FraunhoferPropagator

class hcipy.propagation.FraunhoferPropagator(input_grid, output_grid, focal_length=1)

Bases: AgnosticOpticalElement

A monochromatic perfect lens propagator.

This implements the propagation of a wavefront through a perfect lens. The wavefront is assumed to be exactly in the front focal plane of the lens and is propagated to the back focal plane. The implementation follows [Goodman2005].

[Goodman2005]

Goodman, J.W., 2005 Introduction to Fourier optics. Roberts and Company Publishers.

Parameters:

input_gridGrid

The grid on which the incoming wavefront is defined.

output_gridGrid

The grid on which the outgoing wavefront is to be evaluated.

focal_lengthscalar

The focal length of the lens system.

Attributes Summary

focal_length

Methods Summary

backward(wavefront, *args, **kwargs)	Propagate a wavefront backward through the optical element.
closest_fft_wavelength(target_wavelength)	Find the wavelength closest to target_wavelength for which the propagation could be performed with a Fast Fourier Transform.
forward(wavefront, *args, **kwargs)	Propagate a wavefront forward through the optical element.
get_input_grid(output_grid, wavelength)	Calculate a best guess for the input grid given an output grid and wavelength.
get_output_grid(input_grid, wavelength)	Calculate a best guess for the output grid given an input grid and wavelength.
make_instance(instance_data, input_grid, ...)	Make an instance for this specific input_grid, output_grid, wavelength.

Attributes Documentation

focal_length

Methods Documentation

backward(wavefront, *args, **kwargs)

Propagate a wavefront backward through the optical element.

A backward propagation is a literal backward propagation through the element. It is not (in general) the inverse of the forward propagation, except in cases where energy is conserved.

This function will be implemented by the derived class.

Parameters:

wavefrontWavefront

The wavefront to propagate.

Returns:

Wavefront

The propagated wavefront.

closest_fft_wavelength(target_wavelength)

Find the wavelength closest to target_wavelength for which the propagation could be performed with a Fast Fourier Transform.

Note

A Fast Fourier Transform is not necessarily used for the returned wavelength; the transform to use is decided by make_fourier_transform(). The returned wavelength only guarantees that an FFT is a valid option, and will be used if it is estimated to be the fastest.

Parameters:

target_wavelengthscalar or array_like

The wavelength(s) of interest.

Returns:

Array

The wavelength(s) closest to target_wavelength that can be propagated with an FFT.

Raises:

ValueError

If appropriate wavelengths could not be found.

forward(wavefront, *args, **kwargs)

Propagate a wavefront forward through the optical element.

This will be implemented by the derived class.

Parameters:

wavefrontWavefront

The wavefront to propagate.

Returns:

Wavefront

The propagated wavefront.

get_input_grid(output_grid, wavelength)

Calculate a best guess for the input grid given an output grid and wavelength.

This function is intended to be implemented by a derived class.

Parameters:

output_gridGrid

The output grid.

wavelengthscalar

The wavelength.

Returns:

Grid

The best-guess input grid based on the given output grid and wavelength.

get_output_grid(input_grid, wavelength)

Calculate a best guess for the output grid given an input grid and wavelength.

This function is intended to be implemented by a derived class.

Parameters:

input_gridGrid

The input grid.

wavelengthscalar

The wavelength.

Returns:

Grid

The best-guess output grid based on the given input grid and wavelength.

make_instance(instance_data, input_grid, output_grid, wavelength)

Make an instance for this specific input_grid, output_grid, wavelength.

This function is intended to be implemented by a derived class. Any properties evaluated for the instance can be stored into the instance_data object which is stored in the internal cache.

Parameters:

instance_dataInstanceData

An object storing all data for this instance. This object can be modified this function.

input_gridGrid or None

The input grid.

output_gridGrid or None

The output grid.

wavelengthscalar or None

The wavelength.