Multilayer optical film for lidar systems

Abstract

A one-piece optical film includes a plurality of at least first to third microlayers having different compositions. Each of the microlayers has an average thickness of less than about 500 nm. For incident light, for at least one polarization state, a visible wavelength range, a wide infrared wavelength range of at least 10 nm, a first range of angles of incidence extending from about 0 degrees to about 20 degrees, and a second range of angles of incidence extending from about 45 degrees to about 75 degrees, the integrated optical film has the following conditions: for the visible wavelength range, for the first range of angles of incidence, for the second range of angles of incidence, for the second range of angles of incidence; an average optical transmittance for each of the first range of angles of incidence and the second range of angles of incidence is greater than about 45%; and for the infrared wavelength range, an average optical transmittance for the first range of angles of incidence is less than about 20% and an average optical transmittance for the second range of angles of incidence is greater than about 45%.

Description

Technical Field

[0001] The present disclosure relates generally to optical films and optical sensing systems, and more particularly to multilayer optical films configured to be incorporated into windows and to be optically transparent for light detection and ranging (LiDAR). Background Art

[0002] Cars are increasingly becoming autonomous. For example, newer vehicles include features such as adaptive cruise control and parking assist systems that allow cars to automatically maneuver into parking spaces. Attempts are being made to create vehicles that are almost fully autonomous, requiring little direct human input to operate. Information and data surrounding an autonomous vehicle is acquired from sources external to the vehicle using sensing systems such as LiDAR and other near-infrared (NIR) sensors. Such sources external to the vehicle may include sensors connected to the vehicle ahead and oncoming vehicles, pedestrians, cyclists, etc., and also include sensors mounted on structures such as traffic lights, bridges, etc. The sensing system may be configured to be mounted on the outside or inside of the vehicle. Sensing systems disposed inside the cab of a vehicle prevent the sensors from being exposed to environmental conditions such as inclement weather. Summary of the invention

[0003] Some aspects of the present disclosure relate to an integrated optical film, the integrated optical film comprising a plurality of first optical repeating units totaling at least 10, the plurality of first optical repeating units being disposed on a plurality of second optical repeating units totaling at least 10 and separated from the plurality of second optical repeating units by at least one spacer layer. Each of the first optical repeating units has at least microlayers A1 and B1 of different compositions. Each of the second optical repeating units has at least microlayers A2, B2, and C2 of different compositions. At least one of the microlayers A1 and B2 has a composition different from at least one of the microlayers A2, B2, and C2. Each of the microlayers in the first optical repeating unit and the second optical repeating unit has an average thickness of less than about 500 nm. Each of the at least one spacer layer has an average thickness of greater than about 500 nm. For incident light, for at least one polarization state, a visible wavelength range extending from about 420 nm to about 680 nm, an infrared wavelength range at least 10 nm wide and within 750 nm to 1000 nm, a first incident angle range extending from about 0 degrees to about 20 degrees, and a second incident angle range extending from about 45 degrees to about 75 degrees, the integrated optical film has the following conditions: for the visible wavelength range, the average optical transmittance for each of the first incident angle range and the second incident angle range is greater than about 45%; and for the infrared wavelength range, the average optical transmittance for the first incident angle range is less than about 20%, and the average optical transmittance for the second incident angle range is greater than about 45%. The integrated optical film has an integrated construction.

[0004] Some other aspects of the present disclosure relate to an integrated optical film comprising a plurality of at least first to third microlayers having different compositions and a total number of at least 20. Each of the at least first to third microlayers has an average thickness of less than about 500 nm. For incident light, for at least one polarization state, a first incident angle range extending from about 0 degrees to at least about 40 degrees, and an air mass of 1.5 and a normalized solar spectrum normalized over a sunlight wavelength range that includes at least a visible wavelength and a first infrared wavelength range, the normalized solar spectrum has average relative intensities Sv and Si1 in the corresponding visible wavelength range and the first infrared wavelength range, and the integrated optical film has average optical transmittances Tv and Ti1 in the corresponding visible wavelength range and the first infrared wavelength range, the visible wavelength range extends from about 420nm to about 680nm, the first infrared wavelength range is at least 50nm wide and is within 800nm ​​to 2500nm, wherein Sv>Si1≥0.2, Tv / Ti1≥1.4.

[0005] Some other aspects of the present disclosure relate to an integrated optical film comprising a plurality of at least first to third microlayers having different compositions and a total number of at least 20. Each of the at least first to third microlayers has an average thickness of less than about 500 nm. For incident light, for at least one polarization state, a first incident angle range extending from about 0 degrees to at least about 40 degrees and an air mass of 1.5 and a normalized solar spectrum normalized on a sunlight wavelength range including a visible wavelength range and at least non-overlapping first infrared wavelength range, second infrared wavelength range and third infrared wavelength range, the normalized solar spectrum and the integrated optical film have corresponding average relative intensities Sv, Si1, Si2 and Si3 and average optical transmittances Tv, Ti1, Ti2 and Ti3 in the corresponding visible wavelength range and the first to the third infrared wavelength range, the visible wavelength range extends from about 420nm to about 680nm, the at least non-overlapping first infrared wavelength range, second infrared wavelength range and third infrared wavelength range are within 800nm ​​to 2500nm, have corresponding average relative intensities Si1, Si2 and Si3 and are each at least 40nm wide, wherein Sv>Si1>Si2>Si3≥0.1, each of Tv / Ti1 and Tv / Ti3 is greater than 1.4, and Tv / Ti2≤2.5.

[0006] Some aspects of the present disclosure relate to an integrated optical film, the integrated optical film including a plurality of at least first to third microlayers, the plurality of at least first to third microlayers having different compositions and a total number of at least 20. Each of the at least first to third microlayers has an average thickness of less than about 500 nm. For incident light incident on the integrated optical film at a first angle of incidence of less than about 10 degrees and for at least one polarization state, the relationship between the optical transmittance of the integrated optical film and the wavelength includes a first transmission band, the first transmission band includes at least most wavelengths in a visible wavelength range extending from about 420 nm to about 680 nm. A first transmission stop band is disposed between the first transmission band and the second transmission band and includes at least most wavelengths in a first infrared wavelength range extending from about 700 nm to about 950 nm. A second infrared transmission stop band is disposed adjacent to a second transmission band opposite the first transmission stop band and includes at least some wavelengths in a second infrared wavelength range extending from about 1200 nm to about 1300 nm. For the visible wavelength range and the second infrared wavelength range, the integrated optical film has corresponding average optical transmittances Tv and Ti for the first incident angle, and has corresponding average optical transmittances Tv' and Ti' for a second incident angle greater than about 30 degrees, wherein Tv and Tv' are within 30% of each other, and Ti is at least 1.3 times larger than Ti'.

[0007] Some aspects relate to an optical construct that includes the integrated optical film of one or more embodiments of the present disclosure bonded to at least one bonding layer.

[0008] Other aspects of the present disclosure relate to a windshield of a vehicle, the windshield including an integrated optical film of one or more embodiments of the present disclosure, the integrated optical film being disposed between and bonded to a first substrate and a second substrate.

[0009] Some other aspects of the present disclosure relate to an optical sensing system including a windshield of a vehicle and a transceiver including at least one of a transmitter and a receiver and configured to at least one of transmit and receive first light passing through the windshield toward an object along a propagation direction in air at a first angle to a normal to the windshield. The first angle is greater than about 20 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various aspects of the present disclosure will be discussed in more detail with reference to the accompanying drawings, in which:

[0011] Figure 1 schematically illustrates an integrated multilayer optical film according to some embodiments of the present disclosure;

[0012] Figures 2 to 3 Graphically shows the transmission spectra of different optical film configurations at different wavelengths and incident angles;

[0013] Figure 4 The normalized solar intensity and transmission spectra of different optical film configurations at different wavelengths over an incident angle range of 0 to 85 degrees are graphically shown;

[0014] Figures 5 and 6 Schematically illustrates a windshield of a vehicle including an integrated optical film according to one or more embodiments of the present disclosure;

[0015] Figure 7 schematically illustrates an optical sensing system according to some embodiments of the present disclosure;

[0016] Figure 8 graphically illustrates the transmission spectra of optical films according to some embodiments at different wavelengths and incident angles; and

[0017] 9A to 9D , FIG. 10A to FIG. 10D , Figures 11 to 14 The number of layers and layer thicknesses for different microlayer stacks with different compositions are graphically represented.

[0018] The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it should be understood that the use of a number to refer to a component in a given figure is not intended to limit the component labeled with the same number in another figure. DETAILED DESCRIPTION

[0019] In the following description, reference is made to the accompanying drawings, which form a part of the present disclosure and in which various embodiments are shown by way of example. It should be understood that other embodiments may be conceived and carried out without departing from the scope or essence of the present specification. Therefore, the following specific embodiments should not be considered to have a limiting meaning.

[0020] Active driver assistance systems such as adaptive cruise control and land-holding assist have become common in recent vehicles. In recent years, vehicles equipped with more advanced autonomous driving features are also being developed. Therefore, the demand for integrating more sensors in vehicles will continue to grow. Specifically, LiDAR systems have been adopted by many automobile manufacturers to implement driver assistance and autonomous driving features. In most prototype vehicles, the LiDAR system is installed on the outside. But for aesthetic and practical reasons (such as protection from bad weather), moving the LiDAR unit inside the vehicle behind the windshield has many advantages.

[0021] One of the challenges of LiDAR mounted inside the windshield is that the car windshield is not transparent to the LiDAR wavelength because it is designed to reflect and / or absorb in the LiDAR wavelength that is common to the LiDAR wavelength used for solar thermal emission. One solution to this problem is to create a cutout in the car windshield. Another solution is to use IR transparent glass. Creating a physical cutout is a major obstacle that requires significant changes and adjustments in the windshield manufacturing process. In any of the above solutions, there will be no solar thermal emission in the LiDAR cabin, which may cause excessive heat and damage sensitive electronics. The embodiments described herein address these and other challenges.

[0022] Embodiments of the present disclosure describe multilayer optical films (MOFs) that are transparent to mainstream LiDAR operating wavelengths (e.g., 905 nm) while maintaining the solar heat rejection performance of automotive windshields. Embodiments disclosed herein eliminate the need for physical cutouts in the windshield and provide solar protection for both the cabin and the LiDAR cabin.

[0023] like Figure 5 and Figure 6As shown, a vehicle (301) may include a window (300) configured as an optically transparent window. For example, the window (300) may be a front windshield of the vehicle (301). An integrated optical construction (210) including an integrated optical film (200) according to one or more embodiments of the present disclosure may be configured to be incorporated into the window (300).

[0024] In some embodiments, the integrated optical film (200) may be embedded in a window. In other embodiments, the integrated optical film (210) may be bonded to a first bonding layer (92) that is configured to bond to a first substrate (90) of the window (300). For example, the first substrate (90) may include glass. The integrated optical film (200) may be substantially coextensive with the first bonding layer (92) in length and width. In other aspects, the integrated optical film (200) may also be bonded to a second bonding layer (93) opposite the first bonding layer (92), such that the integrated optical film (200) is disposed between the first bonding layer (92) and the second bonding layer (93) and bonded to the first bonding layer and the second bonding layer. The second bonding layer (93) may be configured to bond to a second substrate (91) of the window (300). For example, the second substrate (91) may include glass. The integrated optical film (200) may be substantially coextensive with the second bonding layer (93) in length and width.

[0025] In some aspects, at least one of the first bonding layer (92) and the second bonding layer (93) may include one or more of polyvinyl butyral (PVB), pressure sensitive adhesive (PSA), ethylene vinyl acetate (EVA), polyolefin, and polyurethane. In some aspects, for an infrared wavelength range (e.g., 885 nm to 925 nm), each of the first bonding layer (92) and the second bonding layer (93) may have an average optical transmittance of greater than about 60%, greater than about 70%, greater than about 80%, or greater than about 90% for each of a first incident angle range extending from about 0 degrees to about 20 degrees and a second incident angle range extending from about 45 degrees to about 75 degrees.

[0026] The integrated optical film (200) has an integrated structure. Figure 1 The construction of an integrated optical film (200) according to some embodiments is described.

[0027] The integrated optical film (200) includes a plurality of at least first to third microlayers (A1, B1, C1, A2, B2, C2) with a total number of at least 20, or 50, or 100, or 150, or 200, or 250, or 300, or 350, or 400, or 450, or 500. In some embodiments, the integrated optical film (200) may include a plurality of first and second optical repeating units (10, 30). Each first optical repeating unit in the plurality of first optical repeating units (10) may include at least microlayers A1 and B1, and each second optical repeating unit in the plurality of second optical repeating units (30) may include at least microlayers A2, B2, and C2. The first optical repeating unit (10) may be disposed on the second optical repeating unit (30).

[0028] In some aspects, the first optical repeating unit (10) can be separated from the second optical repeating unit (30) by at least one spacer layer (20, 21). The spacer layer (20, 21) can have an average thickness greater than about 500 nm, or greater than about 550 nm, or greater than about 600 nm, or greater than about 650 nm, or greater than about 700 nm, or greater than about 800 nm, or greater than about 900 nm, or greater than about 1000 nm.

[0029] In some aspects, the total number of the plurality of first optical repeating units (10) can be at least 10, or 15, or 20, or 50, or 100, or 200, or 300, or 400, or 500. The total number of the plurality of second optical repeating units (30) can be at least 10, or 15, or 20, or 50, or 100, or 200, or 250, or 300.

[0030] Microlayers A1, B1, C1, A2, B2, C2 may include different compositions. In some aspects, at least one of microlayers A1 and B2 may have a different composition than at least one of microlayers A2, B2, and C2. Each of the microlayers in the first and second optical repeat units (10, 30) may have an average thickness of less than about 500 nm, or less than about 450 nm, or less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm.

[0031] Different designs of microlayer stacks (multilayer optical films (MOFs)) are proposed that are transparent to visible light signals and LiDAR signals while reflecting sunlight IR energy. The transparent window for LiDAR signals is centered at about 905 nm (+ / - 20 nm) for incident angles from at least about 40° to about 85° to accommodate typical windshield configurations and LiDAR scanning angles.

[0032] In some embodiments, the materials of the plurality of microlayers may have different refractive indices. For example, the microlayers may have a stack including a copolymer of PET and PMMA (coPMMA) or any other polymer with a low refractive index (including copolyesters, fluorinated polymers, or combinations thereof).

[0033] In one embodiment, if 9A to 9D and FIG. 10A to FIG. 10D As best shown, the plurality of at least first through third microlayers includes a plurality of alternating microlayers A1 and B1 totaling at least 5, or 10, or 15, or 20, or 50, or 100, or 200, or 250, or 300, or 350, or 400 microlayers disposed on a plurality of alternating microlayers A2, C2, B2, and C2 totaling at least 10, or 15, or 20, or 50, or 100, or 200, or 300, or 400, or 500. Microlayers A1 and B1 can have different compositions, and microlayers A2, B2, and C2 can have different compositions. At least one of microlayers A1 and B1 can have a different composition than at least one of microlayers A2, B2, and C2. Each of microlayers A1, B1, A2, B2, and C2 can have an average thickness of less than about 500 nm, or less than about 450 nm, or less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm.

[0034] In one aspect, microlayers A1 and A2 can have the same composition, and microlayers B1 and B2 can have the same composition. Fig.9A and Fig. 10AThe MOF design shown can combine a quarter-wavelength A1-B1 MOF (e.g., polyethylene terephthalate (PET)-copolymer of polymethyl methacrylate (CoPMMA)) with an A2-B2-C2 MOF (e.g., PET-CoPMMA-ethylene glycol-modified PET (PETg)) to produce two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths. At least a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer A2, and at least a majority of the microlayers in microlayer B1 can be thicker than at least a majority of the microlayers in microlayer B2. In some examples, a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer B1. In some examples, at least a majority of the microlayers in microlayer B2 can be thicker than at least a majority of the microlayers in microlayer B2. The microlayers can be thinner than at least a majority of the microlayers in microlayer C2, and at least a majority of the microlayers in microlayer C2 can be thinner than at least a majority of the microlayers in microlayer A2. At least one spacer layer (20, 21) can be disposed between the plurality of alternating microlayers A1-B1 and the plurality of alternating microlayers A2-C2-B2-C2. Each of the at least one spacer layer has an average thickness greater than about 500 nm, or 550 nm, or 600 nm, or 650 nm, or 700 nm, or 800 nm, or 900 nm, or 1000 nm.

[0035] In another aspect, microlayers A1 and A2 can have the same composition, and microlayers B1 and C2 can have the same composition. Fig. 9B and Fig. 10B As shown, the MOF design can combine a quarter-wavelength A1-B1 MOF (e.g., PET-CoPMMA) with an A2-C2-B2-C2 MOF (e.g., PET-CoPMMA-vinylidene fluoride (THV)-CoPMMA) to produce two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths. THV is available from 3M Company, St. Paul, MN, under the brand name Dyneon TM THV can be used as a low refractive index material in the A2-C2-B2-C2 stack to take advantage of its low refractive index (n is about 1.37). In some examples, at least a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer A2, and at least a majority of the microlayers in microlayer B1 can be thicker than at least a majority of the microlayers in microlayer C2. In other examples, at least a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer B1. At least a majority of the microlayers in microlayer B2 can be thinner than at least a majority of the microlayers in microlayer A2, and at least a majority of the microlayers in microlayer C2 can be thinner than at least a majority of the microlayers in microlayer B2. At least one spacer layer (20, 21) can be disposed between the plurality of alternating microlayers A1-B1 and the plurality of alternating microlayers A2-C2-B2-C2.

[0036] In another aspect, microlayers A1, A2, B1, B2, and C2 have different compositions. For example, at least one of microlayer A1 and microlayer B1 is an inorganic layer. Microlayer A1 may include Nb2O5, or, in some examples, SiON. Microlayer B1 may include acrylate. For example, Fig. 9C and Fig. 10C As shown, the MOF design can combine an inorganic quarter-wavelength A1-B1 stack (e.g., Nb2O5-acrylate) with an A2-C2-B2-C2 MOF (e.g., PET-PETg-CoPMMa-PETg) to produce two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths.

[0037] In such Fig.9D and Fig. 10D In another example shown, a MOF design can combine an inorganic quarter-wavelength A1-B1 stack (e.g., SiON / acrylate) with an A2-C2-B2-C2 MOF stack (e.g., PET-PETg-CoPMMA-PETg) to create two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths. SiON (n is approximately 2.03) has a slightly lower refractive index than Nb2O5 (n is approximately 2.33), which results in a narrower intrinsic bandwidth. The narrower bandwidth helps manage color artifacts at large angles. In some cases, the total number of alternating microlayers A1-B1 can be less than 50, or 45, or 40, or 35, or 35, or 20, and the total number of alternating microlayers A2-C2-B2-C2 can be at least 200, or 300, or 400, or 500, or 600, or 700, or 800, or 900, or 1000, or 1200. At least a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer A2, and at least a majority of the microlayers in microlayer B1 can be thicker than at least a majority of the microlayers in microlayer B2. In some cases, a majority of the microlayers in microlayer A1 can be thinner than a majority of the microlayers in microlayer B1. In other cases, at least a majority of the microlayers in microlayer B2 can be thinner than at least a majority of the microlayers in microlayer C2, and at least a majority of the microlayers in microlayer C2 can be thinner than at least a majority of the microlayers in microlayer A2.

[0038] In one embodiment, if Fig.11As shown, the plurality of at least the first to third microlayers include a plurality of alternating microlayers A1-C1-B1-C1 having a total number of at least 50, or 100, or 150, or 200, or 250, or 300, or 350, or 400, or 450, or 500, or 550, or 600 disposed on a plurality of alternating microlayers A2-C2-B2-C2 having a total number of at least 200, or 300, or 400, or 500, or 600, or 700, or 800, or 900, or 1000, or 1200, or 1400, or 1600. Fig.12 As shown, microlayers A1, B1, and C1 can have different compositions, and microlayers A2, B2, and C2 can have different compositions. In some aspects, at least one of microlayers A1, B1, and C1 can have a different composition than at least one of microlayers A2, B2, and C2. In some cases, microlayers A1 and A2 can have the same composition, microlayers B1 and B2 have the same composition, and microlayers C1 and C2 have the same composition. For example, microlayers A1 and A2 can include PET, microlayers B1 and B2 can include CoPMMA, and microlayers C1 and C2 can include PETg. For example, a MOF design can include two ACBC MOF stacks (e.g., PET-PETg-CoPMMA-PETg) to produce two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths.

[0039] Each of microlayers Al, B1, C1, A2, B2, and C2 can have an average thickness of less than about 500 nm, or less than about 450 nm, or less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm. At least a majority of the microlayers in microlayer Al can be thinner than at least a majority of the microlayers in microlayer A2, at least a majority of the microlayers in microlayer B1 can be thicker than at least a majority of the microlayers in microlayer B2, and at least a majority of the microlayers in microlayer C1 can be thinner than at least a majority of the microlayers in microlayer C2. In some examples, a majority of the microlayers in microlayer Al can be thinner than a majority of the microlayers in microlayer B1, and a majority of the microlayers in microlayer C1 can be thinner than a majority of the microlayers in microlayer Al. In other examples, at least a majority of the microlayers in microlayer B2 can be thinner than at least a majority of the microlayers in microlayer C2, and at least a majority of the microlayers in microlayer C2 can be thinner than at least a majority of the microlayers in microlayer A2. At least one spacer layer (20, 21) may be disposed between the plurality of alternating microlayers A1, C1, B1, and C1 and the plurality of alternating microlayers A2, C2, B2, and C2.

[0040] In one embodiment, if Fig.13As shown, the plurality of at least first to third microlayers may include a plurality of alternating microlayers A1 and B1 having a total number of at least 50, or 75, or 100, or 125, or 150, or 175, or 200 disposed on a plurality of alternating microlayers A2-B3-A3-B2-A3-B3 having a total number of at least 100, or 200, or 300, or 400, or 500, or 600. Microlayers A1 and B1 may have different compositions. Microlayers A2 and A3 may have substantially the same composition and different thicknesses. Microlayers B2 and B3 may have substantially the same composition and different thicknesses. At least one of microlayers A1 and B1 may have a different composition than at least one of microlayers A2 and B2. Fig.14 As shown, in some aspects, microlayers A1 and A2 can have the same composition, and microlayers B1 and B2 can have the same composition. At least a majority of the microlayers in microlayer A1 can be thinner than at least a majority of the microlayers in microlayer B2, and at least a majority of the microlayers in microlayer B1 can be thicker than at least a majority of the microlayers in microlayers A3 and B3. For example, microlayers A1 and A2 can include PET, and microlayers B1 and B2 can include CoPMMA. At least one spacer layer (20, 21) can be disposed between the plurality of alternating microlayers A1-B1 and the plurality of alternating microlayers A2-B3-A3-B2-A3-B3.

[0041] Each of microlayers Al, Bl, A2, B2, A3, and B3 can have an average thickness of less than about 500 nm, or less than about 450, or less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm. At least a majority of the microlayers in microlayer Al can be thinner than at least a majority of the microlayers in microlayer Bl. In some cases, at least a majority of the microlayers in microlayer A3 can be thinner than at least a majority of the microlayers in microlayer A2, and at least a majority of the microlayers in microlayer B3 can be thinner than at least a majority of the microlayers in microlayer B2.

[0042] Other designs of optical films may include metal / dielectric / metal (Ag / ITO / Ag) stacks to produce a wide reflection band in the NIR spectrum while maintaining a reasonable level of transmission at 905nm for LiDAR operation. Some embodiments of the optical film design combine a quarter-wavelength AB MOF (PET / CoPMMA) with a 7-11MOF (PET / CoPMMA) to produce two reflection bands in the NIR spectrum and open a spectral window for the LiDAR wavelength. 7-11MOF refers to a layer structure in which a high refractive index layer (H) and a low refractive index layer (L) are arranged in a 6-layer repeating unit cell with a film thickness ratio of HLHLHL=7:1:1:7:1:1. For example, a multilayer optical film having such a layer structure is described in U.S. Patent No. 5,360,659 to Arends et al.

[0043] To extend the reflection band into the infrared spectrum beyond 1200 nm, ACBC and 7-11MOF unit cell structures can be used to suppress higher order harmonics in the visible spectrum. In other embodiments, the optical film design can combine MOF-AB stacks (PET / CoPMMA) with inorganic 7-11 stacks (SiON / acrylate) to produce two reflection bands in the NIR spectrum and open a spectral window for LiDAR wavelengths.

[0044] The various optical film designs disclosed herein have average optical transmittances in a visible wavelength range (50) extending from about 420 nm to about 680 nm and in an infrared wavelength range (51) having a width of at least 10 nm, or 15 nm, or 20 nm, or 25 nm, or 30 nm, or 35 nm, or 40 nm and within a range of 750 nm to 1000 nm, at a first incident angle range and a second incident angle range (60, 61) as shown in FIG. Figure 2 and Figure 3 The first incident angle range (60) may extend from about 0 degrees to about 20 degrees, and the second incident angle range (61) may extend from about 45 degrees to about 75 degrees.

[0045] In some aspects, for incident light (40, Figure 1 ), for at least one polarization state (x-axis and y-axis) and for each of the first incident angle range and the second incident angle range (60, 61), the average optical transmittance of the optical film for the visible wavelength range (50) may be greater than about 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%.

[0046] In some aspects, for incident light (40, Figure 1 ), for at least one polarization state (x-axis and y-axis), the average optical transmittance of the optical film within the first incident angle range (60) for the infrared wavelength range (51) may be less than about 20%, or 15%, or 10%, or 9%, or 8%, or 7%, or 6%, or 5%, or 4%, or 3%, or 2%, or in some instances, less than about 1%.

[0047] In other aspects, for incident light (40, Figure 1 ), for at least one polarization state (x-axis and y-axis), the average optical transmittance of the optical film in the second incident angle range (61) for the infrared wavelength range (51) may be greater than about 45%, or 50%, or 55%, or 60%, or 65%, or in some instances, greater than about 70%.

[0048] In some cases, the infrared wavelength range can be within 800 nm to 950 nm. In some other cases, the infrared wavelength range can include one or more of 850 nm, 905 nm, and 940 nm.

[0049] Table 1 shows the optical transmittance of different optical film configurations (OF1, OF2...OF9) according to some embodiments of the present disclosure within a visible wavelength range extending from about 420 nm to about 680 nm and within a first incident angle range extending from about 0 degrees to about 20 degrees and a second incident angle range extending from about 45 degrees to about 75 degrees.

[0050] Table 1

[0051]

[0052] Table 2 shows the optical transmittance of different optical film configurations (OF1, OF2...OF9) according to some embodiments of the present disclosure within an infrared wavelength range extending from about 885 nm to about 925 nm and within a first incident angle range extending from about 0 degrees to about 20 degrees and a second incident angle range extending from about 45 degrees to about 75 degrees.

[0053] Table 2

[0054]

[0055] Figure 4 The average relative intensity of a normalized solar spectrum (80) and the average optical transmittance of different optical film designs at a first range of incident angles extending from about 0 degrees to at least about 40 degrees, or 45 degrees, or 50 degrees, or 55 degrees, or 60 degrees, or 65 degrees, or 70 degrees, or 75 degrees, or 80 degrees, or 85 degrees are shown. The normalized solar spectrum (80) can have an air mass of 1.5 and can be normalized over a range of solar wavelengths including at least visible wavelengths (50) and a first infrared wavelength range (52), the visible wavelength range extending from about 420 nm to about 680 nm, the first infrared wavelength range being at least 50 nm wide and within 800 nm to 2500 nm. In some examples, the first infrared wavelength range (52) can extend from about 700 nm to about 950 nm.

[0056] In some aspects, for incident light (40, Figure 1) and for at least one polarization state (x-axis and y-axis), the normalized solar spectrum (80) may have average relative intensities Sv and Si1 in the corresponding visible wavelength range (50) and the first infrared wavelength range (52). In some cases, Sv>Si1≥0.2, or Sv>Si1≥0.25, or Sv>Si1≥0.3, or Sv>Si1≥0.35, or Sv>Si1≥0.4, or Sv>Si1≥0.45, or Sv>Si1≥0.5, or Sv>Si1≥0.55, or Sv>Si1≥0.55.

[0057] In some examples, the average relative intensity Sv and Si1 are such that 1≤Sv / Si1≤2. In some examples, the average relative intensity Sv in the visible wavelength range (50) may be at least 0.05, or at least 0.1, or at least 0.15, or at least 0.2, or at least 0.25, or at least 0.3 greater than the average relative intensity Si1 in the first infrared wavelength range (52).

[0058] In some aspects, for incident light (40, Figure 1 ) and for at least one polarization state (x-axis and y-axis), the integrated optical film can have average optical transmittances Tv and Ti1 in the corresponding visible wavelength range (50) and the first infrared wavelength range (52). In some cases, Tv / Ti1≥1.4, or Tv / Ti1≥1.5, or Tv / Ti1≥1.75, or Tv / Ti1≥2, or Tv / Ti1≥2.25, or Tv / Ti1≥2.5, or Tv / Ti1≥2.75, or Tv / Ti1≥3, or Tv / Ti1≥3.25, or Tv / Ti1≥3.5.

[0059] In some examples, the average optical transmittance Tv of the integrated optical film in the visible wavelength range (50) may be such that Tv≥50%, or Tv≥55%, or Tv≥60%, or Tv≥65%, or Tv≥70%. In some examples, the average optical transmittance Ti1 of the integrated optical film in the first infrared wavelength range (52) may be such that Ti1≤30%, or Ti1≤25%, or Ti1≤20%.

[0060] In some embodiments, the normalized solar spectrum (80) may further include a second infrared wavelength range (53), which may be at least 50 nm wide and within a range of 800 nm to 2500 nm. The first infrared wavelength range (52) may be disposed between the visible wavelength range (50) and the second infrared wavelength range (53). In some examples, the second infrared wavelength range (53) may extend from about 1000 nm to about 1100 nm, such as Figure 4 shown.

[0061] The normalized solar spectrum (80) may have an average relative intensity Si2 within the second infrared wavelength range (53), such that Si2≤Si1. For the incident light, the at least one polarization state, and the first incident angle range, the integrated optical film may have an average optical transmittance Ti2 within the second infrared wavelength range (53). In some aspects, Tv / Ti2≤2.5, or Tv / Ti2≤2.25, or Tv / Ti2≤2, or Tv / Ti2≤1.75.

[0062] In some other embodiments, the normalized solar spectrum (80) may further include a third infrared wavelength range (54), which may be at least 50 nm wide and within a range of 800 nm to 2500 nm. The second infrared wavelength range (53) may be disposed between the first infrared wavelength range (52) and the third infrared wavelength range (54). In some examples, the third infrared wavelength range (54) may extend from about 1200 nm to about 1300 nm, such as Figure 4 shown.

[0063] The normalized solar spectrum (80) may have an average relative intensity Si3 within the third infrared wavelength range (54), such that 0.05≤Si3≤Si2. For the incident light, the at least one polarization state, and the first incident angle range, the integrated optical film may have an average optical transmittance Ti3 within the third infrared wavelength range (54). In some cases, Tv / Ti3≥2, or Tv / Ti3≥2.5, or Tv / Ti3≥3, or Tv / Ti3≥3.5, or Tv / Ti3≥4.

[0064] In some other embodiments, the normalized solar spectrum (80) may further include a fourth infrared wavelength range (55), which may be at least 50 nm wide and within a range of 800 nm to 2500 nm. The third infrared wavelength range (54) may be disposed between the second infrared wavelength range (53) and the fourth infrared wavelength range (55). In some examples, the fourth infrared wavelength range (55) may extend from about 1500 nm to about 1750 nm, such as Figure 4 shown.

[0065] The normalized solar spectrum (80) may have an average relative intensity Si4 within the fourth infrared wavelength range (55), such that 0.05≤Si4≤Si3. For the incident light, the at least one polarization state, and the first incident angle range, the integrated optical film may have an average optical transmittance Ti4 within the fourth infrared wavelength range (55). In some cases, Tv / Ti4≤2, or Tv / Ti4≤1.75, or Tv / Ti4≤1.5, or Tv / Ti4≤1.25, or Tv / Ti4≤1.1.

[0066] like Figure 4 As shown, the first infrared wavelength range (52), the second infrared wavelength range (53) and the third infrared wavelength range (54) are non-overlapping wavelength ranges within 800 nm to 2500 nm. Each of the first infrared wavelength range (52), the second infrared wavelength range (53) and the third infrared wavelength range (54) may have a width of at least 40 nm, or 45 nm, or 50 nm, or 55 nm, or 60 nm, or 70 nm, or 80 nm, or 90 nm, or 95 nm.

[0067] In some embodiments, the normalized solar spectrum (80) may have average relative intensities Sv, Si1, Si2, and Si3 in the corresponding visible wavelength range (50) and the first infrared wavelength to the third infrared wavelength range (52-54) such that Sv>Si1>Si2>Si3≥0.1. In some instances, Sv>Si1>Si2>Si3≥0.15. In some other instances, Sv>Si1>Si2>Si3≥0.2. In some other instances, Sv>Si1>Si2>Si3≥0.25.

[0068] In some embodiments, the integrated optical film may have average optical transmittances Tv, Ti1, Ti2, and Ti3 in the corresponding visible wavelength range (50) and the first infrared wavelength to the third infrared wavelength range (52-54), so that each of Tv / Ti1 and Tv / Ti3 may be greater than 1.4. In some examples, each of Tv / Ti1 and Tv / Ti3 may be greater than 1.5, or greater than 1.75, or greater than 2, or greater than 2.25, or greater than 2.5, or greater than 2.75, or greater than 3, or greater than 3.25, or greater than 3.5. In some other examples, Tv / Ti2≤2.5, or Tv / Ti2≤2.25, or Tv / Ti2≤2, or Tv / Ti2≤1.75.

[0069] Table 3 shows the relative intensities of the normalized solar spectrum in the visible wavelength range (420nm to 680nm), the first infrared wavelength range (700nm to 950nm), the second infrared wavelength range (1000nm to 1100nm), the third infrared wavelength range (1200nm to 1300nm) and the fourth infrared wavelength range (1500nm to 1570nm).

[0070] Table 3

[0071] Sv(420 to 680) 0.89 Si1 (700 to 950) 0.57 Si2 (1000 to 1100) 0.39 Si3 (1200 to 1300) 0.26 Si4 (1500 to 1750) 0.14 Sv / Si1 1.57 Sv / Si2 2.27 Sv / Si3 3.40 Sv / Si4 6.47

[0072] Table 4 shows the average optical transmittance of different optical film configurations (OF1, OF2...OF9) in the visible wavelength range (420nm to 680nm), the first infrared wavelength range (700nm to 950nm), the second infrared wavelength range (1000nm to 1100nm), the third infrared wavelength range (1200nm to 1300nm) and the fourth infrared wavelength range (1500nm to 1570nm), and in a first incident angle range extending from about 0° to about 85°.

[0073] Table 4

[0074]

[0075] Figure 8 The average optical transmittance of the integrated optical film according to one or more embodiments of the present disclosure is shown in combination with the sunlight intensity of the normalized solar spectrum. The exemplary embodiments show that for incident light (40, Figure 1 ) and the relationship between the optical transmittance (110) of the integrated optical film and the wavelength for at least one polarization state (x-axis and y-axis).

[0076] The optical transmittance (110) includes a first transmission band (100) and a second transmission band (102). The optical transmittance (100) further includes a first transmission stop band (101) and a second infrared transmission stop band (103). The first transmission stop band (101) is arranged between the first transmission band (100) and the second transmission band (102), and the second infrared transmission stop band (103) is arranged adjacent to the second transmission band (102) opposite to the first transmission stop band (101).

[0077] The first transmission band (100) may include at least most wavelengths in a visible wavelength range (50) extending from about 420 nm to about 680 nm. The first transmission stop band (101) may include at least most wavelengths in a first infrared wavelength range (52) extending from about 700 nm to about 950 nm. The second infrared transmission stop band (103) may include at least some wavelengths in a second infrared wavelength range (54) extending from about 1200 nm to about 1300 nm.

[0078] In some embodiments, for the visible wavelength range (50), the integrated optical film can have an average optical transmittance Tv for the first incident angle. For the second infrared wavelength range (54), the integrated optical film can have an average optical transmittance Ti for the first incident angle.

[0079] For a second incident angle greater than about 30 degrees, or 35 degrees, or 40 degrees, or 45 degrees, or 50 degrees, or 55 degrees, or 60 degrees, the integrated optical film may have average optical transmittances Tv' and Ti' for the visible wavelength range (50) and the second infrared wavelength range (54), respectively.

[0080] In some cases, Tv and Tv' may be within 30% of each other. In some other cases, Tv and Tv' may be within 25%, or 20%, or 15%, or 10% of each other.

[0081] In some cases, Ti may be at least 1.3 times greater than Ti'. In some other cases, Ti may be at least 1.4 times, or 1.5 times, or 1.6 times, or 1.7 times, or 1.8 times, or 1.9 times, or 2 times, or 2.1 times, or 2.2 times, or 2.3 times, or 2.4 times, or 2.5 times greater than Ti'.

[0082] Table 5 shows the average optical transmittance of the optical film according to one embodiment in the visible wavelength range and the infrared wavelength range at incident angles of 0° and 45°.

[0083] Table 5

[0084]

[0085] Table 6 shows different optical film designs and their corresponding transmittance at visible wavelengths (average 380nm to 780nm, normal incidence) and LiDAR operating wavelengths (average over the range of 45° to 75° at 905nm), as well as solar emission performance (weighted reflectance totaled over wavelengths of R times the intensity of sunlight).

[0086] Table 6

[0087]

[0088] Figure 7 An optical sensing system (400) is shown, which includes a windshield (300) having an integrated optical film (200) of one or more embodiments of the present disclosure, the integrated optical film being disposed between a first substrate (90) and a second substrate (91). In some cases, the first substrate (90) and the second substrate (91) may be IR transparent glass. The optical film (200) may be bonded to the first substrate (90) and the second substrate (91) via respective first bonding layers (92) and second bonding layers (93). The windshield (300) may be transparent and colorless in the visible wavelength range.

[0089] The optical sensing system (400) includes a transceiver (110) having at least one of a transmitter (111) and a receiver (112). In some cases, the transceiver (110) may include at least one transmitter (111) and at least one receiver (112). In some aspects, the transmitter (111) may include a laser light source. The receiver (112) may include an optical detector, and in some cases, the receiver (1120) may include a camera. In some embodiments, the transceiver (110) may be a LiDAR transceiver.

[0090] The transceiver (110) may be configured to transmit (120) and / or receive (121) first light that passes through the windshield (300) toward the object (130). The emitted first light may have a wavelength between about 850 nm and about 950 nm or between about 900 nm and about 950 nm. In some cases, the emitted first light may have a wavelength between about 1400 nm and about 1700 nm or between about 1500 nm and about 1600 nm. The emitted first light may include a pulsed laser or a continuous laser. In some cases, the continuous laser may be at least one of phase modulated and frequency modulated.

[0091] The transceiver (110) can be disposed in an interior cabin of a vehicle such that the integrated optical film (200) can be disposed between the transceiver (110) and an exterior surface of a windshield (300). In one aspect, the transceiver (110) can be disposed on or near an interior rearview mirror of the vehicle. For example, the transceiver (110) can be a LiDAR transceiver disposed behind the rearview mirror.

[0092] In the LiDAR spectrum, the windshield (300) may allow the first light to pass through at a designed angle range. For example, the first light may be emitted or received along the propagation direction (120a, 121a). The first light emitted or received along the propagation direction (120a, 121a) is at a first angle (α1, α2) in the air with the normal (140) of the windshield (300). In some cases, the first angle (α1, α2) may be greater than about 20 degrees, or greater than about 25 degrees, or greater than about 30 degrees, or greater than about 35 degrees, or greater than about 40 degrees, or greater than about 45 degrees, or greater than about 50 degrees, or greater than about 55 degrees, or greater than about 60 degrees, or greater than about 65 degrees. In the rest of the solar spectrum, the windshield (300) reflects or absorbs the incident light to maintain thermal comfort in the cab and the LiDAR system cabin behind the windshield (300).

[0093] Unless otherwise indicated, the description of the elements in the drawings should be understood to be equally applicable to the corresponding elements in the other drawings. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that the specific embodiments shown and described may be replaced with a variety of alternative and / or equivalent implementations without departing from the scope of the present disclosure. The present application is intended to cover any modification or variation or combination of the specific embodiments discussed herein. Therefore, the present disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An integrated optical film, the integrated optical film comprising a plurality of first optical repeating units with a total number of at least 10, the plurality of first optical repeating units being disposed on a plurality of second optical repeating units with a total number of at least 10 and separated from the plurality of second optical repeating units by at least one spacing layer, each of the first optical repeating units having at least microlayers A1 and B1 of different compositions, each of the second optical repeating units having at least microlayers A2, B2, and C2 of different compositions, at least one of the microlayers A1 and B2 having a different composition from the microlayers A2, B2, and C2 at least one different component, each of the microlayers in the first optical repeating unit and the second optical repeating unit has an average thickness of less than about 500 nm, and each of the at least one spacer layer has an average thickness of greater than about 500 nm, so that for incident light, for at least one polarization state, a visible wavelength range extending from about 420 nm to about 680 nm, an infrared wavelength range at least 10 nm wide and within 750 nm to 1000 nm, a first incident angle range extending from about 0 degrees to about 20 degrees, and a second incident angle range extending from about 45 degrees to about 75 degrees, the integrated optical film has the following conditions: For the visible wavelength range, an average optical transmittance for each of the first range of incident angles and the second range of incident angles is greater than about 45%; and For the infrared wavelength range, an average optical transmittance for the first incident angle range is less than about 20%, and an average optical transmittance for the second incident angle range is greater than about 45%, wherein the integrated optical film has an integrated construction.

2. An optical structure comprising a windshield, the windshield comprising the integrated optical film according to claim 1, the integrated optical film being disposed between a first glass substrate and a second glass substrate and bonded to the first glass substrate and the second glass substrate.

3. An optical sensing system, comprising: The windshield according to claim 2; and A transceiver comprising at least one of a transmitter and a receiver and configured to at least one of transmit and receive first light passing through the windshield toward an object along a propagation direction in air at a first angle to a normal to the windshield, the first angle being greater than about 20 degrees. 4 . The optical sensing system of claim 3 , wherein the transceiver comprises at least one transmitter and at least one receiver.

5. The optical sensing system of claim 3, wherein the transmitter comprises a laser light source and the receiver comprises an optical detector.

6. An integrated optical film comprising a plurality of at least first to third microlayers, the plurality of at least first to third microlayers having different compositions and a total number of at least 20, each of the at least first to third microlayers having an average thickness of less than about 500 nm, So that for incident light, for at least one polarization state, a first incident angle range extending from about 0 degrees to at least about 40 degrees, and an air mass of 1.5 and a normalized solar spectrum normalized on a sunlight wavelength range that includes at least a visible wavelength and a first infrared wavelength range, the normalized solar spectrum has average relative intensities Sv and Si1 in the corresponding visible wavelength range and the first infrared wavelength range, and the integrated optical film has average optical transmittances Tv and Ti1 in the corresponding visible wavelength range and the first infrared wavelength range, the visible wavelength range extends from about 420nm to about 680nm, the first infrared wavelength range is at least 50nm wide and is within 800nm ​​to 2500nm, Sv>Si1≥0.2, Tv / Ti1≥1.

4. The integrated optical film according to claim 6 , wherein 1≤Sv / Si1≤2.

8. The integrated optical film according to claim 6, wherein the normalized solar spectrum also includes a second infrared wavelength range that is at least 50 nm wide and within a range of 800 nm to 2500 nm, the first infrared wavelength range is disposed between the visible wavelength range and the second infrared wavelength range, wherein the normalized solar spectrum has an average relative intensity Si2 within the second infrared wavelength range, Si2≤Si1, so that for the incident light, the at least one polarization state and the first incident angle range, the integrated optical film has an average optical transmittance Ti2 within the second infrared wavelength range, Tv / Ti2≤2.

5.

9. The integrated optical film according to claim 8, wherein the normalized solar spectrum also includes a third infrared wavelength range that is at least 50 nm wide and within a range of 800 nm to 2500 nm, and the second infrared wavelength range is arranged between the first infrared wavelength range and the third infrared wavelength range, wherein the normalized solar spectrum has an average relative intensity Si3 within the third infrared wavelength range, 0.05≤Si3≤Si2, so that for the incident light, the at least one polarization state and the first incident angle range, the integrated optical film has an average optical transmittance Ti3 within the third infrared wavelength range, Tv / Ti3≥2.

10. The integrated optical film according to claim 9, wherein the normalized solar spectrum also includes a fourth infrared wavelength range that is at least 50 nm wide and within a range of 800 nm to 2500 nm, and the third infrared wavelength range is disposed between the second infrared wavelength range and the fourth infrared wavelength range, wherein the normalized solar spectrum has an average relative intensity Si4 within the fourth infrared wavelength range, 0.05≤Si4≤Si3, so that for the incident light, the at least one polarization state and the first incident angle range, the integrated optical film has an average optical transmittance Ti4 within the fourth infrared wavelength range, Tv / Ti4≤2.

11. An integrated optical film comprising a plurality of at least first to third microlayers, the plurality of at least first to third microlayers having different compositions and a total number of at least 20, each of the at least first to third microlayers having an average thickness of less than about 500 nm, So that for incident light, for at least one polarization state, a first incident angle range extending from about 0 degrees to at least about 40 degrees, and an air quality of 1.5 and a normalized solar spectrum normalized over a sunlight wavelength range including a visible wavelength range and at least a non-overlapping first infrared wavelength range, a second infrared wavelength range, and a third infrared wavelength range, the normalized solar spectrum and the integrated optical film have corresponding average relative intensities Sv, Si1, Si2, and Si3 in the corresponding visible wavelength range and the first infrared wavelength to the third infrared wavelength range and average optical transmittance Tv, Ti1, Ti2 and Ti3, the visible wavelength range extends from about 420nm to about 680nm, at least the non-overlapping first infrared wavelength range, the second infrared wavelength range and the third infrared wavelength range are within 800nm ​​to 2500nm, have corresponding average relative intensities Si1, Si2 and Si3 and are each at least 40nm wide, Sv>Si1>Si2>Si3≥0.1, each of Tv / Ti1 and Tv / Ti3 is greater than 1.4, and Tv / Ti2≤2.

5.

12. An integrated optical film according to claim 11, wherein the plurality of at least the first to third microlayers include a plurality of alternating microlayers A1 and B1 with a total number of at least 5 arranged on a plurality of alternating microlayers A2, C2, B2 and C2 with a total number of at least 10, the microlayers A1 and B1 have different compositions, the microlayers A2, B2 and C2 have different compositions, at least one of the microlayers A1 and B1 has a different composition from at least one of the microlayers A2, B2 and C2, and each of the microlayers A1, B1, A2, B2 and C2 has an average thickness of less than about 500 nm.

13. The integrated optical film of claim 11, wherein the plurality of at least the first to third microlayers include a plurality of alternating microlayers A1, C1, B1, and C1, numbering at least 50, disposed on a plurality of alternating microlayers A2, C2, B2, and C2, numbering at least 200, the microlayers A1, B1, and C1 having different compositions, the microlayers A2, B2, and C2 having different compositions, at least one of the microlayers A1, B1, and C1 having a composition different from at least one of the microlayers A2, B2, and C2, and each of the microlayers A1, B1, C1, A2, B2, and C2 having an average thickness of less than about 500 nm.

14. An integrated optical film according to claim 11, wherein the plurality of at least the first to third microlayers include a plurality of alternating microlayers A1 and B1 with a total number of at least 50 arranged on a plurality of alternating microlayers A2, B3, A3, B2, A3 and B3 with a total number of at least 100, the microlayers A1 and B1 having different compositions, the microlayers A2 and A3 having substantially the same composition and different thicknesses, the microlayers B2 and B3 having substantially the same composition and different thicknesses, at least one of the microlayers A1 and B1 having a different composition from at least one of the microlayers A2 and B2, and each of the microlayers A1, B1, A2, B2, A3, B3 having an average thickness of less than about 500 nm.

15. The integrated optical film of claim 14, wherein at least most of the microlayers in microlayer A1 are thinner than at least most of the microlayers in microlayer B2, and at least most of the microlayers in microlayer B1 are thicker than at least most of the microlayers in microlayers A3 and B3.

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