Surgery – Instruments – Light application
Reexamination Certificate
1998-08-16
2001-08-14
Gibson, Roy (Department: 3739)
Surgery
Instruments
Light application
C607S089000
Reexamination Certificate
active
06273885
ABSTRACT:
FIELD OF THE INVENTION
The invention described is a device and method for photoepilation using a handheld high power semiconductor diode laser based system. The optical energy delivered by the semiconductor laser is absorbed preferentially by melanin in the skin and converted to thermal energy in and around the hair follicles, thus reducing or eliminating their ability to produce hair.
BACKGROUND OF THE INVENTION
Laser based photoepilation has been the object of study since the advent of the laser. It has been know for several years that optical pulses of the appropriate wavelength, pulse duration, and energy density impinging upon human skin will result in significant and enduring hair loss. The accepted theory for this phenomenon is that the penetration of the laser into the skin and its subsequent scattering results in heating of the hair shafts and follicles through selective absorption by melanin. The absorption of the radiation leads to heating of the follicle and subsequent thermal necrosis.
It has been found that for effective photoepilation to occur the energy must be penetrate approximately 3 mm into the tissue. Prevailing thought indicates that this means the absorption should occur in the melanin and not the oxyhemoglobin, thereby heating the regions around the hair follicle instead of heating the blood and blood vessels. Energy absorption in the melanin leads to elimination of the hair and the reduction or elimination of the ability of follicle to produce hair. Based on the absorption spectrum of melanin and oxyhemoglobin the wavelengths in the neighborhood of 700 nm have been thought to be efficacious. Therefore the Ruby laser at 694 nm, the Alexandrite laser around 760 nm, and flashlamps with emission spectrum centered near 700 nm have been used for this application. The aforementioned lasers are very inefficient, requiring high voltages, large supplies of cooling water. In addition, delivery of the energy to the skin surface is problematic due to the energy required for photoepilation. The pulse energies often exceed damage thresholds of delivery systems or are difficult channel to from the laser to the skin. The flashlamps themselves are inefficient, emit in all directions making efficient energy delivery difficult, and the flashlamps can be cumbersome to use in a handheld device. The convenient and controlled delivery of the optical energy of the appropriate wavelength, fluence and pulse duration to the skin surface for photoepilation in an efficient device has been difficult.
ADVANTAGES AND SUMMARY OF THE INVENTION
The epilation process is dependent on 3 basic parameters: wavelength, total mount of energy deposited or delivered, and pulsewidth. High power semiconductor diodes are the only devices that allow the flexibility change all three parameters in the optical pulses as the situation requires. Current lasers (e.g. Ruby and Alexandrite ) are limited in their ability to deliver the energy in the optimal time period. In addition, their small size allows them to be placed in a handheld unit allowing for ease of patient treatment. Finally, their lifetimes are significantly longer than flashlamp based laser systems currently in use.
The prior art displaced by a handheld semiconductor diode device is the flashlamp pumped Ruby laser, the flashlamp pumped Alexandrite laser and handheld flashlamp systems. All of the aforementioned systems suffer from the fact that they require high voltage in order to drive the flashlamps which have a lifetime considerably less than that of the diode laser. In addition, the diode laser arrays are much smaller than flashlamps, making a handheld device easier to use and position on the area to be treated.
Thus, it is an advantage of the present invention to provide a handheld, semiconductor diode laser or diode array device, optionally having an active or passive heat sink or thermal conduction plate for maintaining the surface temperature of the skin from overheating, for photoepilation and other dermatological applications.
It is a further advantage of the present invention to provide a semiconductor diode laser or diode array having a microlens or microlenses for shaping, confluencing, or otherwise optically modifying. the laser produced by the diode laser, diodes or diode array.
It another advantage of the present invention to provide such a handheld photoepilation system which requires lower voltage than conventional flashlamp pumped ruby or alexandrite or other type lasers.
The described invention provides an improved laser system for performing treatment of skin, including but not limited to photoepilation. One embodiment of the improved laser system is a handheld device comprising a semiconductor diode laser and chilled plate that transmits the laser energy to the skin. The transparent chilled plate is used in order to keep the temperature of the epidermis low enough to avoid significant thermally induced damage.
The semiconductor diode laser comprises a diode array or a single element device produces a fluence level of approximately 20-40J/cm
2
. The semiconductor laser would be typically operated in a pulsed mode with pulsewidths between approximately 1 millisecond and where the wavelength of the semiconductor diode laser is between approximately 630 nm and 980 nm.
Additionally, the semiconductor diode laser energy can be collimated using a micro-lens array or other focusing elements in order to obtain the appropriate fluence. In another embodiment, the collimated semiconductor diode laser energy is reflected off of a polarizer or dichroic plate so that the user can observe the region of skin while the diode laser energy is impinging upon the skin.
Another embodiment of the handheld device is a system where the energy is transmitted to the handpiece using one or more optical fibers. The handpiece includes the optical fiber(s) and, optionally, a set of lenses used to collimate the energy transmitted through a chilled transparent plate.
The device described here is a handheld, diode laser based system for delivering optical pulses. An optimal wavelength for epilation is approximately 700 nm since the oxyhemoglobin absorption is a minimum here while absorption by the melanin is still significant. Currently standard high power diodes are available from roughly 780 nm to 870 nm, and the present device uses high power diode arrays, optionally micro-lensed high power diode arrays, which produce wavelengths in the range from 780 nm to 830 nm.
The energy would be delivered in a spot size of approximately about 1 cm
2
. The energy would be delivered in less than 1 second, and typically in less than 50 milliseconds, with a peak power of approximately 1 Kw. One embodiment of the device would utilize a transparent plate that is cooled in conjunction with the high power diodes. The purpose of the chilled transparent plate is to allow the diode energy through while simultaneously reducing the temperature of the epidermis thereby reducing heat induced damage to the epidermis.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.
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Johnston Timothy J.
Koop Dale E.
Selker Mark D.
CoolTouch Corporation
Gibson Roy
Shahani, Esq. Ray K.
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