Aerosol-generating device with laser-based heater

Abstract

An aerosol-generating device (1) for generating an aerosol from an aerosol-generating substrate (3), comprises a heater which is based on a laser emitting element (5) of TCSEL-type. Such selection for the laser emitting element allows reducing a heating time that is necessary for generating sufficient amount of aerosol. Vaping experience is improved for a user of the device.

Description

[0001] AEROSOL-GENERATING DEVICE WITH LASER-BASED HEATER

[0002] The invention relates to an aerosol-generating device which comprises a laser-based heater, a system that comprises this device and an article to be used with it, and also a stick of compressed tobacco that may constitute the article.

[0003] - BACKGROUND OF THE INVENTION -

[0004] Aerosol-generating devices have already been proposed, that implement each a laser source as a heater to generate aerosol from a substrate. However, several issues appear when heating the aerosol-generating substrate through laser irradiation.

[0005] A first issue relates to the time that is necessary to heat the substrate up to a temperature high enough for generating the aerosol in an amount that provides nice vaping sensation to the user from the start of his first puff.

[0006] A second issue relates to radiation losses that may occur in an optical path from the laser source to the aerosol-generating substrate. Indeed, such radiation losses cause the time necessary for the substrate to reach temperature value appropriate for generating the aerosol to increase.

[0007] A third issue relates to the laser source irradiating a constant limited portion of the aerosol-generated substrate, therefore causing the substrate to burn in this portion after some use time. In addition, using the whole substrate for generating aerosol requires waiting for heat which originates from the irradiated substrate portion to diffuse within the article that contains the aerosolgenerating substrate.

[0008] Starting from this situation, one object of the present invention consists in improving vaping experience that is provided to a user of an aerosolgenerating device in which the heater is laser-based.

[0009] In particular, the invention aims at reducing the heating time that is necessary to a laser-based heater for generating aerosol in a suitable amount.

[0010] Another object of the invention consists in allowing utilizing completely or almost completely an amount of aerosol-generating substrate that is contained in an article to be used with a device that implements a laser-based heater.

[0011] Still another object of the invention consists in avoiding that the laser beam originating from the laser source causes part of the aerosol-generating substrate to burn locally.

[0012] - SUMMARY OF THE INVENTION -

[0013] For meeting at least one of these objects or others, a first aspect of the present invention proposes an aerosol-generating device for generating an aerosol from an aerosol-generating substrate, which device comprises:

[0014] - a chamber for accommodating the aerosol-generating substrate; and

[0015] - a heater configured to heat the aerosol-generating substrate when present in the chamber, in order to generate the aerosol, the heater comprising a laser apparatus that comprises a laser emitting element suitable for producing a laser beam configured to generate heat in a heating zone of the aerosol-generating substrate.

[0016] According to the invention, the laser emitting element is of a topological- cavity surface-emitting laser type, commonly known as TCSEL-type. Such selection for the laser emitting element provides the following advantages:

[0017] TCSEL-type laser emitting elements exhibit high optical power values compared with other laser sources, thus allowing reduction of the irradiation time that is necessary for producing enough aerosol amount. Thanks to such high optical power that is available with a TCSEL-type laser emitting element, nice vaping sensation can be experienced by the user from the start of his first puff; the laser beam which is produced by a TCSEL-type laser emitting element exhibits small divergence, thus allowing the radiation losses that may occur in the optical path from the laser emitting element to the aerosol- generating substrate to be low or very low. Such reduction or suppression of the radiation losses participates in reducing the time necessary for the irradiated substrate to reach a temperature value that is appropriate for generating the aerosol in a suitable amount; and the laser beam which is produced by a TCSEL-type laser emitting element exhibits large emission area at the optical output of the laser emitting element. This participates in allowing a larger portion of the aerosolgenerating substrate to be laser-heated and avoids that irradiating a substrate portion that is too small causes the substrate to burn in this portion.

[0018] According to a preferred design of the invention aerosol-generating device, the laser apparatus may further comprise a mirror device which is arranged so that a center emission direction of the laser emitting element is perpendicular to a center propagation direction of the laser beam towards the heating zone. This allows supporting the TCSEL-type laser emitting element by using a planar support, for example a printed circuit board, which is parallel to a longitudinal direction of the aerosol-generating device. Such design facilitates assembling of the aerosol-generating device and thus participates in reducing its unit cost price. It also prevents debris and dirt particles that originate from the article when in the chamber from falling onto the optical output of the laser emitting element.

[0019] According to an improvement of the invention, the laser apparatus may further comprise an optical lens assembly which is arranged on the path of the laser beam from the laser emitting element to the heating zone, this optical lens assembly being designed for modifying a beam cross-sectional area of the laser beam that is effective at the heating zone. Such optical lens assembly allows setting a trade-off about the size of the heating zone at the aerosol-generating substrate, for producing quickly sufficient aerosol amount without burning the substrate in the heating zone. In possible embodiments, the optical lens assembly may comprise two converging lenses and one diverging lens, the diverging lens being located between both converging lenses. Possibly, the optical lens assembly may further comprise an actuator device which is arranged for modifying a position of the diverging lens between both converging lenses, thereby modifying the beam cross-sectional area that is effective at the heating zone, depending on the position of the diverging lens. Preferably, the optical lens assembly may be located between the laser emitting element and the mirror device. Such location for the optical lens assembly avoids that debris and dirt particles that originate from the article when in the chamber fall onto the optical lens assembly.

[0020] According to another improvement of the invention, the laser apparatus may further comprise a lightguide which is located between the mirror device and the heating zone. Such lightguide participates in reducing radiation losses that may occur in the optical path to the aerosol-generating substrate.

[0021] According to a preferred arrangement, when the aerosol-generating device has a proximal end from which a user of this aerosol-generating device inhales the aerosol, and a distal end opposed to the proximal end, the heating zone may be located between the laser apparatus and the proximal end along a longitudinal direction oriented from the distal end to the proximal end. In addition, the heating zone may be located within the chamber at an end thereof which is opposed to the proximal end of the aerosol-generating device.

[0022] Possibly, the heater may further comprise an auxiliary heating element that is separated from the laser apparatus and arranged for heating the aerosolgenerating substrate at least in the heating zone in addition to the heat generated by the laser beam. Thus, the TCSEL-type laser emitting element and the auxiliary heating element can be combined by simultaneous activations thereof for reducing the time necessary for producing the aerosol in an amount that sufficient for nice vaping experience, in particular from the first puff.

[0023] A second aspect of the invention proposes an aerosol-generating system, which comprises the aerosol-generating device of the first invention aspect, and an article that comprises the aerosol-generating substrate and that is suitable for being accommodated in the chamber of the aerosol-generating device. When the aerosol-generating device is provided with the above- mentioned optical lens assembly, the article may be shaped so that, when it is accommodated in the chamber, the modifying of the beam cross-sectional area that is effective at the heating zone causes variation in a size of the heating zone within the article. Thus, article design can participate in reaching the best tradeoff about the size of the heating zone at the aerosol-generating substrate, for producing quickly enough aerosol amount without burning the substrate in the heating zone. To this purpose, the variation in the size of the heating zone within the article may cause varying an amount of the aerosol-generating substrate that is heated by the laser beam.

[0024] According to a possible design for the article, this latter may have a cavity shape at the heating zone, with a cross-sectional area of the cavity that decreases or is constant as a function of a depth in the cavity, and the cavity is open onto an exterior of the article. Then, the aerosol-generating system may be arranged so that the laser beam produced by the laser apparatus penetrates in the cavity parallel to a depth direction. With such arrangement of the aerosolgenerating system, the cavity of the article is preferably empty when the article is accommodated in the chamber of the aerosol-generating device. Put another way, an inner volume of the cavity of the article is preferably devoid of device component in at least a major part of this inner cavity volume, preferably in the whole inner cavity volume, in a configuration of the aerosol-generating system ready for delivering aerosol to a user. To this end, the aerosol-generating device is arranged so that insertion of the article into the chamber does not cause a component of the aerosol-generating device to penetrate or substantially penetrate the cavity of the article. In this way, heating of the aerosol-generating substrate by the laser beam is not hindered. In particular, the article may be a stick and the aerosol-generating substrate may comprise compressed tobacco.

[0025] A third aspect of the invention proposes a stick of compressed tobacco suitable to be used as an article in an aerosol-generating device, such stick of compressed tobacco being shaped to exhibit a cavity shape with a cross- sectional area of the cavity that decreases or is constant as a function of a depth in this cavity, the cavity being open onto the exterior of the stick. In particular, the cavity may be cone-shaped or cylinder-shaped.

[0026] According to a preferred design for loading the stick into the aerosolgenerating device, the cavity may be located at an end of the stick of compressed tobacco that is to be inserted first into the aerosol-generating device, through an insertion movement of the stick of compressed tobacco relative to the aerosolgenerating device which is parallel to a longitudinal direction of the stick of compressed tobacco.

[0027] The invention also proposes an aerosol-generating system that comprises an aerosol-generating device according to the first invention aspect, and a stick of compressed tobacco according to the third invention aspect, where the aerosol-generating device is arranged for accommodating the stick of compressed tobacco in its chamber.

[0028] A fourth aspect of the invention, which can be used in combination with the preceding aspects of the invention, or it is independent from the preceding aspects, proposes an aerosol-generating device for generating an aerosol from an aerosol-generating substrate, that comprises:

[0029] - a chamber for accommodating the aerosol-generating substrate, and

[0030] - a heater configured to heat the aerosol-generating substrate when present in the chamber, in order to generate the aerosol, the heater comprising an optical apparatus that comprises a light emitting element adapted for producing light suitable to generate heat in a portion of the aerosol-generating substrate, in which the optical apparatus further comprises a mirror assembly arranged for reflecting the light originating from the light emitting element toward the portion of the aerosol-generating substrate to be heated.

[0031] In particular, the mirror assembly may be combined with any type of the light emitting element, including laser emitting elements (e.g. the topological- cavity surface-emitting laser type according to the first aspect), light-emitting diodes, laser diodes, etc. In particular, the mirror assembly may have the advantages of facilitating the assembling of the optical apparatus into the aerosol-generating device, and preventing debris and dirt particles that originate from the article when in the chamber or dust from falling onto the optical output of the light emitting element.

[0032] This fourth aspect of the invention may be advantageously combined with one or more of the following optional additional features that can be provided separately or in combination of two or more of them:

[0033] - the optical apparatus may be arranged so that the mirror assembly deflects a center propagation direction of the light originating from the light emitting element with a deflection angle that is comprised between 80° and 100° (degree);

[0034] - the aerosol-generating device may have a proximal end from which a user of this aerosol-generating device inhales the aerosol, and a distal end opposed to the proximal end, with a longitudinal direction of the aerosolgenerating device oriented from the distal end to the proximal end, and the light emitting element may be secured within the aerosol-generating device so as to produce the light according to a center emission direction which is perpendicular to the longitudinal direction;

[0035] - the optical apparatus may be arranged so that a center propagation direction of the light as reflected by the mirror assembly is parallel to the longitudinal direction of the aerosol-generating device. In such case, the aerosol-generating device may further comprise an internal planar support, for example a printed circuit board, which is oriented parallel to the longitudinal direction of the aerosol-generating device, and the light emitting element may be fastened on the planar support, and may be of a type suitable for the center emission direction of the light as produced by this light emitting element to be perpendicular to the planar support; and

[0036] - the mirror assembly may comprise a reflecting stack, this reflecting stack comprising from a light-impinging side of the mirror assembly to a backside thereof: - an optional light polarizing coating;

[0037] - a glass plate, for example a plate of fused silica glass;

[0038] - a reflecting coating supported by the glass plate, preferably comprising at least one silver layer or aluminum layer, one or several dielectric layers, or a combination of at least one silver or aluminum layer with one or several dielectric layers; and

[0039] - a protecting coating, for example a polyvinyl butyral (PVB) coating.

[0040] - the mirror assembly may further comprise:

[0041] - an optional rigid mirror housing, advantageously of a material based on polyetheretherketone (PEEK), the mirror housing preferably having a light entrance face, a light exit face which is perpendicular to the light entrance face, and a supporting face which is slanted with respect to both light entrance face and light exit face, and the reflecting stack being bound to the supporting face; and

[0042] - at least one optional transparent plate disposed at the light entrance face or the light exit face of the mirror housing, or a right-angled transparent plate disposed at both light entrance face and light exit face of the mirror housing.

[0043] With such composition of the mirror assembly, the reflecting stack may be bound to the supporting face of the mirror housing through a silicone film, preferably a high-temperature silicone film. Independently from such binding means, the mirror housing, preferably its supporting face, may be provided with at least one cooling structure. This at least one cooling structure may comprise at least one through hole.

[0044] Further optional features of the fourth invention aspect are (it has to be noted that these optional additional features can be provided separately or in combination of two or more of them): - the optical apparatus may further comprise a lightguide located between the mirror assembly and the portion of the aerosolgenerated substrate to be heated, the lightguide being adapted for conducting the light produced by the light emitting element. Possibly, the light exit face of the mirror housing may be provided with a recess suitable for accommodating an end of the lightguide;

[0045] - the optical apparatus may further comprise an optical lens assembly arranged on a path of the light produced by the light emitting element, between this light emitting element and the mirror assembly. Such optical lens assembly may comprise two converging lenses and one diverging lens located between both converging lenses, and optionally may further comprise an actuator device arranged for modifying a position of the diverging lens between both converging lenses; and

[0046] - the heater may further comprise an auxiliary heating element that is separated from the optical apparatus and arranged for heating the aerosol-generating substrate in addition to the heat generated by the light produced by this optical apparatus.

[0047] A fifth aspect of the invention, which can be used in combination with the preceding aspects of the invention, or it is independent from the preceding aspects, proposes an aerosol-generating device for generating an aerosol from an aerosol-generating substrate, that comprises:

[0048] - a chamber for accommodating the aerosol-generating substrate, and

[0049] - a heater configured to heat the aerosol-generating substrate when present in the chamber, in order to generate the aerosol, the heater comprising an optical apparatus that comprises a light emitting element adapted for producing light suitable to generate heat in a portion of the aerosol-generating substrate, in which the optical apparatus further comprises an optical lens assembly which is arranged on the path of the lightfrom the light emitting element to the heating zone.

[0050] In particular, the optical lens assembly may be combined with any type of the light emitting element, including laser emitting elements (e.g. the topological-cavity surface-emitting laser type according to the first aspect), lightemitting diodes, laser diodes, etc.

[0051] In particular, the optical lens assembly being designed for modifying a beam cross-sectional area of the laser beam that is effective at the heating zone. Such optical lens assembly allows setting a trade-off about the size of the heating zone at the aerosol-generating substrate, for producing quickly sufficient aerosol amount without burning the substrate in the heating zone.

[0052] This fifth aspect of the invention may be advantageously combined with one or more of the following optional additional features that can be provided separately or in combination of two or more of them:

[0053] - the optical lens assembly may comprise two converging lenses and one diverging lens, the diverging lens being located between both converging lenses

[0054] - the optical lens assembly may further comprise an actuator device which is arranged for modifying a position of the diverging lens between both converging lenses, thereby modifying the beam cross- sectional area that is effective at the heating zone, depending on the position of the diverging lens

[0055] - preferably, the optical lens assembly may be located between the light emitting element and a mirror device. Such location for the optical lens assembly avoids that debris and dirt particles that originate from the article when in the chamber fall onto the optical lens assembly.

[0056] The lens assembly according to the fifth aspect can be combined with a mirror assembly, e.g. the mirror assembly according to the fourth aspect, the mirror assembly being arranged for reflecting the light originating from the light emitting element toward the portion of the aerosol-generating substrate to be heated.

[0057] Further optional features of the fifth invention aspect are (it has to be noted that these optional additional features can be provided separately or in combination of two or more of them):

[0058] - the optical apparatus may further comprise a lightguide located between the mirror assembly and the portion of the aerosol-generated substrate to be heated, the lightguide being adapted for conducting the light produced by the light emitting element. Possibly, the light exit face of the mirror housing may be provided with a recess suitable for accommodating an end of the lightguide;

[0059] - the heater may further comprise an auxiliary heating element that is separated from the optical apparatus and arranged for heating the aerosol-generating substrate in addition to the heat generated by the light produced by this optical apparatus.

[0060] These and other features of the invention will be now described with reference to the appended figures, which relate to preferred but not-limiting embodiments of the invention.

[0061] - BRIEF DESCRIPTION OF THE DRAWINGS -

[0062] Figure 1 shows an aerosol-generating device according to a possible embodiment of the present invention.

[0063] Figure 2 shows an article according to an embodiment of the present invention, which is to be used in combination with the aerosol-generating device of Figure 1 .

[0064] Figure 3 shows an assembly internal to the aerosol-generating device of Figure 1 , after introduction of the article of Figure 2 into said aerosol-generating device.

[0065] Figure 4 is an enlargement of part of Figure 3, focused on a laser apparatus which is comprised in the aerosol-generating device. Figure 5 is an exploded view of the laser apparatus of Figure 4 or of an optical apparatus used in an aerosol-generating device according to the invention.

[0066] For clarity sake, element sizes which appear in these figures do not correspond to actual dimensions or dimension ratios. Also, same reference numbers or reference signs which are indicated in different ones of these figures denote identical elements of elements with identical function.

[0067] - DETAILED DESCRIPTION OF THE INVENTION -

[0068] Referring to Figure 1 , an aerosol-generating device 1 may have a general elongated shape parallel to a longitudinal direction L. It extends between a proximal end PE and a distal end DE, and the longitudinal direction L is oriented from the distal end DE toward the proximal end PE. The aerosol-generating device 1 is enclosed within a casing 100. The use position of the aerosolgenerating device 1 when a user thereof inhales aerosol from the proximal end PE corresponds to the longitudinal direction L oriented substantially vertically upward, so that gravity is directed opposite the longitudinal direction L. It is possible, but not necessarily, that the casing 100 is to be provided with a mouthpiece (not represented) at the proximal end PE for the user to inhale aerosol therethrough. In particular, no mouthpiece may be used when an article that contains some aerosol-generating substrate is designed so as to partially extend out of the casing 100 when loaded into the device 1. It may be so for example when the article is shaped as a stick as described here. Reference number 101 denotes a battery internal to the device 1 , and reference sign CH denotes a chamber designed for accommodating an article within the device 1. In the embodiment described here but not limitedly, the chamber CH is shaped as a hollow cylinder parallel to the longitudinal direction L and opens onto the exterior of the casing 100 at the proximal end PE of the device 1. Optionally, the chamber CH may be formed by a tubular oven 95 which is connected to be supplied with electrical power from the battery 101 . Such optional oven forms an auxiliary heating element as mentioned in the general part of the present description. However, the present invention may be combined with other known technology for implementing an auxiliary heating element. For example, the auxiliary heating element may be provided at or in proximity of a sidewall of the chamber CH. The chamber CH may be designed for accommodating an article as shown in Figure 2. This article may be shaped as a stick 2 which extends longitudinally between first stick end E1 and second stick end E2. Aerosolgenerating substrate 3, for example of compressed tobacco in the example described here, is contained in the stick 2 at least at its first end E1. However, the invention can be implemented with any type and structure of the aerosolgenerating substrate, including solid substrate, foam- or mousse-based substrate, etc. The chamber CH and the stick 2 are sized with respective diameters so that the stick 2 can slide in the chamber CH and thus can be introduced by a user into the chamber CH through its opening at the proximal end PE of the device 1 . The stick 2 is to be introduced into the chamber CH with its end E1 first, so that the aerosol-generating substrate 3 is facing the bottom of the chamber CH.

[0069] In preferred embodiments of the invention, the stick 2 may be provided with a cavity C at its end E1 , this cavity C opening at the end face of the stick 2 so that the cavity C faces the bottom of the chamber CH when the stick 2 is within this chamber CH. The cavity C may be shaped as a cone or cylinder with cone / cylinder axis parallel to the longitudinal direction of the stick 2. In case of cone-shaped cavity C, the cavity cross-sectional area decreases when moving from the stick end E1 toward the stick end E2. DD denotes the depth direction of the cavity C from the stick end E1 toward the interior of the cavity C. When the cavity C is cone-shaped, the cone shape is oriented so that the cross-sectional area of the cavity C perpendicular to the depth direction DD decreases when moving according to oriented depth direction DD. Such cavity C can be easily provided using a sliding tool that is partially driven into the stick 2 from its end E1 to compress part of the tobacco.

[0070] The chamber CH of the aerosol-generating device 1 is preferably devoid of any component or structure that would penetrate the cavity C when the stick 2 is introduced into the chamber CH. Thus, the cavity C is empty in a configuration where the stick 2 has been inserted into the chamber CH up to a position of the article 2 within the chamber CH that allows aerosol generation and delivery to a user.

[0071] The aerosol-generating device 1 is equipped with a heater 4 for generating the aerosol from the aerosol-generating substrate 3 when the stick 2 is appropriately within the chamber CH. To this purpose, the heater 4 comprises a laser apparatus 85 (see Figure 3) which is designed for irradiating the substrate 3 in order to heat this latter. This laser apparatus 85 may be combined with the above-mentioned auxiliary heating element 95 but it may also be implemented alternatively without auxiliary heating element.

[0072] According to the invention, the laser apparatus 85 is based on a laser emitting element 5 that is of TCSEL-type, standing for topological-cavity surfaceemitting laser, for example such as described in the article entitled “Topological- cavity surface-emitting laser” de L. Yang et al., Nature Photonics, Letters, https: / / doi.Org / 10.1038 / S41566-022-00972-6 According to an embodiment of the present invention, the TCSEL-type laser emitting element s exhibits single-mode operation and may have a Dirac vortex pattern. It produces a laser beam 6 with a center emission direction that is perpendicular to a semiconductor substrate of the light-emitting element 5. In a usual way, center emission direction denotes the mean propagation direction of the laser beam 6 as produced by the light emitting element 5, although this laser beam may spread angularly from this mean emission direction, corresponding to its divergence angle. When of TCSEL-type, the light emitting element 5 can have an optical continuous output power of one or several watts, an optical output area of more than 500 pm (micrometer) x 500 pm and a beam divergence of less than 1 ° (degree) x 1 °. Compared to other laser sources, the much higher values for the optical continuous output power and optical output area in the TCSEL-type case, and the much narrower beam divergence allow to reach the advantages mentioned in the general part of the present description for the aerosol-generating device 1 . In addition, the TCSEL-type light emitting element 5 may have a wavelength value of about 1550 nm (nanometer) which suits for heating the aerosolgenerating substrate 3 from a location thereof where the laser beam 6 impinges onto this substrate 3. Internally to the aerosol-generating device 1 , the TCSEL-type light emitting element 5 may be secured to a planar support 50, for example of PCB- type with PCB standing for printed circuit board, which is parallel to the longitudinal direction L. Then the center emission direction ED of the TCSEL- type light emitting element 5 is perpendicular to the longitudinal direction L as shown in Figure 4. A mirror device 9 with 45°-orientation relative to the longitudinal direction L may be used so that a center propagation direction PD of the baser beam 6 is parallel to the longitudinal direction L downstream from the mirror device 9 and propagates toward the chamber CH. The mirror device 9 may have a structure as described later below with reference to Figure 5. Thus, the laser beam 6 impinges on the end E1 of the stick 2, partially or totally within the cavity C. The area of the aerosol-generating substrate 3 that is irradiated by the laser beam 6 is denoted HZ, standing for heating zone, in Figures 1 and 3. The heating zone HZ extends at the end E1 of the stick 2, in and possibly also around the cavity C if any, depending on the cross-sectional area of the laser beam 6 at this location. In particular, the heating zone HZ may extend on a limited portion of the bottom face of the cavity C, or on this whole cavity bottom face and also a limited portion of the sidewall of the cavity C, or also possibly on the whole cavity bottom face and sidewall and also on the cavity-surrounding end face of the stick 2.

[0073] A lightguide 8 may be arranged between the mirror device 9 and the chamber CH. Such lightguide 8 may be a one-piece element of a material transparent to the laser beam 6, for example of cylindrical shape, which is metallized on its lateral peripheral surface.

[0074] The light-emitting element 5, the optional mirror device 9, the optional lightguide 8 and an optional lens assembly 10 form together the laser apparatus 85.

[0075] When implemented, the lens assembly 10 has the function of varying the cross-sectional area of the laser beam 6 at the end E1 of the stick 2, thereby varying the size of the heating zone HZ. It may be located on the path segment of the laser beam 6 between the light emitting element 5 and the mirror device 9. It is possible to adjust the lens assembly 10 so that the laser beam 6 is focused onto a small heating zone HZ, thereby allowing higher temperature to be reached for generating sufficient aerosol amount. Simultaneously, the lens assembly 10 is also adjusted for the heating zone HZ not to be too small. In this way, excessive heating temperature that could cause burning of the aerosol-generating substrate 3 is avoided.

[0076] The lens assembly 10 if any may comprise two converging lenses 11 and 13, and a diverging lens 12 which is arranged between both lenses 11 and 13 along the center emission direction ED (see Figure 4). Each of the lens 11 and 13 may be a plano-convex lens or a biconvex lens. The lens 12 may be a biconcave lens and it may be mounted on an actuator device 14 suitable for translating the lens 12 between both lenses 11 and 13. For example, the actuator device 14 may comprise a permanent magnet ring secured to the peripheral edge of the lens 12, and further comprise an electrically-controlled coil translator with surrounds the magnet ring and is suitable for moving the lens 12 to any position from a first location next to the lens 11 to a second location next to the lens 13. Obviously, other technologies may be used alternatively for the actuator device 14. Control of the actuator device 14 for placing the lens 12 next to the lens 11 makes the laser beam 6 be narrow at the end E1 of the stick 2, thereby producing higher heating temperature for the aerosol-generating substrate 3 in the heating zone HZ. Conversely, control of the actuator device 14 for placing the lens 12 next to the lens 13 as shown in Figure 4 makes the heating zone HZ be larger, thereby allowing heating of new portions of the substrate 3 but with reduced heating power density.

[0077] A further advantage of the configuration that has just been described for the aerosol-generating device 1 is now indicated. It is possible that dust, dirt particles and / or debris including tobacco debris fall to the bottom of the chamber CH, when the device 1 is oriented with its longitudinal direction L upward. Such undesired particles may diffuse or absorb part of the laser beam 6 before it impinges on the aerosol-generating substrate 3, causing heating power losses and increase in the heating time as a consequence. Implementing the lightguide 8 as described avoids that the undesired particles reach the mirror device 9. The lateral offset of the light emitting element 5 that is provided by the 45°-oriented mirror device 9 also participates in avoiding that the undesired particles deposit on the light emitting element 5 and / or the lens assembly 10. Possibly, the lightguide 8 can be extracted through the chamber CH for cleaning. This ensures longer lifetime to the aerosol-generating device 1 .

[0078] The mirror device 9 may be provided in the form of a mirror assembly as shown in Figure 5.

[0079] The mirror operation may be provided by a reflecting stack formed by a reflecting coating 93 deposited on a glass plate 92. The glass plate 93 may be of fused silica for low light-absorption if light from the light emitting element 5 is to impinge on the reflecting coating 93 through the glass plate 92. The reflecting coating 93 may be multilayered, in particular including a silver layer or an aluminium layer, or a stack of several dielectric layers, or a combination of at least one metal layer and at least one dielectric layer. The reflecting stack also includes a protecting coating 94 that covers the reflecting coating 93 on a side thereof opposite the glass plate 92.

[0080] Such reflecting stack may be secured in a rigid mirror housing 96 according to a 45°-angle relative to the center emission direction ED of the light emitting element 5 and also relative to the longitudinal direction L of the aerosolgenerating device 1. To this end, the mirror housing 96 may be provided with a light entrance face 961 which is perpendicular to the center emission direction ED of the light emitting element 5, a light exit face 962 which is perpendicular to the longitudinal direction L and thus also perpendicular to the center propagation direction PD, and a supporting face 963 which is 45°-angled with respect to both light entrance face 961 and light exit face 962. Then, the reflecting stack may be glued to the supporting face 963 internally to the mirror housing 96, by adhering the protecting coating 94 to the supporting face 963. Adhesion may be produced by an intermediate silicone film 95, or any other binding material. High- temperature silicone may be preferred for avoiding ageing of the binding material. Preferably, one or several through hole(s) 960 may be provided in the supporting face 963, and also through the silicone film 95, as a cooling structure for avoiding that the reflecting stack and the binding material warm up due to residual light-absorption in the glass plate 92 and in the reflecting coating 93. Possibly, a light-polarization coating 91 may be arranged on the glass plate 92, on a side thereof opposite the reflecting coating 93. The lightpolarization coating 91 may be designed for reducing polarization in the beam that is reflected toward the aerosol-generating substrate 3.

[0081] Advantageously, a transparent plate 97 may be provided at the light entrance face 961 , and another one at the light exit face 962. Preferably, a right- angled transparent plate may be implemented for fitting both light entrance face 961 and light exit face 962 with a single assembly operation.

[0082] The mirror housing 96 may be of PEEK-based material, PEEK standing for polyetheretherketone which is deemed thermally resistant.

[0083] Advantageously again, the light exit face 962 of the mirror housing 96 may be provided with a peripheral ledge 964 which forms a central recess adapted for accommodating an end of the lightguide 8. This facilitates correct repositioning the lightguide 8 after removal thereof through the chamber CH, for example for cleaning purpose.

[0084] It should be understood that implementing a mirror assembly in an aerosol-generating device according to the invention is not limited to the mirror assembly design that has just been described with reference to Figure 5.

[0085] It should also be understood that implementing any mirror assembly within an aerosol-generating device forms an invention separate from the type of the light emitting element, this latter being of topological-cavity surface-emitting laser type or not. More generally, the mirror assembly may be implemented in the aerosol-generating device whatever the type of the light emitting element, of laser type or of any non-laser type.

[0086] It should also be understood that implementing any lens assembly within an aerosol-generating device forms an invention separate from the type of the light emitting element, this latter being of topological-cavity surface-emitting laser type or not. More generally, the lens assembly may be implemented in the aerosol-generating device whatever the type of the light emitting element, of laser type or of any non-laser type.

Claims

C L A I M S1. An aerosol-generating device (1) for generating an aerosol from an aerosol-generating substrate (3), comprising:- a chamber (CH) for accommodating the aerosol-generating substrate (3); and- a heater (4) configured to heat the aerosol-generating substrate (3) when present in the chamber (CH), in order to generate the aerosol, the heater comprising a laser apparatus (85) that comprises a laser emitting element (5) suitable for producing a laser beam (6) configured to generate heat in a heating zone (HZ) of said aerosol-generating substrate, wherein the laser emitting element (5) is of a topological-cavity surface-emitting laser type.

2. The aerosol-generating device (1) according to claim 1 , wherein the laser apparatus (85) further comprises a mirror device (9) arranged so that a center emission direction (ED) of the laser emitting element (5) is perpendicular to a center propagation direction (PD) of the laser beam (6) towards the heating zone (HZ).

3. The aerosol-generating device (1) according to claim 1 or 2, wherein the laser apparatus (85) further comprises an optical lens assembly (10) arranged on a path of the laser beam (6) from the laser emitting element (5) to the heating zone (HZ), said optical lens assembly being designed for modifying a beam cross-sectional area of the laser beam that is effective at said heating zone.

4. The aerosol-generating device (1) according to claim 3, wherein the optical lens assembly (10) comprises two converging lenses (11 , 13) and one diverging lens (12), the diverging lens being located between both converging lenses.

5. The aerosol-generating device (1) according to claim 4, wherein the optical lens assembly (10) further comprises an actuator device (14) arranged for modifying a position of the diverging lens (12) between both converging lenses (11 , 13), thereby modifying the beam cross-sectional area that is effective at the heating zone (HZ), depending on the position of the diverging lens.

6. The aerosol-generating device (1) according to claim 2 and one of claims 3 to 5, wherein the optical lens assembly (10) is located between the laser emitting element (5) and the mirror device (9).

7. The aerosol-generating device (1) according to claim 2 and optionally one of claims 3 to 6, wherein the laser apparatus (85) further comprises a lightguide (8) located between the mirror device (9) and the heating zone (HZ).

8. The aerosol-generating device (1 ) according to one of the preceding claims, having a proximal end (PE) from which a user of said aerosol-generating device inhales the aerosol, and a distal end (DE) opposed to the proximal end, wherein the heating zone (HZ) is located between the laser apparatus (85) and the proximal end along a longitudinal direction (L) oriented from said distal end to said proximal end, and wherein the heating zone is located within the chamber (CH) at an end of said chamber opposed to said proximal end of the aerosolgenerating device.

9. The aerosol-generating device (1 ) according to one of the preceding claims, wherein the heater (4) further comprises an auxiliary heating element (95) that is separated from the laser apparatus (85) and arranged for heating the aerosol-generating substrate (3) at least in the heating zone (HZ) in addition to the heat generated by the laser beam (6).

10. An aerosol-generating system, comprising the aerosol-generating device (1 ) according to one of the preceding claims, and an article that comprises the aerosol-generating substrate (3) and that is suitable for being accommodated in the chamber (CH) of said aerosol-generating device.

11. The aerosol-generating system according to claim 10, wherein the aerosol-generating device (1) meets claim 3, and wherein the article is shaped so that, when said article is accommodated in the chamber (CH), the modifying of the beam cross-sectional area that is effective at the heating zone (HZ) causes variation in a size of said heating zone within the article.

12. The aerosol-generating system according to claim 11 , wherein the variation in the size of the heating zone (HZ) within the article causes varying an amount of the aerosol-generating substrate (3) that is heated by the laser beam (6).

13. The aerosol-generating system according to claim 11 or 12, wherein the article has a cavity shape at the heating zone (HZ), with a cross-sectional area of the cavity (C) that decreases or is constant as a function of a depth in the cavity, and the cavity is open onto an exterior of the article, and said aerosolgenerating system is arranged so that the laser beam (6) produced by the laser apparatus (85) penetrates in the cavity parallel to a depth direction (DD).

14. The aerosol-generating system according to one of claims 10 to 13, wherein the article is a stick (2) and the aerosol-generating substrate (3) comprises compressed tobacco.

15. A stick (2) of compressed tobacco suitable to be used as an article in an aerosol-generating device (1), the stick of compressed tobacco being shaped to exhibit a cavity shape with a cross-sectional area of the cavity (C) that decreases or is constant as a function of a depth in said cavity, said cavity being open onto an exterior of the stick.

16. The stick (2) of compressed tobacco according to claim 15, wherein the cavity (C) is cone-shaped or cylinder-shaped.

17. The stick (2) of compressed tobacco according to claim 15 or 16, wherein the cavity (C) is located at an end (E1 ) of the stick of compressed tobacco that is to be inserted first into the aerosol-generating device (1), through an insertion movement of said stick of compressed tobacco relative to saidaerosol-generating device which is parallel to a longitudinal direction of said stick of compressed tobacco.

Images