Partial mirror, optical waveguide construction, and optical system

Abstract

An optical waveguide construction includes an optical core configured to propagate an image light primarily by total internal reflection. An incident first angle of the propagating image light on a first major surface of the optical core is greater than a critical angle. The optical waveguide includes a plurality of partial mirrors embedded in the optical core. The image light is incident on each first plurality of light extracting partial mirrors in the plurality of partial mirrors at an incident third angle and each second plurality of light transmitting partial mirrors in the plurality of partial mirrors at an incident fourth angle less than the third angle by at least 15 degrees. Each light extracting partial mirror extracts at least a portion of the propagating image light incident on the light extracting partial mirror toward a viewer configured to view an object in a real-world scene through the partial mirrors.

Description

PA103196W002PARTIAL MIRROR, OPTICAL WAVEGUIDE CONSTRUCTION, AND OPTICAL SYSTEMTechnical Field

[0001] The present disclosure relates to a partial mirror, an optical waveguide construction, and an optical system including the optical waveguide construction.Background

[0002] Typically, optical systems in applications, such as augmented reality (AR), have become increasingly prevalent, offering a viewer an ability to see images generated by a display of the optical systems overlaid onto a real world. Some of these optical systems, include optical waveguides including reflectors. However, the optical waveguides including reflectors may have a complex manufacturing process and may be costly. Further, the reflectors of such optical waveguides may require having optical properties that may be difficult to achieve.Summary

[0003] In a first aspect, the present disclosure provides an optical waveguide construction. The optical waveguide construction includes an optical core configured to propagate an image light along an in-plane first direction primarily by total internal reflection, such that an incident first angle of the propagating image light on a first major surface of the optical core is greater than a critical angle. The optical waveguide construction further includes a plurality of substantially parallel spaced apart partial mirrors embedded in the optical core. The partial mirrors are arranged along the first direction and extend along substantially a same in-plane orthogonal second direction. Each of the partial mirrors makes an oblique second angle with the first major surface. The image light is incident on each of a first plurality of light extracting partial mirrors in the plurality of partial mirrors at an incident third angle. Further, the image light is incident on each of a second plurality of light transmitting partial mirrors in the plurality of partial mirrors at an incident fourth angle less than the third angle by at least 15 degrees. Each of the light extracting partial mirrors extracts at least a portion of the propagating image light that is incident on the light extracting partial mirror toward a viewer. The viewer is configured to view an object in a real-world scene through the partial mirrors. For a substantially collimated light incident from within the optical core, for at least one of mutually orthogonal first and second polarization states, and for a visible wavelength range extending from about 420 nanometers (nm) to about 680 nm, each of the partial mirrors has an average optical reflectance of greater than about 10% and an average optical transmittance of greater than about 40% when the incident light is incident at each of the second and third angles. For the substantially collimated light incident from within the optical core, for the at least one of mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors has anaverage optical reflectance of less than about 20% and an average optical transmittance of greater than about 40% when the incident light is incident at the fourth angle.

[0004] In a second aspect, the present disclosure provides an optical system. The optical system includes the optical waveguide construction of the first aspect. The optical system further includes a display configured to form and emit an image. Image lights from the emitted image enter the optical core and include the image light propagating along the in-plane first-direction primarily by total internal reflection.

[0005] In a third aspect, the present disclosure provides a partial mirror. The partial mirror includes a plurality of polymeric layers numbering between about 100 and 400 in total. Each of the polymeric layers has an average thickness of less than about 500 nm. A maximum difference between indices of refraction of the polymeric layers along each of mutually orthogonal in-plane first and second directions and a normal direction orthogonal to the first and second directions is less than about 0.05. When the partial mirror is disposed in a medium having an index of refraction of greater than about 1.3 and a substantially collimated light is incident on the partial mirror from within the medium, then for each first incident angle of less than at least about 20 degrees, for at least one of mutually orthogonal first and second polarization states, and for each of a blue wavelength range extending from about 455 nm to about 475 nm, a green wavelength range extending from about 520 nm to about 540 nm, and a red wavelength range extending from about 615 nm to about 635 nm, the partial mirror has a first average optical reflectance. The first average optical reflectances for all the first incident angles, the at least one of the first and second polarization states, and the blue, green, and red wavelength ranges have a combined average Ravg and a combined standard deviation Rst. The combined average Ravg is less than or equal to about 10%, i.e., Ravg < 10%. Further, a ratio between the combined standard deviation Rst and the combined average Ravg is less than or equal to about 0.25, i.e., Rst / Ravg < 0.25. For at least one second incident angle of greater than about 40 degrees and for a visible wavelength range extending from about 420 nm to about 680 nm, the partial mirror has an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40%.

[0006] In a fourth aspect, the present disclosure provides a partial mirror. The partial mirror includes a plurality of polymeric layers numbering between about 100 and 400 in total. Each of the polymeric layers has an average thickness of less than about 500 nm. A maximum difference between indices of refraction of the polymeric layers along each of mutually orthogonal in-plane first and second directions and a normal direction orthogonal to the first and second directions is less than about 0.05. When the partial mirror is disposed in a medium having an index of refraction of greater than about 1.3, and a substantially collimated unpolarized light is incident on the partial mirror from within the medium, then for a visible wavelength range extending from about 420 nm to about 680 nm, and for sequentially increasing first through fourth incident angles, where the first incident angle is less than about 10 degrees, and where the second through the fourth incident angles are greater thanthe first incident angle by at least 30 degrees, are less than about 80 degrees, and are spaced apart by at least 5 degrees, the partial mirror has respective average optical reflectances Ravgl through Ravg4 and respective standard deviations Rstdl through Rstd4. Ravi is less than about 10%. Rav3 is greater than about 10% and less than about 35%. Each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than each of Rstd2 / Ravg2 and Rstd3 / Ravg3 by at least a factor of 2.

[0007] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.Brief Description of the Drawings

[0008] Exemplary embodiments disclosed herein may be more completely understood in consideration of the following detailed description in connection with the following figures. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

[0009] FIG. 1 shows a schematic sectional view of an optical waveguide construction, according to an embodiment of the present disclosure;

[0010] FIG. 2 shows a schematic sectional view of an optical system, according to an embodiment of the present disclosure;

[0011] FIG. 3 A shows a schematic sectional view of an optical system, according to another embodiment of the present disclosure;

[0012] FIG. 3B shows a schematic sectional view of an optical system, according to another embodiment of the present disclosure;

[0013] FIG. 4 shows a detailed schematic view of one of a plurality of partial mirrors, according to an embodiment of the present disclosure;

[0014] FIG. 5 A shows a plot depicting a thickness of polymeric layers as a function of a number of the polymeric layer, according to an embodiment of the present disclosure;

[0015] FIG. 5B shows a magnified plot depicting the thickness of the polymeric layers as the function of the number of the polymeric layer, according to an embodiment of the present disclosure;

[0016] FIG. 6 shows a schematic view of an optical core including the plurality of partial mirrors, according to an embodiment of the present disclosure;

[0017] FIG. 7 shows a schematic top view of the optical core, according to an embodiment of the present disclosure;

[0018] FIG. 8A shows a graph depicting an optical reflectance versus wavelength of the partial mirrors for first and second polarization states, according to an embodiment of the present disclosure;

[0019] FIG. 8B shows a graph depicting an optical reflectance versus wavelength of the partial mirrors for the first and second polarization states, according to another embodiment of the present disclosure;

[0020] FIG. 9A shows a graph depicting an average optical reflectance versus incident angles of the partial mirrors for the first and second polarization states, according to an embodiment of the present disclosure;

[0021] FIG. 9B shows a graph depicting an average optical reflectance versus incident angles of the partial mirrors for the first and second polarization states, according to another embodiment of the present disclosure; and

[0022] FIG. 10 shows a graph depicting an optical reflectance versus wavelength of the partial mirrors for a substantially collimated unpolarized light, according to an embodiment of the present disclosure.Detailed Description

[0023] In the following description, reference is made to the accompanying figures that form a part thereof and in which various embodiments are shown by way of illustration. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0024] In the following disclosure, the following definitions are adopted.

[0025] As used herein, all numbers should be considered modified by the term “about”. As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably.

[0026] As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties).

[0027] The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0028] The term “about”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 5% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0029] As used herein, the terms “first” and “second” are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure. The terms “first” and “second” when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.

[0030] As used herein, “at least one of A and B” should be understood to mean “only A, only B, or both A and B”.

[0031] Typically, optical systems in applications, such as augmented reality (AR), have become increasingly prevalent, offering a viewer an ability to see images generated by a display of the optical systems overlaid onto a real world. Some of these optical systems, include optical waveguides including reflectors. However, the optical waveguides including reflectors may have a complex manufacturing process and may be costly. Further, the reflectors of such optical waveguides may require having optical properties that may be difficult to achieve.

[0032] The present disclosure relates to an optical waveguide construction. The optical waveguide construction includes an optical core configured to propagate an image light along an inplane first direction primarily by total internal reflection, such that an incident first angle of the propagating image light on a first major surface of the optical core is greater than a critical angle. The optical waveguide construction further includes a plurality of substantially parallel spaced apart partial mirrors embedded in the optical core. The partial mirrors are arranged along the first direction and extend along substantially a same in-plane orthogonal second direction. Each of the partial mirrors makes an oblique second angle with the first major surface. The image light is incident on each of a first plurality of light extracting partial mirrors in the plurality of partial mirrors at an incident third angle. Further, the image light is incident on each of a second plurality of light transmitting partial mirrors in the plurality of partial mirrors at an incident fourth angle less than the third angle by at least 15 degrees. Each of the light extracting partial mirrors extracts at least a portion of the propagating image light that is incident on the light extracting partial mirror toward a viewer. The viewer is configured to view an object in a real-world scene through the partial mirrors. For a substantially collimated light incident from within the optical core, for at least one of mutually orthogonal first and second polarization states, and for a visible wavelength range extending from about 420 nanometers (nm) to about 680 nm, each of the partial mirrors has an average optical reflectance of greater than about 10% and an average optical transmittance of greater than about 40% when the incident light is incident at each of the second and third angles. For the substantially collimated light incident from within the optical core, for the at least one of mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors has an average optical reflectance of less than about 20% and an average optical transmittance of greater than about 40% when the incident light is incident at the fourth angle.

[0033] Therefore, for the substantially collimated light incident from within the optical core, for at least one of mutually orthogonal first and second polarization states, and for the visible wavelength range, the partial mirrors may achieve the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light is incident on the first plurality of light extracting partial mirrors and the average optical reflectance of less than about 20% and the average optical transmittance of greater than about 40% when the incident light isincident on the second plurality of light transmitting partial mirrors. In other words, the optical waveguide construction of the present disclosure may maximize an optical transmission or minimize an optical reflection at lower angles (i.e., the fourth angle) and may maximize an optical transmission at higher angles (i.e., the second angle and third angles).

[0034] Maximizing the optical transmission or minimizing the optical reflection at the lower angles (i.e., the fourth angle) may further prevent trapping of the image light, which may otherwise reduce an efficiency of the optical waveguide construction.

[0035] Referring now to figures, FIG. 1 shows a schematic sectional view of an optical waveguide construction 300, according to an embodiment of the present disclosure.

[0036] A coordinate system including mutually perpendicular x, y, and z-axes is also illustrated in FIG. 1. The x and y-axes are in-plane axes of the optical waveguide construction 300, while the z- axis is a transverse axis disposed along a thickness of the optical waveguide construction 300. In other words, the x and y-axes are along a plane of the optical waveguide construction 300 defining a x-y plane, and the z-axis is perpendicular to the x-y plane of the optical waveguide construction 300.

[0037] The optical waveguide construction 300 includes an optical core 10 configured to propagate an image light 20 along an in-plane first direction primarily by total internal reflection such that, an incident first angle al of the propagating image light 20 on a first major surface 11 of the optical core 10 is greater than a critical angle. In some embodiments, the in-plane first direction may be substantially along the x-axis. In some embodiments, the optical core 10 further includes a second major surface 13 opposite to the first major surface 11.

[0038] In some embodiments, the first angle al is between about 30 degrees and 70 degrees. In some embodiments, the first angle al is between about 35 degrees and 65 degrees, between about 35 degrees and 60 degrees, between about 40 degrees and 60 degrees, or between about 45 degrees and 60 degrees.

[0039] In some embodiments, the optical core 10 includes one or more of an organic and an inorganic materials. In some embodiments, the optical core 10 includes one or more of a glass and polymer.

[0040] In some embodiments, the optical core 10 has a refractive index (interchangeably referred to as “the index of refraction of the optical core 10, herein”) of between about 1.3 and about 2.5 for at least one visible wavelength in a visible wavelength range extending from about 420 nm to about 680 nm. In some embodiments, the optical core 10 has the refractive index of between about 1.4 and about 2.2, between about 1.5 and about 2, or between about 1.5 and about 1.8 for the at least one visible wavelength in the visible wavelength range.

[0041] In some embodiments, the optical waveguide construction 300 includes an optical buffer 12 disposed on and covering at least the first major surface 11 of the optical core 10. In some embodiments, the at least the first major surface 11 of the optical core 10 includes the first major surface 11 and the opposite second major surface 13 of the optical core 10. In some embodiments, theoptical buffer 12 has an index of refraction less than the index of refraction of the optical core 10 for the at least one visible wavelength in the visible wavelength range. The optical buffer 12 may ensure that the image light 20 propagates along the first direction by total internal reflection.

[0042] The optical waveguide construction 300 further includes a plurality of substantially parallel spaced apart partial mirrors 30 embedded in the optical core 10. In some embodiments, the plurality of substantially parallel spaced apart partial mirrors 30 may be interchangeably referred to as “the plurality of partial mirrors 30” or “the partial mirrors 30” herein.

[0043] In some embodiments, the plurality of partial mirrors 30 is embedded and spaced apart in the optical core 10. In some embodiments, the partial mirror 30 is disposed in a medium having an index of refraction of greater than about 1.3. In some embodiments, the partial mirror 30 is disposed in the medium having the index of refraction of greater than about 1.4, greater than about 1.5, greater than about 1.6, greater than about 1.7, or greater than about 1.8. In some embodiments, the index of refraction of the medium is less than about 2.5. In some embodiments, the index of refraction of the medium is less than about 2.2, less than about 2, or less than about 1.8.

[0044] In some embodiments, the optical core 10 includes the medium. In some embodiments, the optical core 10 includes the index of refraction that is substantially equal to the index of refraction of the medium.

[0045] With reference to FIG. 1, a coordinate system including mutually perpendicular x’, y’, and z’-axes is also illustrated. The x’ and y’-axes are in-plane axes of the partial mirrors 30 of the optical waveguide construction 300, while the z’-axis is a transverse axis disposed along a thickness of the partial mirrors 30. In other words, the x’ and y’-axes are along a plane of the partial mirrors 30 defining a x’-y’ plane, and the z’-axis is perpendicular to the x’-y’ plane of the partial mirrors 30.

[0046] The partial mirrors 30 are arranged along the first direction (i.e., substantially along the x- axis) and extend along substantially a same in-plane orthogonal second direction. In some embodiments, the same in-plane orthogonal second direction may be substantially along the y-axis.

[0047] Each of the partial mirrors 30 make an oblique second angle a2 with the first major surface 11. In some embodiments, the second angle a2 is greater about 30 degrees. In some embodiments, the second angle a2 is greater than about 35 degrees, greater than about 40 degrees, greater than about 45 degrees, greater than about 50 degrees, greater than about 55 degrees, or greater than about 60 degrees. In some embodiments, the oblique second angle a2 is about 60 degrees.

[0048] The image light 20 is incident on each of a first plurality of light extracting partial mirrors 30a in the plurality of partial mirrors 30 at an incident third angle a3 and the image light 20 is incident on each of a second plurality of light transmitting partial mirrors 30b in the plurality of partial mirrors 30 at an incident fourth angle a4 less than the third angle a3 by at least 15 degrees.

[0049] In some embodiments, the fourth angle a4 is less than the third angle a3 by at least 20 degrees, at least 25 degrees, at least 30 degrees, at least 35 degrees, at least 40 degrees, at least 45 degrees, at least 50 degrees, at least 55 degrees, or by at least 60 degrees.

[0050] In some embodiments, the third angle a3 is about 60 degrees and the fourth angle a4 is about 0 degree. Therefore, in some embodiments, the fourth angle a4 is less than the third angle a3 by about 60 degrees.

[0051] In some embodiments, the third angle a3 is greater than about 30 degrees. In some embodiments, the third angle a3 is greater than about 35 degrees, greater than about 40 degrees, greater than about 45 degrees, greater than about 50 degrees, greater than about 55 degrees, or greater than about 60 degrees.

[0052] In some embodiments, the second and third angles a2, a3 are within about 15 degrees of each other. In some embodiments, the second and third angles a2, a3 are within about 10 degrees, or within about 5 degrees of each other. In some embodiments, the second and third angles a2, a3 are within about 0 degree of each other.

[0053] In some embodiments, the fourth angle a4 is less than about 15 degrees. In some embodiments, the fourth angle a4 is less than about 10 degrees, less than about 7 degrees, less than about 5 degrees, less than about 4 degrees, less than about 3 degrees, less than about 2 degrees, or less than about 1 degree. As discussed above, in some embodiments, the fourth angle a4 is about 0 degree.

[0054] Each of the light extracting partial mirrors 30a, i.e., the first plurality of light extracting partial mirrors 30a, extracts at least a portion 21 of the propagating image light 20 that is incident on the light extracting partial mirror 30a toward a viewer 50. The viewer 50 is configured to view an object 61 in a real-world scene 60 through the partial mirrors 30.

[0055] In some embodiments, the propagating image light 20 that is incident on the light extracting partial mirror 30a may be referred to as “the incident propagating image light 22”.

[0056] FIG. 2 shows a schematic sectional view of an optical system 400, according to an embodiment of the present disclosure. In some embodiments, the optical system 400 includes the optical waveguide construction 300.

[0057] In some embodiments, the optical system 400 further includes a display 70 configured to form and emit an image 71. In some embodiments, image lights 72 from the emitted image 71 enter the optical core 10 and include the image light 20 propagating along the in-plane first direction primarily by total internal reflection. In some embodiments, the emitted image 71 enters the optical core 10 through a minor side surface 14 of the optical core 10.

[0058] FIG. 3A shows a schematic sectional view of an optical system 401, according to another embodiment of the present disclosure.

[0059] The optical system 401 is substantially similar to the optical system 400 of FIG. 2. However, in the illustrated embodiment of FIG. 3 A, the emitted image 71 enters the optical core 10 through a grating coupler 80 disposed on or in the optical core 10. Specifically, in the illustrated embodiment of FIG. 3A, the grating coupler 80 is formed on the first major surface 11 of the optical core 10.

[0060] FIG. 3B shows a schematic sectional view of an optical system 402, according to another embodiment of the present disclosure.

[0061] The optical system 402 is substantially similar to the optical system 400 of FIG. 2. However, in the illustrated embodiment of FIG. 3B, the emitted image 71 enters the optical core 10 through a prism coupler 81 disposed on or in the optical core 10. Specifically, in the illustrated embodiment of FIG. 3B, the prism coupler 81 is placed on the first major surface 11 of the optical core 10.

[0062] FIG. 4 shows a detailed schematic view of one of the partial mirrors 30, according to an embodiment of the present disclosure.

[0063] Each of the partial mirrors 30 includes the plurality of polymeric layers 35 numbering between about 50 and 700 in total. In some embodiments, each of the partial mirror 30 includes the plurality of polymeric layers 35 numbering between about 100 and 400 in total. In some embodiments, each of the partial mirror 30 includes the plurality of polymeric layers 35 numbering between about 150 and 350 or between about 200 and 300 in total. In some embodiments, the partial mirror 30 includes the plurality of polymeric layers 35 numbering about 225 in total.

[0064] In some embodiments, the plurality of polymeric layers 35 includes a plurality of alternating first and second polymeric layers 31, 32. In other words, each of the partial mirrors 30 includes the plurality of alternating first and second polymeric layers 31, 32. In some embodiments, each of the partial mirror 30 includes the plurality of alternating first and second polymeric layers 31, 32 numbering between about 100 and 600, between about 150 and 500, between about 150 and 450, between about 150 and 400, between about 200 and 350, or between about 200 and 300 in total.

[0065] Each of the polymeric layers 35 has an average thickness t of less of than about 500 nanometers (nm). In other words, each of the first and second polymeric layers 31, 32 has the average thickness t of less of than about 500 nm. The term “average thickness t”, as used herein, refers to an average of thicknesses measured at multiple points across a plane (i.e., the x’-y’ plane) of each of the polymeric layers 35.

[0066] In some embodiments, each of the polymeric layers 35 has the average thickness t of less than about 450 nm, less than about 400 nm, less than about 350 nm, less than about 300 nm, or less than about 250 nm. In some embodiments, each of the polymeric layers 35 has the average thickness t of between about 60 nm and 260 nm.

[0067] In some embodiments, each of the partial mirrors 30 includes at least one skin layer 33 having an average thickness st of greater than about 500 nm. The term “average thickness st”, as used herein, refers to an average of thicknesses measured at multiple points across a plane (i.e., the x’-y’ plane) of each of the at least one skin layer 33. Furthermore, in some embodiments, the thickness direction extends substantially along the z’-axis. The at least one skin layer 33 may protect the plurality of polymeric layers 35 and may also provide mechanical stability to the partial mirror 30. In some cases, the at least one skin layer 33 may act as a protective boundary layer (PBL).

[0068] In some embodiments, for each pair of adjacent first and second polymeric layers 31, 32 in the plurality of first and second polymeric layers 31, 32, the first and second polymeric layers 31, 32 have respective indices of refraction nix and n2x along an in-plane first direction, nly and n2y along an in-plane orthogonal second direction, and nlz and n2z along a third direction orthogonal to the first and second directions, such that for at least one visible wavelength in the visible wavelength range, a magnitude of each of nlx-n2x, nly-n2y, and nlz-n2z is less than about 0.05.

[0069] In some embodiments, the magnitude of each of nlx-n2x, nly-n2y, and nlz-n2z is less than about 0.045, less than about 0.040, less than about 0.035, less than about 0.03, less than about 0.025, or less than about 0.02. For example, the magnitude of nlx-n2x is 0.030, the magnitude of nly-n2y is 0.030, and the magnitude of nlz-n2z is 0.020.

[0070] A maximum difference between the indices of refraction of the polymeric layers 35 along each of the mutually orthogonal in-plane first and second directions and the normal direction orthogonal to the first and second directions is less than about 0.05.

[0071] In some embodiments, the maximum difference between the indices of refraction of the polymeric layers 35 along each of the mutually orthogonal in-plane first and second directions and the normal direction orthogonal to the first and second directions is less than about 0.045, less than about 0.040, less than about 0.035, less than about 0.03, less than about 0.025, or less than about 0.02.

[0072] In some embodiments, the in-plane first direction may be substantially along the x’-axis, the in-plane orthogonal second direction may be substantially along the y’-axis, and the third direction orthogonal to the first and second directions may be substantially along the z’-axis.

[0073] In some embodiments, the magnitude of nlz-n2z is greater than about 0.005. In some embodiments, the magnitude of nlz-n2z is greater than about 0.01, greater than about 0.015, or greater than about 0.02. In some embodiments, the magnitude of nlz-n2z is less than the magnitude of each of nlx-n2x and nly-n2y.

[0074] In some embodiments, one of the first polymeric layers 31 and the second polymeric layers 32 (e.g., the first polymeric layers 31) include polyethylene terephthalate (PET) and may have a high index. In some embodiments, the other of the first polymeric layers 31 and the second polymeric layers 32 (e.g., the second polymeric layers 32) include glycol-modified polyethylene terephthalate (PETg) or a blend of the PET / PETg and may have a low index. In some embodiments, the at least one skin layer 33 includes PETg.

[0075] In some embodiments, the partial mirrors 30 may include an optical film OF1. In some embodiments, the partial mirrors 30 may include an optical film OF2.

[0076] Table 1 provided below summarizes the index of refraction of the plurality of first and second polymeric layers 31, 32 of the optical film OF1. Table 1 also summarizes the magnitudes nlx- n2x, nly-n2y, and nlz-n2z for the optical film OF1.Table 1

[0077] Table 2 provided below summarizes the index of refraction of the plurality of first and second polymeric layers 31, 32 of the optical film OF2. Table 2 also summarizes the magnitudes nlx- n2x, nly-n2y, and nlz-n2z for the optical film OF2.Table 2

[0078] FIG. 4 further illustrates a substantially collimated light 40 incident on the partial mirror 30 at an incident angle bl.

[0079] FIG. 5 A shows a plot 900 depicting a thickness of the polymeric layer 35 (shown in FIG.4) as a function of the number of the polymeric layer 35, according to an embodiment of the present disclosure. FIG. 5B shows a magnified plot 910 depicting the thickness of the polymeric layer 35 as the function of the number of the polymeric layer 35, according to an embodiment of the present disclosure.

[0080] The thickness of the polymeric layer 35 is expressed in nanometers (nm) in the ordinate. The number of the polymeric layer 35 is expressed in the abscissa.

[0081] Referring to FIGS. 4, 5A, and 5B, as discussed above, in some embodiments, the plurality of polymeric layers 35 includes the plurality of alternating first and second polymeric layers 31, 32.

[0082] In some embodiments, when the first polymeric layers 31 or the second polymeric layers 32 are sequentially numbered, then the plot 900, 910 of the thickness of the polymeric layer 35 as the function of the number of the polymeric layer 35 has a non-linear profile.

[0083] The plots 900, 910 include a curve OF1LT depicting the thickness of the polymeric layer 35 of the optical film OF1 as the function of the number of the polymeric layer 35. The plots 900,910 further include a curve OF2LT depicting the thickness of the polymeric layer 35 of the optical film OF2 as the function of the number of the polymeric layer 35.

[0084] FIG. 6 shows a schematic view of the optical core 10 including the plurality of substantially parallel spaced apart partial mirrors 30, according to an embodiment of the present disclosure.

[0085] In the illustrated embodiment of FIG. 6, the plurality of substantially parallel spaced apart partial mirrors 30 includes at least two adjacent partial mirrors 30c.

[0086] In some embodiments, a plan view in a direction substantially orthogonal to the first major surface 11 of the optical core 10, the at least two adjacent partial mirrors 30c in the plurality of partial mirrors 30, overlap each other. In some embodiments, the direction may be substantially along the z-axis of the optical core 10.

[0087] FIG. 7 shows a schematic top view of the optical core 10, according to an embodiment of the present disclosure.

[0088] In the illustrated embodiment of FIG. 7, the optical core 10 includes a continuous surface portion Ila of the first major surface 11.

[0089] In some embodiments, the partial mirrors 30 in the plurality of partial mirrors 30, in combination, span the continuous surface portion Ila of the first major surface 11.

[0090] In some embodiments, in the plan view in the direction substantially orthogonal to the first major surface 11 of the optical core 10, the partial mirrors 30 cover at least about 60% of the continuous surface portion Ila. In some embodiments, in the plan view in the direction substantially orthogonal to the first major surface 11 of the optical core 10, the partial mirrors 30 cover at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 98%, or at least about 99% of the continuous surface portion Ila.

[0091] FIG. 8A shows a graph 700 depicting an optical reflectance versus wavelength of the partial mirrors 30 (shown in FIG. 4) for first and second polarization states, according to an embodiment of the present disclosure. Specifically, FIG. 8A shows the graph 700 depicting the optical reflectance versus wavelength of the partial mirrors 30 including the optical film OF1 and for the first and second polarization states.

[0092] Optical reflectance is expressed in percent (%) in the ordinate. Wavelength is expressed in nanometers (nm) in the abscissa.

[0093] Referring to FIGS. 4 and 8A, the graph 700 includes a curve RpOOFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 0 degree and having the first polarization state and includes a curve RsOOFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 0 degree and having the second polarization state.

[0094] In some embodiments, the first polarization state substantially extends substantially along the x’-axis and the orthogonal second polarization state extends substantially along the y’-axis. Insome embodiments, the first polarization state may correspond to a p-polarization state, while the second polarization state may correspond to an s-polarization state.

[0095] The graph 700 further includes a curve Rp50OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 50 degrees and having the first polarization state and includes a curve Rs50OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 50 degrees and having the second polarization state.

[0096] Further, the graph 700 includes a curve Rp60OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 60 degrees and having the first polarization state and includes a curve Rs60OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 60 degrees and having the second polarization state.

[0097] Furthermore, the graph 700 includes a curve Rp70OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 70 degrees and having the first polarization state and includes a curve Rs70OFl depicting an optical reflectance of the optical film OF1 for the substantially collimated light 40 incident at the incident angle bl of about 70 degrees and having the second polarization state.

[0098] Table 3 provided below summarizes average optical reflectances of the optical film OF1 for the visible wavelength range, a blue wavelength range extending from about 455 nm to about 475 nm, a green wavelength range extending from about 520 nm to about 540 nm, and a red wavelength range extending from about 615 nm to about 635 nm for the different incident angles bl such as, 0 degree, 50 degrees, 60 degrees, and 70 degrees.

[0099] Table 3 also summarizes a magnitude of a ratio of a difference in the average optical reflectances for the blue and red wavelength ranges and the average optical reflectance for the blue wavelength range.Table 3

[0100] FIG. 8B shows a graph 710 depicting an optical reflectance versus wavelength of the partial mirrors 30 (shown in FIG. 4) for the first and second polarization states, according to another embodiment of the present disclosure. Specifically, FIG. 8B shows the graph 710 depicting the optical reflectance versus wavelength of the partial mirrors 30 including the optical film OF2 and for the first and second polarization states.

[0101] Optical reflectance is expressed in percent (%) in the ordinate. Wavelength is expressed in nanometers (nm) in the abscissa.

[0102] Referring to FIGS. 4 and 8B, the graph 710 includes a curve RpOOF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 0 degree and having the first polarization state and includes a curve RsOOF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 0 degree and having the second polarization state.

[0103] The graph 710 further includes a curve Rp50OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 50 degrees and having the first polarization state and includes a curve Rs50OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 50 degrees and having the second polarization state.

[0104] Further, the graph 710 includes a curve Rp60OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 60 degrees and having the first polarization state and includes a curve Rs60OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 60 degrees and having the second polarization state.

[0105] Furthermore, the graph 710 includes a curve Rp70OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 70 degrees and having the first polarization state and includes a curve Rs70OF2 depicting an optical reflectance of the optical film OF2 for the substantially collimated light 40 incident at the incident angle bl of about 70 degrees and having the second polarization state.

[0106] Table 4 provided below summarizes average optical reflectances of the optical film OF2 for the visible wavelength range, the blue wavelength range, the green wavelength range, the red wavelength range for the different first incident angles bl such as, 0 degree, 50 degrees, 60 degrees, and 70 degrees.

[0107] Table 4 also summarizes the magnitude of the ratio of the difference in the average optical reflectances for the blue and red wavelength ranges and the average optical reflectance for the blue wavelength range.Table 4

[0108] Now referring to FIGS. 4, 8 A, 8B, for the substantially collimated light 40 incident from within the optical core 10, for at least one of the mutually orthogonal first and second polarization states, and for the visible wavelength range extending from about 420 nm to about 680 nm, each of the partial mirrors 30 has an average optical reflectance of greater than about 10% and an average optical transmittance of greater than about 40% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0109] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for the at least one of the mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 15%, greater than about 20%, greater than about 25%, or greater than about 30% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0110] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0111] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 15%, greater than about 20%, greater than about 25%, or greater than about 30% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0112] For example, as is apparent from the curves Rp50OFl, Rp60OFl, Rp70OFl, Rs50OFl, Rs60OFl, Rs70OFl, for the substantially collimated light 40 incident from within the optical core 10, for each of the mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0113] Specifically, as is apparent from the curve Rp60OFl, for the substantially collimated light 40 incident from within the optical core 10, for the first polarization state, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of about 23.82% when the incident light 40 is incident at each of the second and third angles a2, a3 of about 60 degrees.

[0114] Further, as is apparent from the curve Rs60OFl, for the substantially collimated light 40 incident from within the optical core 10, for the second polarization state, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of about 18.34% when the incident light 40 is incident at each of the second and third angles a2, a3 of about 60 degrees.

[0115] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, for one of the second and third angles a2, a3, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10%.

[0116] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, for one of the second and third angles a2, a3, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 12%, greater than about 15%, greater than about 17%, greater than about 20%, or greater than about 22%.

[0117] For example, as is apparent from the curves Rp60OFl, Rs60OFl, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, for one of the second and third angles a2, a3 of about 60 degrees, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the respective average optical reflectances of about 23.85%, about 23.44%, and about 23.66% for the first polarization state and the respective average optical reflectances of about 17.72%, about 18.90%, and about 18.31% for the second polarization state.

[0118] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, for one of the second and thirdangles a2, a3, for the blue wavelength range and the red wavelength range, each of the partial mirrors 30 has respective average optical reflectances Rb60 and Rr60.

[0119] In some embodiments, a magnitude of (Rb60-Rr60) / Rb60 is less than about 10%. In some embodiments, the magnitude of (Rb60-Rr60) / Rb60 is less than about 8%, less than about 6%, less than about 4%, less than about 2%, or less than about 1%.

[0120] For example, as is apparent from the curves Rp60OFl, Rs60OFl, Rb60 is about 23.85% for the first polarization state and Rb60 is about 17.72% for the second polarization state. Further, Rr60 is about 23.66% for the first polarization state and Rr60 is about 18.31% for the second polarization state. Therefore, the magnitude of (Rb60-Rr60) / Rb60 for the optical film OF1 is about 0.8% for the first polarization state and about 3.3% for the second polarization state.

[0121] Further, as is apparent from the curves Rp60OF2, Rs60OF2, Rb60 is about 5.17% for the first polarization state and Rb60 is about 18.24% for the second polarization state. Rr60 is about 5.14% for the first polarization state and Rr60 is about 18.9% for the second polarization state. Therefore, the magnitude of (Rb60-Rr60) / Rb60 for the optical film OF2 is about 0.6% for the first polarization state and about 3.6% for the second polarization state.

[0122] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for only one of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0123] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for only one of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 15%, greater than about 20%, greater than about 25%, or greater than about 30% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0124] In some embodiments, the only one of the first and second polarization states is the s- polarization state.

[0125] For example, as is apparent from the curves Rs50OF2, Rs60OF2, Rs70OF2 for the optical film OF2, for the substantially collimated light 40 incident from within the optical core 10, for only the second polarization state, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at each of the second and third angles a2, a3.

[0126] Specifically, as is apparent from the curve Rs60OF2, for the substantially collimated light 40 incident from within the optical core 10, for only the second polarization state, and for the visiblewavelength range, each of the partial mirrors 30 has the average optical reflectance of about 18.86% when the incident light 40 is incident at each of the second and third angles a2, a3 of about 60 degrees.

[0127] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for only one of the first and second polarization states, for one of the second and third angles a2, a3, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 8%.

[0128] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for only one of the first and second polarization states, for one of the second and third angles a2, a3, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the average optical reflectance of greater than about 10%, greater than about 12%, greater than about 14%, greater than about 16%, greater than about 18%, or greater than about 20%.

[0129] In some embodiments, the only one of the first and second polarization states is the s- polarization state.

[0130] For example, as is apparent from the curve Rs60OF2, for the substantially collimated light 40 incident from within the optical core 10, for only the second polarization state, for one of the second and third angles a2, a3 of about 60 degrees, for each of the blue wavelength range, the green wavelength range, and the red wavelength range, each of the partial mirrors 30 has the respective average optical reflectance of about 18.24%, about 19.26%, and about 18.90%.

[0131] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for one of the first and second polarization states, for one of the second and third angles a2, a3, for the blue wavelength range and the red wavelength range, each of the partial mirrors 30 has respective average optical reflectances Rb60p and Rr60p of the first and second polarization states and respective average optical reflectances Rb60s and Rr60s for the other one of the first and second polarization states.

[0132] In some embodiments, a magnitude of (Rb60p-Rr60p) / Rb60p is less than a magnitude of (Rb60s-Rr60s) / Rb60s.

[0133] For example, as is apparent from the curves Rp60OFl, Rs60OFl, for the optical film OF1, Rb60p is about 23.85%, Rb60s is about 17.72%, Rr60p is about 23.66%, and Rr60s is about 18.31%. Therefore, the magnitude of (Rb60p-Rr60p) / Rb60p is about 0.8%, which is less than the magnitude of (Rb60s-Rr60s) / Rb60s of about 3.3%.

[0134] Further, as is apparent from the curves Rp60OF2, Rs60OF2, for the optical film OF2, Rb60p is about 5.17%, Rb60s is about 18.24%, Rr60p is about 5.14%, and Rr60s is about 18.9%. Therefore, the magnitude of (Rb60p-Rr60p) / Rb60p is about 0.6%, which is less than the magnitude of (Rb60s-Rr60s) / Rb60s of about 3.6%.

[0135] Further, for the substantially collimated light 40 incident from within the optical core 10, for the at least one of the mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has an average optical reflectance of less than about 20% and an average optical transmittance of greater than about 40%, when the incident light 40 is incident at the fourth angle a4.

[0136] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for the at least one of the mutually orthogonal first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of less than about 15%, less than about 10%, or less than about 5% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, greater than about 90, or greater than about 95%, when the incident light 40 is incident at the fourth angle a4.

[0137] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of less than about 20% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at the fourth angle a4.

[0138] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of less than about 15%, less than about 10%, or less than about 5% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, greater than about 90, or greater than about 95% when the incident light 40 is incident at the fourth angle a4.

[0139] In some embodiments, for an incident angle of less than about 10 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has an average optical reflectance of less than about 10%.

[0140] In some embodiments, for the incident angle of less than about 8 degrees, about 6 degrees, about 4 degrees, about 2 degrees, or about 1 degree, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of less than about 9%, less than about 8%, less than about 7%, less than about 6%, less than about 5%, or less than about 4.5%.

[0141] For example, as is apparent from the curves RpOOFl, RsOOFl, RpOOF2, RsOOF2, for the substantially collimated light 40 incident from within the optical core 10, for each of mutually orthogonal the first and second polarization states, and for the visible wavelength range, each of thepartial mirrors 30 has the average optical reflectance of less than about 20% and the average optical transmittance of greater than about 40% when the incident light 40 is incident at the fourth angle a4.

[0142] Specifically, as is apparent from the curves RpOOFl and RsOOFl, for the optical film OF1, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of about 3.45% when the incident light 40 is incident at the fourth angle a4 of about 0 degree.

[0143] Further, as is apparent from the curves RpOOF2 and RsOOF2, for the optical film OF2, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors 30 has the average optical reflectance of about 3.5% when the incident light 40 is incident at the fourth angle a4 of about 0 degree.

[0144] In some embodiments, for the substantially collimated light 40 incident from within the optical core 10, for each of the first and second polarization states, for the fourth angle a4, for the blue wavelength range and the red wavelength range, each of the partial mirrors 30 has respective average optical reflectances RbO and RrO.

[0145] In some embodiments, a magnitude of (RbO-RrO)ZRbO is less than about 35%. In some embodiments, the magnitude of (RbO-RrO)ZRbO is less than about 30%, or less than about 25%.

[0146] For example, as is apparent from the curves RpOOFl, RsOOFl, for the optical film OF1, RbO is about 3.62% for the first polarization state and RbO is about 3.61% for the second polarization state. Further, for the optical film OF1, RrO is about 2.80% for the first polarization state and RrO is about 2.80% for the second polarization state. The magnitude of (RbO-RrO)ZRbO for the optical film OF1 is about 22.6% for the first polarization state and about 22.4% for the second polarization state.

[0147] For example, as is apparent from the curves RpOOF2, RsOOF2, for the optical film OF2, RbO is about 3.84% for the first polarization state and RbO is about 3.82% for the second polarization state. Further, for the optical film OF2, RrO is about 2.90% for the first polarization state and RrO is about 3.82% for the second polarization state. The magnitude of (RbO-RrO)ZRbO for the optical film OF2 is about 24.4% for the first polarization state and about 24.1% for the second polarization state.

[0148] FIG. 9A shows a graph 800 depicting an average optical reflectance versus incident angles of the partial mirrors 30 for the first and second polarization states, according to an embodiment of the present disclosure. Specifically, FIG. 9A shows the graph 800 depicting the average optical reflectance versus incident angles of the partial mirrors 30 including the optical film OF1 and for the first and second polarization states.

[0149] Average optical reflectance is expressed in percent (%) in the ordinate. Incident angle is expressed in degrees (deg) in the abscissa.

[0150] The graph 800 includes a curve RpBOFl depicting an average optical reflectance of the optical film OF1 for the blue wavelength range and the first polarization state and includes a curveRsBOFl depicting an average optical reflectance of the optical film OF1 for the blue wavelength range and the second polarization state.

[0151] The graph 800 includes a curve RpGOFl depicting an average optical reflectance of the optical film OF1 for the green wavelength range and the first polarization state and includes a curve RsGOFl depicting an average optical reflectance of the optical film OF1 for the green wavelength range and the second polarization state.

[0152] The graph 800 includes a curve RpROFl depicting an average optical reflectance of the optical film OF1 for the red wavelength range and the first polarization state and includes a curve RsROFl depicting an average optical reflectance of the optical film OF1 for the red wavelength range and the second polarization state.

[0153] Table 5 provided below summarizes average optical reflectances and standard deviations of the optical film OF1 for the substantially collimated light 40 for different incident angle ranges, and for the blue wavelength range, the green wavelength range, and the red wavelength range.Table 5

[0154] FIG. 9B shows a graph 810 depicting an average optical reflectance versus incident angles of the partial mirrors 30 for the first and second polarization states, according to another embodiment of the present disclosure. Specifically, FIG. 9B shows the graph 810 depicting the average optical reflectance versus incident angles of the partial mirrors 30 including the optical film OF2 and for the first and second polarization states.

[0155] Average optical reflectance is expressed in percent (%) in the ordinate. Incident angle is expressed in degrees (deg) in the abscissa.

[0156] The graph 810 includes a curve RpBOF2 depicting an average optical reflectance of the optical film OF2 for the blue wavelength range and the first polarization state and includes a curve RsBOF2 depicting an average optical reflectance of the optical film OF2 for the blue wavelength range and the second polarization state.

[0157] The graph 810 includes a curve RpGOF2 depicting an average optical reflectance of the optical film OF2 for the green wavelength range and the first polarization state and includes a curve RsGOF2 depicting an average optical reflectance of the optical film OF2 for the green wavelength range and the second polarization state.

[0158] The graph 810 includes a curve RpROF2 depicting an average optical reflectance of the optical film OF2 for the red wavelength range and the first polarization state and includes a curve RsROF2 depicting an average optical reflectance of the optical film OF2 for the red wavelength range and the second polarization state.

[0159] Table 6 provided below summarizes average optical reflectances and standard deviations of the optical film OF2 for the substantially collimated light 40 for the different incident angle ranges, and for the blue wavelength range, the green wavelength range, and the red wavelength range.Table 6

[0160] Referring to FIGS. 4, 9A, 9B, in some embodiments, when the partial mirror 30 is disposed in the medium having the index of refraction of greater than about 1.3 and the substantially collimated light 40 is incident on the partial mirror 30 from within the medium, then for each first incident angle (e.g., the incident angle bl) of less than at least about 20 degrees, for at least one of the mutually orthogonal first and second polarization states, and for each of the blue wavelength range, the green wavelength range, and the red wavelength range, the partial mirror 30 has a first average optical reflectance.

[0161] In some embodiments, the first incident angle is less than at least about 25 degrees, less than at least about 30 degrees, or less than at least about 35 degrees. In some embodiments, the first incident angle is about 35 degrees.

[0162] The first average optical reflectances for all the first incident angles of less than at least about 20 degrees, the at least one of the first and second polarization states, and the blue, green, and red wavelength ranges have a combined average Ravg and a combined standard deviation Rst.

[0163] The combined average Ravg is less than or equal to about 10%, i.e., Ravg < 10%. In some embodiments, Ravg < 9%, Ravg < 8%, Ravg < 7%, Ravg < 6%, Ravg < 5%, or Ravg < 4.5%. In some embodiments, Ravg < 10% for each of the first and second polarization states.

[0164] For example, for the optical film OF1, Ravg is about 4.07% for the first polarization state and Ravg is about 4.22% for the second polarization state. Further, for the optical film OF2, Ravg is about 3.34% for the first polarization state and Ravg is about 4.19% for the second polarization state.

[0165] Further, a ratio between the combined standard deviation Rst and the combined average Ravg is less than or equal to about 0.25, i.e., Rst / Ravg < 0.25. In some embodiments, Rstd / Ravg isless than about 0.22, less than about 0.20, less than about 0.18, less than about 0.17, less than about 0.16, or less than about 0.1%.

[0166] For example, for the optical film OF1, Rst / Ravg is about 0.14 for the first polarization state and about 0.15 for the second polarization state. Furthermore, for the optical film OF2, Rst / Ravg is about 0.15 for the first polarization state and about 0.15 for the second polarization state.

[0167] Table 7 provided below summarizes the combined average Ravg, the combined standard deviation Rst, and the ratio Rst / Ravg of the optical film OF1 for both the first and second polarization states, for the first polarization state, and the second polarization state in the visible wavelength range (i.e., including the blue wavelength range, the green wavelength range, the red wavelength range) for the different incident angle ranges.Table 7

[0168] Table 8 provided below summarizes the combined average Ravg, the combined standard deviation Rst, and the ratio Rst / Ravg of the optical film OF2 for both the first and second polarization states, for the first polarization state, and the second polarization state in the visible wavelength range for the different incident angle ranges.Table 8

[0169] Referring to FIGS. 4, 8A-8B, and 9A-9B, for at least one second incident angle of greater than about 40 degrees (e.g., the incident angle bl of about 60 degrees) and for the visible wavelength range, the partial mirror 30 has an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40%.

[0170] In some embodiments, for the at least one second incident angle of greater than about 40 degrees and for the visible wavelength range, the partial mirror 30 has the average optical reflectance of greater than about 15%, greater than about 20%, greater than about 25%, or greater than about 30% and the average optical transmittance of greater than about 45%, greater than about 50%, greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80%.

[0171] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, the partial mirror 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% for each of the first and second polarization states.

[0172] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 10%. In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 12.5%, greater than about 15%, greater than about 17.5%, or greater than about 20%.

[0173] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, the partial mirror 30 has the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% for only one of the first and second polarization states. In some embodiments, the only one of the first and second polarization states is the s-polarization state.

[0174] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for only one of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 10%. In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for only one of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 12.5%, greater than about 15%, greater than about 17.5%, or greater than about 20%.

[0175] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of less than about 50%. In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of less than about 45%, less than about 40%, less than about 35%, less than about 30%, or less than about 25%.

[0176] In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has an average optical absorption of less than about 5%. In some embodiments, for the at least one second incident angle of greater than about 40 degrees, for each of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical absorption of less than about 4%, less than about 3%, less than about 2%, or less than about 1%.

[0177] In some embodiments, for a third incident angle that is greater than the at least one second incident angle by no more than 15 degrees, for at least one of the first and second polarization states, and for the blue and red wavelength ranges, the partial mirror 30 has respective average optical reflectances Rb70 and Rr70. In some embodiments, the third incident angle is about 70 degrees.

[0178] In some embodiments, a magnitude of (Rb70-Rr70) / Rb70 is greater than about 10%. In some embodiments, the magnitude of (Rb70-Rr70) / Rb70 is greater than about 15%, or greater than about 20%.

[0179] For example, as is apparent from the curves Rp70OFl, Rs70OFl, Rb70 is about 61.16% for the first polarization state and Rb70 is about 31.32% for the second polarization state. Further, Rr70 is about 5.88% for the first polarization state and Rr70 is about 38.87% for the second polarization state. Therefore, the magnitude of (Rb70-Rr70) / Rb70 for the optical film OF1 is about 90.4% for the first polarization state and about 17.7% for the second polarization state.

[0180] Further, as is apparent from the curves Rp70OF2, Rs70OF2, Rb70 is about 13.38% for the first polarization state and Rb70 is about 32.02% for the second polarization state. Rr70 is about 3.28% for the first polarization state and Rr70 is about 38.15% for the second polarization state. Therefore, the magnitude of (Rb70-Rr70) / Rb70 for the optical film OF2 is about 75.5% for the first polarization state and about 19.2% for the second polarization state.

[0181] In some embodiments, the magnitude of (Rb70-Rr70) / Rb70 for one of the first and second polarization states is greater than the magnitude of (Rb70-Rr70) / Rb70 for the other one of the first and second polarization states by at least a factor of 1.5. In some embodiments, the magnitude of (Rb70-Rr70) / Rb70 for one of the first and second polarization states is greater than the magnitude of (Rb70-Rr70) / Rb70 for the other one of the first and second polarization states by at least a factor of 2, 2.5, 3, 3.5, 4, 4.5, or 5.

[0182] For example, in the above examples of the optical films OF1 and OF2, the magnitude of (Rb70-Rr70) / Rb70 for the first polarization state is greater than the magnitude of (Rb70-Rr70) / Rb70 for the second polarization state. Specifically, for the optical film OF1, the magnitude of (Rb70- Rr70) / Rb70 for the first polarization state is greater than the magnitude of (Rb70-Rr70) / Rb70 for the second polarization state by a factor of 5.1 and for the optical film OF2, the magnitude of (Rb70- Rr70) / Rb70 for the first polarization state is greater than the magnitude of (Rb70-Rr70) / Rb70 for the second polarization state by a factor of 3.9.

[0183] In some embodiments, for the third incident angle that is greater than the at least one second incident angle by at least about 5 degrees, for only one of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has an average optical reflectance of greater than about 20%. In some embodiments, for the third incident angle that is greater than the at least one second incident angle by at least about 5 degrees, for only one of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 25%, or greater than about 30%.

[0184] For example, for the optical film OF1, for the third incident angle of about 70 degrees that is greater than the at least one second incident angle of about 60 degrees by about 10 degrees, for the second polarization state, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of about 31.32%, about 33.51%, and about 36.87%, respectively.

[0185] Further, for the optical film OF2, for the third incident angle of about 70 degrees that is greater than the at least one second incident angle of about 60 degrees by about 10 degrees, for the second polarization state, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of about 32.02%, about 35.14%, and about 38.15%, respectively.

[0186] In some embodiments, for the third incident angle that is greater than the at least one second incident angle by at least about 5 degrees, for only one of the first and second polarization states, and for at least one of the blue, the green, and the red wavelength ranges, the partial mirror 30 has an average optical reflectance of greater than about 35%. In some embodiments, for the third incident angle that is greater than the at least one second incident angle by at least about 5 degrees, for only one of the first and second polarization states, and for each of the blue, the green, and the red wavelength ranges, the partial mirror 30 has the average optical reflectance of greater than about 40%, greater than about 45%, greater than about 50%, greater than about 55%, or greater than about 60%.

[0187] For example, for the optical film OF1, for the third incident angle of about 70 degrees that is greater than the at least one second incident angle of about 60 degrees by about 10 degrees, for the first polarization state, and for the blue and the green wavelength ranges, the partial mirror 30 has the average optical reflectance of about 61.16% and about 63.74%, respectively.

[0188] FIG. 10 shows a graph 1000 depicting an optical reflectance versus wavelength of the partial mirrors 30 for a substantially collimated unpolarized light, according to an embodiment of the present disclosure.

[0189] Optical reflectance is expressed in percent (%) in the ordinate. Wavelength is expressed in nanometers (nm) in the abscissa.

[0190] The graph 1000 includes a curve OFlunpO depicting an optical reflectance of the optical film OF1 for the substantially collimated unpolarized light incident at about 0 degree and a curveOF2unpO depicting an optical reflectance of the optical film OF2 for the substantially collimated unpolarized light incident at about 0 degree.

[0191] The graph 1000 further includes a curve OFlunp50 depicting an optical reflectance of the optical film OF1 for the substantially collimated unpolarized light incident at about 50 degrees and a curve OF2unp50 depicting an optical reflectance of the optical film OF2 for the substantially collimated unpolarized light incident at about 50 degrees.

[0192] The graph 1000 further includes a curve OFlunp60 depicting an optical reflectance of the optical film OF1 for the substantially collimated unpolarized light incident at about 60 degrees and a curve OF2unp60 depicting an optical reflectance of the optical film OF2 for the substantially collimated unpolarized light incident at about 60 degrees.

[0193] The graph 1000 further includes a curve OFlunp70 depicting an optical reflectance of the optical film OF1 for the substantially collimated unpolarized light incident at about 70 degrees and a curve OF2unp70 depicting an optical reflectance of the optical film OF2 for the substantially collimated unpolarized light incident at about 70 degrees.

[0194] Table 9 provided below summarizes average optical reflectances and standard deviations of the optical film OF1 for the substantially collimated unpolarized light incident at different incident angles, and for the blue wavelength range, the green wavelength range, and the red wavelength range.Table 9

[0195] Table 10 provided below summarizes average optical reflectances and standard deviations of the optical film OF2 for the substantially collimated unpolarized light incident at the different incident angles, and for the blue wavelength range, the green wavelength range, and the red wavelength range.Table 10

[0196] Referring to FIGS. 1, 4, and 10, when the partial mirror 30 is disposed in the medium having the index of refraction of greater than about 1.3, and the substantially collimated unpolarized light is incident on the partial mirror 30 from within the medium, then for the visible wavelength range and for sequentially increasing first through fourth incident angles, where the first incident angle is less than about 10 degrees (e.g., about 0 degree), and where the second through fourth incident angles are greater than the first incident angle by at least 30 degrees (e.g., about 50 degrees), are less than about 80 degrees (e.g., about 70 degrees), and are spaced apart by at least 5 degrees (e.g., about 10 degrees), the partial mirror 30 has respective average optical reflectances Ravgl through Ravg4 (i.e., the average optical reflectances Ravgl, Ravg2, Ravg3, Ravg4) and respective standard deviations Rstdl through Rstd4 (i.e., the standard deviations Rstdl, Rstd2, Rstd3, Rstd4).

[0197] In some embodiments, the first incident angle is less than about 8 degrees, less than about 6 degrees, less than about 4 degrees, less than about 2 degrees, or less than about 1 degree.

[0198] In some embodiments, the second through fourth incident angles are greater than the first incident angle by at least 35 degrees, at least 40 degrees, at least 45 degrees, or at least 50 degrees. In some embodiments, the second through fourth incident angles are less than about 75 degrees. In some embodiments, the second through fourth incident angles are spaced apart by at least 10 degrees.

[0199] The average optical reflectance Ravgl is less than about 10%. In some embodiments, the average optical reflectance Ravgl is less than about 9%, less than about 8%, less than about 7%, less than about 6%, less than about 5%, less than about 4%, or less than about 3%. For example, the average optical reflectance Ravgl is about 3.45%.

[0200] The average optical reflectance Ravg3 is greater than about 10% and less than about 35%. In some embodiments, the average optical reflectance Ravg3 is greater than about 15%, or greater than about 20% and less than about 30%, or less than about 25%. For example, the average optical reflectance Ravg3 is about 21.08%.

[0201] Further, each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than each of Rstd2 / Ravg2 and Rstd3 / Ravg3 by at least a factor of 2. In some embodiments, each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than each of Rstd2 / Ravg2 and Rstd3 / Ravg3 by at least a factor of 4, 6, 8, 10, 12, or 15. For example, Rstdl / Ravgl is about 20.28, Rstd4 / Ravg4 is about 36.18, Rstd2 / Ravg2 is about 3.18, and Rstd3 / Ravg3 is about 3.04.

[0202] In some embodiments, Ravg2 is greater than Ravgl by at least 2. In some embodiments, Ravg2 is greater than Ravgl by at least 3%, at least 4%, at least 5%, at least 6%, or at least 7%. For example, Ravg2 is about 10.68% and Ravg2 is greater than Ravgl by about 7.23%.

[0203] In some embodiments, Ravg2 is less than Ravg3 by at least 5%. In some embodiments, Ravg2 is less than Ravg3 by at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. For example, Ravg2 is less than Ravg3 by about 10.4%.

[0204] In some embodiments, Ravg4 is greater than Ravg3 by at least 5%. In some embodiments, Ravg4 is greater than Ravg3 by at least 7%, at least 10%, at least 12%, or at least 15%. For example, Ravg4 is about 35.28% and Ravg4 is greater than Ravg3 by about 14.5%.

[0205] In some embodiments, each of Rstd2 / Ravg2 and Rstd3 / Ravg3 is less than about 10%. In some embodiments, each of Rstd2 / Ravg2 and Rstd3 / Ravg3 is less than about 7%, less than about 5%, less than about 4%, or less than about 3%. For example, Rstd2 / Ravg2 is about 3.18 and Rstd3 / Ravg3 is about 3.04.

[0206] In some embodiments, each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 12%. In some embodiments, each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 15%, greater than about 17%, or greater than about 20%. In some embodiments, each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 20% .

[0207] In some embodiments, at least one of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 20%. In some embodiments, at least one of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 25%, greater than about 30%, or greater than about 35%. For example, Rstdl / Ravgl is about 20.28 and Rstd4 / Ravg4 is about 36.18.

[0208] In some embodiments, each of Rstdl, Rstd2, and Rstd3 is less than about 5%. In some embodiments, each of Rstdl, Rstd2, and Rstd3 is less than about 4%, less than about 3%, less than about 2%, or less than about 1%. For example, Rstdl is about 0.70%, Rstd2 is about 0.34%, and Rstd3 is about 0.64%.

[0209] In some embodiments, Rstd4 is greater than about 5%. In some embodiments, Rstd4 is greater than about 7%, greater than about 10%, greater than about 12%, or greater than about 15%. For example, Rstd4 is about 12.76%.

[0210] Referring to FIGS. 1 to 10, for the substantially collimated light 40 incident from within the optical core 10, for at least one of mutually orthogonal first and second polarization states, and for the visible wavelength range, the partial mirrors 30 may therefore achieve the average optical reflectance of greater than about 10% and the average optical transmittance of greater than about 40% when the incident light 40 is incident on the first plurality of light extracting partial mirrors 30a and the average optical reflectance of less than about 20% and the average optical transmittance of greater than about 40% when the incident light 40 is incident on the second plurality of light transmitting partial mirrors 30b. In other words, the optical waveguide construction 300 may maximize an optical transmission or minimize an optical reflection at lower angles (i.e., the fourth angle a4) and may maximize an optical transmission at higher angles (i.e., the second angle and third angles a2, a3).

[0211] Further, maximizing the optical transmission or minimizing the optical reflection at the lower angles (i.e., the fourth angle) may further prevent trapping of the image light 20, which may otherwise reduce an efficiency of the optical waveguide construction 300.

[0212] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0213] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

CLAIMS1. An optical waveguide construction comprising: an optical core configured to propagate an image light along an in-plane first direction primarily by total internal reflection such that an incident first angle of the propagating image light on a first major surface of the optical core is greater than a critical angle; a plurality of substantially parallel spaced apart partial mirrors embedded in the optical core, the partial mirrors arranged along the first direction and extending along substantially a same in-plane orthogonal second direction, each of the partial mirrors making an oblique second angle with the first major surface, the image light incident on each of a first plurality of light extracting partial mirrors in the plurality of partial mirrors at an incident third angle and the image light incident on each of a second plurality of light transmitting partial mirrors in the plurality of partial mirrors at an incident fourth angle less than the third angle by at least 15 degrees, each of the light extracting partial mirrors extracting at least a portion of the propagating image light that is incident on the light extracting partial mirror toward a viewer, the viewer configured to view an object in a real-world scene through the partial mirrors, such that for a substantially collimated light incident from within the optical core, for at least one of mutually orthogonal first and second polarization states, and for a visible wavelength range extending from about 420 nm to about 680 nm, each of the partial mirrors has: an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40% when the incident light is incident at each of the second and third angles; and an average optical reflectance of less than about 20% and an average optical transmittance of greater than about 40% when the incident light is incident at the fourth angle.

2. The optical waveguide construction of claim 1, wherein each of the second and the third angles is greater than about 30 degrees, wherein the second and the third angles are within about 15 degrees of each other, and wherein the fourth angle is less than about 15 degrees.

3. The optical waveguide construction of claim 1, wherein the partial mirrors in the plurality of partial mirrors, in combination, span a continuous surface portion of the first major surface, and wherein in a plan view in a direction substantially orthogonal to the first major surface of the optical core, the partial mirrors cover at least about 60% of the continuous surface portion.

4. The optical waveguide construction of claim 1, wherein in a plan view in a direction substantially orthogonal to the first major surface of the optical core, at least two adjacent partial mirrors in the plurality of partial mirrors, overlap each other.

5. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, for each of the first and second polarization states, and for the visible wavelength range, each of the partial mirrors has: an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40% when the incident light is incident at each of the second and third angles; and an average optical reflectance of less than about 20% and an average optical transmittance of greater than about 40% when the incident light is incident at the fourth angle.

6. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, and for the visible wavelength range, each of the partial mirrors has: for only one of the first and second polarization states, an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40% when the incident light is incident at each of the second and third angles; and for each of the first and second polarization states, an average optical reflectance of less than about 20% and an average optical transmittance of greater than about 40% when the incident light is incident at the fourth angle.

7. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, for each of the first and second polarization states, for the fourth angle, for a blue wavelength range extending from about 455 nm to about 475 nm, and a red wavelength range extending from about 615 nm to about 635 nm, each of the partial mirrors has respective average optical reflectances RbO and RrO, and wherein a magnitude of (Rb0-Rr0) / Rb0 is less than about 35%.

8. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, for each of the first and second polarization states, for one of the second and third angles, for a blue wavelength range extending from about 455 nm to about 475 nm, and a red wavelength range extending from about 615 nm to about 635 nm, each of the partial mirrors has respective average optical reflectances Rb60 and Rr60, and wherein a magnitude of (Rb60-Rr60) / Rb60 is less than about 10%.

9. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, for one of the second and third angles, for a blue wavelength range extending from about 455 nm to about 475 nm, and a red wavelength range extending from about 615 nm to about 635 nm, each of the partial mirrors has respective optical reflectances Rb60p and Rr60p for one of the first and second polarization states, and respective average optical reflectances Rb60s and Rr60s for the other one of the first and second polarization states, and wherein a magnitude of (Rb60p- Rr60p) / Rb60p is less than a magnitude of (Rb60s-Rr60s) / Rb60s.

10. The optical waveguide construction of claim 1, wherein for the substantially collimated light incident from within the optical core, for only one of the first and second polarization states, for one of the second and third angles, for each of a blue wavelength range extending from about 455 nm to about 475 nm, for a green wavelength range extending from about 520 nm to about 540 nm, and a red wavelength range extending from about 615 nm to about 635 nm, each of the partial mirrors has an average optical reflectance of greater than about 8%.

11. An optical system comprising: the optical waveguide construction of claim 1; and a display configured to form and emit an image, image lights from the emitted image entering the optical core and comprising the image light propagating along the in-plane first direction primarily by total internal reflection.

12. A partial mirror comprising a plurality of polymeric layers numbering between about 100 and 400 in total, each of the polymeric layers having an average thickness of less of than about 500 nm, a maximum difference between indices of refraction of the polymeric layers along each of mutually orthogonal in-plane first and second directions and a normal direction orthogonal to the first and second directions being less than about 0.05, such that when the partial mirror is disposed in a medium having an index of refraction of greater than about 1.3 and a substantially collimated light is incident on the partial mirror from within the medium, then for each first incident angle of less than at least about 20 degrees, for at least one of mutually orthogonal first and second polarization states, and for each of a blue wavelength range extending from about 455 nm to about 475 nm, a green wavelength range extending from about 520 nm to about 540 nm, and a red wavelength range extending from about 615 nm to about 635 nm, the partial mirror has a first average optical reflectance, wherein the first average optical reflectances for all the first incident angles, the at least one of the first and second polarization states, and the blue, green, and red wavelength ranges have a combined average Ravg and a combined standard deviation Rst, Ravg < 10%, Rst / Ravg < 0.25, and for at least one second incident angle of greater than about 40 degrees and for a visible wavelength range extending from about 420 nm to about 680 nm, the partial mirror has an average optical reflectance of greater than about 10%, and an average optical transmittance of greater than about 40%.

13. An optical waveguide construction comprising: an optical core configured to propagate an image light along an in-plane first direction primarily by total internal reflection such that an incident first angle of the propagating image light on a first major surface of the optical core is greater than a critical angle; anda plurality of partial mirrors of claim 12, embedded and spaced apart in the optical core, the partial mirrors arranged along the first direction and extending along substantially a same in-plane orthogonal second direction.

14. A partial mirror comprising a plurality of polymeric layers numbering between about 100 and 400 in total, each of the polymeric layers having an average thickness of less of than about 500 nm, a maximum difference between indices of refraction of the polymeric layers along each of mutually orthogonal in-plane first and second directions and a normal direction orthogonal to the first and second directions being less than about 0.05, such that when the partial mirror is disposed in a medium having an index of refraction of greater than about 1.3 and a substantially collimated unpolarized light is incident on the partial mirror from within the medium, then for a visible wavelength range extending from about 420 nm to about 680 nm, and for sequentially increasing first through fourth incident angles, where the first incident angle is less than about 10 degrees, and where the second through fourth incident angles are greater than the first incident angle by at least 30 degrees, are less than about 80 degrees, and are spaced apart by at least 5 degrees, the partial mirror has respective average optical reflectances Ravgl through Ravg4 and respective standard deviations Rstdl through Rstd4, wherein:Ravi is less than about 10%;Rav3 is greater than about 10% and less than about 35%; and each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than each of Rstd2 / Ravg2 and Rstd3 / Ravg3 by at least a factor of 2.

15. The partial mirror of claim 14, wherein Ravg2 is greater than Ravgl by at least 2% and less than Ravg3 by at least 5%, wherein Ravg4 is greater than Ravg3 by at least 5%, wherein each of Rstd2 / Ravg2 and Rstd3 / Ravg3 is less than about 10%, wherein each of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 12%, wherein at least one of Rstdl / Ravgl and Rstd4 / Ravg4 is greater than about 20%, wherein each of Rstdl, Rstd2, and Rstd3 is less than about 5%, and wherein Rstd4 is greater than about 5%.

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