WO2002096311A1

WO2002096311A1 - Safe laser hair removal system with a protraction-retraction mechanism

Info

Publication number: WO2002096311A1
Application number: PCT/IB2002/001898
Authority: WO
Inventors: Tomoyuki Takahashi
Original assignee: Tomoyuki Takahashi
Priority date: 2001-05-30
Filing date: 2002-05-30
Publication date: 2002-12-05

Abstract

In accordance with the present invention there is provided a laser hair removal apparatus that is equipped with a protraction-retraction system that provides foolproof safety. The protraction-retraction mechanism is incorporated into the handpiece of a laser hair removal apparatus or into a hand held laser hair removal apparatus. It comprises a laser dispersion tube through which laser pulses travel onto the skin of the subject, which is disposed inside a tubular casing with a spring such that when not operational the handpiece or hand held apparatus is in a protracted position, in which position laser pulses are not fired. When the handpiece or hand held apparatus is pressed against the skin of the subject, the laser dispersion tube is placed in a retracted position, causing laser pulses to be fired onto the skin of the subject according to a pre-programmed sequence. The invention also provides methods for laser hair removal using the apparatus of the invention.

Description

SAFE LASER HAIR REMOVAL SYSTEM WITH A PROTRACTION-RETRACTION

MECHANISM

FIELD OF THE INVENTION

This invention relates to an apparatus and method for hair removal and particularly to a safe, convenient, easy to use laser system for removal of hair.

BACKGROUND OF THE INVENTION Historically, hair removal techniques have ranged from inexpensive plucking with forceps to expensive techniques such as electrolysis. Electrolysis, which falls in the category of so-called permanent hair removal techniques, is performed by first attaching an electrode to each individual hair root, and then passing an electric current through the hair root and the hair follicle through the papilla. This precisely directed current induces permanent injury in the follicle and papilla, stopping the future production of the hair root. However, electrolysis remains an expensive procedure, which is slow and often causes great discomfort to the subject on account of the electric current.

Over the last few years, hair removal by lasers has emerged as an attractive alternative to electrolysis. Commercial embodiments of laser hair removal systems have been available since 1996. Lasers allow the rapid removal of large areas of hair, veins or capillaries on almost any body area, such as on the face, arms, legs, breasts, hands, stomach and the like. Further, laser treatment provides an unusually low discomfort level to the subject, and hair removal may last for weeks on a body area.

Many of the hair removal lasers work by application of the principal of selective photothermoloysis, i.e. selective destruction due to heat caused by absorption of light. Laser light, which has a single wavelength, is optimally absorbed by a target which has a complementary specific color. This laser target is called a chromophore. The usual chromophore for hair removal lasers is melanin, found in high concentration in brown and black hair, and is responsible for the color of hair. Examples of lasers used for hair removal include the ND:YAG laser, the first commercially available laser, the ruby laser that emits a fixed wave length of 694 nm and the alexandrite laser that emits a fixed wave length of 755 nm. Lasers with wave lengths in the range of about 650 to about 900 nm appear to be the most effective in achieving permanent hair removal.

Pulsed flashlamps that emit filtered visible light having wave lengths of about 550 nm have also been used for permanent hair removal. For example, U.S. Pat. No. 5,683,380 to Eckhouse discloses a method and apparatus for removing hair (depilation) using a single high intensity pulsed flashlamp (not a laser) which emits a broad spectrum of pulsed incoherent light that is polychromatic.

Various approaches have been taken to implement laser hair removal technologies. One technology relies on a pulsed laser source and the use of an exogenous absorber. A commercially available hair dye solution is first applied to the skin containing the unwanted hair and allowed to migrate along the hair roots and into the follicles. The skin is then irradiated with a spot size of approximately 0.5 centimeters using a Q-switched YAG laser, or other short pulsed laser system.

The pulse durations used by the lasers tend to be short, 15 nsec for the Q-switched laser. It appears that the sub-microsecond pulse durations shocks the hair follicle, which stops hair production.

The Cynosure® laser system takes another approach called Thermokinetic Selectivity™.

This means the selective destruction of the target with the same chromophore as the skin (i.e. melanin), due to less efficient heat conduction out of the hair (as compared with the epidermis).

This less efficient heat conduction is due to a variety of factors, the main one being the unfavorably large volume to surface area of the hair. The Cynosures® laser, like the ruby lasers, uses a single pulse, but the pulse used by this alexandrite laser is longer (5-20 ms). This longer pulse allows more gradual accumulation of heat by the skin, so the heat has time to dissipate

(cool) and to prevent burning of the skin.

Another approach uses laser light delivery systems that inject light into only a single hair follicle at a time, thereby reducing concern for damaging tissue between hair follicles.

Several patents have been granted on the use of lasers for hair removal. For example,

U.S. Pat. Nos. 5,630,811 and 5,658,323 to Miller disclose a method and apparatus for dermatology treatments for lesions and hair removal using a modified laser device. The specific target for the laser radiation is the melanin within the hair root and within the melanocyte lining of the follicular duct. Pulse width is controlled to provide a direct thermal effect from a single pulse. U.S. Pat. No. 5,647,866 to Zaias discloses a method of hair depilation through the application of pulsed laser energy having a wavelength readily absorbed by hemoglobin. The process of selective photothermoloysis is used by the laser to focus on a particular region in the epidermis to be irradiated. The pulse duration or time period (30 to 40 nanoseconds) is shorter than the thermal relaxation time for melanin in hair. Of recent vintage are U.S. Patent No. 6,045, 548 to Furumoto et al. and U.S. Patent No.

6,168,589 Bl to Tobinick. The '548 Patent is directed to a long pulse alexandrite laser hair removal systems discussed above and operates at approximately 755 nm and has a pulse duration greater than 10 msec. The '589 Patent describes a laser apparatus that emits pulses with a width of Vz to 40 msec, a fiber optic bundle connected to the laser for transmitting the pulses and a sequence control device for controlling the laser to emit the pulses with a time delay between pulses which is less than the thermal relaxation time of the hair being treated. The apparatus also includes a handpiece for directing the laser pulses to a spot on the subject's skin that is to be treated.

Along with the above-described variety of approaches that have been developed to implement the technology for laser hair removal, there has also been a trend towards making laser hair removal systems affordable and portable. Vendors are now preparing to offer extremely lightweight, portable laser hair removal systems. For example, Radiancy advertises its SpaTouch™ PhotoEpilation System on its website claiming that the system combines efficient design and high-yield energy capability to produce a lightweight, tabletop unit with an exceptionally large spot size for speeding treatment time and a single-dial control which makes operating the unit simple. Such systems will move laser hair removal to spas and salons from physician's offices, putting laser hair removal within the reach of the common person.

However, the advent of portable, inexpensive laser hair removal systems ill only come about if they are designed for foolproof safety. Laser light has the potential to cause severe damage to any object that it falls upon, such as clothing. Therefore, hand held lasers or laser hand pieces can cause severe damage if they are accidentally switched on when directed at an unintended target. In fact, this potential for accidental severe damage may well retard the availability of laser hair removal systems at affordable locations such as spas and salons. Therefore, there is a need for a hand held laser system that will fire a laser pulse only when the laser is directed at an intended target. SUMMARY OF THE INVENTION

The present invention satisfies the aforementioned needs by providing a laser hair removal apparatus that is equipped with a protraction-retraction system that provides foolproof safety. The protraction-retraction mechanism is incorporated into the handpiece of a laser hair removal apparatus or into a hand held laser hair removal apparatus. It comprises a laser dispersion tube through which laser pulses travel onto the skin of the subject. The laser dispersion tube is disposed inside a tubular casing with a spring such that when not operational the handpiece or hand held apparatus is in a protracted position, in which position laser pulses are not fired. When the handpiece or hand held apparatus is pushed down onto the skin of the subject, the laser dispersion tube is placed in a retracted position, causing laser pulses to be fired onto the skin of the subject according to a pre-programmed sequence. The invention also provides methods for laser hair removal using the apparatus of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 shows the apparatus of the invention wherein the laser dispersion tube is in a protracted position.

FIGURE 2 shows the apparatus of the invention wherein the laser dispersion tube is in a retracted position.

FIGURE 3 is a schematic block diagram of a laser hair removal apparatus of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is a well-established fact that pulsed laser beams are a concentrated source of energy, which can deliver large amounts of power per unit area (intensity). Thus, when a pulsed laser beam falls on a part of an object, it has the potential to dramatically raise the temperature of that part of the object and thereby cause damage to the object. See, for example, the calculations in Chapter 2 of "Micromanipulation by Light in Biology and Medicine," Karl Otto Greulich, BirkHauser Verlag, Switzerland (1999).

As a consequence laser hair removal systems are provided with a push button-type firing switch for controlling the firing of the laser. However, even with such a switch, there is a potential for accidental damage due to operator error. Thus, for example, the operator may inadvertently depress the switch while the laser is directed at an unintended target, thereby causing the target to suffer damage. Therefore, there is a need for a foolproof laser hair removal system, which the present invention fulfills.

The present invention provides a novel laser hair removal system that is distinguished by a foolproof laser firing system. In particular, the invention provides a handpiece connected to laser hair removal apparatus for delivering laser pulses to a spot on the skin of the subject to be treated or a hand held laser hair removal apparatus that comprises a protraction-retraction mechanism wherein the apparatus fires one or more laser pulses when the apparatus is in a retracted position but does not fire any laser pulses when the apparatus is in a protracted position. Figure 1 shows the handpiece or hand held laser hair removal apparatus 1 in a protracted position. The protraction-retraction mechanism comprises a tubular casing 2 which has casing abutment means 4 along its inner circumference. The tubular casing 2 is disposed around a laser dispersion tube 3 having at one end a laser portal opening 10 and a lens 5 for directing the laser pulses onto a spot on the skin of a subject (not shown). The casing 2 has an opening 13 for receiving a fiber optic bundle 12 from the laser 20. The fiber optic bundle 12 is optically connected to laser dispersion tube 3 such that when the laser 20 is fired laser pulses travel through the fiber optic bundle 12, then through the laser dispersion tube 3 and out through lens 5. The laser dispersion tube 3 is slidably mounted in the casing 2 for movement along the longitudinal axis 11 of the casing 2. Shoulder means 6 extend from the outer circumference of the laser dispersion tube 3. The protraction-retraction mechanism is equipped with a firing switch 14 for firing said laser pulses, which is comprised of two members: a first member 7 attached to the laser dispersion tube 3 and a second member 8 attached to the casing 2. A spring 9 is disposed around the laser dispersion tube 3 and located between the casing abutment means 4 and the shoulder means 6. The spring 9 urges the laser dispersion tube 3 into the protracted position, in which position the first and second members 7 and 8, respectively, of the firing switch 14 are urged away from each other. In operation, when the laser dispersion tube 3 is pushed down onto a spot on the skin 15 of the subject, the spring 9 retracts placing the laser dispersion tube 3 into the retracted position (shown in Figure 2) inside the casing 2, which causes a connection to be made between the first and second members 7 and 8, respectively, of the firing switch 14 turning the firing switch 14 on whereby at least one laser pulse is fired onto the spot on the skin of the subj ect. The protraction retraction mechanism of the present invention can also be used with a pulsed flash lamp, for example, a flash lamp of the type described in U.S. Pat. No. 5,683,380, the entire contents of which are incorporated herein by reference.

In a preferred embodiment, the firing switch 14 is connected to a microprocessor based programmable laser control device 21 which is connected to the laser 20 and controls the laser 20 to fire laser pulses in a pre-programmed sequence when the firing switch is turned on. The laser control device allows the laser energy to be delivered onto the subject's skin in individually adjustable multiple pulses with an adjustable time delay between the pulses. The pulse repetition rate (the delay between pulses) is preferably less than the thermal relaxation time of the hair being treated, and preferably is longer than the thermal relaxation time of the subject's skin. The laser control device can also be used to control the pulse width and fluence of the laser pulses for optimum treatment.

With the laser control device, laser treatment parameters such as laser pulse sequence, fluence and width can be selected for optimal treatment depending on the skin and hair type of the subject being treated. For example, for a Caucasian subject with light brown hair and fair skin, the laser parameters should be selected to allow relatively large delays between pulses (slow pulse repetition rate). The laser parameters to be used for various subject-types are well within the knowledge of a person of ordinary skill in the art. See, for example, United States Patent No. 6,168,589. A laser hair removal apparatus is shown in Figure 3. In this embodiment, the invention provides a laser hair removal apparatus for removing hair follicles from the skin of a subject, which comprises a laser 20 that generates at least one pulse of a pulsed laser beam that travels in a path and is of sufficient energy and pulse duration to damage a hair follicle; an optical delivery means 12 connected to the laser for transmitting the pulsed laser beam; and a handpiece optically connected to the optical delivery means for directing the pulsed laser beam to a spot on the skin of the subject, wherein one or more pulses of the pulsed laser beam are emitted onto the spot on the skin of the subject when the handpiece is pressed down onto said spot. The handpiece is as described above with reference to Figure 1 and includes the afore-mentioned protraction- retraction mechanism. In a preferred embodiment, the apparatus further comprises a laser control device 21 for controlling the laser pulse sequence, fluence and width. Preferably, the control device 21 is microprocessor based and can be programmed, for example, through a computer, to fire pulses in a selected sequence.

In the embodiments described above, the laser 20 and the laser control device 21 are preferably contained in a single housing (not shown). In a hand-held hair laser hair removal device according to the invention, the laser 20, the control device 21, and the optical delivery means 12 and the handpiece 1 are preferably contained in a single housing.

Preferably, the wave length of the pulsed laser beam is from about 500 nm to about 900 nm and most preferably the wave length of the pulsed laser beam is from about 650 nm to about 800 nm. The laser can be one of several lasers used for laser hair removal, for example, an alexandrite laser, a long pulse alexandrite laser, a ruby laser, a diode laser or an infra-red laser.

Depending on the hair and skin-type of the subject being treated, the width of the pulse of the pulsed laser beam is selected to be preferably between about 1 nsec to about 100 msec and most preferably between about 0.5 msec to about 50 msec. Preferably, the fluence of the pulsed laser beam is less than about 100 J/cm2. Preferably, the control device 21 controls the laser to emit pulses of the pulsed laser beam sequentially with a time delay of less than 100 milliseconds between each of the pulses. The control device is preferably in the form of a microprocessor or an electronic timing device.

The optical delivery means include a multi-strand fiber optic bundle for transmitting the pulses of the pulsed laser beam. Alternatively, the optical delivery means include a light path or pipe for transmitting the pulses of the pulsed laser beam.

As would be obvious to one of ordinary skill in the art, the apparatus of the invention can be used in conjunction with the available laser hair removal technologies. For example, the apparatus can be used along with an exogenous absorber. In such an embodiment, a commercially available hair dye solution is first applied to the subject's skin containing the unwanted hair and allowed to migrate along the hair roots and into the follicles. The skin is then irradiated with laser pulses using the apparatus of the invention. Similarly, the apparatus of the invention can be adapted for use with Cynosure's Thermokinetic Selectivity approach.

As is readily apparent, the apparatus of the invention can be used to practice laser hair removal. Thus, the invention also provides a method for laser hair removal using the laser hair removal apparatus for transmitting one or more laser pulses as described above, and which comprises a handpiece that has a protracted position in which the apparatus does not fire the laser pulses and a retracted position in which the apparatus fires laser pulses. According to method of the invention in a first step the handpiece is placed on a spot on the skin of a subject to be treated; and in a second step the handpiece is pushed against the spot on the skin of the subject, causing the handpiece to be placed in a retracted position, which causes one of more laser pulses to be fired onto the spot on the skin of the subject.

All of the foregoing references, which are cited in the body of the instant specification, are hereby incorporated by reference in their entirety.

It is also to be appreciated that the foregoing description of the invention has been presented for purposes of illustration and explanation and is not intended to limit the invention to the precise manner of practice herein. It is to be appreciated therefore, that changes may be made by those skilled in the art without departing from the spirit of the invention and such changes are within the scope of the invention as determined with respect to the following claims.

Claims

WHAT IS CLAIMED IS: 1. A laser hair removal apparatus for damaging hair follicles within the skin of a subject, the apparatus comprising: a housing having a laser that generates at least one pulse of a pulsed laser beam that travels in a path and is of sufficient energy and pulse duration to damage a hair follicle; an optical delivery means connected to said laser for transmitting said pulsed laser beam; and a handpiece optically connected to said optical delivery means for directing said pulsed laser beam to a spot on the skin of said subject, wherein one or more pulses of said pulsed laser beam are emitted onto said spot on the skin of said subject when said handpiece is pressed down onto said spot.

2. The apparatus of claim 1 wherein said handpiece further comprises: a tubular casing having casing abutment means along the inner circumference of said casing; a laser dispersion tube having a laser portal opening and a lens for directing said pulses of said pulsed laser beam onto said spot on the skin of said subject, slidably mounted in said casing for movement along the longitudinal axis of said casing; shoulder means extending from the outer circumference of said laser dispersion tube; a firing switch for firing said laser to emit said pulsed laser beam, said firing switch having a first member attached to said laser dispersion tube and a second member attached to said casing; and a spring disposed around said laser dispersion tube and located between said casing abutment means and said shoulder means, urging said laser dispersion tube into a protracted position whereby said first and second members of said firing switch are urged away from each other; wherein when said laser dispersion tube is pushed down on said spot on the skin of said subject, said spring retracts pushing said laser dispersion tube into a retracted position inside said casing and thereby causing a connection to be made between said first and second members of said firing switch whereby one or more pulses of said pulsed laser beam are fired onto said spot on the skin of said subject.

3. The apparatus of claim 2 wherein the wave length of said pulsed laser beam is from about 500 nm to about 900 nm.

4. The apparatus of claim 2 wherein the wave length of said pulsed laser beam is from about 650 nm to about 800 nm.

5. The apparatus of claim 2 wherein said laser is an alexandrite laser.

6. The apparatus of claim 2 wherein said laser is a long pulse alexandrite laser.

7. The apparatus of claim 2 wherein said laser is a ruby laser.

8. The apparatus of claim 2 wherein said laser is a diode laser.

9. The apparatus of claim 2 wherein said laser is an infra-red laser.

10. The apparatus of claim 2 wherein the width of said pulses of said pulsed laser beam is between about 1 nsec to about 100 msec.

11. The apparatus of claim 2 wherein the width of said pulses of said pulsed laser beam is between about 0.5 msec to about 50 msec.

12. The apparatus of claim 2 wherein the fluence of said pulsed laser beam is less than about 100 J/cm².

13. The apparatus of claim 2 further comprising a laser control device for controlling said laser to emit said pulses of said pulsed laser beam sequentially with a time delay of less than 100 milliseconds between each of said pulses.

14. The apparatus of claim 14 wherein said laser control device is used to control the width, the fluence or the sequence of said laser pulses.

15. The apparatus of claim 13 wherein said laser control device comprises a microprocessor or an electronic timing device.

16. The laser apparatus of claim 2 wherein said optical delivery means includes a multi- strand fiber optic bundle for transmitting said pulses of said pulsed laser beam.

17. The laser apparatus of claim 2 wherein said optical delivery means includes a light path or pipe for transmitting said pulses of said pulsed laser beam.

18. A hand held laser hair removal apparatus comprising a protraction-retraction mechanism wherein said apparatus fires one or more laser pulses when said apparatus is in a retracted position but does not fire any laser pulses when said apparatus is in a protracted position.

19. The hand held laser hair removal apparatus of claim 18 wherein said protraction- retraction mechanism further comprises: a tubular casing having casing abutment means along the inner circumference of said casing; a laser dispersion tube having a laser portal opening and a lens for directing said laser pulses onto a spot on the skin of a subject, slidably mounted in said casing for movement along the longitudinal axis of said casing; shoulder means extending from the outer circumference of said laser dispersion tube; a firing switch for firing said laser pulses, said firing switch having a first member attached to said laser dispersion tube and a second member attached to said casing; and a spring disposed around said laser dispersion tube and located between said casing abutment means and said shoulder means, urging said laser dispersion tube into said protracted position whereby said first and second members of said firing switch are urged away from each other; wherein when said laser dispersion tube is pushed down onto said spot on the skin of said subject, said spring retracts placing said laser dispersion tube into said retracted position inside said casing and thereby causing a connection to be made between said first and second members of said firing switch whereby at least one laser pulse is fired onto said spot on the skin of said subject.

20. A protraction retraction mechanism for use with a laser skin treatment apparatus that emits laser pulses, wherein said protraction-retraction mechanism comprises: a tubular casing having casing abutment means along the inner circumference of said casing; a laser dispersion tube having a laser portal opening and a lens for directing said laser pulses onto a spot on the skin of a subject, slidably mounted in said casing for movement along the longitudinal axis of said casing; shoulder means extending from the outer circumference of said laser dispersion tube; a firing switch for .firing said laser pulses, said firing switch having a first member attached to said laser dispersion tube and a second member attached to said casing; and a spring disposed around said laser dispersion tube and located between said casing abutment means and said shoulder means, urging said laser dispersion tube into a protracted position whereby said first and second members of said firing switch are urged away from each other; . wherein when said laser dispersion tube is pushed down onto a spot on the skin of a subject, said spring retracts placing said laser dispersion tube into a retracted position inside said casing and thereby causing a connection to be made between said first and second members of said firing switch whereby one or more laser pulses are fired by said laser skin treatment apparatus onto said spot on the skin of said subject.

21. A method for laser hair removal using a laser hair removal apparatus that can transmit one or more laser pulses wherein said apparatus comprises a handpiece that has a protracted position in which said apparatus does not fire said laser pulses and a retracted position in which said apparatus fires laser pulses, said method comprising: placing said handpiece on a spot on the skin of a subject to be treated; and pushing said handpiece against said spot on the skin of said subject, causing said handpiece to be placed in the retracted position, whereby one or more laser pulses is fired onto said spot on the skin of said subject.