TECHNICAL FIELD

The present invention relates to an electromagnetic wave phase/amplitude generation device, an electromagnetic wave phase/amplitude generation method, and an electromagnetic wave phase/amplitude generation program.

BACKGROUND ART

Conventionally, technology for radiating electromagnetic waves to an imaging object, imaging scattered electromagnetic waves generated when the imaging object scatters the radiated electromagnetic waves via a scattering plate having a random pattern in which a magnitude for attenuating the electromagnetic waves differs according to each region, and generating complex amplitude indicating a phase and amplitude of the electromagnetic waves scattered by the imaging object from a captured image and the random pattern is known (for example, Non-Patent Document 1).

CITATION LIST

Non-Patent Literature

[Non-Patent Document 1]

Single-shot phase imaging with a coded aperture (OPTICS LETTERS/Vol. 39, No. 22/Nov. 15, 2014)

SUMMARY OF INVENTION

Technical Problem

In the conventional technology, it is possible to generate complex amplitude indicating a phase and amplitude of electromagnetic waves scattered by an imaging object in one imaging process. However, a scattering plate weakens the electromagnetic waves scattered from the imaging object, a signal-to-noise ratio decreases, and noise increases. Also, if a state of the electromagnetic waves radiated to the imaging object is strengthened by an amount corresponding to the electromagnetic waves weakened by the scattering plate, there is a problem in that invasiveness with respect to the imaging object becomes high and the imaging object is adversely affected due to this high invasiveness.

An objective of the present invention is to provide an electromagnetic wave phase/amplitude generation device, an electromagnetic wave phase/amplitude generation method, and an electromagnetic wave phase/amplitude generation program having a high signal-to-noise ratio and low invasiveness to an imaging object.

Solution to Problem

According to an aspect of the present invention, there is provided an electromagnetic wave phase/amplitude generation device including: a radiation unit configured to radiate electromagnetic waves of a random radiation pattern on a spatial frequency in which a state of the electromagnetic waves to be radiated for each divided region is determined to an imaging object; an imaging unit configured to generate a captured image by imaging scattered electromagnetic waves that are electromagnetic waves generated when the imaging object scatters the electromagnetic waves of the radiation pattern radiated by the radiation unit; and a generation unit configured to generate information indicating at least a phase and amplitude of the electromagnetic waves from the imaging object by performing an arithmetic sparsity constraint operation according to sparsity of the imaging object on the basis of the captured image generated by the imaging unit, information indicating the radiation pattern, and information indicating a signal of the imaging object.

Also, according to an aspect of the present invention, in the electromagnetic wave phase/amplitude generation device, the information indicating the radiation pattern includes distance-specific wavefront pattern information indicating states of wavefronts of the electromagnetic waves at a plurality of distances and the generation unit is configured to generate information indicating a phase and amplitude of a tomographic plane of the imaging object by performing the arithmetic sparsity constraint operation according to the sparsity of the imaging object further on the basis of the distance-specific wavefront pattern information.

Also, according to an aspect of the present invention, in the electromagnetic wave phase/amplitude generation device, the generation unit is configured to generate the information indicating at least the phase and the amplitude of the electromagnetic waves by iteratively generating the information indicating at least the phase and the amplitude of the electromagnetic waves on the basis of the generated information indicating at least the phase and the amplitude of the electromagnetic waves and information indicating a signal of the imaging object.

Also, according to an aspect of the present invention, in the electromagnetic wave phase/amplitude generation device, first resolution that is resolution of the imaging unit is lower than second resolution that is resolution of the arithmetic sparsity constraint operation of the generation unit, and the generation unit is configured to generate the information indicating at least the phase and the amplitude of the electromagnetic waves at resolution higher than the first resolution by iteratively generating the information indicating at least the phase and the amplitude of the electromagnetic waves further on the basis of a correspondence relationship between the first resolution and the second resolution.

Also, according to an aspect of the present invention, in the electromagnetic wave phase/amplitude generation device, the random radiation pattern on the spatial frequency is a pattern in which a spectrum uniformly spreads on the spatial frequency.

Also, according to an aspect of the present invention, in the electromagnetic wave phase/amplitude generation device, the electromagnetic waves include at least one selected from the group consisting of visible rays, X rays, electron rays, ultraviolet rays, infrared rays, terahertz waves, millimeter waves, and microwaves.

Also, according to an aspect of the present invention, there is provided an electromagnetic wave phase/amplitude generation method including: a radiation step of radiating electromagnetic waves of a random radiation pattern on a spatial frequency in which a state of the electromagnetic waves to be radiated for each divided region is determined to an imaging object; an imaging step of generating a captured image by imaging scattered electromagnetic waves that are electromagnetic waves generated when the imaging object scatters the electromagnetic waves of the radiation pattern radiated from the radiation step; and a generation step of generating information indicating at least a phase and amplitude of the electromagnetic waves from the imaging object by performing an arithmetic sparsity constraint operation according to sparsity of the imaging object on the basis of the captured image generated from the imaging step, information indicating the radiation pattern, and information indicating a signal of the imaging object.

Also, according to an aspect of the present invention, there is provided an electromagnetic wave phase/amplitude generation program for causing a computer to execute: a radiation step of radiating electromagnetic waves of a random radiation pattern on a spatial frequency in which a state of the electromagnetic waves to be radiated for each divided region is determined to an imaging object; an imaging step of generating a captured image by imaging scattered electromagnetic waves that are electromagnetic waves generated when the imaging object scatters the electromagnetic waves of the radiation pattern radiated from the radiation step; and a generation step of generating information indicating at least a phase and amplitude of the electromagnetic waves from the imaging object by performing an arithmetic sparsity constraint operation according to sparsity of the imaging object on the basis of the captured image generated from the imaging step, information indicating the radiation pattern, and information indicating a signal of the imaging object.

Advantageous Effects of Invention

According to the present invention, it is possible to provide an electromagnetic wave phase/amplitude generation device, an electromagnetic wave phase/amplitude generation method, and an electromagnetic wave phase/amplitude generation program having a high signal-to-noise ratio and low invasiveness to an imaging object.

