System and method for tissue treatment

Abstract

To provide an improved method, system, and apparatus for EMR-based (e.g., laser-based) tissue treatment.SOLUTION: A cooling element 150 includes a frame containing one or more data. The cooling element also includes a first window 112 including a first proximal surface and a first distal surface. The first window is sealed within the frame. The cooling element further includes a second window 118 sealed within the frame. The second window includes a second proximal surface and a second distal surface. The second window is configured to contact a target tissue or a tissue adjacent to the target tissue via the second distal surface. Additionally, the cooling element includes a cooling agent chamber arranged between the first distal surface of the first window and the second proximal surface of the second window and configured to accept a cooling agent 116. The first window, the second window, and the cooling agent chamber are configured to receive electromagnetic radiation (EMR) and transmit a part of the received EMR to the target tissue.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] A variety of conditions may be treated by applying light or light energy of specific wavelengths. Many challenges exist in delivering energy to the appropriate target structure (e.g., tissue such as skin) without damaging tissue structures adjacent to the target structure. These challenges include the ability to effectively and efficiently scan the target structure using light or light energy, as well as the ability to deliver energy at the appropriate wavelength with sufficient fluence. [Background technology]

[0002] Melasma is an example of a skin disease of unknown etiology that often causes patchy hyperpigmentation on the facial area. The condition is more prevalent in women than in men. The specific cause of melasma is not well understood, but melasma pigmentation can be further exacerbated by several conditions, such as pregnancy, sun exposure, certain medications such as oral contraceptives, hormone levels, and genetic factors. Typical symptoms of melasma include dark, irregularly shaped spots or macules that are commonly found on the upper cheeks, nose, upper lip, and forehead. These spots gradually grow larger over time. Melasma does not cause any other symptoms or have any other harmful effects other than the outward discoloration.

[0003] Unlike many pigmented structures that are normally present in the epidermal region of the skin (e.g., at or near the tissue surface), dermal (or deep) melasma is often characterized by the widespread presence of melanin and melanophages (e.g., containing hyperpigmented cells) in parts or regions of the lower dermis. Therefore, treating dermal melasma (e.g., lightening the appearance of pigmented dark areas) can be particularly difficult because it is very difficult to access and affect such pigmented cells and structures located deeper within the skin. Therefore, conventional skin rejuvenation treatments such as face peels (laser or chemical), dermabrasion, topical agents, etc., which mainly affect the epidermis, may not be effective in treating dermal melasma. Summary of the Invention [Problem to be solved by the invention]

[0004] It has been observed that application of light or light energy of certain wavelengths can be strongly absorbed by pigmented cells, thereby damaging them. However, effective treatment of dermal melasma using light energy incurs several obstacles. For example, pigmented cells in the dermis must be targeted with sufficient light energy of the appropriate wavelength to destroy or damage the cells, which may release or destroy some of the pigmentation, reducing pigmentation. However, such energy may be absorbed by pigments (e.g., chromophores) in overlying skin tissues, such as the epidermis and upper dermis. Such near-surface absorption may result in excessive damage to the outer portions of the skin, resulting in insufficient energy transfer to the deeper dermis to affect the pigmented cells therein. Also, thermal damage to melanocytes located in the basal layer of the epidermis may cause increased melanin production, and thermal damage leading to the destruction of melanocytes may cause reduced pigmentation. It is therefore desirable to cool (i.e., transfer heat away from) non-targeted tissue, particularly the pigmented epidermal tissue located directly above the dermal spot. Ideally, cooling occurs simultaneously with the therapeutic radiation and on the same tissue surface as the radiation.

[0005] A fractional approach has been developed that applies light energy to small, discrete treatment locations on the skin separated by healthy tissue to promote healing. It can be difficult to precisely target a treatment location (e.g., in the epidermis layer) with the desired specificity while avoiding damage to healthy tissue surrounding the treatment location (e.g., in the epidermis layer). This is the case, for example, with laser beams. The current state of the art requires an optical system with a high numerical aperture (NA) to focus the EMR beam at the treatment location. The optical system also needs to be able to scan the focused beam over a large affected area (e.g., several square centimeters). It is therefore desirable to develop an optical system that can have a high numerical aperture and can scan a large affected area. It is also desirable for the interface to establish a firm contact with the treatment area to stabilize the treatment area and allow the depth of the focused laser beam to be maintained within the treatment area. Furthermore, it may be advantageous for the interface to cool the treatment area simultaneously with the therapeutic radiation to prevent undesired thermal damage. For at least the above reasons, improved methods, systems, and apparatus for EMR-based (e.g., laser-based) tissue treatment are provided. [Means for solving the problem]

[0006] In one embodiment, the system includes an optical element configured to receive electromagnetic radiation (EMR) and focus the EMR along an optical axis to a focal region of a target tissue. The system also includes a cooling element down-beam from the optical element and configured to receive the focused EMR. The cooling element includes a first window including a first proximal surface and a first distal surface. The first window is sealed to the frame. The cooling element further includes a second window sealed to the frame. The second window includes a second proximal surface and a second distal surface. The second window is configured to contact the target tissue or tissue adjacent to the target tissue via the second distal surface. The cooling element also includes a coolant chamber disposed between the first distal surface of the first window and the second proximal surface of the second window and configured to receive a coolant. The first window, the second window, and the coolant chamber are configured to receive the electromagnetic radiation (EMR) and transmit a portion of the received EMR to the target tissue.

[0007] In one embodiment, the controller is configured to vary a first distance between the focal region and the second distal surface of the second window along the optical axis by varying a second distance between the optical element and the second distal surface of the second window along the optical axis. In other embodiments, the first distance varies between a first predetermined value and a second predetermined value as the focal region traverses along the treatment path of the target tissue. In yet other embodiments, the difference between the first predetermined value and the second predetermined value is less than 0.25 mm. In yet other embodiments, the first predetermined value is 0.001 mm and the second predetermined value is 10 mm.

[0008] In one embodiment, the controller is configured to vary a first distance between the focal region and the second distal surface of the second window along the optical axis by varying a divergence associated with the EMR. In another embodiment, the system further includes a scanning device. The scanning device is configured to receive a control signal from the controller and move the optical element along a first scanning path based on the control signal. In yet another embodiment, the first scanning path is substantially parallel to the second distal surface of the second window.

[0009] In one embodiment, the controller is configured to vary the intensity of the EMR radiation. In another embodiment, the controller is configured to vary the flow rate of the coolant in the coolant chamber. In yet another embodiment, the optical element has a numerical aperture (NA) in the range of about 0.1 to about 1.0.

[0010] In one embodiment, the EMR has an average power in a range of about 1 W to about 100 W. In another embodiment, the EMR includes a pulsed laser beam having a wavelength in a range of about 400 nm to about 4000 nm. In yet another embodiment, the EMR is configured to generate a thermionic plasma at a focal region. In another embodiment, the cooling element further includes a gas source configured to direct a gas toward the first window, the gas configured to prevent condensation on the first window.

[0011] In one embodiment, a method includes generating focused electromagnetic radiation (EMR) and transmitting the focused EMR through a cooling element having a first proximal surface and a first distal surface. The cooling element further includes a second window sealed to the frame. The second window includes a second proximal surface and a second distal surface. The second window is configured to contact the target tissue or tissue adjacent to the target tissue via the second distal surface. The cooling element also includes a coolant chamber disposed between the first distal surface of the first window and the second proximal surface of the second window and configured to receive a coolant. The method further includes directing the focused EMR to a focal region of the target tissue.

[0012] In one embodiment, generating the focused EMR includes positioning an optical lens along an optical axis of the EMR. In another embodiment, the method further includes varying the depth of the focal region within the target tissue by varying the position of the optical lens along the optical axis. In another embodiment, the depth of the focal region ranges from about 0.001 mm to about 10 mm.

[0013] In one embodiment, the method further includes scanning the focused EMR along a treatment path of the target tissue, hi other embodiments, the focused EMR beam is scanned along the treatment path by moving the optical element substantially parallel to the second distal end of the second window.

[0014] In one embodiment, the cooling element includes a frame including one or more datums. The cooling element also includes a first window including a first proximal face and a first distal face. The first window is sealed to the frame. The cooling element further includes a second window sealed to the frame. The second window includes a second proximal face and a second distal face. The second window is configured to contact the target tissue or tissue adjacent to the target tissue via the second distal face. The cooling element also includes a coolant chamber disposed between the first distal face of the first window and the second proximal face of the second window and configured to receive a coolant. The first window, the second window, and the coolant chamber are configured to receive electromagnetic radiation (EMR) and transmit a portion of the received EMR to the target tissue.

[0015] In one embodiment, the one or more datums are disposed at the datum plane. The second window is disposed at a first angle relative to the datum plane. The first angle is less than 1.0 mrad. In another embodiment, the coolant chamber includes a port configured to direct coolant from a coolant flow source into the coolant chamber. In yet another embodiment, the first window is sealed to the frame via a first seal and the second window is sealed to the frame via a second seal. The first seal includes one or more of an adhesive, a weld, a solder, a braze, a polymer, and an elastomer.

[0016] In one embodiment, a first thermal effusivity associated with the first window is lower than a second thermal effusivity associated with the second window. In another embodiment, a first thickness associated with the first window is greater than a second thickness associated with the second window. In yet another embodiment, the cooling element further includes a gas source configured to direct a gas toward the first window. The gas is configured to prevent condensation on the first window.

[0017] In one embodiment, the second distal surface of the second window has one or more of a planar shape, a convex shape, and a concave shape. In another embodiment, the cooling element further comprises a fastener. The fastener is configured to secure the second distal surface of the second window to the frame. In yet another embodiment, the fastener comprises at least one of a screw, a clamp, a snap, a retaining ring, and a tab.

[0018] In one embodiment, the second window comprises at least one of sapphire, quartz, or diamond. In another embodiment, the first window is disposed at a second angle relative to the second window, the second angle being less than 10 mrad. In yet another embodiment, the second window downbeams from the first window. In another embodiment, a portion of the received EMR is transmitted to a focal region of the target tissue.

[0019] In one embodiment, the method includes directing EMR to a cooling element. The cooling element includes a frame including one or more datums. The cooling element also includes a first window including a first proximal face and a first distal face. The first window is sealed to the frame. The cooling element further includes a second window sealed to the frame. The second window includes a second proximal face and a second distal face. The second window is configured to contact the target tissue or tissue adjacent to the target tissue via the second distal face. The cooling element also includes a coolant chamber disposed between the first distal face of the first window and the second proximal face of the second window and configured to receive a coolant. The first window, the second window, and the coolant chamber are configured to receive electromagnetic radiation (EMR) and transmit a portion of the received EMR to the target tissue.

[0020] In one embodiment, transmitting a portion of the EMR to the target tissue includes focusing the EMR to a focal region of the target tissue. In another embodiment, the one or more datums are disposed at a datum plane. The second window is disposed at a first angle relative to the datum plane, the first angle being less than 1.0 mrad. In yet another embodiment, the coolant chamber includes a port configured to direct coolant from a coolant flow source to the coolant chamber. In another embodiment, the first window is sealed to the frame via a first seal and the second window is sealed to the frame via a second seal.

[0021] Embodiments of the present disclosure will become more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0022] [Figure 1]1 illustrates a schematic diagram of a system for radiating and cooling tissue, according to some embodiments. [Figure 2A] 1 illustrates a schematic diagram of a system for varying a working distance of a focal point of an electromagnetic radiation beam, according to some embodiments; [Figure 2B] 2A-2C illustrate schematic diagrams of different systems for varying the working distance of a focal spot of an electromagnetic radiation beam, according to some embodiments; [Diagram 3] 1 illustrates a schematic diagram of a system for scanning an electromagnetic radiation beam across at least one axis, according to some embodiments; [Figure 4A] 1A-1C are schematic diagrams illustrating multiple views of a system for radiating and simultaneously cooling tissue, according to some embodiments. [Figure 4B] 1A-1C are schematic diagrams illustrating multiple views of a system for radiating and simultaneously cooling tissue, according to some embodiments. [Figure 4C] 1A-1C are schematic diagrams illustrating multiple views of a system for radiating and simultaneously cooling tissue, according to some embodiments. [Figure 4D] 1A-1C are schematic diagrams illustrating multiple views of a system for radiating and simultaneously cooling tissue, according to some embodiments. [Diagram 5] 1 is a flowchart illustrating a method for irradiating and cooling tissue, in accordance with some embodiments. [Figure 6] FIG. 1 is a schematic diagram of a laser beam focused on a pigmented area of ​​the dermis layer of the skin. [Figure 7A] 1 is a graph of an exemplary absorbance spectrum of melanin. [Figure 7B] 1 is a graph of an exemplary absorbance spectrum of hemoglobin. [Figure 8] 1 shows a plot of the absorption coefficient of melanin and venous blood, and the scattering coefficient of light in skin versus wavelength. [Figure 9A] 1 is a graph illustrating the cooling performance of several exemplary cooling elements. [Figure 9B] 1 shows a schematic diagram of an exemplary cooling element. [Figure 9C] 1 shows a schematic diagram of an exemplary cooling element. [Figure 9D] 1 shows a schematic diagram of an exemplary cooling element.

[0023] It should be noted that the drawings are not necessarily to scale. The drawings are intended to depict only typical aspects of the subject matter disclosed herein and therefore should not be considered as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the systems, apparatus, and methods specifically described herein and shown in the accompanying drawings are non-limiting exemplary embodiments, the scope of which is defined only by the claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Certain exemplary embodiments are described herein to provide a general understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

[0025] The embodiments of the present invention are discussed in detail below with respect to the treatment of skin pigmentary conditions such as melasma to improve the appearance of such pigmentary conditions. However, the disclosed embodiments may be used without limitation for the treatment of other pigmentary and non-pigmentary conditions, as well as other tissue and non-tissue targets. Examples of pigmentary conditions may include, but are not limited to, post-inflammatory hyperpigmentation, dark skin around the eyes, black eyes, cafe au lait patches, Becker's nevus, Nevus of Ota, congenital melanocyte nevi, freckles / lentigo, hemosiderin-rich structures, pigment gallstones, lutein, zeaxanthin, rhodopsin, carotenoids, biliverdin, bilirubin and hemoglobin-rich structures, and tissues including tattoos. Examples of non-pigmented conditions can include, but are not limited to, hair follicles, hair shafts, vascular lesions, infectious conditions, sebaceous glands, acne, etc. Examples of non-dermal tissues include, but are not limited to, soft tissues such as cartilage, mucous membranes, and serous membranes, and hypomanic tissues such as bone and tooth enamel.

[0026] Furthermore, in this disclosure, like-named components of an embodiment generally have similar characteristics, and within a particular embodiment, each feature of each like-named component is not necessarily fully described. Also, to the extent that linear or circular dimensions are used in describing the disclosed systems, devices, and methods, such dimensions are not intended to limit the typology of configurations that can be used in conjunction with such systems, devices, and methods. Those skilled in the art will recognize that equivalent dimensions to such linear and circular dimensions can be readily determined for any geometric configuration. The size and shape of the systems and devices, and their components, as well as the size and shape of the components with which the systems and devices are used, and the methods and procedures with which the systems and devices are used, may depend at least on the anatomical structure of the subject with which the systems and devices are used.

[0027] In general, several high numerical aperture (NA) optical therapy systems have been described that can focus electromagnetic radiation (EMR) (e.g., a laser beam) to a treatment area of ​​tissue. The focused laser beam can deliver light energy to the treatment area without damaging the surrounding tissue. The delivered light energy can destroy pigmentation chromophores and / or targets, for example, in the treatment area of ​​the dermal layer of the skin, without affecting surrounding areas of the skin or tissue or other pigmented target areas that are surrounded by unaffected non-target areas (e.g., the epithelial layer, other parts of the skin layer, etc.). In other embodiments, the delivered light energy can induce tattoo removal or modification, or hemoglobin-related treatment. During a typical treatment, large amounts of radiation (e.g., average powers of more than 1 W, 5 W, 10 W, 20 W, or 30 W depending on the wavelength) can be delivered to the tissue. These radiation levels can ultimately cause bulk heating of the tissue, resulting in thermal damage. Bulk Heating of the Tissue To prevent this, cooling of the tissue must be performed. For cooling to be most effective, it is performed simultaneously and in the same location as the irradiation. Previous cooling methods have performed cooling in the same location, but not simultaneously (e.g., cryogenic cooling). Still other methods have been performed that perform cooling simultaneously, but not in the same area as the irradiation.

[0028] Exemplary methods and devices for treating skin conditions with light or light energy are disclosed in U.S. Patent Application Publication No. 2016 / 0199132, entitled "METHOD AND APPARATUS FOR TREATING DERMATOID MELOSA," and U.S. Provisional Application No. 62 / 438,818, entitled "METHOD AND APPARATUS FOR SELECTIVE TREATMENT OF DERMATOID MELOSA," each of which is incorporated by reference in its entirety herein.

[0029] FIG. 1 illustrates an exemplary embodiment of a treatment system 100 capable of irradiating and cooling tissue 101. An electromagnetic radiation (EMR) source 102, such as a laser, generates an EMR beam 104. According to some embodiments, the EMR beam 104 has a wavelength in the range between 100 nanometers (nm) and 15000 nm (e.g., between 400 nm and 4000 nm). An exemplary EMR source 102 can be a Q-smart450 from Quantel, Les Ulis, France. The Q-Smart450 can generate an EMR beam 104 (e.g., a pulsed beam) with a wavelength of 1064 nm, a pulse duration between 6 nS and 20 nS (nanoseconds), a repetition rate of up to 40 Hz, and a pulse energy of up to 450 mJ. Another exemplary EMR source 102 is a Coherent Diamond FLQ fiber laser from Coherent, Santa Clara, California. The EMR beam 104 generated by the Diamond FLQ fiber laser can have an average power of up to 10W, 20W, 50W, or 100W, a pulse duration of about 100nS, a pulse energy of up to 1mJ, and a pulse repetition rate between 20KHz and 100KHz. The EMR beam 104 can be focused by an optical element 106 such that the EMR beam 104 converges to a focal point 108 (or "focal region") as the EMR beam 104 propagates along an optical axis 110. According to some embodiments, the EMR beam 104 converges to a focal point 108 having a numerical aperture between 0.1 and 1.0 (e.g., 0.5).

[0030] The treatment system 100 can include a cooling element 150 including a first window 112, a chamber 114 configured to receive / contain a flow of a coolant 116 (e.g., a fluid coolant), and a second window 118. The cooling element can be positioned down-beam from the optical element 106. The term "down-beam" means that the EMR beam 104 first strikes the optical element 106 and then strikes the cooling element 150. In other words, the optical element 106 is positioned up-beam from the cooling element 150.

[0031] The EMR beam 104 can be transmitted through the cooling element 150, which includes the first window 112, the chamber 114 configured to receive / contain a flow of coolant 116, and the second window 118. For example, the first window 112, the coolant 116, and the second window 118 can be substantially transparent to the EMR beam 104. According to some embodiments, the EMR beam can converge (e.g., focus) when transmitting through the first window 112, the chamber 114, the flow of coolant 116, and the second window. The EMR beam 104 can arrive at the focal point 108 after propagating through a distal surface 120 of the second window 118. Between the focal point 108 and the distal surface 120 of the second window 118, there is a working distance 122. According to some embodiments, the working distance 122 can have a value in a range of 0.001 mm to 100 mm (e.g., 0.5 mm, 1.0 mm, and 10 mm).

[0032] According to some embodiments, a flow source 124 of coolant may be provided to induce the flow of coolant 116. The coolant may be located between the first window 112 and the second window 118 (e.g., at a distal surface of the first window 112 and a proximal surface of the second window 118). An exemplary coolant flow source is a compact chiller (part number UC160-190) from Steady State Cooling Systems, Inc., Wappingers Falls, NY. The UC160-190 can generate a coolant flow 124 having a flow rate of 500 ml / min ± 50 ml / min at 9 psig, a maximum pressure of 30 psig, and a coolant temperature between 2°C and 45°C. The coolant may generally be transparent (e.g., greater than 50% transmission) at the wavelength of the EMR beam 104. For example, a mixture of propylene glycol and water is generally transparent in a wavelength range that includes visible light and 1064 nm.

[0033] According to some embodiments, the treatment system 100 further includes a controller 126. The controller may be configured to control the EMR source 102 and the coolant flow source 124, the transmission direction of the EMR beam 104, the position / motion of the optical element 106 (e.g., the path of the optical element 106 relative to the cooling element 150), and the like. According to some embodiments, the temperature of the coolant 116 is controlled to within a few degrees Celsius of a set point. Exemplary coolant temperature set points include -10°C, 0°C, temperatures below 5°C, and temperatures above 10°C. According to some embodiments, the controller 126 controls one or more parameters of the coolant flow source 124, including the coolant set point temperature and the coolant flow rate. According to some embodiments, the controller 126 controls one or more parameters of the EMR source 102, including pulse duration, repetition rate, EMR interlock or gate signal, pulse energy, average power, and the like.

[0034] According to some embodiments, the treatment system 100 is configured to generate plasma in the tissue 101 at or near the focal point 108. In some embodiments, the plasma may be generated via optical means such as photoionization. Generating plasma via photoionization may require large energy densities (e.g., for EMR pulses with pulse durations in the nanosecond range). For example, the irradiance threshold for photoionization of water may be as high as 1013 W / cm2 (e.g., between 105 W / cm2 and 1013 W / cm2). In other embodiments, the plasma may be generated by thermionic emission of electrons. Thermionic generation of plasma may occur in the presence of a chromophore (e.g., a material configured to absorb the EMR beam 104) located at or near the focal point 108 of the EMR beam 104. The high energy density at the focal point may result in ionization of the chromophore and selective thermal damage to the chromophore and possibly materials close to the chromophore. For example, the irradiance threshold for thermionic ionization in an absorbing medium for EMR pulses having pulse durations in the nanosecond range can be as low as 109 W / cm2. Although the selective nature of the focused EMR beam 104 and focal spot 108 can prevent immediate heating of non-target tissue, bulk heating can still occur over many EMR pulses on or near the location of one or more focal spots 108.

[0035] According to some embodiments, the cooling element 150 can cool the tissue 101 when irradiated by the EMR beam 104. In some embodiments, a thermal path can extend from the focal point 108 (e.g., parallel / collinear with the optical axis 110) through the tissue 101, the outer surface of the tissue 101, the distal surface 120 of the second window 118, through the second window 118, and finally to the flow of the coolant 116. This thermal path can be the shortest path (e.g., the shortest path through the tissue 101) from the focal point 108 to the distal surface 120 of the second window 118 from the tissue 101. Thus, the bulk heat of the tissue 101 can be efficiently transferred (e.g., from the location of the focal point 108) to the coolant 116. Because the coolant and the window are both transparent at the wavelength of the EMR beam, cooling may be performed simultaneously with irradiation. Some treatments may require careful control and sometimes modification of the location of the focal point 108 within the tissue. In these cases, it may be desirable for the position of the distal surface 120 of the second window 118 relative to the focal point 108 to be known and / or controlled. For example, a sensor (e.g., an accelerometer, a position detector, etc.) may detect the position of the second window 118 (or the cooling element 150), and this information can be communicated to the controller 126. This allows the position and / or movement of the second window 118 (or cooling element 150) to be tracked.

[0036] Dermal melasma may be treated by selective thermionic plasma in pigment containing dermis. To perform this treatment, it may be desirable to place the focal point 108 of the EMR beam 104 at or near the depth of the pigment in the dermis (e.g., 100 μm to 1 mm below the surface of the tissue 101) (e.g., twice the Rayleigh range). Referring to FIG. 2A, FIG. 2B, a change in depth 200 of the focal point 108 position is shown. FIG. 2A shows a schematic of a change in depth 200 of the focal point 108 according to some embodiments. Translating 210 the optical element 106 relative to the second window 118 along the optical axis 110 (e.g., z-axis) produces a corresponding change 200 in the depth of the focal point 108. According to some embodiments, the optical translation 210 may be generated by a stage and controlled by a controller. An exemplary stage is the M3-FS Focus Module from New Scale Technologies, Victor, NY. In some variations, the controller 126 controls one or more parameters of the stage, including acceleration, velocity, and position.

[0037] According to some embodiments, the depth of the focal spot 108 can be varied by a corresponding change (e.g., change 200) in the divergence 220 of the diverging EMR beam 222. With reference to FIG. 2B, the depth can be varied 200 from a first focal spot position 224 to a second focal spot position 226. The first focal spot position 224 is generated by a wavefront change introduced by the optical element 106 on a first EMR beam 228 having negligible divergence. The second focal spot position 226 is generated by the same optical element 106, but at a different location than the first focal spot position 224 by the added divergence 220. According to some embodiments, the change in divergence 220 is provided from adaptive optics, such as a variable focus lens. An exemplary variable focus lens is Optotune part number EL-10-42-OF from Optotune Switzerland AG. Due to the extreme lateral (e.g., x-axis and y-axis) selectivity (e.g., narrowness) of the focal spot 108, it may be desirable to scan the focal spot 108 over multiple locations within the tissue 101. In some embodiments, the controller 126 can control one or more parameters of the adaptive optics (eg, to change the divergence of the EMR beam).

[0038] Referring to FIG. 3, an embodiment of a system including a beam scanning device 300 is shown in schematic form. Scanning 301 of the optical / EMR beam can result in a translation (or rotation) of the focal position across a scan width 302. The scan width 302 is the distance over which the focal position changes laterally (i.e., in the x-axis and / or y-axis). In some embodiments, the beam scanning device 300 can scan (e.g., move) 301 the EMR focal point, the optics, and the optical axis (or the EMR beam). FIG. 3 shows the scan 301 from a first EMR beam position 314, a first optical position 316, and a first focal position 318 (along the optical axis 320) to a second EMR beam position 304, a second optical position 306, and a second focal position 308 (along the optical axis 310). According to some embodiments, the EMR beam and the optical axis remain incident on the first window 112, the chamber 114, and the second window 118 across the entire scan width. In some embodiments, the depth of the focal spot in the tissue may be controlled. For example, it may be desirable for the direction or plane of the scan 301 to be parallel to the distal surface 120 of the second window 118, within known specifications. This is because, as described above, a change in the distance along the optical axis between the optical device and the distal surface 120 of the second window may result in a change in the working distance 122 and the depth of the focal spot in the tissue. According to some embodiments, the second window 118 is held parallel to the scanning motion within a specified angle (e.g., 10 mrad, 1 mrad, 0.5 mrad, or 0.1 mrad). Alternatively, in some embodiments, the change in the working distance 122 over the scan width 302 may be limited to an acceptable range (e.g., a change in the working distance 122 of 0.25 mm over a scan width of 10 mm). The beam scanning device 300 may be controlled by a controller (e.g., controller 126). In some embodiments, the controller can control one or more parameters of the beam scanning device, including jump speed, acceleration, position, dwell time, etc.

[0039] The exemplary cooling element 400 is shown generally in multiple perspectives in Figures 4A-4D. Figure 4A shows a top isometric view of the cooling element 400 (e.g., a portion of the cooling element 400 facing the EMR source / facing away from the target tissue). Figure 4B shows a bottom isometric view of the cooling element 400 (e.g., a portion of the cooling element 400 facing the target tissue / facing away from the EMR source). Figure 4C shows a bottom view of the cooling element 400. Figure 4D shows a cross-sectional view of the cooling element 400 along the cross-sectional line shown in Figure 4C. The exemplary cooling element 400 includes a frame 402. As shown in Figures 4A and 4C, the frame 402 has three datums 404. The datums 404 correspond to mounts on an energy-based device capable of generating irradiation, allowing the cooling element 400 to be removably attached to and replaced in the energy-based device. According to some embodiments, the datum 404 can approximate one or more geometric forms, such as a plane, a line, and a point. According to some variations, the datum 404 comprises a portion of a kinematic mount (e.g., a Maxwellian mount). The three datums 404 of the exemplary cooling element 400 can be disposed in a plane. The exemplary cooling element 400 further comprises a first window 406 sealed to the frame 402 by a first seal 408 and a second window 410 sealed to the frame 402 by a second seal 412. According to some embodiments, the first seal 408 and the second seal 412 comprise an adhesive. Examples of adhesives can include photocurable adhesives, silicones, and epoxies. According to other embodiments, the first seal 408 and / or the second seal 412 can comprise a weld, braze, or solder, and the corresponding edges of the first window 406 and / or the second window 410 can be metalized, sputtered, or coated with a material (e.g., a metal) that enables such a type of sealing. Additionally, the second window 410 is secured to the frame 402 with one or more fasteners 414. As shown in Figures 4C and 4D, the fasteners 414 of the exemplary cooling element 400 include a clamp plate that is held in place by three machine screws. Additional examples of fasteners may include screws, clamps, snaps, retaining rings, tabs, or any combination thereof.By attaching the second window 410 to the frame, the distal surface 416 of the second window 410 can be positioned in firm contact with tissue without applying additional stress to the second seal 412 that could result in curvature or movement of the distal surface of the second window 410.

[0040] As described above, changes in the distance between the distal surface 416 and the optical element 106 that focuses the EMR beam 104 affect the working distance 122 of the beam and the position of the resulting focal point 108 within the tissue 101. According to some embodiments, the distal surface 416 of the second window 410 may be positioned in a predetermined geometry (e.g., orientation, position, etc.) relative to the datum 404. For example, in some variations, the second window 410 is positioned parallel to a plane approximated by one or more datums 404 within a desired tolerance (e.g., 0.5 mrad). Furthermore, the second window 410 may be positioned at a precise distance along the optical axis (e.g., z-axis) within a desired tolerance (e.g., 0.05 mm). Furthermore, according to some embodiments, the first window 406 and the second window 410 may both be positioned parallel and the predetermined distance between them may be within a desired tolerance (e.g., 0.5 mrad and 0.05 mm). In some embodiments, the first window 406 and the second window 410 can be disposed at an angle relative to one another (e.g., an angle of less than 10 mrad). For various reasons, the distal surface 416 of the second window in some embodiments includes a non-planar shape (e.g., a convex or concave shape). For example, a convex distal surface 416 may be advantageous for compressing tissue when placed in contact with the tissue.

[0041] FIG. 4D shows a chamber 418 within the cooling element 400. The chamber 418 is 4A and 4B show both a coolant supply fitting 422a and a coolant return fitting 422b for supplying coolant to and returning coolant from the chamber 418. FIG. 4A shows both a coolant supply fitting 422a and a coolant return fitting 422b for supplying coolant to and returning coolant from the chamber 418. FIG. 4B ...

[0042] According to some embodiments, the second window comprises a material having a high thermal effusivity (e.g., quartz, sapphire, diamond, etc.). A higher thermal effusivity can allow more heat to be transferred from the tissue surface to the coolant flow. Similarly, according to some embodiments, the first window 406 comprises a material having a lower thermal effusivity (e.g., glass or polymer). An embodiment having a first window 406 with a lower thermal effusivity material can transfer less heat through the first window to the coolant flow. As a result, condensation may occur more slowly than if the first window 406 comprises a high thermal effusivity material. Furthermore, in some embodiments, the first window has a thickness (e.g., 1 mm) that is greater than the thickness of the second window (e.g., 0.5 mm), allowing thermal energy transfer to occur more freely through the second window. According to some examples, condensation can be further prevented by blowing a non-condensing gas, such as clean dry air, nitrogen, carbon dioxide, or argon, over the first window.

[0043] Referring to FIG. 5, a flow chart illustrating a method 500 for irradiating and cooling tissue according to some embodiments is shown. At 502, an electromagnetic radiation (EMR) beam is generated using an EMR source. At 504, a wavefront change is introduced into the EMR beam to cause the EMR beam to converge as it propagates along the optical axis. At 506, the converging EMR beam is transmitted through a first window, a coolant adjacent the first window, and a second window 510 adjacent the coolant. Finally, the converging EMR beam is directed to be incident on a surface area of ​​tissue 512. Simultaneously, heat is transferred 514 from the surface region of the tissue through the second window to the coolant.

[0044] According to some embodiments of the method 500, the converging EMR beam eventually reaches a focal point in the tissue at a depth below the surface area of ​​the tissue. In other variations, the focal depth varies with time. As described above, varying the focal depth in the tissue allows treatments that require energy to be delivered over a range of depths, for example, in dermal melasma treatment. In some variations, the depth varies from 0.001 mm to 10 mm. In some variations, the focused EMR beam has sufficient energy density to cause thermal electronization in pigmented tissue (e.g., energy density greater than about 10 J / cm2 at a pulse duration of 100 nanoseconds and a wavelength of 1064 nm).

[0045] According to some embodiments, the method 500 further includes a step 512 of scanning the converging EMR beam across a scan width in one or more axes and directing the EMR beam to a second surface region of the tissue. Typically, the EMR beam is a pulsed energy source, and each pulse is directed to a new surface region as the EMR beam is scanned. In some variations, the beam scanning is performed in one or more axes that are generally parallel to the distal surface of the second window (along an xy plane parallel to the second window / first window) such that the depth of focus does not vary by more than a desired tolerance (e.g., 0.25 mm or 0.05 mm) across the scan width.

[0046] According to some embodiments, in 502, an EMR beam is generated with an average power of at least as much as 1 W, 5 W, 10 W, or 30 W. In this case, the EMR beam is generated at a wavelength in the range between 400 nm and 4000 nm. According to some embodiments, a wavefront modification is introduced into the EMR beam 504 to result in a convergence of the EMR beam with a ratio related to a numerical aperture (NA) of at least 0.3.

[0047] The following table is provided to summarize example parameters and parameter ranges according to some embodiments. [Table 1]

[0048] [Characteristics of therapeutic radiation] 6 is an exemplary schematic diagram of a laser beam focused on a pigmented region of the dermis layer in skin tissue. The skin tissue includes a skin surface 600 and an upper epidermal layer 610, or epidermis, which may be approximately 30 to 120 μm thick in the facial region, for example. The dermis is the most common dermis in other parts of the body. In some areas, the epidermis may be slightly thicker. For example, epidermis thickness may generally range from about 30 μm (e.g., eyelids) to about 1500 μm (e.g., palms or soles). Such epidermis may be thinner or thicker than the above examples due to certain skin conditions, such as psoriasis. The lower dermal layer 620 or dermis extends from below the epidermis 610 to the deeper subcutaneous fat layer (not shown). Skin exhibiting deep or dermal melasma may include a population of pigmented cells or areas 630 that contain excessive amounts of melanin. Electromagnetic radiation (EMR) 650 (e.g., a laser beam) may be focused on one or more focal areas 660 that may be located within the dermis 620 or epidermis 610. The EMR 650 may be provided at one or more appropriate wavelengths that are absorbed by melanin. The EMR wavelengths may be selected based on one or more criteria described below.

[0049] Determining the wavelengths that are desirable for treating a particular skin condition, such as pigmented and non-pigmented conditions, can depend, for example, on the wavelength-dependent absorption coefficients of various competing chromophores present in the skin (e.g., chromophores, hemoglobin, tattoo ink, etc.). FIG. 7A is a graph of an exemplary absorbance spectrum of melanin. It has been observed that the absorption of EMR by melanin decreases with increasing wavelength after reaching a peak value at a wavelength of about 350 nm. While the absorption of EMR by melanin promotes heating and / or destruction of melanin-containing regions 630, very high melanin absorbance can result in high absorption by pigments in the epidermis 610, reducing the penetration of EMR into the dermis 620 or epidermis 610. As shown in FIG. 7A, melanin absorption at EMR wavelengths less than about 500 nm is relatively high, and as a result, wavelengths less than about 500 nm may not be suitable to penetrate the dermis 620 sufficiently to heat and damage or destroy pigmented regions 630 within the dermis 620. Such enhanced absorption at smaller wavelengths can result in undesired damage to the upper (superficial) portions of the epidermis 610 and dermis 620, with relatively little unabsorbed EMR penetrating the tissue into the deeper portions of the dermis 620.

[0050] FIG. 7B is a graph of an exemplary absorbance spectrum of oxygenated or deoxygenated hemoglobin. Hemoglobin resides in the blood vessels of skin tissue and is either oxygenated (HbO2) or deoxygenated (Hb). Each form of hemoglobin may exhibit slightly different EMR absorption characteristics. As shown in FIG. 7B, the exemplary absorbance spectrum of both Hb and HbO2 shows that at EMR wavelengths less than about 600 nm, the absorption coefficients of both Hb and HbO2 are high, and at higher wavelengths, the absorbance is greatly reduced. Strong absorption of EMR directed to skin tissue by hemoglobin (Hb and / or HbO2) can result in heating of the blood vessels containing hemoglobin, which can cause unnecessary damage to these vascular structures if the desired treatment is a melanin-rich tissue or structure, resulting in less EMR being available for absorption by melanin.

[0051] The selection of an appropriate wavelength for EMR can also depend on the wavelength-dependent scattering profile of the tissues interacting with the EMR. Figure 8 shows a plot of the absorption coefficients of melanin and venous blood versus wavelength. Figure 8 also shows a plot of the scattering coefficient of light versus wavelength in the skin. The absorption of melanin decreases monotonically with wavelength. If melanin is the target of treatment for pigmentation conditions, wavelengths with high melanin absorption are desirable. This suggests that shorter wavelengths of light are more efficient for treatment. However, absorption by blood increases at wavelengths shorter than 800 nm, thus increasing the risk of unintended targeting of blood vessels. In addition, the role of scattering by the skin (e.g., dermal layer) can be important, as the intended target may be located below the skin surface. Scattering reduces the amount of light that reaches the intended target. The scattering coefficient decreases monotonically with increasing wavelength. Thus, shorter wavelengths can favor absorption by melanin, while longer wavelengths can favor deeper penetration due to reduced scattering. Similarly, longer wavelengths are better for protecting blood vessels due to lower absorption by blood.

[0052] With the above considerations in mind, wavelengths may range from about 300 nm to about 3000 nm, more specifically from about 800 nm to about 1064 nm, and may be used to target specific structures (e.g., melanin) in the dermis. In particular, wavelengths of about 800 nm and about 1064 nm may be useful for such treatment. The 800 nm wavelength is attractive because laser diodes at this wavelength are inexpensive and readily available. However, 1064 nm may be useful for targeting deeper lesions because there is less scattering at this wavelength. The 1064 nm wavelength may also be compatible with dark skin types with large amounts of epidermal melanin. In such individuals, the higher the absorption of low wavelength EMR (e.g., about 800 nm) by epidermal melanin, the higher the potential for thermal damage to the skin. Thus, 1064 nm may be a more appropriate wavelength of therapeutic radiation for certain treatments of some individuals.

[0053] A variety of laser sources can be used for EMR generation. For example, neodymium (Nd)-containing laser sources are readily available that provide 1064 nm EMR. Such laser sources can operate in a pulsed mode with repetition rates ranging from about 1 Hz to 100 KHz. Q-switched Nd laser sources can provide laser pulses with pulse durations less than 1 nanosecond. Other Nd laser sources can provide pulses with pulse durations longer than 1 millimeter. An exemplary laser source that provides 1060 nm wavelength EMR is the 20 W NuQ fiber laser from NUFERN, East Granby, Connecticut, USA. The 20 W NuQ fiber laser provides pulses with pulse durations of about 100 ns with repetition rates ranging from about 20 KHz to about 100 KHz. Another laser source is the Nd:YAG Q-smart850 from Quantel, Les Ulis, France. The Q-smart850 provides pulses having a maximum pulse energy of about 850 mJ and a pulse duration of about 6 ns at a repetition rate of up to about 10 Hz.

[0054] The systems described herein can be configured to focus the EMR into a highly focused beam. For example, the systems can include a focusing or focusing lens arrangement having a numerical aperture (NA) selected from about 0.3 to 0.9 (e.g., about 0.4 to about 0.9). The corresponding large focusing angle of the EMR can provide high fluence and intensity at the focal region of the lens (which can be placed within the skin) and low fluence at the overlying tissue above the focal region. Such a focusing geometry helps reduce undesired heating and thermal damage of the overlying tissue above the pigmented skin region. The exemplary optical array may further include a collimating lens array configured to direct the EMR from the emitting array to the focusing lens array.

[0055] An exemplary optical therapy system may be configured to focus EMR into a focal region having a width or spot size of less than about 200 μm, e.g., less than about 100 μm, or less than about 50 μm, e.g., about 1 μm. For example, the spot size may range from about 1 μm to about 50 μm, about 50 μm to about 100 μm, and about 100 μm to about 200 μm. The spot size of the focal region may be determined, for example, in air. Such spot size may be selected to be small enough to provide a high fluence or intensity of EMR at the focal region (to effectively irradiate pigmented structures in the dermis) and large enough to facilitate irradiation of a large area / volume of skin tissue in an appropriate treatment time.

[0056] Exemplary optical arrangements may also be configured to direct the focal region of EMR to a location within dermal tissue at a depth below the skin surface, for example, in a range of about 30 μm to about 2000 μm (e.g., between about 150 μm to about 500 μm). Such exemplary depth ranges may correspond to typical observed depths of pigmented areas of skin indicative of dermal melasma or other targets of interest. This focal depth may correspond to a distance from a lower surface of the device configured to contact the skin surface and a location of the focal region. Additionally, some embodiments may be configured to treat targets within the epidermis. For example, the optical arrangement may direct the focal region of EMR to ... For example, the optical device may be configured to direct the EMR focal region to a location within the epidermal tissue, for example, in a range of about 5 μm to 2000 μm below the skin surface. Other embodiments may be configured to treat targets deep within the dermis. For example, tattoo artists typically adjust their tattoo guns to penetrate the skin to a depth of about 1 mm to about 2 mm below the skin surface. Thus, in some embodiments, the optical device may be configured to direct the EMR focal region to a location within the dermal tissue, for example, in a range of about 0.4 mm to 2 mm below the skin surface.

[0057] [Example] Figure 9A shows multiple plots illustrating the cooling performance of multiple exemplary cooling elements (e.g., the cooling elements of Figures 9B-9D). The data shown in Figure 9A was collected during tests conducted with cooling elements 920, 930, and 940. Graph 900 plots temperature in degrees Celsius along vertical axis 910 and time (in minutes and seconds) along horizontal axis 912.

[0058] Each cooling element was placed on a test fixture block and a thermocouple was placed in the center of the first surface of the cooling element. Thermal grease was used to ensure thermal transfer between the first surface of the cooling element and the thermocouple. The cooling elements were placed so that their first surface was in contact with the dry bath. The dry bath was set to 37°C and each cooling element was allowed to approach thermal equilibrium with the dry bath. Finally, 5°C cooling fluid was provided to the cooling elements and the thermocouple took temperature measurements of the first surface as the window cooled.

[0059] 9B-9D show schematic diagrams of exemplary cooling elements tested as part of the above experiments. Exemplary embodiments of the cooling elements are a first single window type cooling element 920, a second single window type cooling element 930, and a double window type cooling element 940. FIG. 9B shows a single window type cooling element 920 including a single sapphire window 922 in contact (e.g., along an edge of the sapphire window) with an aluminum heat exchanger 924 through which coolant 926 flows. Heat flows from the dry bath 928 to the center of the first surface of the sapphire window 922 (e.g., the surface adjacent to the dry bath 928), through the sapphire window 922 to the edge of the sapphire window 922, and through the aluminum heat exchanger 924 to the coolant 926. The temperature of the first surface of the window 922 is measured by a thermocouple 929.

[0060] 9C shows a single window type cooling element 930 including a single sapphire window 932 sealed to a manifold 934 through which a coolant 936 flows. The single window type cooling element 930 is configured such that the coolant 936 is in direct contact with the single sapphire window 932 around the edge of the window 932. Heat flows from the dry bath 938 to the center of a first surface of the window 932 (e.g., the surface adjacent to the dry bath 938) and through the edge of the window 932 directly to the coolant 936. The temperature of the first surface of the window 932 is measured by a thermocouple 939.

[0061] 9D shows a double window type cooling element 940 including a first window 942, a second window 943, a frame 944, and a coolant 946 flowing between the first window 942 and the second window 943. Heat flows from the dry bath 948 to the center of a first surface of the first window 942 (e.g., the surface adjacent to the dry bath 948) and flows vertically through the first window 942 to the coolant 946. The temperature of the first surface of the first window 942 is measured by a thermocouple 949.

[0062] Returning to FIG. 9A, cooling data for cooling elements 920, 930, and 940 are shown. A first set of plots (920A-D) show cooling data for a first single window type cooling element 920, a second set of plots (930A-B) show cooling data for a second single window type cooling element 930, and a third plot 940A shows cooling data for a double window type cooling element 940. The plots show improved cooling for the second single window type cooling element 930 over the first single window type assembly 920. However, the double window type cooling element 940 shows improved cooling compared to the first and second single window types. 9C. The graph 900 also shows that cooling occurs faster when using the dual pane type cooling element 940. The thermal time constant for the first and single pane type assemblies (e.g., the time for the window to cool to about 63.2% of its initial temperature) is estimated based on the data to be about 4 seconds, and the thermal time constant for the dual pane type assembly is estimated to be about 2 seconds, or half that of the single pane type assembly.

[0063] Methods for treating various skin conditions, such as for cosmetic purposes, can be performed using the systems described herein. Such methods can be performed by a physician, although it will be appreciated that non-physicians, such as aestheticians and other appropriately trained personnel, can use the systems described herein to treat various skin conditions, with or without medical supervision.

[0064] Those skilled in the art will appreciate further features and advantages of the present invention based on the above-described embodiments. Accordingly, the present invention is not limited to what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

[0065] The subject matter described herein can be implemented in digital electronic circuitry, or computer software, firmware, or hardware, including the structural means disclosed herein and their structural equivalents, or combinations thereof. The subject matter described herein can be implemented in one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., a machine-readable storage device) or embodied in a propagated signal for execution by or control of the operation of a data processing device (e.g., a programmable processor, a computer, or various computers). Computer programs (also referred to as programs, software, software applications, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be distributed in any form, including as standalone programs or as modules, components, subroutines, or other devices suitable for use in a computing environment. A computer program does not necessarily correspond to a file. A program may be stored as part of a file that holds other programs or data, in a single file or in multiple coordinated files dedicated to the program (e.g., a file that stores one or more modules, subprograms, or code portions). A computer program may be distributed to be executed on one computer, or on multiple computers at a single site, or distributed across multiple sites and interconnected by a communications network.

[0066] The processes and logic flows described herein, including steps of the methods of the subject matter described herein, may be performed by one or more programmable processors that execute one or more computer programs to operate on input data and generate output to perform the functions of the subject matter described herein. The processes and logic flows may be performed by special purpose logic circuitry, such as, for example, an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). Apparatus of the subject matter described herein may also be implemented as special purpose logic circuitry, such as, for example, an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0067] Processors suitable for executing a computer program include, for example, both general purpose and special purpose microprocessors, and any one or more processors of any kind of digital computer. Typically, a processor receives instructions and data from a read-only memory or a random access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer also includes and is operatively coupled to receive data from, transmit data to, or both of, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks. Information media suitable for embodying computer program instructions and data include all forms of non-volatile memory, including, for example, semiconductor storage devices (e.g., EPROM, EEPROM, and flash memory devices), non-volatile memory magnetic disks (e.g., internal hard disks or removable disks), magneto-optical disks, and optical disks (e.g., CD and DVD disks). The processor and memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0068] To provide interaction with a user, the subject matter described herein may be implemented on a computer having, for example, a computer display device, a CRT (cathode ray tube) or LCD (liquid crystal display) monitor for displaying information to the user, a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input. Other types of devices may also be used to provide interaction with a user. For example, feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user may be received in any form, including acoustic, speech, or tactile input.

[0069] The techniques described herein may be implemented using one or more modules. As used herein, the term "module" refers to computing software, firmware, hardware, and / or various combinations thereof. However, at a minimum, a module should not be interpreted as software that is not implemented in hardware, firmware, or recorded in a non-transitory processor-readable recordable storage medium (i.e., a module is not software itself). In fact, a "module" is always interpreted to include at least some physical non-transitory hardware, such as a processor or part of a computer. Two different modules can share the same physical hardware (e.g., two different modules can use the same processor and network interface). The modules described herein may be combined, integrated, separated, and / or replicated to support different applications. Also, functions described herein by being performed in a particular module may be performed by one or more other modules and / or by one or more other devices instead of or in addition to functions performed in the particular module. Also, modules may be implemented locally or remotely across different devices and / or other components. Also, modules may be moved from one device and added to another device, or included in both devices.

[0070] The subject matter described herein may be implemented in a computing system that includes back-end components (e.g., a data server), middleware components (e.g., an application server), or front-end components (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described herein), or a combination of such back-end, middleware, and front-end components. The components of the system may be interconnected by any form or medium of digital data communication, e.g., a communications network. Examples of communications networks include local area networks ("LANs"), local area networks ("LANs"), and the like. ") and wide area networks ("WANs") (e.g., the Internet).

[0071] Approximation language used throughout the specification and claims of this specification may be applied to modify any quantitative expression that may be permissibly changed without resulting in a change in the basic function involved. Thus, values ​​modified by one or more terms such as "about" and "substantially" should not be limited to the exact value specified. In at least some instances, approximation language may apply to the precision of the instrument for measuring the value. Throughout the specification and claims, range limitations may be combined and / or interchangeable, and such ranges are identified and include all subranges contained therein, unless otherwise indicated by context or language.

Claims

1. 1. A system comprising: an optical element configured to receive electromagnetic radiation (EMR) and focus the EMR along an optical axis to a target focal region; a controller configured to guide the focal region along the target path; a cooling element for cooling the down beam from the optical element, the cooling element being removably mounted to the system via three or more datums and configured to receive the focused EMR; The cooling element comprises: a first window including a first proximal surface and a first distal surface; a second window down beam from the first window, the second window including a second proximal surface and a second distal surface, the second window configured to contact the target or an object adjacent to the target through the second distal surface, the path being parallel to the second distal surface in a range of 100 milliradians to 0.001 milliradians; a coolant chamber disposed between the first distal surface of the first window and the second proximal surface of the second window and configured to receive a coolant; Including, system.

2. 2. The system of claim 1, wherein the controller is configured to vary a first distance between the focal region and the second distal surface of the second window along the optical axis by varying a second distance between the optical element and the second distal surface of the second window along the optical axis.

3. The system of claim 2 , wherein the first distance varies between a first predetermined value and a second predetermined value as the focal region traverses along the path of the target.

4. 4. The system of claim 3, wherein the difference between the first and second predetermined values ​​is less than 0.25 mm.

5. 3. The method according to claim 2, wherein the first predetermined value is 0.001 mm and the second predetermined value is 10 mm. The system described in

6. 2. The system of claim 1, wherein the controller is configured to vary a first distance between the focal region and a second distal surface of the second window along the optical axis by varying a divergence associated with EMR.

7. The system of claim 1 , further comprising a scanning device, the scanning device configured to receive control signals from the controller and to move the focal region along a treatment path based on the control signals.

8. The system of claim 1 , wherein the controller is configured to vary an intensity of EMR.

9. The system of claim 1 , wherein the controller is configured to vary a flow rate of the coolant in the coolant chamber.

10. The system of claim 1 , wherein the optical element has a numerical aperture (NA) in the range of 0.1 to 1.

0.

11. The system of claim 1 , wherein the EMR has an average power in the range of 1 W to 100 W.

12. The system of claim 1 , wherein the EMR comprises a pulsed laser beam having a wavelength in the range of 400 nm to 4000 nm.

13. The system of claim 1 , wherein the EMR is configured to generate a thermionic plasma at the focal region.

14. The system of claim 1 , further comprising a gas source configured to direct a gas at a first window, the gas configured to prevent condensation on the first window.

15. The system of claim 1 , wherein the first window has a first thermal effusivity and the second window has a second thermal effusivity greater than the first thermal effusivity.

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