Hyperspectral imaging device capable of acquiring polarization information and optical element thereof
An imaging device includes an optical element including a transparent substrate, and a plurality of structures disposed on or in the transparent substrate in a plane direction of the transparent substrate, an imaging element in which a plurality of pixels including photoelectric conversion elements are disposed, and a signal processing unit configured to generate an image signal based on an electrical signal acquired from the imaging element, wherein the optical element forms an image in which a point spread function of each wavelength is convoluted on a plurality of pixels corresponding to each polarized light component depending on polarized light components by outputting light in a state in which the optical element has different point spread functions for respective wavelengths, the plurality of structures have the same height in a side view, and the signal processing unit reconstructs an image in which a point spread function is convoluted.
1. An imaging device comprising:
an optical element including a transparent substrate, and a plurality of structures disposed on or in the transparent substrate in a plane direction of the transparent substrate;
an imaging element in which a plurality of pixels including photoelectric conversion elements are disposed; and
a signal processing unit, including one or more processors, configured to generate an image signal based on an electrical signal acquired from the imaging element, wherein
the optical element is configured to: (i) polarize incident light into multiple polarized light components, each polarized light component having a different polarization direction, and (ii) cause dispersion that separates each polarized component into different wavelengths, wherein the optical element is further configured to form an image in which a point spread function of each of the different wavelengths is convoluted on the plurality of pixels corresponding to each polarized light component among the multiple polarized light components by outputting light in a state in which the optical element has different point spread functions for respective wavelengths,
the plurality of structures have the same height in a side view, and
the signal processing unit reconstructs an image in which a point spread function of each wavelength is convoluted for each polarized light component.
2. The imaging device according to claim 1 , wherein the signal processing unit reconstructs an image for each polarized light component based on a matrix defined by an imaging process of the optical element and an image in which a point spread function of each wavelength is convoluted.
3. The imaging device according to claim 2 , wherein the signal processing unit solves an optimization problem having the matrix defined by the imaging process of the optical element and the image in which the point spread function of each wavelength is convoluted as inputs using a model configured by a neural network.
4. The imaging device according to claim 1 , wherein each of the plurality of structures is a columnar structure having a refractive index higher than a refractive index of the transparent substrate and providing an optical phase delay amount corresponding to a cross-sectional shape to the incident light,
the plurality of structures have a cross-sectional shape which is set according to an optical phase amount delay distribution for forming an image in which a point spread function of each wavelength for the pixels is convoluted on the plurality of pixels corresponding to each polarized light component among the multiple polarized light components, and are arranged according to the optical phase amount delay distribution for forming the image in which the point spread function of each wavelength for the pixels is convoluted on the plurality of pixels corresponding to each polarized light component among the multiple polarized light components.
5. The imaging device according to claim 1 , wherein a cross-sectional shape of each of the plurality of structures is a 2-order rotationally symmetrical shape.
6. The imaging device according to claim 1 , wherein a barrier for absorbing light is provided immediately below a boundary of polarization separation regions in the optical element.
7. The imaging device according to claim 1 , further including a polarizing filter provided between the optical element and the imaging element and making a polarization transmission axis coincident with a polarization direction corresponding to the pixels positioned immediately below the polarizing filter.
8. An optical element comprising a transparent substrate, and a plurality of structures disposed on or in the transparent substrate in a plane direction of the transparent substrate, wherein
the optical element is configured to: (i) polarize incident light into multiple polarized light components, each polarized light component having a different polarization direction, and ii) cause dispersion that separates each polarized component into different wavelengths, wherein the optical element is further configured to form an image in which a point spread function of each of the different wavelengths is convoluted on a plurality of pixels of an imaging element corresponding to each polarized light component among the multiple polarized light components by outputting light in a state in which the optical element has different point spread functions for respective wavelengths, and
the plurality of structures have the same height in a side view.