from typing import Generic
import dataclasses
import astropy.units as u
import named_arrays as na
import optika
import furst
__all__ = [
"Grating",
]
[docs]
@dataclasses.dataclass(eq=False, repr=False)
class Grating(
optika.mixins.Rollable,
optika.mixins.Yawable,
optika.mixins.Pitchable,
optika.mixins.Translatable,
furst.abc.AbstractRowlandComponent,
Generic[
furst.typevars.SagT,
furst.typevars.MaterialT,
furst.typevars.RulingT,
],
):
"""
A model of the FURST diffraction grating.
This is a concave, spherical diffraction grating
a rectangular aperture.
Examples
--------
Plot an exaggerated grating on the Rowland circle.
.. jupyter-execute::
import numpy as np
import matplotlib.pyplot as plt
import astropy.units as u
import astropy.visualization
import named_arrays as na
import optika
import furst
# Define the Rowland circle
rowland_radius = 1000 * u.mm
a = na.linspace(0, 360, axis="angle", num=1001) * u.deg
rowland_circle = rowland_radius * na.Cartesian3dVectorArray(
x=np.sin(a),
z=np.cos(a),
)
# Define the grating model
grating = furst.gratings.Grating(
sag=optika.sags.SphericalSag(
radius=-2 * rowland_radius,
),
width_clear=na.Cartesian2dVectorArray(
x=1000 * u.mm,
y=20 * u.mm,
),
material=optika.materials.Mirror(),
rowland_radius=rowland_radius,
rowland_azimuth=175 * u.deg,
)
# Plot the grating surface and the Rowland circle
with astropy.visualization.quantity_support():
fig, ax = plt.subplots()
grating.surface.plot(
ax=ax,
components=("z", "x"),
color="tab:blue",
)
na.plt.plot(
rowland_circle,
ax=ax,
components=("z", "x"),
color="black",
linestyle="dashed",
zorder=-10,
)
ax.set_aspect("equal")
"""
name: str = "grating"
"""
The human-readable name of this optic.
"""
sag: furst.typevars.SagT = None
"""
The sag profile of the grating surface.
"""
radius: u.Quantity | na.AbstractScalar = 0 * u.mm
"""
The radius of curvature of the optical surface.
"""
width_clear: u.Quantity | na.AbstractCartesian2dVectorArray = 0 * u.mm
"""
The height and width of the clear aperture of the grating.
"""
width_mech: u.Quantity | na.AbstractCartesian2dVectorArray = 0 * u.mm
"""
The height and width of the grating substrate.
"""
material: furst.typevars.MaterialT = None
"""
The coating material used to make the optic reflective
in the target spectral range.
"""
rulings: furst.typevars.RulingT = None
"""
A model of the grating ruling spacing and profile.
"""
rowland_radius: u.Quantity | na.AbstractScalar = 0 * u.mm
"""
The distance from the center of the Rowland circle to
the virtual image of the Sun within the feed optic.
"""
rowland_azimuth: u.Quantity | na.AbstractScalar = 0 * u.deg
"""
The azimuth of the virtual image of the Sun
on the Rowland circle, relative to the optic axis
of the instrument.
"""
translation: u.Quantity | na.AbstractCartesian3dVectorArray = 0 * u.mm
"""
Physical offset from the optic's nominal position on the
Rowland circle.
"""
pitch: u.Quantity | na.AbstractScalar = 0 * u.deg
"""
The angle of rotation about the vector tangent to the
Rowland circle.
"""
yaw: u.Quantity | na.AbstractScalar = 0 * u.deg
"""
The angle of rotation about the axis of symmetry
of the feed optic.
"""
roll: u.Quantity | na.AbstractScalar = 0 * u.deg
"""
The angle of rotation about the vector normal to
the Rowland circle.
"""
@property
def surface(self) -> optika.surfaces.Surface:
return optika.surfaces.Surface(
name=self.name,
sag=self.sag,
material=self.material,
aperture=optika.apertures.RectangularAperture(
half_width=self.width_clear / 2,
),
aperture_mechanical=optika.apertures.RectangularAperture(
half_width=self.width_mech / 2,
),
rulings=self.rulings,
is_pupil_stop=True,
transformation=self.transformation,
)
