Multilayer optical film

Abstract

An optical film includes a plurality of optical repeat units (ORUs). The ORUs include opposite first and second terminal ORUs that are furthest from each other among the ORUs. For first and second intermediate ORUs of the plurality of ORUs, the first and second intermediate ORUs are spaced apart from each of the first and second terminal ORUs by at least 10 other ORUs of the plurality of ORUs, the first and second intermediate ORUs are spaced apart from each other by no more than about 5 other ORUs of the plurality of ORUs, and have respective average physical thicknesses H1 and H2, a magnitude of (H1-H2) / ((H1+H2) / 2) is greater than about 1%. For normally incident light, the plurality of ORUs has an average optical transmission that averages over a visible wavelength range of at least 60%, and an average optical density that averages over a first infrared wavelength range continuously extending from about 800 nm to about 1100 nm of greater than about 3.

Description

Technical Field

[0001] This disclosure relates generally to optical films, and more particularly to high-density broadband reflector films. Background Technology

[0002] Multilayer optical films (MOFs) are used in numerous applications, including consumer electronics and automotive. Polymer MOFs are formed by co-extruding tens to hundreds of layers of molten polymer and subsequently orienting or stretching the resulting film. These microlayers have different refractive index properties and are thin enough that light is reflected at the interfaces between adjacent microlayers. Broadband visible reflectors reflect all or virtually all of the visible spectrum and can be used in display and lighting applications. Summary of the Invention

[0003] Some aspects of this disclosure relate to an optical film comprising a plurality of optical repeating units (ORUs) co-extruded and co-stretched together, with a total number of at least 15. Each ORU has an average physical thickness of less than about 1000 nm and comprises at least two distinct polymer layers. The ORU includes a first and a second terminal ORU, which are the furthest apart from each other among the ORUs. For a first and a second intermediate ORU among the plurality of ORUs, the first and second intermediate ORUs are spaced apart from each of the first and second terminal ORUs by at least 10 other ORUs among the plurality of ORUs, the first and second intermediate ORUs being spaced apart from each other by no more than about 5 other ORUs among the plurality of ORUs, and having corresponding average physical thicknesses H1 and H2, where the value of (H1-H2) / ((H1+H2) / 2) is greater than about 1%. For substantially collimated, substantially perpendicular incident light, the plurality of ORUs have an average optical transmittance of at least 60%, which is averaged over a visible wavelength range continuously extending from about 420 nm to about 680 nm, and averaged over mutually orthogonal first and second polarization states. For substantially collimated, substantially perpendicular incident light, the plurality of ORUs have an average optical density greater than about 3, which is averaged over a first infrared wavelength range continuously extending from about 800 nm to about 1100 nm, and averaged over first and second polarization states.

[0004] Some other aspects of this disclosure relate to an optical film comprising a plurality of optical repeating units (ORUs) co-extruded and co-stretched together, with a total number of at least 15. Each ORU has an average physical thickness of less than about 1000 nm and comprises at least two distinct polymer layers. For substantially collimated incident light, and as the incident angle increases from a first incident angle of less than about 10 degrees to a second incident angle of greater than about 35 degrees, the average light transmittance of the plurality of ORUs remains greater than about 50%, averaged over a visible wavelength range continuously extending from about 420 nm to about 680 nm, and averaged over mutually orthogonal first and second polarization states. The average optical density of the plurality of ORUs remains greater than about 5, averaged over a first infrared wavelength range continuously extending from about 800 nm to about 1100 nm, and averaged over the first and second polarization states.

[0005] Some other aspects of this disclosure relate to an optical film comprising a plurality of optical repeating units (ORUs) co-extruded and co-stretched together, with a total number of at least 15. Each ORU has an average physical thickness of less than about 1000 nm and comprises at least two distinct polymer layers. For substantially collimated incident light, the wavelength-variable average optical density of the optical film across mutually orthogonal first and second polarizations includes a high optical density region at least 200 nm wide, having an average optical density greater than about 3, averaged over the high optical density region and across the first and second polarization states, and situated within a wavelength region of interest extending continuously between about 600 nm and about 1400 nm. The high optical density region is defined by a left band edge and an opposing right band edge, with the optical density along the left band edge generally increasing with increasing wavelength, and the optical density along the right band edge generally decreasing with increasing wavelength. At least across a wavelength range where the optical density increases from about 1 to about 3.5, the first best linear fit to the left band edge has a slope that is greater than about 0.06 / nm for a first incident angle less than about 10 degrees, and that the slope increases as the incident angle increases to a second incident angle greater than about 35 degrees.

[0006] Some aspects of this disclosure relate to a system comprising a housing defining an opening for allowing visible light to pass through. An optical film of one or more aspects of this disclosure is disposed on and covers the opening. For a light source emitting a first light having wavelengths in a visible wavelength range continuously extending from about 420 nm to about 680 nm and a second light having wavelengths in a high optical density region, and for all incident angles between a first and a second incident angle, the optical film transmits at least 60% of the first light and reflects at least 99% of the second light. Attached Figure Description

[0007] Various aspects of this disclosure will be discussed in more detail with reference to the accompanying drawings, in which,

[0008] Figure 1 A multilayer optical film having multiple optical repeating units (ORUs) is schematically shown according to some embodiments of the present disclosure;

[0009] Figure 2A and Figure 2B The thickness of different optical films varies with the number of layers in the ORU, as shown graphically.

[0010] Figure 3A and Figure 3B The thickness ratio between two ORUs in the optical film is shown graphically, based on some aspects.

[0011] Figure 4A and Figure 4B The transmission spectra of different optical films as a function of the number of ORUs are shown graphically.

[0012] Figure 4C and Figure 4D The transmission spectra of different optical films at different wavelengths are shown graphically.

[0013] Figure 5A and Figure 5B The optical density along the left and right band edges of different optical films as a function of wavelength is shown graphically.

[0014] Figure 6A A system having an optical film according to one or more aspects of this disclosure is schematically illustrated.

[0015] Figure 7 The light transmittance of different optical films under mutually orthogonal polarizations and at different incident angles is illustrated graphically.

[0016] Figure 8A The refractive indices of the two different polymer layers of ORU are graphically represented, and

[0017] Figure 8B The difference in refractive index between the two different polymer layers of ORU is represented graphically.

[0018] The figures are not necessarily drawn to scale. Similar numbers used in the figures refer to similar parts. However, it should be understood that using numbers to refer to parts in a given figure is not intended to restrict parts to be labeled with the same numbers in another figure. Detailed Implementation

[0019] Reference is made in the following description to the accompanying drawings, which form part of this disclosure and in which various embodiments are illustrated by way of example. It should be understood that other embodiments are conceivable and may be practiced without departing from the scope or spirit of this description. Therefore, the following detailed description should not be considered as limiting.

[0020] The terms "transmittance" and "transmission" refer to the ratio of the total transmittance of a material layer to the total transmittance received by the material, which can account for the effects of absorption, scattering, reflection, etc. Transmittance (T) can be expressed in the range of 0 to 1 or as a percentage (T%).

[0021] The term "optical density" refers to a material's ability to allow light to pass through it. The higher the optical density, the lower the transmittance. Optical density can be expressed as the negative logarithm of [transmittance / 100%] to base 10 and is a dimensionless quantity.

[0022] The term "optical repeating unit" refers to a stack of at least two individual layers that are repeated over the thickness of a multilayer optical film, but unless otherwise mentioned in this disclosure, all repeating layers do not need to have the same thickness.

[0023] Embodiments of this disclosure describe a multilayer optical film (MOF) that provides very high reflectivity and very low absorptivity at near-infrared wavelengths from about 800 nm to about 1100 nm across angles from 0 to 55 degrees, and has a relatively high level of visible light transmission. The optical film according to one or more embodiments provides sharp band edges to minimize the amount of visible light reflected at all angles.

[0024] In some aspects, the multilayer optical film design according to this disclosure includes multiple polymeric optical layers (such as alternating PEN and PMMA layers) designed to provide a thickness gradient of high reflectivity from 780 nm to 1100 nm across an angle of 0 to 55 degrees. The film is designed to provide high visible light transmittance, high RF transmittance, and low absorptivity in a wavelength range of 400 nm to 1400 nm. The film is also designed to have sharp band edges and high reflectivity in the target reflective region. In some aspects, the film has an outer surface layer comprising a polycarbonate alloy on both outer surfaces.

[0025] like Figure 1As illustrated, according to some aspects, the optical film (200) comprises a plurality of optical repeating units (10) (ORUs), which are also referred to as multilayer stacks. The optical film may comprise a total of at least 15, or 20, or 50, or 75, or 100, or 150, or 175, or 200, or 250, or 300 ORUs. In some aspects, the optical film may comprise about 650 ORUs. Each ORU may comprise at least two different polymer layers (11, 12) that are co-extruded and co-stretched. For example, each ORU, as described in, for instance, can be prepared by co-extruding alternating polymer layers with different refractive indices (11, 12): U.S. Patent No. 5,882,774 (Jonza et al.); U.S. Patent No. 6,045,894 (Jonza et al.); U.S. Patent No. 6,368,699 (Gilbert et al.); U.S. Patent No. 6,531,230 (Weber et al.); U.S. Patent No. 6,667,095 (Wheatley et al.); U.S. Patent No. 6,783,349 (Neavin et al.); U.S. Patent No. 7,271,951 U.S. Patent No. B2 (Weber et al.); U.S. Patent No. 7,632,568 (Padiyath et al.); U.S. Patent No. 7,652,736 (Padiyath et al.); and U.S. Patent No. 7,952,805 (McGurran et al.); and PCT Publication No. WO95 / 17303 (Ouderkirk et al.) and PCT Publication No. WO99 / 39224 (Ouderkirk et al.).

[0026] In some cases, one of the two distinct polymer layers (11, 12) comprises polyethylene naphthalate (PEN), and the other of the two distinct polymer layers comprises polymethyl methacrylate (PMMA). For at least one visible wavelength in the visible wavelength range, the refractive index of one of the two distinct polymer layers may be greater than about 1.6, or 1.65, or 1.7. For at least one visible wavelength, the refractive index of the other of the two distinct polymer layers may be less than about 1.6, or 1.55, or 1.5 (see [link to relevant documentation]). Figure 8A The magnitude of the maximum difference between the refractive indices of the two different polymer layers (11, 12) in the first infrared wavelength range, and the magnitude of the average value taken over the first and second polarization states, may be greater than about 0.05 and about 0.4, or about 0.1 and about 0.3, or about 0.15 and about 0.25 (see...). Figure 8B ).

[0027] An ORU comprises the first and second most distant relative ORUs (10a and 10b) among the ORUs. Each ORU has an average physical thickness of less than approximately 1000 nm, or 900 nm, or 800 nm, or 700 nm, or 600 nm, or 500 nm, or 400 nm, or 300 nm, or 200 nm, or 175 nm, or 150 nm, or 140 nm, or less than 130 nm. Figure 2A Different optical films (OF1, OF2, OF3) with approximately 650 ORUs (including the first terminal ORU (10a) and the second terminal ORU (10b)) are shown. Figure 2A As shown, the ORU thickness of different optical films (OF1, OF2, OF3) can be less than about 215 nm. The ORU (10) also includes a first intermediate ORU (10c) and a second intermediate ORU (10d), which are spaced apart from each of the first terminal ORU (10a) and the second terminal ORU (10b) by at least 10, 15, 20, 50, 75, 100, 150, 90, or 100 other ORUs. In some aspects, the first intermediate ORU (10c) and the second intermediate ORU (10d) are spaced apart from each other by no more than about 5, 4, 3, 2, 1, or 0 other ORUs. Figure 2B In the illustrated example, the first intermediate ORU (10c) and the second intermediate ORU (10d) are spaced apart from each other by approximately one other ORU. The first intermediate ORU (10c) has an average physical thickness H1, and the second intermediate ORU (10d) has an average physical thickness H2. In some optical films, the value of (H1-H2) / ((H1+H2) / 2) is greater than approximately 1%, or 1.5%, or 2%, or 2.5%, or 3%, and in some other optical films, the value of (H1-H2) / ((H1+H2) / 2) may be greater than approximately 4%, or 5%, or 6%, or 8%, or 10%, or 15%, such as... Figure 3A and Figure 3B exemplified.

[0028] Table 1 shows the values ​​of (H1-H2) / ((H1+H2) / 2) for different optical films OF1, OF2 and OF3 according to some embodiments of this disclosure.

[0029]

[0030] In some cases, the physical thickness H2 of the second intermediate ORU (10d) can be greater than the physical thickness H1 of the first intermediate ORU (10c).

[0031] In some cases, multiple optical repeating units may be disposed between a first surface layer (13a) and a second surface layer (13b), and co-extruded and co-stretched with the first and second surface layers. Each of the two surface layers may have an average thickness greater than about 500 nm, or 750 nm, or 1000 nm, or 1500 nm, or 2000 nm. These optional surface layers (13a, 13b) may protect the ORU from damage, facilitate co-extrusion processing, and / or enhance post-processing mechanical properties. The surface layers (13a, 13b) are typically thicker than the ORU (10). The thickness of the surface layers (13a, 13b) is typically at least two times, or at least four times, or at least ten times the thickness of the individual ORUs. An auxiliary layer (13c) may be disposed between two of the multiple ORUs and may be co-extruded and co-stretched with the multiple ORUs. An auxiliary layer (13c) may be disposed between the opposing first and second terminal ORUs (10a and 10b) and may have an average thickness greater than approximately 250 nm, or 300 nm, or 350 nm, or 400 nm, or 450 nm, or 500 nm, or 750 nm, or 1000 nm, or 1500 nm, or 2000 nm. Figure 1 In the illustrated implementation, the auxiliary layer is disposed between the first intermediate ORU (10c) and the second intermediate ORU (10d).

[0032] In some respects, the auxiliary layer (13c) may be positioned between the first group and the second group, the first group comprising a first terminal ORU (10a) and a first intermediate ORU (10c), and the second group comprising a second terminal ORU (10b) and a second intermediate ORU (10d), as shown below. Figure 1 As shown. The first group, including 10a and 10c, may have a negative ORU thickness slope, while the second group, including 10d and 10b, may have a positive slope. Alternatively, the first group may have a positive slope, and the second group may have a negative slope.

[0033] Figure 4A and Figure 7The average light transmittance of a multilayer optical film according to some embodiments is shown. A multilayer optical film (200) comprising at least a plurality of ORUs (10) collectively transmits light at an incident angle (a1) of at least one of 0°, 15°, 30°, 45°, 55°, and 60°, the plurality of ORUs having alternating first polymer optical layers (11) and second polymer optical layers (12). For substantially collimated and substantially perpendicular incident light (20), the plurality of ORUs transmit at least 60% of the light, which is averaged over a visible wavelength range (21) continuously extending from about 420 nm to about 680 nm, and averaged over mutually orthogonal first (x-axis) and second (y-axis) polarization states. In some cases, the plurality of ORUs may transmit at least 65%, or 70%, or 75%, or 80%, or 90% of the incident light, which is averaged over the visible wavelength range (21) over mutually orthogonal first (x-axis) and second (y-axis) polarization states. When the incident angle (a1) of the incident light (20) increases from substantially perpendicular to a second incident angle greater than about 35°, or 40°, or 45°, or 50°, or 55°, the average light transmittance of the plurality of ORUs remains greater than about 60%, or greater than about 65%, or greater than about 70%, which is averaged over the visible wavelength range (21) and over the first (x-axis) polarization state and the second (y-axis) polarization state.

[0034] In some embodiments, for substantially collimated incident light (20), and as the incident angle (a1) of the incident light increases from a first incident angle of less than about 10° to a second incident angle of greater than about 35°, the average light transmittance of the plurality of ORUs remains greater than about 50%, which is averaged over a visible wavelength range (21) continuously extending from about 420 nm to about 680 nm, and averaged over mutually orthogonal first (x-axis) polarization states and second (y-axis) polarization states. In some cases, the first incident angle may be less than 8°, or 6°, or 4°, or 2°, or less than 1°, the second incident angle may be greater than about 40°, or 45°, or 50°, or 55°, and the average light transmittance of the multiple ORUs may be greater than about 55%, or 60%, or 65%, or 70%, which is averaged over a visible wavelength range (21) continuously extending from about 420 nm to about 680 nm, and averaged over a first (x-axis) polarization state and a second (y-axis) polarization state that are orthogonal to each other.

[0035] According to some aspects, a multilayer optical film (200) collectively transmits at least 40% of substantially collimated, substantially perpendicular incident light (20), which is averaged over an infrared wavelength range (23) continuously extending from about 1300 nm to about 1600 nm, and averaged over a first polarization state and a second polarization state. In some cases, multiple ORUs may transmit at least 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85% of the incident light within an infrared wavelength range (23) continuously extending from about 1300 nm to about 1600 nm. When the incident angle (a1) of the incident light (20) increases from substantially perpendicular to a second incident angle greater than about 35°, or 40°, or 45°, or 50°, or 55°, the average light transmittance of the plurality of ORUs remains greater than about 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, which is averaged over an infrared wavelength range (23) continuously extending from about 1300 nm to about 1600 nm, and averaged over a first polarization state and a second polarization state.

[0036] The optical film according to this disclosure provides very high reflectivity and very low absorptivity across an angle of 0 to 55 degrees in the near (first) infrared wavelength range (22) extending from about 800 nm to about 1100 nm. For example, for substantially collimated, substantially perpendicular incident light (20), at least 70%, or 75%, or 80%, or 85%, or 90%, or 95%, or 99%, or 99.5% of the incident light (20) is not transmitted within the first infrared wavelength range (22) continuously extending from about 800 nm to about 1100 nm and is reflected by multiple ORUs. Measurements are made according to optical density, such as... Figure 4CAs shown, for substantially collimated, substantially perpendicular incident light (20) (averaged over an infrared wavelength range (22) continuously extending from about 800 nm to about 1100 nm, and averaged over a first polarization state and a second polarization state), an optical film (200) comprising a plurality of ORUs (10) may have an average optical density greater than about 3, or 3.5, or 4, or 4.5, or 5, or 5.5. In another embodiment of the optical film, for substantially collimated, substantially perpendicular incident light (20) (averaged over an infrared wavelength range (22) continuously extending from about 800 nm to about 1100 nm, and averaged over a first polarization state and a second polarization state), a plurality of ORUs (10) may have an average optical density greater than about 6, or 6.5, or 7, or 7.5, or 8, or 8.5. When the incident angle (a1) of the incident light (20) increases from substantially perpendicular to a second incident angle greater than about 35°, or 40°, or 45°, or 50°, or 55°, the average optical density of the plurality of ORUs remains greater than about 3, or 3.5, or 4, or 4.5, or 5, or 5.5, or 6, or 6.5, or 7, or 7.5, or 8, or 8.5, which is averaged over an infrared wavelength range (22) continuously extending from about 800 nm to about 1100 nm, and averaged over a first polarization state and a second polarization state.

[0037] In some embodiments, for substantially collimated incident light (20), and as the incident angle (a1) increases from a first incident angle less than about 10° to a second incident angle greater than about 35°, the average optical density of the plurality of ORUs remains greater than about 5, which is averaged over a first infrared wavelength range (22) continuously extending from about 800 nm to about 1100 nm, and averaged over a first polarization state and a second polarization state. In some cases, the first incident angle may be less than 8°, or 6°, or 4°, or 2°, or less than 1°, the second incident angle may be greater than about 40°, or 45°, or 50°, or 55°, and the average optical density of the plurality of ORUs may remain greater than about 5.5, or 6, or 6.5, or 7, or 7.5, or 8, or 8.5.

[0038] like Figure 4CAs shown, the optical film's wavelength-variable average optical density (30) across mutually orthogonal first (p) polarization and second (s) polarization includes a high optical density region (31). The high optical density region (31) is positioned within a wavelength-of-interest region (24), which extends continuously between approximately 600 nm and approximately 1400 nm. The wavelength-of-interest region (24) may vary depending on the intended application. The high optical density region (31) may have a width of at least 200 nm, 220 nm, or 240 nm, or 260 nm, or 280 nm, or 300 nm, or 350 nm. In some optical film embodiments, the average optical density of the high optical density region (31) may be greater than approximately 3, or 3.5, or 4, or 4.5, or 5. In some other optical film embodiments, the average optical density of the high optical density region (31) may be greater than approximately 5.5, or 6, or 6.5, or 7, or 7.5, or 8, or 8.5. The average optical density can be averaged over the high optical density region and over the first (p) polarization state and the second (s) polarization state.

[0039] Table 2 shows the average light transmittance of different optical film configurations (OF1, OF2, OF3) according to some embodiments of the present disclosure for the following: a visible wavelength range extending from about 420 nm to about 680 nm, a first infrared wavelength range extending from about 800 nm to 1100 nm, and a second infrared wavelength range extending from about 1300 nm to 1600 nm, and incident angles of 0°, 45°, and 55° (see Table 2). Figure 4A ).

[0040]

[0041] Table 3 shows the average optical density of different optical film configurations (OF1, OF2, OF3) according to some embodiments of the present disclosure for the following: a visible wavelength range extending from about 420 nm to about 680 nm, a first infrared wavelength range extending from about 800 nm to about 1100 nm, and a second infrared wavelength range extending from about 1300 nm to about 1600 nm, as well as incident angles of 0°, 45°, and 55° (see [reference]). Figure 4C ).

[0042]

[0043] Figures 5A to 5B The optical density along the left and right band edges of different optical films is illustrated graphically as a function of wavelength. Optical films according to one or more embodiments of this disclosure provide sharp left and right band edges to minimize the amount of visible light reflected at all angles. For example, Figure 5AA high optical density region is shown, defined by a left band edge (32a) of substantially perpendicular incident light and a left band edge (32b) of light incident at a second incident angle greater than about 35°, or 40°, or 45°, or 50°, or 55°. The optical density along the left band edges (32a, 32b) generally increases with increasing wavelength. Figure 5B The region of optical density is shown, defined by opposing right-band edges (33a) of substantially perpendicular incident light and opposing right-band edges (33b) of light incident at a second incident angle greater than about 35°, or 40°, or 45°, or 50°, or 55°. The optical density along the right-band edges (33a, 33b) generally decreases with increasing wavelength.

[0044] refer to Figure 5A For substantially perpendicular incident light, or for a first incident angle (a1) less than about 10°, or 8°, or 6°, or 4°, or 2°, or 1°, at least across a wavelength range where the optical density increases from about 1 to about 3.5, or 4, or 4.5, or 5, or 5.5, or 6, a first optimal linear fit (34a) to the left band edge (32a) has a positive slope (35a) greater than about 6% / nm, or greater than about 8% / nm, or greater than about 9% / nm, or greater than about 10% / nm. In some embodiments, the first optimal linear fit (34a) has an r-squared value greater than about 0.8, or greater than about 0.9, or greater than about 0.95, or greater than about 0.98.

[0045] For incident angles of light greater than approximately 35°, or 40°, or 45°, or 50°, or 55°, the first optimal linear fit (34b) has a positive slope (35b) that increases by at least 10%, or at least 15%, or at least 20%, or 25%, or 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%. In some cases, the positive slope (35b) of the linear fit (34b) at the second incident angle may be greater than approximately 10% / nm, or approximately 11% / nm, or approximately 12% / nm, or approximately 13% / nm, or approximately 15% / nm, or approximately 16% / nm, or approximately 17% / nm. The r-squared value of the first optimal linear fit (34b) is greater than approximately 0.8, or greater than approximately 0.9, or greater than approximately 0.95, or greater than approximately 0.98.

[0046] refer to Figure 5BThe second best linear fit (36a) for the right-side edge (33a) has a negative slope (37a) for at least a wavelength range where the optical density increases from about 1 to about 3.5, 4, 4.5, 5, 5.5, or 6. For the first incident angle, this negative slope has a value greater than about 0.06 / nm or 0.07 / nm. When the incident angle (a1) increases to a second incident angle greater than about 35°, 40°, 45°, 50°, or 55°, the value of the negative slope (37a) of the second best linear fit increases by at least 10%, at least 15%, at least 20%, at least 25%, or at least 30%. In some cases, the value of the slope of the second best linear fit at the second incident angle may be greater than about 0.07 / nm, 0.08 / nm, 0.09 / nm, or 0.10 / nm. The second best linear fit (36a) has an r-squared value greater than about 0.8, or greater than about 0.9, or greater than about 0.95, or greater than about 0.98.

[0047] Figure 6A A system (300) including an optical film (200) according to one or more embodiments of the present disclosure is shown. The system (300) includes a housing (310) defining an opening (320) for allowing visible light to pass through. In some applications, the housing may be the cab (310) of a vehicle (301), and the opening (320) may be defined in the roof (302) of the vehicle (301). The optical film (200) may be disposed on the opening (320) to cover the opening (320). A light source (330) emits a first light (340) and a second light (350), the first light having a wavelength in a visible wavelength range (21) continuously extending from about 420 nm to about 680 nm, and the second light having a wavelength in a high light density region (31, Figure 4C The wavelength in the first incident angle (b1) is specified. For all incident angles between the first and second incident angles (b1), the optical film (200) transmits at least 60% of the first light and reflects at least 99% of the second light. In some aspects, for all incident angles between the first and second incident angles (b1), the optical film (200) transmits at least 65%, or 70%, or 75%, or 80%, or 90% of the first light. In some aspects, for all incident angles between the first and second incident angles (b1), the optical film (200) reflects at least 99.5%, or 99.9%, or 99.99%, or 99.999% of the second light.

[0048] Unless otherwise indicated, the description of elements in the accompanying drawings should be understood to apply equally to corresponding elements in the other drawings. While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent embodiments may be used instead of the illustrated and described embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications, variations, or combinations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An optical film comprising a plurality of optical repeating units (ORUs), the plurality of ORUs being co-extruded and co-stretched together and totaling at least 15, each ORU having an average physical thickness of less than about 1000 nm and comprising at least two distinct polymer layers, the ORUs including a first and a second terminal ORU that are furthest apart from each other. For a first intermediate ORU and a second intermediate ORU among the plurality of ORUs, the first intermediate ORU and the second intermediate ORU are spaced apart from each of the first last ORU and the second last ORU by at least 10 other ORUs among the plurality of ORUs, the first intermediate ORU and the second intermediate ORU are spaced apart from each other by no more than about 5 other ORUs among the plurality of ORUs and have corresponding average physical thicknesses H1 and H2, the magnitude of (H1-H2) / ((H1+H2) / 2) is greater than about 1%, and Such that, for substantially collimated, substantially perpendicular incident light, the plurality of ORUs have: At least 60% average light transmittance, said average light transmittance being averaged over a visible wavelength range continuously extending from about 420 nm to about 680 nm, and being averaged over mutually orthogonal first and second polarization states; and An average optical density greater than about 3, the average optical density being averaged over a first infrared wavelength range continuously extending from about 800 nm to about 1100 nm, and being averaged over the first polarization state and the second polarization state.

2. The optical film of claim 1, wherein when the incident angle of the incident light increases from substantially perpendicular to a second incident angle greater than about 35 degrees, the average light transmittance of the plurality of ORUs remains greater than about 60%, the average light transmittance being averaged over the visible wavelength range and over the first polarization state and the second polarization state.

3. The optical film of claim 1, wherein when the incident angle of the incident light increases from substantially perpendicular to a second incident angle greater than about 35 degrees, the average optical density of the plurality of ORUs remains greater than about 3, the average optical density being averaged over the first infrared wavelength range and over the first polarization state and the second polarization state.

4. The optical film of claim 1, wherein for the substantially collimated, substantially perpendicular incident light, the optical film's wavelength-averaged optical density on the first polarization and the second polarization includes a high optical density region, the high optical density region being at least 200 nm wide, having an average optical density greater than about 3, and disposed in a region of interest wavelengths continuously extending between about 600 nm and about 1400 nm.

5. The optical film of claim 4, wherein the high optical density region is defined by a left band edge and an opposite right band edge, the optical density along the left band edge generally increases with increasing wavelength, the optical density along the right band edge generally decreases with increasing wavelength, and wherein a first optimal linear fit to the left band edge has a slope greater than about 0.06 / nm, at least across a wavelength range in which the optical density increases from about 1 to about 3.

5.

6. The optical film of claim 5, wherein when the incident angle of the incident light increases from substantially perpendicular to a second incident angle greater than about 35 degrees, the slope of the first best linear fit increases by at least 10%.

7. An optical film comprising a plurality of optical repeating units (ORUs), the plurality of ORUs being co-extruded and co-stretched together and totaling at least 15, each ORU having an average physical thickness of less than about 1000 nm and comprising at least two distinct polymer layers, such that for substantially collimated incident light, and when the incident angle of the incident light increases from a first incident angle of less than about 10 degrees to a second incident angle of greater than about 35 degrees: The average optical transmittance of the plurality of ORUs remains greater than approximately 50%, and the average optical transmittance is averaged over a visible wavelength range continuously extending from approximately 420 nm to approximately 680 nm, and is averaged over mutually orthogonal first and second polarization states; and The average optical density of the plurality of ORUs is maintained at greater than about 5, and the average optical density is averaged over a first infrared wavelength range that extends continuously from about 800 nm to about 1100 nm, and is averaged over the first polarization state and the second polarization state.

8. An optical film comprising a plurality of optical repeating units (ORUs), the plurality of ORUs being co-extruded and co-stretched together and totaling at least 15, each ORU having an average physical thickness of less than about 1000 nm and comprising at least two distinct polymer layers, such that, for substantially collimated incident light, the wavelength-varying average optical density of the optical film across a first and second mutually orthogonal polarization includes a high optical density region, the high optical density region being at least 200 nm wide, having an average optical density greater than about 3 when averaged across the high optical density region and across the first and second polarization states. And located in a region of interest wavelengths that extends continuously between about 600 nm and about 1400 nm, the high optical density region is defined by a left band edge and an opposite right band edge, the optical density along the left band edge generally increases with increasing wavelength, and the optical density along the right band edge generally decreases with increasing wavelength, wherein at least across the wavelength range in which the optical density increases from about 1 to about 3.5, a first optimal linear fit to the left band edge has a slope, the slope being greater than about 0.06 / nm for a first incident angle less than about 10 degrees, and the slope increasing as the incident angle increases to a second incident angle greater than about 35 degrees.

9. The optical film of claim 8, wherein the second optimal linear fit to the right band edge has a negative slope at least across a wavelength range in which the optical density increases from about 1 to about 3.5, the negative slope having a value greater than about 0.06 / nm for the first incident angle, and the value increasing as the incident angle increases to the second incident angle.

10. A system comprising: A housing, the housing defining an opening for allowing visible light to pass through it; And the optical film according to claim 8, wherein the optical film is disposed on and covers the opening such that, for a light source emitting a first light having a wavelength in a visible wavelength range extending continuously from about 420 nm to about 680 nm and a second light having a wavelength in the high optical density region, and for all incident angles between the first incident angle and the second incident angle, the optical film transmits at least 60% of the first light and reflects at least 99% of the second light.

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