Abstract: A brightness enhancement film including a monolithic layer and a microstructured layer adjacent the monolithic layer. The microstructured layer has a first major surface and an opposing second major surface. The first major surface includes a first plurality of microstructures and the second major surface faces the first monolithic layer. The monolithic layer includes a polyester that includes at least about 70 mole percent naphthalenedicarboxylate groups based on total carboxylate groups. The polyester may include one or more catalysts having a total concentration by weight in a range of 10 to 1000 ppm. The first monolithic layer has a thickness in the range of about 5 ?m to about 300 ?m. The first monolithic layer may be substantially free of non-catalyst particulate matter and may have a haze of less than 1 percent.

Abstract: Light deflector includes: polygon mirror made of plastic and having reflecting surfaces; motor rotatable on a rotation axis; and rotor rotatable by the motor, and including base portion intersecting the axis of rotation, and first protruding portion having circular cylindrical shape and protruding from the base portion in a rotation-axis direction. The polygon mirror has inner surface contacting outer peripheral surface of the first protruding portion, and bottom surface facing to the rotor in the rotation-axis direction. The bottom surface has contacting portion contacting the base portion, and the contacting portion overlaps a line segment connecting the rotation axis and any of vertexes of the polygon mirror viewed from the rotation-axis direction. The bottom surface has non-contacting portion spaced apart from the base portion, and the non-contacting portion overlaps a perpendicular dropped from the rotation axis to any of the reflecting surfaces viewed from the rotation-axis direction.

Abstract: A spherically mounted retroreflector (SMR) includes a replicated optic, a substrate, and an adhesive. The replicated optic, which includes a cube-corner retroreflector, has a base area smaller than the retroreflector area. The substrate has a partially spherical outer surface and a cavity sized to accept the replicated optic. An adhesive attaches the optic to the substrate.

Abstract: A technique is provided which enables preparation of a curved grating having a desired curvature, by plastically deforming, along a curved substrate, a flat grating prepared by a semiconductor process on a silicon substrate, and which thus prepares a diffraction grating with high accuracy. A silicon flat grating prepared by a semiconductor process is transferred to an amorphous material, and the amorphous material substrate is curved and mounted on a curved fixed substrate, thus providing a curved grating having a crystalline material in which the generation of a dislocation line is restrained.

Abstract: A glass plate has, at least at a part of an outer edge, an adjacent surface that intersects a principal plane at an obtuse angle, wherein the adjacent surface is a cutting plane formed by an extension of a crack, and the adjacent surface forms a diffraction grating including at least one of a Wallner line and an Arrest line.

Abstract: A photosensitive resin composition includes (A) a black colorant having a maximum transmittance in an ultraviolet (UV) wavelength range/minimum transmittance in a visible ray wavelength range of about 30 or greater, (B) a binder resin; (C) a photopolymerization initiator; (D) a photopolymerizable monomer; and (E) a solvent. A black column spacer using the photosensitive resin composition, and a color filter including the black column spacer are provided.

Abstract: A transparent heat-shielding member according to the present invention includes a transparent base substrate, an infrared reflective layer and a transparent screen function layer. The infrared reflective layer includes at least one selected from a metal oxide layer and a metal nitride layer, and a metal layer. The transparent screen function layer is formed of a light diffusing layer. The light diffusing layer contains light diffusing particles and a transparent resin. The light diffusing particles are dispersed in the transparent resin. The transparent heat-shielding member has a visible light reflectance measured in accordance with JIS R3106-1998 of 12% or more and 30% or less, a haze value measured in accordance with JIS K7136-2000 of 5% or more and 35% or less, and a shading coefficient measured in accordance with JIS A5759-2008 of 0.69 or less.

Abstract: Disclosed is a color material dispersion liquid for color filter, which has excellent heat resistance and is able to form a high-luminance coating film. The color material dispersion liquid for color filters includes (A) a color material, (B) a dispersant and (C) a solvent.

Abstract: The present invention provides a red coloring composition for use in a color filter, which can form a red colored film having low incident-angle dependence and improves the color-separation properties of a solid-state imaging device including the colored film; and a colored film, a color filter, and a solid-state imaging device. The red coloring composition for use in a color filter of the present invention is a red coloring composition for use in a color filter, containing a red colorant, a near-infrared absorbent, and a polymerizable compound, in which when the coloring composition is used to form a colored film having a film thickness of 0.8 ?m, the maximum value of the transmittance at a wavelength from 400 nm to 550 nm of the colored film is 7% or less, the minimum value of the transmittance at a wavelength from 600 nm to less than 700 nm of the colored film is 80% or more, and the minimum value of the transmittance at a wavelength from 700 nm to 900 nm of the colored film is 30% or less.

Abstract: A high energy, low temperature cold plasma thin film deposition process, apparatus and products are disclosed. Multi-layer thin film coatings are deposited onto polymeric substrates for ophthalmic and therapeutic applications.

Abstract: Provided is an optical laminate including a resin layer and an adhesive layer, and being excellent in adhesiveness between these layers. The optical laminate includes: a resin layer; an adhesive layer arranged on at least one side of the resin layer; and an intermediate layer formed between the resin layer and the adhesive layer, the intermediate layer containing at least part of a material constituting the resin layer and at least part of a material constituting the adhesive layer, in which the intermediate layer has a thickness of from 20 nm to 200 nm. In one embodiment, the resin layer includes a resin film having optical anisotropy.

Abstract: A light device using a light cylinder is disclosed. The light device includes a cover, a light source section combined with one or more sides of inside sides of the cover and configured to output a light, and a light cylinder configured to include one entrance part and plural output parts. Here, the entrance part is combined with the light source section, and the light incident through the entrance part is outputted through the output parts.

Abstract: The present disclosure provides a backlight source, including: a light-guide plate, a diffuser arranged at a light-exiting side of the light-guide plate, and a light bar arranged at a light-entering side of the light-guide plate and including a light-emitting diode (LED) lamp and a flexible circuit board connected to the LED lamp. The flexible circuit board includes a base material, and a first solder mask and a second solder mask arranged at two surfaces of the base material opposite to each other. The base material includes a first region where the second solder mask is arranged and a second region where the second solder mask is not arranged. The second region is located at a side of the base material adjacent to the light-guide plate. The diffuser includes, at an end adjacent to the light bar, a connection member partially or completely covering the second region.

Abstract: A light guide plate, a backlight module and a display device employing the same. The light guide plate is configured to guide light emitted from an LED lamp on an LED lamp strip, and a light incident surface of a side portion of the light guide plate is provided with an indentation; when the LED lamp is locked in the indentation, a light emitting center line of the LED lamp coincides a light incident center line of the light guide plate. The backlight module includes a light guide plate, and the display device includes the above backlight module.

Abstract: An apparatus comprising a light source (110), one or more light guides (104), and a light diffuser (102) having an integration chamber (114) surrounded by one or more light diffusive areas (108). The one or more light diffusive areas are configured with one or more first openings as one or more ingress areas (112) to receive light from the light source and one or more second openings as one or more egress areas (106) to provide light to the one or more light guides. For illuminating visual indicators with uniform light.

Abstract: A lighting assembly comprises a light source and a light guide having a light input edge and a light output surface. Light from the light source enters the light input edge and is propagated within the light guide by total internal reflection. A light adjustment element is adjustable or selected to achieve a desired property of the light within the light guide.

Abstract: A cabinet lamp is provided, including a connection substrate, a light guide plate and a top cover. There is a light emitting area on the connection substrate. On the top cover, there is a light emitting window corresponding to the light emitting area. The top cover presses the light guide plate onto the light emitting area. Light sources are disposed on the light emitting area and along the circumferential direction of the light guide plate. On the inner surface of the top cover, there is a protruded border along the circumferential direction of the light emitting window. A reflective surface is formed between the protruded border and the light emitting window. The reflective surface can reflect the light emitted from the light sources to the side face of the light guide plate. The side face of the light guide plate toward the light emitting area has a recessed structure.

Abstract: The present disclosure provides a backlight module, a display module and a display device. The backlight module includes a plurality of backlight components in connection. Each backlight component includes: a light guide plate; a plurality of light emitting diodes (LEDs) provided on a light entering side of the light guide plate; a deformable layer provided on a light exiting side of the light guide plate. A thickness of the deformable layer is changeable under a pressure so as to deflect original light rays from at least a portion of LEDs of the plurality of LEDs.

Abstract: This disclosure provides systems, methods and apparatus for providing stacks of optical films that may be used to provide increased on-axis display brightness. In one aspect, an apparatus or system may be provided that includes a light source, a first optical film having triangular cross-section, prismatic light-turning structures, and a second optical film having trapezoidal cross-section, prismatic light-turning structures. The first optical film may be interposed between the light source and the second optical film. In further aspects, a third optical film, similar to the first optical film, may be interposed between the light source and the first optical film. In yet further aspects, one or more additional optical films, similar to the second optical film, may be positioned in the stack such that the second optical film is between the first optical film and the additional optical film(s).

Abstract: Disclosed are a dual viewing film and a dual view display apparatus using the same, and the dual view display apparatus includes left and right edge emitting light sources (for example, LED light sources), a dual viewing film having a prism pattern and a lens shape at a lower surface of a substrate; a structured light guide plate, and a display panel (for example, an LCD panel) having a high refresh rate, thereby displaying different images, of which resolution is not reduced, to viewers in left and right directions.

Abstract: The present technology relates to luminaires including a housing and a luminaire module disposed within the housing, where the housing has apertures through which light that is output by the luminaire module exits the luminaire towards one or more target areas.

Abstract: The present invention relates to a light guide plate (LGP) capable of bidirectional focusing via a bidirectional micro-transmissive layer, a fabrication method of the LGP, an extrusion equipment, a backlight module and a display device. The LGP comprises a LGP substrate, the LGP substrate comprises at least one incident surface for receiving a light beam and one outgoing surface connected to the incident surface, a bidirectional micro-transmissive layer is provided in the LGP substrate, the bidirectional micro-transmissive layer comprises a plurality of micro-transmissive points having biconvex surfaces.

Abstract: A method of manufacturing a light guide plate includes steps of cutting a light guide plate base material with a frame-shaped die into a die-cut plate 50 including side surfaces each having a rectangular shape and performing thermal-imprinting process. In thermal-imprinting process, a processing surface 60a of a plate surface of a heated processing board 60 is pressed against one of the side surfaces 52 of the die-cut plate 50 to thermally imprint a pattern of the processing surface 60a of the processing board 60 on the one of the side surfaces 52 of the die-cut plate 50. The processing surface 60a having a shape that is recessed more at a portion thereof opposite a middle of a long dimension of the one of the side surfaces 52 than a portion thereof opposite ends of the long dimension of the one of the side surfaces 52 is pressed against the side surface 52.

Abstract: Provided are a light guide member, a lighting apparatus including the light guide member, and a method of fabricating the light guide member. The light guide member comprises: a body, which is formed as a transparent plate, including a first surface and a second surface facing the first surface; and a plurality of dimple type optical controllers formed beneath at least one of the first surface and the second surface and having reflective surfaces that reflect light proceeding between the first and second surfaces of the body toward at least one of the first and second surfaces.

Abstract: The present invention discloses a radiator, where the radiator includes a mounting portion used for mounting a heat source, a radiating portion connected with the mounting portion and used for absorbing heat transferred by the mounting portion, the radiating portion is internally provided with multiple radiating pipelines, the radiating pipelines are internally injected with liquid, and the liquid in the radiating pipelines is gasified after absorbing heat on one end where the radiating portion is close to the mounting portion, and in the radiating pipelines, moves from one end where the radiating portion is close to the mounting portion towards one end where the radiating portion is away from the mounting portion. The present invention further discloses a backlight module, and the present invention further discloses a display module. The present invention effectively improves the heat transfer effect, and effectively enhances the radiating effect.

Abstract: The present invention discloses a light guide plate fixed to a back plate. The back plate has a plurality of fixing portions. The light guide plate includes a light incident surface, a reflective surface connected with the light incident surface, and a light output surface opposite to the reflective surface and connected with the light incident surface. The light output surface includes a main body and a plurality of locating portions mounted on the main body. The locating portions correspond to the fixing portions. The locating portions mate with the corresponding fixing portions thereby fixing the light guide plate to the back plate. A blank area is formed on the main body at each location where each of the locating portions mating with the corresponding fixing portion. A plurality of microstructures are formed on the rest area excluding the blank areas in the main body.

Abstract: A liquid crystal display device (10) is provided with: an LED (24); a rectangular optical sheet (18) for imparting an optical action to light from the LED (24); a rectangular liquid crystal panel (11) disposed so as to be layered on the optical sheet (18); and a frame (15) constituting a frame shape, disposed so as to enclose the optical sheet (18), and sandwiching both edges on the long side of the optical sheet (18) between the liquid crystal panel (11) and itself while selectively pressing portions of the optical sheet (18) that are closer toward the center than the two end sides of the edges. Because the two edges on the long side of the optical sheet (18) are selectively sandwiched to hold the optical sheet (18) in place, displacement of the optical sheet (18) can be prevented or minimized. A deflection occurring in the optical sheet (18) can be relieved in a portion of the optical sheet (18) which is not sandwiched nor held in place, i.e., the portions on the two end sides of the edges.

Abstract: A display device includes a curved display panel and a backlight unit. The backlight unit includes a light guide film and a light source unit. The light guide film defines: a light emission part thereof facing the display panel, a folding part thereof extending from the light emission part to be folded in a folded state of the light guide film, and a light incident part thereof extending from the folding part to face the display panel with the light emission part therebetween, The light incident part is extended at a first end thereof from the folding part and defines a light incident surface of the light guide film at a second end of the light incident part opposite to the first end thereof. The light source unit is overlapped with the light emission part and face the light incident surface.

Abstract: A display device includes: a display panel which display an image using light; a light source which generates and provides the light to the display panel; a circuit board on which the light source is mounted; a fixation frame on which the light source and the circuit board are disposed; and a lower frame on which the display panel is disposed and in which the light source, the circuit board and the fixation frame are disposed. The lower frame defines: a bottom portion thereof overlapping the display panel, and an accommodation portion thereof extending from an end portion of the bottom portion and on which the light source, the circuit board and the fixation frame are disposed. The circuit board extends to cover the accommodation portion.

Abstract: The present disclosure provides a backlight source and a display apparatus. It relates to the field of display technology and solves the problem of poor display quality of the display apparatus. The backlight source comprises: a light guide plate; a light shielding tape arranged at a peripheral edge of a light emitting face of the light guide plate; a buffer layer arranged on the light shielding tape, wherein the buffer layer is provided with at least one lightening hole and/or at least one marking hole representing product information of the backlight source. The above backlight source may reduce the weight of the buffer layer by providing the lightening hole and/or marking hole on the buffer layer, so as to reduce the pressure of the buffer layer to the light shielding tape. In this way, the deformation in the light shielding tape 1 is reduced so as to improve display quality of the display apparatus.

Abstract: An optical fiber includes a monolithic elongated mosaic core having a longitudinal axis and configured with a silica-based medium with a uniform refractive index, and a plurality of coaxial elongated individual elements which do not waveguide light at a given wavelength and are received in the silica-glass medium. The refractive indices of the medium and individual anti- waveguiding elements together determine a cumulative effective refractive index of the mosaic core. The optical fiber further includes at least one cladding surrounding the mosaic core and provided with a cladding refractive index which is lower than the index of the mosaic core, so that the mosaic core waveguides the light at the given wavelength.

Abstract: A semiconductor substrate, an insulating layer made of silicon oxide formed on the semiconductor substrate and a semiconductor layer made of silicon formed on the insulating layer are provided, and the semiconductor layer constitutes an optical waveguide in an optical signal transmission line section and an optical modulator in an optical modulation section. Also, the insulating layer is removed except for a part thereof to have a hollow structure with a cavity, and both side surfaces and a lower surface of each of the semiconductor layers constituting the optical waveguide and the optical modulator are exposed and covered with air.

Abstract: An optical manipulator includes a first section for propagating an optical signal with multiple polarization modes including a transverse electric (TE) mode and a transverse magnetic (TM) mode and a second section for propagating separately the TE mode and the TM mode of the optical signal. The optical manipulator also includes a multi-mode interference (MMI) section having a groove with a first refractive index less than a second refractive index of the MMI section. The groove extends along an entire length of the MMI section to partition the MMI section into two connected channels including a first channel and a second channel. The first section is connected to the first channel and the second section is connected to both the first and the second channels.

Abstract: An arrayed waveguide grating device and a method for manufacturing the arrayed waveguide grating device. The arrayed waveguide grating device includes input channel waveguides formed on a substrate; output channel waveguides formed on the substrate that correspond to the input channel waveguides; and arrayed waveguides with different lengths interposed between the input channel waveguides and the output channel waveguides on the substrate while free propagation regions being formed at both ends of the arrayed waveguides, wherein the arrayed waveguides are designed so that a free spectral range (FSR) of a higher-order mode is twice or greater than a bandwidth of a region of interest (ROI).

Abstract: A method of forming an optical device includes using a photomask to form a first mask on a device precursor. The method also includes using the photomask to form a second mask on the device precursor. The second mask is formed after the first mask. In some instances, the optical device includes a waveguide positioned on a base. The waveguide is configured to guide a light signal through a ridge. A heater is positioned on the ridge such that the ridge is between the heater and the base.

Abstract: A slab of a rib waveguide includes geometric disruption features along a direction of propagation of the waveguide. The geometric disruption features scatter optical modes other than the fundamental mode in the slab without significantly impacting the fundamental optical mode that propagates primarily in the rib waveguide. The rib waveguide has a width to constrain the fundamental mode, and the fundamental mode primarily propagates through the rib waveguide, with some of the energy propagated via the slab. When the slab includes edges that are wider than the rib waveguide and smaller than the substrate on which the rib waveguide and slab are integrated, the slab can propagate optical modes other than the fundamental mode, such as higher-order modes. The geometric disruptions scatter the non-fundamental optical modes from the slab. The geometric disruptions can include serration features in one or both edges of the slab.

Abstract: An optical device includes a first fiber; a liquid crystal member configured to have liquid crystal pixels that reflect light output from the first fiber; a second fiber configured to have a core to which a first order light ray in the light reflected by the liquid crystal member is optically connected; a light receiving circuit configured to receive higher order light rays in the light reflected by the liquid crystal member; and a control circuit configured to control based on a light receiving result of the light receiving circuit, efficiency of optical connection of the first order light ray to the core of the second fiber, by varying an angle of the light reflected by the liquid crystal member.

Abstract: An optical demultiplexing apparatus and method for multi-carrier distribution are provided. The optical demultiplexing apparatus may include a demultiplexer and a carrier distributor. The optical demultiplexing apparatus and method allow efficient demultiplexing of a multi-carrier light source by using a single demultiplexer even when a carrier spacing of the light source varies.

Abstract: [Problem] A configuration is provided to suppress optical loss without providing a lens in the ferrule, and to make the filling operation of refractive index matching material easy with such a configuration. [Solving means] A ferrule with a fiber of this disclosure includes: a ferrule including a positioning hole, a plurality of fiber holes, and an endface perpendicular to an axial direction of the fiber holes; a lensed fiber with a GRIN lens that has been fusion spliced to a tip of an optical fiber; and a plate that can transmit light propagating through the optical fiber, the plate being attached to the endface of the ferrule, the plate being contacted against with an endface of the lensed fiber that has been inserted into each of the fiber holes, wherein the ferrule is formed with a recess that is depressed from the endface of the ferrule, a refractive index matching material is filled in a space surrounded with the plate and the recess.

Abstract: The number of wavelength selective switch (WSS) units in a WSS device can be doubled by using polarization properties of optical beams propagating through the WSS device. Beams from different WSS units are orthogonally polarized at the front end, propagated through collimator, wavelength dispersing element, and a focusing element, and impinge on a polarizing beamsplitter, which directs sub-beams at different polarizations to different directing elements of a director array. A polarization diversity configuration at the back end can be used to reduce polarization dependent loss.

Abstract: A hybrid plug connector including an insulative housing defining a cavity to receive an optical fiber assembly therein, and a plurality of passageways to receive a plurality of terminals therein. A printed circuit board is located behind the terminals and connected to the terminals. An electrical cable is mounted to a rear portion of the circuit board. The whole optical fiber assembly is received within the housing and is somewhat back and forth moveable along a front-to-back direction for buffering for compliantly coupling with another optical fiber assembly built within the complementary receptacle connector when the plug connector is inserted into the complementary receptacle connector. A lens module is formed on the optical fiber assembly for collimating the light beams from the optical fibers.

Abstract: A unitary multi-fiber ferrule has micro-holes for optical fibers, and a plurality of lenses disposed adjacent the front end, each of the plurality of lenses optically aligned with one of the micro-holes and exposed to air. Multiple rows of optical fibers and lenses may also be used in the unitary multi-fiber ferrule. The lenses have a divergence half angle of between about 2 and 20 degrees and may also have protrusions on them acting as an antireflective coating.

Abstract: A hybrid plug connector including an insulative housing defining a cavity to receive an optical fiber assembly therein, and a plurality of passageways to receive a plurality of terminals therein. A printed circuit board is located behind the terminals and connected to the terminals. An electrical cable is mounted to a rear portion of the circuit board. The whole optical fiber assembly is received within the housing and is somewhat back and forth moveable along a front-to-back direction for buffering for compliantly coupling with another optical fiber assembly built within the complementary receptacle connector when the plug connector is inserted into the complementary receptacle connector. An attachment shows the manufacturing process.

Abstract: The present disclosure relates to a fiber optic connector including a connector housing having a distal end and a proximal end. The distal end can form a plug portion adapted for insertion within a receptacle of a fiber optic adapter. A rear insert mounts within the proximal end of the connector housing. An axial insertion/retention interface can be defined between the connector housing and the rear insert. The axial insertion/retention interface can be configured to allow the rear insert to be inserted into and removed from the proximal end of the connector housing along an insertion axis when the rear insert is positioned in a first rotational position about the insertion axis relative to the connector housing. The axial insertion/retention interface can also be configured to prevent the rear insert from being withdrawn from the proximal end of the connector housing along the insertion axis.

Abstract: Disclosed is an optical connector ferrule including a main body portion having inside a plurality of optical paths that are parallel that are to each other; and a reinforcing member having a face parallel to an alignment direction of the plurality of the optical paths and having a linear expansion coefficient that is smaller than the linear expansion coefficient of the main body portion, wherein the reinforcing member has on a face of the optical path side thereof at least two limiting portions each having a face that limits an expansion and a contraction of the main body portion in the arrangement direction, the limiting portions being spaced apart in the arrangement direction.

Abstract: An apparatus for manufacturing an array of optical fiber using a handling tool, a clamp element, a cutter and an adhesive reservoir. The handling tool is capable of moving a portion of an optical fiber in a three-dimensional space and hold the portion of the optical fiber together with the clamp element to allow the cutter to produce a cleaved end in the optical fiber. The handling tool is further configured for immersing the cleaved end of the optical fiber in the adhesive reservoir and inserting the cleaved end of the optical fiber with adhesive adhered thereto inside a ferrule of an array of ferrules. A structure comprising the array of ferrules and a method of manufacturing an array of optical fibers are also disclosed.

Abstract: Disclosed is manufacturing method of an optical module including an optical/electrical converter, a receptacle, and a substrate, the method including: the receptacle that has a guide portion that aligns an optical connector ferrule that holds an end portion of an optical fiber and that has a device accommodating portion that matches with a profile of the optical/electrical converter; a process of accommodating the optical/electrical converter in the device accommodating portion; a process of securing the optical/electrical converter to the receptacle; and a process of electrically connecting to the substrate that electrically connects to the optical/electrical converter the optical/electrical converter secured to the receptacle.

Abstract: An optical module-member is provided, including: a layer-shaped optical waveguide; a light-emitting unit substrate including an insulating substrate, light-emitting element-mounting portions where light-emitting elements are configured to be mounted so as to be optically connected to the optical waveguide, and driving element-mounting portions which are electrically connected to the light-emitting element-mounting portions where driving elements for driving the light-emitting elements are configured to be mounted; and a light-receiving unit substrate which is separated from the light-emitting unit substrate, the light-receiving unit substrate including: an insulating substrate, light-receiving element-mounting portions where light-receiving elements are configured to be mounted so as to be optically connected to the optical waveguide, and signal amplification element-mounting portions which are electrically connected to the light-receiving element-mounting portions and where signal amplification elements for

Abstract: An optical block includes a first surface that receives light entering the optical block, a second surface through which the light exits the optical block, and a reflector that reflects light from the first surface towards the second surface. The reflector includes a textured surface that scatters or absorbs some of the light received from the first surface to attenuate the light exiting the optical block through the second surface.

Abstract: An optical device and an optic transceiver device are provided. The optical device includes a light splitting surface. The optical device further includes a first surface and a second surface disposed opposite to each other and parallel to each other. The light splitting surface separately intersects the first surface and the second surface. An angle between the light splitting surface and the first surface is not equal to 90 degrees. A medium between the light splitting surface and the first surface and a medium between the light splitting surface and the second surface are the same. The medium is formed by a light transmissive material.