DIFFUSER

The present application claims priority benefit from U.S. Provisional Patent Application No. 63/348,439, entitled “FAR ULTRAVIOLET LAMP AND SYSTEM WITH ILLUMINATION DIFFUSER”, filed June 6, 2022 (docket number 3083-004- 02), which, to the extent not inconsistent with the disclosure herein, is incorporated by reference in its entirety.

The present application claims priority benefit from from International PCT Patent Application No. PCT/US2023/064268, entitled “EXCIMER ILLUMINATOR WITH REPLACEABLE LAMP”, filed March 13, 2023 (docket number 3083-006- 04), currently pending; from International PCT Patent Application No. PCT/US2023/064269, entitled “REPLACEABLE EXCIMER LAMP”, filed March 13, 2023 (docket number 3083-011-04), currently pending; from International PCT Patent Application No. PCT/US2023/061608, entitled “ULTRAVIOLET ILLUMINATOR WITH NETWORK COMMUNICATION”, filed January 30, 2023 (docket number 3083-003-04), currently pending; and from International PCT Patent Application No. PCT/US2022/077822, entitled “IMPROVED DISINFECTION LIGHTING SYSTEMS AND METHODS”, filed October 7, 2022 (docket number 3083-001-04), currently pending; each of which, to the extent not inconsistent with the disclosure herein, is incorporated by reference. SUMMARY

According to an embodiment, an excimer lamp includes a quartz glass tube holding krypton and a halogen that form a gas characterized by an excimer discharge energy including ultraviolet light emission between at least a portion of a range delimited by 200 nanometers and 235 nanometers wavelength, which is invisible to a human eye. An electrode pair is mechanically supported by or adjacent to the quartz glass tube configured to, when an alternating voltage is applied, capacitively charge the gas to form a Kr-CI or Kr-Br excited complex, whereupon the gas undergoes the excimer discharge when the krypton and halogen dissociate. An optical diffuser disposed in an illumination path optically aligned between the quartz glass tube and an illuminated region, suitable for human occupation, converts the excimer discharge to an emission pattern approaching Lambertian emission. According to an embodiment, the optical diffuser includes poly-tetra-fluoro-ethylene (PTFE).

According to an embodiment, a far ultraviolet illuminator includes a housing defining an illumination aperture, an electronic circuit disposed in the housing and configured to output an alternating current to two or more electrical connection points for supply to an excimer lamp electrode pair, a mechanical coupler configured to hold the excimer lamp at least partially within a volume defined by the housing and in alignment with the illumination aperture, and an optical diffuser configured to convert far ultraviolet illumination emitted from the excimer lamp and illumination aperture to diffuse illumination such as Lambertian emission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side-sectional diagram of an excimer lamp, according to an embodiment.

FIG. 1B is a cross-sectional diagram of the excimer lamp of FIG. 1A, according to an embodiment.

FIG. 1C is a cross-sectional diagram of the excimer lamp of FIG. 1A, wherein the quartz glass tube is configured as a planar quartz glass package, according to an embodiment.

FIG. 2 is a diagram of an excimer lamp including a lamp assembly, according to an embodiment.

FIG. 3 is a diagram of the excimer lamp of FIG. 2, showing an arrangement of an optical diffuser, according to an embodiment.

FIG. 4A is a diagram of a luminaire configured to hold the excimer lamp of FIGS 1A and 2, according to an embodiment.

FIG. 4B is a diagram of a luminaire including an alternative window arrangement, according to an embodiment.

FIG. 5 is a cross-sectional diagram of an excimer lamp including a plurality of quartz glass tubes, according to an embodiment. FIG. 6 is a sectional diagram of an excimer lamp including electrodes arranged to create a plurality of transverse discharges in a krypton and halogen gas, according to an embodiment.

FIG. 7 is a diagram of an enhanced optical diffuser disposed relative to a quartz glass tube, the enhanced optical diffuser including features for increasing light intensity off-axis in the illuminated region, according to an embodiment.

FIG. 8 is a conceptual diagram illustrating ultraviolet light emission with a broadened and flattened illumination pattern with an optical diffuser compared to an illumination pattern without an optical diffuser according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.

For economy of language, as used herein the term “excimer” (derived from the term EXcited dIMER) will be understood to extend to non-homogenious atom pairings including a noble gas atom and a halogen gas atom. In the literature, this is sometimes referred to as “exciplex” (derived from the term EXCIted comPLEX). Excimer lamps operate by charging atoms to a high energy state corresponding to atomic pairing, followed by fast discharge to a lower energy state as the atoms dissociate.

The discharge energy of interest output by systems described herein includes photonic emission between 200 and 235 nanometers. In an embodiment, the discharge energy output includes photonic emission between 200 and 230 nanometers. In another embodiment, the discharge energy output includes photonic emission between 200 and 240 nanometers.

Specifically, a krypton-chlorine excimer lamp has a nominal discharge wavelength of 222 nanometers. Akrypton-bromine excimer lamp has a nominal output wavelength of 207 nanometers. Band spreading and other effects can cause longer or shorter wavelength output. For example, a pairing Kr-Kr has a nominal output at 146 nanometers, CI-CI has a nominal output at 259 nanometers, and Br-Br has a nominal output at 289 nanometers. Typically undesirable wavelengths outside the intended 200 to 230, 200 to 235, or 200 to 240 nanometers are filtered or otherwise suppressed to prevent transmission into a space occupied by humans.

It has been found that illumination of bacteria and/or virus particles in air, in an aerosol, and/or on a surface by light at 200-235 nanometers wavelength causes disinfection (loss of the ability to infect most humans) while also being eye- and skin-safe under controlled (moderate) exposure.

For this reason KrCI and KrBr lamps are attractive for reducing viral exposure in human-occupied spaces. For economy of language, the terms far ultraviolet and far LIVC will be considered synonymous and will be understood to refer to ultraviolet wavelengths between 200 and 235 nanometers, wavelengths between 200 and 230 nanometers, or wavelengths between 200 and 240 nanometers or a range comprehended thereby.

FIG. 1A is a side-sectional view of an excimer lamp 100, according to an embodiment. The excimer lamp 100 includes a quartz glass tube 102 holding krypton and a halogen that form a gas 104 characterized by an excimer discharge 116 energy including far UVC ultraviolet light emission between at least a portion of a range delimited by 200 nanometers and 235 nanometers wavelength. The far UV emission is typically invisible to a human eye and also generally non-damaging to human tissues. An electrode pair 106 may be mechanically supported by or adjacent to the quartz glass tube 102. The electrode pair 106 is configured to, when an alternating voltage is applied via the electrode pair 106, capacitively charge the gas to form a Kr-CI or Kr-Br excited complex, whereupon the gas undergoes the excimer discharge 116 when the krypton and halogen dissociate. An optical diffuser 108 is disposed in an illumination path 110 optically aligned between the quartz glass tube 102 and an illuminated region 112 suitable for human occupation.

The optical diffuser 108 causes spreading of the far UV illumination substantially across a hemisphere as Lambertian radiation.

In an embodiment, the quartz glass tube 102 is formed from fused silica. In another embodiment, the quartz glass tube 102 is formed from fused quartz. The optical diffuser 108 may include a poly-tetra-fluoro-ethylene (PTFE) optical diffuser 108. In an embodiment, the PTFE optical diffuser 108 is between 0.001 inch and 0.015 inch thickness. The PTFE optical diffuser 108 may be less than 0.010 inch thick. In another embodiment, the PTFE optical diffuser 108 may be less than 0.007 inch thick. For example, the PTFE optical diffuser 108 may be less than 0.005 inch thickness. In another embodiment, the PTFE optical diffuser 108 is less than 0.004 inch thick. In an embodiment, the PTFE optical diffuser 108 is 0.001 inch thick. In an embodiment, the PTFE optical diffuser 108 is coated onto the quartz glass with a thickness of less than .001 inch.

Alternatively, a thicker PTFE optical diffuser 108 may be used. In embodiments, the PTFE optical diffuser 108 is greater than 0.015 inch thickness. The PTFE optical diffuser 108 may be greater than 0.020 inch thickness. In an embodiment, the PTFE optical diffuser 108 is about 0.031 inch thickness.

In an embodiment, the optical diffuser 108 is disposed substantially in contact with or coincident with a surface 114 of the quartz glass tube 102. The quartz glass tube 102 may include a single-walled tube containing the krypton and halogen gas 104.

FIG. 1 B is a cross-sectional diagram 117 of the excimer lamp 100 of FIG. 1A, according to an embodiment wherein the quartz glass tube 102 is cylindrical. FIG. 1C is a cross-sectional diagram 119 of the excimer lamp 100 of FIG. 1 A, wherein the quartz glass tube 102 is configured as a planar quartz glass package, according to an embodiment. In another embodiment (not shown), the quartz glass tube 102 includes an outer tube disposed at an outer radius from a center and an inner tube disposed at an inner radius, less than the outer radius, from the center. The krypton and halogen gas 104 is contained in a torroidal volume between the inner and outer tubes. A first electrode 106a of the electrode pair 106 may be disposed in an air space within the inner radius. A second electrode 106b of the electrode pair 106 may be disposed around the outer tube outside the outer radius. The first and second electrodes 106a, 106b may cooperate to apply an alternating field along radial directions through the krypton and halogen gas 104.

FIG. 2 is an example of an excimer lamp 100, 200 including a quartz glass tube 102 and an optical diffuser 108 separated from a surface 114 of the quartz glass tube 102 by an air gap 202, according to an embodiment. In an embodiment, the excimer lamp 100 includes at least one quartz glass tube 102 arranged relative to the pair of electrodes to respectively create a longitudinal discharge 116 through the krypton and halogen gas 104.

FIG. 2 is also a diagram of an excimer lamp 200 including a lamp assembly 204, according to an embodiment. The lamp assembly 204 may include the pair of electrodes 106 disposed adjacent to the quartz glass tube 102, and a first window 206, through which at least a portion of the far ultraviolet light emission 110 is transmitted.

The inventors contemplate several arrangements for using an optical diffuser to produce a far UV radiation pattern that more closely approaches Lambertian radiation than an excimer lamp or luminaire that does not include an optical diffuser. In an embodiment, the optical diffuser 108 and the first window 206 are coextensive. In an embodiment, the first window 206, coextensive with the optical diffuser 108, is formed from PTFE. In another embodiment, the optical diffuser 108 is disposed adjacent to an outer surface 208 of the first window 206, the outer surface 208 being disposed away from the quartz glass tube 102.

The first window 206 may include a quartz window formed from fused silica or fused quartz. In another embodiment, the first window 206 includes or consists essentially of a metal screen.

FIG. 3 is a diagram 300 of an excimer lamp 100, 200 including a quartz glass tube 102 and an optical diffuser 108 disposed on an inside surface 302 of the first window 206, the inside surface 302 facing the quartz glass tube 102, according to an embodiment.

In an embodiment, the first window 206 includes an optical filter 416 (e.g., see FIG. 4A) configured to substantially restrict ultraviolet light 110 transmission to the illuminated region 112 to a passband between 200 nanometers and 235 nanometers (or alternatively, another passband as described above). In an embodiment, the optical filter 416 is disposed adjacent to the optical diffuser 108. In another embodiment, the optical filter 416 and the optical diffuser 108 are disposed adjacent to a surface of the quartz glass tube 102 (arrangement not shown).

FIG. 4A is a diagram of a luminaire 400 holding an excimer lamp 100, 200, according to an embodiment. FIG. 4B is a diagram of a luminaire 401 including an alternative window arrangement, according to an embodiment. Referring to FIGS. 4A and 4B, a luminaire housing 402 configured to house at least one quartz glass tube 102 and the at least one electrode pair 106. In the particular embodiment 400, the luminaire housing 402 is configured to house an excimer lamp 100, 200 including an lamp assembly 204.

The luminaire housing 402 defines an aperture 404 for transmitting the far UVC ultraviolet light emission 110 through the illu m inatin path to the illuminated region 112. The optical diffuser 108 may form a second window 406 disposed in the aperture 404. According to an embodiment, the optical diffuser 108 is disposed in or adjacent to the aperture 404. The optical diffuser 108 may be coextensive with or formed as one or both surfaces of the second window 406. In the embodiment 400, the optical diffuser 108 is disposed adjacent to the second window 406 disposed in the aperture 404. In the illustrated embodiment, the optical diffuser 108 may be held against an outside surface of the second window 406. In another embodiment , the optical diffuser 108 may be adjacent to and supported by a second window 406 disposed in the aperture 404. In an embodiment, the optical diffuser 108 is disposed on a surface of the second window 406. The optical diffuser 108 may be disposed on an inner surface of the second window 406, or may additionally or alternatively be disposed on an outer surface of the second window 406.

In an embodiment, the second window 406 disposed in the aperture 404 may include a half-cylinder at least partially protruding from a front surface 414 of the luminaire 400. The optical diffuser 108 may be disposed coincident with the half cylinder, on an inner surface of the half cylinder, or on an outer surface of the half cylinder.

FIG. 5 is a sectional diagram 500 of an excimer lamp 100, 200 including a plurality of quartz glass tubes 102a, 102b, 102c, according to an embodiment. FIG. 6 is a sectional diagram of an excimer lamp 600 including electrodes 106a, 106b arranged to create a plurality of transverse discharges 116a, 116b, 116c, 116d, 116e, 116f in the krypton and halogen gas 104, according to an embodiment. Referring to FIGS 5 and 6, The transverse discharge 116 arrangement 600 may be configured as a single quartz glass tube 102, or may include a plurality of quartz glass tubes 102a, 102b, 102c .

As indicated above, the optical diffuser 108 may include PTFE. In an embodiment, the halogen includes bromine. In an embodiment, the halogen consists essentially of chlorine. When the excimer lamp 100, 200 includes substantially all Kr-CI, and substantially all of the excimer discharge 116 is exciplex discharge centered at 222 nanometer wavelength.

FIG. 7 is a diagram 700 of an enhanced optical diffuser 108 disposed relative to a quartz glass tube 102, the enhanced optical diffuser 108 including features 702 for increasing light intensity off-axis in the illuminated region, according to an embodiment.

FIG. 8 is a conceptual diagram 800 illustrating ultraviolet light emission with a broadened and flattened illumination pattern 802, 806 with an optical diffuser compared to an illumination pattern 804 without an optical diffuser, according to an embodiment. Referring to FIGS. 1A - 8, the optical diffuser 108 may be arranged for broadening the ultraviolet light emission 110 to the illuminated region 112. The optical diffuser 108 may be arranged for reducing variation in intensity of the ultraviolet light emission 110 to the illuminated region 112.

The optical diffuser 108 may include one or more features 702 configured to transmit non-diffused ultraviolet emission in directions away from a centerline of illumination into the illuminated region 112. The optical diffuser 108, 208 may include a PTFE film, and the one or more features 702 may include a plurality of holes in the PTFE film. In another embodiment the optical diffuser 108 includes a textured glass panel and the one or more features 702 include a plurality of regions of untextured or reduced texture glass surface. The texture on the glass panel may include a number of optional treatments. For example, the texture may include ground glass, a phase mask, and/or an ordered or pseudo blue noise fade. In the case of a phase mask or fade pattern, explicit features 702 may be omitted, with their function being provided by the texture. The optical diffuser 108 may include a textured transmissive surface, a reflective surface and/or a diffractive surface.

According to an embodiment, a reflector is configured to direct the ultraviolet emission 110 toward the optical diffuser 108, 208. The reflector may include a hyperbolic reflector. The reflector may include the optical diffuser 108, 208. The reflector may include a second optical diffuser, such as a second optical diffuser configured to cooperate with the optical diffuser to output a desired field of view. In an embodiment, one or more lenses (or equivalently, reflective or diffractive elements) may cooperate to control the output field of view.

Referring again to FIG. 4A, according to an embodiment, a far ultraviolet illuminator 400 includes a housing 402 defining an illumination aperture 404. An electronic circuit 408 may be disposed in the housing 402 and configured to output an alternating current to two or more electrical connection points 410 for supply to an excimer lamp electrode pair 106. In an embodiment, the circuit 408 drives a square wave across the electrode pair 106. A mechanical coupler (not shown) may be configured to hold the excimer lamp 100, 200 at least partially within a volume 412 defined by the housing 402 and in alignment with the illumination aperture 404. In an embodiment, the excimer lamp 100, 200 may be disposed entirely in a volume 412 behind a front surface 414 of the housing 402. In another embodiment, the excimer lamp 100, 200 may extend partially outside the volume 412, extending outside the front surface 414 of the housing 402. An optical diffuser 108 may be disposed to at least partially transmit the far UVC illumination 110, and may be configured to convert the far UVC illumination emitted from the excimer lamp 100, 200 and illumination aperture 404 to diffuse illumination. The optical diffuser 108 may be configured to convert light 110 from the excimer lamp 100 to substantially Lambertian emission in the illuminated volume 112.

In an embodiment, the optical diffuser includes a PTFE optical diffuser 108. In an embodiment, the PTFE optical diffuser 108 is between 0.001 inch and 0.015 inch thickness. The PTFE optical diffuser 108 may be less than 0.010 inch thick. The PTFE optical diffuser 108 may be less than 0.007 inch thick. For example, the PTFE optical diffuser 108 may be 0.005 inch thickness. In another embodiment, the PTFE optical diffuser 108 is less than 0.004 inch thick. In an embodiment, the PTFE optical diffuser 108 is 0.001 inch thick.

In an embodiment, the PTFE optical diffuser is coated (e.g., solution or suspension coated) onto a surface through which the ultraviolet illumination 110 passes. The coating may vary somewhat in thickness owing to normal process variables. The inventors contemplate a coated PTFE optical diffuser 108 having a thickness less than 0.001 inch when dry.

Alternatively, a thicker PTFE optical diffuser 108 may be used. In embodiments, the PTFE optical diffuser 108 is greater than 0.015 inch thickness. The PTFE optical diffuser 108 may be greater than 0.020 inch thickness. In an embodiment, the PTFE optical diffuser 108 is about 0.031 inch thickness.

According to an embodiment, a far ultraviolet illuminator 400 includes a second window 406 disposed in the illumination aperture 404, aligned for passage of far UVC ultraviolet light 110 from the excimer lamp 100, 200 to pass therethrough. The second window 406 may include quartz glass such as fused quartz or fused silica. In another embodiment, the second window 406 includes a metal screen. The optical diffuser 108 may be disposed adjacent to the second window 406. As depicted in FIG. 4A, the second window 406 may include a flat quartz glass window.

FIG. 4B is a diagram of a luminaire 401 including an alternative window 406 arrangement, according to an embodiment. In the embodiment of FIG. 4B, the second window 406 includes a cylindrical portion, such as a half-cylinder, protruding outside a front surface 414 of the luminaire housing 402. In an embodiment, a mechanical coupler is configured to hold at least a portion of the excimer lamp 100, 200 above the front surface 414 defined by the housing 402 adjacent to the illumination aperture 404. The second window 406 may include a quartz glass half cylinder. In another embodiment, the second window 406 may be formed from a sheet of PTFE. Accordingly, the second window 406 may include the sheet of PTFE formed into a partial cylinder protruding outside a surface 414 of the housing 402. The use of a sheet of PTFE as the second window 406 may be made more practical by using a thicker sheet from a range of PTFE thicknesses.

Referring to FIGS. 1 A - 4B, the second window 406 may include or support the optical diffuser 108. For example, the optical diffuser 108 may be coextensive with or be adjacent to a surface of the second window 406.

In an embodiment, the far ultraviolet illuminator includes an optical filter 416 configured to block 258 nanometer light from passing through the illumination aperture 404. Placement of the optical filter 416 may be coincident with or on a surface of the first window 206. Additionally or alternatively, the optical filter 416 may be coincident with or on a surface of the second window 406 (arrangement not shown). Additionally or alternatively, the optical filter 416 may be disposed on a surface 114 of the quartz glass tube 102. In an embodiment, the optical filter 416 may be configured to attenuate ultraviolet wavelengths longer than 230 nanometers, longer than 235 nanometers, and/or longer than 240 nanometers wavelength from passing through the illumination aperture 404.

The far ultraviolet illuminator 400, 401 may further include an indicator 418, disposed to alert a human outside the housing 402 of a status of the excimer lamp 100, 200 and operatively coupled to the electronic circuit 408. The electronic circuit 408 may be configured to drive the indicator 418 to inform the human of a status of the excimer lamp 100, 200. The indicator 418 may include a sonic indicator 418. Additionally or alternatively, the indicator 418 may include a visible light-emitting-diode (LED).

A visible indicator 418 may be configured to output green light when the excimer lamp 100, 200 has provided illumination for an amount of time within a life expectancy of the excimer lamp 100, 200 or when the excimer lamp 100 is outputting an amount of (invisible) far UVC within a nominal power rating. In an embodiment, the visible indicator 418 is configured to output yellow or amber light when the excimer lamp 100, 200 has provided illumination near an amount of time near an end of a life expectancy of the excimer lamp 100, 200 or with an amount of far UVC at or near a lower limit of the nominal power rating. In an embodiment, the visible indicator 418 is configured to output red light when the excimer lamp 100, 200 has provided illumination for an amount of time exceeding a life expectancy of the excimer lamp 100, 200 or when an intensity of detected far UVC has fallen below the nominal power rating. According to an embodiment the optical diffuser 108 is arranged for broadening the ultraviolet light emission 110 to the illuminated region 112. In an embodiment, the optical diffuser 108 is arranged for reducing variation in intensity of the ultraviolet light emission 110 to the illuminated region 112.

The optical diffuser 108 may include one or more features 702 configured to transmit non-diffused ultraviolet emission 110 in directions away from a centerline of illumination into the illuminated region 112. The optical diffuser 108 may include a PTFE film. The one or more features 702 may include a plurality of holes in the PTFE film. The optical diffuser 108 may include a textured glass panel. The one or more features 702 may include a plurality of regions untextured glass surface. The optical diffuser 108 may include a textured transmissive surface. The textured transmissive surface may include a ground glass surface.

According to an embodiment, a reflector is configured to direct the ultraviolet emission toward the optical diffuser 108. The reflector may include a hyperbolic reflector or other shape configured to direct the ultraviolet emission in a desired direction, as may be made preferable according to aspects of the illuminated region 112. The reflector may include the optical diffuser 108. The reflector may include a second optical diffuser 108. While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.