Abstract: Lighting apparatus for an image-gathering device, includes a light frame supporting a plurality of light emitting diode lamps configured to emit light at a tungsten balanced color temperature, and a support member that defines a filter tray aperture to accommodate a filter tray. The light frame defines a circular aperture to enable the light frame to be located around the barrel of a camera lens, and the filter tray aperture is visible within said circular aperture of said light frame. A manually adjustable filter clamp is provided for holding a filter tray in place once located with respect to the filter tray aperture. Lighting apparatus arranged to accommodate a plurality of filter trays.

Abstract: An LED projector lamp includes, in succession along an optical axis thereof, a lamp holder, an LED light source, a light-mixing lens and a cover lens. The LED light source has LED chips arranged inside the lamp holder around the optical axis for emitting different wavelengths of light. The light-mixing lens has a structural surface with parallel lines of protrusions facing the cover lens such that such that the emitted light rays of the LED chips that pass through the structural surface are scattered at least one time and then pass through the cover lens. As a result, the emitted different wavelengths of light can be well mixed before going to the outside of the LED projector lamp.

Abstract: A lighting device generally comprises a housing, including a base portion and a side wall, which defines an interior cavity with an open end; a plurality of light-emitting diodes positioned within said interior cavity, each light-emitting diode emitting a light of a first hue; a plurality of bulbs, each said bulb being associated with and fitting over a respective light-emitting diode, each said bulb converting the light of the first hue emitted from the light-emitting diode into a light of a desired hue, which is then emitted from said bulb; and a front panel positioned at the open end of the housing and receiving light from the plurality of bulbs for illuminating the front panel.

Abstract: The present invention is directed to a collar for a multi-color light source that is able to convey not only color but also spatial information to a user to permit the colorblind user to distinguish between the different settings of the light source.

Abstract: A lighting system includes a first light source emitting first light rays; a second light source emitting second light rays, a first lens side which refracts the first and second light rays and collimates the refracted light rays; a second lens side which includes a plurality of first lenticules and refracts the first and second light rays; and a third lens side which includes a plurality of second lenticules and refracts the first and second light rays refracted by the second lens side.

Abstract: Lighting packages are described for light emitting diode (LED) lighting solutions having a wide variety of applications which seek to balance criteria such as heat dissipation, brightness, and color uniformity. The present approach includes a backing of thermally conductive material and two or more arrays of LEDs attached to a printed circuit board (PCB). The PCB is attached to the top surface of the backing and the two or more arrays of LEDs are separated by a selected distance to balance heat dissipation and color uniformity of the LEDs.

Abstract: A lighting apparatus (10) comprises a light engine (12) producing ultra violet radiation. An enclosure (14) surrounds a radiation generating area of the light engine (12) to encompass the radiation. At least one wall (28) of the enclosure (14) is substantially reflective of the ultraviolet radiation. The enclosure (14) includes a replaceable top portion (30) which includes a phosphor portion (32). The phosphor portion (32) is spaced from the radiation generating area of the light engine (12) by a height of the enclosure (14).

Abstract: The present invention provides a lighting device package that is configured to enable degassing of the lighting device package. The lighting device package comprises a substrate upon which is operatively mounted one or more light-emitting elements and a retaining structure which is coupled to the substrate and configured to circumscribe the one or more light-emitting elements. In addition, the lighting device package includes an optically transmissive element, wherein two or more supports are configured to provide a separation between the optically transmissive element and the substrate or retaining structure. The volume defined by the substrate, retaining structure and the optically transmissive element, is partially or completely filled with an encapsulation material, thereby forming the lighting device package.

Abstract: The LED-radiance source is a suitable replacement of lamp-based integrating sphere sources where they are used as stable and uniform radiance sources. The LED-based radiance source includes an array of LEDs having substantially similar radiance output wavelengths and a radiation detector such as a photodiode that detects and monitors radiation directed from the LEDs. Temperature of the LEDs can be controlled by feedback from a photodiode, thereby allowing for control and stabilization of temperature-dependent radiation output.

Abstract: A system provides white light having a selectable spectral characteristic (e.g. a selectable color temperature) using an optical integrating cavity to combine energy of different wavelengths from different sources with white light. The cavity has a diffusely reflective interior surface and an aperture for allowing emission of combined light. Control of the intensity of emission of the sources sets the amount of primary color light of each wavelength added to the substantially white input light output and thus determines a spectral characteristic of the white light output through the aperture. A variety of different elements may optically process the combined light output, such a deflector, a variable iris, a lens, a variable focusing lens system, a collimator, a holographic diffuser and combinations thereof.

Abstract: An electronic visual display system with an integrated general lighting system including an electronic visual display having a housing and one or more lighting devices integrated therewith to provide light to one or more spaces external to the electronic visual display housing. The lighting devices have an independent on and off state which allows for the lighting devices to be in the on state independent of the on and off state of the electronic visual display. The lighting devices provide a relatively constant and user selectable color and level of light output.

Abstract: An imaging system comprises a light source module configured to generate a combination beam, a controller configured to control the light source module, an image-capturing module configured to capture the reflected beam by a sample. The light source module comprises a plurality of light-emitting devices configured to emit lights of different wavelengths, and the controller is configured to drive the light-emitting devices to emit the lights to form the combination beam consisting of at least two lights of different wavelengths. An imaging method comprises the steps of forming a first combination beam consisting essentially of at least two lights of different wavelengths, capturing the reflected first combination beam by a sample to have a first image, forming a second combination beam consisting of at least two lights of different wavelengths and capturing the reflected second combination beam by the sample to have a second image.

Abstract: A display device includes an ultraviolet light source, a color light source, and a filter selectively hit by their lights. The filter has a first area part for displaying the first display contents excluding an overlapped parts when the ultraviolet light is emitted, a second area part for the second display contents excluding the overlapped parts when the color light is emitted, and a third display part for displaying the overlapped parts when one of the ultraviolet and color light is emitted. The first area part blocks the color light and produces visible light when the ultraviolet light hits the first area part, the second area part allows the ultraviolet and color lights to pass therethrough, and the third area part allows the ultraviolet and color lights to pass therethrough and produces the visible light when the ultraviolet light hits the third area part.

Abstract: A lamp that allows a user to adjust parameters to control emitted white light, specifically quality, intensity and color temperature. Under such control, the lamp can match, complement, or augment ambient or available natural or artificial light. In specific embodiments, the lamp uses high power, high CRI, white LED sources; integral thermal management that also functions as LED structural support; integral optics (secondary lenses) with accommodation for diffusing elements; and manually responsive controls.

Abstract: An LED lamp includes a housing, at least one circuit board, several LED and two electric wires. The LED are mounted on a bottom face of the circuit board. The circuit board and the LED are all installed in the housing with the LED located at a bottom end of the housing. Two through holes are formed on a top end of the housing. The electric wires respectively passed through the through holes of the housing to electrically connect with the circuit board. The LED lamp is inbuilt with LED so that it is unnecessary to further install any LED bulb. The electric wires can be serially connected so that multiple LED lamps can be easily connected.

Abstract: Methods and apparatus for generating and modulating white light illumination conditions. Examples of applications in which such methods and apparatus may be implemented include retail environments (e.g., food, clothing, jewelry, paint, furniture, fabrics, etc.) or service environments (e.g., cosmetics, hair and beauty salons and spas, photography, etc.) where visible aspects of the products/services being offered are significant in attracting sales of the products/services. Other applications include theatre and cinema, medical and dental implementations, as well as vehicle-based (automotive) implementations. In another example, a personal grooming apparatus includes one or more light sources disposed in proximity to a mirror and configured to generate variable color light, including essentially white light, whose color temperature may be controlled by a user.

Abstract: A solid state light source having first and second component light sources and an interface circuit and a method for making the same are disclosed. The first and second component light sources emit light having first and second color points on different sides of the black body radiation curve. The first and second component light sources include LEDs that emit light of a first wavelength and a layer of a light converting material that converts a portion of that light to light of a second wavelength. The interface circuit powers the first and second component light sources such that the solid state light source has a color point that is closer to the black body radiation curve than either the first or second color points. A third component light source can be included to expand the range of white color temperatures that can be reached by the light source.

Abstract: A low profile backlighted display includes a translucent display piece having a viewable surface. A casing is configured expose at least a portion of the viewable surface. The display piece may have a perimeter, and the casing may conform generally to the perimeter of the display piece. An illumination cavity is configured within the casing and is behind the viewable surface of the display piece. A plurality of light emitting diodes (LEDs) are located within the illumination cavity. At least one of the LEDs may be configured to backlight the display piece, and one or more of the LEDs may be configured to emit essentially only non-visible light. A passive element may be configured to backlight the viewable surface when excited by non-visible light from the non-visible light LEDs. The plurality of LEDs and the passive element collectively provide an essentially uniform back light illumination of the viewable surface.

Abstract: There is provided a lighting device which emits light with an wall plug efficiency of at least 85 lumens per watt. The lighting device comprises at least one solid state light emitter, e.g., one or more light emitting diodes, and optionally further includes one or more luminescent material. In some embodiments, the output light is of a brightness of at least 300 lumens. In some embodiments, the output light has a CRI Ra of at least 90. Also, a method of lighting, comprising supplying electricity to a lighting device which emits light with a wall plug efficiency of at least 85 lumens per watt.

Abstract: Color displays superpose a two color image component with a monochrome image component to yield full color images. Each image component may be generated by controlling an array of light sources. In some embodiments the monochrome image component is provided by a backlight and the two color component is provided by an array of sub-pixels of two types.

Abstract: A method for improving color purity of a light source module is provided. The light source module includes a light source suitable for emitting color lights with different wavelengths and a transparent cover encapsulating the light source. In the method, a light filtering material is coated on or doped into the transparent cover to absorb part of the color lights with specific wavelengths. Besides, a light source module which adopts the method is provided.

Abstract: Disclosed herein are solid state illumination systems which provide improved color quality and/or color contrast. The systems provide total light having delta chroma values for each of the fifteen color samples of the color quality scale that are preselected to provide enhanced color contrast relative to an incandescent or blackbody light source, in accordance with specified values which depend on color temperature. Illumination systems provided herein may comprise one or more organic electroluminescent element, or they may comprise a plurality of inorganic light emitting diodes, wherein at least two inorganic light emitting diodes have different color emission bands. Methods for the manufacture of illumination systems having improved color quality and/or color contrast are also provided.

Abstract: A semiconductor radiation source, having at least two light sources which are fixed on a common base body and so light can be emitted gently over a total emission spectrum, the first light source having a short-wave, in particular from 400 to 430 nm emission spectrum, and the second light source having a longer-wave, in particular from approximately 450 to 480 nm emission spectrum. The first light source (16) is arranged in an optical axis (22) and the second light source (18) has at least two chips (24, 26, 28, 30) which are arranged in particular symmetrically with respect to one another and with respect to the optical axis (22) and in a manner surrounding the optical axis (22).

Abstract: A light engine has a light source front surface that emits non-collimated light. A collection lens collects the non-collimated light and provides incompletely collimated light. A collimating lens receives the incompletely collimated light and provides a collimated image. A non-orthogonal polarizing filter receives the collimated image and passes a polarized portion of the collimated image as a direct component of the polarized light engine image. The non-orthogonal polarizing filter reflects a recycled image back to the front surface. The non-orthogonal shape of the polarizing filter is selected according to the pattern of light on the light source front surface.

Abstract: An infrared projector for a vehicle using a semiconductor light-emitting element that prevents a lens from becoming reddish by a red light component generated with infrared rays includes: a semiconductor light-emitting element for generating infrared rays and a red light component; and a lens for irradiating in a forward direction the infrared rays and the red light component from said semiconductor light-emitting element. The infrared projector for a vehicle further includes a light source for generating white light and emitting the white light from the light source incident on the lens. Use of scattered light reduces the influence of a red light component passing through the lens.

Abstract: After the LEDs 2 (red LEDs (R), green LEDs (G) and blue LEDs (B), or white LEDs (W)) are mounted on the frame 3, without dicing the frame 3 for dividing the LEDs 2 into pieces, the tie bar is punched off to form an electric circuit. Thus, the RGB three primary color LED light source 1A or the white LED light source 1B that emits light in the state of the frame 3 can be manufactured.

Abstract: A desired color of illumination of a subject is achieved by determining settings for color inputs and applying those setting to one or more systems that generate and mix colors of light, so as to provide combined light of the desired character. In the examples of appropriate systems, an optical integrating cavity diffusely reflects light of three or more colors, and combined light emerging from an aperture of the cavity illuminates the subject. System settings for amounts of the different colors of the input lights are easily recorded for reuse or for transfer and use in other systems.

Abstract: Three light sources are provided as a light source. A first light source emits a light in red, a second light source emits a light in green, and a third light source emits a light in blue. Each light source is a light source in which a plurality of LEDs (light-emitting diodes) are arranged in the same plane surface. The first light source, the second light source, and the third light source are arranged on the same plane surface. Furthermore, lines connecting the first light source, the second light source, and the third light source form a triangle. Light fluxes (primary optical axes) of each light source are parallel with each other. The first light source, the second light source, and the third light source are arranged on one piece of a cooling plate.

Abstract: A light emitting device is produced using one or more light emitting diodes within a light mixing cavity formed by surrounding sidewalls. The light emitting device includes a light adjustment member that is movable to alter the shape or color of the light produced by the light emitting device. For example, the light adjustment member may alter the exposure of the wavelength converting area to the light emitted that is emitted by the light emitting diode in the light mixing cavity. Alternatively, the height of a lens may be adjusted to change the width of the beam produced. Alternatively, a movable substrate with areas of different wavelength converting materials may adjustably cover the output port of the light mixing cavity to alter the color point of the light produced.

Abstract: The invention provides an image projection system including a first light source and a second light source. Light from the first light source is limited to a finite number of limited wavelength intervals. An imaging device is adapted for modulating light from the first and second light sources. A beam combiner is provided to combine light from the light sources and direct the combined light to the imaging device. Modulated light from the imaging device is directed to a lens.

Abstract: A lighting assembly comprises a light fixture. The light fixture includes a trim formed by a stamping or die casting process. The trim has thermally conductive properties and includes a flange around a perimeter of the trim. The light fixture includes a light source mounted to a central portion of a front surface of the trim, and a heatsink formed by an extrusion or die casting process. The heatsink has thermally conductive properties and is mounted to a back surface of the trim. The light fixture includes an attachment mechanism connected to the light fixture. A recessed can housing mounted to a surface may be provided. The light fixture may be mounted to the recessed can housing by inserting the heatsink into the recessed can housing and engaging the attachment mechanism to an interior portion of the recessed can housing to brace the flange against the surface.

Abstract: A recessed light fixture includes an LED module, which includes a single LED package that is configured to generate all light emitted by the recessed light fixture. For example, the LED package can include multiple LEDs mounted to a common substrate. The LED package can be coupled to a heat sink for dissipating heat from the LEDs. The heat sink can include a core member from which fins extend. Each fin can include one or more straight and/or curved portions. A reflector housing may be coupled to the heat sink and configured to receive a reflector. The reflector can have any geometry, such as a bell-shaped geometry including two radii of curvature that join together at an inflection point. An optic coupler can be coupled to the reflector housing and configured to cover electrical connections at the substrate and to guide light emitted by the LED package.

Abstract: Described herein are display devices that provide projection-type video output and use redundant sets of lasers to generate light. The laser set produces a desired amount of light, e.g., for a primary color. A redundant laser set includes more lasers than that needed to produce the desired amount of light. For example, a set of six lasers may only need five lasers to generate and emit a desired amount of light. The sixth laser allows failure of one laser in the set to not compromise operability of the entire set—and the display device. In addition, extra lasers in a laser set also allows the lasers to be cycled for heat purposes and to extend longevity of individual lasers in the set.

Abstract: A vehicle display includes two colored light sources that are operatively connected to a circuit board. Each of the two colored light sources emits a colored light that mixes to form a desired color of display light that illuminates a vehicle graphic. The desired color of display light is within a predetermined color tolerance. The vehicle display achieves a small size without incurring added expenses associated with using more than two light sources.

Abstract: A desired color of illumination of a subject is achieved by determining settings for color inputs and applying those setting to one or more systems that generate and mix colors of light, so as to provide combined light of the desired character. In the examples of appropriate systems, an optical integrating cavity diffusely reflects light of three or more colors, and combined light emerging from an aperture of the cavity illuminates the subject. System settings for amounts of the different colors of the input lights are easily recorded for reuse or for transfer and use in other systems.

Abstract: A luminaire suitable for color mixing of light originating from lamps having different color properties has reflectors configured to provide an equal ratio of partial illuminance for each of the color properties at each position of a translucent element, e.g. a diffuser. This provides a uniform color mixing and/or the possibility of adjusting the color properties of the luminaire merely by adjusting the brightness of one or more of the lamps. The reflectors may include top reflectors, side reflectors and/or shielding reflectors positioned between the lamps and the exit window. The shielding reflectors may be configured to partly reflect and partly transmit light.

Abstract: The invention relates to an illuminating device for microscopes, wherein the light source has, in particular, a white light illumination having total daylight spectrum and/or an excitation light source for fluorescent colors. The inventive illuminating device for a microscope consists of surface or spatially arranged light sources, which are connected to a control unit for generating any desired illuminating patterns and illuminating spectrums, and an illuminating optic to image these illuminating patterns on the object to be examined. The light sources consist of LEDs (11) which excite at least one luminescence color (14) which is adapted to the wavelength which is emitted by the LEDs (11). The LEDs (11) are arranged concentrically to the optical axis of the illuminating device, preferably, in or in the vicinity of the aperture diaphragm plane.

Abstract: Disclosed examples of lighting systems having at least three light sources of different colors may be controlled by validating input settings representing chromaticity and/or intensity of desired light to be generated by determining if the respective lighting system is capable of generating the desired light. This may involve comparing the chromaticity and/or intensity to a three-dimensional gamut representing chromaticity and associated intensities that the lighting system is capable of generating. The top contour of the gamut represents the maximum intensities for every chromaticity which the lighting system is capable of generating. Specifically the top contour is defined by points representing the maximum attainable intensities that each light source is capable of generating and the maximum intensity attainable by the lighting system.

Abstract: A flickerless light source comprising a transparent or semitransparent diffuser, at least two lightpipes with patterned surfaces inside the diffuser, a single sided LED light source attached to each end of the diffuser, and a dual sided LED light source connecting the lightpipes together is disclosed. The patterned surface of the lightpipes diffuse or reflect light emitted by the single and dual LED light sources and through the lightpipes to provide a light with uniform brightness and intensity. The lightpipes are coated with a thin layer of visible-light transparent material which is doped with organic dye molecules. The organic dye has strong ultraviolet light absorption characteristics. By changing the doping concentration of the dye molecules the coating can become totally opaque or semi-transparent to certain wavelengths and selective wavelength conversion is obtained. In this way light color, brightness, and intensity can be varied or controlled.

Abstract: A method and apparatus of lighting a marine habitat for growth utilizing an LED light system. The light system includes an LED light source, a power supply for such light source and a controller for controlling the activation status and the intensity of the LED light source.

Abstract: An illumination apparatus includes a heat-conductive tubular housing. A lighting device includes: a heat dissipating plate positioned in the housing and disposed adjacent to an open front end of the housing; lighting units, each having a light emitting diode mounted on a circuit board in thermal contact with the heat dissipating plate, and a condensing member mounted on the circuit board and disposed around the light emitting diode; and a driving unit disposed fixedly in the housing, connected electrically to the circuit board, and coupled electrically to an external power source for activating the light emitting diodes. A seal washer is disposed among and abuts against the housing, a transparent plate in front of the lighting units, and an annular cap mounted on the front end of the housing, so as to establish a liquid-tight seal thereamong.

Abstract: The first and second light-emitting regions are provided on the light source. When the first optical fiber having the first core diameter is connected, the light emitted from the first light-emitting region enters the first core. When the second optical fiber having a greater core diameter than the first core diameter is connected, the lights emitted from the first and second light-emitting regions enter the second core. It is thus possible to connect the optical transmission device with multiple optical fibers having different core diameters. It is thus possible to provide the optical transmission device and the communication device, which are low in cost and high in convenience.

Abstract: A solar simulator combines mercury lamps and halogen lamps, to improve upon conventional solar simulators using halogen and infrared lamps which cannot recreate an environment close to that under real sunlight, and upon solar simulators using expensive and fragile metal halide lamps and arc xenon lamps. An environment recreation laboratory for solar simulation includes a lamp bank mounted at an upper portion thereof and including a plurality of halogen lamps, halogen filter lamps being halogen lamps provided with an infrared filter, respectively, and mercury lamps. A temperature control unit includes a cooling unit that discharges air to cool the lamp bank, and an air conditioner that distributes the air discharged by the cooling unit. An electrical panel controls operations of the lamp bank and the temperature control unit, such that an environment within the environment recreation laboratory may very closely simulate the environment under real sunlight.

Abstract: A clip type light is detachably attached to a cap visor so as to ensure the user's field of vision. Two clips are integrally formed with both sides of a front section of a lamp body such that the two clips can be fixedly coupled with a front section of the cap visor regardless of the curved configuration of the visor. The clip type light can be easily attached to or detached from the cap visor without causing damage to the visor, and a switch for operating an electric lamp and an ultrasonic wave generator is provided at a lower portion of the lamp body in such a manner that the user can easily activate the electric lamp and the ultrasonic wave generator while wearing the cap equipped with the clip type light. A solar cell may also be provided to power the lamp and wave generator.

Abstract: A visualization device is described. The visualization device includes a body. The body includes a cavity configured to receive one or more components. One or more activating light sources may be positioned in the cavity of the body and are configured to produce activating light. One or more white light sources may be positioned opposite to the activating light source in the cavity of the body and are configured to produce white light. The activating light sources and the white light sources are both coupled to one or more power sources. Methods of detecting leaks using the visualization device are also described.

Abstract: A method for creating an improved signal light is disclosed. For example, the improved signal light includes a housing, one or more first type of light emitting diodes (LEDs) emitting a light energy having a first dominant wavelength deployed in the housing, one or more second type of LEDs emitting a light energy having a second dominant wavelength deployed in the housing, a filter and a mixer. The filter may filter the light energy of the one or more second type of LEDs such that only a third dominant wavelength passes from the one or more second type of LEDs. The mixer may mix the light energy having the first dominant wavelength and the filtered light energy having the third dominant wavelength to form a light energy having a desired fourth dominant wavelength.

Abstract: A white light emitting device including: a blue LE chip having a dominant wavelength of 430 to 455 nm; a red phosphor disposed around the blue light emitting diode chip, the red phosphor excited by the blue light emitting diode chip to emit red light; and a green phosphor disposed around the blue light emitting diode chip, the green phosphor excited by the blue LED chip to emit green light, wherein the red light emitted from the red phosphor has a color coordinate falling within a space defined by four coordinate points (0.5448, 0.4544), (0.7079, 0.2920), (0.6427, 0.2905) and (0.4794, 0.4633) based on the CIE 1931 chromaticity diagram, the green light emitted from the green phosphor has a color coordinate falling within a space defined by four coordinate points (0.1270, 0.8037), (0.4117, 0.5861), (0.4197, 0.5316) and (0.2555, 0.

Abstract: An illumination source includes at least one light emitting diode, e.g., in array of LEDs that produce short wavelength light. One or more wavelength converting elements, such as phosphor elements, convert at least a portion of the short wavelength light from the LED(s) to longer wavelengths, such as Red and Green. A dichroic element positioned between the LED(s) and the wavelength converting element(s) transmits the light from the LED(s) and reflects the longer wavelengths from the wavelength converting element(s). A color selection panel selects the colors of light to be produced by the illumination device and to be recycled for another opportunity to be converted by the wavelength converting element(s) or to be reflected by the dichroic element. The color selection panel may operate in one or both of the spatial domain and the temporal domain.

Abstract: An optical manifold for efficiently combining a plurality of blue LED outputs to illuminate a phosphor for a single, substantially homogeneous output, in a small, cost-effective package. Embodiments are disclosed that use a single or multiple LEDs and a remote phosphor, and an intermediate wavelength-selective filter arranged so that backscattered photoluminescence is recycled to boost the luminance and flux of the output aperture. A further aperture mask is used to boost phosphor luminance with only modest loss of luminosity. Alternative non-recycling embodiments provide blue and yellow light in collimated beams, either separately or combined into white.

Abstract: The present invention discloses a backlight structure having embedded light emitting diodes (LEDs) and a fabrication method thereof. The backlight structure comprises a PCB having a plurality of arc-shaped pits and necessary circuitry implemented thereon; a nanometer-thick gold layer sputtered on surfaces of said PCB and said plurality of arc-shaped pits; and an LED die embedded in each one of said plurality of arc-shaped pits, wherein said LED die is fused and fixed to the center of said arc-shaped pit by high frequency wave; said LED die is covered with a phosphor molding compound made by mixing phosphor and silica gel; and each one of said plurality of arc-shaped pits and its neighboring portion of PCB is covered by a window layer formed by transparent silica gel.