Note: Descriptions are shown in the official language in which they were submitted.
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De3cription
"METHOD AND APPARATIJS FOR LASER DEPILATION"
Technical Field
This invention relates to a method and apparatus for
devitalization of human hair through use of a high energy, short
duration, light pulse of a wavelength that passes through the
skin of the patient without substantial absorption and is
absorbed in the hair root.
Background Art
Relatively permanent removal of aesthetically un-
desirable body hair is generally performed on a clinical basis
using electrolysis techniques. These techniques involve some
pain, are time consuming, and demand a fair degree of expertise
in their application.
As an alternative, it has been proposed to employ high
energy light pulses to heat and thereby devitalize the blood
circulation system which feeds the hair roots. U.S. Patent
; 3,693,623 discloses a technique in which a high energy light
pulse is derived from a Xenon arc source and passed through a
glass fiber conduit to a manually supported pro~e terminating in
an elongated single glass fiber needle adapted to be extended
into a haix follicle, alongside the hair body. The high energy
light pulse from the Xenon arc source is then passed through the
conauit tocause photo-coagulation of ~ody tissue surrounding
the follicle, devitalizing the hair.
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U.S. Patent 3,834,391 suggests a number of disadvan-
tages of the photo-coagulation method involving insertion of a
fine optical fiber into the hair follicle and discloses an alter-
native method wherein the light pulse from the Xenon lamp is
positioned ". . . to the exterior of and touching the entrance
of a follicle containing a living hair shaft and root . . ." so
that the light energy is transmitted through the oils contained
with the follicle to heat the ~ody tissues adjacent to the hair
root to devitalize the hair. The latter patent proposes rubbing
mineral oil into the epidermis in the vicinity of the follicle
prior to applying the light pulse in order to assure the proper
transmission of the light through the follicle.
This latter method involves extremely accurate position-
ing of the manually supported probe and depends upon the highly
variable thermal conductivity of the hair follicle to achieve
the goal.
; Disclosure of the Invention
The present invention relates to an improved method of
photo-depilation and to apparatus for practicing the method which
relieves the operator of the difficult task of manually position-
ing the probe with a high degree of precision, is substantially
painless to the patient and devitalizes a higher percentage of
body hairs operated upon than the previous method.
Broadly, the method of the present invention involves
generating a focused, collimated pulse of light at a point on the
; epidermis of the patient closely separated from the exit point of
the hair body and at an angle to the epidermis surface aimed at
the hair root. The light pulse is of such a wavelength that
there is very little absorption of the light within the epidermis
and dermis of the patient but most of the light is absorbed within
the hair root, causing heating of the hair root and coagulation
of the tiny arteries which sustain life within the root. The
method works best with relatively light skinned, dark haired
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patients--i.e., brunette Causasions, whose body hair is the most
visually apparent, but also works with varying degrees of efficacy
with lighter haired and darker skinned patients. The ~avelength
of the light used is preferably in the vicinity of 5,000 angstroms
and is preferably derived from an argon laser.
The use of a focused beam projecting from the end of
a probe allows the probe to be supported a short distance away
from the hair body, such as 1/2 to 3/4 of an inch, so the operator
has a clear field of vision as to the position of the probe and
the beam relative to the hair and its root. The burden on the
operator is further relieved through use of a novel apparatus
which supports the probe end and allows it to be easily positioned
within a two-axis coordinate system. The preferred embodiment
of the positioning system includes a pair of pulse motors which
drive the probe along two perpendicular coordinate axes. A
manually controlled joy stick controls the generation of pulses
that are provided to the two motors. The pulses for the two
axes are generated as a function of the displacement and direction
of displacement of the joy stick from its neutral position. Mov-
20 ing the joy stick in one direction provides pulses for one ofthe motors at a rate proportional to the displacement of the joy
stick. Motion of the joy stick at 90 to that direction controls
the other motor. Motions of the joy stick at intermediate angles
produce motions which are functions of the x and y components of
the joy stick motion.
In the practice of the method, the patient lies on a
table and the probe support is adjusted so that the probe end
is closely spaced above the area of the patient's skin to be
operated upon. The motor driven control system is then used to
accurately position the probe.
The optical system includes an attenuator normally
positioned in the laser beam path so that the output beam is
greatly reduced in intensity and enlarged in diameter and may be
used to position the probe. When the desired probe position is
; 35 achieved the attenuator is removed from the optical path for the
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desired pulse time, allowing passage of the full high energy
pulse which produces the desired photo-coagulation. The pulses
may be repeated until the hair body is easily removed from the
follicle.
Other objectives, advantages and applications of the
present invention will be made apparent by the following detailed
description of the preferred embodiment of the method and appar-
atus.
Brie~ Description of the Drawings
The description makes reference to the accompanying
drawings in which:
FIGURE 1 is a schematic view illustrating the beam
output end of the optical system positioned above the skin of a
patient in accordance with the inventive method to transmit
thermal energy to the hair root to devitalize it, with the adja-
cent skin section o~ the patient shown in cross-section;
FIGURE 2 is a perspective view of the apparatus of
the present method being used to remove facial hair;
FIGURE 3 is a side view of the apparatus of the pre-
sent invention; and
FIGURE 4 is a schematic view of the beam attenuator.
Detailed Description
A cross-section through a hair body 10 and the surround-
~ ing sk.in section is illustrated in FIGURE 1. The hair body 10
; 25 is supported in a hair follicle or passage 12 formed through the
surface epidermis 14 of the patient and the underlying dermis 16.
At its lower end th.e hair body terminates in a root section 18
nouri.shed by a network of small blood vessels 20. In order to
remove the hair in such a manner as to prevent recurrent growth
it i.s. necessary to devitalize. the root section 18 as by coagulat-
ing the vessels 20. to prevent nourishment of the root 18. In
the practice of the present invention an intense collimated beam
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of light 22 is aimed at a point on the epidermis of the patient
spaced from the exit point of the hair follicle through the
epidermis, and at such an angle with respect to the epidermis
so that a continuation of the beam intersects the hair root 20.
The beam will preferably have an actual strength of
1/2 to 2-l/2 watts and may be derived from a laser having a
maximum power of approximately 3 watts.
The beam will necessarily be projected for a rela-
tively short duration; i.e., less than about 0.40 seconds, and
preferably more than 0.01 seconds, depending in art upon the
beam strength.
The beam will preferably be derived from an argon
laser and will have most of its energy in the wavelength of
approximately 4,800 to 5,200 anstroms. Light of this wavelength
passes through relatively light human skin without any appreciable
absorption yet is highly absorbed in a dark hair root. The
thermal energy produced upon absorption of the light energy
within the hair root 18 causes coagulation of the blood vessels
22 and destroys the hair root. The hair body is generally
vaporized in this process. It may be necessary to apply multiple
; pulses to allow complete devitalization. This process is
relatively painless to the patient because of the low degree
of absorbency and short pulse within the dermis 16.
In order to allow careful aiming of the probe relative
to the hair body before the power beam is applied, a light beam
having only a small fraction of the power of the devitalizing
beam is preferably employed. Such a lower power beam may be
generated by blocking the major portion of the optical path from
the laser by an attenuator in a manner which will be subsequently
described. Since this aiming beam is derived from the same
source and uses the same optical path as the devitalizing beam,
it allows accurate positioning of the probe.
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In FIGURE 1, the probe, generally indicated at 24,
comprises an elongated tube 26 supporting the output end of a
flexible optical fiber bundle 28. A plano-convex lens 30 is
positioned in the tube 26 with its convex surface in opposition
to the end of the fiber optic bundle 28. The lens 30 collimates
a beam o~ light emerging from the bundle 28 at a point a few
millimeters beyond the tube end 32. Therefore the probe 24
may be positioned with its end a short distance above the skin
of the patient to allow a clear field of view for aiming the
laser.
A preferred embodiment of apparatus for practicing
the method of the present invention is illustrated in FIGURES 2
and 3. The apparatus broadly consists of a laser 34 supported
within a wheeled table 36; an examination table, generally
indicated at 38 on ~hich a patient 40 may lie; and a position1ng
system 42 which supports and adjusts the probe end 24 of the
optical s~stem with respect to the examination table. In the
preferred embodiment of the invention the laser 34, its support-
ing table 36, the optical fiber cable 28 and the probe 24, in-
cluding the shutter system, may be of the type made commercially
available as the "System 1000 Argon Surgical Laser" by Coherent
Radiation, Inc., Medical Division, of Palo Alto, California.
This form of surgical laser is marketed for use by dermatologists
and the like for use in removal of cutaneous anomalies. This
system produces both the aiming and power beams required for the
practice of the present invention when a 3-watt argon laser is
provided with the system.
In the apparatus of the present invention the output
probe 26 is supported in a friction ball joint 44 so that the
3Q angle of the probe relative to the support may be manually ad-
justed. The ball joint is fixed at the end of a support plate
48 retained in an x-y positioning system arrayed parallel to
the surface of table 38. The positioning system is controlled
by a pair of stepping motors 50 and 52. Drive signals for the
stepping motors are generated under control of a manually
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adjustable joy stick 54 which projects from a control box 56
supported on top of the examination table.
The joy stick is spring biased into an upright vertical
position. It may be manually moved against the bias in any
d;rection. A commercially available system (not illustrated)
generates two electrical signals having frequencies proportional
to the components of the displacement of the joy stick from its
neutral position, along two perpendicular axes. For example, if
the joy stick is moved in a forward direction, away from the
operator, pulses will only be provided by one of the generators,
at a frequency proportional to the displacement of the joy stick
from its neutral position. A movement at 90 to the first dir-
ection will pro~uce pulses from the other generator and inter-
mediate positions will produce pulses from both generators
proportional to the components of that displacement along the
two axes. The generators produce pulses of an opposite sign
when the joy stick is moved in a reverse direction.
These pulses are provided to the stepping motors 50
and 52 to cause them to move the support plate 48 and the probe
44 in a direction and a rate proportional to the joy stick dis-
placement.
The positioning system is supported on a beam 58
which projects horizontally over the top of the examination table
38. The horizontal beam 58 is supported in a vertically extend-
ing beam 60 and the horizontal extension of the beam 58 and itsangle of extension may be manually adjusted employing a locking
mechanism 62. Similarly, the vertical beam 60 is retained in a
clamping system 64 affixed to the rear of the examination table
38. Manually adjustable clamps 66 may be used to adjust the
vextical extensian of the heam 60 with respect to the table.
A faot pedal 68 connected to the laser support table
36 by cable 7Q, allows opexator s~itching between the attenuated,
low power aiming beam and the high power depilation beam. FIGURE
4 illustrates in schematic ~orm the manner of attenuating the
beam. The cable 70 connects to a control box 72 which in turn
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connects to a solenoid 74. A shutter 76 is energized by the
solenoid 74. The shutter is disposed in the optical path of
the laser beam before it reaches the fiber optic cable 28. The
solenoid 74 is supported on a tube 78 through which the laser
beam passes. When the shutter 76 is extended it blocks the
major portion o~ the laser beam, allowing only a small percen-
tage of the laser light, such as about 5%, to pass into the
fiber optic cable 28. This produces the low power aiming beam.
When the foot pedal 68 is depressed, the control 72 sends a short
timed pulse, having a period independent of the period of de-
pression of the foot pedal 68, to the solenoid 74, withdrawing
the shutter for the period of the required depilating pulse.
The shutter 76 is spring biased toward its closed position so
that it will retain this position in event of failure of the
solenoid 74.
In operation, a patient 40 lies on the examination
table 38 and the probe and its support are manually positioned
over the skin area of the patient to be operated upon, ~y adjust-
ment of the horizontal beam 58 and the vertical beam 60. The
angle of the probe 26 with respect to the support is also ad-
justed by manipulation of the ball joint 44. The laser is then
energized to produce the low power aiming beam. The operator
visually positions the probe 24 with respect to a hair root in
the manner illustrated in FIGURE l and then depresses the foot
pedal 68, producing the power beam for the required period. The
beam passes substantially -transparently through the dermis and
epidermis of the patient and is absorbed in the hair root 18,
causing coagulation of the feeder vessels 20. The hair may then
be manually removed by pulling on it.
The control system of the laser includes means for
adjusting the output power of the laser and the duration of the
beam fox adjustment to individual patients.
