A diffraction structure includes a supporting layer, a high refractive index layer, and a low refractive index layer. The high refractive index layer has a first refractive index, is formed above the supporting layer, configures a waveguide guiding input light input from an input terminal along a specific direction, and includes an opening section formed along the specific direction. The low refractive index layer has a second refractive index lower that the first refractive index, and is formed so as to cover the high refractive index layer and fill the opening section. The opening section modifies the input light in at least one of direction or speed according to a wavelength of the input light, and outputs the modified light as output light.

An image pickup apparatus (10) capable of generating a plurality of output images having different focus positions by reconstructing an input image, the image pickup apparatus includes an input image obtaining unit (100) configured to obtain the input image, an image processing unit (105) configured to generate a display image from the input image, and a display unit (106) configured to display the display image, and the image processing unit (105) obtains a focus control range in which a focus position is controllable, and generates the display image including information on the focus control range by using at least a part of the input image.

An eyepiece includes a substrate and an in-coupling grating patterned on a single side of the substrate. A first grating coupler is patterned on the single side of the substrate and has a first grating pattern. The first grating coupler is optically coupled to the in-coupling grating. A second grating coupler is patterned on the single side of the substrate adjacent to the first grating coupler. The second grating coupler has a second grating pattern different from the first grating pattern. The second grating coupler is optically coupled to the in-coupling grating.

An eyepiece includes a substrate and an in-coupling grating patterned on a single side of the substrate. A first grating coupler is patterned on the single side of the substrate and has a first grating pattern. The first grating coupler is optically coupled to the in-coupling grating. A second grating coupler is patterned on the single side of the substrate adjacent to the first grating coupler. The second grating coupler has a second grating pattern different from the first grating pattern. The second grating coupler is optically coupled to the in-coupling grating.