Abstract: The invention provides a holder frame, optical device and projector which can prevent the substrate from deviating in position, the substrate from being compressed at the outer periphery and color unevenness from occurring. More particularly, in the four sides of a luminous-flux incident surface of a holder frame, there can be formed a plurality of cutouts extending from a vicinity of an opening to an outer edge of the luminous-flux incident surface and nearly orthogonal to a lengthwise of each side. Also, in the four sides of an accommodating surface of the holder frame, there are formed a plurality of cutouts extending from a vicinity of an opening to an outer edge of the accommodating surface and nearly orthogonal to a lengthwise of each side. The cutouts in each side of the accommodating surface of the holder frame are formed in positions between the cutouts formed in each side of the luminous-flux incident surface of the holder frame as viewed from a side of luminance-flux incidence.

Abstract: The invention provides a fixing plate, optical device and projector capable of preventing against color unevenness occurrence and pixel deviation. Specifically, in each of the four sides of a luminous-flux exit surface of a plate part of a fixing plate, there can alternately be formed a first cutout in a groove form extending from an opening toward an outer edge of the plate part and nearly orthogonal to a lengthwise of each side, and a second cutout in a groove form extending from the outer edge toward the opening and nearly orthogonal to the lengthwise of each side.

Abstract: A method and apparatus is described to beam split or combine light for multiple fiber optic channels in a single device. Multiple light beams may enter the device through an array of fiber ports with each port having a collimating lens. The device includes a beamsplitter/combiner having a common optical aperture to simultaneously receive the light beams. The device may be used in laser amplification systems to combine lower power pump light beams into a single, higher power pump light beam.

Abstract: An optical combining device for combining the paths of two light beams having different polarizations is provided. The device includes a scroll direction change prism and a polarized beam splitter. The scroll direction change prism is disposed in the path of a first light beam and changes a scroll direction of the first light beam to as to be the same as that of a second light beam. The polarized beam splitter is disposed in the path of both the first light beam, reflected from the scroll direction change prism, and the second light beam and combines the first and second beams by selectively transmitting or reflecting them according to the polarization direction thereof.

Abstract: Multidirectional retroreflectors and methods of reflecting light beams from multiple directions are provided. The multidirectional retroreflectors utilize a four-mirror retroreflector with a common virtual reflection point.

Abstract: The invention relates to a device including a color separation prism, comprising at least two image sensors whose sensor surfaces are substantially of the shape of a rectangular parallelogram, and a color separation prism whose front surface of a functional part is planar and substantially of the shape of a rectangular parallelogram, whereby the front surface of the functional part of the color separation prism has a first side length and a second side length perpendicular thereto. In the device of the invention, the first side length of the front surface of the functional part of the color separation prism is substantially shorter than the second side length.

Abstract: The invention relates to a device for holding a beam splitter element having an optically active beam splitter layer in an optical imaging device, the beam splitter element being connected to at least one support element that is fastened in the housing of the imaging device. The connection between the beam splitter element and said at least one support element is designed in such a way that the position of the beam splitter layer of the beam splitter element remains nearly constant relative to the housing independently of temperatures and of thermal stresses acting upon the beam splitter element.

Abstract: An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an f/# less than or equal to 2.5. The Cartesian polarizing beam-splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam-splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces.

Abstract: The present invention provides beam array controllers for changing the spatial and optical characteristics of a beam array. Beam array pitch controllers are provided which are capable of selectively adjusting the spacing between adjacent beams in a beam array. Beam array pitch controllers are provided which are capable of selectively adjusting the brightness and brightness spatial distribution of a beam array. The present invention also provides optical sources for generating a beam array having a selectively adjustable pitch, brightness and brightness spatial distribution.

Abstract: A color combining optical system which can suppress occurrence of a thermal problem and increase in size is disclosed. The color combining optical system comprises a first optical element which has a first optical film reflecting light having a first polarizing direction and transmitting light in a second polarizing direction and combines the first and second color lights by the first optical film. In addition, the optical system comprises a polarizing plate which analyzes a third color light. Furthermore, the optical system comprises a second optical element which combines, by a second optical film, the third color light transmitted through the polarizing plate with the first and second color lights combined by the first optical element.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. The image of this display screen is focused in order to reduce the splitting volume and then split by a plurality of reflective surfaces located near the focal point of the image.

Abstract: A color-separating and -recombining optical system provided between a light source and a projection lens in a projection display, has at least one prism assembly made up of at least two prisms bonded to each other with a bonding layer formed between the prisms. A white light emitted from the light source is divided into red-, green-, and blue-color light components related to primary colors. The light components are modulated by spatial light modulators in accordance with a video signal. The modulated light components are combined and projected onto a screen via the projection lens. The thickness of the bonding layer is varied as thin and thick for optical paths long and short, respectively, from the spatial light modulators to the bonding layer which each modulated light component emitted from the corresponding spatial light modulator reaches.

Abstract: Laser beams emitted by a plurality of laser sources are divided into a plurality of sub-beams, which are irradiated onto selected portions of an amorphous semiconductor on a substrate to crystallize the amorphous semiconductor. A difference in diverging angles between the laser beams is corrected by a beam expander. The apparatus includes a sub-beam selective irradiating system including a sub-beam dividing assembly and a sub-beam focussing assembly. Also, the apparatus includes laser sources, a focussing optical system, and a combining optical system. A stage for supporting a substrate includes a plurality of first stage members, a second stage member disposed above the first stage members, and a third stage member 38C, rotatably disposed above the second stage to support an amorphous semiconductor.

Abstract: The subject invention relates to beam control prisms and the use of a beam control prism to modify the beam properties of light emitted from an edge emitting diode laser. The subject invention can utilize a beam control prism placed next to a diode laser bar. The subject beam control prism can have, for example, a curved surface and/or a high reflective coated surface for a diode laser wavelength. The curved surface can collimate the fast axis divergence and the mirror surface can change the beam direction. The subject curved surface beam control prisms can incorporate one or more features, such as parabolic reflecting surface, elliptical exit surface with flat reflecting surface, and a hyperbolic entrance surface with flat reflecting surface.

Abstract: An optical scanning apparatus includes a first optical member for receiving a plurality of light beams with an interval and for causing a first group of beams to emerge with a narrower interval, the first optical member being rotatable to adjust the interval of the beams emergent therefrom; a second optical member for receiving a second light beam and the first group of beams emergent from the first optical member with an interval and for causing a third group of beams to emerge with a narrower interval, the second optical member being rotatable to change the interval between the first group of beams and the second beam; and deflecting means for scanningly deflecting a third group of beams emergent from the second optical member.

Abstract: A color image projecting device includes an illuminating optical system and a projection optical system. The illuminating optical system includes a light source emitting white light including red, green, and blue colors, a dividing-spectra block having reflecting surfaces reflecting the red and blue colors of the light received from the light source toward left and right while transmitting the green color, a red block having a dichroic mirror provided in contact with the dividing-spectra block and reflecting the red color, reflected off the reflecting surface of the dividing spectra block, toward the projection optical system, a blue color block having a dichroic mirror like that of the red block, and a green block having a dichroic mirror reflecting the transmitted green color of light toward the projection optical system.

Abstract: Refracting optical system 1 and 2 relatively shift the second laser beam groups together with respect to the first laser beam groups along the layering direction. The transmission/reflecting optical system for alignment 1R, 2R, 1S and 2S are used, so that the laser beam patterns comprised of the first and second laser beam groups which are emitted from the transmission/reflecting optical systems 1R, 2R, 1S and 2S are shaped to be long in the layering direction of the laser bar, and since separate optical systems are used for shift and alignment, respectively, an individual optical system has a simple configuration.

Abstract: A viewing optical system of an optical apparatus has an objective system for forming an image of an object and an eyepiece system for enlarging and directing the image to the pupil. The viewing optical system also has a hologram combiner comprising holograms of the volume type, phase type, and reflective type and having optical power for constructing a surface which is optically equivalent to the image surface at a different position than the image when viewed from the pupil. The system also includes an information display means for displaying information at the position of the equivalent surface, wherein the hologram combiner transmits light from the image and reflects light from the information display means so as to allow viewing of an image together with the information display overlaid onto the image.

Abstract: An optical device for processing radiation that includes a beam splitter and a plurality of radiation processing parts arranged to process the characteristics of different radiation components separately, The polarizing beam splitter includes a wire grid polarizer, a first transparent plate arranged adjacent one side of the polarizer and a second transparent plate arranged adjacent the other side. Each of the first and second plates have substantially equal optical thickness profile.

Abstract: A three element prism system and method for splitting/combining three different colors of light arranged such that the size of a selected one of the color prism, such as for example, the red prism and, consequently the clear aperture, are increased without a corresponding increase in the size of the other prisms (e.g., the blue and green prisms). This is accomplished by adjusting the air gap A2 of the selected light path (e.g., red) so that the effective total selected light path T, which includes the selected light air gap A2 and the selected light glass path G2 is the same as the total path length T of both the other light paths (e.g., green and blue) comprised of air gap A1 plus glass path G1.

Abstract: A catadioptric objective is provided with a beam splitter surrounded at least partially by a mount, with a mirror, with a plurality of lenses and with a &lgr;/4 plate arranged between the mirror and the beam splitter.

Abstract: A bi-directional wavelength division multiplexing/demultiplexing device is disclosed. In an exemplary embodiment, the bi-directional wavelength division multiplexing/demultiplexing device comprises a diffraction grating for combining a plurality of monochromatic optical input beams into a multiplexed, polychromatic optical output beam, and for separating a multiplexed, polychromatic optical input beam into a plurality of monochromatic optical output beams; and a transmissive/reflective optical element for transmitting the plurality of monochromatic optical input beams on an optical path toward the diffraction grating, and for reflecting the plurality of monochromatic optical output beams received on an optical path from the diffraction grating.

Abstract: Pathlength matched optical devices (such as beam splitters) are produced by viewing optical paths through the optical devices and adjusting relative positions of optical components of the optical devices until the viewed optical paths are equivalent. The optical paths begin at markings at different locations on the optical device. The optical pathlengths are equivalent when both markings are in focus in a limited field of view camera or lens. In a beam splitting cube constructed of two prisms, markings located at precisely similar locations on different prisms are pathlength matched when coincident as viewed at a reference face of the cube. The prisms are abutted at their diagonals and are adjusted by sliding the prisms along the diagonals to the pathlength matched position. Optical adhesive between the prisms is cured after fixing the prisms at the pathlength matched position.

Abstract: The invention relates generally to optical interference filters and interferometers. Methods, devices and device components are presented for separating closely spaced optical channels with minimized cross talk. The invention provides optical interference filters having parallel phase control elements which efficiently transmit light of a selected optical channel or a plurality of selected channels with decreased light loss, particularly decreased insertion loss. An exemplary interference filter of the present invention provides minimized vertical and horizontal recombination error and improved optical path length matching. The invention further provides methods of fabricating optical interference filters with improved piece-to-piece reproducibility.

Abstract: The present invention relates to an image display apparatus, e.g. a head-mounted image display apparatus, in which an image from a single image display device is led to two eyes without using a half-mirror, thereby allowing observation of a bright image. The image display apparatus has an optical path distributing mirror 1 for distributing the image of a single display device 10 to an optical path for a right eye and an optical path for a left eye, and an ocular prism 2R for the right eye and an ocular prism 2L for the left eye, which are placed on the right- and left-hand sides, respectively, of the optical path distributing mirror 1.

Abstract: Methods for measuring and automatically controlling the light distribution and overall brightness in electronic-based spatial light modulator projection display systems. One method takes a small fraction of the projected light from a partial turning mirror 407 in the projector's optics path and focuses this light on to a detector 420 for use in controlling the light distribution and brightness of the system. Another method uses an array of embedded light sensors 518-522 at chosen locations on the surface of a display screen 517 to control the light distribution and brightness parameters of the projection system. Both methods use a micro-controller, servomotors, and an adjustable power supply, controlled by the detector/sensor outputs, to maintain the desired light distribution and brightness in the projected image.

Abstract: An image-exposing apparatus includes an optical device which mixes lights coming from different directions and emits a mixed light in a unilateral direction. The optical device includes first, second and third transparent members receiving first, second and third lights from first, second and third light-emitting element rows, respectively, a first composition plane, at which the first and second transparent members are joined and form a first light selective film, a second composition plane, at which the first and third transparent members are joined and form a second light selective film, and a wavelength controlling element which excludes a wavelength region of the first light from a region between a wavelength at which P-polarization changes from transmission to reflection in the first composition plane and another wavelength at which S-polarization changes from transmission to reflection in the first composition plane.

Abstract: An image display element 1 and an observation optical system 2 which forms an exit pupil 4 for observation of an image displayed on the image display element are included, wherein the observation optical system 2 has at least one surface 21 that has a lens function, and the following condition (1) is satisfied: 0.1<P·PD·ZD<5  (1) where P is a pixel pitch (in &mgr;m) of the image display element, PD is a diameter (in mm) of the exit pupil, and ZD is a distance (in mm) from the display surface of the image display element to the first surface having a lens function. Whereby, weight reduction is achieved while good image quality is maintained regarding an image display apparatus that is used for magnifying observation of an image on a display element.

Abstract: The multi-beam scanning device includes first and second light emitting elements that emit first and second light beams, respectively, a polygon mirror that deflects the first and second light beams to simultaneously scan the first and second light beams across an object. A prism having a light entrance portion and a light exit portion is located between the light emitting elements and the polygon mirror such that the first light beam enters the first prism through the light entrance portion and exits from the first prism through the light exit portion toward the polygon mirror. The light exit portion is inserted into the optical path of the second light beam to prevent a part of the second light beam from proceeding toward the polygon mirror.

Abstract: In a color separating optical system, a first filter adapted to eliminate from light emitted from a red light exit face a light component in a wavelength range longer than a longer-wavelength-side boundary wavelength of a red visible light wavelength region is disposed at a prism surface in an optical path for guiding red region light, whereas a second filter adapted to reflect a light component in a wavelength range longer than a reference wavelength which is longer than the longer-wavelength-side boundary wavelength by a predetermined wavelength but transmit therethrough a light component in a wavelength region shorter than the reference wavelength is placed at the red light exit face.

Abstract: Red, green and glue light beams from light source portions (301, 302, 303) are modulated respectively by light valve units (317, 319, 321) of a light valve portion (304) and enter a color combination optical system (305). The color combination optical system (305) includes three triangular prisms (325, 326, 327), each having a vertex angle of about 30 degrees, and is formed by joining the prisms together with dichroic mirror surfaces (328, 329) interposed therebetween. The respective light beams entering the planes of the prisms opposite to their vertex angles are combined in the color combination optical system (305) and emitted from an exit plane of the prism (327). The optical path lengths of the respective light beams between the incidence planes and the exit plane (332) are substantially equal to one another. Then, a projection lens (306) magnifies and projects the combined light beam onto a screen.

Abstract: A beam splitter for a digital camera splits light passed through a photographing lens into beams directed to a CCD and a finder optical system. The beam splitter includes at least one optical element provided with a beam splitting surface that is inclined with respect to an optical axis of the photographing lens, and a multi-layer film including a plurality of layers of dielectric materials is formed on the beam splitting surface. The multi-layer film is configured such that the beam splitting surface exhibits a substantially constant reflectivity at least for visible light that is incident on the beam splitting surface at any incident angle within a predetermined range.

Abstract: A de-centered optical system includes a first optical element having at least three surfaces surrounding a portion having a refractive index of more than 1, and a second optical element whose surface further from the first optical element is a convex surface and has a positive power and produces chromatic aberration of magnification. When the de-centered optical system is used as an ocular optical system of an image observation apparatus, the image size observed through the de-centered optical system in the blue wavelength is larger than that formed in the green wavelength, and that formed in the green wavelength is larger than that formed in the red wavelength. The difference can be compensated by an electronic compensation means. This optical system can be used as an image taking optical system by setting the light traveling direction inversely to that in case when it is used as an ocular optical system.

Abstract: An optical path switch and a method of using thereof, for creating two optical pathways for input light. The switch is composed of two polarizers that polarize the input light and two polarization rotators each having two positions. The polarization rotators position translates to one of two the optical pathways. Additionally, the optical path switch has an image enhancement device for producing an enhanced image of the light, and a beam splitter that directs the light to two channels. The optical path switch works by polarizing the light by one of the two polarizers producing an output, following, the output is then directed through the beam splitter where the output is directed towards the two channels. Next, the output is then filtered through the two polarization rotators and to the other of the two channels where the positions of the two polarization rotators switch the optical pathways.

Abstract: A display having a two-stage optical process is disclosed. This two-stage system enables a relatively compact and inexpensive display. A display screen projects an image that passes through a first lens or lens system. The collimated light is then diffused by one of several methods so as to increase the ultimate viewer's eyebox. The diffused image then undergoes a magnification process involving total internal reflection within a second lens. The light exiting the second lens is magnified to the level desired at a low cost and a small size.

Abstract: A light modulator is comprised of two unit devices each using surface plasmon generated at the interface between thin metal films respectively formed on prisms and an electro-optical material, and a mirror. Both of the transmitted light due to absorption and re-radiation, and the reflected light arising from the unit devices are made into the outgoing light, the incident light on the next unit device, or the incident light on the mirror. Consequently, all light beams can be utilized as the final outgoing light beams with no loss of light. Further, the color of light can be spatially divided, and still further, it can also be temporally divided by changing the wavelength due to a voltage. As a result, the original light can be divided both temporally and spatially with almost no loss by combining two unit devices so configured as to re-radiate the absorbed light by surface plasmon using surface plasmon and a mirror, and thus utilizing both of the reflected light and the transmitted light.

Abstract: In an image observation apparatus, image light is guided to an observer's eye by using a first refractive surface on which the image light from an image display device is made incident, a reflective surface for reflecting the image light made incident from the first refractive surface, and an optical element having a second refractive surface for emitting the image light reflected from the reflective surface. A diffraction optical part is provided in front of the reflective surface of the optical element.

Abstract: A imaging tool for use with a mask with features oriented along at least an x-axis or a y-axis where the x-axis extends in directions substantially perpendicular to the directions of the y-axis. The tool has a condenser lens with a condenser plate which is located in a condenser lens pupil plane and which has a condenser aperture with four-sides. The sides of the condenser aperture are oriented in substantially the same direction as either the x-axis or the y-axis. The condenser lens is positioned to place at least a portion of any illumination on at least a portion of the mask.

Abstract: An enhanced illumination system for a micro-display comprises an illuminator for a reflective display panel having a light source and a prism. The prism has a first substantially planar face proximate to the light source and to the display panel, so that light propagates from the light source into the prism through the first face and is redirected to the display panel through the first face. A second face of the prism is positioned opposite the light source so that light reflected from the display panel impinges on the second face and propagates to imaging optics. The illuminator may also include an auxiliary prism optically coupled to the second face of the first prism to correct for astigmatism of the reflected light from the display panel and a beam splitter between the first prism and the auxiliary prism.

Abstract: A partially reflecting optical component (11) generating, from an incident beam (12), two secondary beams, one of them being reflected (13), the other one being transmitted (14). According to the invention, it comprises a first wholly reflecting planar face (15) and a second partially reflecting planar face (16), the second face being perpendicular to the first one, a third wholly reflecting planar face (17), the first and third faces being in the same plane, this component providing the unidimensional auto-alignment of the reflected beam (13) with the incident beam (12), the respectively transmitted and reflected beams being each formed with two half-beams having matching wave fronts. The invention also relates to an external cavity laser source comprising such a component as a unidimensional auto-aligned reflector.

Abstract: A beam splitter has a support frame made of silicon that has a membrane inside made of silicon. The membrane has in particular openings with bridges formed between them. On the side of membrane facing the incident beam is an aluminum coating to increase the reflectability or degree of reflection of the membrane. An incident beam bundle contacts the beam splitter at angle of incidence &phgr;. A portion of the incident beam is reflected off the bridges, and the remaining portion of the beam freely passes through the openings. The beam is correspondingly divided into a reflective portion and transmitted portion.

Abstract: The present invention provides an enhanced viewing eyepiece for a micro-display. In one embodiment, the invention is an optical imaging system that includes a prism having a first face directed toward a display to receive light from the display and direct it through a second face, a converging optical element between the second face of the prism and the display, and a reflective converging optical element adjacent the second face of the prism to receive the display light through the second face of the prism and reflect it back into the second face of the prism, the invention further includes a diverging optical element aligned with the reflective converging optical element to receive the display light reflected back into the first prism and direct it to an exit pupil.

Abstract: An observation optical system or a photographing optical system comprises, between a pupil surface and an image surface, a first prism 3 and a second prism. The first prism 3 includes a 1st-1st surface 31 which has both of actions of transmitting and reflecting light in the path, a 1st-2nd surface 32 which has both of actions of reflecting and transmitting the light in the path, and a 1st-3rd surface 33 which transmits the light in the path. The second prism 4 includes a 2nd-1st surface 41 which is disposed adjacent to the 1st-2nd surface 32 at an air space away and which transmits the light in the path at least twice and a 2nd-2nd surface 42 which reflects the light in the path. The 1st-1st surface 31 is constructed of a prism face to which a volume hologram 6 is applied.

Abstract: In a color separating optical system, a first filter adapted to eliminate from light emitted from a red light exit face a light component in a wavelength range longer than a longer-wavelength-side boundary wavelength of a red visible light wavelength region is disposed at a prism surface in an optical path for guiding red region light, whereas a second filter adapted to reflect a light component in a wavelength range longer than a reference wavelength which is longer than the longer-wavelength-side boundary wavelength by a predetermined wavelength but transmit therethrough a light component in a wavelength region shorter than the reference wavelength is placed at the red light exit face.

Abstract: A light modulator is comprised of two unit devices each using surface plasmon generated at the interface between thin metal films respectively formed on prisms and an electro-optical material, and a mirror. Both of the transmitted light due to absorption and re-radiation, and the reflected light arising from the unit devices are made into the outgoing light, the incident light on the next unit device, or the incident light on the mirror. Consequently, all light beams can be utilized as the final outgoing light beams with no loss of light. Further, the color of light can be spatially divided, and still further, it can also be temporally divided by changing the wavelength due to a voltage. As a result, the original light can be divided both temporally and spatially with almost no loss by combining two unit devices so configured as to re-radiate the absorbed light by surface plasmon using surface plasmon and a mirror, and thus utilizing both of the reflected light and the transmitted light.

Abstract: A laser beam attenuator and a method of attenuating a laser beam are disclosed. The laser beam attenuator includes first and second prisms, a beam dump, and a light absorbing body. An input laser beam partially refracts and partially reflects at a first surface of the first prism to form first refracted and reflected laser beams. The first reflected laser beam partially refracts and partially reflects at a second surface of the second prism to form second refracted and reflected laser beams. The beam dump and the light absorbing body absorb the first and second refracted laser beams. Thus, the second reflected laser beam forms an attenuated laser beam.

Abstract: The present invention improves the precision of color synthesis and suppresses the generation of vertical stripes in the projected image, and includes at least the following three aspects.

Abstract: The present invention is an apparatus for monocular head displays, which enables a compact, light in weight, sturdy apparatus that has a wide angle of viewing, a bright and sharp image display that operates on low voltage in a wide range of temperatures. The image is bright and high in contrast. Due to the compactiveness and wide viewing angle, it is readily useable inside helmets and goggles and visors. The signals that can be used include data, maps, graphics or video images including infrared or other images. Because of the wide viewing angle, the module may be placed and adjusted for multiple users and field installation.

Abstract: There is provided a catadioptric projection objective that includes (a) an object plane having a rectangular object field, and (b) a beam splitter situated in a light path after the object plane, having a rectangular surface adapted to the object field and having an aspect ratio not equal to 1.

Abstract: The present invention provides an ultraviolet (UV) polarizing beam splitter cube. The UV polarizing beam splitter cube is transmissive to light at wavelengths equal to or less than 170 nm and can image, at high quality, light incident over a wide range of angles and including a numeric aperture greater than 0.6. The UV polarizing beam splitter cube comprises a pair of prisms that are made of at least a fluoride material, and a coating interface having at least one layer of a thin film fluoride material. Alternating layers of thin film fluoride materials can comprise a first fluoride material having a first refractive index and a second fluoride material having a second refractive index. The first and second fluoride materials form a stack of fluoride materials having relatively high and low refractive indices such that the coating interface separates UV light into two polarized states.