WO2024092221A1

WO2024092221A1 - Beam shaping apparatus for laser beams

Info

Publication number: WO2024092221A1
Application number: PCT/US2023/078065
Authority: WO
Inventors: Rajender Katkam; Jayant Bhawalkar
Original assignee: Avava, Inc.
Priority date: 2022-10-27
Filing date: 2023-10-27
Publication date: 2024-05-02

Abstract

Monolithic optical elements, optical elements, and methods associated therewith are provided. The monolithic optical element includes a body a body extending between a first side and a second side. The body is configured to receive a diverging non-uniform fluence beam at the first side from a laser source, collimate and shape the received diverging non-uniform fluence beam between the first side and the second side, and emit a shaped and collimated beam from the second side. The emitted shaped and collimated beam has an at least partially annular transverse energy profile.

Description

BEAM SHAPING APPARATUS FOR LASER BEAMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/419,741, filed October 27, 2022, and entitled “BEAM SHAPING APPARATUS FOR LASER BEAMS,” which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Presently a number of energy-based devices are available for fractionated treatment of the dermis. These methods include ablative lasers, non-ablative lasers, micro-needling, and RF energy treatments. Generally, these presently available fractionated energy-based treatments require damage to outer portions of skin undergoing treatment (e.g., epidermis). Damage to the epidermis, in most cases, causes the skin to appear inflamed, blemished, or unhealthy immediately after treatment. Additionally, severe damage to the epidermis can lead to one or more of infection and a need for additional medical treatment. This undesirable appearance results in a post-treatment downtime that lasts until the epidermis has healed, which may take days to weeks depending on treatment parameters used (e.g., ablative vs. non-ablative). Most patients do not return to their normal lives until after the post-treatment down-time. It is therefore desirable that a fractionated treatment system and method be made available, which can successfully affect the dermis while minimizing damage to the epidermis in order to minimize post-treatment downtime.

SUMMARY

[0003] Skin rejuvenation is often performed through fractional treatment. Fractional or fractionated energy-based treatment refers to a treatment in which only a fraction of an area of tissue is exposed to energy. For example, a fractional skin treatment may treat 25% of an area of skin with a laser beam and leave a remaining 75% of skin in that area untreated. Energy-based skin rejuvenation involves creating controlled small injury within a collagen network. The small injury causes a wound healing process in which new collagen is formed. The newly formed collagen tightens the skin, thereby causing the skin to appear more youthful. Many skin rejuvenation fractionated treatment systems work by targeting water as a chromophore achieving photothermolysis. [0004] Fractionated treatment can generally be divided into two categories: ablative and nonablative. Ablative treatment causes removal of tissue and results in superficial micro-injury in addition to creating thermal damage within the dermis. Non-ablative treatment typically does not cause tissue removal, instead causing only thermal disruption. An advantage of non-ablative fractionated treatment over ablative fractionated treatment is a reduction in down-time.

[0005] Energy-based fractionated treatment of tissue generally requires that a high amount of energy be delivered to and absorbed by a selective portion of tissue to effect a desired disruption or damage. This disruption or damage is repeated over an area of tissue, so that small regions (e.g., about 0.1 to about 10 mm in diameter) of disrupted tissue are interlaced with undamaged tissue. The small regions of damaged tissue are then replaced with new tissue during a posttreatment healing process. Inducing damage within a dermis layer of skin while minimizing damage to an overlying epidermis layer presents a number of technical challenges, some of which are enumerated below.

[0006] First, there is no known chromophore within the dermis layer of tissue which is not present within the epidermis layer of tissue. This means that a radiation selected to absorb within the dermis will also be absorbed within the epidermis layer.

[0007] Second, as the electromagnetic radiation (EMR) will be equally well absorbed by the epidermis layer and the dermis layer of the skin, a greater energy density must be delivered to the dermis layer than to the epidermis. In order to achieve this, the EMR profile must be varied, such that a focal region (i.e., region of maximum energy density) of the EMR beam is located within the dermis and only an unfocused region (i.e., region of minimum energy density) of the EMR beam impinges on the epidermis layer of the skin.

[0008] Third, skin tissue is a turbid medium, meaning that radiation propagating through skin scatters. The scattering of radiation within skin tissue, makes it more difficult to form a focal region (region of maximum energy density) at any depth within the tissue, compounding the first and second challenges above.

[0009] Fourth, the focal region (or region of maximum energy density) must be accurately positioned at a depth within the dermis layer of the skin. This ensures that the region of maximum energy density is located in the dermis and not located within the epidermis, in order to prevent unwanted damage to the epidermis. [0010] Fifth, the EMR beam is delivered from outside the tissue; and, therefore, the epidermis experiences some minimal irradiation and minor thermal heating (i.e., less than the dermis). In response to this fifth challenge, the epidermis layer directly overly the dermis layer being treated must be actively cooled to prevent thermal damage to the epidermis.

[0011] Therefore, to provide fractionated therapeutic disruption to the dermis layer of a skin tissue, while minimizing damage to overlying epidermal layers, a need exists for fractionated treatment systems and methods that address all of the above-mentioned challenges.

[0012] Monolithic optical elements are provided. For example, in an embodiment, a monolithic optical element is provided, including a body extending between a first side and a second side. The body can be configured to receive a diverging non-uniform fluence beam at the first side from a laser source, collimate and shape the received diverging non-uniform fluence beam between the first side and the second side, and emit a shaped and collimated beam from the second side. The emitted shaped and collimated beam can have an at least partially annular transverse energy profile.

[0013] The embodiment can vary in a number of ways. For example, in some variations, the emitted shaped and collimated beam can have a radially symmetric energy profile, which can be configured to produce MTZs in tissue having a substantially annular shape. In other variations, the emitted shaped and collimated beam can have a radially asymmetric energy profile, which can be configured to produce MTZs in tissue having a substantially crescent shape. In further variations, the body can be configured to emit a shaped and collimated beam having various distributions, including a top hat irradiance distribution and a step irradiance distribution. The body can include a first convex facet disposed at the first end and a second concave facet disposed at the second end. The first convex facet can define an entrance aperture of the body. In still further variations, the body can include at least two facets covered in a high-reflectivity coating or at least two facets covered in an anti -reflectivity coating.

[0014] In another embodiment, an optical arrangement is provided, including a laser source and a compact monolithic optical element. The compact monolithic optical element can include a first side defining an entrance aperture and a second side having an at least partially convex facet, with the first side being opposite the second side. The compact monolithic optical element can be configured to receive a diverging beam from the laser source via the entrance aperture and emit a collimated and shaped beam having an at least partially annular energy profile. [0015] The optical arrangement can vary in a number of ways. For example, the laser source and the compact monolithic optical element can be arranged in-line on an optical axis, and the at least partially annular energy profile can be fully annular. In another example, at least one of the laser source and the compact monolithic optical element are skew relative to an optical axis of the optical arrangement. The skew can be a rotation relative to the optical axis or a translation relative to the optical axis. In some variations, the at least partially annular energy profile can be radially asymmetric. In another example, the compact monolithic optical element is configured to internally reflect the received diverging beam at least twice prior to emission. In a further example, the compact monolithic optical element can be configured to collimate and shape the received diverging beam within internal reflection.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Embodiments of the disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0017] FIG. 1 A is a diagram of an optical arrangement according to an embodiment;

[0018] FIG. IB is an irradiance distribution produced by the optical arrangement of FIG. 1 A;

[0019] FIG. 2A is a diagram of an optical arrangement with a pair of decentered axicons according to an embodiment;

[0020] FIG. 2B is an irradiance distribution produced by the optical arrangement of FIG. 2 A;

[0021] FIG. 3 A is a diagram of a compact monolithic optical element according to an embodiment;

[0022] FIG. 3B is a graph of a Gaussian irradiance distribution;

[0023] FIG. 3C is an irradiance distribution produced by the optical arrangement of FIG. 3 A

[0024] FIG. 3D is a diagram of the compact monolithic optical element of FIG. 3 A with a modified facet to produce asymmetric beams;

[0025] FIG. 3E is an irradiance distribution produced by the optical arrangement of FIG. 3D

[0026] FIG. 4A is a manufacturer-friendly compact monolithic optical element according to an embodiment; [0027] FIG. 4B is an irradiance distribution produced by the optical arrangement of FIG. 4 A;

[0028] FIG. 4C is a graph of a cross-section of the irradiance distribution of FIG. 4B;

[0029] FIG. 4D is a diagram of optical element of FIG. 4A with a modified facet to produce an asymmetric beam;

[0030] FIG. 4E is an irradiance distribution produced by the optical arrangement of FIG. 4D;

[0031] FIG. 4F is a graph of a cross-section of the irradiance distribution of FIG. 4E;

[0032] FIG. 5A is a diagram of a compact monolithic optical element according to an embodiment;

[0033] FIG. 5B is a graph of a Gaussian irradiance distribution;

[0034] FIG. 5C is an irradiance distribution produced by the optical arrangement of FIG. 5 A;

[0035] FIG. 5D is a graph of a cross-section of the irradiance distribution of FIG. 5C;

[0036] FIG. 5E is an optical arrangement including the optical element of FIG. 5A rotated relative to the optical axis;

[0037] FIG. 5F is an irradiance distribution produced by the optical arrangement of FIG. 5E;

[0038] FIG. 5G is a graph of a cross-section of the irradiance distribution of FIG. 5F;

[0039] FIG. 6A is a diagram of a compact monolithic optical element according to an embodiment;

[0040] FIG. 6B is an irradiance distribution produced by the optical arrangement of FIG. 6 A;

[0041] FIG. 6C is a graph of a cross-section of the irradiance distribution of FIG. 6B;

[0042] FIG. 6D is an optical arrangement including the optical element of FIG. 6A rotated relative to the optical axis;

[0043] FIG. 6E is an irradiance distribution produced by the optical arrangement of FIG. 6D;

[0044] FIG. 6F is a graph of a cross-section of the irradiance distribution of FIG. 6E; [0045] FIG. 7A is an image of en face Nitro Blue Tetrazolium Chloride (NBTC) stained histology of human ex-vivo abdominoplasty skin treated with a symmetric ring beam;

[0046] FIG. 7B is an image of en face NBTC stained histology of human ex-vivo abdominoplasty skin treated with an asymmetric ring beam;

[0047] FIG. 7C is an image of MENDS on skin taken three days after treatment with a symmetric ring beam; and

[0048] FIG. 7D is an image of MENDS on skin taken three days after treatment with an asymmetric ring beam.

[0049] It is 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 disclosure. The systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments.

DETAILED DESCRIPTION

[0050] Certain exemplary embodiments will now be described to provide an overall 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. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. 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 disclosure.

[0051] Embodiments of the disclosure are discussed in detail below with respect to fractionated treatment including skin rejuvenation and skin resurfacing, for example skin resurfacing for: acne, chickenpox and surgical scars, periorbital and perioral wrinkles, photoageing changes, facial dyschromias, and stretch marks. Additional treatments related to the disclosure include treatment of pigmentary conditions of the skin, such as melasma, and other pigmentary conditions, such as granuloma annulare. [0052] The disclosed embodiments can be employed for treatment of other pigmentary and non- pigmentary conditions and other tissue and non-tissue targets without limit. Examples of pigmentary conditions can include, but are not limited to, post inflammatory hyperpigmentation (PIH), dark skin surrounding eyes, dark eyes, cafe au lait patches, Becker’s nevi, Nevus of Ota, congenital melanocytic nevi, ephelides (freckles) and lentigo. Additional examples of pigmented tissues and structures that can be treated include, but are not limited to, hemosiderin rich structures, pigmented gallstones, tattoo-containing tissues, and lutein, zeaxanthin, rhodopsin, carotenoid, biliverdin, bilirubin and hemoglobin rich structures. Examples of targets for the treatment of non-pigmented structures, tissues and conditions can include, but are not limited to, hair follicles, hair shafts, vascular lesions, infectious conditions, sebaceous glands, acne, and the like.

[0053] Methods of treating various skin conditions, such as for cosmetic purposes, can be carried out using the systems described herein. It is understood that, although such methods can be conducted by a physician, non-physicians, such as aestheticians and other suitably trained personnel may use the systems described herein to treat various skin conditions with and without the supervision of a physician.

[0054] Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Sizes and shapes of the systems and devices, and the components thereof, can depend at least on the anatomy of the subject in which the systems and devices will be used, the size and shape of components with which the systems and devices will be used, and the methods and procedures in which the systems and devices will be used.

[0055] The spatial intensity profile of a laser beam often has a Gaussian distribution. However, it has been demonstrated that the use of a ring-or doughnut-shaped beam profile, at wavelengths that are absorbed by water, focused into skin can reduce the epidermal injury to the skin while maximizing the volume of injury in the dermis. Non-limiting embodiments of treatment systems and methods employing ring- or doughnut-shaped beam profiles are discussed in detail in U.S. Patent Application No. 17/094,394, entitled “Feedback Detection For A Treatment Device”, the entirety of which is incorporated by reference.

[0056] The focused ring-shaped beam of light can be thought of as a hollow cone of light. Notably, histology of tissue treated with such ring-shaped beams shows a characteristic conical injury in the skin, while leaving tissue in the center of the cone and outside the cone unaffected. When this configuration is used with a high peak power laser at a wavelength that is absorbed by melanin, selective destruction of melanin can be achieved at the apex of the cone while minimizing collateral damage. Certain treatment procedures relying on fractionated treatment can make use of a variety of beam shapes in order to more effectively treat the above-described maladies. During such treatment procedures, a laser beam of optical energy is directed toward a target tissue, such as skin, in order to introduce a desired dose of optical energy to that target tissue to treat one or more ailments, such as those described above. The optical energy creates treatment areas known as micro-thermal zones (MTZs) of damage in a pattern or array. The delivery of too much optical energy can cause harm to the patient, while the delivery of too little optical energy can lead to an ineffective treatment. For example, the maladies described above can require energies from 1 pj to 250 mJ, and depth of treatments can range from about -500 pm to 2cm (where the origin is defined at the surface of the tissue) into the tissue being treated, where the negative treatment depth is achieved by focusing the energy at a corresponding distance above the surface of the tissue.

[0057] Further, it is known that creating MTZs having various shapes can provide certain benefits, including increasing an effectiveness of the treatment procedure when compared to treatments involving MTZs of different shapes, even when a total amount of energy is held constant. For example, the use of a focused transverse annular (ring-like) laser beam for treatment of skin can be more effective than a solid laser beam of otherwise-equivalent properties. With a beam having a transverse annular energy profile treats skin tissue, MTZs having an annular or ring-like shape can be created on the target tissue. The benefit of using an annular ring to create annular MTZs when compared to a solid beam is that the undamaged tissue at the center of the annular MTZs can lead to reduced healing times of the coagulated tissue because healing can occur both from the outside of the MTZ inward and from the inside of the MTZ outward. In contrast, a solid circular MTZ resulting from a solid beam amounts to a larger total volume of damaged tissue, as compared to an MTZ from an annular beam, and the solid circular MTZ only allows for healing from the outside inward. The promotion of healing from an annular MTZ can decrease adverse side effects resulting from a treatment with an annular beam, and additional optical energy can potentially be delivered to an afflicted tissue area without resulting in harm that would otherwise befall a treatment procedure using a solid beam.

[0058] A beam having a transverse annular energy profile can be created in a number of ways, including by using a pair of axicons. An example of an existing optical system 10 configured to generate a ring-shaped beam 20 is illustrated in FIG. 1 A. The output from an optical fiber 12 is a divergent beam 14A (diverging rays), and is directed to a collimator 16 to create a collimated beam 14B (parallel rays). As illustrated in FIG. 1 A, the collimated beam 14B is directed to an axicon pair 18A, 18B (e.g., a pair of conical prisms) to convert the collimated beam 14B to a collimated ring geometry 14C (also called a shaped beam 14C) having a transverse annular energy profile. The shaped beam 14C has an outer diameter DI and an inner diameter D2 that together define the ring-shape of the shaped beam 14C. When viewed straight on, the shaped beam 14C has an energy distribution like the kind depicted in the graph 20 as shown in FIG. IB, where the distribution of energy is lower toward the outer diameter DI as opposed to the inner diameter D2.

[0059] While the advantages realized by a beam having a transverse annular energy profile are significant, especially when compared to solid beams, laser beams having an asymmetric energy distribution can have an added benefit beyond even that which is seen in the annular beams. The MTZs created by annular beams can result in a ring-like shape of damaged tissue, as explained above. However, in some percentages of annular MTZs, the undamaged tissue region at the center of the MTZ can become nutritionally isolated from the patient’s body by the surrounding coagulated tissue, and the untreated tissue may not survive. This results in a loss of the outward healing described above for that MTZ. In contrast, laser beams having an asymmetric energy distribution can create MTZs having an annular or semi-annular shape, such as crescents, semicircles, ellipses, and elliptical rings, among others, which have an identifiable central region but that are much less likely (or never) to be isolated from the patient’s body located outside the MTZ. This means that for MTZs created by an asymmetric beam, the added healing benefits described above are attained but without the added risk of the loss of the untreated central tissue. Essentially, the asymmetric energy distribution can result in MTZs surrounded by a completely contiguous tissue region.

[0060] Asymmetric MTZs can be created using a number of methods, including specially- designed optical elements, deliberate arrangements of optical elements, and combinations thereof. One example, depicted in FIG. 2 A, depicts a similar setup as depicted in FIG. 1 A except that the optical arrangement 10' of FIG. 2A produces asymmetric MTZs. Just as with the optical arrangement 10, the optical arrangement 10' includes a laser source 12' to emit an unshaped and uncollimated beam 14 A', a collimator 16' to turn the beam 14 A' into a collimated beam 14B', and pair of axicons 18A', 18B' to shape the collimated beam 14B' into a collimated and shaped beam 14C' having a transverse annular energy profile. The asymmetry, where the optical arrangement 10' differs from the optical arrangement 10, is achieved by decentering the pair of axicons 18 A', 18B' relative to a central optical axis X such that the pair of axicons 18 A', 18B' are translated as compared to the pair of axicons 18A, 18B featured in the arrangement of FIG. 1A. This translation results in the energy distribution pattern 20' seen in FIG. 2A, where the overall shape of the pattern 20' is annular, but only the lower portion of the pattern 20' is of a higher energy. When a beam having an energy distribution pattern like the pattern 20' treats a tissue, the resulting MTZ will be crescent shaped because the portion of the beam corresponding to the upper portion of the pattern does not carry enough energy to coagulate tissue. This crescentshaped region R is depicted in FIG. 2B.

[0061] Despite certain practical applications and benefits of the above-described designs, these optical configurations can be unsuitable for space-constrained applications, such as in hand-held portable devices. Notably, an optical arrangement such as the optical arrangement 10 illustrated in FIG. 1 A involves multiple elements (e.g., collimator, axicon pair, etc.) and can be several centimeters in length, possibly exceeding or straining available space in such space-constrained applications. For most therapeutic applications, the laser fluence (peak power per unit focal spot area) across the ring radially should approximately constant. However, the intensity distribution in the ring-shaped beam formed by an optical system such as that of FIG. 1 A is not uniform, as evidenced by the distribution depicted in the graph 20 of FIG. IB. Instead, the intensity of the distribution is highest at the inner diameter of the ring and decreases moving towards the outer diameter. Additionally, having multiple optical elements can require time-consuming alignment steps for optimal performance, as each

[0062] While a pair of axicons like the pair of axicons 18A, 18B of FIG. 1A can provide one way in which to form a collimated beam having an asymmetric transverse annular energy profile, other optical elements may be used in place of or in addition to the pair of axicons.

[0063] FIGS. 3A-3E, for example, depict embodiments of monolithic optical elements that can both collimate and shape an incident beam into a beam having a transverse annular energy profile. The optical elements depicted can further transform a Gaussian laser beam having a distribution like the kind featured in FIG. 3B into a beam having a transverse annular energy profile with a variety of irradiance distributions. While the variety of optical elements can produce the various distributions depicted herein, a given optical element can be tailored as much or as little as needed so as to produce a specific distribution. Accordingly, the examples and variations provided herein are illustrative only, and are not limiting.

[0064] In general, these kinds of monolithic optical elements present a single-element beam shaper that transforms a diverging output from an optical fiber or other energy source into a collimated ring beam having a uniform intensity profile. This monolithic optical element can have several advantages over other geometries that make it suitable for situations including space-constrained applications like the kind described above, including: (1) compact size, (2) uniform beam profile in a collimated output ring beam, and (3) no need for alignment.

[0065] The monolithic optical element 100 includes a body 110 extending between a first end 112 and a second end 114. The first end 112 (e.g., the left end as depicted in FIG. 3 A) of the body 110 includes a first facet SI, and the second end 114 (e.g., the right side as depicted in FIG. 3 A) of the body 110 includes a second facet S2 and a third facet S3. A combination of facet geometry and reflective and transmissive portions of the facets SI, S2, S3 achieve a collimated beam having a transverse annular energy profile.

[0066] The first facet SI is shown having generally curved shape with a protruding mid-region protruding outward therefrom. In some implementations, the first facet SI can be coated with a high-reflectivity coating (e.g., greater than about 80%, greater than about 85%, greater than about 90%, greater than about 85%, greater than about 98%) everywhere except for an entrance aperture 120. The mid-region forms an entrance aperture 120 into which a laser beam from a laser source 130 (e.g., an optical fiber or the like) can be directed. The entrance aperture 120 is a small anti-reflection coated region with a diameter at least as large as the diameter of the laser beam exiting the laser source 130. For a single-mode fiber, this diameter can be as small as 6 pm and can be as large as the inner diameter of the desired ring shape of the output collimated ringshaped laser beam B3. The performance of the optical element 100 does not depend strongly on the diameter of the anti -refl ection coated region within the limits described above. The second facet S2 and the third facet S3 can have different geometric shapes. The second facet S2 can be positioned radially inward of the third facet S3 and can be coated for high-reflectivity. The third facet S3 is contiguous with the second facet S2 but is an approximately flat surface. [0067] The first and second facets SI and S2 are shaped according to certain rules. The second facet S2 can receive a diverging laser beam incident upon the optical element 100 that has a non- uniform radial fluence distribution (Gaussian distribution), referred to herein as diverging non- uniform fluence beam Bl. This Gaussian distribution can be seen in the graph 140 of FIG. 3B, which has some general width W. While the optical element 100 is described as converting a Gaussian diverging beam to a collimated ring-shaped beam with a substantially uniform fluence, embodiments of the disclosure are applicable to an input beam with any arbitrary fluence distribution. The second facet S2 can have a shape configured to transform the diverging non- uniform fluence beam Bl, upon reflection, to a beam that has a uniform radial fluence distribution but is not collimated, referred to herein as uniform fluence non-collimated beam B2. The facet SI has a shape configured to transform the uniform fluence non-collimated beam B2, upon reflection, to a uniform fluence collimated ring-shaped beam B3. The third facet S3 can be approximately flat such that the uniform fluence collimated ring-shaped beam B3 passes through the third facet S3 substantially unaltered and emerges as the output collimated ring-shaped beam with an energy distribution similar to the kind shown in the graph 150 depicted in FIG. 3C. The distribution shown in the graph 150 has a higher energy density located toward an outer diameter of the distribution as compared to an inner diameter, although modifications to the monolithic optical element 100 could be made to result in varying distributions, as will be described herein. Further, it can be observed that the fluence is roughly constant in the radial direction of the graph 150, which represents a significant improvement in radial fluence uniformity as compared to ring-shaped beams generated by existing optical systems such as that of FIG. IB. Ultimately, the optical element 100 is but one element that can be used to collimate and shape a laser beam into a collimated laser beam having a transverse annular ring profile.

[0068] The optical element 100 is one kind of optical element that can be used to collimate and shape a laser beam. In general, the shapes of the first and second facets SI, S2 can be given by the following equations:

[0071] These equations provide general description for optical surfaces having aspheric profiles, where Eq. 1 describes an odd-polynomial and Eq. 2 describes an even polynomial. In the equations, z is the sagitta (sag) of the surface, which represents a deviation from a y-axis, r is the radial position of the ray intercept on the surface, k is the conic constant as measured at the vertex where r is zero, c is the reciprocal of the radius of curvature of the base sphere of the surface, p is r/r_max (radius normalized to the max aperture) and ai are the coefficients of the polynomial.

[0072] The monolithic optical element 100 is also suitable to create asymmetric beam geometries, and asymmetric MTZs, like the kind described herein. This can be accomplished in a number of ways, including by directly modifying the facets of the optical element 100 itself so that, for example, the entrance aperture 120 is skewed to one side or another, the facets SI, S2, S3 are modified to have different lengths, shapes, or angles, or a combination of such modifications. Further, by manipulating a position and/or orientation of the laser source 130 relative to the monolithic optical element 100, or vice versa, a similar effect can be achieved. FIG. 3D depicts an example of such a manipulation. In this example, the monolithic optical element 100' is identical to the monolithic optical element 100, and the laser source 130' is identical to the laser source 130 except that the laser source 130' has been tilted at an angle equal of about 0.1 degrees relative to the optical axis. This tilt produces an asymmetric irradiance distribution, which is depicted in the graph 160 of FIG. 3E. The asymmetric irradiance distribution of FIG. 3E is more drastically weighted to the lower region of the annular distribution, and this kind of distribution would produce MTZs having a partially annular and/or crescent-like shape, as described above. While the sharpness of the distribution in the graph 160 is greater than that of FIG. 2B, for example, this could be modified by manipulating the form and/or position of the optical element 100' and/or the position of the laser source 130'.

[0073] As explained above, the specific design of the optical element can vary, and desired effects can be produced as a result of the varied design. Further, the same or similar effects can be produced with various designs. In another embodiment, described with reference to in FIGS. 4A-4F, optical elements are depicted that are similar to optical element 100 but with a design that is easier to fabricate or manufacture. FIG. 4A depicts optical element 200, which is a compact monolithic optical element that is able to collimate and shape a beam, similar to the optical element 100. For brevity, features of optical element 200 that are similar to optical element 100 will not been described again. The optical element 200 includes facets SI', S2', S3', which are all generally more smooth and regular as compared to the facets SI, S2, S3 of optical element 100. For example, the facet SI' is substantially defined by a single curve, and the facets S2', S3' are substantially defined by a single surface. This stands in contrast with the facets SI, S2, which require more complex geometries. The optical element 200 is designed to both shape and collimate a beam received from a laser source 230, similar to the previously described optical elements, which can result in the creation of an irradiance distribution like the kind depicted in that of FIG. 3C.

[0074] Similar to optical element 100, the form of optical element 200 can be described with Eq. 1 and Eq. 2 with data provided in each of Tables 1 and 2.

Table 1

Table 2

[0075] As explained above, optical elements can be tailored to produce a beam having a transverse annular energy profile with a given irradiance distribution as desired. For example, the optical element 200 of FIG. 4 A can be used to create the distribution 220 of FIG. 4B, which differs from the distribution of FIG. 3C in that the energy is the same for any given sampled unit area except in the center of the ring. The distribution 250 of FIG. 4C shows irradiance levels taken at a cross-section of the distribution 220 of FIG. 4B along the x-axis, where irradiance levels to the left and the right of the center region of the distribution 250 are substantially equal. This kind of distribution is referred to as a “top hat” distribution as a result of the sharp sides and relatively even flat-top peaks, which give the data a kind of top hat shape. The distance D in each of the distributions 220, 250 of FIGS. 4B and 4C, respectively, refers to the outer diameter of the shaped beam responsible for the distributions 220, 250, while the distance d refers to the inner diameter of the same shaped beam.

[0076] As with previous designs, the monolithic optical element of FIG. 4A can also be used to shape lasers having asymmetric energy distributions. FIG. 4D depicts an arrangement including a monolithic optical element 200' and a laser source 230'. The monolithic optical element 200' is similar in structure to the monolithic optical element 200, and for brevity, like components will not be described again. The optical element 200' includes facets SI", S2", and S3", which are directly comparable to facets SI', S2', S3' of the optical element 200, but will slight modification, the facets SI", S2", S3" can be used to create an asymmetric irradiance distribution. By decentering S2" by about 0.2 mm from the optical axis, the optical element 200' can create an asymmetric energy distribution like the kind depicted in the distribution 220' of FIG. 4E. As shown in FIG. 4E, the lower region of the irradiance distribution 220' has a higher irradiance than the upper region, which would result in a partially annular or crescent-like MTZ. FIG. 4F depicts a distribution 250' cross section of the distribution 220' taken along the y-axis, and it can be seen that the left region within the distribution 250' reaches a higher irradiance value than the right region. This disparity between the left and right regions corresponds directly to the asymmetry in the distribution 220' taken along the y-axis as a result of the decentered S2". To further highlight this discrepancy, distribution 250' includes a indicator AE of a difference in maximum irradiances of the left and right regions.

[0077] In addition to the optical element designs featured having facets SI, S2, S3 and the like, other optical element designs having a different number of facets and can be used to collimate and shape beams (e.g., Gaussian beams) into beams of a desired irradiance distribution, including both symmetric and asymmetric distributions. Certain embodiments having two facets or surfaces of interest are depicted in FIGS. 5A-5G.

FIG. 5 A depicts an embodiment of an optical arrangement including an optical element 300 and a laser source 330. The specific design of the optical element 300 uses a method similar to the kind described within the following references, each of which are incorporated by reference: U.S. Patent No. 3,476,463 entitled “Coherent optical system yielding an output beam of desired intensity distribution at a desired equiphase surface,” “Comprehensive numerical design approach for refractive laser beam shaping to generate annular irradiance profile,” Optical Engineering, Meijie Li Youri Meuret Fabian Duerr Michael Vervaeke Hugo Thienpont, DOI: 10.1117/1. OE.53.8.085103, “Automatic optimization design of Gaussian beam shaping system by using Zemax software,” Optik, Yuhan Gao at al, 2011, doi: 10.1016/j.ijleo.2011.02.006, “Lossless Conversion of a Plane Laser Wave to a Plane Wave of Uniform Irradiance,” Frieden, Applied Optics, Vol4 Nol 1, Nov, 1965. These methods involve equating the energy at an optical path along rays between planes pl and p2, where pl is a vertical plane located at an entrance aperture of an optical element and p2 is a plane located at an arbitrary distance down-beam of the optical element. However, these references describe cases involving: 1) a diverging input beam; 2) a compact and monolithic optical element that does not require alignment; and 3) and optical elements that can generate symmetric or asymmetric beams having at least partially annular transverse energy profiles. Such cases are addressed herein by the optical element 300, for example.

[0078] The optical element 300 is an all refractive monolithic compact beam shaper that converts a diverging Gaussian beam into a collimated ring beam of uniform irradiance distribution. The optical element 300 includes a body 310 extending between a first end 312 and a second end 314. The first end 312 includes a first surface SI"' having a concave shape and defining an entrance aperture of the optical element 300. The second end 314 includes a second surface S2"' having a convex shape. The surfaces SI"' and S2"' are refractive and are coated in an anti-reflection material. In operation, a diverging Gaussian beam 332A emitted from the laser source 330 enters the optical element 300 via the first surface SI"'. As a result of the structure of the body 310 of the optical element 300, the beam 332Ais shaped and collimated into a beam 332B having an at least partially annular transverse energy profile without any internal reflection within the optical element 300.

[0079] Specifics of the design of the optical element 300 can be provided by the following equations Eq. 3 to Eq. 6, where: d is an inner diameter of the shaped beam 332B, D is an outer diameter of the shaped beam 332B, r is a radial distance mapped at pl, r' is a radial distance mapped at p2, wo is an initial beam diameter, w is a width of the beam at pl, k is a wavelength of the beam, zo is the Rayleigh range, z (also referred to as 1) is a length between the laser source 330 and the center of SI"', MFD is the mode field diameter, and 0 is the angle of divergence of the laser source 330.

[0084] Exemplary values describing the optical element 300 are included in the Table 2:

Table 2

[0085] Using Eq. 1 and Eq. 2 described above, the form of the optical element 300 can be expressed with the data of Tables 3 and 4:

Table 3

Table 4

[0086] In operation, the optical element 300 can convert a Gaussian beam having an irradiance distribution 340 like the kind depicted in FIG. 5B with width w and shape and collimate the beam into a collimated beam with an irradiance distribution 350 as depicted in FIG. 5C. The distribution 350 of FIG. 5C is a symmetric annular distribution similar to the distribution 220 of FIG. 4B, and at a cross-section taken along the x-axis, the distribution 350 has a top-hat irradiance distribution. FIG. 5D depicts the top-hat irradiance distribution 360 of the distribution 350, where D depicted in FIG. 5D corresponds to an outer diameter of the shaped and collimated beam 332B and d depicted in FIG. 5D corresponds to an inner diameter of the same shaped and collimated beam 332B.

[0087] FIG.5E depicts an optical element 300' and a laser source 330', which can be used to create a beam having an asymmetric irradiance distribution for the creation of partially annular or crescent-shaped MTZs. The optical element 300' and the laser source 330' are substantially identical to the optical element 300 and laser source 330'. For brevity, like characteristics will not be described again. The optical element 300' is rotated relative to the optical axis by an angle 0 equal to about 0.1 degrees. As a result, instead of producing an irradiance distribution like the distribution 350 depicted in FIG. 5C, the optical element 300' produces an asymmetric irradiance distribution like the distribution 350' depicted in FIG. 5F, where the lower region of the distribution 350' has a higher irradiance than an upper region of the distribution 350'. FIG. 5G depicts a graph 360' of irradiance levels of a vertical cross-section taken along the y-axis of the distribution 350', and the asymmetry AE between the left region and the right region is emphasized.

[0088] Optical elements can also be designed in order to convert a beam having a Gaussian irradiance distribution into a step irradiance distribution. FIGS. 6A-6G depict one embodiment of such an optical element. Namely, FIG. 6A depicts a compact monolithic optical element 400 that is able to covert a beam having a Gaussian irradiance distribution into a beam having a step irradiance distribution. The optical element 400 is a two-facet design, similar to the optical element 300, with the exception that each facet of the optical element 400 is substantially convex in form. Specifically, the optical element 400 includes body 410 having a first facet SI"" located at a first end 412 of the body 410 and a second facet S2"" located at a second end 414 of the body

410.

[0089] A specific exemplary form of the optical element 400 can be provided using Eq. 1 and Eq.

2, above, with data from Table 5 and Table 6.

Table 5

Tab e 6

[0090] In operation, the laser source 430, located a length 1 from the optical element 400, emits a diverging beam 432A having a Gaussian irradiance distribution at the first facet SI"" of the optical element 430. The optical element 400 shapes and collimates the diverging beam 432A into a beam 432B, emitted from the second facet S2"" having a transverse annular energy profile like the kind described herein. Ray mapping of the beam 432A through the optical element 400 can be calculated according to Eq. 7, where r, r', and w are described previously.

[0092] The shaped beam 432B will have a step irradiance distribution like the kind depicted in the distribution 450 of FIG. 6B. In this distribution 450, the outermost edge has the highest irradiance, while the innermost edge has the lowest. Further, the irradiance is directly proportional to the distance from the center of the annular distribution, which is characteristic of a step distribution. FIG. 6C depicts a graph 460 of a cross section of the distribution 450 taken along the x-axis, and it can be plainly seen that the change in irradiance when moving from the innermost edge to the outermost is substantially linear, peaking at the outer diameter D.

[0093] FIG. 6D depicts an optical element 400' and a laser source 430', which can be used to create a beam having an asymmetric irradiance distribution for the creation of partially annular or crescent-shaped MTZs. Both the optical element 400' and the laser source 430' are substantially identical to the optical element 400 and laser source 430. For brevity, like characteristics will not be described again. In this example, the optical element 400' is rotated relative to the optical axis by an angle 0 equal to about 0.1 degrees. The result of this rotation is that, instead of producing an irradiance distribution like the distribution 450 depicted in FIG. 6B, the optical element 400' produces an asymmetric irradiance distribution like the distribution 450' depicted in FIG. 6E. FIG. 6F depicts a graph 460' of a vertical cross-section taken along the y-axis of the distribution 450', and the asymmetry AE between the left region and the right region is emphasized.

[0094] As explained herein, the creation and manipulation of compact monolithic optical elements can be tailored to effect a specific result for the treatment of tissue using a beam that is shaped by the optical elements. The shaped beam interacts with tissue to produce the abovedescribed MTZs of varying shape. Examples of treated tissue and the varying MTZ shapes can be seen in FIGS. 7A-7D.

[0095] FIGS. 7A and 7B depict en face NBTC stained histology of human ex-vivo abdominoplasty skin respectfully treated with a symmetric ring beam and an asymmetric ring beam. As seen in FIG. 7A, the MTZs 512 resulting from a symmetric beam have an annular shape with islands of spared tissue 514 centrally located therein. As seen in FIG. 7B, the MTZs 522 resulting from an asymmetric beam having a partially annular or crescent-like shape, and the central tissue 524 remains connected to tissue surrounding the MTZs 522.

[0096] FIGS. 7C and 7D depict images of MENDS (Micro Epidermal Necrotic Debris) on skin taken three days after treatment with a symmetric ring beam and an asymmetric ring beam, respectively. Similar to FIGS. 7A and 7B, the MTZs 532 of FIG. 7C and the MTZs 542 of FIG. 7D depict the characteristic shapes of their respective beams, with the MTZs 532 sparing islands of tissue 534 in centers thereof and the MTZs 542 sparing central tissue 544 connected to tissue surrounding the MTZs 542. In FIGS. 7A-7D, not every MTZ or spared tissue is highlighted to provide a clearer depiction of the actual images.

[0097] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. “Approximately,” “substantially,” or “about” can include numbers that fall within a range of 1%, or in some embodiments within a range of 5% of a number, or in some embodiments within a range of 10% of a number in either direction (greater than or less than the number) unless otherwise stated or otherwise evident from the context (except where such number would impermissibly exceed 100% of a possible value). Accordingly, a value modified by a term or terms, such as “about,” “approximately,” or “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

[0098] The articles “a” and “an” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to include the plural referents. Claims or descriptions that include “or” between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context. The disclosure includes embodiments in which exactly one member of the group is present in, employed in, or otherwise relevant to a given product or process. The disclosure also includes embodiments in which more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process. Furthermore, it is to be understood that the disclosed embodiments provide all variations, combinations, and permutations in which one or more limitations, elements, clauses, descriptive terms, etc., from one or more of the listed claims is introduced into another claim dependent on the same base claim (or, as relevant, any other claim) unless otherwise indicated or unless it would be evident to one of ordinary skill in the art that a contradiction or inconsistency would arise. It is contemplated that all embodiments described herein are applicable to all different aspects of the disclosed embodiments where appropriate. It is also contemplated that any of the embodiments or aspects can be freely combined with one or more other such embodiments or aspects whenever appropriate. Where elements are presented as lists, e.g., in Markush group or similar format, it is to be understood that each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. It should be understood that, in general, where the disclosed embodiments, or aspects of the disclosed embodiments, is/are referred to as comprising particular elements, features, etc., certain embodiments of the disclosure or aspects of the disclosure consist, or consist essentially of, such elements, features, etc. For purposes of simplicity those embodiments have not in every case been specifically set forth in so many words herein. It should also be understood that any embodiment or aspect of the disclosure can be explicitly excluded from the claims, regardless of whether the specific exclusion is recited in the specification. For example, any one or more active agents, additives, ingredients, optional agents, types of organism, disorders, subjects, or combinations thereof, can be excluded.

[0099] Where ranges are given herein, embodiments of the disclosure include embodiments in which the endpoints are included, embodiments in which both endpoints are excluded, and embodiments in which one endpoint is included and the other is excluded. It should be assumed that both endpoints are included unless indicated otherwise. Furthermore, it is to be understood that unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or subrange within the stated ranges in different embodiments of the disclosure, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise. It is also understood that where a series of numerical values is stated herein, the disclosure includes embodiments that relate analogously to any intervening value or range defined by any two values in the series, and that the lowest value may be taken as a minimum and the greatest value may be taken as a maximum. Numerical values, as used herein, include values expressed as percentages.

[0100] In the descriptions above and in the claims, phrases such as “at least one of’ or “one or more of’ may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” In addition, use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

[0101] The subject matter described herein can be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and sub-combinations of the disclosed features and/or combinations and sub-combinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

Claims

1. A monolithic optical element, comprising: a body extending between a first side and a second side, the body being configured to: receive a diverging non-uniform fluence beam at the first side from a laser source, collimate and shape the received diverging non-uniform fluence beam between the first side and the second side, and emit a shaped and collimated beam from the second side, wherein the emitted shaped and collimated beam has an at least partially annular transverse energy profile.

2. The monolithic optical element of claim 1, wherein the emitted shaped and collimated beam has a radially symmetric energy profile.

3. The monolithic optical element of claim 2, wherein the emitted shaped and collimated beam is configured to produce MTZs in tissue having a substantially annular shape.

4. The monolithic optical element of claim 1, wherein the emitted shaped and collimated beam has a radially asymmetric energy profile.

5. The monolithic optical element of claim 4, wherein the emitted shaped and collimated beam is configured to produce MTZs in tissue having a substantially crescent shape.

6. The monolithic optical element of claim 1, wherein the body is further configured to emit a shaped and collimated beam having a top hat irradiance distribution.

7. The monolithic optical element of claim 1, wherein the body is further configured to emit a shaped and collimated beam having a step irradiance distribution.

8. The monolithic optical element of claim 1, wherein the body includes a first convex facet disposed at the first end and a second concave facet disposed at the second end, and wherein the first convex facet defines an entrance aperture of the body.

9. The monolithic optical element of claim 1, wherein the body includes a first concave facet disposed at the first end and a second concave facet deposed at the second end, and wherein the first concave facet defines an entrance aperture of the body.

10. The monolithic optical element of claim 1, wherein the body includes at least two facets covered in a high-reflectivity coating.

11. The monolithic optical element of claim 1, wherein the body includes at least two facets covered in an anti -reflective coating.

12. An optical arrangement, comprising: a laser source; and a compact monolithic optical element including a first side defining an entrance aperture and a second side having an at least partially convex facet, the first side being opposite the second side, wherein the compact monolithic optical element is configured to receive a diverging beam from the laser source via the entrance aperture and emit a collimated and shaped beam having an at least partially annular energy profile.

13. The optical arrangement of claim 12, wherein the laser source and the compact monolithic optical element are arranged in-line on an optical axis, and wherein the at least partially annular energy profile is fully annular.

14. The optical arrangement of claim 12, wherein the at least one of the laser source and the compact monolithic optical element are skew relative to an optical axis of the optical arrangement.

15. The optical arrangement of claim 14, wherein the skew is a rotation relative to the optical axis.

16. The optical arrangement of claim 14, wherein the skew is a translation relative to the optical axis.

17. The optical arrangement of claim 14, wherein the at least partially annular energy profile is radially asymmetric.

18. The optical arrangement of claim 12, wherein the compact monolithic optical element is configured to internally reflect the received diverging beam at least twice prior to emission.

19. The optical arrangement of claim 12, wherein the compact monolithic optical element is configured to collimate and shape the received diverging beam within internal reflection.