FR2924597A1 - PROCESS FOR TREATMENT OF KERATINIC FIBERS, INCLUDING THEIR EXPOSURE TO LIGHT LIGHT PULSES. - Google Patents

Abstract

The present invention relates to a process for treating keratin fibers, comprising the step of subjecting the fibers to light pulses of duration less than or equal to 5 10 <-12> s, emitted by a treatment device.

Description

The present invention relates to processes for treating keratin fibers, human or animal, by exposure to light pulses of short duration. It is known to permanently bleach hair by exposing it to light pulses of short duration having a relatively high peak power. Publication EP 685220 thus discloses a process for bleaching the hair by irradiation with a neodymium YAG laser, the duration of the pulses being able to range, for example, from 10 to 100 ns. The publications EP 682937, EP 685180 and US 2007/0167936 disclose other methods and devices for treating keratin fibers using lasers. The choice of the irradiation parameters is critical because, if one leaves the required conditions in terms of pulse duration and peak power, the discoloration of the melanin of the hair may no longer take place or the hair may become too hot. and degrade to the point of burning. The range of fading efficiency of the lasers used in the above publications is not very large and therefore there is a not insignificant risk of going out thereof. Some lasers pumped by flash give pulses ranging from tens of ps to several tens of ns. These lasers provide a high excitation energy but impose relatively low firing rates, of the order of Hz to a few tens of Hz. Certain lasers pumped by diode of the Q-switched type (or according to the English terminology Q -switched) have pulse durations ranging from 100 ps to about 1 s. The diode pumping brings lower pulse energies than the flash pumped mode but allows higher rates. As a result, each pulse can only treat a relatively small area, but this drawback can be compensated for by scanning the area to be treated, made possible by the higher rate.

There is a need to further improve the methods for treating keratin fibers with lumen and, for example, to further reduce the risk of going outside the range of effectiveness. The invention aims, according to one of its aspects, to meet this need, and it achieves this by means of a process for treating keratin fibers comprising the step of subjecting the fibers to pulses of light, in particular of light. visible, infrared or ultraviolet of duration less than or equal to 5.10 12 s, better still 2.10 12 s, emitted by a treatment device. The latter advantageously comprises a laser. The treatment is, for example, a treatment for bleaching the hair, which may have its natural color or be colored artificially, with a view to a new coloring or a return to the natural color. The treatment according to the invention can also be used to treat the hair for effects other than bleaching, for example to carry out transformations of the keratin (rearrangement or transformation of proteins, at the primary, secondary or tertiary level), with effects by example on the shape, on the softness and / or on the shine One can focus the light on the surface of the hair, in order to obtain a very important local energy, with a spatial resolution which can be very fine, for example of the order micron. The result of these impacts is a transformation of the keratin at the single point where the impact took place.

If we focus the light on the surface of the hair, we can modify the surface without damaging or transforming the core or the entire hair. This may allow the surface to be planed for smoothness or shine, or it may allow the creation of rough edges or patterns. By focusing the laser light in the form of a multitude of small dots (of the order of a micron for example) one can obtain an effect of modification of the touch or styling properties, for example the propensity to curl, to disentangle , their stiffness .... If we focus inside the hair, we can heat locally and modify the keratin without modifying or altering the surface. This can allow the keratin to locally melt to gain strength or rigidity or to repair damaged fibers. The treatment can be carried out so as to increase the porosity of the fibers. This, especially in the case of natural hair, can be advantageous because certain fibers are hardly permeable to exogenous compounds such as dyes for example. Exposure to laser radiation can be aimed at modifying proteins and cauterizing hair, hair tips, split ends, and even hair ends. The invention can also be implemented to cut the hair. The treatment may relate to at least one lock of hair, for example at least ten locks of hair, for example each at least 10 cm long and at least 0.5 cm wide, or the whole of the hair or more local areas.

The treated keratin fibers may or may not be dry, for example wet or wet. The treatment can also concern the eyelashes, eyebrows or hair covering the face or body. By visible light, it should be understood that the spectrum of the light received by the keratin fibers contains at least one wavelength in the 380-750 nm range. The pulses received by the keratin fibers can comprise at least one dominant wavelength in one of the ranges 1000-1600nm, 700-900nm, 350-450nm or 500-800nm. The term pulse duration denotes the time a during which the light power reaching the keratin fibers is greater than or equal to half of its peak power Pc, as illustrated in FIG. 1. The number of light pulses at which the same region of the keratin fibers may be exposed may depend on the surface energy of the radiation which reaches the keratin fibers, on the color of the latter and on the treatment to be carried out, for example on the degree of discoloration desired. Treatment of keratin fibers by local exposure to several successive pulses can prove to be advantageous, since it allows in particular a more gradual bleaching treatment and can further reduce the risk of damage to the keratin fibers. It may not be necessary to project a cooling gas flow onto the keratin fibers.

The duration of a pulse can be between 10 15s and 5000 10 15s, better 1015 s and 1000 10 15 s, even better between 10 10 15s (10 femtoseconds) and 800 10 15 s (800 femtoseconds), with a frequency which is for example greater than or equal to 100 Hz, better still 1 kHz, even better 1 MHz.

The pulses can be emitted at a frequency which depends, for example, on the laser used and on the possible scanning speed of the keratin fibers. Obtaining light pulses of short duration can be done, for example, by using a broadband laser, associated with a mode blocking device, capable of blocking a large number of modes of the laser cavity with good stability of the laser cavity. phase, for example a laser, the amplifying material of which is titanium-sapphire or a material doped with erbium or ytterbium, in the form of a fiber or of a crystal. The light received by the keratin fibers is advantageously non-monochomatic, the spectral width of the pulses received by the keratin fibers being for example greater than or equal to 200 nm. In some cases, the bandwidth can be even greater, and range for example from infrared to UV A relatively broad spectrum can be useful to enhance the efficiency of the process, when the compounds that one wishes to achieve in and / or on the keratin fibers have a relatively wide absorption band, which is the case for example with melanin and may be the case with other dyes introduced beforehand onto the keratin fibers. The treatment device may include a nonlinear optical device associated with the laser in order to broaden the emission spectrum of the radiation emitted by the laser. As mentioned above, a relatively broad spectrum can improve the effectiveness on melanin in particular. The spectrum received by the keratin fibers can thus be broadened, in an exemplary implementation of the invention, to the point of going from ultraviolet to infrared and producing a light which appears white. A relatively broad spectrum can also be advantageous in that it makes it possible to treat colored hair, containing melanin and at least one other dye, since these compounds can then be achieved simultaneously.

The nonlinear optical device may include a photonic crystal optical fiber, for example.

The processing device may include a frequency doubler associated with the laser, in particular when the latter emits in the infrared. Where appropriate, the treatment device can be tunable in wavelength.

The light emitted by the treatment device can be centered on a wavelength in the range of 400 nm to 440 nm, in which melanin absorbs particularly well. The laser from which the pulses are generated can be a titanium-sapphire laser and can advantageously be associated with a frequency doubler, which makes it possible to obtain pulses centered around 400nm. The treatment device can include a device for collimating the light beam emitted by the laser, which can make it possible to use a less powerful and therefore less expensive laser while reaching an energy level sufficient to selectively destroy the melanin or any other. compound or obtain the desired reaction. Where appropriate, the collimation device can be adjustable, in order to allow adjustment of the surface density of energy reaching the keratin fibers, this adjustment being carried out for example as a function of the initial color of the keratin fibers to be treated or of the degree desired discoloration. The collimation device can be manually or automatically adjustable. The processing device can thus comprise a lens associated with the laser, for example a lens having a numerical aperture of between 0.1 and 1. Lenses having such digital apertures are, for example, known from certain recent devices for reading disc discs. optical storage. It is possible to use a laser whose average electric power is for example between 0.001 W and 50 W. Given the speed of each pulse, the lasers useful for the invention can deliver peak powers ranging from 100 MW to 100 GW. The pulses useful in the invention have for example a surface energy (energy density) of the order of one joule per cm 2. Depending on the yields, the pulse durations, and the hair, this surface energy can vary from 0 , 01 J / cm2 to 10 J / cm2 for example. Low power can facilitate the realization of a treatment device operating with an autonomous energy source, such as batteries or accumulators.

The target surface illuminated by a pulse may have a greater dimension greater than or equal to 0.1 m and / or less than or equal to 100,000 m. The keratin fibers and the treatment device can be given a relative movement during the treatment.

The keratin fibers can be treated in a single pass or in several passes. The process according to the invention may comprise the application of a composition to the keratin fibers before exposure to the light pulses, for example a composition comprising: a) at least one oxidant or reducing agent. These compounds do not necessarily enter the laser impact process but can be used to supplement discoloration by specifically attacking artificial dyes, for example. b) at least one colorant. The latter can be applied at the same time as the laser impact, or just before or after, which saves time in the overall treatment. For example, a dye is applied substantially simultaneously with the laser radiation exposure. As a result, the hair comes out colored and the melanin discolored. Therefore, the coloring is particularly noticeable. Another subject of the invention, according to another of its aspects, is a device for treating keratin fibers, comprising: - a light source designed to emit light pulses of duration less than or equal to 2 10 12 s, - a system allowing the impulses to be directed towards the keratin fibers to be treated. This system may include a handpiece, for example.

The source may include a laser, in particular a so-called femto laser emitting light pulses the order of magnitude of the duration of which is from 1 femtosecond to 10 pico seconds. An advantage linked to the use of a femto laser for the treatment of keratin fibers is the fact that, due to its small geometric extent (product of the surface and of the solid angle of emission), the beam can be collimated. on a very small surface. This makes it possible to concentrate the energy on very small areas and therefore to use a laser with a relatively low average power and / or with a relatively low energy per pulse, hence advantages in price, consumption and clutter. This low energy can be compensated by a large sweep of the surface of the wick, which is possible because femto lasers make it possible to reach rates up to GHz in certain configurations, and this without losing the quality of the duration of the pulses. . Crystal-based femto lasers are well suited to these high rates. The laser used in the treatment device is for example a laser having a cavity formed by two mirrors located on either side of a broadband amplifier material, in particular titanium-sapphire or ytterbium, and a mode blocking device . The pump light can be produced by at least one flash lamp or at least one diode. The laser may also include a cavity formed by a fiber of an amplifying material, for example titanium-sapphire or ytterbium, a coupler for injecting the pump light, a coupler for extracting the laser pulses and a blocking device. fashion. The pumping light is advantageously produced by at least one diode, but as a variant this light is produced at least by a flash lamp or a laser. The processing device may include a non-linear optical device receiving the light from the laser, comprising for example a photonic crystal fiber.

The treatment device may include a frequency doubler receiving the light emitted by the laser. The treatment device can be arranged to determine at least one of the number of pulses that must reach the zone to be treated, of the frequency of the pulses and of the surface energy per pulse, as a function of the initial color of the keratin fibers to be treated. treat. Thus, the darker the hair, the higher the number of pulses and / or the surface energy per pulse can be. The treatment device can also be arranged to determine, automatically, at least one of the number of pulses, of the frequency of the pulses and of the surface energy per pulse, as a function of the desired color after treatment.

Thus, the less the discoloration, the lower the surface energy can be. The treatment device may include a color analysis device to assist in the discoloration treatment. This color analysis device can be used, for example, to determine the color of the keratin fibers before treatment, in order for example to determine the number of light pulses necessary to achieve the desired discoloration of a given area of the keratin fibers. The brighter the fibers, the lower this number of pulses can be.

The color analyzer can still be used to determine when a predetermined degree of discoloration is reached. Indeed, after each pulse, the fibers are a little more discolored, so that by analyzing the color of the fibers during the treatment, it is possible to detect when the desired color is reached. The device for analyzing the color of keratin fibers can thus be useful for preventing a new exposure to the light pulses of keratin fibers for which the device for analyzing the color indicates that they have already been sufficiently discolored. The color analysis device may include, for example, a color camera or any other suitable detector.

The shape of the light spot reaching the keratin fibers during the emission of a light pulse can be circular or polygonal, for example substantially square or rectangular, or the like. A polygonal shape may prove to be advantageous in order to allow complete scanning of an area to be treated, by juxtaposition of the light spots.

The successive exposure to the light pulses of at least two zones to be treated different from the keratin fibers can be carried out in various ways. The light pulses can be emitted for example by a treatment head which is moved relative to the keratin fibers when one passes from the treatment of a first zone to the treatment of a second zone. The emission of light pulses can then be triggered as a function of the displacement of the treatment head relative to the keratin fibers, for example in order to prevent one and the same region of the keratin fibers from receiving more than a predefined number of pulses, each time the treatment head passes through the keratin fibers to be bleached. The treatment head can be moved relative to the keratin fibers manually, the treatment head belonging to a handpiece. Alternatively, the processing head can be moved relative to the fibers in an automated fashion.

The treatment device can for example comprise at least one actuator, for example a robot, making it possible to move the treatment head relative to the keratin fibers. The laser may or may not be rigidly linked to the treatment head. The laser can in particular be optically connected to the treatment head by a hose. The latter can include at least one optical fiber. Whether or not the treatment head is fixed for the duration of the treatment of a given area, the direction in which the light pulses are emitted relative to the keratin fibers can be varied. Such a sweeping movement, by modifying the orientation of the bundle directed towards the keratin fibers over time, can be combined, where appropriate, with a displacement of the treatment head relative to the keratin fibers, along the latter. . Scanning can also be carried out, for example, without necessarily modifying the orientation of the light beam directed towards the keratin fibers, by using a sheet of juxtaposed optical fibers, illuminated sequentially. Whatever the way in which the scanning is obtained, this can for example take place in a first direction and the displacement of the treatment head relative to the keratin fibers take place in a second direction, substantially perpendicular to the first. The scanning speed in the first direction may depend on the scanning speed in the second direction and vice versa. At least two different regions of the keratin fibers can be treated differently. The bleaching can thus take place in a non-uniform manner on the keratin fibers, in order to create effects. The fading can for example take place in discrete regions, which can be arranged as screen dots, for example. It is thus possible to selectively expose the keratin fibers in order to produce a screened pattern. The discoloration can be done in a checkerboard pattern or in other patterns. It is also possible to interpose, on the path of the light, a mask making it possible to form a pattern having a predetermined contour on the keratin fibers. The keratin fibers can be coated with a composition forming a screen for the light pulses at the locations which it is not desired to treat, for example a composition comprising one or more inorganic materials such as pigments, aluminas, silicas, nitrides, carbides, carbonates. , compounds based on titanium or silicon. One or more organic or mixed materials such as polymers, gels or fluids, which may or may not contain pigments.

Such a composition can be cold (at least 5 ° C below room temperature) or very cold (at least 20 ° C below room temperature). The scalp and / or skin can also be coated with a screening composition, for example a composition comprising at least one of the compounds listed above. The keratin fibers can also be coated with compositions promoting the treatment, for example a gel reducing losses by reflection of light at the fiber / air interface. The composition can, for example, extend continuously between the optical medium of the treatment device where the light pulses and the keratin fibers propagate. Such a treatment promoting composition can be deposited on the hair so that the path of the light is made more rectilinear. Preferably, this composition has a refractive index if possible close to that of the hair. It is also preferable that the composition sticks to the hair and forms a flatter surface than the hair itself. The composition promoting the treatment may comprise a gel, for example carbopol, a guar gum, etc., or an inorganic or organic liquid, for example a silicone, a vegetable or paraffin oil, etc. It is also possible to achieve a desired degree of discoloration by only partially treating the keratin fibers, so that regions having different degrees of discoloration are juxtaposed. These regions which present different colors on a microscopic scale may, when observed at a certain distance, no longer be individually discernible with the naked eye and generate by chromatic mixing an intermediate color. A bleaching fade can be achieved on hair, for example by changing the spatial frequency and / or the size of regions bleached by exposure to light pulses.

Once the bleaching has been carried out, it is then possible, where appropriate, to color the keratin fibers. In the case of the treatment of a hair, after having bleached a lock, it is possible to keep the latter isolated from the rest of the hair for the time to carry out the coloring of the lock. The treatment device may include a detection device making it possible to verify the presence of keratin fibers in front of the treatment head and be designed to prevent the emission of light pulses in the absence of keratin fibers. The treatment device may be arranged to shield light outside of a treatment space, and include means to prevent light leakage beyond the treatment space. It may for example be a flexible seal, a row of bristles or a baffle. The treatment device may comprise, for example at the level of the handpiece, two parts movable with respect to one another, for example in the form of branches, arranged to close on the keratin fibers. The treatment space is defined between these mobile parts, which are for example articulated to each other. The processing device can be arranged to detect the closure of the processing space and only authorize the emission of light pulses if this condition is satisfied. The treatment device comprises for example a switch 20 actuated when the treatment space is closed. The treatment device may include reliefs, for example teeth, arranged to emit light towards the keratin fibers. The light can come out between the teeth. The treatment device can be arranged to detect a relative displacement of the keratin fibers and of the treatment head and only allow the emission of the pulses in the event of movement, in order to avoid excessive burning or discoloration of hair when stationary. The treatment head may include an application member capable of applying a substance to the keratin fibers, for example to a lock of hair. This applicator member comprises, for example, an ink pad. The treatment head can be arranged so that the application of the aforementioned substance by the application member takes place after exposure of the keratin fibers to the light pulses. The substance can be a hair coloring product or a care product. The treatment head may include means for combing a lock of hair before and / or after the introduction of the latter into the treatment head.

The invention may be better understood on reading the detailed description which follows, of non-limiting examples of its implementation, and on examining the appended drawing, in which: FIG. 1, already described, schematically represents the evolution of the power of a pulse received by the keratin fibers as a function of time, FIG. 2 is a schematic and partial view of a treatment device in accordance with the invention, - FIG. Figure 3 illustrates schematically and partially the use of the treatment device of Figure 2, - Figures 4 and 5 are respectively longitudinal and transverse sections along VV, schematic and partial, of the treatment head of the device of Figure 2, - Figure 6 illustrates the sweeping of a lock of hair, - Figures 7 to 9 are views, schematic and partial, of variants of treatment heads according to the invention, and - Figures 10 to 12 are cross sections, sch ematic and partial, other variants of treatment heads according to the invention. The keratin fiber treatment device 1 shown in FIG. 2 comprises a base station 2 and a handpiece 3 connected to the base station. The handpiece 3 is arranged to receive a lock M of hair to be treated 25 and to expose the hair to the light pulses in a treatment space, as illustrated in FIG. 3. The base station 2 can include all or part of the means. necessary for generating the light pulses intended for the treatment of keratin fibers, and in particular comprising a pulsed light source such as a laser. The handpiece 3 can be connected to the base station by at least one flexible tube 4 making it possible to route the light pulses to the keratin fibers, comprising for example one or more optical fibers.

As a variant, the light pulses are emitted from the handpiece 3, the base station 2 comprising for example an electric power supply and a system for controlling the operation of the handpiece 3. In a further variant, the base station 2 n 'does not exist and the treatment device is fully integrated into the handpiece 3. The treatment device 1 can also be produced without a handpiece 3, for example in the form of a cabin in which the device is placed. user, the irradiation of the hair taking place at a distance, the hair possibly having been previously prepared for the treatment, for example placed on a suitable support.

The handpiece 3 may include, as illustrated, a handle 6 and a push button 7 making it possible to trigger the emission of light pulses. The handpiece 3 incorporates a treatment head which may include an optical deflector making it possible to deflect the light that it receives in order to scan at least a fraction of the area to be treated. This optical deflector may include a movable mirror, in particular an oscillating mirror. The flexible 4 can include one or more electric cables making it possible to exchange information between the handpiece 3 and the base station 2. The flexible 4 can include a cable making it possible to convey to the base station 2 a signal representative of pressing button 7.

The treatment device may include a collimation device (also called a focusing device) placed on the path of the light between the light source and the keratin fibers to be treated, in order for example to increase the surface energy of the directed light beam. on keratin fibers and / or allow adjustment of the energy surface density.

Such a collimation device is for example incorporated in the handpiece, which may for example be located upstream of the optical deflector. The collimation device comprises for example a converging lens, for example a numerical aperture of between 0.1 and 1, but it is not beyond the scope of the present invention when the collimation device is different and comprises one or more converging lenses. or divergent or others. The processing device 1 may include calculation means 13, a screen 14 and a keyboard 15, as illustrated in FIG. 2.

The keyboard 15 can for example make it possible to enter the initial color of the fibers, the desired degree of discoloration or the desired final color after discoloration, but other acquisition means can be used, for example a scanner 16 or a camera. The computing means 13 may include a microcomputer or other computer or electronic means. The calculation means 13 can be arranged to act on the emission of the light pulses, in particular their triggering, their frequency and / or their power, as well as on the possible optical deflector, in particular its orientation, on the possible focusing device and / or. or process information coming from the handpiece, this information coming for example from the button 7, from a possible camera arranged in the handpiece or being linked to other sensors integrated in the latter, for example to detect the movement of the hair relative to the handpiece 3. The calculation means 13 can be programmed to automatically determine at least one of the number of pulses, the frequency of the pulses and the surface energy per pulse, as a function of example of the final color of the fibers after bleaching and / or of the initial color of the fibers. The screen 14 can make it possible to visualize before the treatment the hair which will be obtained after the treatment, for example in the form of a 2D or 3D image. The calculation means 13 can also make it possible to select an image of a desired hair and determine the treatment to be carried out on the hair in order to obtain hair conforming to the selected image, in particular when it is a question of producing a pattern. on the hair. The pattern selected can be in a library of images stored in a memory, or come from reading a photograph, for example by means of the scanner 16. It is thus possible, for example, to acquire by means of the scanner 16 an image , for example a logo, and draw this logo on the hair by selectively bleaching it. In the example illustrated, the calculation means 13 are external to the base station 2, but these can also be integrated at least partially into the base station or into the handpiece in variants not illustrated. The laser of the treatment device allows the production of light pulses of very short duration, in particular less than 5.10 12 s.

In an exemplary implementation of the invention, the laser used is an optical fiber laser such as, for example, that marketed by the German company Toptica Photonics AG under the reference FFS Ultrafast erbium fiber laser system, comprising an FFS oscillator. bu Base Unit, an FFS.sys amplifier, an FFS.tshg adaptable frequency doubler and an FFS.cont continuous light generator. In this example, a collimator can be placed at the exit of the beam in order to obtain zones of approximately 2 m in diameter on the hair. Before collimation, the beam can be sent to an optical deflector, the scanning speed being for example 100 Hz.

Such a laser is capable of emitting at a rate of 100 MHz, each pulse having a duration of about 100 femtoseconds and the spectral coverage of the device extends from about 525 to 700 nm. Such a range corresponds not to that of the light which comes out of the laser itself but to the light which comes out of the device, it being understood that these are the module (s) arranged after the laser (modules dispersion, compression and doubling) which lead to this range. The treatment device using this laser makes it possible to treat dark locks in one second per 100,000,000 points of 2 m in diameter, or approximately 400 mm2. In another exemplary embodiment of the invention, the laser used is that marketed under the reference Femtoregen IC 1035-1000 FS HE Reg Amp by the Austrian company High Q Laser. At the output of such an ytterbium crystal laser, it is possible to place a frequency doubler, an optical deflector and a collimator until zones of 100 m in diameter are obtained per pulse. The laser is capable of emitting at a frequency of 1 kHz, each pulse having a duration of about 400 femtoseconds and a dominant wavelength of about 515 nm.

The treatment device comprising such a laser makes it possible to treat dark locks in one second per 1,000 points of 100 m in diameter, ie approximately 10 mm 2. Another example of a very short duration pulsed laser is offered by the company Amplitude System, Pessac, France, under the reference Laser t-pulse 200 and allows scanning at a frequency of 100 Hz over an angular range of +/- 10 °.

In another example, a laser from the French company Thales Laser known under the name BRIGHT ULTRAFAST KHZ SERIES is used. This laser emits pulses of approximately 120 femtoseconds duration, with an energy per pulse of approximately 1.5 mJ, at a rate which can range from 1 pulse to 5000 pulses per second. The light is centered around 780 nm. A frequency doubling module (Thales Laser) is added to the laser, which can bring, if this module is connected, to a frequency centered around 390 nm.

The device comprises an objective making it possible to adjust, by focusing, the surface energy and the size of the spot. A second optical filter device makes it possible to adjust the surface energy without modifying the size of the spot. Hair is irradiated with this device and depending on the circumstances, hair zone bleaching effects or keratin modifying effects can be obtained with small dots melted into the surface of the hair. The handpiece 3 can have various configurations making it possible to expose the keratin fibers to the treatment light. The handpiece 3 may include any means for receiving and guiding the hair, for example, as seen in FIG. 2, a groove 10 formed between an upper branch 12 and a lower branch 13, defining the space of treatment. The branches 12 and 13 may be fixed relative to one another or, in a variant, may be arranged so as to move apart like a clamp for example, in order to facilitate the positioning of the keratin fibers between them. treat. The closing of the branches can be detected in order to prevent the emission of the pulses in the event of failure to close the branches. Screen-forming means can be arranged between the branches on either side of the treatment space, to oppose light leaks, for example a flexible seal, a row of bristles or a baffle. At least one of the branches, for example the lower branch, may comprise on its face facing the other branch an exit window 14 allowing light to reach the fibers to be treated, as illustrated in FIGS. 4 and One or more mirrors 15 or other light guiding elements may be arranged inside the handpiece 3, so as to appropriately orient the light pulses in the direction of the exit window 14.

The handpiece 3 may have only a single exit window 14 on one of the branches, and the other branch then constitutes a screen making it possible to absorb the residual light passing through the wick M. As a variant, the piece to be hand 3 can include means for simultaneously exposing to the light pulses at least two opposite faces of the wick M. The handpiece 3 can include for this purpose a second exit window on the upper branch, facing the lower branch, and means making it possible to divide the laser radiation into two beams, so that the light pulses are emitted from each branch towards the keratin fibers. These means can comprise for example at least one semi-reflecting surface or several optical fibers. Where appropriate, each branch is alternately supplied by the light to be projected onto the fibers. To supply the branches alternately, the aforementioned optical deflector can for example deflect the light alternately towards one then the other of the branches, or alternately towards two optical fibers leading the light to the exit windows. The keratin fibers are scanned by the light beam coming from the treatment head, for example, in the direction D1 perpendicular to the direction of displacement D2 of the handpiece relative to the wick M, as illustrated in FIG. 6.

Depending on the ratio between the scanning frequency and the emission frequency of the light pulses by the laser, the same region of the keratin fibers may be successively exposed to more than one light pulse during a scanning cycle. The number of pulses to which a same region is exposed can be determined as a function of the surface energy or vice versa, for example by using laws which can involve the frequency of emission of the light pulses by the laser. The discoloration of the keratin fibers may or may not be uniform. The treatment device can, for example, be designed to send light pulses only to certain areas of the keratin fibers during each scanning cycle, so as to bleach at least two keratin fibers therein differently.

It is for example possible to lighten only certain regions of the keratin fibers so as to obtain an intermediate rendering between the initial color of the lock and white. It is also possible to achieve a gradation of discoloration on the hair.

To obtain a fading gradient along the strand, it is possible, for example, to increase the surface density of energy received by the keratin fibers during the movement of the treatment head along them, for example by acting on a la pulse frequency. It is also possible to perform several passages and make the number of passages depend on the position on the hair. It is also possible to vary the speed with which the handpiece 3 is moved relative to the keratin fibers, a slow movement being able to expose the keratin fibers to a greater energy than a rapid movement. It is also possible to vary the dimensions of discolored regions alternating with non-discolored regions. FIG. 7 schematically shows a variant of a handpiece 3 comprising a groove for receiving the fibers to be treated formed on a single branch. In this example, the handpiece 3 does not have a screen making it possible to absorb the residual light passing through the wick M. In the example of FIG. 2, the handpiece 3 is moved manually relative to the hair, but one does not depart from the scope of the present invention if the treatment head is moved relative to the keratin fibers in an automated manner. By way of example, FIG. 8 very schematically shows a treatment head connected to an actuator 20 making it possible to move it relative to the hair. The treatment device may include means for combing the lock M before and / or after exposure to the treatment light, these combing means possibly comprising reliefs transparent to the treatment light. The handpiece may in particular include one or more teeth 24 or other reliefs placed before and / or after the treatment space, as illustrated schematically in FIG. 10.

The emission of the pulses can be controlled as a function of the displacement of the treatment head relative to the hair. The handpiece 3 may include means making it possible to determine the speed of movement of the wick M exposed to the light pulses relative to the treatment head. These means may comprise at least one rotary member rotating under the effect of the displacement of the wick M in the treatment head in order to allow the treatment device to automatically calculate, as a function of this displacement speed, the power and / or the number and / or the frequency of the light pulses and / or to synchronize the triggering of the pulses with the displacement of the wick M. By way of example, FIG. 11 shows a treatment head comprising two opposed rollers 30 capable of rotating in contact. of the bit M introduced between them. The rotation of the rollers 30 is measured and the processing device may include calculation means adapted to act on the emission of the light pulses as a function of this rotation. The treatment device may also include means for not subjecting the same region of fibers twice to more than a predefined number of pulses when the handpiece 3 is stationary relative to the keratin fibers, so as not to damage these fibers. last. The treatment device 1 can, for this purpose, comprise at least one device for measuring the color of the fibers. In the example illustrated in FIG. 12, the color of the keratin fibers is determined in real time or almost using a camera 40 housed in the treatment head, and which has been shown very schematically. Of course, it does not depart from the scope of the present invention if this camera 40 is replaced by any other suitable color detector. The image produced by the camera 40 is for example analyzed in order to determine the degree of discoloration of the keratin fibers. When the desired degree of discoloration is reached, the light pulses are no longer emitted. The camera 40 can also be used to verify the presence of a lock M to be treated or to determine the speed of movement of the keratin fibers relative to the treatment head, by analyzing the speed of movement of the border between the discolored and non-discolored regions. , relative to the treatment head. The treatment device can be arranged so as to be able to color the hair as the lock M is moved.

The handpiece 3 may include for this purpose an application member 50 comprising for example an ink pad making it possible to deposit a coloring product on the wick M, as illustrated in FIG. 9. This ink pad is carried by a support which does not hinder the passage of the lock M between the branches 12 and 13. A product other than a coloring product can be applied upstream of the treatment space, for example a product facilitating the sliding of the hair. A product which is insensitive to the wavelength of the light received by the keratin fibers or on the contrary activated by this light can also be applied to the fibers before the bleaching treatment, for example to facilitate the latter or to obtain a particular coloring. Alternative embodiments of the invention (not illustrated) can combine characteristics originating from the various exemplary embodiments which have just been described. Another subject of the invention, according to other aspects, is the use of light pulses emitted by a laser for carrying out certain treatments of keratin fibers, the pulses emitted by the laser being as defined above or having other characteristics. temporal or spectral, the pulses being sufficiently short and intense to provide the desired result. According to these other aspects: - keratin fibers can be subjected to pulses focused at the core of the fibers, - keratin fibers can be subjected to pulses in order to modify their porosity and / or their mechanical properties, in particular the styling properties, - the fibers keratin fibers can be subjected to pulses in order to modify their shine, for example in order to smooth their surface, - keratin fibers can be subjected to pulses to repair damaged fibers, - keratin fibers can be subjected to pulses to modify their appearance to the touch , or - the keratin fibers can be subjected to pulses in order to cauterize them, in particular cauterize their tips, split ends or the ends of the split ends.

The expression comprising one should be understood as a meaning comprising at least one, unless specified to the contrary.

Claims (43)

1. Process for the cosmetic treatment of keratin fibers, comprising the step of subjecting the fibers to light pulses of duration less than or equal to 5 10'12 s, emitted by a treatment device (1). 2. Method according to claim 1, the duration being between 10 "15 s and 1000.10'15s. 3. Method according to one of the preceding claims, the duration being between 10.10-15 s and 800.10-15 s. 4. Method according to any one of the preceding claims, the spectral width of the pulses emitted being greater than or equal to 1 nm. 5. Method according to any one of the preceding claims, the pulses comprising at least one dominant wavelength in one of the ranges 1000-1600nm, 700-900nm, 350-450nm and 500-800nm. 6. Method according to any one of the preceding claims, the treatment device (1) comprising a laser. 7. Method according to the preceding claim, the processing device comprising a non-linear optical device associated with the laser in order to widen the emission spectrum of the radiation emitted by the laser. 8. The method of claim 7, the non-linear optical device comprising a photonic crystal optical fiber. 9. Method according to any one of claims 6 to 8, the processing device comprising a frequency doubler associated with the laser. 10. A method according to any one of claims 6 to 9, the light emitted by the laser being centered on a wavelength located in the range from 400 nm to 440 nm. 11. A method according to any one of claims 6 to 10, the laser being a titanium-sapphire laser. 12. Method according to any one of claims 6 to 11, the processing device comprising a lens associated with the laser. 13. Method according to the preceding claim, the lens having a numerical aperture of between 0.1 and 1. 14. Method according to any one of the preceding claims, the peak power of each pulse being greater than or equal to 0.001 W. 15. Method according to any one of the preceding claims, the pulses being emitted at a frequency greater than or equal to 1 MHz. 16. Method according to any one of the preceding claims, the surface illuminated by each pulse having a greater dimension greater than or equal to 0.1 lam. 17. Method according to any one of the preceding claims, the surface illuminated by each pulse having a greater dimension less than or equal to 100,000 m. 18. Process according to any one of the preceding claims, in which the keratin fibers and the treatment device are given a relative movement. 19. The method of claim 18, the keratin fibers being treated in a single pass. 20. The method of claim 18, the keratin fibers being treated in several passes. 21. Method according to any one of the preceding claims, the keratin fibers being subjected to the pulses in order to bleach them. 22. Method according to any one of claims 1 to 21, the keratin fibers being subjected to pulses focused on their surface. 23. Method according to any one of claims 1 to 21, the keratin fibers being subjected to pulses focused at the core of the fibers. 24. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to modify their porosity. 25. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to modify their mechanical properties, in particular the styling properties. 26. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to modify their brightness. 27. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to smooth their surface. 28. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses to repair damaged fibers. 29. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to modify their appearance to the touch. 30. Method according to any one of claims 1 to 20, the keratin fibers being subjected to pulses in order to cauterize them, in particular cauterize their tips, forks or the ends of the forks. 31. Method according to any one of claims 1 to 30, comprising the application of a composition to the keratin fibers before their exposure to the light pulses. 32. Method according to any one of claims 1 to 30, comprising the application of a composition to the keratin fibers during their exposure to the light pulses. 33. Method according to any one of claims 1 to 30, comprising the application of a composition to the keratin fibers after their exposure to the light pulses. 34. Method according to claims 31 to 33, the composition comprising at least one compound inducing discoloration of the hair, in particular an oxidant or a reducing agent. 35. The method of claims 31 to 33, the composition comprising at least one compound inducing coloring of the hair. 36. Device for treating keratin fibers, comprising: - a source (12) arranged to emit light pulses of duration less than or equal to 5.10 "12 s, - a system (3, 4) making it possible to direct the pulses towards the keratin fibers to be treated. 37. Device according to claim 36, the source (2) comprising a laser. 38. Device according to claim 37, the laser comprising a cavity formed by two mirrors, a broadband amplifier material disposed in the cavity, and a mode blocking device. 39. Device according to claim 37, the laser comprising a cavity formed by a fiber of an amplifying material, a coupler for injecting the pumping light, a coupler for extracting the laser pulses and a mode blocking device. 40. Device according to any one of claims 37 to 39, comprising a non-linear optical device receiving the light from the laser. 41. Device according to claim 40, the non-linear optical device comprising a photonic crystal fiber. 42. Device according to any one of claims 36 to 41, comprising a frequency doubler receiving the light emitted by the laser. 43. Device according to any one of claims 36 to 42, comprising at least one composition to be applied to keratin fibers.