AiryDisk2D

class astropy.modeling.functional_models.AiryDisk2D(amplitude=1, x_0=0, y_0=0, radius=1, **kwargs)

Bases: astropy.modeling.Fittable2DModel

Two dimensional Airy disk model.

Parameters:

amplitude : float

Amplitude of the Airy function.

x_0 : float

x position of the maximum of the Airy function.

y_0 : float

y position of the maximum of the Airy function.

radius : float

The radius of the Airy disk (radius of the first zero).

Other Parameters:  

fixed : a dict

A dictionary {parameter_name: boolean} of parameters to not be varied during fitting. True means the parameter is held fixed. Alternatively the fixed property of a parameter may be used.

tied : dict

A dictionary {parameter_name: callable} of parameters which are linked to some other parameter. The dictionary values are callables providing the linking relationship. Alternatively the tied property of a parameter may be used.

bounds : dict

A dictionary {parameter_name: boolean} of lower and upper bounds of parameters. Keys are parameter names. Values are a list of length 2 giving the desired range for the parameter. Alternatively the min and max properties of a parameter may be used.

eqcons : list

A list of functions of length n such that eqcons[j](x0,*args) == 0.0 in a successfully optimized problem.

ineqcons : list

A list of functions of length n such that ieqcons[j](x0,*args) >= 0.0 is a successfully optimized problem.

See also

Box2D, TrapezoidDisk2D, Gaussian2D

Notes

Model formula:

\[f(r) = A \left[\frac{2 J_1(\frac{\pi r}{R/R_z})}{\frac{\pi r}{R/R_z}}\right]^2\]

Where \(J_1\) is the first order Bessel function of the first kind, \(r\) is radial distance from the maximum of the Airy function (\(r = \sqrt{(x - x_0)^2 + (y - y_0)^2}\)), \(R\) is the input radius parameter, and \(R_z = 1.2196698912665045\)).

For an optical system, the radius of the first zero represents the limiting angular resolution and is approximately 1.22 * lambda / D, where lambda is the wavelength of the light and D is the diameter of the aperture.

See [R2525] for more details about the Airy disk.

References

[R2525]

(1, 2) https://en.wikipedia.org/wiki/Airy_disk

Attributes Summary

amplitude
input_units
param_names
radius
x_0
y_0

Methods Summary

evaluate(x, y, amplitude, x_0, y_0, radius)

Two dimensional Airy model function

Attributes Documentation

amplitude

input_units

param_names = ('amplitude', 'x_0', 'y_0', 'radius')

radius

x_0

y_0

Methods Documentation

classmethod evaluate(x, y, amplitude, x_0, y_0, radius)

Two dimensional Airy model function