2473 results about "Fresnel lens" patented technology

Light emitting diode systems disclosed include semiconductor diodes arranged in cooperation with electrical contacts, mounting provisions, and optical couplings; where the optical couplings include at least a Fresnel lens. A Fresnel lens is further coupled to additional optical elements such as a concave or ‘negative’ lens and still further to a reflector operating via principles of total internal reflection. Both the concave lens and the reflector are aspherical in preferred versions. A cover element of single piece plastic may be formed in a molding process whereby all three of these optical elements, i.e. the Fresnel lens, the negative lens and the reflector, are formed into the single plastic piece. Further, the plastic piece may be arranged to also accommodate auxiliary systems such as alignment indexing and fastening means as well as interlocking peripheral configurations.

A head up display system for a vehicle that includes a compact image source for projecting an image. The compact image source may be foldable up toward or into a cockpit ceiling of the vehicle, be positioned within a dashboard of the vehicle, or located at another suitable position. A combiner reflects the projected image with optical power toward an observer for observation. The combiner is positioned so that the observer, in a line of sight, may see a visual exterior view of an outside scene through the combiner and the projected image in the combiner. In a preferred embodiment, the image source includes an illumination system that includes a high power light emitting diode (LED) array assembly. A Fresnel lens array is operatively associated with the LED array assembly for receiving light produced by the LED and providing a nearly collimated light output. A spatial light modulator receives the nearly collimated light output. The preferred combiner is a meniscus combiner that includes a meniscus lens; a multi-layer dichroic coating formed on a first surface of the meniscus lens; and, an anti-reflection coating formed on a second, opposite surface of the meniscus lens. The meniscus combiner preferably utilizes a non-symmetric aspheric meniscus lens.

A planar light source, Fresnel lens sheet, and louver are disposed in the stated order in a light source apparatus. The Fresnel lens sheet deflects and focuses in one dimension light that has entered from the planar light source. The louver is disposed in the optical path of the light emitted from the Fresnel lens sheet, and the directivity of the light can be increased by restricting the traveling direction of the light to the focal direction of the Fresnel lens sheet. The light utilization ratio can thereby be increased, the directivity of planarly emitted light can be increased, and the brightness can be made uniform at the point of observation.

This specification discloses an illuminating apparatus having a light source and an optical unit disposed forwardly on the object side of the light source, the optical unit being provided with an incidence surface on which light from the light source is incident, a light emergence surface provided with a Fresnel lens, and a side reflecting surface for totally reflecting the light incident on the incidence surface toward the Fresnel lens, wherein the light totally reflected by the side reflecting surface is refracted by the Fresnel lens and efficiently irradiates the object.

A light source includes a housing, an LED array of individual LED elements mounted in the housing, and a controller mounted in the housing and coupled to the LED array. The controller sequentially, intermittently pulses the LED elements of the LED array. The controller over drives the LED elements of the LED array with a current in excess of several times the continuous forward rating for the individual LED elements. The housing is a substantially closed, waterproof, tubular member and may include a power source in the housing. The light source may form a portable light source. The light source may include a fiber optic bundle coupling in the housing and a fresnel lens between the LED array and the fiber optic bundle coupling.

A Concentrating Photovoltaics (CPV) module includes a metal frame, a plurality of Fresnel lenses, a secondary reflective or refractive concentrator, multi-junction solar cells with up to 40% efficiency and a novel heat spreading material. The Fresnel lenses and the secondary concentrator focus the sun over 500 times to maximize the amount of photons collected by the solar cells and converted to electricity. A newly designed soft board material provides coefficient of thermal expansion (CTE) matched carrier for the solar cells and an efficient electrical connectivity method. The carrier board is attached to a specially formulated heat spreader made of graphite. At 40% the weight of aluminum and 18% the weight of copper, this specially formulated material offers thermal heat conductivity that is superior to copper. The combination of the above creates CPV modules with the highest efficiency and lowest cost per Watt.

A liquid crystal diffraction lens element and an optical head device, which can switch focal lengths of both of outgoing light and returning light by a single element, are provided.

The liquid crystal lens element comprises transparent substrates 1a, 1b, a liquid crystal 4 sandwiched between the transparent substrates 1a, 1b, transparent electrodes 2a, 2b, birefringent Fresnel lens members 3a, 3b each having a Fresnel lens shape and made of a birefringent material, and a seal 5, wherein the extraordinary refractive index direction A of the birefringent Fresnel lens member 3a and the extraordinary refractive index direction B of the birefringent Fresnel lens member 3b are perpendicular to each other, and the alignment direction of the liquid crystal 4 at the interface between the liquid crystal 4 and the transparent substrate 1a is perpendicular to the alignment direction of the liquid crystal 4 at the interface between the liquid crystal 4 and the transparent substrate 1b.

A linear illumination unit (30) has a line of unlensed LEDs (31) which emit light spreading out. The light is focused into a line by a Fresnel lens (33) which allows spread and mixing of light in the linear direction and limits spread in the ortliogonal direction. A Fresnel lens is particularly effective for this purpose. The housings 34 have slots 36 to help control light spread, and the housings are open-ended to allow spread of light in the linear direction beyond the confines of the, geometry of the units. Thus, units (30) may be interconnected to provide seamless linear light in a modular manner.

An ultraviolet sterilizer for use during surgery is mounted in a base cabinet. The UV light source can be a laser, or an LED. An optical frequency multiplier can be used that outputs UV of less than 280 nm, or greater than 320 nm, to avoid burning the patient. A visible LED aiming light directs the UV light toward the surgery. A crosshair image can be projected to position the light.

One lamp has a housing, a cavity, a handle, and an ocular plate to pass the UV and the aiming light. An articulated arm allows selective positioning of the lamp. Another lamp has a stylus, a handle, and a tip small enough for easy insertion into a small incision for arthroscopy. A fiber optic cable connects the UV and the aiming light to the lamp. Lenses or filters can be used with the fiber optic cable.

An electronic power supply and a CPU connect to the UV and the aiming light sources. A keyboard inputs commands to the CPU. A sensor provides feedback.

Another UV sterilizer is mounted on a ceiling of the operating room. A lamp has a housing with a cavity. Either a curved or a flat substrate is mounted in the cavity. Solid state UV elements are arrayed on the substrate, along with visible LEDs for aiming. Either a curved or a flat mirror is disposed behind the substrate. An ocular plate passes the UV and the aiming light, and protects the elements from damage. The ocular plate is a diffuser, a filter, or a fresnel lens.

Using inhomogeneous sized liquid crystal (LC) droplets for lens and prisms. For forming a positive lens, the LC droplet size can gradually increase from the center to the side edges. For forming a negative lens, the LC droplet size can gradually decrease from the center to the side edges. The lens can be created by Ultra Violet light exposure to patterns. The lens can be tuned by applying voltage to the droplets. The inhomogeneous droplets can also be used in Fresnel lens and prisms. Applications of the invention can be used for eyeglasses, arrays, camera type zoom lenses and beam steering applications.

A reflective illumination device is disclosed, which is comprised of a light-guiding screen with light reflecting ability and at least a directional light source; wherein the light-guiding screen includes a reflecting surface having a semi-Fresnel lens structure arranged thereon. The semi-Fresnel lens structure, being designed basing on the principle of Fresnel lens, is the equivalent of a parabolic mirror that has spiral cut ridges for focusing light to a focal point, whereas the profile of the ridges can be a planar surface, a curved surface or the combination thereof. By arranging the reflecting surface with semi-Fresnel lens structure at the bottom of the light-guiding screen and each light source at a circumferential side wall of the light-guiding screen, the light beams emitting from each light source can be reflected out of the light-guiding screen by a specific angle as the direction of the light beams is adjusted to pour on the semi-Fresnel lens structure by a specific angle matching the configuration of the same.

A novel, high-efficiency, extremely light-weight, inflatable refractive solar concentrator for space power is described. It consists of a flexible Fresnel lens, flexible sides, and a back surface, together enclosing a volume of space which can be filled with low pressure gas to deploy the concentrator on orbit. The back surface supports the energy receiver/converter located in the focal region of the Fresnel lens. The back surface can also serve as the waste heat radiator. Prior to deployment, the deflated flexible lens and sides are folded against the back surface to form a flat, low-volume package for efficient launch into space. The inflatable concentrator can be configured to provide either a line focus or a point focus of sunlight. The new inflatable concentrator approach will provide significant advantages over the prior art in two different space power areas: photovoltaic concentrator arrays and high-temperature solar thermal conversion systems. Photovoltaic concentrator arrays using the new inflatable lens will be much lighter than prior space concentrator arrays. In addition, for photovoltaic concentrator arrays, the new inflatable lens will eliminate the need for a fragile glass superstrate to support the lens, substantially improving robustness of the lens. Solar thermal concentrator arrays using the new inflatable lens will be much lighter than prior art space concentrators which used parabolic mirrors. In addition, for solar thermal applications in space, the new inflatable lens will eliminate the need for high surface accuracy, which has been a significant problem for prior art concentrators.

The present invention provides an imaging lens device, which has a widely extended focusing range and exhibits good resolution over the entire focusing range. The imaging lens device comprises a liquid crystal lens for focusing an object at a prescribed distance, comprising a liquid crystal layer, a first transparent substrate disposed adjacent to one surface of the liquid crystal layer and having a first electrode and having Fresnel lens surface formed on the boundary with the liquid crystal layer, a second transparent substrate disposed adjacent to the other surface of the liquid crystal layer and having a second electrode; a controller for changing the refractive index of the liquid crystal layer for extraordinary ray by changing electric voltage applied between the first electrode and the second electrode; and an imaging element for taking an image of the object. The liquid crystal lens functions as a diffractive optical element for an extraordinary ray when the liquid crystal layer has a prescribed refractive index for an extraordinary ray incident upon the liquid crystal layer.

A high power LED lamp and method for retrofitting conventional traffic signal lamps. The LED lamp includes a housing, a power supply disposed in the housing, a plurality of LEDs mounted to a substantially planar mounting surface in the housing and electrically connected to the power supply for producing diverging light, and a threaded electrical connector extending from the housing. The method includes replacing a conventional incandescent light bulb with the LED lamp, and installing a Fresnel lens inside the traffic signal lamp that collimates and just fills and illuminates the outer lens of the traffic signal lamp.

A lighting device having a plurality of high flux LEDs mounted on a heat sink and surrounded by a diffuser and a power supply that provides independent power to individual sets of the LEDs. The heat sink serves to transfer heat from the LEDs to the outside environment. In one embodiment the lighting device is positioned within a fresnel lens to produce a distribution of light.

Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a Fresnel lens system (115) supported by the frame (107). The HMD (100) can employ a reflective optical surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107), with the Fresnel lens system (115) being located between the image display system (110) and the reflective optical surface (120). The Fresnel lens system (115) can include at least one curved Fresnel lens element (820). Fresnel lens elements (30) for use in HMDs are also disclosed which have facets (31) separated by edges (32) which lie along radial lines (33) which during use of the HMD pass through a center of rotation (34) of a nominal user's eye (35) or through the center of the eye's lens (36) or are normal to the surface of the eye's cornea.