An optical focus control and method use rotations of a set of shift-invariant optical elements (Risley elements) that are fairly tolerant to optical misalignments and wobble in control systems. The Risley elements can be Risley prisms, Risley gratings, or photonic crystals that impart a fixed angular offset. Aligning at least one pair of Risley elements that are individually rotated can achieve an angular correct to light received off-axis for better detection by an optical detector, improving focus control.

The embodiments of the present disclosure provide a display panel. The display panel includes a first substrate, a second substrate disposed opposite to the first substrate, and a liquid crystal layer between the first substrate and the second substrate, a plurality of first electrodes disposed on a side, close to the second substrate, of the first substrate and spaced apart at intervals, a first dielectric layer for planarizing the plurality of first electrodes, a second dielectric layer disposed on a side, close to the liquid crystal layer, of the first dielectric layer, a light shielding portion disposed on the side, close to the liquid crystal layer, of the second substrate, and a control circuit configured to apply a voltage between the first electrode and the second electrode so that the liquid crystal layer is in a first state or a second state.

A backlight module is provided. The backlight module includes a substrate; a plurality of light-emitting elements, disposed on the substrate along a first direction and a second direction; and at least one optical film, including: a first surface, having a plurality of cone structures, top points of the cone structures being arranged to form a plurality of first ridges. In addition, an angle is between the first ridge and the first direction; and a second surface, corresponding to the first surface and toward the substrate, the plurality of light-emitting elements being between the substrate and the second surface.

A surface light source includes: a light guide plate having an upper surface and a lower surface located opposite the upper surface, and including at least one through hole extending from the upper surface to the lower surface; a wiring substrate located on a lower surface side of the light guide plate and including a wiring layer; and at least one light source including a light-emitting element electrically connected to the wiring layer of the wiring substrate. The light source is located inside the through hole. The upper surface of the light guide plate has a first region including a plurality of depressed portions.

A light emitting device includes a printed circuit board (PCB) substrate, a first ink layer covering the PCB substrate, the first ink layer having a first refractive index, light emitters on the first ink layer, and a second ink layer on the first ink layer and spaced apart from the light emitters, the second ink layer having a second refractive index different from the first refractive index.

A planar light source includes a mounting substrate, a plurality of light sources, a partition member, a frame body, a wavelength conversion member, and a light diffusion plate. The light sources are arranged two-dimensionally on the mounting substrate in a plan view. The partition member includes a wall portion surrounding each of the light sources except for outermost ones of the light sources in the plan view. The wall portions are located inward of the outermost ones of the light sources. The frame body has a bottom portion and a lateral wall surrounding the mounting substrate. The wavelength conversion member is disposed on the lateral wall of the frame body. The light diffusion plate is disposed above the plurality of light sources and the wavelength conversion member.

An illumination apparatus comprises a plurality of LEDs aligned to an array of directional optical elements wherein the LEDs are substantially at the input aperture of respective optical elements. An electrode array is formed on the array of optical elements to provide at least a first electrical connection to the array of LED elements. Advantageously such an arrangement provides low cost and high efficiency from the directional LED array.

A light guide plate including a substrate; a first refractive index layer; a second refractive index layer stacked on the first refractive index layer, and a reflective layer disposed on a surface of the substrate opposite to the first refractive index layer, wherein the first refractive index layer is a structure of a plurality of prisms distributed on an emergence surface of the substrate, forming prism-structured netted dots. Through disposing the prism-structured netted dots, the reflective layer, and the second refractive index layer on the light guide plate substrate, and using refraction and reflection of each layer to realize adjustment of emergence angle, a function of an independent diffuser, prism, and reflector is realized. The light guide plate is used as CF or TFT substrate to manufacture a liquid crystal display, and a backlight module is integrated into a liquid crystal panel, decreasing a thickness of a liquid crystal module.

A display device includes a backlight and a display panel on the backlight. The backlight includes a light source to provide a first light, and an optical wavelength converter to receive the first light and emits a second light. The optical wavelength converter includes a light emitting part having a plurality of excitation light emitting bodies to be excited by receiving the first light, and thereby emit the second light, and a light absorbing part including a plurality of absorbers provided on the light emitting part to receive the second light and absorb a portion of the second light having a wavelength of about 550 nm to about 650 nm.

A display device including a display panel and a backlight module is provided. The backlight module is correspondingly disposed below the display panel and includes light-emitting elements providing light beams and disposed on a circuit board, lens units each being disposed on a corresponding light-emitting element and having a concave inside surface covering the corresponding light-emitting element and a convex outside surface covering the concave inside surface, and an inverse prism sheet disposed between the lens units and the display panel, and the inverse prism sheet having inverse prisms with a vertex corner. At least a portion of the light beams emitted from the convex outside surface each has a predetermined light-emitting angle θ.sub.o larger than 30 degrees and less than 90 degrees. The backlight module has a height of cavity D being a distance between the vertex corner and the circuit board, and 10 μm≦D<30 mm.