A planar illumination device of an embodiment includes a substrate, a first linear Fresnel lens, and a second linear Fresnel lens. The substrate includes a plurality of light sources disposed two-dimensionally in a grid pattern. The first linear Fresnel lens is disposed at an emission side of the plurality of light sources and formed with a groove constituting a concave-convex surface of the lens and extending in one direction. The second linear Fresnel lens is disposed at an emission side of the first linear Fresnel lens and formed with a groove constituting the concave-convex surface of the lens and extending in a direction orthogonal to the one direction.

A structure includes a support 10, a first optical filter layer 24 provided on the support, a light scattering layer 50 provided on the light path of the first optical filter layer 24, and a second optical filter layer 21, 22, 23, 25, and 26 provided on the support 10, on a different region from the region where the first optical filter layer is provided, and the light scattering layer 50 is not provided on the light path of the second optical filter layer.

An optical composite sheet is disclosed. In the optical composite sheet, optical functional elements such as a prism sheet and a light diffusion layer are combined, and a light absorbing layer that selectively absorbs light of a specific wavelength band is inserted, so that the optical performance and color gamut can be enhanced as compared with the prior art. In particular, the color transmittance of the optical composite sheet with respect to wavelength measured for each viewing angle satisfies a specific relationship, whereby it is possible to effectively reduce the color deviation with respect to the viewing angle.

A homogenizing module and a projection apparatus are provided. The homogenizing module is configured to homogenize a beam and includes an anisotropic diffuser and a homogenizer. The anisotropic diffuser is located on a transmission path of the beam. The beam has a first divergence angle in a first direction and a second divergence angle in a second direction after passing through the anisotropic diffuser. The first divergence angle is greater than the second divergence angle. The homogenizer is located on a transmission path of the beam from the anisotropic diffuser, and the homogenizer includes multiple optical elements. The size of any of the multiple optical elements in the first direction is greater than the size thereof in the second direction. The first direction is perpendicular to the second direction.

An artifact caused by secondary reflection is reduced. An imaging device according to an embodiment includes: a diffuser (110) that converts incident light into scattered light whose diameter is expanded in accordance with a propagation distance and outputs the scattered light; and a light receiver (132) that converts light diffused by the diffuser into an electric signal.

A diffusion apparatus includes a diffuser, a substrate to which the diffuser is fixed, and a first lens that has a curved surface and a flat surface located on the side opposite the curved surface and is so fixed to the substrate as to face the diffuser. The substrate includes a first recess having a first bottom surface and a first side surface that rises from the first bottom surface and a second recess having a second bottom surface connected to the first side surface and a second side surface that rises from the second bottom surface. The first lens is so disposed in the second recess that the flat surface is in contact with the second bottom surface. The diffuser is fixed to the first bottom surface.

A display device comprises a plurality of light sources, a luminance equalizer sheet and a display. The light sources include a plurality of first light sources arranged in an array on an arrangement region and a plurality of second light sources arranged at corner portions of the arrangement region, respectively. The luminance equalizer sheet is arranged opposite the light sources to equalize luminance, the luminance equalizer sheet including first portions that face the first light sources, respectively, and second portions that face the second light sources, respectively, the second portions being different from the first portions. The display is arranged opposite the luminance equalizer sheet and disposed on an opposite side of the luminance equalizer sheet relative to the light sources. The second portions of the luminance equalizer sheet form corner low transmittance areas with lower light transmittance than a portion of the luminance equalizer sheet other than the first portions and the second portions.

The present disclosure provides a light homogenizing film, a backlight module and a display device. The light homogenizing film includes a substrate film layer on which a plurality of light homogenizing structures are arranged in an array. The light homogenizing structure includes: a first recess in a regular pyramid shape positioned on a light incident surface of the substrate film layer, and a second recess in a regular pyramid shape positioned on a light emitting surface of the substrate film layer. On a plane where a main body of the substrate film layer is located, an orthographic projection of the second recess completely covers an orthographic projection of the first recess, and the orthographic projections of the first and second recesses are regular polygons which have overlapped centers, the same number of sides and the same orientation.

A light filter (100) includes at least one layer of binder matrix (110) and a multitude of transparent crystals (120). The multitude of transparent crystals (120) are irregularly and laterally dispersed in the at least one layer of binder matrix (110), such that light passing through the light filter (100) is separated into different wavelengths and polarized into different orientations.

According to at least one aspect, the present disclosure provides a head-up display device comprising: a housing having a receiving space therein; a display unit disposed over the housing; a light source unit disposed so that a main optical axis is not directed at the display unit; a first reflector reflecting at least some of light emitted from the light source unit towards the display unit; and a diffuser disposed on an optical path of the light source unit reflected from the first reflector to uniformly make light.