Abstract: Disclosed is a waveguide having a light inlet surface and a viewing surface comprising stacked core layers separated by clad layers to form channels and bearing a smoothing layer on at least one of the light inlet surface or the viewing surface thereof.

Abstract: A capillary optic produced by impression has a mold with an external profile figured for radiation transmission along an axis used as a mandrel for impression. The mold often takes the form of a precisely etched wire. At least one soft plate is used for impressing the mold into the soft plate. The mold is removed from the soft plate to leave a vacant impression figured for radiation transmission in the soft plate along an axis. The impression is then closed to provide for radiation transmission along the axis of the impression. In the most common embodiment, two relatively soft plates having identical compositions with flat and highly polished initial surfaces are used. The impression(s) can be coated with reflective materials. Disclosure of an optical connector and emitter is included.

Abstract: There is provided a plane light source unit having a plane light pipe constituted by upper and lower surfaces and an incidence side surface which is one of side surfaces between the upper and lower surfaces, and a linear light pipe including a light supply surface. The linear light pipe has a refractive index higher than that of the plane light pipe. At least one point light source is disposed on the linear light pipe, and light incident from the at least one point light source is converted into light of a linear light source by the linear light pipe.

Abstract: A rod integrator includes a quadrangular prismatic light-guiding member with rectangular cross-sectional shape. The light-guiding member guides the beam from the first end surface to the second end surface opposing the first end surface while causing the beam to be reflected by the side surfaces such that the beam is outputted from the second end surface. The rod integrator includes a tube-shape body having the first open end portion tightly surrounding the end portion of the light-guiding member on the side of the second end surface, and having the second open end portion from which the beam is outputted while causing the beam from the first end portion to be reflected by inner mirror surfaces of the tube-shape body. The tube-shape body is arranged, in a pinwheel shape, a first, second, third, and fourth member, each of which is in plate shape and has a mirror surface on one side, onto the light-guiding member, such that the tube-shape body has the mirror surfaces facing inside thereof.

Abstract: A backlight unit for a display device includes a light guide panel comprising a plate-shaped body, at least one light guide projection for fitting the light guide panel disposed on left side or right side of the plate-shaped body, and a plurality of patterns formed on a lower surface of the plate-shaped body to uniformly project light. Upper and lower surfaces of the light guide projection are disposed remote as much as predetermined intervals, respectively from planes extended from upper and lower surfaces of the plate-shaped body. The light guide projection further includes an inclined surface on a side adjacent to a light source to prevent the light guide projections from cracking. Also, the light guide projection has at least one rounded or chamfered corner in order to efficiently prevent light concentration.

Abstract: A handheld computer system includes a housing, a processor coupled to the housing, a stylus coupled to the housing, and a light source coupled to the housing. The light source lights up the stylus.

Abstract: An illumination device including a light guide 22 surrounded by a protective sleeve 24. The light guide 22 is hollow and includes a cylindrical wall 26 having a structured outer surface 28 and a smooth inner surface 30. Light release structures are provided to reflect or refract light through the cylindrical wall 26 of the light guide 22. In certain embodiments, the protective sleeve is bonded to the light guide. Rigid fixtures can be used to retain the light guide in elastically deformed, non-cylindrical cross-sectional shapes.

Abstract: The present invention relates to a light guide capable of transferring light from an illuminating apparatus to a certain distant destination. The light guide includes a light source, and a hollow guide unit extended from the light source and having a transparent lateral surface. The present invention provides a pipe shaped light guide having a cross section of an epicycloidal curve for enhancing power and a light emitting characteristic. In the present invention, light is transmitted using a light transmitting material or a prism at a portion of a cross section of the epicycloidal curve, and a reflection plate formed of a high reflection ratio is installed at the remaining portions of the cross section of the same. In addition, an expensive lens or prism is not used in the present invention thereby decreasing fabrication cost. It is possible to provide a high efficiency light guide.

Abstract: An illumination device including a light guide 22 surrounded by a protective sleeve 24. The light guide 22 is hollow and includes a cylindrical wall 26 having a structured outer surface 28 and a smooth inner surface 30. Release structures are provided to reflect or refract light through the cylindrical wall 26 of the light guide 22.

Abstract: Disclosed is a microarray printing system and methods of printing probe microarrays. The system has a print head formed of one or more bundles of individual capillaries, such as light-guiding capillaries. The bundles may especially be random bundles of capillaries that provide a large number of probes on the surface of a substrate. Methods of registering or correlating the distal and proximal ends of the capillaries are also provided. Further, the invention provides methods and equipment for identifying defective microarrays that are missing one or more probes from the surface of the microarray.

Abstract: A light guide including a light guide body having a light re-directing side positioned opposite from a light output side. A plurality of elongate prisms are located adjacent the light output side of the light guide body. The prisms extend side-by-side relative to one another along lengths. The prisms include upper edges defining heights of the prisms. The upper edges extend along the lengths of the prisms. Each upper edge includes a plurality of edge segments having different magnitudes of slope. The light guide also includes a plurality of light extraction structures located adjacent the light re-directing side of the light guide body for reflecting light toward the light output side. The light extraction structures include elongated projections each having a plateau segment and first and second facets. The elongated projections are separated by lands that are recessed relative to the plateau segments. The first and second facets extend from the plateau segments to the lands.

Abstract: A light collimating film has a sheeting having a first side and a second side, wherein the first side includes a series of linear optical elements having a primary axis running the length of the optical elements, and the second side includes a plurality of subwavelength optical microstructures being oriented at about 90 degrees relative to the primary axis of the linear optical elements. Another embodiment includes a back lighting display device having a lighting device, a display panel, and a sheeting having a first side and a second side, wherein the first side includes a series of linear prisms having peaks, and the second side includes a plurality of subwavelength optical microstructures being oriented at about 90 degrees relative to the peaks of the linear prisms.

Abstract: An apparatus for adjusting the width of a coherent or partially coherent beam of light comprising at least one pair of opposing reflectors each having an inwardly facing light reflecting surface, the reflectors being pivotally mounted with respect to said optical axis and means for adjusting the angle of said pivotally mounted reflector with respect to said optical axis.

Abstract: An apparatus for positioning and adjusting a light pipe includes a bracket that is formed by folding a metallic plate. When the metallic plate is folded to form the bracket, a first end and a second end of the metallic plate perpendicularly press against each other to form a close space for accommodating the light pipe. The apparatus for positioning and adjusting a light pipe further includes a clip device for positioning the bracket. A first adjustment screw has a front end pressing against the side surface of the bracket. A second adjustment screw has a front end pressing against the bottom surface of the bracket. The horizontal position of the light pipe is modified by adjusting the first adjustment screw. The vertical position of the light pipe is modified by adjusting the second adjustment screw.

Abstract: An apparatus and method for illuminating a projection display which includes multiple light sources which are integrated through a multi-input ported light pipe disposed between the multiple lamps and the remainder of the projection display.

Abstract: A thin-profile, optically efficient lighting device for use with, among other things, flat information displays, includes a combination of three optically coupled light propagating structures, fabricated of electromagnetic flux transmitting materials. The first structure may be a generally elongated optical pipe adapted to receive light from at least one light source such as a light emitting diode. Radiation from additional sources is coupled into the first structure by a second structure which injects the radiation thereinto. Light injected into the first structure is directed into the third structure where it is redirected so that it propagates out of the third structure uniformly and efficiently and in a direction that is substantially perpendicular to the surface of the third structure. A device can include multiple bodies of any or all three structures.

Abstract: A light guiding plate, characterized by comprising a transparent thermoplastic resin composition containing 1-200 ppm of fine particles having a refractive index of 1.7-3.0 and an average particle diameter of 0.01-1.0 &mgr;m. This light guiding plate is suitable for display devices used in office automation apparatuses such as personal computers, word processors, etc. and various monitors displaying image signals such as panel monitors, television monitors, etc., display devices used in illuminators for indoor or outdoor space, and signs.

Abstract: An illuminated surgical retractor includes a handle having an elongated first blade portion connected at one end to one end of the handle and an elongated second blade portion extending along the length of the first blade portion. One end of the second blade portion defines an illumination input end to which a connector is coupled. The connector is shaped to optically couple the illumination input end to a source of illumination so that at least a portion of one of the first and second blade portions is illuminated.

Abstract: A light blender is described wherein light from a high intensity source such as a metal halide bulb can be conveyed through a flexible optical fiber cable for projection onto a remotely located site without uneven segments to uniformly illuminate the remote site. The optical light blender is of sufficient length so as to enable light from the light source to reach the end of the light blender with a large number of reflections from the wall of the light blender and thus produce blended light for uniform illumination.

Abstract: A monolithic element has a substrate body and at least one macro-optical characteristic integral in a first portion of the optical element. A plurality of surface micro-structures are integral in a portion of the optical element. The micro-structures are designed to homogenize light passing through the optical element to produce a predetermined pattern of smoothly varying, non-discontinuous light exiting the optical element. The light exiting the optical element is therefore altered according to both the macro-optical characteristic of the optical element as well as the homogenizing characteristics of the micro-structures.

Abstract: An optical transmission tube for illumination is uniquely incorporated into any one of a variety of automotive, commercial, retail, structural, architectural, safety, or other products including running boards, vehicle interior compartments such as a glove box, approximate the license plate attachment area on a vehicle, a trunk, a vehicle hood, on a vehicle door, a vehicle bumper, a vehicle luggage rack, a picture frame, a flashlight, a building, a guard rail, a construction barrier, a bicycle, a sign, an appliance interior compartment such as a refrigerator, a part bin, a retail display shelf, a clipboard, a step, a tractor trailer, a desk, a walkway, a room or storage chamber, a runway, an instrument panel, a railroad crossing gate, an emergency sign, an elevator doorway, a swimming pool, a dog collar, a fish tank, a baby crib a hand rail, an inline skate an island in a parking lot or on a street, affixed to a curb, or on safety clothing.

Abstract: Disclosed is a light pipe signaling device for signaling a user. A light pipe has a first end portion that fits into a receptacle. Both light pipe and receptacle are constructed using a transparent material. Light from a light source enters the receptacle and is transmitted to the light pipe. The light travels along a body of the light pipe to a second end portion. The second end portion is adapted to reflect or dissipate the light such that the user is able to see the light from a wide field of view. The light pipe is preferably removable and the receptacle is preferably incorporated into a device that activates the light source in order to alert the user.

Abstract: An optical device includes a plurality of lens plates spaced at specific intervals. At least one of the lens plates is provided with a lens array on at least one of its front and rear faces. The lens array is composed of a plurality of closely arranged lenses of a specific configuration. The lens array has at least one groove having a V-shaped cross-sectional configuration at a joint of adjacent lenses in at least one part of the lens array.

Abstract: There is provided a spread illuminating apparatus to ensure excellent light conductivity. A cover is integrally provided over a transparent substrate sandwiching a fluid (cushioning material) of a gel, liquid, or gaseous substance. With this structure, dust generated in assembly process is prohibited from getting on the transparent substrate, and even when other members or an assembly machine hit and bend the cover during the assembly process, the bending is absorbed by the fluid, and a light reflection pattern formed on the transparent substrate is protected against damages, whereby excellent light conductivity can be maintained.

Abstract: A projector includes a source of polychromatic light that propagates through color filter segments of a color wheel and enters an input aperture of an asymmetrical light integrating tunnel that integrates the filtered light into a uniform pattern at a nonrectangular output aperture of the tunnel. The uniform illumination exiting the nonrectangular output aperture is re-imaged onto a light valve that is mounted obliquely to a longitudinal axis of the tunnel. The image of the nonrectangular output aperture on the light valve compensates for any keystone distortion, illumination overfill and illumination drop-off regions on the light valve, thereby increasing brightness and brightness uniformity across the light valve. The asymmetrical light integrating tunnel may include a trapezoidal input aperture that reduces the time period when adjacent color wheel filter segments are traversing the input aperture, thereby increasing the time period when the input aperture receives light from each single filter segment.

Abstract: An illumination device that is relatively bright and uniform in appearance includes a light guide, which has a light guide core having an optically smooth surface for propagating light therethrough. A light emitting region, which extends along a portion of the core, includes at least one light extraction structure located along the optically smooth surface of the light guide core. The light extraction structure, which includes an optically reflective surface extending into the light guide core, is oriented to reflect light at an angle less than a critical angle necessary for light to propagate through the light guide core. A diffuse reflective material is disposed around at least a portion of the light guide. The diffuse reflective material directs at least a portion of the light reflected by the light extraction structure back through the light guide so that light is emitted through the light emitting region of the optically smooth surface.

Abstract: A light pipe is designed for a projector system. The light pipe gathers the light from a light source and guides the gathered light to an image device in the projector system. The area of the exit pupil of the light pipe is smaller than the area of the entrance pupil, and the shape of the exit pupil is scaled from that of the entrance pupil. This improves the light gathering efficiency of the light pipe.

Abstract: The invention discloses a solid rod dust-proof structure for projecting apparatuses. The solid rod includes an incident-beam surface and an outgoing-beam surface. The dust-proof structure includes: a housing provided with a first chamber and a second chamber connecting each other wherein the cross section of the second chamber is greater than that of the first chamber. The first chamber contains the solid rod, and a stopping portion is installed on the opposite end of the second chamber for stopping the solid rod; and a dust-proof plate being a transparent plate is contained in the second chamber to completely cover the outgoing-beam surface of the solid rod. Using the above structure, the outgoing-beam surface of the solid rod can be completely covered by the transparent dust-proof plate so that the structure is free from dust and the light transmitting through the outgoing-beam surface will not be blocked.

Abstract: An optical device for collecting light and selectively outputting or concentrating the light. A layer has an optical index of referaction n1, and top, bottom and side surfaces defining an angel of inclination &phgr;. A back surface spans the top, bottom and side surface. A first layer is coupled to the bottom surface of the layer and has an index of refraction n2. The first layer index n2 causes light input through the back surface of the layer to be preferentially output into the first layer. A second layer is coupled to the bottom of the first layer and selectively causes output of light into ambient. Additional layers, such as alight polarization layer, a polarization converting layer and a post LCD diffuser layer can be used to make preferential use of polarized light of diffuse light having passed through the LCD layer to enhance viewing of the output light.

Abstract: A lightguide having either a built-in prism sheet or a built-in diffuser sheet is disclosed. The lightguide includes: a prism sheet having a plane surface and a surface with a plurality of patterned microlens, a transparent wedge having a cross-section of trapezoid; and a binder layer sandwiched between said plane surface of said prism sheet and said transparent wedge. A method for manufacturing the lightguide is also disclosed here.

Abstract: A light collimating film has a sheeting having a first side and a second side, wherein the first side includes a series of prisms, and the second side includes a plurality of subwavelength optical microstructures. Another embodiment includes a back lighting display device having a lighting means, a display panel, and a sheeting having a first side and a second side, wherein the first side includes a series of prisms, and the second side includes a plurality of subwavelength optical microstructures. A preferred embodiment includes a back lighting display device having a first collimating film having a first surface with a subwavelength optical microstructure thereon and a second surface with linear prisms having an included angle of greater than about 95 degrees, and a second collimating film having a first surface with a subwavelength optical microstructure thereon and a second surface with linear prisms having an included angle of less than about 85 degrees.

Abstract: A light tunnel apparatus (200 or 300) having an output end (56 or 98), for uniformizing light (L) that travels through a light tunnel (30 or 80). The apparatus comprises a light tunnel having first and second sides (36, 40 or 86, 90), and one or more AO modulators (210 or 310) respectively arranged on at least one of the first and second sides. The AO modulators are arranged such that activating the one or more of them causes at least one of the first and second sides to be displaced. This displacement changes the path of light traveling through the light tunnel by an amount sufficient to reduce illumination non-uniformities at the output end. The light tunnel may be a hollow light tunnel (30) with reflective inner surfaces, or a solid light tunnel (80) with a refractive index. A method of uniformizing illumination using a light tunnel is also disclosed.

Abstract: A folded light tunnel apparatus and method of providing light with a high degree of spatial uniformity in a compact arrangement. The light tunnel (100, 190, 300, 350) comprises plurality of prisms (110, 310) having a different cross-sectional dimension (W) and at least one beveled end (110E) having a corresponding beveled end face (110F) through which light reflected by the beveled end passes. The plurality of prisms are arranged adjacent one another in a either two-dimensional or three dimensional stack, with each beveled end face arranged adjacent another beveled end face such that light reflected from one beveled end is received by said adjacent beveled end face and coupled into the adjacent prism. The width of the prisms is governed by a scaling factor (K or K′) that depends on whether the prism stack is two-dimensional or three-dimensional. Designing the light tunnel according to the scaling factor allows for the light tunnel to be theoretically 100% efficient in the transmission of light.

Abstract: A monolithic element has a substrate body and at least one macro-optical characteristic integral in a first portion of the optical element. A plurality of surface micro-structures are integral in a portion of the optical element. The micro-structures are designed to homogenize light passing through the optical element to produce a predetermined pattern of smoothly varying, non-discontinuous light exiting the optical element. The light exiting the optical element is therefore altered according to both the macro-optical characteristic of the optical element as well as the homogenizing characteristics of the micro-structures.

Abstract: A non-scattering light pipe includes a transition surface between a first side wall and an input surface and a second side wall and the input surface. The transition surface is arranged to substantially obscure the corner interfaces between the first and second side walls and the input surface such that in the corner formation any imperfections therein are not imaged into the output. Most preferably, the transition surface is optimized to provide a substantially uniform light intensity distribution. A light pipe in accordance with the preferred embodiments of the present invention is further arranged to couple to a linear light source, such as a cold cathode fluorescent light (CCFL). The light source is arranged such that dim areas, i.e., areas of the light source having non-uniform intensity, are not disposed adjacent the input surface.

Abstract: A light guide luminaire includes a longitudinal housing having a center and an inner surface, and a light guide formed of at least two sections of optical lighting film arranged within the housing such that the shortest distance between the center of the housing and the inner surface of the housing is smaller than the radius of curvature of each section of optical lighting film. The light guide is slidably retained within the housing, and the housing and optical lighting film are arranged to define air gaps between the housing and optical lighting film. The luminaire may also include an extractor element extending radially inwardly from the inner surface of the housing for scattering light, and a back reflector for reflecting light back into the light guide. A joint member adapted to slidably receive end portions of the optical lighting film sections, the back reflector sections, and an extractor element is also disclosed.

Abstract: A monolithic element has a substrate body and at least one macro-optical characteristic integral in a first portion of the optical element. A plurality of surface micro-structures are integral in a portion of the optical element. The micro-structures are designed to homogenize light passing through the optical element to produce a predetermined pattern of smoothly varying, non-discontinuous light exiting the optical element. The light exiting the optical element is therefore altered according to both the macro-optical characteristic of the optical element as well as the homogenizing characteristics of the micro-structures.

Abstract: An injection molded light pipe having a sharp curve is proposed, wherein the injection molding mark is on the inside surface of the sharp curve. The light pipe has a 180° curve with a radius of curvature less than approximately 3 times the diameter of the light pipe.

Abstract: A light transmission tube includes a tubular clad and a core section having a higher refractive index than that of the tubular clad, said light transmission tube is characterized in that a belt-like reflecting layer is formed between the tubular clad and the core section, extending in the longitudinal direction of the tubular clad, in a manner such that a light passing through the core section is reflected and scatterred by the reflecting layer and then emitted from an outer surface area of the tubular clad, which outer surface area is located opposite to one side of the tubular clad where the reflecting layer has been formed. Further, the reflecting layer may be so formed that a light is allowed to be emitted in a plurality of directions. Moreover, the belt-like reflecting layer may be formed into a spiral configuration. The width of the belt-like reflecting layer may be changed in the longitudinal direction of the light transmission tube. The tubular clad is allowed to have a non-circular cross section.

Abstract: A monolithic element has a substrate body and at least one macro-optical characteristic integral in a first portion of the optical element. A plurality of surface micro-structures are integral in a portion of the optical element. The micro-structures are designed to homogenize light passing through the optical element to produce a predetermined pattern of smoothly varying, non-discontinuous light exiting the optical element. The light exiting the optical element is therefore altered according to both the macro-optical characteristic of the optical element as well as the homogenizing characteristics of the micro-structures.

Abstract: There is provided a plane light source unit having a plane light pipe constituted by upper and lower surfaces and an incidence side surface which is one of side surfaces between the upper and lower surfaces, and a linear light pipe including a light supply surface and having a refractive index higher than that of the plane light pipe. At least one point light source is disposed on the linear light pipe, and light incident from the at least one point light source is converted into light of a linear light source by the linear light pipe. The linear light pipe is disposed so as to make the light supply surface of the linear light pipe face the incidence side surface of the plane light pipe, and light of the linear light source exiting from the light supply surface so as to be incident on the incidence side surface is converted into light of a plane light source by means of the plane light pipe.

Abstract: A transparent lightguide (3) which guide light at least from one side end plane is characterized in that a large number of speckled, solid-line shaped or broken-line shaped protruding patterns whose cross-sectional width W (&mgr;m) at a cross section perpendicular to the axis of a linear light source is 10≦W≦200 are arranged on a light emitting surface at a low density in a region close to the linear light source and at a high density in a region far from the linear light source so as to make the luminance distribution of the light emitted from the light emitting surface approximately uniform. Here, the cross section of the protruding pattern is preferable to be approximately trapezoidal while having a straight part partially and the ratio H/W to be 0.2≦H/W≦1.0, where W and H denote cross-sectional width and height of the protruding pattern, respectively, or the cross section of the protruding pattern is preferable to be approximately circular-arc and the ratio H/W to be 0.2≦H/W≦0.

Abstract: An illumination system having a hollow waveguide including first and second light directing arrays (LDA), each having a plurality of generally lenticular prisms defined thereon and arranged generally orthogonally with respect to each other. Light rays from a light source enter the waveguide through a light input side and emerge from the waveguide through a light output side at a predetermined flux and angular distribution. The light output flux and angular distribution can each be independently controlled in accordance with the present invention by the LDAs to provide an illumination system that can be configured for various light output distribution and intensity requirements.

Abstract: A protective cover for protecting a lighting device from direct contact with contaminants or components which may interfere with proper operation thereof. The contaminant (e.g., blood, body tissue, dirt, oil, grease, paint, etc.) or other component (e.g., adhesive pad) can interfere with the desired internal reflection of the light propogating through a light transmitting member, by changing the angle of reflection of the propagating light. The result is that optical energy is absorbed by the contaminant or component and converted to heat, thus causing the contaminant or component to quickly rise to an undesirable temperature. The present invention protects a lighting device from such interference, while maintaining its versatility.

Abstract: An optical device includes a light transmitting non-linear optical material having a first face and a second face. The first and second faces oppose each other. The first face has a plurality of first reflecting portions provided thereon, and the second face has a plurality of second reflecting portions provided thereon. Each of the second reflecting portions corresponds to one of the first reflecting portions. Furthermore, the first and second faces are substantially flat except for at least one convex arcuate portion being formed on at least one of the first and second faces. Additionally, at least one of the first and second reflecting portions is obtained by coating a reflective material on the convex arcuate portion.

Abstract: A vision system is provided which allows viewing and/or inspection of an end surface of an optical fiber through a bulkhead on a backplane of a rack. By placing such a vision system on a mount configured to be inserted in the rack, the use of such a vision system does not require the rack design be modified or that other modules be removed. Preferably an adapter for mating the vision system with the bulkhead may be moved to position the adapter relative to the bulkhead housing the fiber of interest.

Abstract: Illumination devices and light distribution systems utilizing overlapping joints, connector rings, end caps, assemblies for mounting light tubes to a ceiling or wall, and protective tubes.

Abstract: An angled illumination tube is capable of reducing a dark spot behind the reflector, while illuminating the tube uniformly over the length of the tube. The tube is used in combination with a light source providing a light beam and comprises an angled transparent tubular conduit having a first end and a second end on opposite longitudinal ends of the conduit. The conduit has a bend between the first and second longitudinal ends, and is used with the first end receiving the light beam from the light source in order to guide the light beam along the length of the conduit. A reflector is disposed within the bend to reflect the light beam from the first end to direct a reflected light beam towards the second end. The reflector defines an incident light axis along which the light beam is guided to the reflector, and a reflected light axis along which the reflected light beam is directed to said second end.

Abstract: A coherent illuminator system and method wherein an incident energy beam is directed at an end of image conduit rotating around its axis. The incident energy beam may be generated by a laser, maser, or similar radiation source. A substantially cylindrically uniform radiation spot is obtained from the other end of the image conduit, which may be guided by waveguide means to an application element such as, for example, an emission microscope or a medical instrument.

Abstract: A light regulator and a surface light source device employing the light regulator. For liquid-crystal display applications, the surface light source device can effectively prevent degradation in the quality of the emitted light and can reliably provide the required directivity correction. The light regulator is formed by laminatedly arranging a light scattering surface between first and second sheet-like members. The two sheet-like members mutually differ in shape, material and refractive index. Scattering means arranged between the first and second sheet-like members prevents Newton's rings due to spaces between the two sheet-like members from occurring. A light diffusion sheet may be disposed between the first and second sheet-like members.