Optical filter with improved viewing angle characteristics

Abstract

The light absorption filter comprises a chiral anisotropic liquid crystal host having positive anisotropy and a dichroic light-absorbing portion associated with the host. The filter has an absorbance A of light measured at an incidence angle θ from the normal to the filter surface. θ However, according to Beer's Law, the absorbance A is predicted when θ is at least 30°. T It is characterized by being at least 1% higher or at least 1% lower than [the specified value]. The light absorption filter can be used in combination with optical elements and light sources.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority and other interests of U.S. Provisional Patent Application No. 63 / 451,647, “Optical Filter with Improved Viewing Angle Characteristics,” filed on 13 March 2023, the entire disclosure of which is fully incorporated herein by reference.

[0002] Technical field This disclosure relates to optical filters, and more particularly to optical filters that reduce or control vignetting characteristics. [Background technology]

[0003] Optical filters are widely used in various optical systems to control the amount of light from a light source received by the eye, a sensor, or other photosensitive element. For example, a person may wear tinted sunglasses to reduce the amount of ambient light entering their eyes. A photographer may use filters on their camera lens. Many conventional optical filters are light-absorbing filters that contain some kind of light-absorbing material (usually organic or inorganic dyes or pigments). The light-absorbing material may be dispersed in a polymer film or glass, or in a liquid or gel sandwiched between transparent plates or films. Such filters may function as neutral density filters or color filters. Some optical filters are passive filters, having a relatively fixed set of properties at the time of manufacture. Active filters are also known, which can change optical properties such as light transmittance based on some stimulus such as voltage, current, heat, or ultraviolet light. In some non-limiting examples, active optical filters can be based on electrochromic technology, liquid crystal technology, photochromic technology, etc.

[0004] The amount of light absorbed by a light-absorbing filter follows the generally well-known Beale's law: A = ∈ lC, where A = absorbance, ∈ = absorption coefficient, C = concentration of the light-absorbing material, and l = optical path length. Figure 1 is a cross-sectional view of a conventional light-absorbing filter. Light 126a, 126b, and 126c from a light source (e.g., the scene being photographed) pass through the optical filter 101 to produce attenuated light 126a', 126b', and 126c', which are received by a light sensor 140 (which may be a camera, a human eye, or other radiation-sensitive device). Light 126b is perpendicular to the surface of the optical filter, while light 126a and 126c are incident at an angle θ1 with respect to the normal. Because the refractive index of the light-absorbing filter is higher than that of air (e.g., the refractive index of glass is 1.52, compared to approximately 1 for air), the light in the filter passes through at an angle θ2 according to Snell's law. The optical path lengths of light 126a and 126c passing through the filter (optical path lengths 130a and 130c, respectively) are longer than the optical path length of light 126b (optical path length 130b). As the optical path length increases, the absorption of light 126a and 126c becomes greater than the absorption of light 126b. For the optical sensor 140, the scene appears darker at the edges of the optical filter compared to the center. This phenomenon causes "aperture vignetting." There are many other optical effects that can contribute to aperture vignetting, and Beale's Law is just one of them. While aperture vignetting is acceptable in many applications, it can be undesirable in situations where a high field of view is used or required, such as with wide-angle lenses or panoramic images.

[0005] Therefore, there is a need for optical filters that can attenuate light while reducing vignetting. [Overview of the project]

[0006] According to some embodiments, the light absorption filter is arranged in relation to an optical element and a light source. The light absorption filter includes a chiral anisotropic liquid crystal host having positive anisotropy and a dichroic light-absorbing portion associated with the host. The filter has an absorbance A of light measured at an angle θ of incidence from the normal to the filter surface. θHowever, according to Beer's Law, the absorbance A is predicted when θ is at least 30°. T It is characterized by being at least 1% higher or at least 1% lower than [the specified value]. The light absorption filter can be used in combination with optical elements and light sources.

[0007] According to another embodiment, the light-absorbing filter includes a chiral anisotropic liquid crystal host having a dichroic light-absorbing portion in combination with the host, and the filter is characterized by formula (1).

number

[0008] (Here, in equation (1), OM = aperture ecliptic metric (OM is in the range of -1.3 to 3.0), D(λ) = dichromatic ratio of the light-absorbing portion at wavelength λ, |△n| = birefringence of the liquid crystal host, p = pitch of the liquid crystal host (μm), and λ = wavelength of light absorbed by light-absorbing water (μm))

[0009] This disclosure may provide an optical absorption filter having at least one or more of the following advantages compared to conventional optical absorption filters: reduced vignetting, controllable or adjustable vignetting, more uniform appearance at angles other than perpendicular to the filter, better field-of-view performance, or improved compatibility with wide-angle lenses. In some cases, the optical absorption filter of the present invention may be used in conjunction with a camera lens system for capturing vignetting-reduced optically filtered images. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a conventional optical filter. [Figure 2A] 2A (camera image) and 2B (graph) show the vignetting performance of a conventional optical filter in combination with a wide-angle lens as a function of angle. [Figure 2B]2A (camera image) and 2B (graph) show the vignetting performance of a conventional optical filter in combination with a wide-angle lens as a function of angle. [Figure 3A] 3A (camera image) and 3B (graph) show the vignetting performance of an example of an optical filter combined with a wide-angle lens as a function of angle. [Figure 3B] 3A (camera image) and 3B (graph) show the vignetting performance of an example of an optical filter combined with a wide-angle lens as a function of angle. [Figure 4] This is a cross-sectional view of a non-limiting example of an active optical filter according to several embodiments. [Modes for carrying out the invention]

[0011] It should be understood that the embodiments include various aspects, which can be combined in various ways. The following description is provided to enumerate the elements of the present invention and to illustrate several embodiments. These elements are described in the first embodiment, but it should be understood that they can be combined in any way and in any number to create additional embodiments. The various examples and embodiments described should not be construed as limiting the embodiments of this application to only the systems, technologies, and uses explicitly described. It should be understood that the drawings are intended to illustrate the concepts of this disclosure and may not be to scale.

[0012] The terms "approximately" and "about" can be used to include any numerical value that can change without altering the fundamental function of that value. When used with a range, "approximately" and "about" also disclose a range defined by the absolute values ​​of the two endpoints; for example, "approximately 2 to approximately 4" also discloses the range "2 to 4".

[0013] In this specification, phrases describing a range of values ​​include the final value; for example, "between X and Y," "range from X to Y," and "from X to Y" include both X and Y, and "up to Y" includes Y.

[0014] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and their variations as used herein and in the claims, are intended to be unrestrictive transitional phrases, terms, or words that require the presence of a specified component, component, or step, and permit the presence of other components, components, or steps.

[0015] This disclosure may include one or more of the following terms, whose meanings are as set forth below. definition

[0016] As used herein, “absorption” may define the proportion of light absorbed by a guest-host mixture, cell, optical device, etc.

[0017] The "absorption band" can be defined as the spectral wavelength at which absorption occurs.

[0018] As used herein, "clear state" or "clear state transmittance" may refer to the state in which an active optical filter exhibits maximum or relatively high light transmittance.

[0019] "Dark state" or "dark state transmittance" may refer to the state in which an active optical filter exhibits minimum or relatively low light transmittance.

[0020] "Dichroic (DC) dyes" are rod-shaped and have a molecular structure parallel to the α / / ) and vertical (α ⊥ This dye molecule exhibits unique anisotropy in its light absorption properties, and this is due to the dichromatic ratio, DR=α / / / α ⊥ It is characterized by the following: Molecules whose dichroism ratio (DR) is outside the range of 1 are molecules that exhibit "dichroism".

[0021] "Dichroic ratio", "average dichroic ratio", D(λ)>, or D of a mixture mixrefers to the dichroic ratio of a guest-host mixture that may contain one or more DC dyes. D(λ) is the dichroic ratio measured at wavelength λ, and is usually in the visible light region of 400-700 nm. The mixed dichroic ratio can be measured using the formula for the effective dichroic ratio (D eff ) or the total effective dichroic ratio (D eff-agg ). Therefore, D(λ), D mix , D eff or D eff-agg used herein are used interchangeably (depending on which method is used to measure the dichroic ratio) and represent the same parameter.

[0022] As used herein, "narrow-band absorption" is defined as having a full width at half maximum (FWHM) of the spectral absorption band of 175 nm or less, or 165 nm, 155 nm, 120 nm, or 80 nm or less, and the entire spectral absorption band is measured within the visible region of 400-700 nm.

[0023] A "narrow-band mixture" refers to a guest-host liquid crystal mixture that can be used in a narrow-band cell. The nematic-isotropic transition temperature or T NI is the temperature at which the liquid crystal undergoes a transition from the nematic to the isotropic state. This is a transition from the nematic phase with orientational order to the completely disordered isotropic phase. In this specification, T NI refers to the nematic-isotropic transition temperature of the guest-host mixture.

[0024] The "order parameter of the guest-host mixture" or "S mix " refers to the order parameter of the guest-host mixture. The mixture may contain one or more dyes and other dopants. S mix can be measured according to the methods described herein. For example, it can be measured using the formula for the effective order parameter (S eff [[ID=3​​​​​​​These are used interchangeably (depending on the method used to measure the order parameter) and represent the same parameter.

[0025] "Polarization dependence" is a measure of a material's response to two orthogonal linearly polarized beams; in other words, the optical properties of a material (such as refractive index and absorption / transmittance) that it receives from incident light depend on the polarization of the incident light.

[0026] "Polarization sensitivity" is a relative measure of the difference in a material's response to first- and second-orthogonal-polarized incident light. In the ideal theoretical limit, a polarization sensitivity of 0% refers to a device that is completely independent of polarization, while 100% refers to a device that is completely sensitive to polarization obtained using a polarizer.

[0027] A "polarizer" refers to a material, layer, or component that absorbs or reflects more of one polarity of incident light than of a polarity perpendicular to it.

[0028] "Transmittance" and "transmittance" are used interchangeably and refer to the proportion of light that passes through a mixture or device.

[0029] "Transmittance fluctuation" refers to the difference in transmittance between the transparent state and the dark state. For example, if the transmittance in the transparent state is 65% and the transmittance in the dark state is 15%, the transmittance fluctuation is 65-15=40%. The transmittance fluctuation of optical instruments can be measured using instruments such as BYK-Gardner's "haze-gard plus" or equivalent instruments.

[0030] "Uniform optical retardation" refers to a plastic substrate in which the variation in optical retardation across the entire substrate is less than ±20% at any given wavelength. "Optical retardation" is defined as a change in optical phase caused by different polarizations of incident light.

[0031] "Visible light" refers to the wavelength range of approximately 400 to 700 nm.

[0032] As used herein, “broadband absorption” refers to a spectral absorption band beyond 175 nm, preferably beyond 180 nm, 185 nm, 190 nm, 195 nm, or 200 nm, where the entire spectral absorption band is typically within the visible wavelength range assumed to be 400 nm to 700 nm, and broadband absorption may have color, although it may sometimes have low chromaticity.

[0033] "Broadband mixture" refers to a guest-host liquid crystal mixture that can be used in broadband cells.

[0034] The inventors have conducted extensive research, particularly in the field of variable transmittance optical devices using liquid crystal guest-host (LC-GH) technology. Such technology has achieved commercial success in numerous applications, such as electronically controlled variable transmittance goggles and windows. A large range of transmittance is often a valued performance indicator in such applications. It has been found that higher transmittance can be achieved by designing LC-GH systems to have relatively low polarization dependence. For example, material sets with low birefringence or material sets that do not operate within the Morgan limit have been preferred. In this case, the system exhibits aperture vignetting similar to that expected in conventional absorption systems. However, it has been found that redesigning the LC-GH system, as described in this application, provides an optical filter that exhibits remarkably reduced aperture vignetting while still maintaining effective light attenuation characteristics. The optical filter of this application may be either active or passive, as described below. Initial Test

[0035] To test vignetting, the optical filter in question was placed on a light table designed to illuminate uniformly in all directions. A camera fitted with a fisheye lens was placed directly on the filter, and images were captured. The relative light intensity received was plotted as a function of the angle from the normal. comparison

[0036] A commercially available light-absorbing glass neutral density filter (ThorLabs product number NE210B) was tested and found to have a rated optical density of 1.0, allowing for 10% transmittance of incident light perpendicular to the filter (θ1=0°). Figure 2A is the camera image itself, and Figure 2B is a graph showing the relative intensity (in arbitrary units) as a function of angle from the normal, measured along line 202 superimposed on Figure 2A. At a normal incident angle (0°), the transmitted light intensity count is approximately 215. At an incident angle of 60° in either direction, the transmitted light intensity count drops to approximately 120, a decrease of about 44%. Even at an incident angle of 40°, the transmitted light count drops to approximately 175, a decrease of about 19%. Thus, while aperture vignetting is quite significant, the performance is in close agreement with what would be predicted by Beale's Law (combined with Snell's Law). example

[0037] A passive LC-GH system was prepared using a set of dichroic dyes in a chiral liquid crystal host within a planar oriented cell. The dichroic ratio of the dichroic dyes in the LC host was approximately 15. The liquid crystal host was positively anisotropic, with a birefringence of approximately 0.12 and a pitch of approximately 4 microns. The LC-GH material was placed between two transparent substrates, and the combination of dyes generally produced a neutral density filter. Absolute %T or absorbance was not measured, but it was clearly darker than the reference filter. The example filter was tested in a similar manner to the reference filter. Figure 3A is the camera image itself, and Figure 3B is a graph showing the relative intensity (in arbitrary units, not necessarily on the same scale as Figure 2B in an absolute sense) as a function of angle from the normal, roughly measured along line 302 superimposed on Figure 3A. At a normal incident angle (0°), the transmitted light intensity count is approximately 155. At an incident angle of 60°, the transmitted light intensity count drops to approximately 120, a decrease of only 23%. At a 40° incidence, the transmitted light count is 145-140, a decrease of only 6-10%. The curve in Figure 3B is clearly flatter than the curve in Figure 2B. The "x" marks in Figure 3B indicate the expected intensity if the filter were to operate similarly to the conventional comparative filter in Figures 2A / 2B. The optical filter in this example not only exhibits less vignetting than the comparative filter, but also does not sacrifice light attenuation performance. In fact, the illustrated optical filter is both a more powerful (higher light absorption) filter and a filter with less vignetting.

[0038] The example filters described above are merely illustrations. In some cases, instead of adding small-molecule dichroic guests that match the LC host material, dichroic light-absorbing moieties covalently bonded to the LC host material may be included. In some cases, instead of using a fluid LC-GH mixture between two substrates, the LC-GH material itself may be a self-supporting polymer film. A vignetting reduction optical filter, rather than a neutral density filter, may be designed to filter specific colors. For convenience, the following sections concerning LC-GH materials and properties are provided primarily in the context of active optical filters, but a skilled technician will understand how the teachings of the present invention can generally be applied to passive optical filters. In the case of active optical filters, most of the discussion concerns systems with reduced vignetting. However, in some embodiments, active optical filters may be designed to have variable vignetting. Greater vignetting may be desirable for artistic effects or to reduce interference at high viewing angles. Active optical filters can be designed to switch between different levels of vignetting, such as reduced vignetting and increased vignetting (dynamic or variable vignetting optical filters).

[0039] Figure 4 is a cross-sectional view of a non-limiting example of an active optical filter according to several embodiments. The incident light 26 is at least partially absorbed by the optical filter 10 and passes through as transmitted (attenuated) light 27. Although only one filter is shown in the figure, the incident light may pass through two or more filters.

[0040] The optical filter 10 may include a pair of substrates 12a, 12b. As will be detailed later, the substrates may be independently selected and may include, for example, polymer materials, glass, or ceramics. A pair of transparent conductive layers, 14a, 14b, may be provided on or coated onto the surface of each substrate inside the cell. In some embodiments, optional passivation layers (which may optionally be called insulating layers or “hard coats”) 16a, 16b may be provided on each transparent conductive layer. The passivation layers may include, for example, nonconductive oxides, sol gels, polymers, or composite materials. Optionally, orientation layers 18a, 18b may be provided on the passivation layers or transparent conductive layers. As a non-limiting example, the orientation layers may include polyimide. In some embodiments, the orientation layers may function as passivation layers. In some embodiments, the orientation layers may be rubbed to help orient an electro-optic material near the surface, such as an LC host, as is known in the art. In some embodiments, both orientation layers of the cell are rubbed. In some embodiments, the cell may contain only one brushed orientation layer.

[0041] The optical filter 10 includes an electro-optic material 25 provided between substrates. In the case of an active optical filter, the electro-optic material can change from a state of low light transmittance to a state of high light transmittance in a first wavelength region in response to a change in the electric field applied to the electro-optic material. The electric field can be changed, for example, by changing the voltage applied between a pair of transparent conductive layers 14a, 14b. In some embodiments, the electro-optic material is an LC-GH material. As shown in Figure 4, in some embodiments, the LC-GH material may be in a state of highest light absorption (dark state) when no voltage is applied. In some cases, using an LC host with positive anisotropy can provide an eclipse-reducing optical filter that has a dark state at V=0. Conversely, an LC host with negative anisotropy can be used to produce an optical filter that is relatively clear (high transmittance) at V=0, but when a voltage is applied to create a dark state, it can produce an optical filter with relatively little eclipse. In such cases, applying an intermediate voltage causes eclipse to occur between what is observed in the clear state and the dark state. In some cases, dynamic or variable aperture ecliptic filters may have a multilayer structure including a first cell having a positively anisotropic LC host and a second cell having a negatively anisotropic LC host.

[0042] The substrate and the layers thereon define the cell gap 20 ("d"). In some embodiments (not shown), the cell may include spacer beads or other structures to maintain the gap. In some cases, the cell structure may be surrounded by a sealing material 13, such as a UV-curing optical adhesive or other sealants known in the art.

[0043] The conductive layer can be electrically connected to a variable voltage source schematically indicated by V1 enclosed in a circle. Figure 4 shows the cell power supply circuit with switch 28 open and no voltage applied, and the optical filter in the dark state. When switch 28 is closed, a variable voltage or electric field can be applied to the liquid crystal guest host material 25. Electro-optical materials

[0044] Electro-optic materials are materials whose light absorption profile can be altered by applying an electric field. In some embodiments, electro-optic materials may include a guest host system having an LC host and a DC dye dissolved or dispersed therein, or alternatively, a dichroic light-absorbing moiety covalently bonded to the LC host (all considered guest host mixtures). Whether in the form of dissolution, dispersion, or attachment, such compositions may be called LC-GH materials or mixtures.

[0045] In some embodiments, the liquid crystal guest host comprises a mixture of a cholesteric or chiral nematic liquid crystal host and a dye material. The dye material may be characterized by dichroic properties and may contain a single dye or a mixture of dyes (DC light absorbing moiety) to provide these properties, as described later. In some embodiments, the liquid crystal guest host mixture may be formulated as a “narrowband mixture” for producing a color filter, or as a “broadband mixture” for producing a generally neutral density filter. In the context of guest host materials, the term “mixture” is generally used broadly herein and may refer to a DC moiety covalently bonded to the LC host. The guest host mixture does not necessarily have to be a simple combination of individual dye molecules and liquid crystal molecules. LC host

[0046] In some embodiments, the host includes a chiral nematic or cholesteric liquid crystal material (collectively, "CLC") which may have negative dielectric anisotropy ("negative CLC") or positive dielectric anisotropy ("positive CLC"). In some cases, positive CLC may be selected to reduce aperture vignetting. In other cases, negative CLC may be selected to increase aperture vignetting. In some embodiments of CLC, the liquid crystal material is cholesteric or includes a nematic liquid crystal in combination with a chiral dopant. The CLC material has a twisted structure, i.e., a helical structure. The periodicity of the twist is called "pitch" ("p"). The orientation or order of the liquid crystal host may be altered by the application of an electric field and may be used in combination with a dye material to control or partially control the optical properties of an optical filter. In some embodiments, CLC may be further characterized by its chirality, i.e., right-handed chirality or left-handed chirality. Order parameter and dichromatic ratio

[0047] The maximum contrast between the clear and dark states of an active LC cell depends on the orientation of the dichroic dye. Dichroic dyes have the ability to orient with nematic liquid crystal molecules when mixed. When an electric field is applied to such a guest-host mixture, the nematic liquid crystal host molecules reorient and align themselves to be either perpendicular to or aligned with the electric field in order to minimize the torque they experience from the field. While dichroic dye (guest) molecules may not be directly affected by the external electric field, they can still align with the liquid crystal host molecules. Interaction with the liquid crystal molecules compels them to reorient.

[0048] The statistically averaged orientation of elongated molecules, consisting of liquid crystal molecules and dichroic dyes, in a guest-host mixture points to a specific direction called the "director." Because all molecules in the mixture undergo random thermal motion during diffusion, even when an electric field is applied, each molecule will not be oriented in exactly the same direction as its orientation vector. The statistical average of molecular orientation is the average angle θ of the molecules relative to the orientation vector. avgThis indicates that the molecules are tilted. This molecular tilt is characterized by a convenient quantity called the "order parameter S''", which can also be calculated. The range of this value is 0 to 1. The order parameter S = 1 is the state in which all molecules are perfectly aligned with the director (θ''). avg This corresponds to =0°. (See Liquid Crystals Applications and Uses, vol.3, edited by B. Bahadur, published by World Scientific Publishing Co. Pte. Ltd., 1992). Therefore, the higher the order parameter S, the more aligned the dichroic dye molecules are, and the more optimized the absorption at a particular molecular orientation. This invention relates to the effective order parameter S mix The mixture contains a dichroic dye liquid crystal guest host mixture in which the ratio is 0.78, 0.79, or 0.8 or higher.

[0049] In this specification, "guest-host mixture order parameter value" or "S mix " refers to the order parameter of the guest-host mixture. The mixture may contain one or more dyes and other dopants. mix For example, S eff or S eff-agg It can be measured using the formula. Therefore, the S used here mix S eff , and S eff-agg These are used interchangeably (depending on the method used to measure the order parameter) and represent the same parameter. "Dye order parameter value" or "S 染料 This refers to the order parameter of the transition dipole of each dichroic dye relative to the director.

[0050] In one example, the effective ordering parameter of a guest host mixture containing one or more dichroic dyes is S eff =(D eff -1) / (D eff It is calculated as +2), where D eff =( ∫A || (λ)dλ) / (∫A⊥ (λ)dλ) is the "effective dichromatic ratio", A || (λ) and A ⊥ (λ) is the parallel and perpendicular absorbance of the dye, and D(λ) is the corresponding dichromatic ratio at wavelength λ. Typically, ∫A || (λ)dλ and ∫A ⊥ (λ)dλ is typically evaluated over the absorption wavelength region within the 380–780 nm range of the spectrum. In this invention, these integrals can be evaluated over the FWHM of the absorption spectrum of a broadband dichroic dye mixture, or over a specific wavelength, such as the 400–700 nm range of the spectrum. If the absorption spectrum has a single peak, the integral can be evaluated simply, and the integration limit is the wavelength at the endpoint of the full width at half maximum of the spectrum. If the absorption spectrum has multiple distinct peaks, the integral is evaluated piecewise, and the integration limit is the wavelength at the endpoint of the full width at half maximum of each peak. This piecewise integral allows the applicant to determine the "total dichroism" D eff-agg and the "total effective order parameter" S eff-agg Something called this is generated.

[0051] The order parameter of a mixture can be determined by optically measuring the light transmittance in the stationary and energized states using linearly polarized and / or circularly polarized light at multiple wavelengths inside and outside the absorption spectrum. Then, the order parameter can be determined by numerical fitting to experimental data using liquid crystal optics simulation techniques developed by Berreman (Berreman DW 1972, Optics in Stratified and Anisotropic Media: 4×4-Matrix Formulation. Journal of the Optical Society of America, 62(4), 502) or Odano (Allia, P., Oldano, G., & Trossi, L., 1986, 4×4 Matrix approach to chiral liquid-crystal optics. Journal of the Optical Society of America B, 3(3), 424). These simulation methods are used by those skilled in the art or through commercially available programs such as Twisted Cell Optics by Kelly (Kelly, J., Jamal, S., & Cui, M., 1999, Simulation of the dynamics of twisted nematic devices including flow. Journal of Applied Physics, 86(8), 4091).

[0052] In this invention, an order parameter of 1 also indicates that all molecules are aligned with one another. For example, all dichroic dye molecules are aligned with one another, exhibiting nearly identical absorption cross-sections for incident light and maximizing absorption in a particular direction. Of course, it should be kept in mind that achieving perfect orientation is difficult because molecules are always affected by thermal motion. To maximize optical performance, a guest-host mixture is desired in which the intermolecular orientation is enhanced by the application of an external electric field.

[0053] In some examples, the desired guest-host mixture is one with an order parameter value S. mix It is greater than 0.78. In other examples, S mix It is 0.79 or higher. In other examples, S mix It is 0.8 or higher. To provide a wide range of transmittance (30-70%, preferably over 35%) across the entire A-FWHM, S mix A mixture with a ratio of >0.78 is required.

[0054] In some cases, when using multiple dyes, it is desirable that all dyes have nearly the same order parameter to minimize color changes in the resting (non-electric) and electrically energized states. Similarly, the "dichroism ratio," "average dichroism ratio," or D of a mixture mix This refers to the dichroism ratio of a guest-host mixture across the entire spectral region, which may contain one or more dichroic dyes. As explained above, the dichroism ratio is D eff Or D eff-agg It can be measured using the formula. Therefore, D(λ), D used herein mix , D eff Or D eff-agg These are used interchangeably (depending on the method used to measure the dichromatic ratio) and represent the same parameter.

[0055] Dye materials

[0056] To impart dichroic properties, the dye material typically contains at least one dichroic (DC) dye or a mixture of DC dyes (a DC light-absorbing portion). In some cases, the dye material may further optionally contain a photochromic (PC) dye or a photochromic dichroic (PCDC) dye whose light absorption is activated by exposure to ultraviolet light, such as sunlight. In some embodiments, the dye material may further contain small amounts of conventional absorbent dyes, for example, to provide the device with the desired overall hue in a transparent state. In some embodiments, the dye material contains substantially only DC dyes.

[0057] dc dye

[0058] Dichroic dyes typically have an elongated molecular shape and exhibit anisotropic absorption. Generally, absorption is high along the long axis of the molecule, and such dyes may be called “positive dyes” or dyes exhibiting positive dichroism. Positive DC dyes are commonly used here. However, in some cases, negative DC dyes exhibiting negative dichroism may be used instead. In some embodiments, DC dyes (measured on a CLC host) may have a dichroism ratio of at least 5.0, or at least 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. In some cases, the dichroism ratio of DC dyes (measured on a CLC host) may be in the range of 5–6, 6–8, 8–10, 10–15, 15–20, 20–25, 25–30, or any combination of these ranges. 。

[0059] The level of visible light absorption by a DC dye can be a function of the type of dye and the CLC host. In the case of the active optical filters of this disclosure, the apparent absorption of visible light can also be a function of voltage. The orientation or long-range order of the CLC can be a function of the electric field or voltage across the entire thickness of the cell. Since the DC dye exhibits some degree of orientation with the CLC host, the apparent darkness of the cell can be altered by applying a voltage.

[0060] In some embodiments, DC dyes may comprise small molecule type materials (organic, inorganic, organometallic, metal-organic complexes, etc.). In some embodiments, DC dyes may comprise oligomer or polymer materials. The chemical site involved in light absorption may be, for example, a pendant group on the main chain. Multiple DC dyes may optionally be used, for example, to adjust the light absorption envelope or to improve overall cell performance in terms of lifetime or other properties. DC dyes may comprise functional groups that improve solubility, miscibility, or binding to the CLC host. Non-limiting examples of DC dyes include azo dyes, e.g., azo dyes having 2 to 10 azo groups, or 2 to 6 azo groups. Other DC dyes, such as anthraquinone dyes and perylene dyes, are also known in the art. Generally, any molecule exhibiting dichroism can be used.

[0061] In some embodiments, the guest-host mixture has a nematic-isotropic transition temperature (TNI) greater than 40°C. In other embodiments, the TNI is greater than 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C.

[0062] In some embodiments, the optical filter has an order parameter S mix The mixture includes a guest-host mixture in which the ratio is 0.60, 0.65, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, or 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, or 0.85 or greater.

[0063] In some embodiments, the wide-angle, vignetting-reducing optical filters of the present disclosure may use a guest-host mixture which can be described as “chiral planar”. Other cell characteristics substrate

[0064] Referring again to Figure 4, in some embodiments, substrates 12a and 12b are independently selected and may include plastic, glass, ceramic, or other materials. The choice of material and its properties will vary to some extent depending on the application. The substrate must transmit visible light at least partially. In some embodiments, the substrate may have a transmittance of more than 45% for visible light having wavelengths of 400 nm to 700 nm, or it may have a transmittance of more than 50%, 60%, 70%, 80%, 90%, or 95%. In some embodiments, the substrate has high optical transparency, so that a person or sensor can be clearly seen through the optical filter 10. In some embodiments, the substrate may optionally have some color or tint. In some embodiments, the substrate may have an optical coating on the outside of the cell. The substrate may be flexible or rigid.

[0065] In some non-limiting examples, plastic substrates may include polycarbonate (PC), blends of polycarbonate and copolymers, polyethersulfone (PES), polyethylene terephthalate (PET), cellulose triacetate (TAC), polyamide, p-nitrophenyl butyrate (PNB), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), polyetherimide (PEI), polyarylate (PAR), polyvinyl acetate, cyclic olefin polymers (COP), or other similar plastics known in the art. In some non-limiting examples, flexible glass, including materials such as Corning® Willow® Glass, may be used as a substrate. The substrate may contain multiple materials or have a multilayer structure. In some embodiments, the optical filter may use a plastic substrate having an optical delay with uniformity variation of less than ±20%, less than ±15%, or less than ±10% across the entire area of ​​the device.

[0066] In some embodiments, the substrate thickness may be in the range of 10-20 μm, 20-30 μm, 30-40 μm, 40-50 μm, 50-75 μm, 75-100 μm, 100-150 μm, 150-200 μm, 200-250 μm, 250-300 μm, 300-350 μm, 350-400 μm, 400-450 μm, 450-500 μm, 500-600 μm, 600-800 μm, 800-1000 μm, or greater than 1 mm, or any combination of these ranges.

[0067] Transparent conductive layer

[0068] A “transparent” conductive layer means that conductive layers 14a and 14b transmit at least 45% of incident visible light. A transparent conductive layer is still useful even if it absorbs or reflects some of the visible light. In some embodiments, the transparent conductive layer may include, but is not limited to, a transparent conductive oxide (TCO) containing ITO or AZO. In some embodiments, the transparent conductive layer may include, but is not limited to, a conductive polymer containing PEDOT:PSS, polypyrrole, polyaniline, polyphenylene, or polyacetylene. In some embodiments, the transparent conductive layer may include a partially transparent thin layer of metal or metal nanowires, for example, formed of silver, copper, aluminum, or gold. In some embodiments, the transparent conductive layer may include graphene. Characteristics of optical filter systems

[0069] As mentioned earlier, many variable transmittance optical filters are designed to maximize the range of transmittance. One approach is to minimize polarization dependence. Furthermore, ideally, the propagation eigenmodes are independent of the propagation angle. This can be most effectively achieved, for example, by lowering the birefringence. However, in the case of vignetting reduction optical filters, it has been found that a redesign of the system is necessary. In some cases, the angular dependence of the propagation eigenmodes can be utilized to counteract the additional losses seen in isotropic materials as predicted by Beale's law. For example, in vignetting reduction optical filters, a material with high birefringence can be used to achieve operation close to the Morgan limit.

[0070] As is well known in the art, the refractive index of a birefringent material depends on the polarization of light. In some cases, a birefringent material may be characterized by △n. This value can be positive or negative, but unless otherwise specified, △n as used herein refers to its absolute value. In some embodiments, an LC host may have |△n| at least 0.04, or at least 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. In some cases, an LC host may have |△n| less than or equal to 0.3, or less than or equal to 0.2. In some embodiments, an LC host may have |△n| in the range of 0.04 to 0.06, 0.06 to 0.08, 0.08 to 0.10, 0.10 to 0.15, 0.15 to 0.20, 0.20 to 0.25, 0.25 to 0.30, or any combination of these ranges. In some embodiments, an LC host may be characterized by positive anisotropy.

[0071] In some embodiments, the LC-GH material layer pitch p may be at least the same size as the wavelength of light absorbed by the DC portion. In some embodiments, p is at least 300 nm, or at least 400 nm, 500 nm, 750 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or 10 μm. In some embodiments, p is in the range of 400-500 nm, 500-750 nm, 750 nm-1 μm, 1-2 μm, 2-3 μm, 3-4 μm, 4-5 μm, 5-10 μm, 10-15 μm, 15-20 μm, 20-25 μm, 25-30 μm, or any combination of these ranges.

[0072] In some embodiments, the thickness of the optical filter cell gap or LC-GH material layer may be in the range of 3-5 μm, 5-7 μm, 7-10 μm, 10-15 μm, or 15-20 μm, 20-25 μm, 25-30 μm, 30-40 μm, 40-50 μm, 50-70 μm, 70-100 μm, or any combination of these ranges, or may exceed 100 μm.

[0073] In some embodiments, the optical filter may be characterized by a d / p ratio, where "d" refers to the thickness of the LC-GH material layer and "p" refers to the pitch of the torsion LC host. In embodiments where low aperture erosion is desired, the d / p ratio may be at least 0.1, or at least 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some embodiments, the d / p ratio is in the range of 0.1 to 0.5, or in the range of 0.5 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, 9 to 10, 10 to 15, 15 to 20, or any combination of these ranges.

[0074] In some embodiments, the vignetting reduction optical filter may use an LC host having positive anisotropy with |△n| in the range of 0.04 to 0.20, p in the range of 0.8 to 4 microns, a d / p ratio in the range of 0.25 to 4, and an order parameter of 0.6 to 0.9.

[0075] In some cases, the physical and optical properties of an optical filter may be characterized by an ecliptic metric (OM) represented by equation (1).

number

[0076] In some embodiments, the average clear state transmittance of the active optical filter in the wavelength range of 400 nm to 700 nm may be 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or more. In some embodiments, the average dark state transmittance of the active optical filter in the wavelength range of 400 nm to 700 nm may be 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or 1% or less. In some embodiments, the active optical filter may have a transmittance swing (the difference between the highest transmittance "clear" state and the lowest transmittance "dark" state) of 30% or more, or greater than 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. The aforementioned transmittance levels may, in some cases, apply to the entire wavelength range of 400 nm to 700 nm, but may also apply to only a single wavelength within this range, or to a subset of wavelengths within this range. In some cases, any of the aforementioned transmittance levels may correspond to the wavelength ranges of 400-420nm, 420-440nm, 440-460nm, 460-480nm, 480-500nm, 500-520nm, 520-540nm, 540-560nm, 560-580nm, 580-600nm, 600-620nm, 620-640nm, 640-660nm, 660-680nm, or 680-700nm, or any combination of these ranges.

[0077] In some embodiments, the optical filters (active or passive) of the Disclosure may have an absorbance of at least 0.05 for perpendicularly incident light (θ1=0°), or at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0, 2.5, or 3.0. In some embodiments, the optical filters may have an absorbance of 0.05–0.2, 0.2–0.3, 0.3–0.4, 0.4–0.5, 0.5–0.7, 0.7–1.0, 1.0–1.5, 1.5–2.0, 2.0–2.5, 2.5–3.0, or any combination of these ranges. Such absorption levels relate to the wavelength or wavelength range in question.

[0078] In some embodiments, the optical filters of the present disclosure may feature an absorbance (or %T) that deviates from the absorbance (or %T) predicted by Beale's law for light incident at an angle θ1 from the normal, where θ1 is greater than 0°, for example, 10°, 20°, 30°, 40°, 50°, or 60°. "Predicted by Beale's law" refers to the predicted absorbance after applying Snell's law, which takes into account the path length through the filter and reflection losses at the air / filter interface, based on the filter's average refractive index and the angle of incidence. In some embodiments, this deviation is observed when θ1 is in the range of 10° to 20°, or 20° to 30°, 30° to 40°, 40° to 50°, 50° to 60°, 60° to 70°, or any combination of these ranges. In some embodiments, the test of such deviation from Beale's Law can be performed at any angle within the above range, e.g., 20°, 30°, 40°, 45°, 50°, or 60°. In some embodiments, the filter may have or produce an absorbance of at least 0.1, or at least 0.2, 0.5, 1.0, or 2.0, with respect to normal incident light (θ1=0°). In some embodiments, the filter may have or produce a %T of less than about 80%, or about 70%, 60%, 50%, 20%, 10%, 5%, or less than 1%, with respect to normal incident light (θ1=0°).

[0079] In the case of vignetting reduction optical filters, the absorbance may be lower than that predicted by Beil's law for θ1 > 0°. For example, the absorbance measured at one or more of the aforementioned θ1 angles or ranges may be less than 0.99 times the absorbance predicted by Beil's law ("absorbance deviation coefficient"), or less than 0.98, 0.97, 0.95, 0.93, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, or 0.60 times the absorbance predicted by Beil's law. In some embodiments, the absorption deviation coefficient of the vignetting reduction optical filter may decrease as θ1 increases.

[0080] Similarly, in the case of vignetting reduction optical filters, %T can be higher than the value predicted by Beale's Law. For example, %T measured at one or more of the aforementioned θ1 angles or ranges may exceed 1.01 times the %T predicted by Beale's Law ("%T deviation coefficient"), or it may exceed 1.02 times, 1.05 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.7 times, 2.0 times, 2.5 times, or 3 times the %T predicted by Beale's Law.

[0081] As described above, some of the optical filters of this disclosure may be designed to increase (or vary between increase and decrease) vignetting. In the case of vignetting-increasing optical filters, the absorbance may be higher than θ1 > 0° as predicted by Beale's law. For example, the absorbance measured at one or more of the aforementioned θ1 angles or ranges may be more than 1.01 times the absorbance predicted by Beale's law ("absorbance deviation coefficient"), or more than 1.02, 1.03, 1.05, 1.07, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, or 1.40 times the absorbance predicted by Beale's law. In some embodiments, the higher θ1, the higher the absorbance deviation coefficient of the vignetting-increasing optical filter may be.

[0082] Similarly, in the case of vignetting optical filters, %T can be higher than predicted by Beale's Law. For example, the %T measured at one or more of the aforementioned θ1 angles or ranges may be less than 0.99 times the %T predicted by Beale's Law ("%T deviation coefficient"), or it may be less than 0.98, 0.95, 0.90, 0.8, 0.7, 0.6, 0.5, 0.3, or 0.1 times the %T predicted by Beale's Law.

[0083] A variable aperture vignetting filter (usually an active filter) is a filter that can produce different levels of vignetting when measured within a range, for example, 30° to 70°, while the absorbance or %T measured perpendicular to the filter remains the same. In some embodiments, the variable aperture vignetting filter can alternate between reducing and increasing vignetting.

[0084] In some embodiments, the optical filter of the present disclosure measures the absorbance A of light measured at an incident angle θ1 from the normal to the filter surface. θ This is characterized by the theoretical absorbance A predicted by Beer's Law when θ is in the range of 30° to 70°. T The absorbance is at least 1% higher or at least 1% lower than the absorbance (A) measured perpendicular to the filter. N ) is at least 0.1, or at least 0.5 or at least 1.0. In some cases, A θ is 0.99A T ~1.01A T Outside the range, or 0.98A T ~1.02A T、 0.95A T ~1.05A T , 0.93A T ~1.07A T , or 0.90A T ~1.10A TThis may be outside the range. In some embodiments, the variable aperture vignetting filter may be designed to operate within the described range in addition to operating outside the described range (up and / or down). For aperture vignetting reduction optical filters, A θ is 1.01A T It can be larger, or 1.02A T , 1.05A T , 1.07A T , or 1.10A T It can be larger. In the case of a vignetting filter, A θ is 0.99A T It may be less than 0.98A T , 0.95A T , 0.93A T , or 0.90A T It may be less than.

[0085] In some embodiments, the optical filter measures the absorbance (A) of the incident light perpendicular to the filter. N ) and the absorbance (A) at an angle θ from the normal. θ It is characterized by a diameter erosion coefficient VF corresponding to the ratio of ). That is, VF = A N / A θ In some embodiments, the optical filter of the present disclosure has a θ = 40° (i.e., V 40 When measured at 0.89-0.93, the filter may have or produce a VF outside the range of 0.89-0.93, 0.88-0.94, or 0.87-0.95, and the filter may have an absorbance (A) measured perpendicular to the filter. NThe VF is at least 0.1, or at least 0.5, or at least 1.0. In some embodiments, variable vignetting filters may be designed to operate within the described range in addition to operating outside the described range (above and / or below). For vignetting reduction optical filters (also measured at θ=40°), the VF may be greater than 0.93, or greater than 0.94, or greater than 0.95. In some embodiments, the VF of a vignetting reduction optical filter is 1.0 or less. In some cases, the VF of an optical filter may even be greater than 1.0, which is also called reverse vignetting. For vignetting increase optical filters (measured at θ=40°), the VF may be less than 0.89, or less than 0.88, or less than 0.87. The VF may in some cases be a function of the angle of incidence. For example, the absorbance (A) measured perpendicular to the filter when measured at θ=60°. N If θ is at least 0.1, or at least 0.5 or at least 1.0, the optical filters of this disclosure may have or produce a VF outside the ranges of 0.79–0.84, 0.78–0.85, 0.77–0.86, 0.75–0.88, or 0.73–0.90. In some embodiments, variable vignetting filters may be designed to operate within the described ranges in addition to operating outside (above and / or below) the described ranges. For vignetting reduction optical filters (also measured at θ=60°), the VF may be greater than 0.84, or greater than 0.85, 0.86, 0.88, or 0.90. For vignetting increase optical filters (measured at θ=60°), the VF may be less than 0.79, or less than 0.78, 0.77, 0.75, or 0.73.

[0086] Purpose

[0087] In some embodiments, the aperture vignetting reduction optical filter (passive or active, particularly passive) of the present disclosure can be used in a camera system. In some cases, such a camera system can employ a wide-angle lens, and this filter can be called a wide-angle optical filter. Such a camera system can use either a digital imaging sensor (such as CMOS, CCD, etc.) or silver halide film. Useful camera systems include still cameras, video cameras, movie cameras, and the like.

[0088] In some embodiments, the active aperture vignetting reduction optical filter of the present disclosure is particularly suitable for vehicle sunroofs or other window applications where uniform darkness is important and, in some cases, performance in the clear state is equally or more important.

[0089] In some embodiments, a variable aperture vignetting active optical filter can be used to create a desired edge darkening effect in a camera system, sunroof, window, or glasses. <OO00443> Further embodiments of the present specification include the embodiments listed below. 1. An optical absorption filter disposed in relation to an optical element and a light source, the filter comprising a chiral anisotropic liquid crystal host and a dichroic light absorption portion associated with the host, and an absorbance A of light measured at an incident angle θ from the normal to the filter surface θ is at least 1% higher or at least 1% lower than the absorbance A predicted by Beer's law when θ is at least 30°. T Characterized by. 2. The optical absorption filter of embodiment 1, for at least one incident angle θ within the range of 30° to 70°, the A θ is outside the range of 0.99A T to 1.01A T Range. 3. The optical absorption filter of embodiment 2, the A θ is outside the range of 0.98 A T to 1.02A T Range, or optionally 0.95AT ~1.05A T , 0.93A T ~1.07A T , or 0.90A T ~1.10A T It is outside the scope. 4. A light absorption filter according to any one of Embodiments 1 to 3, wherein θ is about 40° or about 60°. 5. A light absorption filter according to any one of Embodiments 1 to 4, wherein the filter is 1.01A T Larger A θ It has, or optionally 1.02A T , 1.05A T , 1.07A T , or 1.10A T Larger A θ This is a grooving reduction filter that has the following properties. 6. A light absorption filter according to any one of Embodiments 1 to 4, wherein the filter is A θ 0.99A T Less than, or arbitrarily 0.98A T , 0.95A T , 0.93A T , or 0.90A T This is a vignetting filter that is less than [a certain value]. 7. A light absorption filter according to any one of Embodiments 1 to 6, wherein the filter is a passive filter. 8. A light absorption filter according to any one of Embodiments 1 to 7, wherein the filter is an active filter. 9. A light absorption filter according to any one of Embodiments 1 to 4, wherein the filter is an active variable aperture erosion filter. 10. A light-absorbing filter according to any one of Embodiments 1 to 9, wherein the absorbance of the filter is at least 0.1, or optionally at least 0.2, 0.5, or 1.0, with respect to light incident perpendicular to the filter. 11. A light-absorbing filter arranged in relation to an optical element and a light source, wherein the filter includes a chiral anisotropic liquid crystal host and a dichroic light-absorbing portion associated with the host, Here, a) VF θ =A N / A θ Here, i) VF θ ii) A N iii) A θ This is the absorbance of light incident at an angle θ, b) A N It is 0.1 or greater, and also, c) When θ = 40°, VF 40 This value is outside the range of 0.89 to 0.93. 12. A light absorption filter according to Embodiment 11, wherein the VF 40 This refers to a value outside the range of 0.88 to 0.94, or any value outside the range of 0.87 to 0.95. 13. A light absorption filter of embodiment 11 or 12, wherein when θ = 60°, VF 60 This is outside the range of 0.79 to 0.84, or arbitrarily outside the ranges of 0.78 to 0.85, 0.77 to 0.86, 0.75 to 0.88, or 0.73 to 0.90. 14. A light absorption filter according to any one of embodiments 11 to 13, wherein A N is at least 0.2, or optionally at least 0.5, or 1.0. 15. A light absorption filter according to any one of embodiments 11 to 14, wherein the filter has a VF greater than 0.93, or optionally greater than 0.94 or 0.95. 40 This is a grooving reduction filter that has [specific properties]. 16. A light absorption filter according to any one of embodiments 11 to 14, wherein the VF 40 This is a vignetting filter whose value is less than 0.89, or arbitrarily less than 0.88 or 0.87. 17. A light absorption filter according to any one of embodiments 11 to 16, wherein the filter is a passive filter. 18. A light-absorbing filter according to any one of embodiments 11 to 17, wherein the filter is an active filter. 19. A light absorption filter according to any one of embodiments 11 to 14, wherein the filter is an active variable aperture erosion filter. 20. A light-absorbing filter according to any one of Embodiments 1 to 19, wherein the optical element is a lens. 21. The light absorption filter of Embodiment 20, wherein the lens is a wide-angle lens. 22. An optical absorption filter according to any one of Embodiments 1 to 19, wherein the optical element is a sensor of an imaging device. 23. A light absorption filter according to any one of Embodiments 1 to 22, wherein the light source corresponds to the ambient environment for image capture by a camera. 24. A light-absorbing filter according to any one of Embodiments 1 to 19, wherein the optical element includes a sunroof or a window. 25. A light-absorbing filter according to any one of Embodiments 1 to 24, wherein the light-absorbing portion comprises one or more dichroic dyes. 26. A light-absorbing filter according to Embodiment 25, wherein the one or more dichroic dyes are combined with a liquid crystal host as a mixture. 27. A light-absorbing filter according to embodiment 25 or 26, wherein the at least one dichroic dye is covalently bonded to a liquid crystal host. 28. A light-absorbing filter according to any one of embodiments 25 to 27, wherein the liquid crystal host is a polymer. 29. A light-absorbing filter according to any one of Embodiments 1 to 28, wherein the dichromatic ratio of the light-absorbing portion is at least 5. 30. A light-absorbing filter according to any one of Embodiments 1 to 29, wherein the anisotropic liquid crystal host and the dichroic light-absorbing portion are provided between two substrates. 31. A light-absorbing filter according to any one of Embodiments 1 to 29, wherein the filter is in the form of a self-supporting polymer film including an anisotropic liquid crystal host and a dichroic light-absorbing portion. 32. A light-absorbing filter according to any one of Embodiments 1 to 31, wherein the filter is a neutral density filter having an absorbance of at least 0.5. 33. A light absorption filter according to any one of Embodiments 1 to 32, wherein the filter is a color filter having an absorbance of at least 0.5 for at least one wavelength in the range of 400 nm to 700 nm. 34. A light-absorbing filter according to any one of embodiments 1 to 33, wherein the filter is substantially planar. 35. A light-absorbing filter according to any one of Embodiments 1 to 33, wherein the filter includes a multi-curved surface. 36. A light absorption filter according to any one of Embodiments 1 to 35, wherein the filter is laminated on an optical element. 37. A light absorption filter according to any one of embodiments 1 to 36, wherein the liquid crystal host has positive anisotropy. 38. A light absorption filter according to any one of Embodiments 1 to 37, wherein the birefringence |△n| of the liquid crystal host is at least 0.04, or optionally in the range of 0.04 to 0.30, or optionally in the range of 0.06 to 0.20, or optionally in the range of 0.06 to 0.17. 39. A light-absorbing filter according to any one of Embodiments 1 to 38, wherein the dichromatic ratio D of the light-absorbing portion is in the range of 5 to 30, or arbitrarily in the range of 8 to 20. 40. A light absorption filter according to any one of Embodiments 1 to 39, characterized in that the pitch p of the liquid crystal host is in the range of 0.3 to 30 μm, or arbitrarily in the range of 1 to 15 μm, or arbitrarily in the range of 4 to 12 μm. 41. A light-absorbing filter according to any one of Embodiments 1 to 40, wherein the filter is further characterized by formula (1).

number

number

[0091] The specific details of particular embodiments can be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present invention. However, other embodiments of the present invention may be directed to specific embodiments relating to each individual aspect, or to specific combinations of these individual aspects.

[0092] The above description of exemplary embodiments of the present invention is provided for illustrative and explanatory purposes only. It is not exhaustive and is not limited to the exact forms described herein, and many modifications and changes are possible in light of the above teachings.

[0093] The above description includes numerous details to facilitate understanding of various embodiments of the technology for illustrative purposes. However, it will be apparent to those skilled in the art that certain embodiments can be implemented by omitting some of these details or by adding additional details.

[0094] While several embodiments have been described, it will be understood by those skilled in the art that various modifications, alternative configurations, and equivalents can be used without departing from the spirit of the invention. Furthermore, to avoid unnecessarily obscuring the invention, many well-known processes and elements have been omitted from description. Moreover, details of a particular embodiment are not necessarily present in variations of that embodiment and may be added to other embodiments.

[0095] Where a range of values ​​is indicated, the upper and lower limits are also included within that range. Furthermore, unless the context clearly indicates otherwise, it is understood that each intermediate value between the upper and lower limits of that range (up to one-tenth of the lower limit) is also specifically disclosed. Each smaller range between any specified value or intermediate value within the given range and any other specified value or intermediate value within that given range is covered. The upper and lower limits of these smaller ranges may be independently included in or excluded from the range, and each range in which either, either, or both limits are included within the smaller range is also included in the invention, according to the limits specifically excluded within the described range. Where the described range includes one or both limit values, ranges excluding either or both of the included limit values ​​are also included.

[0096] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include multiple references unless the context clearly indicates otherwise. For example, a reference to “method” includes multiple such methods, and a reference to “layer” includes one or more layers and their equivalents known to those skilled in the art. The present invention has been described in detail for clarity and understanding. However, it can be understood that certain changes and modifications are possible within the scope of the appended claims.

[0097] All publications, patents, and patent applications cited herein are incorporated herein by reference in their entirety for all purposes and none are considered prior art.

Claims

1. A light-absorbing filter arranged in relation to an optical element and a light source, wherein the filter includes a chiral anisotropic liquid crystal host having positive anisotropy and a dichroic light-absorbing portion associated with the host, Absorbance A of light, measured at the angle θ of incidence from the normal to the filter surface. θ However, according to Beer's Law, the absorbance A is predicted when θ is at least 30°. Ｔ A light-absorbing filter characterized by being at least 1% higher or at least 1% lower than [a certain value].

2. The light-absorbing filter according to claim 1, wherein the birefringence |△n| of the liquid crystal host is in the range of 0.06 to 0.

20.

3. The light-absorbing filter according to claim 1, wherein the dichromatic ratio D of the light-absorbing portion is at least 5.

4. The light-absorbing filter according to claim 3, wherein D is in the range of 8 to 20.

5. The light-absorbing filter according to claim 1, wherein the pitch of the liquid crystal host is in the range of 1 to 15 μm.

6. The light-absorbing filter according to claim 1, wherein the filter is further characterized by formula (1). [Math 1] (Here, OM = Vinetting Optical Index (where OM is in the range of -1.3 to 3.0) D(λ) = Dichromatic ratio of the light-absorbing region at wavelength λ |△n| = Birefringence of liquid crystal host p = pitch of the liquid crystal host (μm), and, λ = wavelength of light absorbed by the light-absorbing region (μm)

7. The light-absorbing filter according to claim 6, wherein the OM is in the range of 0.3 to 2.

0.

8. For at least one incident angle θ within the range of 30° to 70°, A θ 0.99A Ｔ ~1.01A Ｔ The light-absorbing filter according to claim 1, which is outside the range.

9. The aforementioned filter is 1.02A Ｔ Larger A θ The light absorption filter according to claim 1, which is a vignetting reduction filter having the following properties.

10. The light absorption filter according to claim 1, wherein the filter is a passive filter or an active variable aperture filter.

11. The light-absorbing filter according to claim 1, wherein the absorbance of the filter is at least 0.1 for light incident perpendicularly to the filter.

12. A light-absorbing filter arranged in relation to an optical element and a light source, wherein the filter includes a chiral anisotropic liquid crystal host having a dichroic light-absorbing portion in relation to the host, and the filter is characterized by formula (1). [Math 2] (Here, OM = Vinetting Optical Index (where OM is in the range of -1.3 to 3.0) D(λ) = Dichromatic ratio of the light-absorbing region at wavelength λ |△n| = Birefringence of liquid crystal host p = pitch of the liquid crystal host (μm), and λ = wavelength of light absorbed by the light-absorbing region (μm)

13. The light-absorbing filter according to claim 12, wherein the OM is in the range of 0.3 to 2.

0.

14. The light-absorbing filter according to claim 12, wherein |△n| is in the range of 0.06 to 0.

20.

15. The light-absorbing filter according to claim 12, wherein D is in the range of 8 to 20.

16. The light-absorbing filter according to claim 12, wherein the p is in the range of 1 to 15 μm.

17. The light-absorbing filter according to claim 12, wherein the absorbance at λ is at least 0.5 for light incident perpendicularly to the filter.

18. The light-absorbing filter according to claim 12, wherein the filter is a passive filter or an active variable aperture filter.

19. The light-absorbing filter according to claim 12, wherein the optical element is a lens or sensor of an image sensor, and the light source corresponds to the surrounding environment for image capture by a camera.

20. The light-absorbing filter according to claim 12, wherein the optical element includes a sunroof or window.

21. The light-absorbing filter according to claim 12, wherein the liquid crystal host has positive or negative anisotropy.

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