Hair removal method using optical pulses

The present invention relates to a method and an apparatus for removing hair by irradiation light. Related.

Extra hair (hypertrichosis) and / or unwanted hair is a common skin and cosmetic problem, such as hirsutism (ie, excess hair due to hormones such as androgens). It is caused by a hormonal, malignant, or endocrine disease.

Hair can be temporarily removed using a number of techniques, including depilatory waxes, depilatory creams, and, of course, shaving. Alternatively, an electrolyte can be used to permanently remove the hair. This method involves piercing the hair sac with an electric current carrying needle, which is often painful, inefficient and time consuming.

In order to remove hair, a method using light such as using a laser beam is also used. For example, U.S. Pat. No. 4,388,924 states that a laser is used to irradiate individual hair sac. In this method, as a result of heating the root portion of the hair, coagulation occurs in the local blood vessels and the hair sac is destroyed, so that the hair comes off. Related techniques, such as those described in US Pat. No. 5,226,907, first include destroying the hair sac by applying a light-absorbing substance to the area of interest, which is at least in the hair sac. It involves moving halfway to remove excess light-absorbing material, and then irradiating the area to heat the material, and thus the hair sac, and destroy the hair sac.<patcit num="1"><text>U.S. Pat. No. 4,388,924</text></patcit><patcit num="2"><text>U.S. Pat. No. 5,226,907</text></patcit>

<p> The above-mentioned prior art has a number of problems. First, the technique of irradiating individual hair sac is time consuming and is therefore generally impractical except when removing hair from a very narrow area or from an area with only a few hairs within it. This method also makes it easier for light energy to reach the dilations and roots or papillae that must be destroyed to prevent hair regrowth, especially if the hair sac is pierced with a needle-like element. Painful. If the radiation source is not inserted into this hair sac, it is difficult to obtain sufficient energy for the required part of the hair sac, and thus without significant damage to the surrounding tissue, thus causing pain and pain to the patient. Although it causes damage, its hair sac cannot be destroyed.</p><p> The latter patented technique is advantageous in that it allows the removal of a large number of hairs within a given area at the same time, but in the case of this technique, a light absorber, i.e. chromophore, is used to destroy the papillae. It is difficult to get the plaque deep enough into the sac. Moreover, as a result of this technique, a considerable amount of energy is applied and absorbed to the epidermis and other skin layers in the area to be treated, significantly reducing the energy reaching the papillae of the hair root or hair sac.</p><p> Hair sac is completely destroyed and therefore hair is removed permanently, or at least for a long period of time, without the risk of damaging the epidermis and other layers of skin within its area. Becomes difficult.</p><p> Thus, the area where the light energy is at the dilated part and at the root or at the root, while minimizing the damage to the epidermis within that area, thereby minimizing the patient's distress and the harmful side effects associated with the treatment. There is a need for improved techniques for removing hair that help reach the roots of the inner hair sac.</p>

<p> According to the above, the present invention provides a method and a device for simultaneously removing a plurality of hairs from a skin area, each of which is in a hair sac extending from the surface of the skin to the inside of the skin. This technique involves arranging the applicator in contact with the skin within the skin area and applying irradiation light of a selected wavelength and a selected amount of light to the skin area through the applicator for a predetermined time. And include. It is preferred that the applicator be pressed against the surface of the skin, thereby reducing the distance from the applicator to the papillae of the hair sac and facilitating the destruction of the hair sac. Furthermore, the present invention includes cooling the skin surface of the skin area to a selected depth during and / or prior to applying irradiation light to the skin area. This allows the papillae of the hair sac to be significantly heated to a selected depth without damaging the skin surface of the skin area.</p>

<p> In a preferred embodiment, the applicator is utilized to cool the skin surface within its skin area to a selected depth, the selected depth of which is the epidermal layer of the skin (ie, the skin surface). It is preferably at least equal to the depth of the skin layer closest to). Cooling by the applicator is performed, for example, by cooling at least the surface of the applicator in contact with the skin surface, and the cooling is preferably performed both before and during irradiation of the skin. In a preferred embodiment, cooling of the applicator is performed by passing a cooling fluid through the applicator. Further, it is preferable not to irradiate the skin surface until the skin area has been cooled to a substantially selected depth. In the most preferred embodiment, this cooling is performed both before and during irradiation, and the selected amount of light and the predetermined exposure time (ie, the time interval of irradiation) are selected as follows. .. That is, while the degree of heating of the skin within the skin area to the selected depth is at best minimal, the hair and hair sac deeper than the selected depth are sufficiently heated, significantly damaging the tissue surrounding the hair sac. Choose to damage at least the hair and sac without causing it. A suitable irradiation time interval is 2 to 100 ms. Further, it is preferable that the applicator is designed so as to converge the irradiation light applied to the skin region, thereby further promoting the irradiation of the epidermis of the hair sac. In a preferred embodiment, the applicator has a convex surface in contact with the skin surface, and a substantially uniform pressure is applied to the convex surface to deform the lower skin surface. In the alternative embodiment, the applicator is designed to form a folded portion of the skin within the skin area and to irradiate substantially both sides of the folded portion with irradiation light. For example, an applicator has a slot formed on the surface that contacts the skin surface, at least a portion of the skin area is drawn into the slot, and irradiation light is applied to the skin area from at least both sides of the slot. Can be done. Also, in the applicator and the above skin area It is also desirable to maintain a state in which the refractive index is substantially matched with the skin surface. Such a refractive index adaptation is such that a material layer with a suitable refractive index is provided between the applicator and the skin surface in the skin region, and / or at least the surface in contact with the skin region has a refractive index substantially compatible with the skin surface. It is achieved by manufacturing the applicator with the material having.</p><p> Hair in the skin area can be shaved prior to irradiation to facilitate hair removal. However, it is preferable to remove the hair in the skin area before irradiation. When the hair is removed, the hair sac is destroyed by filling the hair sac with a substance (that is, a chromophore) that preferentially absorbs light rays of a selected wavelength used for irradiation. Can be promoted. Furthermore, if it is desired to remove the hair only temporarily, it is preferable to shave the area in advance, and by imparting a chromophore to this area, it can be performed relatively painlessly over a period of several weeks. This chromophore penetrates into the hair sac to a few millimeters, or approximately the depth of the sebaceous glands. The low level irradiation of the skin area through the applicator then destroys the hair without destroying the hair sac.</p><p> According to the above, suitable applicators for use in removing hair include an inlet for applying irradiation light to the applicator, a surface in the skin area shaped to contact the skin, and the inlet. An optical path from to the surface (which is substantially transparent to light of a selected wavelength) and provided in the light path that converges the irradiation light as the light penetrates the skin and leaves the applicator. It can include elements and some means of cooling the surface to a temperature below the surface temperature. As described above, this surface is preferably made of a material having a refractive index that is substantially compatible with the refractive index of the skin surface within the skin region, but is not less than or equal to that refractive index. In a preferred embodiment, the element that converges the irradiation light is a lens, and the cooling means is a passage formed near the surface of the cooling water so that the cooling water can pass therethrough. In one embodiment, the surface of the applicator in contact with the skin has a convex shape, while in the alternative embodiment, a slot is formed on the surface and the optical path is the slot. It reaches at least both sides of the. Further, the applicator is provided with means for sucking at least a part of the skin area into the slot, and it is preferable that the suction means has an element for applying negative pressure.</p><p> The above and other objectives and features and advantages of the present invention will become apparent from the following more specific description of preferred embodiments of the invention illustrated in the accompanying drawings.</p>

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Referring to FIG. 1, a laser-based hair remover 10 as an example includes, for example, a light source 12 that can include one or more lasers that generate an irradiation field. The light source 12 is optically coupled to a series of beam-manipulating optics 14, which are coupled to an illuminator or applicator 18 via a fiber optic cable 16 (or other fiber optic device). can do. During the hair removal treatment, the light source is actuated by the voltage-current supply source 19 to supply a light beam to the irradiator or applicator 18 through the optical element 14 and the optical fiber 16. The area 20 of the patient 22 (eg, located at the position of the pedestal 25, chair or other suitable positioning element corresponding to the position of the area 20 in the patient's body) is supplied with a field of light. As a result, hair is removed from area 20. Once the desired area has been treated, the irradiator can be easily moved along patient 22 as indicated by arrow 27 and used to treat subsequent areas.

The spatial and temporal characteristics of the light field determine the efficiency of the hair removal process, and if desired, use a series of controls 24, 26, 28 provided on the various components of the hair removal device 10. Then, some of these characteristics can be adjusted. For example, a control device 24 provided in the power supply can be used to adjust parameters such as the voltage, current and switching speed of the laser output source to increase the intensity of light and the repetition rate of pulses in the field of irradiation. Can be controlled. Other properties of the field, such as wavelength and pulse duration, can be modified by the controller 26, which adjusts the components of the light source 12 (eg, the position of the grid, mirror or filter, shutter, or pulse generating means). is there. However, in the preferred embodiment, the wavelength is not adjusted. Similarly, the controller 28 can be used to adjust the modulation optics 14 to control light characteristics such as mode quality, beam diameter, and coupling of fiber optics 16 to the field of illumination. .. All controls are manually adjustable. The device can be actuated by hand (ie, actuating the laser) or, alternative, using the foot pedal 30 connected to the device 10.

In an alternative embodiment, the light source, coupled optics, and irradiator can be housed in a single portable device. In this case, it is preferable that the light source is directly coupled to the irradiation device and is fed from a small external power source as an array of diode lasers. Due to the compact nature of this optical device, it becomes a more controllable and operable device, and further, an optical fiber feeding device is not required.

In order to efficiently destroy the irradiated hair sac without damaging the surrounding tissue, the irradiation field supplied by the device 10 and the irradiation device 18 is the amount of heat generated by the light and applied to the hair sac. It is designed to maximize the degree of damage to the surrounding skin while reducing the degree of damage to the surrounding skin. For example, sufficient light energy may be supplied to several "target" areas on the hair sac so that the irradiation light delivered to these areas results in complete and local destruction of the hair sac. It is preferable to do so.

Prior to treatment, the area to be treated can be shaved to facilitate irradiation of the hair sac. Alternatively, as described below, the hair in the area is depilated to impart a chromophore to the area 20 so that the chromophore enters the empty hair sac. The excess chromophore can then be removed from the skin surface prior to irradiation. Prior to treatment, an anesthetic can be sprayed or applied to a portion of the skin surface, and after treatment, the patient can be treated with a topical antibiotic ointment.

<u style="single">Mechanical structure</u> Next, referring to FIGS. 2A and 2B, the applicator or irradiation device 18 of the hair removing device makes it possible to supply an irradiation field 38 to the hair sac 40 within the region 20. As illustrated in FIG. 2A, this irradiation field 38 is supplied to the irradiation device 18 using a fiber optic cable 16 (or other fiber optic device) that houses a bundle of one or more fibers or fiber optics. can do. In this case, after exiting the waveguide, the irradiation field 38 is typically spatially dispersed, preferably collected and roughly collimated using a plano-convex lens 42. Alternatively, as illustrated in FIG. 2B, for example, one or more reflection mirrors 44 may be used to supply the irradiation field to the irradiation apparatus. This makes it possible to substantially collimate the irradiation field 38 before colliding with the lens 42. Corresponding to the focal length of the lens 42 and the quality of the mode of the irradiation field, the field is preferably focused using, for example, the plano-convex lens illustrated in the drawings. After passing through this optical element, the beam collides with a lens or contact device 46 located in contact with the skin region 20. The optical and mechanical properties of the contact device 46 have been selected so that light rays can be efficiently combined with the skin area (which becomes the supplied irradiation field 38), and the thermal properties of the contact device are its skin. It is selected so that heat can be efficiently combined from the region. Once supplied, the field of irradiation is used to irradiate, heat, and then destroy the hair sac 40. In addition, the contact device 46 is used to bind and heat light to the superficial skin layer (ie, epidermis) of the irradiated area. This causes the hair sac to be permanently destroyed by irradiating and selectively heating a light-absorbing pigment (ie, melanin) retained in the deep part of the hair sac, while at the same time being harmful. Transfers some light and heat energy to the outside of the skin layer above it. In this way, a large number of hair sac can be destroyed and hair can be permanently removed from the skin area without significantly distressing or damaging the patient. The removed hair sac is finally removed by the body.

The lens 42 and contact device 46 are located within a housing 48 having both inlets 50 and outlets 52 for fluids such as cooling water and pure gas (ie, nitrogen that prevents solidification on the lens) to enter and exit. Is preferable. For example, a fluid can be used to cool the contact device 46, while the contact device cools the surface of the skin. Alternatively, the housing 48 can include a cooling device that is electronically controlled so that the temperature of the contact device 46 can be precisely controlled. When cooling means are used, the temperature of the surface layer or epidermis of the skin drops to 4-15 ° C. Further, in this case, it is preferable to leave it for a short time (for example, about 1 second) before irradiation so that the epidermis is sufficiently cooled. As shown by the dashed line in FIG. 2B, the light supply means can be connected to the housing 48 using the outer casing 39 or the optical coupling housing 37 as shown in FIG. 2A.

Next, referring to FIG. 3A, it is preferable to form the contact device 46 in the shape of a lens so that the irradiation field can be converged near the base of the hair sac 40. To converge the light, the contact device is optically transparent to the irradiation wavelength, preferably biconvex with an f number of f / 1.0 or less and a focal length in the range of about 0.5 to 2 cm. It is preferably in the shape of a mold or plano-convex lens. By controlling the surface shape of the contact device, the converged light field 38'can simultaneously irradiate various target parts of the hair sac and efficiently destroy them. Typically, each of the axes of the irradiated hair sac is about 75 μm in diameter, and the entire hair sac is about 200 μm in diameter. After passing through the contact device 46, the light field 38'can be converged through the epidermis 56 of the skin layer (eg 0.1 mm thick) and focused into the dermis 58 near the papilla 54 of the hair sac 40. preferable. The thickness of the dermis varies significantly throughout the body, so if the nipple is on the surface (eg, in the eyelids and scrotum) but in most areas of interest (eg, face, armpits and feet), the nipple is on the epidermal surface. It is at a depth of about 4 to 7 mm below. Below the nipple, a few tenths of a millimeter, there is a bundle of nerve vessels 60, which is a matrix of hairs (located within the papilla and forms the axis 55 of the hair). Corresponds to the metabolism and other needs of rapidly growing keratinized cell areas). The matrix, nipple, and corresponding vascular bundle, as well as the dilated portion near the center of the hair sac, are the target portion of the hair sac to be irradiated and destroyed. While irradiating these areas, the light field is pulsed, the duration of the irradiation pulse is kept short enough, and according to the principle of selective photothermal decomposition, a small area of the dermis surrounding each of the hair sac (typically). Only within about 0.2 mm) should be locally damaged. The degree of this damage is preferably 1/2 or less of the distance between adjacent hair sac (typically 1 to 4 mm). If it is significantly higher than this value, there is a risk of 3 burns as a result of light damage.

In addition to providing the ability to converge the light, the contact device 46 with the convex surface 62 allows the skin to be effectively compressed during contact. The compression of the dermis 58 near the surface 62 of the contact device reduces the distance between this region and the papilla. This distance can be reduced to a few millimeters, depending on the force applied. The light field 38'is scattered as it propagates through the dermis and is correspondingly attenuated, resulting in more light directed into the deeper part of the hair sac as a result of skin compression and the papillae. Can be heated with light more efficiently. In addition, compressing the dermis with a contact device using a pressure higher than the patient's blood pressure pushes light-absorbing blood out of the irradiated area (during treatment, the skin in the pressurized area becomes white. Recognized by). As a result, the absorption effect of the light field is reduced, and light can be supplied to the target region of the hair sac more efficiently. The pressure applied using a contact device with a convex surface will displace the blood relatively uniformly from the skin area. For this reason, the contact device having this shape is preferably a flat device that produces a region having a central portion that is not completely blood-free.

In another embodiment, the contact device can be mounted in the housing in a spring loaded form so that the device is pressed against the surface of the skin with adjustable pressure. Further, in this embodiment, a spring mechanism can be attached to the sensor and reading device to accurately monitor and / or control the exact pressure exerted on the surface of the skin. The contact device 46 allows the irradiation light to be bound into and out of the epidermis when pressed against the skin. Next, referring to FIG. 3B, the index of refraction (n) of the contact device 46._CD) Is the index of refraction (n) of the epidermis 56_EP) (Approximately 1.55). Light traveling from one refraction medium (ie, the contact device) to another medium (skin) is reflected by the interface 57, which separates the two regions, by an amount equal to the square of the difference in refractive index. If the refractive index is substantially matched, the irradiation field can be efficiently bound in the skin. In this way, a contact device made of a material having a refractive index of about 1.5 or slightly greater allows the field of incident irradiation to be reflected to a minimum at the epidermis / contact device interface 57 (drawing). Illustrated by arrow 64).

Similarly, as indicated by arrow 66 in the drawing, the light field within the dermis is scattered posteriorly towards the epidermis by diffuse reflection. These backscattering fields contribute to the unnecessary heating of the epidermis, but can be easily coupled to the outside of the skin using a contact device 46 with a suitable index of refraction. This minimizes light-induced damage to the epidermis 56, while allowing effective irradiation of the target area of the hair sac within the dermis. In a preferred embodiment, the contact device is sapphire (n) in order for the refractive index to be substantially compatible._CD= 1.7), fused silica (n)_CD= 1.5), or similarly preferably made of a high density material such as optically clear glass or plastic. In order to provide a convergence field that enters the skin and to have the convex shape of the contact device as shown, it is advantageous to use sapphire that promotes the desired convergence field due to the slightly higher index of refraction. is there.

Next, referring to FIG. 3C, in order to transfer heat from the epidermis, the contact device 46 has a high thermal conductivity (k) similar to that of the skin._CD) Is more preferable. This allows heat to be efficiently transferred from the epidermis 56 into the contact device 46 across the contact device / skin interface 57 (as indicated by arrow 68 in the drawing). In addition, high thermal conductivity must be achieved to minimize the local heating effect that occurs at the interface 57, thereby reducing thermal damage or injury to the irradiated epidermis. This is especially important when the contact device is cooling, as described below. Ideally, due to the thermal properties of the contact device and the amount of time the contact device is in contact with the skin before the start of irradiation, the degree of heating near the epidermis is minimized, but near the papillae of the hair sac (as area 70 in the drawing). There is almost no effect on the heat applied to (shown). For materials with high thermal conductivity, sapphire (at 30 ° C, along the C axis, K_CD= 0.083 calories · sec^-1·cm^-2 ° C cm^-1), Fused silica (at 30 ° C, along the C axis, K_CD= 0.026 calories · sec^-1·cm^-2 ° C cm^-1), And other high density glass and plastics.

Further, in order to improve both the light characteristics (that is, the transmission of backward scattered light) and the light characteristics (that is, the heat conduction characteristics) at the contact device / skin interface 57, the refractive index of the contact device 46 and the skin It is desirable to apply topical liquids and ointments such as lotions, water or oil with a refractive index similar to that of the skin. For example, by applying an oil having a refractive index in the range of the index of refraction of the epidermis (n = 1.55) and sapphire (n = 1.7), the light reflection effect at the interface is minimized, thereby causing the skin from the contact device Light can be transmitted more efficiently into the region, and backscattered light from the skin region can be transmitted more efficiently. In addition, the liquid conducts heat from the skin into the sapphire to efficiently transfer heat, which can reduce the degree of damage or injury to the epidermis.

<u style="single">Light characteristics</u> The distribution of temporal and spatial intensity of the light field in the skin ultimately determines the amount of heat applied within the target area of the hair sac. Therefore, these properties can be selected and / or adjusted to optimize the hair removal process. In particular, the properties that affect the hair removal process are pulse energy, pulse duration, repetition rate (ie, time between subsequent pulses), wavelength, energy, exposed area dimensions, and beam convergence as it enters the skin. Includes degree and form of pulse mode of light (ie, spatial extent and uniformity). These properties can be selected to correspond to the hair to be irradiated and the pigment present in the skin. Each of the parameters is preferably adjusted so that the temperature at each target site immediately after irradiation rises to a range of about 80 to 120 ° C. Heating the hair sac to this temperature causes permanent damage that can be subsequently removed.

Then, referring to FIG. 4, the wavelength of the irradiation field resonates with the natural pigment (ie, melanin) present within the target site (ie, hair axis, dilation, matrix and papilla). Select. The absorption spectra of melanin, water, hemoglobin and oxidized hemoglobin illustrated in the drawings show the ability of these compounds to absorb light of different wavelengths. The low degree of absorption indicates that light at a specific wavelength penetrates deeper into the absorption medium. In general, in order to selectively heat the target region, the wavelength of the irradiation field is basically selected to match the absorption spectrum of melanin, which absorbs light of about 200 to 1200 nm. Conversely, the wavelength should be incompatible with the absorption spectrum of compounds contained within the skin, such as water and hemoglobin. Light with wavelengths in the range of 680 to 1200 nm (this range is indicated by arrow 70 in the drawing) is effectively absorbed by melanin while being relatively transmitted by hemoglobin and water, so that such light is It can be used to selectively heat pigmented hair surrounded by white or slightly brown skin. In particular, the light is preferably in the range of 680 to 900 nm or 1000 to 1200 nm, which is strongly absorbed by melanin but not by bands and oxidized hemoglobin present in water near 950 nm. Because. For patients with low melanin content in their hair sac (eg, reddish brown or light brown hair), shorter wavelengths within this region are preferred because of the higher absorption of melanin. In addition, other light attenuation effects other than absorption, such as scattering of irradiation light, are also wavelength dependent and should be considered when choosing the wavelength of the light field. For example, in human skin, a part of the degree of light penetration is the transmission scattering rate (μ)._s), This value is smaller because it scatters in the dermis at longer wavelengths. When irradiating at 1000 nm, this μ_sIs about 10 cm^-1Is. Therefore, at this wavelength, the light transmitted into the skin from a medium with a substantially suitable refractive index reaches its maximum intensity at a depth of about 1 mm on the surface of the skin.

Light sources that generate visible or near-infrared light within the preferred range of 680 to 1200 nm are diodes (λ = 800-1000 nm), neodymium: YAG and neodymium: YLF (λ = 1064 to 1053 nm), titanium: sapphire and Includes infrared dyes (λ = 700-1000 nm), ruby (λ = 694 nm) and Alexander stone (λ = 700-850 nm) lasers, ruby, neodymium: YAG. The use of diode lasers is preferred because diode lasers (particularly specific arrays of diode lasers) are commercially available and are available in sufficient variety and can be manufactured on a small scale. While this type of light source can be incorporated into a compact hair remover, the hair remover is easily operable by the operator during the process of removing hair.

The duration of the light pulse can be controlled so that the degree of heating of the hair sac can be varied. Next, referring to FIG. 5A, the light pulse shown in waveforms 74, 74'preferably has a duration of 76, 76', which allows the hair sac to be heated in a short period of time. This pulse width is controlled so that it can change the thermal conductivity between pulses of light and thus the extent to which it damages the hair sac and the dermis around it. Hair is regenerated with little damage, but severe damage can leave scars on the irradiated area. The pulse durations 76, 76'preferably in the range of about 2 ms to about 100 ms.

The exact duration of the pulse is determined by the diffusion of heat in the skin roughly according to the thermal diffusion equation for diffusion time t, diffusion distance d, and thermal conductivity k. This is the "The thermal response laser-irradiated tissue" published by Welch AJ in IEEE J.Quant.Electron.QE-21 (12), 1471-1481 (1984). ) , And t = d²/ 4k (k is about 1.3 × 10 for human dermis^-3cm²/ Second). The time required to recover heat from the epidermis during a laser pulse is about 2 ms, and for a typical 200 μm hair sac, the heat relaxation time is about 40 ms. When exposed for longer than a few hundred milliseconds, an excessive amount of heat diffusion occurs during the exposure period. It results in inefficient destruction of the target area of the hair sac and excessive damage to the dermis, or both. Furthermore, since most of the melanin in the epidermis (about 2/3) is in the lower part of the epidermis, the heating of the epidermis is mainly done in the deeper part, and this heat is required to be removed by the contact device 46. May be required to reach its surface. Therefore, since this time is at least 2 ms, this is the minimum pulse time suggested and may be a longer time, preferably at least 5 ms, to minimize epidermal damage. It is suggested. Further, depending on the laser utilized, each of the pulses can be in the form of a single continuous pulse as shown in FIG. 5A, or in the form of a narrowly spaced pulse train with a shorter duration, which is narrower The space between pulses should be much shorter than 5ms.

To obtain a given force, the field strength of the light field is inversely proportional to the duration of the pulse. Thus, when the duration of this pulse is less than about 10 μs, the light intensity is further increased, resulting in an undesired mode of damage to the surrounding skin area. In addition, the short pulse results in a local thermal "explosion" within the hair sac, which causes mechanical damage to the skin. In a particularly preferred embodiment, the pulse has a duration of about 2-100 ms, or a pulse width. During this time, thermal diffusion occurs over a distance of about 0.05-0.3 mm. As a result of this distance-limited damage, the sac of the irradiated hair is primarily destroyed with little or no damage to the surrounding skin.

Pulses of light with a properly set and adjustable duration can be generated using known techniques. For example, intracavitary modulation of the light field using an electronic or acoustic-optical Q-switched device makes it possible to generate pulses that typically have a Gaussian-shaped time profile. However, the pulses formed using these methods are typically very short and their duration is in the range of microseconds or less. Ruby, Alexander stone, titanium: sapphire, or neodymium: YAG lasers are typically high-energy pulses within the duration range of 0.1-10 ms pulses, so they are usually generated by the excitation of these flash lamps. It is preferably a mode pulse. Alternatively, for example, a mechanical shutter or an electro-optical gate can be used to externally modulate the continuous (ie, time-corresponding) light field emitted by the laser. Modulation using an external method makes it possible to easily change the pulse width from hundreds of microseconds to hundreds of milliseconds. The pulses generated using external modulation have a "square wave" temporal profile (shown in Figure 5A), which provides a more uniform light field for the region of interest. To enable. However, this external modulation method is not used in current embodiments.

When using a contact device to deliver a pulse of light, it is preferable that there is a time lag between the time point at which the contact device contacts the surface of the skin and the time the pulse arrives. This allows the entire epidermal layer 56 to be significantly cooled prior to irradiation, thereby increasing its damage threshold. In this way, the pain and damage of the epidermis are reduced, and by continuing to cool the contact device 46 during irradiation, the heat can be further minimized and the heat can be continuously removed from the epidermis. However, low levels of heating of the hair sac, especially its dilated parts and areas that are likely to damage the nipple, are unaffected by the cooling performed before and / or during irradiation. In addition, the duration between light pulses (indicated by arrow 78 in FIG. 5A) can be adjusted to control the total amount of heat applied to the irradiated area and its average velocity. If repeated irradiation is required to destroy the hair sac, this time is constant and preferably in the range of seconds to hundreds of milliseconds. Alternatively, in the case of "single shot" irradiation, this time interval is selectively controlled by the operator. In this case, a single laser shot is delivered to the area of interest and then the operator inspects the area for damage. If additional irradiation is required, additional laser shots can be made on that area. Otherwise, the irradiator is moved and used for treatment of another area.

The size of the space of the light field is selected so that a single laser shot can irradiate multiple hair sac. Further, as the beam radius R increases, the degree of attenuation along the beam axis in the skin decreases due to scattering, so a larger spot size is preferable. Thus, the large area beam makes it possible to more efficiently deliver the light beam to a deep target location. Next, referring to FIG. 5B, the width 80 of the spatial profile 82 of the irradiation beam on the surface of the skin is preferably about the depth of the target to be irradiated, and may be much deeper than that depth. preferable. Most preferably, the diameter of the beam is at least 8 mm. The area of the light field is about 0.5 to 2 cm²Is preferably 0.75 to 1 cm²It is most preferably in the range of. Since this beam is preferably convergent, this spatial profile shall reduce as a function the depth defined by the scattering of light within the dermis before reaching the constriction. As illustrated in FIG. 5B, the intensity across the diameter of the beam is preferably substantially constant so as to provide a substantially uniform field of light.

Next, referring to FIG. 6, after irradiation, the distribution of light intensity (ie, y-axis in the drawing), which is a function of the skin depth (ie, x-axis), uses a Monte Carlo computer simulation. It is calculated. This distribution state is a function of the spatial profile of the beam and the optical properties of the medium in contact with the skin. The plotted data is based on computer simulation and is therefore only an approximation, but the x-axis unit is estimated to be about 500 μm per scale. The first curve 90 exhibits skin depth-dependent properties with respect to the field of light generated from small collimated spots of 800 nm light in the air. In this case, most of this light intensity is distributed near the surface of the light (indicated by the "0" point along the x-axis), and the intensity drops sharply at deeper points. The larger collimated spots (curve 92) originating from the air are more evenly distributed in intensity depending on the depth of the skin, but most of this light is still concentrated near the surface of the skin. Supplying a large collimated light spot from a material with a refractive index of 1.5 (Curve 94) results in a relatively uniform light intensity, such as in the first 1 mm of skin. At deeper depths, this strength begins to decline with a relatively slow time constant. Finally, in a preferred embodiment, a large spatially converging light field from a material with a refractive index of n = 1.5 increases to a maximum after the intensity on the skin surface has advanced approximately 1 mm into the skin. .. This strength then decays as a function of skin depth with a slower time constant than that shown by curve 94. Thus, this type of field can be used to effectively heat the target area of the hair sac to reduce the degree of heating of the skin surface, thereby reducing heat damage to the skin.

If the irradiating laser produces a beam with a diameter smaller than the preferred value, it is necessary to extend the beam before it is fed to the irradiator. This can be done with conventional telescopic optics, for example, a two-lens system in which the emitted beam is first expanded and then the emitted light is collimated. .. Alternatively, as illustrated in FIG. 2A, the field of irradiation can also be coupled within the optical fiber and then supplied to the irradiation device. In this case, due to the nature of the waveguide of the fiber, the generated field is naturally dispersed and then focused by the collimating lens. By displacing the lens from the fiber tip, the profile of the irradiation beam can be increased to a desired degree. The force of action of the light field should be different depending on the degree of pigmentation of the patient, about 10-200 J / cm for each pulse.²It is preferably in the range of. Patients with darker hair may have less force than patients with lighter hair. The acting force of the pulse in the irradiation field for the pulse with a duration of about 1 ms is 30 to 50 J / cm.²It is most preferably in the range of. As described herein, in all cases this force is adjusted so that the target region can be heated to a desired temperature of about 80-120 ° C. However, the longer the duration of the pulse, the greater the degree of this force of action, and the inefficient heating of the hair sac due to heat conduction between long pulses can be compensated. If the wavelength of the light field to irradiate is not in the preferred spectral range (ie, 680-900 nm or 1000-1200 nm), the light acting force is increased or decreased in order to heat the hair sac to the desired temperature. It is necessary to let it. In addition, if the laser output is less than or equal to the desired light force, the individual pulses must be amplified before irradiating the skin. An optical amplifier such as an external optical cavity can be used for this purpose.

Table 1 below shows the preferred parameters of the light field used to remove hair. The value of each parameter depends on the amount of hair in the area of interest, the degree of hair pigmentation, and the pigmentation of the skin surrounding the patient.

<tables num="1"><img file="JP4159595B2_D0001.tif" /></tables>

The present invention will be further described below with respect to the following examples.<u style="single">Example</u> In order to demonstrate the efficiency of the hair remover according to the present invention, the pulse duration is 270 μs and the light acting force is 40 J / cm.², 71J / cm², 160J / cm²In vitro light from the normal mode of a ruby laser at λ = 694 nm was used to irradiate the skin of the dog's black hair.

Due to the spatial breadth of this beam (8 mm in diameter on the surface of the skin), a single laser shot could irradiate about 100 hairs. After this irradiation, each of the skin areas was histologically examined. Examination revealed that when the force of action was maximum, damage to the dermis occurred, which coincided with the scars on the skin, and the method of heat damage using the light of the maximum force of action was to the hair. It turns out that should not be selected. On the other hand, when the acting force is smaller, especially 40 J / cm²At this time, local damage to the hair sac was observed, and no significant damage was caused to the adjacent skin area or dermis between the hair sac.

In a separate examination, to show that the temperature rise inside the irradiated hair depends on the degree of pigment, using the hair removal methods described herein, new hair between different colors and The skin specimen was irradiated. The light source for all experiments was the ruby laser described above. The emitted light is first coupled into a closed beam manipulator that houses several mirrors coated to have a large reflectivity of 694 nm, and then similar to that illustrated in FIG. 2B. It was supplied to the irradiation device of. The irradiator includes a 5 cm plano-convex lens located at the base end of a water-cooled plexiglass housing. A sapphire contact device in the shape of a 1 cm focal length lens was placed at the end of the contact device so that the convex side was in contact with the skin and could be compressed during irradiation, as described above. Human skin was irradiated with a beam 8 mm in diameter by pressing a cooled (4 ° C) contact device against the patient's skin area, followed by a single laser shot. Each shot typically irradiated about 10 hairs at the same time.

The skin and hair of 6 adult patients with hair colors ranging from red to black were irradiated and the results were observed. In each patient, each 10 cm²Eight treatment sites with an area of were irradiated. To monitor the destruction of the nipple, areas 1 to 4 were depilated before irradiation with laser light, while areas 5 to 8 were shaved before irradiation. Next, the light acting force is 28 J / cm.², 42J / cm²Or 57J / cm²Each part was irradiated as one of. Patients after treatment were examined and observed every 1 and 3 months (1 year in some cases) after irradiation. As can be seen from the photographs of the irradiated areas (ie, areas A to C) shown in FIG. 7, in all cases the hair after 3 months compared to the shaved but untreated area (area D). Re-growth is minimal or not observed at all, clearly indicating that the hair sac has been permanently damaged. In the drawings, points A to C were treated by reducing the energy from the laser. 27J / cm²It is clear that relatively few hairs were removed in region C treated with the force of. The control region, region D, was shaved on the same day that regions A to C were treated. Furthermore, histological specimens obtained from the treated area showed that only the hair sac was damaged and the dermis around it was largely preserved. Statistically, there was virtually no hair in all subjects treated with the laser compared to controls that were not shaved and irradiated. One year later, the hair was almost permanently gone, leaving no scars.

A separate experiment was performed using a pulsed photothermal radiometry (PPTR) device that allowed the measurement of time-dependent temperature characteristics of hair and skin specimens. In these tests, the low-acting ruby laser described above was used to provide an optical pulse with energy that heats the hair sac but does not destroy it. The output from this laser was converged on human hair and skin specimens to provide a uniform excitation field. Specimen time-dependent temperature characteristics for specimens using New England Research, Inc. blackbody radiation detectors with built-in amplified, liquid nitrogen-cooled HgCdTe detectors And the irradiation pulse was monitored using a laser energy meter from Gentec, Inc. The output from both detectors was then amplified by a compensated 0-10Mhz DC-coupled preamplifier and then transmitted to a digital oscilloscope for data recording and storage.

Eight patients with various types of skin and hair colors ranging from red / blonde to black were tested. In general, PPTR results show that after irradiation at 694 nm, black hair warms more rapidly than light brown hair, and both specimens are more than red / blonde hair. It was found to show a rapid temperature rise. Furthermore, after irradiation, type II skin had a slower rate of temperature rise than type III or type IV skin.

Next, referring to FIGS. 8A-8C, in a special experimental example performed on patients with black hair and white skin, wet hair and dried from the time-dependent curves measured using a PPTR device. Both black hairs showed a temperature rise of about 7 ° C and about 72 ° C from a reference temperature of 23 ° C 400 ms after irradiation (Fig. 8A and Fig. 8B), while the surrounding skin (Fig. 8C). It can be seen that the temperature rise is 1 ° C or less. This difference in the characteristics of temperature rise in wet hair and its time-dependent destruction is believed to be due to thermal effects (eg, wet hair has a higher heat capacity).

Then, referring to FIG. 9, in all cases the normalized temperature rise (ie, the ratio of temperature rise to laser pulse energy) in the sac of wet and dry hair is higher than that measured in the skin. Significantly large, indicating that the hair sac was selectively heated using the method of the invention. Table 2 below lists the hair and skin types for each patient in this study. The patient numbers listed in this table correspond to the patient numbers in FIG.

<tables num="2"><img file="JP4159595B2_D0002.tif" /></tables>

<u style="single">Other embodiments</u> FIG. 10A illustrates an alternative embodiment of the invention in which the area 20 has been depilated rather than simply shaved prior to treatment according to the invention. A fluid solution or suspension 100 containing a chromophore, which contains a fluid that enters the empty hair sac and fills the hair sac, can then be applied to the skin area 20. The "capillary action" of the fluid / chromophore into the hair sac is desirable and can be achieved by reducing the surface tension between the fluid and the skin, for example by using a surfactant or solvent. Capillary action can be increased. Excess fluid / chromophore can then be removed from the skin surface by washing, wiping, or scraping. During irradiation, the chromophore 100 in the hair sac absorbs light and is heated with the heating of the melanin in the hair sac itself, significantly heating the hair sac and expanding as needed to prevent hair regrowth. The part and the part including the nipple can be destroyed. Thus, the chromophore must absorb light of one or more wavelengths used for irradiation. Suitable chromophores can include suspensions of carbon particles or pigments such as methylene blue or indocyanine green. Melanin itself in the form of liposomes may be used. Because this chromophore only enters the hair sac, this technique maximizes damage to the hair sac while minimizing damage to the surrounding tissues, for this reason blonde, red, light brown or others. It is a suitable method for carrying out the present invention for those with light-colored hair. Except for the differences described above, this embodiment of the invention is the same as that described for the previous embodiment, including cooling the contact device 46, deforming the skin within region 20, and suitable irradiation light. The only exception to this is that low frequencies can be used when using chromophores.

FIG. 10B illustrates another alternative embodiment of the invention in which the contact device or applicator 46 ́ has been modified to allow simultaneous irradiation of both sides of the folded portion of the skin. This further increases the amount of light delivered to the deep part of the hair sac. In FIG. 10B, the contact device has, for example, a formed opening or slot 110 on the surface of the applicator, for example, the skin by applying negative pressure or suction to the line 112 reaching the top of the slot 110. Region 20 can be aspirated into this applicator. The skin in slot 110 is made to be a fold portion 113. The irradiation light is applied through the optical fiber bundle 114, and the optical fiber bundle divides the irradiation light and applies the light to the lenses 116 on both sides of the slot 110. Cooling water can flow over the surface of the lens 116 through the wire 118. Alternatively, on both sides of the skin fold formed by grabbing the skin area in between or by other suitable means, for example, two applications similar to those shown in FIGS. 2A and 2B. Can be placed.

As described with respect to the embodiments described above, the advantage of folding the skin is that irradiation light is applied from both sides to a relatively thin portion of the skin. Thus, the papillae of a given hair sac can receive light not only from the lens 116 on the side of the slot 110 where the hair sac is located, but also from the lenses 116 on both sides of the slot. .. In this way, the energy applied to each papilla of the hair sac is increased without increasing the surface energy, which facilitates hair removal with less pain and damage. By forming the slot 110 relatively narrowly, pressure is applied to the skin on both sides of the slot and the skin is compressed between the slot walls. In this way, the advantages associated with compressing the surface, including removing blood and reducing the distance from the skin surface to the papilla, are also realized by this embodiment of the invention. In addition, pressure is applied to the skin by grasping it so as to form a folded portion.

It is also possible to utilize the teachings of the present invention for short-term hair removal, the device acting as a razor that lasts for a shaving effect, for example, perhaps for a week or two. This is done by applying fluid / chromophore to the area to be "shaving". The area is preferably shaved using conventional techniques other than hair removal procedures.

In this case, the chromophore can only penetrate a few millimeters into the hair sac, for example up to the level of the sebaceous glands. The excess chromophore is then removed and the contact device of the invention is used with relatively low levels of light to heat the chromophore and develop color without significantly damaging either the skin or the hair sac. The hair surrounded by the troupe can be destroyed. Further, for a preferred embodiment, cooling water has been shown as for cooling the contact device 46, but this is not limited to the present invention and other cooling techniques may be utilized. .. For example, a cold gas or liquid may be passed over the contact device for cooling purposes, or the contact device may be sufficiently cooled prior to use to continue the cooling function without passing a cooling medium over it. You may do so. It is also possible to use other cooling techniques known in the art.

Other embodiments are described in the claims below. For example, the contact device can cool the epidermis without cooling or using an applicator (eg, at cryogenic temperatures). When the applicator is not used, the irradiation light is directly applied to the target area after passing through an appropriate optical element.

Thus, although the present invention has been specifically illustrated and described above with respect to preferred embodiments, the above embodiments and details, as well as other modifications, can be made by those skilled in the art without departing from the spirit and scope of the invention. It can be done.

<figref num="1">It is a perspective view of the hair removal apparatus using a laser by this invention.</figref><figref num="2A">FIG. 5 is a cross-sectional view of an irradiator or applicator suitable for use with the hair remover of the present invention, which receives light from an optical fiber or optical fiber bundle and a mirror assembly, respectively.</figref><figref num="2B">FIG. 5 is a cross-sectional view of an irradiator or applicator suitable for use with the hair remover of the present invention, which receives light from an optical fiber or optical fiber bundle and a mirror assembly, respectively.</figref><figref num="3A">It is an exploded cross-sectional view of the contact device of the irradiation device which came into direct contact with the skin region containing hair.</figref><figref num="3B">It is a notch sectional view which shows the field of the backscattered light in the interface area of a contact device / epidermis.</figref><figref num="3C">It is a notch sectional view which shows the state of heat transmission in the boundary surface region.</figref><figref num="4">It is a plot figure which shows the light absorption spectrum of melanin, hemoglobin, oxygenated hemoglobin and water.</figref><figref num="5A">FIG. 5 is a diagram of the time and space profiles employed in the process of removing hair as well as suitable light fields.</figref><figref num="5B">FIG. 5 is a diagram of the time and space profiles employed in the process of removing hair as well as suitable light fields.</figref><figref num="6">It is a plot figure of the light intensity by computer calculation which makes the depth of the skin with respect to the different light fields a function.</figref><figref num="7">It is a photograph which shows the skin area of the patient 3 months after the treatment according to the hair removal method of this invention.</figref><figref num="8A">FIG. 3 is an oscilloscope diagram showing the time-corresponding temperature of dry black hair, wet black hair, and living skin surrounding a black hair sample after irradiation.</figref><figref num="8B">FIG. 3 is an oscilloscope diagram showing the time-corresponding temperature of dry black hair, wet black hair, and living skin surrounding a black hair sample after irradiation.</figref><figref num="8C">FIG. 3 is an oscilloscope diagram showing the time-corresponding temperature of dry black hair, wet black hair, and living skin surrounding a black hair sample after irradiation.</figref><figref num="9">FIG. 5 is a plot showing temperature rise with laser pulse energy as a function for specimens of dry hair (DH), wet hair (WH), and skin (S) of eight different patients.</figref><figref num="10A">FIG. 3 is a partial cross-sectional view of an applicator of the present invention used in the embodiment of an alternative embodiment of the present invention, in which a hair removal treatment is performed before irradiation and an empty hair sac is filled with a chromophore.</figref><figref num="10B">FIG. 6 is a cross-sectional view of an applicator of an alternative embodiment used for hair removal.</figref>

Code description

10 Hair remover 12 Light source 16 Fiber optic cable 18 Irradiator 42 Lens 46 Contact device 46 ́ Applicator 50 Cooling water inlet 52 Cooling water outlet 110 Slot