * cos(theta), (sin(theta))**2 - (cos(theta))**2]])
probe = probe.transpose(-1, -3).transpose(-2, -4)
polarized_probe = t.matmul(jones_matrix.to(dtype=t.cfloat), probe)
# Transpose it back
return polarized_probe.transpose(-1, -3).transpose(-2, -4)
# probe = t.rand(17, 7, 2, 6, 4)
# polarizer = t.rand(7)
# out = apply_linear_polarizer(probe, polarizer)
# out2 = apply_linear_polarizer(probe, polarizer, transpose=False)
# print(out.shape)
# print(out2.shape)
# a = t.ones(17, 8, 2, 3, 4)
# b = t.ones(2, 1, 1)
# probe = t.ones(5, 2, 3, 3)
# polarizer = t.tensor([45])
# exitw = apply_linear_polarizer(probe, polarizer)
# print(exitw[:, 0, :, :])
# print('y', exitw[:, 1, :, :])
a = t.ones(2, 4)
print(t.sum(a, dim=1).shape)