Optical Processing Device

Abstract

According to one aspect, a processing device 2, 30, 60, 130 is provided for performing a light-based processing operation on or with an object. The processing device 2, 30, 60, 130 includes a light source 12 for generating light for performing a processing operation, and a dichroic filter 34;64;104;134 arranged at a first angle with respect to the incident light, such that the incident light is separated into a transmitted light component and a reflected light component based on a cutoff wavelength of the dichroic filter 34;64;104;134, the transmitted light component being transmitted through the dichroic filter 34;64;104;134 and the reflected light component being separated through the dichroic filter 34;64;104;134. The light exit window 10 includes a dichroic filter 34;64;104;134, the light component being reflected by the dichroic filter 34;64;104;134, a light exit window 10 through which the light component leaves the processing device 2;30;60;130, a beam dump 44;74;140 configured to absorb the light component, and a heat sink 46;76;142 coupled to the beam dump 44;74;140 for dissipating heat from the beam dump 44;74;140. The light exit window 10 and the beam dump 44;74;140 are positioned relative to the dichroic filter 34;64;104;134, such that one of the transmitted and reflected light components leaves the processing device 2;30;60;130 through the light exit window 10, and the other of the transmitted and reflected light components enters the beam dump 44;74;140. The dichroic filters 34; 64; 104; 134 are provided on a first face of the solid dichroic prism 38; 68 or on an inner surface of a solid dichroic cuboid.

Description

[Technical field]

[0001] This application relates to processing devices for performing light-based processing operations on or to an object. [Background technology]

[0002] Hair removal techniques include shaving, electrolysis, plucking, laser and light therapy (known as photoepilation), and therapeutic antiandrogen injections. Light-based techniques are also used in other types of dermatological treatments, such as skin rejuvenation and acne treatment.

[0003] Light-based hair treatment inhibits hair growth by exposing the skin to bright flashes or pulses of light (in the case of non-coherent light sources) known as Intense Pulsed Light (IPL). Through the use of the appropriate configuration of light energy, i.e. wavelength, intensity and / or pulse duration (in the case of light pulsed), selective heating of the hair root and subsequent temporary or permanent damage to the hair follicle can be achieved. IPL can be produced by a high intensity light source such as a gas discharge lamp (e.g., a xenon flash lamp). The light penetrates the skin and is absorbed at the hair root, particularly by the melanin pigment. This results in an increase in the temperature of the hair root and subsequently in the surrounding tissue. The heat generated damages the hair follicle and, if the temperature increase is sufficient, hair growth is inhibited. This process is known as photothermolysis. When treatments are repeated at intervals of 2 to 4 weeks, long-lasting hair reduction is achieved.

[0004] The main optical elements of a typical IPL device's optical arrangement are a light source, such as a flashlamp, a concave back reflector, a side reflector, and an absorbing filter. The flashlamp emits light in all directions. The back reflector and the side reflector form a reflective cavity around the lamp, which directs the light towards the skin (i.e., the reflective cavity can collimate the light emitted by the lamp). Xenon flashlamps can be used. Since these lamps have a broad emission spectrum, the IPL device can have a long-pass absorbing filter with a cutoff between 500-600 nanometers (nm), preventing shorter wavelengths of light from reaching the skin. These shorter wavelengths are usually absorbed by hemoglobin in the blood, which would otherwise cause discomfort and side effects in the subject, while the longer wavelengths of light are passed by the filter and enter the subject, where the photothermolysis process of the skin / hair takes place. Summary of the Invention [Problem to be solved by the invention]

[0005] Due to the absorption of unwanted light (light with short wavelengths), the absorbing filter heats up. When the IPL device is turned on for a long period of time at a high repetition rate, the absorbing filter gradually increases in temperature and may reach a temperature of over 200°C. This high temperature is perceived as uncomfortable by the subject or device user due to the radiant heat passing through the opening (light exit window) to the skin and the opening material itself becoming too hot to touch. Furthermore, the filter may exceed a safe touch temperature. This may be problematic because the filter may be exposed to the user when the attachment is replaced or cleaned. Furthermore, the cutoff wavelength may shift as a function of the filter temperature.

[0006] As an alternative to using an absorbing filter to separate light into treatment light (i.e., light that performs a hair removal operation) and unwanted light (e.g., light of shorter wavelengths), the absorbing filter can be replaced with a dichroic filter, such as a long-pass dichroic reflective filter or a short-pass dichroic reflective filter. However, in this case, the unwanted light can still be present in the treatment device and "reflect" inside the treatment device, which can damage the elements, and the unwanted light can also exit the treatment device through the light exit window. In these arrangements, the dichroic filter acts as a primary separator to separate the generated light into treatment light and unwanted light, while an absorbing filter can be provided at or near the light exit window to absorb "stray" unwanted light exiting the treatment device. However, if much of the unwanted light separated by the dichroic filter is reflected inside the treatment device, the absorbing filter will absorb a lot of light, which will result in the heating problem described above.

[0007] For example, most of the light reflected by the dichroic filter can find its way back to the absorbing filter via multiple reflections in the reflective cavity surrounding the lamp until it is incident on the dichroic filter at a large angle. At large angles, the dichroic filter will inevitably leak and transmit its component light to the absorbing filter. Through this recycling process, a significant portion of the energy on the short wavelength side of the spectrum is absorbed by the absorbing filter, which heats it up. Additionally, some energy is transferred to the lamp, which is undesirable because it can have a negative effect on the lamp's life.

[0008] Therefore, additional solutions regarding the optical arrangement of processing equipment are desired to address the heating problem.

[0009] US5782895A discloses an illuminator for photodynamic therapy that includes a light bulb, a heat sink, and a filter assembly. The filter assembly includes the following elements in the optical path: a high-pass filter for filtering light having a wavelength equal to or less than a first wavelength, a low-pass dichroic filter for filtering light having a wavelength equal to or greater than a second wavelength, and a dichroic mirror for reflecting light having a wavelength between the first and second wavelengths. Light transmitted through the dichroic mirror is directed to a heat sink.

[0010] In the illumination system of US2011 / 0051216A1, light generated by a light source is focused and collimated by a dichroic beam splitter, which transmits the light to the object and reflects the unwanted energy towards a heat trap 48 for dissipation.

[0011] US6413268B1 discloses a UV phototherapy device that includes a UV arc lamp, the light of which is directed through a dichroic mirror to a treatment handpiece or a fan and heat sink assembly.

[0012] US4048490A discloses a dichroic filter system for providing UV light, where the UV light is directed towards a work piece and unwanted IR light is absorbed by a dichroic filter and absorber arrangement, the absorber further comprising a heat sink. [Means for solving the problem]

[0013] According to a first specific aspect, there is provided a processing device for performing a light-based processing operation on or with respect to an object, the processing device comprising: a light source generating light for performing the processing operation; a dichroic filter disposed at a first angle with respect to an incident light, the incident light being separated into a transmitted light component and a reflected light component based on a cutoff wavelength of the dichroic filter, the transmitted light component being transmitted through the dichroic filter and the reflected light component being reflected by the dichroic filter; a light exit window disposed relative to the dichroic filter, one of the transmitted light component and the reflected light component being emitted from the processing device through the light exit window; a beam dump configured and disposed relative to the dichroic filter, the other of the transmitted light component and the reflected light component being incident on the beam dump and absorbed by the beam dump; and a heat sink coupled to the beam dump for dissipating heat from the beam dump. In a first embodiment, the dichroic filter is provided on the surface of a solid dichroic prism or on the surface of a solid dichroic cuboid. The solid guides the incident light from the light source to the object, and the dichroic separation of the incident beam takes place in this solid medium. In the case of a solid light guide, the light incident at a correct angular range is trapped inside the guide by total internal reflection. Once trapped, the light remains inside the guide until it encounters an interface below the TIR critical angle, for example. Thus, the first embodiment provides that the unwanted light components are directed to the beam dump where they are absorbed, and the heat generated in the beam dump due to the absorption of light is dissipated through the coupled heat sink. This reduces the heat buildup in the processing device, thereby improving the user experience when working with the processing device. At the same time, the combination of the solid medium and the dichroic filter provides a more effective confinement of the processing light (i.e., minimization of path loss) while transmitting the desired wavelengths to the object.

[0014] These and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an illustration of an exemplary processing device. [Diagram 2] FIG. 2 is an illustration of a portion of a processing apparatus according to a first set of embodiments. [Diagram 3] FIG. 2 is an illustration of a portion of a processing apparatus according to a second set of embodiments. [Figure 4a] FIG. 1 illustrates some exemplary dichroic filter and prism configurations. [Figure 4b] FIG. 1 illustrates some exemplary dichroic filter and prism configurations. [Diagram 5] FIG. 11 is an illustration of a portion of a processing apparatus according to a third set of embodiments. [Figure 6] FIG. 11 is an illustration of a portion of a processing apparatus according to a fourth set of embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Exemplary embodiments will now be described, by way of example only, with reference to the following drawings, in which:

[0017] FIG. 1 is an illustration of an exemplary processing device 2 that can be used to apply light pulses to an area of ​​skin. It should be understood that the processing device 2 of FIG. 1 is presented only as an example of a handheld processing device 2 with which the present invention can be used, and that the processing device 2 is not limited to the form shown in FIG. 1 or to being a handheld processing device. The processing device 2 is for use on the body of a subject (e.g., a human or animal) and is held in one or both hands of a user during use. The processing device 2 performs some treatment operation on the hair and / or skin of the subject's body using light when the processing device 2 is in close proximity to or in contact with a body part of the subject. Treatment operations include hair removal by light therapy (known as photoepilation treatment or intense pulsed light treatment). Treatment operations also include skin rejuvenation. Such treatments can be performed using pulses of light, or by applying light continuously or for extended periods of time.

[0018] As described herein, the processing device 2 is operated or used by a "user" and the processing device 2 is used on the body of a "subject." In some cases, the user and the subject are the same person, i.e., the processing device 2 is held in the hand and used by the user on himself (e.g., on the skin of the leg). In other cases, the user and the subject are different people, e.g., the processing device 2 is held in the hand and used by the user on another person.

[0019] The exemplary treatment device 2 has a housing 4 including at least a handle portion 5 and a head portion 6. The handle portion 5 is shaped to allow a user to hold the treatment device 2 in one hand. The head portion 6 is at a head end 8 of the housing 4 and is positioned to contact the subject's body or skin such that a treatment operation is performed on the subject's body or skin where the head portion 6 contacts the subject's body or skin.

[0020] The treatment device 2 is for performing a treatment operation using light, such as light pulses. Thus, in FIG. 1, the head portion 6 has a light exit window 10, also called an opening or treatment window, which is arranged in or on the housing 4, so that the light exit window 10 can be arranged adjacent to or on (e.g. in contact with) the skin of the subject. The treatment device 2 includes a light source 12 (not directly visible in FIG. 1) for generating light that is applied to the skin of the subject through the light exit window 10 to perform a treatment operation. The light source 12 is arranged in the housing 4, so that light pulses are provided from the light source 12 through the light exit window 10. The opening / light exit window 10 may be in the form of an opening provided in the head end 8 of the housing 4, or it may be in the form of a window (including a waveguide) that is transparent or semi-transparent to the light (i.e. light can pass through the window).

[0021] In the exemplary embodiment shown in Fig. 1, the light exit window 10 has a generally rectangular shape, which results in a generally rectangular shaped skin treatment area (also referred to herein as treatment area) on the skin. It should be understood that the light exit window 10 can have any other desired shape. For example, the light exit window 10 can be a square, an ellipse, a circle, or any other polygonal shape.

[0022] Light source 12 may generate light pulses of any suitable or desired wavelength (or range of wavelengths) and / or intensity. For example, light source 12 may generate visible light, infrared (IR) light, and / or ultraviolet (UV) light. Light source 12 may include any suitable type of light source, such as a gas discharge lamp, one or more light emitting diodes (LEDs), one or more lasers, etc.

[0023] The light source may be a gas discharge lamp. A gas discharge lamp may have a gas within a housing (e.g., a tube), where the gas is typically a noble gas such as xenon, argon, or krypton, or a mixture of such gases. The gas discharge lamp may also be a flash lamp, e.g., a xenon flash lamp.

[0024] The light source 12 can provide light pulses with spectral content in the range of 560-1200 nanometers (nm) for a duration of approximately 2 milliseconds (ms), because these wavelengths heat the melanin in the hair and hair roots through absorption, which puts the hair follicle into telogen phase and prevents hair growth, while absorption by other chromophores in the skin (e.g., hemoglobin, water) is limited.

[0025] The light source 12 can be configured to provide pulsed or continuous light. That is, the light source 12 can be configured to generate light at high intensity for a short duration (e.g., less than 1 second). The intensity of the light should be high enough to perform a treatment operation on the skin or body part adjacent to the light exit window 10.

[0026] The illustrated processing device 2 also includes two skin contact sensors 14, 16 located on or within the head portion 6 that are used to determine whether the head portion 6 is in contact with the skin before light is generated to avoid directing light into the user's or subject's eyes.

[0027] The illustrated processing device 2 also includes user controls 18 that may be manipulated by a user to cause the head portion 6 to activate the processing device 2 to perform a required processing operation on the subject's body (e.g., generation of one or more light pulses by the light source 12). The user controls 18 may be in the form of a switch, button, touch pad, etc. The user controls 18 may also be used to switch between different processing operations or between different settings for those processing operations.

[0028] As discussed above, dichroic filters can be used in the optical configuration of a processing device to separate the relatively broad spectrum light generated by a light source into treatment light (i.e., light used to perform a hair removal operation or other skin / hair treatment) and unwanted light (i.e., light that is not suitable for performing a treatment operation and / or is harmful to the subject). However, a need still exists to address unwanted light that is present in the processing device.

[0029] In accordance with the techniques described herein, a beam dump is provided within the processing device to absorb unwanted light, and a heat sink coupled to the beam dump is provided to dissipate heat from the beam dump.

[0030] According to certain embodiments, a processing device is provided for performing a light-based processing operation on or on an object, such as hair removal, photoepilation, etc. The processing device includes a light source generating light for performing the processing operation, and a dichroic filter arranged at a first angle with respect to the light incident from the light source, such that the incident light is separated into a transmitted light component and a reflected light component based on the cutoff wavelength of the dichroic filter (note that in practice, the cutoff wavelength is generally not a sharp cutoff but has a transition over a finite wavelength width). The transmitted light component is the component of the generated light that is transmitted through the dichroic filter, and the reflected light component is the component of the generated light that is reflected by the dichroic filter. The processing device includes a light exit window through which one of the light components is emitted from the processing device to perform the processing operation on the object. The light exit window and the beam dump are positioned relative to the dichroic filter, so that one of the transmitted and reflected light components leaves the processing device through the light exit window, and the other of the transmitted and reflected light components enters the beam dump. In other words, one of the transmitted and reflected light components leaves the processing device through the light exit window. The other of the transmitted and reflected light components enters the beam dump and is absorbed by the beam dump. Thus, in both configurations, the unwanted light components are directed to the beam dump and absorbed there, and the heat generated in the beam dump due to the absorption of light is dissipated via the coupled heat sink. This reduces the build-up of heat in the processing device, thereby improving the user experience when handling the processing device.

[0031] Two alternative configurations of the dichroic filter, the light exit window and the beam dump are primarily envisaged herein. In a first configuration, described with reference to Fig. 2, the dichroic filter is configured such that the transmitted light component is the component of light that performs the processing operation and the transmitted light component leaves the processing device via the light exit window. The reflected light component enters the beam dump and is received by the beam dump. In a second configuration, described with reference to Fig. 3, the dichroic filter is configured such that the reflected light component is the component of light that performs the processing operation and the reflected light component leaves the processing device via the light exit window. The transmitted light component enters the beam dump and is received by the beam dump.

[0032] As used herein, the term "processing light" refers to the light component of the generated light that is used to perform a processing operation and is intended to exit the processing device through a light exit window. The term "unwanted light" refers to the light component of the generated light that is not used to perform a processing operation (e.g., because the light does not have the appropriate wavelength and / or because the light has an undesirable effect on the target) and is intended to be absorbed by the beam dump.

[0033] In some embodiments, also shown in Figures 2 and 3, in addition to the dichroic filter, the processing device may also have an absorbing filter disposed relative to the dichroic filter and the light exit window, such that processing light emitted from the processing device through the light exit window passes through the absorbing filter. The absorbing filter is configured to absorb unwanted light when the unwanted light reaches the light exit window (i.e., the absorbing filter is configured to absorb light having a wavelength corresponding to the unwanted light).

[0034] Accordingly, Figure 2 is an illustration of a portion of a processing apparatus 30 according to a first set of embodiments. Processing apparatus 30 has a light source 12 disposed within a cavity housing 32 of processing apparatus 30. Light source 12 can be controllable or configured to generate pulses of light (e.g. IPL), or continuous light, or relatively continuous light.

[0035] The cavity housing 32 forms a reflective cavity for the light source 12 such that the light generated is generally directed to the dichroic filter 34 as indicated by the arrow 36. The dichroic filter 34 is part of a prism 38. The dichroic filter 34 may be a thin film dichroic filter. The prism 38 is disposed at the outlet of the reflective cavity formed by the cavity housing 32. The dichroic filter 34 may be formed on one surface of the prism 38, in which case a second prism 39 is provided that abuts the side of the prism 38 that includes the dichroic filter 34. Alternatively, the dichroic filter 34 may be formed on one surface of the prism 39, in which case the first prism 38 abuts the side of the prism 39 that includes the dichroic filter. The light transmitted through the dichroic filter 34 passes through the second prism 39. Alternatively, dichroic filter 34 may be the inner surface of a generally cubic or rectangular prism (and thus comprises prism elements 38 and 39 in FIG. 2).

[0036] The prism 38 may be a solid prism, in which case the second prism 39 may also be a solid prism.

[0037] Dichroic filter 34 is positioned at a first angle relative to the incident light (arrow 36) and acts to filter the incident light 36 by transmitting a portion of the light in the incident light 36 through dichroic filter 34 and reflecting a portion of the light in the incident light 36 from dichroic filter 34 based on the cutoff wavelength of the dichroic filter.

[0038] In the embodiment shown in Fig. 2, the light that becomes the treatment light is light having a wavelength that exceeds the cut-off wavelength, and therefore the dichroic filter 34 is configured to transmit light having a wavelength that exceeds the cut-off wavelength, and light having a wavelength that is equal to or less than the cut-off wavelength is reflected by the dichroic filter 34. The transmitted light (in this embodiment, the treatment light) is indicated by arrow 40, and the reflected light (in this embodiment, the unwanted light) is indicated by arrow 42. The cut-off wavelength can be between 500 nm and 600 nm, for example 530 nm or 565 nm. If the treatment is other than hair removal / reduction, the cut-off wavelength can have a different value. The cut-off wavelength is defined by the average angle of incidence of the light incident on the dichroic filter.

[0039] The transmitted light 40 is directed to the light exit window 10, through which it can exit the processing device 30. The reflected light 42 is directed to a beam dump 44, which absorbs light, particularly light having wavelengths in at least a range corresponding to the wavelengths of light in the reflected light 42. A heat sink 46 is coupled to the beam dump 44, which serves as a dissipation of heat from the beam dump 44.

[0040] In the illustrated embodiment, the dichroic filter 34 is positioned at a 45° angle with respect to the incident light 36, and the beam dump 44 / heat sink 46 is positioned at a 90° angle with respect to the incident light 36. However, in alternative embodiments, the angle of the dichroic filter 34 with respect to the incident light 36 can be other than 45°. For example, the angle can be close to 45° or any angle between 30° and 60°. Similarly, the angle of the beam dump 44 with respect to the incident light 36 can be other than 90°, but preferably the beam dump 44 is positioned with respect to the dichroic filter 34 to capture as much of the reflected light component 42 as possible.

[0041] Because the beam dump 44 and heat sink 46 are located away from the light exit window 10, which is typically placed in contact with the subject's skin, the processing device 30 is not perceived as hot to the subject during use. Furthermore, absorbed heat is efficiently dissipated, resulting in heat sink temperatures that are typically lower than the 200° C. or more temperatures found in conventionally designed absorptive filters.

[0042] The beam dump 44 can be made of any suitable material and have any suitable structure. For example, the beam dump can be a cone-shaped beam trap of a blackened material such as a metal. More simply, the beam dump 44 can be a "black" layer with high absorption and low reflectance. Examples of suitable black materials are black anodized aluminum, nickel-phosphorus alloys, and coatings based on carbon nanotubes.

[0043] The heat sink 46 can be made of any suitable material and have any suitable construction. For example, the heat sink can be a base with fins to increase the contact area with the airflow through the fins. It can be made of a single material such as copper or aluminum alloy. Alternatively, sheet metal fins can be soldered to the base.

[0044] The beam dump and heat sink may be combined into a single element, for example made of anodized aluminum.

[0045] As mentioned above, in the embodiment of FIG. 2, in addition to the dichroic filter 34, the processing device 30 also has an optional absorbing filter 48. The absorbing filter 48 is arranged between the dichroic filter 34 and the light exit window 10 such that the transmitted light component 40 passes through the absorbing filter 48. The absorbing filter 48 can be a separate optical element or it can be embedded in the light guide. The absorbing filter 48 is configured to absorb light of wavelengths corresponding to unwanted light when light having a wavelength equal to or less than the cutoff wavelength of the dichroic filter 34 (in this example) reaches the light exit window 10. Notably, in practice, the cutoff wavelength of the dichroic filter 34 is usually not a sharp cutoff but has a transition over a finite wavelength width. Furthermore, the effect of the dichroic filter 34 is also influenced by the angle at which the light is incident on the dichroic filter 34. Thus, a part of the light having a wavelength equal to or less than the cutoff wavelength of the dichroic filter 34 can be transmitted by the dichroic filter 34 and is absorbed by the absorbing filter 48. With good dichroic filter design, i.e., by incorporating sufficient dielectric layers, the leakage of unwanted light through the dichroic filter 34 can be limited. As a result, the power absorbed by the absorptive filter 48 is a small fraction of the power absorbed by the absorptive filter in a conventional absorptive filter only design. In effect, the reflected light component is removed from the light engine of the processing device 30, thereby avoiding the recycling / reflection problem in conventional devices with dichroic filters.

[0046] Following the absorbing filter 48 in the optical path of the transmitted light component 40 is an optional light guide 50 through which the filtered transmitted light component 40 passes to exit the treatment device 30. The light guide 50 may be part of the light exit window 10, or may be separate from the light exit window 10. In some embodiments, the light guide 50 is not present. In some embodiments, the light guide 50 may be part of a removable attachment that is attached to the treatment device 30 to change the characteristics of the emitted light. For example, one type of attachment may provide a narrow opening to reduce the area of ​​skin exposed to the transmitted light component 40, while another type of attachment may provide a wider opening so that a larger area of ​​skin is exposed to the transmitted light component 40.

[0047] 2, an optional gap 52 is shown between the beam dump 44 and the surface 54 of the prism 38, through which the reflected light component 42 exits the prism 38. This gap 52 can be an air gap or a gap filled with another material having a lower refractive index than the prism 38. This low refractive index gap or boundary 52 is beneficial to promote or cause total internal reflection (TIR) ​​of light from the light source 12 that is incident on the surface 54 before encountering the dichroic filter 34. This gap 52 thus avoids or minimizes the loss of light components of desired wavelengths (i.e., light components that become part of the transmitted light component 40) to the beam dump 44.

[0048] A further gap 56 is shown between the second prism 39 and the absorbing filter 48. This gap 56 is not essential and the absorbing filter 48 may also be in contact with the second prism 39.

[0049] It should be noted that the low refractive index at the entrance side of the first prism 38 (which may be provided by the air in the cavity housing 32) may help confine the reflected light component 42 (which has some angular spread around the mean propagation direction indicated by the arrow) within the prism 38 by total internal reflection before it exits the prism 38 via the surface 54.

[0050] Turning now to Figure 3, as previously discussed, in the set of embodiments depicted in Figure 3, the dichroic filter is configured such that the reflected light component is the component of light that performs the processing operation, and the reflected light component exits the processing device through the light exit window, and the transmitted light component is incident on and received by the beam dump.

[0051] Accordingly, in Figure 3, a portion of a processing apparatus 60 according to a second set of embodiments is shown. The processing apparatus 60 has a light source 12 disposed within a cavity housing 62 of the processing apparatus 60. The light source 12 can be controllable or configured to generate pulses of light (e.g. IPL), or continuous light, or relatively continuous light.

[0052] The cavity housing 62 forms a reflective cavity for the light source 12 such that the light generated is generally directed towards the dichroic filter 64 as indicated by the arrow 66. The dichroic filter 64 is part of a prism 68. The dichroic filter 64 may be a thin film dichroic filter. The prism 68 is disposed at the outlet of the reflective cavity formed by the cavity housing 62. The dichroic filter 64 is formed or provided on one surface of the prism 68, in which case a second prism 69 is provided abutting the surface of the prism 68 that includes the dichroic filter 64. Alternatively, the dichroic filter may be formed on one surface of the prism 69, in which case the first prism 68 abuts the surface of the prism 69 that includes the dichroic filter. The light transmitted through the dichroic filter 64 passes through the second prism 69. Alternatively, the dichroic filter 64 may be provided on the inner surface of a generally cubic or rectangular prism (and thus has prism elements 68 and 69 in FIG. 3). In this configuration, where the transmitted light component 72 is incident on and received by the beam dump 74, the second prism 69 may be a thin plate (cubic prism), in which case the beam dump 74 is in optical contact with it, or the second prism 69 may be omitted, in which case the beam dump is in direct optical contact with the dichroic filter 64.

[0053] The prism 68 may be a solid prism, in which case the second prism 69 may also be a solid prism.

[0054] Dichroic filter 34 is positioned at a first angle relative to the incident light (arrow 66) and acts to filter the incident light 66 by transmitting a portion of the light in the incident light 66 through dichroic filter 64 and reflecting a portion of the light in the incident light 66 from dichroic filter 64 based on the cutoff wavelength of the dichroic filter.

[0055] In the embodiment shown in Figure 3, the light that becomes the treatment light is light having a wavelength above the cut-off wavelength, and therefore the dichroic filter 64 is configured to reflect light having a wavelength above the cut-off wavelength, and light having a wavelength equal to or less than the cut-off wavelength is transmitted through the dichroic filter 64. The reflected light (in this embodiment, the treatment light) is indicated by arrow 70, and the transmitted light (in this embodiment, the unwanted light) is indicated by arrow 72. The cut-off wavelength can be between 500 nm and 600 nm, for example 530 nm or 565 nm. If the type of treatment is other than hair removal / reduction, the cut-off wavelength can have a different value.

[0056] The transmitted light 70 is directed to the light exit window 10 through which it can exit the processing device 60. The transmitted light 72 is directed to a beam dump 74 which absorbs light, and in particular absorbs light having at least a range of wavelengths corresponding to the wavelengths of light of the transmitted light 72. A heat sink 76 is coupled to the beam dump 74 which serves as a dissipation of heat from the beam dump 74.

[0057] In the illustrated embodiment, the dichroic filter 64 is positioned at an angle of 45° with respect to the incident light 66, and the light exit window 10 is positioned at an angle of 90° with respect to the incident light 66. However, in alternative embodiments, the angle of the dichroic filter 64 with respect to the incident light 66 can be other than 45°. For example, the angle can be close to 45° or any angle between 30° and 60°. Similarly, the angle of the light exit window 10 with respect to the incident light 66 can be other than 90°, but preferably the light exit window 10 is positioned with respect to the dichroic filter 64 to receive as much of the reflected light component 70 as possible.

[0058] The beam dump 74 and heat sink 76 are located away from the light exit window 10, which is typically placed in contact with the subject's skin, so that the processing device 60 is not perceived as hot to the subject during use.

[0059] The beam dump 74 can be made of any suitable material and have any suitable structure. For example, the beam dump can be a cone-shaped beam trap of a blackened material such as a metal. More simply, the beam dump 74 can be a "black" layer with high absorption and low reflectance. Examples of suitable black materials are black anodized aluminum, nickel-phosphorus alloys, and coatings based on carbon nanotubes.

[0060] The heat sink 76 can be made of any suitable material and have any suitable construction. For example, the heat sink can be a base with fins to increase the contact area with the airflow through the fins. It can be made of a single material such as copper or aluminum alloy. Alternatively, sheet metal fins can be soldered to the base.

[0061] As mentioned above, in the embodiment of FIG. 3, in addition to the dichroic filter 64, the processing device 60 also has an optional absorbing filter 78. The absorbing filter 78 is arranged between the dichroic filter 64 and the light exit window 10, so that the reflected light component 70 passes through the absorbing filter 78. The absorbing filter 78 can be a separate optical element or it can be embedded in the light guide. The absorbing filter 78 is configured to absorb light of a wavelength corresponding to the transmitted unwanted light when light having a wavelength equal to or less than the cutoff wavelength of the dichroic filter 64 (in this example) reaches the light exit window 10. Notably, in practice, the cutoff wavelength of the dichroic filter 64 is usually not a sharp cutoff but has a transition over a finite wavelength width. Furthermore, the effect of the dichroic filter 64 is influenced by the angle at which the light is incident on the dichroic filter 64. Thus, a part of the light having a wavelength equal to or less than the cutoff wavelength of the dichroic filter 64 can be reflected by the dichroic filter 64 and absorbed by the absorbing filter 78. With good dichroic filter design, i.e., by incorporating sufficient dielectric layers, the leakage of unwanted light through dichroic filter 64 can be limited, so that the power absorbed by absorbing filter 78 is a small fraction of the power absorbed by the absorbing filter in a conventional absorbing-only filter design. Effectively, the transmitted light component is removed from the light engine of processing device 60, thereby avoiding the recycling / reflection problems in conventional devices with dichroic filters.

[0062] Following the absorbing filter 78 in the optical path of the reflected light component 70 is an optional light guide 80 through which the filtered reflected light component 70 passes to exit the treatment device 60. The light guide 80 may be part of the light exit window 10, or may be separate from the light exit window 10. In some embodiments, the light guide 80 is not present. In some embodiments, the light guide 80 may be part of a removable attachment that is attached to the treatment device 60 to change the characteristics of the emitted light. For example, one type of attachment may provide a narrow opening to reduce the area of ​​skin exposed to the reflected light component 70, while another type of attachment may provide a wider opening to allow a larger area of ​​skin to be exposed to the reflected light component 70.

[0063] In FIG. 3, an optional gap 82 is shown between the absorbing filter 78 (or the light guide 80, if present, or simply the light exit window 10 in other embodiments) and the surface 84 of the prism 68 where the reflected light component 72 exits the prism 68. This gap 82 can be an air gap or a gap filled with another material with a lower refractive index than the prism 68. This low index gap or boundary 82 is beneficial to encourage or cause total internal reflection (TIR) ​​of light from the light source 12 that enters the surface 84 before encountering the dichroic filter 64. This gap 82 thus avoids or minimizes light components of unwanted wavelengths (i.e., those that do not become part of the reflected light component 70) from exiting the processing device 60 through the light exit window 10 and entering the target. Note that the hollow waveguide 80 adjacent to the surface 84 effectively forms a low index boundary even if the waveguide is in contact with the prism 68.

[0064] In FIG. 3, another optional gap 86 is shown between the cavity housing 62 into which the light 66 generated by the light source 12 enters and the prism 68. This gap 86 can be an air gap or a gap filled with another material having a lower refractive index than the prism 68. This low refractive index gap or boundary 86 is beneficial to promote or cause total internal reflection (TIR) ​​of a portion of the reflected light components 70 (having some angular spread around the mean propagation direction shown by the arrow) that enters the surface 90 before exiting the prism 68 through the surface 84. This gap 86 thus avoids or minimizes light intended for processing from being reflected back to the light source 12. Note that the hollow cavity housing adjacent to the surface 90 effectively forms a low refractive index boundary even if the cavity housing is in contact with the prism 68.

[0065] The beam dump 74 / heat sink 76 may be in contact with the surface of the second prism 69 where the transmitted light component 72 exits the prism 69, or it may be spaced from the surface of the second prism 69 by a gap 88.

[0066] Figures 4(a) and (b) show some exemplary dichroic filter and prism configurations. These examples can be used in the embodiments shown in Figures 2 and 3. As mentioned above, the dichroic filter 34;64 is part of the prism 38;68. The dichroic filter 34;64 may be formed on one surface of the prism 38;68, in which case a second prism 39;69 is provided that abuts the surface of the first prism 38;68 that comprises the dichroic filter 34;64. Alternatively, the dichroic filter 34 may be an inner surface of a generally cubic or rectangular prism (and thus has prism elements 38 and 39 in Figure 2, or elements 68 and 69 in Figure 3).

[0067] A prism with embedded or integrated dichroic filters can be made in a similar way to a dichroic cube or cuboid. It starts with two complementary prisms, for example prisms 38 and 39 or 68 and 69. These prisms are made of glass or optical polymers. A dielectric multilayer filter is deposited on the face of one prism that contacts the other prism. Usually this multilayer dichroic filter is symmetric. As a result, the function of the dichroic filter is the same for both directions of incidence. The two prisms can be glued together by glue or cement or by optical contact. Figure 4(a) shows a cuboid prism 100 with a dichroic filter 106 embedded between a first solid prism 102 and a second solid prism 104. The prisms 102, 104 are rounded cubes. FIG. 4(b) shows an alternative configuration in the form of a dichroic cube 110 made from two right angle prisms 112, 114 with equilateral isosceles triangular end faces and a dichroic filter 116 between them.

[0068] In some embodiments, one or more surfaces in the arrangements shown in Figures 2 and 3 can be provided with an anti-reflective coating to minimize recycling / reflection of unwanted light and / or maximize transmission of the process light. For example, the surface where the unwanted light component exits the prism or other solid light guide towards a medium with a lower refractive index (typically air). In other aspects, Fresnel reflections at the interface reflect some energy in the unwanted wavelength range back into the optical system, which increases the thermal load of the absorbing filter 48, 78 (if present) or increases the amount of unwanted light entering the target through the light exit window 10. In the arrangement shown in Figure 2, an anti-reflective coating can be applied to the surface 54. In the arrangement shown in Figure 3, an anti-reflective coating can be applied to the surface adjacent to the beam dump 74 where the transmitted light component 72 exits the second prism 69 if the beam dump 74 is not in optical contact with this exit surface. As another example, the surface where the process light exits the prism towards a medium with a lower refractive index can be provided with an anti-reflective coating. In other embodiments, Fresnel reflections at the interface reflect energy in the treatment wavelength range, thus reducing the amount of treatment light that reaches the skin. In the arrangement shown in Figure 2, an anti-reflective coating can be applied to the surface where the transmitted component 40 exits the prism 39. In the arrangement shown in Figure 3, an anti-reflective coating may be applied to surface 84. For the same reasons, it is useful to apply an anti-reflective coating to the surface where light generated by the light source enters the prism from a medium with a low refractive index.

[0069] Simulation results for a multi-layer dichroic filter with a cutoff wavelength of about 600 nm show that most of the incident optical power below the cutoff wavelength of 600 nm is transmitted to the beam dump 74 and heat sink 76. The results show that higher wavelengths (i.e., above 600 nm) are reflected by the dichroic filter 64 towards the light exit window 10 and the subject's skin.

[0070] 5 is a simplified diagram of a portion of a processing device 130 according to a third set of embodiments. In the third set of embodiments, the processing device 130 includes a light source 12, a cavity housing 132, a dichroic filter 134, a prism 136, a second prism 138, a beam dump 140, and a heat sink 142, which may correspond to and / or be similarly configured and / or used as the light source 12, the cavity housing 32, the dichroic filter 34, the prism 38, the second prism 39, the beam dump 44, and the heat sink 46, respectively, in the first set of embodiments described above with reference to FIG.

[0071] In a third set of embodiments, the processing device 130 has a transmissive absorptive filter 144 combined with the dichroic filter 134. For example, the dichroic filter 134 can be deposited on top of the absorptive filter plate 144. The absorptive filter 144 is configured to pass light components in the processing wavelength range and absorb wavelengths of light in the unwanted wavelength range. In this way, the number of interfaces to the light can be reduced and reflected light losses can be minimized, while the reduced absorption of light by the absorptive filter 144 (because most of the unwanted light is reflected by the dichroic filter 134) means that the temperature can be kept low enough so that all elements (the absorptive filter 144 (with the dichroic filter 134) and the prisms 136 and 138) can be bonded or optically contacted.

[0072] As mentioned above, the presented embodiments can reduce the amount of unwanted light that reaches the absorbing filter (if present) or that exits the processing device through the light exit window. A fourth set of embodiments described below with reference to Figure 6 is a variation of the second configuration, where the dichroic filter is configured such that the reflected light component is the component of the light that performs the processing operation, and the reflected light component exits the processing device through the light exit window. This variation provides an alternative to the use of a solid prism 68.

[0073] Briefly, the fourth set of embodiments extends the second set of embodiments shown in Figure 3 by providing a reflective cavity design that helps prevent direct emission of light from the light source towards the light exit window (i.e., any light that is not incident on the dichroic filter), ensuring that the light is efficiently filtered.

[0074] 6 is therefore an illustration of a portion of a processing device 150 according to a fourth set of embodiments. Elements and features of the processing device 150 common to the processing device 60 according to the second set of embodiments of FIG. 3 use the same reference numerals, and the details provided above with respect to these elements and features also apply to the processing device 150. The cavity housing 152 thus forms a reflective cavity for the light source 12 such that the generated light is generally directed towards the dichroic filter 64 as indicated by the arrow 154. This cavity housing 152 is referred to as the diverging cavity 152 because it shapes / reflects the light generated by the light source towards the dichroic filter 64 such that the angular distribution of the light exiting the diverging cavity 152 is concentrated around the optical axis 154. In some embodiments, the diverging cavity 152 is a conical cross section or resembles a conical cross section.

[0075] Despite the narrowing of the angular distribution of the light through the diverging cavity 152, it is still possible for the light to be directed to the light exit window 10, avoiding the dichroic filter 64. Therefore, a converging cavity 156 is provided in front of the light exit window 10. In some embodiments, the light exit window 10 can be at or near the apex of the converging cavity 156. As shown in FIG. 6, the diverging cavity 152 and the converging cavity 156 are at an angle of 90° (or close to 90°) with respect to each other. In some embodiments, the converging cavity 156 is a conical cross section or resembles a conical cross section.

[0076] The converging cavity 156 is shaped and positioned to reflect (possibly via the dichroic filter) light that enters the converging cavity 156 directly from the diverging cavity 152 (i.e., light that did not first interact with the dichroic filter 64) back towards the diverging cavity 152. This reflected light is represented by arrow 158. Thus, when light 154 from the light source 12 enters the converging cavity 156 directly, the light is directed towards the light source 12 via reflection from the walls of the converging cavity 156 before reaching the light exit window 10. As a result, direct emission from the light source 12 to the light exit window 10 is prevented, ensuring that substantially all light is efficiently filtered by the dichroic filter 64, except for a small portion (a few percent or less) of light (based on the exact design of the diverging and converging portions) and / or light scattered from remaining surface roughness of the reflector.

[0077] 6, dichroic filter 64 is a surface of prism 160, which may be rectangular or generally rectangular in cross section. Beam dump 74 and heat sink 76 are positioned adjacent opposite faces of prism 160 such that light transmitted by dichroic filter 64 passes through prism 160 and into beam dump 74.

[0078] The beam dump 74 / heat sink 76 may be in contact with the surface of the prism where the transmitted light component exits the prism, or it may be spaced from the surface of the prism 160 .

[0079] In some embodiments, an absorbing filter 78 can be additionally provided to absorb this residual light and / or any potentially harmful or unwanted portions of the spectrum of light that was not completely filtered by the dichroic filter from reaching the skin. Because the amount of light that needs to be absorbed by the absorbing filter 78 is strongly reduced, there is almost no temperature rise of the absorbing filter 78 during operation of the processing device 150 as in conventional configurations. The absorbing filter 78 can also act as an electrical isolator for the high voltage of the diverging cavity 152, which also acts as a light exit window 10 for efficient light delivery and IPL pain relief.

[0080] Simulations show that by careful design of the diverging cavity 152 and the converging cavity 156, the unwanted portion of the unfiltered exposure dose on the absorbing filter at or near the light exit window 10 can be reduced to only a few percent of the total, allowing the absorbing filter to be kept essentially at room temperature and safe to touch under all processing conditions.

[0081] Thus, a processing device is provided in which unwanted light components are directed to a beam dump where they are absorbed, and heat generated at the beam dump due to the absorption of light is dissipated via an associated heat sink, which reduces heat build-up within the processing device, thereby improving the user experience when operating the processing device.

[0082] Variations to the disclosed embodiments can be understood and implemented by those skilled in the art implementing the principles and techniques described herein, from a study of the figures, the disclosure, and the appended claims. In the claims, the word "comprises" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. The computer program can be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless communication systems. Any reference signs in the claims should not be interpreted as limiting the scope of the invention.

Claims

1. 1. A processing device for performing a light-based processing operation on or to an object, comprising: a light source for generating light for performing said processing operations; a dichroic filter disposed at a first angle with respect to incident light, the incident light being separated into a transmitted light component and a reflected light component based on a cutoff wavelength of the dichroic filter, the transmitted light component being transmitted through the dichroic filter, and the reflected light component being reflected by the dichroic filter; a light exit window disposed relative to the dichroic filter, through which one of the transmitted light component and the reflected light component is emitted from the processing device; and a beam dump configured and arranged relative to the dichroic filter, wherein the other of the transmitted light component and the reflected light component is incident on the beam dump and absorbed by the beam dump; a heat sink coupled to the beam dump for dissipating heat from the beam dump; The processing device, wherein the dichroic filter is provided on a first surface of a solid dichroic prism or an inner surface of a solid dichroic cuboid.

2. The processing device of claim 1 , further comprising an absorption filter disposed relative to the dichroic filter and the light exit window, wherein one of the transmitted light component and the reflected light component emitted from the processing device through the light exit window passes through the absorption filter.

3. The processing device according to claim 2 , wherein the absorption filter absorbs light having a wavelength corresponding to the wavelength of the other of the transmitted light component and the reflected light component.

4. 4. The processing device according to claim 2 or 3, wherein the absorption filter is combined with the dichroic filter.

5. 5. The processing device of claim 1, further comprising a second prism arranged in contact with the first surface of the solid dichroic prism when the dichroic filter is provided on the first surface of the solid dichroic prism, and a light component transmitted by the dichroic filter passes through the second prism.

6. 6. The processing device of claim 5, wherein a low refractive index boundary is provided on a second surface of the dichroic prism through which the reflected light component exits the dichroic prism, the low refractive index boundary having a lower refractive index than the dichroic prism.

7. 5. The processing device of claim 1, wherein when the dichroic filter is provided on an inner surface of a solid dichroic cuboid, a low refractive index boundary is provided on a first surface of the dichroic cuboid, and the reflected light component passes through the first surface and exits the dichroic cuboid, the low refractive index boundary having a lower refractive index than the dichroic cuboid.

8. 8. The processing device of claim 1, wherein the dichroic filter, the light exit window and the beam dump are configured relative to each other such that the transmitted light component is emitted from the processing device through the light exit window and the reflected light component is incident on the beam dump.

9. 9. The processing apparatus of claim 8, wherein the dichroic filter is configured such that the transmitted light component comprises light having wavelengths above the cutoff wavelength and the reflected light component comprises light having wavelengths equal to or less than the cutoff wavelength.

10. 8. The processing device of claim 1, wherein the dichroic filter, the light exit window and the beam dump are configured relative to each other such that the reflected light component is emitted from the processing device through the light exit window and the transmitted light component is incident on the beam dump.

11. The processing device of claim 10 , wherein the dichroic filter is configured such that the transmitted light component comprises light having wavelengths less than or equal to the cutoff wavelength, and the reflected light component comprises light having wavelengths greater than the cutoff wavelength.

12. 12. The processing device of claim 10 or 11, wherein the processing device has a diverging cavity and a converging cavity, the light source is disposed towards a first end of the diverging cavity, the light exit window is disposed at an end of the converging cavity, and the dichroic filter is disposed between the diverging cavity and the converging cavity.

13. 13. The processing device of claim 12, wherein the convergent cavity and the divergent cavity are configured such that light entering the convergent cavity without reflecting from the dichroic filter is reflected by the convergent cavity away from the light exit window towards the divergent cavity.

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