There is provided a versatile optical element applicable both to an electrode layer required in a bank bill field and to an optical element required in an ID field. In an optical element (1) according to one embodiment of the present invention, a first layer (2) is arranged on a second layer (3) having a relief structure on a surface thereof, and a first region (4) and a second region (5) are provided. Electromagnetic waves incident at a preset specific angle from a side of the first layer (2) are totally reflected due to at least one of the relief structure in the first region (4) and a ratio of a refractive index of the second layer (3) with respect to a refractive index of the first layer (2), the electromagnetic waves incident at the specific angle from the side of the first layer (2) are not totally reflected but transmitted or refracted due to at least one of the relief structure in the second region (5) and the ratio of the refractive index of the second layer (3) with respect to the refractive index of the first layer (2), and only in case of observation performed from the specific angle on the first layer (2) side, the second region (5) has higher transparency than the first region (4), and a preset image is expressed by a transparency contrast therebetween.

A stereoscopic display device is provided for displaying a three-dimensional (3D) image as viewed by eyes consisting of a left eye and a right eye. In the display device, a single display screen, or separate left and right display screens, present a left image to the left eye but not the right eye, and present a right image to the right eye but not the left eye. A gaze distance tracker is configured to track gaze distance of the eyes. Variable-power lenses include a left variable-power lens arranged to provide eye accommodation for the left eye, and a right variable-power lens arranged to provide eye accommodation for the right eye. An electronic eye accommodation controller is configured to control the power of the variable power lenses to allow the image from the display to be focused on the retina, while the biological eye lens is accommodated to the gaze distance.

An imaging directional backlight apparatus including a waveguide, a light source array, for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, in which the steps may further include extraction features optically hidden to guided light, propagating in a first forward direction. Returning light propagating in a second backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources by waveguide facets and rear reflector images in cooperation. Viewing windows may be provided at first and second different window planes to improve uniformity in a lateral direction. Further, stray light may be reduced by inner and outer portions of reflective facets with different inclinations for the rear reflector.

An image display device includes a display panel displaying an image, and a diffractive element formed to operate in a 2D mode or a 3D mode so that the image of the display panel is perceived as a 2D image or a 3D image after passing through the diffractive element. In the image display device, the diffractive element includes a first substrate and a second substrate facing each other, a first electrode layer formed on the first substrate that includes a plurality of zones, a second electrode layer formed on the second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate. Further, when the diffractive element operates in the 3D mode, a common voltage is applied to the second electrode layer, and polarity of voltages applied to the first electrode layer with respect to the common voltage is inverted every zone.

The stereoscopic image display device which displays images corresponding to each of a plurality of viewpoints includes: a stereoscopic image display panel which includes a display panel in which a plurality of pixels are arranged and a light-ray separating module provided on the display panel for separating parallax images from each of the pixels towards a plurality of N-viewpoints (N is a natural number of 2 or larger) according to the layout direction of each of the pixels; an observer position measuring unit which measures an observing position of the observer who is facing the display surface; a relative position calculating unit which calculates a relative position of the observer with respect to the stereoscopic image display panel based on the measurement result; and an image generation processing unit which generates viewpoint image by corresponding to the relative position and outputs the image towards the stereoscopic image display panel.

A display apparatus (1) for use in displaying an image to a viewer, comprising a transparent optical waveguide display unit (2) arranged for receiving image-bearing light (4) into the optical waveguide display unit, for guiding the received light therealong to an output area (24) thereof, and for outputting from the output area the image-bearing light (6) collimated to present a viewable image. A light-emitting display screen (3) arranged adjacent to and behind the output area of the optical waveguide display unit is visible therethrough behind the output area (24). This combines the light from the light-emitting display screen (e.g. imagery) with the viewable image (6).

The present invention relates to a prism sheet for auto-stereoscopic 3D display that is installed on the top of a liquid crystal display panel. The prism sheet for auto-stereoscopic 3D display according to the present invention, comprises a plurality of prisms disposed parallel to each other, each of which includes a central portion of which the upper and lower surfaces are parallel to each other, the central portion having a width corresponding to a plurality of subpixel columns of the liquid crystal display panel; a left inclined portion that is installed on a left side of the central portion and refracts light such that a user can view the left half of the plurality of subpixel columns covered by the central portion, wherein the left half subpixel column is visible to a user; and a right inclined portion that is installed on a right side of the central portion and refract light such that the user can view the right half of the plurality of subpixel columns covered by the central portion.

A two-dimensional/three-dimensional (2D/3D) switchable display backlight and a 2D/3D switchable electronic display employ a switchable diffuser to support 2D/3D switching. The 2D/3D switchable display backlight includes a plate light guide, a multibeam diffraction grating to couple light out of the plate light guide and the switchable diffuser to intercept and selectably either pass or scatter light beams of the coupled-out light. The 2D/3D switchable electronic display includes the backlight and further includes a light valve array to modulate the coupled-out light. The switchable diffuser facilitates selectability between a three-dimensional pixel and a two-dimensional pixel of the 2D/3D switchable electronic display.

A laser system for generation of three-dimensional (3D) colored images is based on semiconductor laser sources generating laser light at a plurality of wavelengths. The laser source for each basic color range (red, green and blue) is formed on a single chip. The chip can be an array of the distributed feedback lasers or an array of distributed Bragg reflector lasers, each of which generates laser light at its own wavelength, or a COMB laser generating laser light at a plurality of wavelengths.

All light illuminates a two-dimensional (2D) display, and the light transmitted through the display or reflected by the display at a given color range impinges on an optical unit, containing a first optical element, e.g., a lens or a mirror, the focal length of which is wavelength-sensitive. Light at different wavelengths forms 2D images at different depths. Then, once the images created by the display and the laser pulses at each wavelength are synchronized, all images of the given colored range are perceived by the human's eyes as a single 3D image of this color range.

To fuse 3D images in red, green and blue that are formed at different positions, an optical element, e. g., a lens or a mirror is employed, the focal length of which is adjustable by mechanical motion, or deformation, or applying an electro-optic effect in an electric field. This optical element can be either the same first element with the wavelength-dependent focal length, or a different element. Then, once the light is switched between red, green and blue color ranges, the adjustable focal length of this element is adjusted such to compensate a change of the focal length of the first element, and the focal length of the entire optical unit is restored. Then the human's eyes average the perceived light and see a smoothly moving fully colored 3D image.

A measuring method and a measuring system are used for measuring contrast of a display device, including controlling the display device to display a first image, measuring brightness of a central area of the first image, controlling the display device to display a second image, measuring brightness of a central area of the second image, and determining the contrast. Both the first image and the second image have a plurality of areas with different gray scales, the first image includes a maximum gray scale area, and the second image includes a minimum gray scale area.