UV wavelength selective filters

Abstract

The present invention is an ultraviolet wavelength selective filter. The wavelength selective filter includes a filter material. The filter material includes a main matrix doped with metal ions. The filter material has a transmission region within the deep ultraviolet (UV) range, so that UV light with a wavelength within the transmission region is transmitted through the filter material.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is related to and claims the benefit of U.S. Provisional Application No. 63 / 043,089, filed on June 23, 2020, and entitled “Ultraviolet Light Wavelength Selective FILTER,” which is incorporated herein by reference in its entirety. Technical Field

[0003]

[0014] Embodiments of the present disclosure relate generally to filtering light emitted by a light source, and particularly to filtering ultraviolet (UV) light. Background Art

[0004] Many UV light sources emit light of various wavelengths in at least one relatively wide wavelength band. Some wavelengths are desirable, such as for disinfecting the air and / or surfaces in an enclosed space, while other emission wavelengths are not desirable due to interference with disinfection or for other reasons. In order to provide an effective disinfection method utilizing these UV light sources, the ultraviolet light should be filtered to absorb any undesirable wavelengths and transmit the light of the desired wavelength required to kill bacteria and viruses. The desired wavelength can be in the deep UV region of the electromagnetic spectrum, which refers to the region from 190 nanometers (nm) to 280nm in this article. Most known filters are designed for wavelengths above 300nm and therefore cannot selectively transmit the desired wavelength in the deep UV region for disinfection.

[0005] One type of filter designed for the deep UV region is called an interference filter and is based on a multilayer stack of dielectric materials and metals that produces a periodic modulation of the refractive index, resulting in reflection and transmission within certain wavelength ranges in the deep UV. Interference filters have several disadvantages. For example, interference filters are complex and difficult to construct. The materials are deposited in precise amounts at high temperatures and low pressures to achieve the precise periodic modulation of the refractive index. It is well known that interference filters have relatively low transmittance in the bandpass region, which defines the wavelengths allowed to pass through the filter, and are highly dependent on the angle of incidence of the light incident on the filter. The low transmittance in the bandpass region and the high dependence on the angle of incidence are undesirable properties because they reduce the amount or rate of the desired UV light emitted from the light source, limiting the disinfection efficacy or energy of the UV light per unit time. Summary of the Invention

[0006] There is a need for a UV wavelength filter for deep UV light that provides selective filtering to achieve a narrow transmission (or bandpass) region, high transmission in the transmission region with limited or no dependence on the angle of the incident light, and is less complex and / or less expensive to manufacture than known filters, such as the interference filters described above. The UV wavelength filter should be selectively designed so that the narrow transmission region includes one or more desired wavelengths and excludes undesirable wavelengths. The desired wavelengths may be wavelengths relevant for disinfection by killing or neutralizing bacteria and viruses.

[0007] In view of these needs, certain embodiments of the present disclosure provide a wavelength selective filter comprising a filter material. The filter material comprises a matrix doped with metal ions. The filter material has a transmission region within a deep ultraviolet (UV) wavelength range, such that UV light of wavelengths within the transmission region is transmitted through the filter material.

[0008] In one or more embodiments, a method for selectively filtering ultraviolet (UV) light is provided. The method includes doping a host matrix with metal ions to form a filter material having a transmission region in the deep UV range between about 190 nm and about 280 nm. The metal ions are dispersed in the host matrix. The method includes mounting the filter material on the light source in a light propagation path of light emitted by the light source. The method also includes filtering light in the light propagation path via the filter material such that a first portion of light having a wavelength within the transmission region is transmitted through the filter material, and a second portion of light having a wavelength outside the transmission region is not transmitted through the filter material.

[0009] In one or more embodiments, a light source is provided that includes a housing, a light generating source held by the housing, and a wavelength selective filter. The light generating source is configured to emit ultraviolet (UV) light. The wavelength selective filter is disposed in a light propagation path of the UV light emitted by the light generating source. The wavelength selective filter includes a filter material having a main matrix doped with metal ions. The filter material has a transmission region within a deep ultraviolet (UV) wavelength range. A portion of the UV light emitted by the light generating source having a wavelength within the transmission region is transmitted through the wavelength selective filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A UV light source including a wavelength selective filter according to an embodiment is shown.

[0011] Figure 2 is a diagram showing how a wavelength selective filter modifies the output of a first broadband light source.

[0012] Figure 3 is a diagram showing how a wavelength selective filter modifies the output of a second broadband light source.

[0013] Figure 4 Filter materials of a wavelength selective filter according to an embodiment are shown.

[0014] Figure 5 is a diagram showing that two metal ions having respective different absorption spectra can be combined within a filter material to achieve regions of high absorption and regions of low absorption.

[0015] Figure 6 A graph showing the absorption spectrum of a first filter material is depicted.

[0016] Figure 7 A graph showing the absorption spectrum of the second filter material is depicted.

[0017] Figure 8 is a flow chart of a method for selectively filtering UV light according to an embodiment. DETAILED DESCRIPTION

[0018] When read in conjunction with the accompanying drawings, the foregoing overview and the following detailed description of certain embodiments will be better understood. As used herein, references to elements or steps in the singular and preceded by the word "a" or "an" should be understood as not necessarily excluding multiple elements or steps. Further, reference to "one embodiment" is not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the features. In addition, unless expressly stated otherwise, embodiments that "comprising" or "having" one or more elements having a particular condition may include additional elements that do not have that condition.

[0019] Embodiments of the present disclosure provide a wavelength selective filter for UV light. The wavelength selective filter is designed to allow light of a selected narrow wavelength range in the deep UV region of the electromagnetic spectrum (e.g., about 190 nm to about 280 nm) to pass through the filter with high transmittance, while absorbing other wavelengths with high optical density so that other wavelengths cannot pass through the filter. In particular, embodiments of the wavelength selective filter can be used to convert a broadband (deep) UV light source into a narrowband deep UV light source. Many deep UV light sources produce light of multiple wavelengths throughout the deep UV. For some applications, it is desirable that the deep UV light source emits only within a narrow wavelength range. One such application is the use of UV light for sterilization and disinfection in interior cabins of vehicles (such as airplanes) or buildings (such as hospitals, theaters, commercial enterprises, etc.). The wavelength selective filter can be designed to achieve high transmittance of wavelengths with antibacterial and antiviral effects without harming human tissue.

[0020] The wavelength selective filter can be used as a bandpass filter (which absorbs (or blocks) light of wavelengths above and below the transmission region - referred to as the bandpass region), a bandstop filter (which only absorbs light of wavelengths within the transmission region - referred to as the bandstop region), a shortpass filter (which only absorbs light of wavelengths above the transmission region) or a longpass filter (which only absorbs light of wavelengths below the transmission region). The term transmission region broadly refers to the wavelength range of light that is allowed to pass through the wavelength selective filter according to the embodiments described herein. Depending on the composition of the filter, the filter can be designed as a bandpass filter, a bandstop filter, a shortpass filter or a longpass filter. References herein to terms such as bandpass region and / or passband region refer only to the transmission region and are not intended to limit the application of the wavelength selective filter to being used only as a bandpass filter.

[0021] A wavelength-selective filter according to embodiments herein comprises a filter material comprising a metal ion dopant dispersed within a transparent host matrix. The host matrix is ​​a solid in some embodiments and a liquid in others. The metal ion dopant has a distinguishable intrinsic absorption band in the deep UV region and defines at least one transmission or bandpass region in which the metal ion does not absorb light. The bandpass region is influenced by the characteristics of the metal ion dopant present and the composition of the host matrix. For example, by selecting different metal ions or combinations of metal ions and / or by selecting different compositions of the host matrix, the bandpass region can be tuned during the production of the wavelength-selective filter.

[0022] One or more technical effects of the wavelength-selective filters described herein are that the filters are capable of selectively transmitting a narrow band of wavelengths in the deep UV region while blocking other wavelengths. Consequently, the wavelength-selective filters can be coupled to a broadband UV light source to enable the broadband UV source to operate as a narrowband light source. Furthermore, the wavelength-selective filters can be tuned so that the narrowband wavelengths include desired wavelengths, such as those associated with sterilization and disinfection of air and surfaces, without harming human tissue, and exclude undesirable wavelengths. The wavelength-selective filters also desirably provide high transmittance of light in the bandpass region, which can improve disinfection efficiency relative to filters that allow fewer disinfecting wavelengths to pass. The filter material can reduce or limit luminescence and may have very limited sensitivity, if any, to the angle of incident light, so that the angle of incidence of the light does not affect the intensity or amount of light transmitted through the filter. For these reasons, the wavelength-selective filters described herein can outperform other known UV filtering devices. Another technical effect is that the production of the wavelength-selective filters can be simpler and less costly than other known UV filtering devices. Furthermore, during production, the optical density of the absorption region in a wavelength-selective filter can be tuned by varying the concentration of the metal ion dopant and / or changing the thickness of the filter material without significantly affecting the transmittance of the bandpass region. In contrast, to modify the optical density in an interference filter, additional layers must be added to the filter, which inevitably reduces the transmittance of the bandpass region.

[0023] Figure 1A UV light source 100 or lamp according to an embodiment is shown. The UV light source 100 includes a light generating source 102, a housing 104, and a wavelength selective filter 106. The source 102 is disposed within a cavity 108, which is defined by the housing 104 and may also be partially defined by the filter 106. The cavity 108 can be filled with a gas. The housing 104 can be reflective along its inner surface 110. The source 102 can be a light bulb, an LED, etc. that generates and emits UV light. The filter 106 is placed in the light propagation path from the source 102 so that the UV light from the source 102 directly or indirectly (via reflection) impinges on the inner surface 112 of the filter 106. The wavelength selective filter 106 allows light 114 within a narrow wavelength transmission range (e.g., a bandpass region) to transmit through the filter 106 and exit the outer surface 116 of the filter 106 into the surrounding environment. In one embodiment, filter 106 is a bandpass filter that absorbs light rays 118 having wavelengths outside of a narrow wavelength transmission region, preventing those light rays 118 from passing through outer surface 116 into the surrounding environment. Wavelength-selective filter 106 is designed to allow light of a selected narrow wavelength range in the deep UV region (e.g., light 114) to pass through filter 106 with high transmittance, while absorbing light of other wavelengths (e.g., light 118) having high optical density, preventing the absorbed light from passing through filter 106. Filter 106 is configured to be transparent to light in a selected wavelength range (e.g., bandpass region). As used herein, the term transparent refers to at least 60% of the light or light beam averaged over the selected wavelength transmission region being transmitted through filter 106. For example, the transmittance of light having wavelengths within the transmission region may be less than 100% but greater than 60%, such as approximately 70%, 80%, or 90%.

[0024] The specific application of the wavelength selective filter 106 is to convert a deep UV broadband light source into a narrowband light source. For example, the light source 100 can be a broadband deep UV light source whose output power is centered on a wavelength, and the output light is widely distributed around the central wavelength. The width of the peak is usually described by its full width at half maximum (FWHM). The FWHM of the broadband light source in this example is greater than or equal to 5nm. The light source 100 can represent or include an excimer lamp, such as KrCl or KrBr, a mercury vapor lamp, a deuterium lamp, a xenon lamp, a mercury-xenon lamp, a UVLED or a UV laser (which uses phosphors to downshift the emission and output light in the deep UV region), an LED with an emission FWHM of 5nm or greater, etc. Installing a wavelength selective filter 106 on the light source 100 in the propagation path of the emitted broadband light converts the light source 100 into a narrowband light source. The light leaving the filter 106 essentially becomes narrowband.

[0025] The effect of our filters on such light sources is as follows Figure 2 Figure 2 shows how a wavelength selective filter changes the output of the first broadband light source. Figure 2 A first graph 120 depicting an unfiltered emission spectrum 121 of a broadband deep UV light source, a second graph 122 depicting a transmission spectrum 123 provided by a wavelength selective filter 106 according to an embodiment, and a third graph 124 depicting a resulting output spectrum 125 when the filter 106 is applied to the propagation path of the broadband deep UV light source are shown. The resulting output spectrum 125 shows a relatively narrow bandpass region 126 extending from approximately 222 nm to approximately 245 nm, which indicates narrowband deep UV light transmission. Figure 1 The light source 100 shown in FIG. 1 may emit UV light in a spectrum 125 shown in a third graph 124 .

[0026] In another example, light source 100 may represent another type of broadband light source, where the unfiltered output light is distributed in multiple peaks centered at different wavelengths. Figure 3 is a diagram showing how a wavelength selective filter modifies the output of a second broadband light source. Figure 3 It shows how a wavelength selective filter 106 can be placed in the propagation path of such a broadband light source to convert the output light into a narrowband. For example, Figure 3 A first graph 130 depicting the unfiltered emission spectrum 131 of a broadband deep UV light source is shown, along with a second graph depicting the transmission spectrum 123 provided by the wavelength selective filter 106. Figure 2 , and a third graph 134 depicting an output spectrum 135 obtained when filter 106 is applied to the propagation path of a broadband deep UV light source. Output spectrum 135 has a narrow bandpass region 136 extending from about 228 nm to about 242 nm, which represents narrowband deep UV light transmission.

[0027] Return Reference Figure 1 The wavelength selective filter 106 includes a filter material 140. The filter material 140 is disposed between the inner surface 112 and the outer surface 116 of the wavelength selective filter 106 and is a material that selectively filters incident light. Figure 4 A filter material 140 according to one embodiment is shown. The filter material 140 comprises a host matrix 142 doped with metal ions 144, in particular metal cations. The host matrix 142 is transparent. The metal ions 144 (also referred to as metal ion dopants) are dispersed throughout the host matrix 142.

[0028] The metal ion 144 may be used as a primary filter. The metal ion 144 may have a valence electron configuration of (n-1)d 10 ns 2 , where n represents the principal quantum number of the valence shell of the ion, (n-1)d 10 represents 10 electrons occupying d orbitals with principal quantum number n-1, ns2 = s represents two electrons occupying an s orbital with a quantum number of n. The metal ions 144 absorb light within a specific, intrinsic absorption range based on the elemental composition. The specific metal ions 144 present in the filter material 140 can be selected based on the absorption range to control the absorption and bandpass region of the filter 106. Non-limiting examples of metal ions 144 can include indium (Indium + ), thallium (Tl + ), tin (Sn 2+ ), lead (Pb 2+ ) and / or bismuth (Bi 3+ ). The filter material 140 may include only a single element for the primary filter (eg, In + ) or multiple different elements (e.g., In + and Sn 2+ These ions are able to absorb light in certain regions of the deep UV while being transparent (non-absorbing) in other regions.

[0029] Figure 5 Graphs showing how two metal ions with different absorption spectra can be combined within a filter material to achieve regions of high and low absorption. A first graph 150 depicts an absorption spectrum 151 of a first metal ion (e.g., metal ion "A"), a second graph 152 depicts an absorption spectrum 153 of a second metal ion (e.g., metal ion "B"), and a third graph 154 depicts a combined absorption spectrum 155. Combined absorption spectrum 155 defines a passband region 156 formed by the absorption ranges of the two metal ions.

[0030] In one embodiment, Figure 5 The two metal ions shown in FIG are combined in the same main matrix 142 ( Figure 4 ). In an alternative embodiment, the wavelength selective filter 106 can be defined by multiple layers of different filter materials in a stack such that the light propagation path travels through the stack. The first layer can include the first metal ions characterized in the first graph 150 (but not the second metal ions characterized in the second graph 152) dispersed within the host matrix. The second layer can include the second metal ions characterized in the second graph 152 (but not the first metal ions) dispersed within the host matrix. As described herein, the host material also affects the absorbance and transmittance of the filter 106. Therefore, a single type of metal ion and a combination of multiple types will result in high transparency regions and low transparency regions in the deep UV, enabling the formation and tuning of the wavelength selective filter 106. Absorbance (A) and transmittance (T) are related by the equation A=2-log(T), which is the operating principle of the wavelength selective filter 106.

[0031] For example, the "A" layer can be composed of a KBr host matrix and In+ The "B" layer can be composed of Sn 2+ and Tl + The main matrix is ​​composed of a CaCl2 matrix containing metal ions. The main matrix of each layer can be the same or different. Layers A and B can be stacked directly together, or with some deep UV transparent material between them, to produce the desired filtering properties. The number of layers can be two, three, or four, etc.

[0032] The main matrix 142 is solid in one or more embodiments and liquid in other embodiments. The main matrix 142 is transparent in the portion of the deep UV region in which the filter 106 is designed to operate, that is, it must be transparent at least in the bandpass region(s) of the filter 106. In embodiments in which the main matrix 142 is solid, the main matrix 142 can include a variety of materials.

[0033] In a first solid body embodiment, the main matrix 142 comprises an ionic salt containing a halogen anion and an alkali metal or alkaline earth metal cation. The halogen anion can be fluorine, chlorine, bromine and / or iodine. The alkali metal can be lithium, sodium, potassium, rubidium and / or cesium. The alkaline earth metal can be beryllium, magnesium, calcium, strontium and / or barium. The filter material 140 according to a first non-limiting example is doped with indium (In + The filter material 140 according to the second non-limiting example includes a first layer having a NaI matrix doped with thallium metal ions and a second layer having a KBr matrix doped with tin (Sn) metal ions.

[0034] In a second solid body embodiment, the main matrix 142 comprises a metal oxide. The metal may be silicon, providing a silica main material. For example, the silica material may be fused silica, quartz, or fused silica. In other examples, the metal may be aluminum, hafnium, and / or zirconium.

[0035] In a third solid body embodiment, the host matrix 142 comprises a non-metallic oxide salt. The non-metallic element may be boron, and the host matrix 142 may be a glass formed from borax, i.e., Na2[B4O5(OH)4]·8H2O. In another example, the non-metallic element may be phosphorus, and the host matrix 142 may be a glass formed from NaH2PO4.

[0036] In a fourth solid body embodiment, the host matrix 142 comprises a metal fluoride, wherein the metal is aluminum, lanthanum, or yttrium. In yet another embodiment, the host matrix 142 comprises a metal nitride, such as aluminum nitride or AlGaN.

[0037] The metal ions 144 can be incorporated into the solid host matrix 142 in various ways during the production of the wavelength-specific filter 106. In various embodiments, the metal ions are initially prepared as salts having halogen anions. This salt is referred to as a halide salt of a filter. The halogen anions can be fluorine, chlorine, bromine, or iodine. In a first halide salt embodiment, the solid host matrix is ​​heated to above the melting temperature of the host matrix material and the metal ions are incorporated into the molten host matrix. For example, the halide salt of the filter is added in powder form to a container containing the host matrix material in bulk or powdered form. The container is heated to or above the melting temperature of the host matrix material, causing the metal ions acting as the filter to be dispersed throughout the host matrix. The mixture is cooled, resulting in the formation of a glassy or crystalline solid composed primarily of the host matrix material, but which also contains metal ions (one or more), which are the filter agents dispersed throughout the matrix. The size and shape of the container and the amount of material present therein will determine the size of the filter material produced.

[0038] In a second halide salt embodiment, the solid main matrix is ​​not heated to a temperature higher than the melting point. On the contrary, when the main matrix is ​​lower than its melting point, the metal ions (one or more) serving as the primary filter can diffuse into the main matrix. The halide salt of the filter is added to a container containing the main matrix material in bulk or powder form in powder form. At a temperature lower than the melting point of the main matrix material, the mixture is heated for an extended period of time so that the metal ions serving as the primary filter diffuse into the main matrix. If the main matrix is ​​in bulk form, the final shape of the material does not change substantially after this process. If the main matrix is ​​in powder form, the material will remain in powder form after this process. The powder form can then be mechanically pressed into the desired shape and size.

[0039] In a third halide salt embodiment, the halide salt of the filtering agent is co-deposited with the host matrix material in a chemical or physical vapor deposition process.

[0040] Other embodiments may forgo the preparation of the halide salt of the filter.In one such embodiment, the metal ion of the primary filter is initially prepared in its elemental form and then co-deposited with the host matrix material in a chemical or physical vapor deposition process.

[0041] Alternatively, a covering material may be applied to at least a portion of the filter material. The covering material may be UV grade silicon dioxide or another stable material that is transparent in the deep UV region. The covering material may be applied to the filter material to completely encapsulate the filter material, for example, if the filter material is hygroscopic or degrades under ambient conditions (such as an alkali metal halide host matrix), or is a liquid. Another example of a possible covering material is a water-stable metal fluoride, such as MgF2.

[0042] In various other embodiments, the host matrix 142 may be a liquid solution. Suitable liquid host matrices for the WSF 106 include water, acetonitrile, cyclohexane, diethyl ether, 1,4-dimethoxybenzyl alcohol, and 1,4-dimethoxybenzyl alcohol. In one embodiment, the liquid host matrix can be contained in a container formed by a kind of solid host matrix, and this solid host matrix also has metal ion (one or more), and other filtering layer is provided.For example, metal ion can be present in the transparent container of liquid host matrix and liquid host matrix. Optionally, as mentioned above, the first subset of the metal ion of one or more types can be present in the liquid host matrix, and the second subset of the metal ion of one or more different types can be present in the solid host container.

[0043] In various embodiments, the liquid host is water. Metal ions can be incorporated by dissolving them in the form of salts in water. The metal ions represent cations, and the anions can be halides, perchlorates, or other compounds. Optionally, the oxidation state of the metal ions can be stabilized by acid or base additives added to the solution. Additionally, or alternatively, an electric potential can be applied to the solution to stabilize the oxidation state of the metal ions. The absorption region of the metal ion(s) can be altered by incorporating another anion into the solution in the form of a salt. It is also possible that a neutral compound (such as 18-crown-6 or ammonia) can act as a ligand for the metal ion, thereby changing the absorption wavelength. The properties of the additive anion shift the absorption region of the metal ion toward shorter or longer wavelengths. This makes the wavelength selective filter 106 in the liquid host embodiment tunable.

[0044] Optionally, a liquid filter material 140 (e.g., a solvent plus a metal ion solution) can be used as a medium to cool the light source 100. For example, a light bulb or other light generating source 102 can be thermally coupled to the liquid filter solution, which allows the solution to absorb heat emitted from the light bulb 102. The solvent of the liquid filter solution (such as, but not limited to, water) can act as a cooling fluid that absorbs and dissipates heat, regulating the temperature of the light source 100 and improving energy efficiency. In a non-limiting embodiment, the liquid filter material 140 can be coupled to the liquid filter solution. Figure 1 The light generating source 102 (eg, a light bulb) is in direct physical contact with the cavity 108 in the cavity.

[0045] In other embodiments, the liquid host matrix is ​​not water. For example, a halide salt of a metal ion may be insoluble in the non-aqueous liquid host. The metal ion can be prepared with an alternative anion that enhances its solubility in the non-aqueous liquid solvent. A surfactant can be added to promote the dissolution of the metal ion. A supporting electrolyte with a suitable solubility can be added to stabilize the metal ion. Additionally or alternatively, an electric potential can be applied to the solution to stabilize the oxidation state of the metal ion. The filter 106 can be tuned by changing or modifying the anion of the metal ion salt to change the absorption region and the non-absorption bandpass region.

[0046] The composition of the host matrix, whether solid or liquid, affects the absorption region of the metal ions that act as the primary filter. For example, changing the host matrix material can cause the absorption region to shift to longer or shorter wavelengths. Figure 6 A graph 180 showing an absorption spectrum 182 of a first filter material is depicted. Figure 7 A graph 184 is depicted showing an absorption spectrum 186 of a second filter material. Both graphs 180, 184 show the same wavelength range. Both filter materials have the same type of metal ions. The only difference is that the first filter material ("matrix X") has a different main matrix than the second filter material ("matrix Y"). Figure 7 As shown, changing the host matrix from "X" to "Y" changes the bandpass region 188 from between about 220 nm and about 240 nm to between about 235 nm and about 255 nm. The wavelength selective filter 106 described herein utilizes this operating principle or phenomenon to tune or adjust the bandpass (transparency) and bandstop (absorption) regions of the filter 106. For example, the characteristics of the metal ions present and the composition of the host matrix are selected to provide a filter material having a desired narrow bandpass region. Thus, if the desired UV light wavelength is 250 nm, then Figure 7 The main matrix Y in should be used to allow the specified wavelength to pass through the filter 106. On the other hand, if the desired wavelength is 230nm, then Figure 6 The main matrix X in .

[0047] The desired narrowband bandpass region can represent a narrow range of wavelengths that includes one or more wavelengths associated with a desired property, such as effectively neutralizing bacteria and viruses without harming human tissue, even during prolonged exposure to filtered UV light. For example, the filter 106 is tuned so that the emitted UV light exhibits a specified wavelength or narrow range of wavelengths that is safe (e.g., harmless) to human tissue. For example, the specified wavelength can be 222 nm. Thus, even if Figure 1The UV light 100 in the illumination field continuously emits UV light to the passengers of the vehicle during the journey of the vehicle, such as during the flight of an airplane, and the passengers are not harmed. The filter 106 absorbs or dissipates wavelengths outside the specified wavelength or narrow band, so that the UV light emitted in the illumination field consists only of the specified narrow band wavelength range.

[0048] In a non-limiting example, the designated wavelength is 222 nm. Disinfecting UV light with a wavelength of 222 nm has been found to kill pathogens (such as viruses and bacteria) rather than inactivate them. In contrast, UVC light with a wavelength of 254 nm can inactivate pathogens by interfering with their DNA, resulting in temporary inactivation but likely not killing them. Instead, pathogens can be reactivated by exposure to ordinary white light at a reactivation rate of approximately 10% per hour. Therefore, UVC light with a wavelength of 254 nm may be ineffective in illuminated areas, such as the interior cabin of a vehicle. Furthermore, UVC light with a wavelength of 254 nm is not recommended for human exposure because it may be able to penetrate human cells. In contrast, disinfecting UV light with a wavelength of 222 nm is safe for human exposure and can kill pathogens. Furthermore, disinfecting UV light with a wavelength of 222 nm can be emitted at full power within a millisecond or less of the time the UV lamp 120 is activated (compared to UVC light with a wavelength of 254 nm, which may take several seconds or even minutes to reach full power). In a non-limiting embodiment, the selective wavelength filter 106 is designed to have a narrow passband region including the desired wavelength of 222 nm and a light-blocking (e.g., absorbing) band-stop region extending from approximately 225 nm to approximately 270 nm. Thus, 222 nm UV light is transmitted through the filter 106 with high transmittance, while 254 nm UV light and other wavelengths in the band-stop region are absorbed and blocked.

[0049] The selective wavelength filter 106 can show luminescence under deep UV radiation, which may be undesirable in some applications. This luminescence can emit light in the UV-B, UV-A or visible spectrum region. If desired, various changes can be made to the selective wavelength filter 106 to reduce or quench the luminescence. For example, the luminescence can be downconverted so that the filter mainly emits light in the visible spectrum (above 400nm). In order to complete the downconversion, in addition to the metal ions as the main filter agents, transition metal ions or their combination can be added to the main matrix. Under UV irradiation, the metal ions as the main filter agents absorb some incident light and then transfer the excitation energy to the transition metal ions, which then release the excitation energy in the form of visible photons. The metal ions can directly transfer energy (for example, short-range interaction). Alternatively, the UV filter can emit fluorescence and emit light, and the transition metal ions can reabsorb this light and re-emit downconverted light (for example, long-range interaction). The transition metal ions can be Mn ions that emit about 600nm. 2+ Alternatively, a transition metal with a low quantum yield of radiation can be selected to reduce the total amount of luminescent intensity. The emission of visible light can be used to indicate to the operator of the present invention that the filter 106 is under UV illumination. UV illumination is invisible to the human eye, and it may not be obvious whether the UV light source is on or off. If the filter 106 is used with a UV light source, it will emit some visible radiation, and the user of the UV light source will then know that the UV light source is on.

[0050] In another embodiment, luminescence can be quenched by operating the filter 106 at high temperatures. At high temperatures, the absorption and emission bands of the metal ions overlap and lead to quenching of light emission. In addition, high temperatures promote the occupation of vibrational excitation modes, which tends to increase the rate of non-radiative decay. The heating element that provides the high temperature can be the UV light source itself. Alternatively, discrete heating elements can be intentionally installed on the side of the filter 106 to heat the filter 106 without obstructing the path of light from the UV source and leaving the filter 106.

[0051] Figure 8 2 is a flow chart of a method for selectively filtering UV light according to an embodiment. The method in various embodiments utilizes and / or provides one or more aspects discussed above in connection with the example wavelength selective filter 106 discussed herein. It should be noted that in various embodiments steps may be added or omitted, and / or may be performed in a manner similar to that described above. Figure 8 The various steps may be performed in a different order as shown.

[0052] At 202, the main matrix is ​​doped with metal ions to form a filter material with a bandpass region within the deep UV range. The deep UV range can be between approximately 190nm and approximately 280nm, including endpoint values. Due to doping, the metal ions are dispersed in the main matrix. Optionally, doping the main matrix with metal ions can include adding a salt comprising the metal ions to the main matrix while heating the main matrix.

[0053] Optionally, the host matrix is ​​a liquid. For example, doping at 202 may include dissolving a salt comprising metal ions in a water-based solution representing the host matrix. When the host matrix is ​​a liquid, the method includes, at 204, pouring the host matrix (pre-doped) and / or the filter material (post-doped) into a container transparent to light in the deep UV range. In embodiments where the host matrix is ​​not a liquid, step 204 may be omitted.

[0054] At 206, a filter material is mounted on the light source in a light propagation path of light emitted by the light source bulb. Once in position, at 208, the filter material filters the light in the light propagation path. The filter material can allow a first portion of light having wavelengths within a passband region to be transmitted through the filter material, while simultaneously blocking a second portion of light having wavelengths outside the passband region from being transmitted through the filter material. Thus, the filter material enables the first portion of light to be transmitted through the filter material along the light propagation path, while absorbing or otherwise blocking the emission of a second portion of light.

[0055] The following strategies are applicable to quenching luminescence in embodiments utilizing a solid host matrix. Non-radiative impurities are (intentionally) introduced into the host matrix to quench the luminescence of the metal ion(s) serving as the primary filter. The impurity may have the same charge as one of the components in the host matrix, but a different size. If the host matrix is ​​an alkali halide, the impurity is an alkali metal in addition to forming part of the host matrix, or the impurity is a halogen in addition to forming part of the host matrix. If the host matrix is ​​an alkaline earth halide, the impurity is an alkaline earth metal in addition to forming part of the host matrix, or the impurity is a halogen in addition to forming part of the host matrix.

[0056] Alternatively, the impurity may have a different charge and size than the individual components of the host matrix. If the host matrix is ​​an alkali halide, the impurity may be an alkaline earth metal. If the host matrix is ​​an alkaline earth halide, the impurity may be an alkali metal.

[0057] In another embodiment, the impurity is an oxide ion, oxygen gas or sulfide ion. In addition to the halide form of the metal ion, an oxide or sulfide compound of the metal ion used as the primary filter can also be introduced into the main matrix, thereby introducing the oxide or sulfide ion into the main matrix as an impurity.

[0058] In another embodiment, the impurity is a metal oxide or a combination of metal oxides such that the metal(s) are not present in the host matrix.

[0059] In another embodiment, the impurity is water, or some other molecule that is liquid at room temperature. The impurity can be a derivative of water, for example, hydroxide ions (OH - ).

[0060] Luminescence can be quenched by producing a phenomenon called "concentration quenching", which involves the metal ions (one or more) used as primary filter agents being closely packed together in a solid matrix. Metal ions (one or more) are used in sufficiently high concentrations so that when absorbing UV photons, the metal ions can transfer their excitation energy to nearby metal ions. Along with each continuous energy transfer, the probability of encountering defects in the host matrix increases. When encountering defects, the excitation energy is dissipated without emitting photons. Optionally, metal ions (one or more) can be intentionally forced to gather in the main matrix and form clusters with a high local density of metal ions. This can produce defects in the main matrix, thereby promoting the quenching of metal ions (one or more). Clustering can be induced by using high concentrations of metal ions and / or via a preparation method. The preparation method can include heating the main matrix, applying metal ions to the main matrix, then allowing the main matrix to slowly cool, and as the matrix solidifies, allowing the metal ions (one or more) to diffuse mutually.

[0061] When metal ions are dissolved in a liquid matrix, the following strategies are applicable to luminescence quenching. In the first strategy, oxygen is intentionally dissolved in the liquid to quench the luminescence of the metal ions. Oxygen can be introduced into the liquid using pure oxygen or by using a gas mixture containing some oxygen, such as ambient air. Alternatively, a gas-permeable separator can be used in a housing surrounding the liquid to allow oxygen to diffuse into the liquid.

[0062] In the second strategy using a liquid host matrix, a liquid different from the liquid comprising the host matrix is ​​mixed into the host matrix to quench the luminescence of the metal ions. The third strategy involves adding a surfactant to the host matrix to induce aggregation of the metal ions, resulting in concentration quenching.

[0063] As described herein, embodiments of the present disclosure provide a filter for selectively filtering deep UV light. The filter can be designed to transmit a narrow wavelength range encompassing one or more desired wavelengths while blocking wavelengths in a range adjacent to the narrow range. The one or more desired wavelengths can be used to sterilize and disinfect surfaces, air, and people within the interior of a vehicle without harming people exposed to the UV light.

[0064] Furthermore, the present disclosure includes implementations according to the following clauses:

[0065] Item 1: A wavelength selective filter comprising: a filter material including a main matrix doped with metal ions; the filter material having a transmission region in a deep ultraviolet (UV) range such that UV light in the transmission region is transmitted through the filter material.

[0066] Item 2: The wavelength selective filter of Item 1, wherein the deep UV range is between about 190 nm and about 280 nm.

[0067] Item 3. The wavelength selective filter according to any one of Items 1 or 2, wherein the width of the transmissive region is no greater than 30 nm.

[0068] Clause 4. The wavelength selective filter according to any one of clauses 1-3, wherein the transmission region includes a specified wavelength or a narrow wavelength range that is safe for human tissue.

[0069] Clause 5. The wavelength selective filter of Clause 4, wherein the designated wavelength is 222 nm.

[0070] Clause 6. The wavelength selective filter according to any one of clauses 1-5, wherein the metal ions comprise one or more of thallium, indium, tin, lead, or bismuth.

[0071] Clause 7. The wavelength selective filter of any one of clauses 1-6, wherein the position and width of the transmissive region along the electromagnetic spectrum is based on the identity of the metal ions and the composition of the host matrix.

[0072] Clause 8. The wavelength selective filter according to any one of clauses 1 to 7, wherein the main matrix is ​​solid.

[0073] Clause 9. The wavelength selective filter according to any one of clauses 1 to 8, wherein the host matrix is ​​one of an alkali metal halide, an alkaline earth metal halide, a metal oxide, a metal fluoride, or a metal nitride.

[0074] Clause 10. A wavelength selective filter according to any one of clauses 1-9, wherein the filter material is a first filter material defining a first layer, and the wavelength selective filter includes a second filter material defining a second layer stacked with the first layer; the second filter material includes a main matrix doped with metal ions, and at least one of the main matrix of the second filter material or the metal ions of the second filter material is different from the first filter material.

[0075] Clause 11. The wavelength selective filter according to any one of clauses 1 to 10, wherein the host matrix is ​​a liquid.

[0076] Item 12. The wavelength selective filter according to Item 11, wherein the host matrix comprises water and an additive for stabilizing the metal ions in the water.

[0077] Item 13. The wavelength selective filter according to Item 11, further comprising a container enclosing the liquid host matrix; the container being transparent to light in the deep UV range.

[0078] Clause 14. The wavelength selective filter of Clause 13, wherein the container is doped with metal ions.

[0079] Item 15. A method for selectively filtering ultraviolet (UV) light, the method comprising: doping a main matrix with metal ions to form a filter material having a transmission region in a deep UV range between about 190 nm and about 280 nm; the metal ions dispersed in the main matrix; the method comprising: mounting the filter material on the light source in a light propagation path of light emitted by a bulb of the light source, and filtering the light in the light propagation path via the filter material such that a first portion of light having a wavelength within the transmission region is transmitted through the filter material, and a second portion of light having a wavelength outside the transmission region is not transmitted through the filter material.

[0080] Item 16. The method of Item 15, wherein doping the host matrix with the metal ions comprises adding a salt comprising the metal ions to the host matrix while heating the host matrix.

[0081] Clause 17. The method according to any one of Clauses 15 or 16, wherein doping the host matrix with the metal ions comprises dissolving a salt comprising the metal ions in a water-based solution representing the host matrix.

[0082] Clause 18. The method of any one of Clauses 15-17, wherein the primary matrix is ​​a liquid and the method further comprises pouring the primary matrix into a container; the container being transparent to light in the deep UV range.

[0083] Item 19: A light source comprising: a housing, a bulb, and a wavelength selective filter; the bulb is held by the housing and configured to emit ultraviolet (UV) light; the wavelength selective filter is disposed in a light propagation path of the UV light emitted by the bulb; the wavelength selective filter comprises a filter material having a main matrix doped with metal ions; the filter material has a transmission region within a deep ultraviolet (UV) range; wherein a portion of the UV light emitted by the bulb having a wavelength within the transmission region is transmitted through the wavelength selective filter.

[0084] Clause 20: The light source of clause 19, wherein the transmissive region includes a specified wavelength or narrow wavelength range that is safe for human tissue.

[0085] Although various spatial and directional terms may be used to describe embodiments of the present disclosure, such as top, bottom, lower, middle, lateral, horizontal, vertical, front, etc., it should be understood that these terms are only used in relation to the orientation shown in the drawings. The orientation may be reversed, rotated, or otherwise changed so that top is lower and vice versa, horizontal becomes vertical, etc.

[0086] As used herein, a structure, limitation, or element that is "configured to" perform a task or operation is specifically formed, constructed, or adapted structurally in a manner corresponding to the task or operation. For purposes of clarity and the avoidance of doubt, an object that is merely capable of being altered to perform a task or operation is not "configured to" perform a task or operation as used herein.

[0087] As used herein, numerical modifiers such as “about,” “substantially,” and “approximately” inserted before a numerical value indicate that the value may represent other values ​​above and / or below the specified value within a specified threshold range, such as values ​​within 5%, 10%, or 15% of the specified value.

[0088] It should be understood that the above description is intended to be illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. In addition, many changes can be made to adapt specific situations or materials to the teachings of the various embodiments of the present disclosure without departing from its scope. Although the sizes and types of materials described herein are intended to limit the parameters of the various embodiments of the present disclosure, these embodiments are by no means restrictive, but rather exemplary embodiments. After reading the above description, many other embodiments will be apparent to those skilled in the art. Therefore, the scope of the various embodiments of the present disclosure should be determined with reference to the appended claims and the full scope of equivalents granted by these claims. In the appended claims and the detailed description herein, the terms "including" and "in which" are used as the plain English equivalents of the corresponding terms "comprising" and "wherein". In addition, the terms "first", "second", and "third" are used only as labels and are not intended to impose numerical requirements on their objects. Further, the claim limitations are not drafted in means-plus-function format and are not intended to be interpreted under 35 U.S.C. §112(f) unless and until such claim limitation expressly uses the phrase "means for" followed by a description of the function without further structure.

[0089] This written description uses examples to disclose various embodiments of the disclosure, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the disclosure is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A wavelength selective filter (106), comprising: A filter material (140) comprising a main matrix (142) doped with metal cations (144), the filter material (140) having a transmission region (156, 188) in the deep ultraviolet range, such that ultraviolet light with a wavelength within the transmission region (156, 188) is transmitted through the filter material (140) and ultraviolet light with a wavelength above and below the transmission region (156, 188) is blocked in the deep ultraviolet range, wherein the metal cations (144) include a first metal cation having a first absorption spectrum (151) and a second metal cation having a second absorption spectrum (152), wherein a combined absorption spectrum (155) defined by the absorption ranges of the first metal cation and the second metal cation defines the transmission region (156, 188), wherein the deep ultraviolet range is between 190 nm and 280 nm, and The width of the transmission region (156, 188) is no greater than 30 nm.

2. The wavelength selective filter (106) of claim 1, wherein the transmission region (156, 188) includes a specified wavelength or a narrow wavelength range that is safe for human tissue.

3. The wavelength selective filter (106) according to claim 2, wherein the designated wavelength is 222 nm.

4. The wavelength selective filter (106) of claim 1, wherein the metal cations (144) include one or more of thallium, indium, tin, lead, or bismuth.

5. The wavelength selective filter (106) of claim 1, wherein the position and width of the transmission region (156, 188) along the electromagnetic spectrum are based on the characteristics of the metal cations (144) and the composition of the host matrix (142).

6. The wavelength selective filter (106) according to claim 1, wherein the main matrix (142) is a solid.

7. The wavelength selective filter (106) according to claim 6, wherein the host matrix (142) is one of alkali metal halides, alkaline earth metal halides, metal oxides, metal fluorides or metal nitrides.

8. A wavelength selective filter (106) according to claim 1, wherein the filter material (140) is a first filter material defining a first layer (A), and the wavelength selective filter (106) includes a second filter material defining a second layer (B) stacked together with the first layer, the second filter material includes a main matrix (142) doped with metal cations (144), and at least one of the main matrix (142) of the second filter material or the metal cations (144) of the second filter material is different from the first filter material.

9. The wavelength selective filter (106) according to claim 1, wherein the main matrix (142) is a liquid.

10. The wavelength selective filter (106) according to claim 9, wherein the main matrix (142) comprises water and an additive for stabilizing the metal cations (144) in the water.

11. The wavelength selective filter (106) according to claim 9, further comprising a container enclosing the liquid host matrix (142), the container being transparent to light in the deep ultraviolet range.

12. The wavelength selective filter (106) of claim 11, wherein the container is doped with metal cations (144).

13. A method (200) for selectively filtering ultraviolet light, the method comprising: doping a host matrix (142) with metal cations (144) dispersed in the host matrix (142) to form a filter material (140) having a transmission region (156, 188) in the deep ultraviolet range between 190 nm and 280 nm; Mounting the filter material (140) on the light source (100) in a light propagation path of light emitted by the light source (100); and filtering the light in the light propagation path via the filter material (140) such that a first portion of the light having a wavelength within the transmission region (156, 188) is transmitted through the filter material (140) and a second portion of the light having a wavelength within the deep ultraviolet range and outside the transmission region (156, 188) is not transmitted through the filter material (140), wherein the metal cations (144) include a first metal cation having a first absorption spectrum (151) and a second metal cation having a second absorption spectrum (152), wherein a combined absorption spectrum (155) defined by the absorption ranges of the first metal cation and the second metal cation defines a transmission region (156, 188) shaped by the absorption ranges of the first metal cation and the second metal cation, and The width of the transmission region (156, 188) is no greater than 30 nm.

14. The method (200) of claim 13, wherein doping the host matrix (142) with the metal cations (144) comprises adding a salt comprising the metal cations (144) to the host matrix (142) while heating the host matrix (142).

15. The method (200) of claim 13 or 14, wherein doping the host matrix (142) with the metal cations (144) comprises dissolving a salt comprising the metal cations (144) in a water-based solution representing the host matrix (142).

16. The method (200) of claim 13 or 14, wherein the main matrix (142) is a liquid and the method (200) further comprises pouring the main matrix (142) into a container, the container being transparent to light in the deep ultraviolet range.

17. A light source (100), comprising: housing (104); a light generating source (102) held by the housing and configured to emit ultraviolet light; and A wavelength selective filter (106) is provided in a light propagation path of the ultraviolet light emitted by the light generating source (102), the wavelength selective filter (106) comprising a filter material (140) having a main matrix (142) doped with metal cations (144), the metal cations (144) comprising one or more of thallium, indium, tin, lead or bismuth, the filter material (140) having a transmission region (156, 188) in the deep ultraviolet range, the transmission region (156, 188) comprising 222 nm, wherein a portion of the ultraviolet light emitted by the light generating source having a wavelength within the transmission region (156, 188) is transmitted through the wavelength selective filter (106).

18. The light source of claim 17, wherein the transmissive region (156, 188) includes a specified wavelength or narrow wavelength range that is safe for human tissue.

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