Abstract: Provided are a method and apparatus for optimizing a holographic display. The holographic display back-propagates target field data including generating a predicted hologram by a plurality of planes in a depth direction to a complex plane of a space light modulator (SLM), converts the predicted hologram into a binary hologram, generates predicted field data by forward-propagating the binary hologram to a reproduction plane through an optical system simulation model, calculates a loss function between the predicted field data and the target field data, generates a new predicted hologram for the predicted field data by using a stochastic gradient descent (SGD) method to reduce a value of the loss function, and repeats the generation of the new predicted hologram until the value of the loss function is less than a predefined threshold.

Abstract: A method of designing an optical system including a dome light and coaxial light, includes: determining a distance between the dome light and the coaxial light based on a radius reduction according to a hole of the dome light; determining a size of the coaxial light based on an optical path of a light ray emitted from the coaxial light; and determining a structure of a printed circuit board (PCB) in the dome light based on an optical path through which the light ray emitted from the coaxial light is reflected by an object.

Abstract: An example electronic device may include a foldable housing, including a hinge, a first housing connected to the hinge and including a first surface facing a first direction and a second surface facing a second direction opposite the first direction, and a second housing connected to the hinge, including a third surface facing a third direction and a fourth surface facing a fourth direction opposite the third direction, the second housing configured to be foldable with respect to the first housing about the hinge, wherein the first surface faces the third surface in a folded state of the electronic device; a display extending from the first surface to the third surface to provide the first surface and the third surface and including a touch controller configured to control a receiving function of an input on the display; a processor disposed inside the first or second housing and operatively coupled to the display; and a memory operatively connected to the processor, wherein the memory may store instructions

Abstract: A holographic aberration correction method and apparatus are provided. The holographic aberration correction apparatus includes: generating a plurality of sub-holograms in a hologram, as a matrix; calculating a plurality of eigenmodes and an eigenvalue and a weight corresponding to each of the eigenmodes by performing singular value decomposition on the matrix; selecting a predefined number of eigenmodes in the order of largest eigenvalues; calculating a plurality of first results which are obtained by multiplying a plurality of identical images by respective weights corresponding to the plurality of selected eigenmodes; calculating a plurality of second results by performing convolution of the plurality of first results and the plurality of selected eigenmodes, respectively; and generating an aberration-corrected hologram by adding the plurality of second results.

Abstract: An atypical metasurface, includes: a 2-dimensional plane; and a plurality of atypical unit structures periodically arranged on the 2-dimensional plane, wherein each of the plurality of atypical unit structures has an atypical pattern that is not periodic.

Abstract: Provided is a method of generating a hologram, the method including generating a kernel and a neural network configured to model an aberration of a holographic display device, obtaining second image data output from the neural network to which first image data obtained by propagating a first hologram based on the kernel is input, updating the kernel and the neural network based on comparing the second image data and predetermined image data, and generating a second hologram based on the kernel and the neural network.

Abstract: A method of designing an optical system including a dome light and coaxial light, includes: determining a distance between the dome light and the coaxial light based on a radius reduction according to a hole of the dome light; determining a size of the coaxial light based on an optical path of a light ray emitted from the coaxial light; and determining a structure of a printed circuit board (PCB) in the dome light based on an optical path through which the light ray emitted from the coaxial light is reflected by an object.

Abstract: A holographic display apparatus and a hologram optimization method for the apparatus are provided. The holographic display apparatus includes a focus-forming optical element configured to form a plurality of foci by receiving plane waves; a collimating lens configured to propagate, as plane waves, light incident through the plurality of foci; and a spatial light modulator configured to generate a holographic image by overlapping a plurality of plane waves incident from the collimating lens.

Abstract: A holographic aberration correction method and apparatus are provided. The holographic aberration correction apparatus includes: generating a plurality of sub-holograms in a hologram, as a matrix; calculating a plurality of eigenmodes and an eigenvalue and a weight corresponding to each of the eigenmodes by performing singular value decomposition on the matrix; selecting a predefined number of eigenmodes in the order of largest eigenvalues; calculating a plurality of first results which are obtained by multiplying a plurality of identical images by respective weights corresponding to the plurality of selected eigenmodes; calculating a plurality of second results by performing convolution of the plurality of first results and the plurality of selected eigenmodes, respectively; and generating an aberration-corrected hologram by adding the plurality of second results.

Abstract: A display apparatus including a volume grating-based combiner is disclosed. The display apparatus includes: an image providing device; and a combiner, wherein the combiner includes a plurality of volume gratings configured to diffract light containing an image, which is emitted from the image providing device, each volume grating has a first surface and a second surface facing each other, and each volume grating is further configured to diffract light incident on the first surface and transmit therethrough light incident on the second surface without diffraction.

Abstract: A method and apparatus for filtering noise for a holographic display are provided. The noise filtering apparatus includes a first filter implemented using a volume grating for filtering DC noise in light modulated by a spatial light modulator or a second filter implemented using a volume grating or a thin-film filter, which filters high-order noise in the light.

Abstract: A steel sheet with excellent phosphatability, according to one embodiment of the present invention, comprises, by wt %, 0.02-0.06% of carbon (C), 0.01% or less of silicon (Si) (excluding 0%), 0.1-0.24% of manganese (Mn), 0.02% or less of aluminum (Al) (excluding 0%), 0.015-0.04% of phosphorus (P), and the balance of iron (Fe) and inevitable impurities, and has an oxide layer having a thickness of 10 nm or less inward from the surface of the steel sheet, and satisfies the following formula 1. ([Mn]+[Si]+[Al])/(3×[P])?0.6 ??[Formula 1] (In formula 1, [Mn], [Si], [Al] and [P] mean the maximum amount of each element when elemental analysis is carried out in the thickness direction of the oxide layer.

Abstract: A display apparatus including a volume grating-based combiner is disclosed. The display apparatus includes: an image providing device; and a combiner, wherein the combiner includes a plurality of volume gratings configured to diffract light containing an image, which is emitted from the image providing device, each volume grating has a first surface and a second surface facing each other, and each volume grating is further configured to diffract light incident on the first surface and transmit therethrough light incident on the second surface without diffraction.

Abstract: A hologram profile optimization method includes: setting a first hologram profile as a variable; and performing an optimization cycle a predetermined number of times, wherein the optimization cycle includes encoding the first hologram profile into a binary hologram profile by using an ApproxSign function; calculating a field value of a holographic image on a display surface for the binary hologram profile, considering high-order diffraction term noise of the holographic image by using a tiling function; calculating an intensity of the holographic image on the display surface; calculating a loss function value based on a difference between the intensity of the holographic image and an intensity of a target image; and updating the first hologram profile to a second hologram profile based on the loss function value.

Abstract: A retinal projection display device is provided. The retinal projection display device includes a light source configured to emit light, a spatial light modulator configured to generate diffracted light by diffracting the emitted light, a holographic optical element configured to reflect the diffracted light by duplicating the diffracted light into a plurality of complex wavefronts, and a field lens configured to focus the plurality of complex wavefronts to a plurality of respective focal points in an eye-box, wherein the plurality of complex wavefronts overlap each other.

Abstract: Provided is a hydraulic machine. A pump pressurizes fluid using power provided by a power source. An actuator works using the pressurized fluid from the pump. A recovery part recovers energy from fluid discharged from the actuator. A first operator input device receives a desired input from operator to select an eco-mode or a boost mode. The recovery part includes an accumulator storing hydraulic energy by receiving the fluid discharged from the actuator and an assist unit assisting the power source using the hydraulic energy stored in the accumulator. The controller controls the pump such that output power of the pump does not exceed P1max when the eco-mode is selected or the assist unit does not assist the power source and that the output power does not exceed P2max when the boost mode is selected and the assist unit assists the power source, where P1max<P2max.

Abstract: Provided is a multi-image display apparatus including an image forming device configured to form a first image, a first polarization plate configured to transmit a first polarization component of the first image provided from the image forming device, a second polarization plate configured to transmit a second polarization component of a second image that is provided from a path different from the first image, the second polarization component being different from the first polarization component, a screen configured to reflect and diffuse the first image, and transmit the second image, and a polarization selective lens configured to focus the first image having the first polarization component, and transmit the second image having the second polarization component without refraction.

Abstract: An optical apparatus and a near-eye display apparatus including the same are provided. The optical apparatus includes a display panel configured to form an image, a first polarization rotator configured to electrically control a light emitted from the display panel to have a first polarization state, a first ¼ wave plate configured to convert the first polarization state of a light transmitted from the first polarization rotator to a second polarization state, and an optical element group configured to display a first image having a first viewing angle and a second image having a second viewing angle that is greater than the first viewing angle based on the second polarization state of a light transmitted from the first ¼ wave plate.

Abstract: A multi-image display apparatus includes a light source configured to emit a first wavelength light, a second wavelength light, and a third wavelength light, a spatial light modulator configured to modulate the first wavelength light, the second wavelength light, and the third wavelength light to form a first image including a first color holographic image, a second color holographic image, and a third color holographic image, a polarization selective lens configured to focus the first image having only a first polarization component and transmit a second image having only a second polarization component without refraction, the second image being provided to the polarization selective lens along a different path from the first image, wherein chromatic aberration of the polarization selective lens is offset by adjusting a depth of the first color holographic image, the second color holographic image, and the third color holographic image.

Abstract: Provided is a hydraulic machine. A pump pressurizes fluid using power provided by a power source. An actuator works using the pressurized fluid from the pump. A recovery part recovers energy from fluid discharged from the actuator. A first operator input device receives a desired input from an operator to select an eco-mode or a boost mode. The recovery part includes an accumulator storing hydraulic energy by receiving the fluid discharged from the actuator and an assist unit assisting the power source using the hydraulic energy stored in the accumulator. The controller controls the pump such that output power of the pump does not exceed Plmax when the eco-mode is selected or the assist unit does not assist the power source and that the output power does not exceed P2max when the boost mode is selected and the assist unit assists the power source, where Plmax < P2max.