U.S. patent application number 12/191163 was filed with the patent office on 2009-02-26 for multiple wavelength laser workstation.
This patent application is currently assigned to CYNOSURE, INC.. Invention is credited to James Henry Boll, Joseph M. Day, Eric Calvin Koschmann, Evan Andrew Sherr, Rafael Armando SIERRA.
Application Number | 20090054956 12/191163 |
Document ID | / |
Family ID | 36384531 |
Filed Date | 2009-02-26 |
United States Patent
Application |
20090054956 |
Kind Code |
A1 |
SIERRA; Rafael Armando ; et
al. |
February 26, 2009 |
MULTIPLE WAVELENGTH LASER WORKSTATION
Abstract
Lasers capable of lasing at least two wavelengths are provided
having a lasing medium which is capable of lasing at a first
wavelength and at a second wavelength. An output coupler is
positioned along a longitudinal axis at a first end of the lasing
medium and a first mirror, movable beam block shutter and second
mirror are positioned sequentially along the longitudinal axis of
the lasing medium at a second end of the lasing medium. The first
mirror is highly reflective at a first wavelength, and the second
mirror is highly reflective at a second wavelength while being
transparent at the first wavelength. The beam block shutter is
movable between a first position along the longitudinal axis of the
lasing medium and between the first and second mirrors and a second
position away from the longitudinal axis of the lasing medium. Also
provided are laser workstations having two lasers driven by a
single electronics drive system in which a single energy storage
network is connected to a first laser pump chamber operative to
excite a first laser medium and connected to a second laser pump
chamber operative to excite a second laser medium. In certain
embodiments, a switch connects the single energy storage network to
a secondary winding of a high voltage trigger transformer, which is
itself connected to the laser pump chambers. These high voltage
trigger transformer serve to selectively ionize the excitation
source in one of the laser pump chambers such that when the switch
is closed, energy from the energy storage network will flow through
the pump chamber whose excitation source(s) has been previously
ionized. In other embodiments, the single energy storage network is
connected to the excitation sources via active semiconductor
switches that permit the release of portions of energy stored in
the single energy storage network to one of the lasers, leaving
additional energy to be immediately or rapidly released to the
excitation source of the first or another laser. Also provided are
methods of treating skin having a skin problem using multiple
wavelengths of laser energy.
Inventors: |
SIERRA; Rafael Armando;
(Palmer, MA) ; Koschmann; Eric Calvin; (Hudson,
NH) ; Day; Joseph M.; (Warren, MA) ; Sherr;
Evan Andrew; (Ashland, MA) ; Boll; James Henry;
(Newton, MA) |
Correspondence
Address: |
FOLEY & LARDNER LLP
111 HUNTINGTON AVENUE, 26TH FLOOR
BOSTON
MA
02199-7610
US
|
Assignee: |
CYNOSURE, INC.
|
Family ID: |
36384531 |
Appl. No.: |
12/191163 |
Filed: |
August 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11035680 |
Jan 14, 2005 |
7427289 |
|
|
12191163 |
|
|
|
|
Current U.S.
Class: |
607/89 ;
372/41 |
Current CPC
Class: |
H01S 3/061 20130101;
A61B 2018/00452 20130101; H01S 3/092 20130101; H01S 3/1611
20130101; H01S 3/2383 20130101; A61B 18/203 20130101; H01S 3/082
20130101; A61N 5/0616 20130101; A61B 2018/207 20130101; H01S
3/08086 20130101; H01S 3/1643 20130101 |
Class at
Publication: |
607/89 ;
372/41 |
International
Class: |
A61N 5/06 20060101
A61N005/06; H01S 3/16 20060101 H01S003/16 |
Claims
1. A laser device comprising: a lasing medium capable of lasing at
a first wavelength and a second wavelength, the lasing medium
having a longitudinal axis; an output coupler located at a first
end of the lasing medium along the longitudinal axis of the lasing
medium; a first mirror located at a second end of the lasing medium
along the longitudinal axis of the lasing medium, the first mirror
being highly reflective at the first wavelength; a second mirror
located between the first mirror and the second end of the lasing
medium along the longitudinal axis of the lasing medium, the second
mirror being highly reflective at the second wavelength and
transparent at the first wavelength; and a beam block shutter
movable from a first position along a longitudinal axis of the
lasing medium between the first and second mirrors along the
longitudinal axis of the lasing medium to a second position away
from the longitudinal axis of the lasing medium.
2. The laser of claim 1, wherein the lasing medium is a crystal
rod.
3. The laser of claim 1, wherein the lasing medium is one of an
Nd:YAG crystal and a YAP:Nd crystal.
4. The laser of claim 1, wherein the lasing medium is an Nd:YAG
crystal, the first wavelength is 1064 nm and the second wavelength
is 1320 nm.
5. A laser workstation comprising a first laser and a second laser,
wherein the first laser and the second laser are driven by a single
electronics drive system comprising a single energy storage network
connected to a first laser pump chamber and connected to a second
laser pump chamber, wherein the first laser pump chamber is
operative to excite a first laser medium and the second laser pump
chamber is operative to excite a second laser medium.
6. The laser workstation of claim 5, further comprising a switch
located between the single energy storage network and the first
laser pump chamber and second laser pump chamber.
7. The laser workstation of claim 6, wherein the first laser pump
chamber is connected to the single energy storage network by a
first high voltage trigger transformer and wherein the second laser
pump chamber is connected to the single energy storage network by a
second high voltage trigger transformer.
8. The laser workstation of claim 7, wherein the first high voltage
trigger transformer is operative to ionize a first lamp in the
first laser pump chamber when the switch is open.
9. The laser workstation of claim 7, wherein the second high
voltage trigger transformer is operative to ionize a second lamp in
the second laser pump chamber when the switch is open.
10. The laser workstation of claim 5, wherein the first laser is a
pulse dye laser.
11. The laser workstation of claim 10, wherein the pulse dye laser
has an output of between about 575 nm and about 650 nm.
12. The laser workstation of claim 5, wherein the second laser is
an Nd:YAG laser.
13. The laser workstation of claim 12, wherein the Nd:YAG laser
comprises: an Nd:YAG lasing medium having a longitudinal axis; an
output coupler located at a first end of the Nd:YAG lasing medium
along the longitudinal axis of the Nd:YAG lasing medium; a first
mirror located at a second end of the Nd:YAG lasing medium along
the longitudinal axis of the Nd:YAG lasing medium, the first mirror
being highly reflective at 1064 nm; a second mirror located between
the first mirror and the second end of the Nd:YAG lasing medium
along the longitudinal axis of the Nd:YAG lasing medium, the second
mirror being highly reflective at 1320 nm and transparent at 1064
nm; and a beam block shutter movable from a first position along a
longitudinal axis of the Nd:YAG lasing medium between the first and
second mirrors along the longitudinal axis of the Nd:YAG lasing
medium to a second position away from the longitudinal axis of the
Nd:YAG lasing medium.
14. The laser workstation of claim 13, wherein the Nd:YAG lasing
medium is a crystal rod.
15. The laser workstation of claim 13, wherein the second mirror is
coated with a coating that is antireflective at 1064 nm.
16. The laser workstation of claim 5, further comprising a
handpiece connected critically to the first laser and second
laser.
17. The laser workstation of claim 16, wherein the handpiece
comprises a plurality of lenses operative to focus the laser
radiation.
18. The laser workstation of claim 16, wherein the handpiece is
connected to the first laser and second laser by an optical
fiber.
19. The laser workstation of claim 15, wherein the handpiece is
connected to the first laser and second laser by a wave guide.
20. The laser workstation of claim 5, wherein the single energy
storage network is operably connected to the first laser pump
chamber by an active semiconductor switch and to the second laser
pump chamber by an active semiconductor switch.
21. The laser workstation of claim 20, wherein the active
semiconductor switches each are selected from the group consisting
of an insulated gate bipolar transistor and a field effect
transistor.
22. The laser workstation of claim 20, wherein the active
semiconductor switch is an IGBT.
23. The laser workstation of claim 20, wherein the first laser
device comprises a pulse dye laser.
24. The laser workstation of claim 20, wherein the first laser
device comprises an Alexandrite laser.
25. The laser workstation of claim 24, wherein the Alexandrite
laser is a variable pulse 755 nm Alexandrite laser.
26. The laser workstation of claim 20, wherein the second laser
device comprises: a second lasing medium capable of lasing at a
first wavelength and a second wavelength, the lasing medium having
a longitudinal axis; an output coupler located at a first end of
the lasing medium along the longitudinal axis of the lasing medium;
a first mirror located at a second end of the lasing medium along
the longitudinal axis of the lasing medium, the first mirror being
highly reflective at the first wavelength; a second mirror located
between the first mirror and the second end of the lasing medium
along the longitudinal axis of the lasing medium, the second mirror
being highly reflective at the second wavelength and transparent at
the first wavelength; and a beam block shutter movable from a first
position along a longitudinal axis of the lasing medium between the
first and second mirrors along the longitudinal axis of the lasing
medium to a second position away from the longitudinal axis of the
lasing medium.
27. The laser workstation of claim 26, wherein the second laser
device comprises an Nd:YAG laser.
28. The laser workstation of claim 27, wherein the first mirror is
highly reflective at 1064 nm and the second mirror is highly
reflective at 1320 nm and transparent at 1064 nm.
29. A method of treating a skin problem comprising the steps of:
providing a laser device comprising; a lasing medium capable of
lasing at a first wavelength and a second wavelength, the lasing
medium having a longitudinal axis; an output coupler located at a
first end of the lasing medium along the longitudinal axis of the
lasing medium; a first mirror located at a second end of the lasing
medium along the longitudinal axis of the lasing medium, the first
mirror being highly reflective at the first wavelength; a second
mirror located between the first mirror and the second end of the
lasing medium along the longitudinal axis of the lasing medium, the
second mirror being highly reflective at the second wavelength and
transparent at the first wavelength; and a beam block shutter
movable from a first position along a longitudinal axis of the
lasing medium between the first and second mirrors along the
longitudinal axis of the lasing medium to a second position away
from the longitudinal axis of the lasing medium; and treating an
area of skin affected by a skin problem by using the laser device
to apply laser energy at the first wavelength to the area of skin
affected by a skin problem and using the laser device to apply
laser energy at the second wavelength to the area of skin affected
by the skin problem.
30. A method of treating a skin problem comprising the steps of:
providing a laser device comprising a laser workstation comprising
a first laser and a second laser, wherein the first laser and the
second laser are driven by a single electronics drive system
comprising a single energy storage network connected to a first
laser pump chamber and connected to a second laser pump chamber,
wherein the first laser pump chamber is operative to excite a first
laser medium and the second laser pump chamber is operative to
excite a second laser medium; and treating an area of skin affected
by a skin problem by using the laser device to apply laser energy
from the first laser at a first wavelength to the area of skin
affected by a skin problem and using the laser device to apply
laser energy from the second laser at a second wavelength to the
area of skin affected by the skin problem.
31. The method of claim 30, wherein the laser energy from the first
laser is at a different wavelength from the laser energy from the
second laser.
32. The method of claim 30, wherein the laser energy from the first
laser and the laser energy from the second laser are applied
simultaneously.
33. The method of claim 30, wherein the laser energy from the first
laser is applied sequentially with energy from the second
laser.
34. The method of claim 33, wherein the laser energy from the first
laser and the laser energy from the second laser are each applied
in sub-pulses.
35. The method of claim 34, wherein sub-pulses from the first laser
are intercalated with sub-pulses from the second laser.
36. The method of claim 34, where a pulse train of sub-pulses from
the first laser are followed by a sub-pulse from the second
laser.
37. The method of claim 31, wherein the first laser comprises a
pulse dye laser and the second laser comprises: an Nd:YAG laser
having a longitudinal axis; an output coupler located at a first
end of the Nd:YAG laser along the longitudinal axis of the Nd:YAG
laser; a first mirror located at a second end of the Nd:YAG laser
along the longitudinal axis of the Nd:YAG laser, the first mirror
being highly reflective at the 1064 nm; a second mirror located
between the first mirror and the second end of the Nd:YAG laser
along the longitudinal axis of the Nd:YAG laser, the second mirror
being highly reflective at 1320 nm and transparent at 1064 nm; and
a beam block shutter movable from a first position along a
longitudinal axis of the Nd:YAG laser between the first and second
mirrors along the longitudinal axis of the Nd:YAG laser to a second
position away from the longitudinal axis of the Nd:YAG laser.
38. The method of claim 37, wherein the first wavelength is 595 nm
and the second wavelength is 1064 nm.
39. The method of claim 37, wherein the skin problem is leg or
facial veins.
40. The method of claim 37, wherein the first wavelength is 595 nm
and the second wavelength is 1320 nm.
41. The method of claim 40, wherein the skin problem is acne, acne
scarring, scarring, sun-damaged skin, or wrinkled skin.
42. A method of treating a vascular legion comprising the steps of:
providing a laser device comprising a laser workstation comprising
a first laser and a second laser, wherein the first laser and the
second laser are driven by a single electronics drive system
comprising a single energy storage network connected to a first
laser pump chamber and connected to a second laser pump chamber,
wherein the first laser pump chamber is operative to excite a first
laser medium and the second laser pump chamber is operative to
excite a second laser medium; and treating a vascular legion by
using the laser device to apply laser energy at 595 nm from the
first laser to the vascular legion and using the laser device to
apply laser energy at 1064 nm from the second laser to the vascular
legion.
43. The method of claim 42, wherein the first laser is a pulse dye
laser and the second laser is a solid-state laser.
44. The method of claim 43, wherein the second laser is an Nd:YAG
laser.
Description
FIELD OF THE INVENTION
[0001] The invention relates to the field of lasers, particularly
to lasers utilized in the treatment of skin and skin
conditions.
BACKGROUND OF THE INVENTION
[0002] The use of electromagnetic radiation in the visible and
infrared regions of the spectrum has become commonplace in many
areas of industry, medicine and research. For example, such
radiation is of growing importance in the field of dermatology. In
many cases, laser sources are used to generate the desired
radiation level at the needed wavelength.
[0003] There are a myriad of lasers that are commonly used for
dermatological applications such as treatment of vascular lesions
or pigmented lesions, hair removal and skin resurfacing. The
principle of selective photothermolysis underlies many laser
therapies and is used to treat such diverse conditions such as
varicose veins, portwine stain birthmarks, other ecstatic vascular
lesions, and pigmented lesions including tattoos. The dermal and
epidermal layers containing the targeted structures are irradiated
with light, usually from lasers or flashlamps. The wavelength of
this light is chosen so that its energy will be preferentially or
selectively absorbed in the structures. This creates localized
heating with the intent of raising the temperature to a point at
which constituent proteins will denature or pigment particles will
disperse.
[0004] Recently, the treatment of aged skin has become an important
aspect of cosmetic dermatology. This treatment, often referred to
as "skin rejuvenation," includes elements of many of the commonly
performed treatments. The goal of skin rejuvenation is to improve
the appearance of aged skin by, for example, improving skin
pigmentation, removing facial vessels, reducing wrinkles and fine
lines, and improving skin elasticity and texture. Although numerous
single-laser techniques have been proposed, there is a growing
consensus that skin rejuvenation is best addressed by using
multiple laser modalities. It follows that a single laser
workstation that provides multiple lasers to address all of the
components of skin rejuvenation would be desirable.
[0005] Presently, there are three lasers that have been shown to be
particularly useful in the treatment of aged skin. These are the
pulse dye laser (PDL), operating at a wavelength in the range of
585-600 nm; the Nd:YAG laser operating at 1064 nm; and the Nd:YAG
laser operating at 1320 nm. The PDL improves pigmentation, can
treat small facial vessels and promotes collagen stimulation. The
results, particularly on fine lines and wrinkles, however, are
often only subtle. The 1064 nm Nd:YAG laser can treat larger
vessels and stimulate collagen, but does not have an acceptable
effect on pigmentation. Finally, the 1320 nm Nd:YAG laser improves
skin elasticity and reduces wrinkles and fine lines.
[0006] Generally, dermatological treatments utilizing multiple
wavelengths involve separate laser systems having separate controls
and separate delivery devices. An exposure is made using one laser,
and subsequently the same area is exposed with a second laser. With
such a method, the timing between the laser pulses is difficult to
control exactly, and the time between pulses is usually seconds,
rather than fractions of a second. Such timing problems may affect
the clinical outcome.
[0007] A work station that included all three of these lasers would
allow the practitioner to achieve optimal results in all aspects of
treatment. Such a work station that merely packaged one of each of
these lasers together would not be commercially attractive,
however, as it would offer little to no cost advantage over three
individual lasers.
[0008] It is an object of the present invention to provide a laser
workstation that reduces or wholly overcomes some or all of the
difficulties inherent in prior known devices. It is a further
object of the invention to provide a laser workstation that
provides laser output at 585-600 nm, 1064 nm and 1320 nm.
Particular objects and advantages of the invention will be apparent
to those skilled in the art, that is, those who are knowledgeable
or experienced in this field of technology, in view of the
following disclosure of the invention and detailed description of
certain preferred embodiments.
SUMMARY
[0009] In accordance with a first aspect, lasers capable of lasing
at least two wavelengths are provided. The laser has a lasing
medium which is capable of lasing at a first wavelength and at a
second wavelength. In certain embodiments, the lasing medium is
capable of lasing at the first and second wavelengths each to a
sufficient degree to produce laser output of sufficient power for
the intended purpose(s) to which the laser is being applied. The
lasing medium has a longitudinal axis, along which an output
coupler resides at a first end of the lasing medium. At a second
end of the lasing medium, a first mirror and a second mirror are
located along the longitudinal axis, the second mirror being
located between the first mirror and the lasing medium. The first
mirror is highly reflective at a first wavelength, and the second
mirror is highly reflective at a second wavelength while being
transparent at the first wavelength. A beam block shutter is
arranged to be movable between a first position along the
longitudinal axis of the lasing medium and between the first and
second mirrors and a second position away from the longitudinal
axis of the lasing medium.
[0010] Under operation, the second mirror reflects radiation at the
second wavelength while allowing radiation at the first wavelength
to pass through it. When the beam block shutter is in the first
position, along the light path of the lasing medium, the beam block
shutter prohibits radiation that passes through the second mirror
from reaching the first mirror and being reflected back into the
lasing medium. Thus, only radiation at the second wavelength is
reflected, amplified and ultimately emitted. When the beam block
shutter is in the second position, out of the longitudinal axis of
the lasing medium and thus out of the light path, radiation at the
first wavelength passes through the second mirror to the first
mirror and is reflected back into the lasing medium.
Simultaneously, radiation at the second wavelength is reflected
back into the lasing medium. The output coupler is selected to
permit the emittance of radiation at either or both of the first
and second wavelengths. Such an arrangement advantageously permits
the laser resonator to have all of the critical optical components
(the lasing medium, the mirrors and the output coupler) mounted in
a stationary fashion rather than requiring a tuning element or
switching of mirrors, resulting in a robust and relatively
maintenance-free workstation, capable of emitting two wavelengths
from a single lasing medium.
[0011] In accordance with a second aspect, laser workstations are
provided having two lasers and a single electronics drive system.
The single energy drive system is operatively connected by a switch
to a first laser pump chamber that excites a first lasing medium
and to a second laser pump chamber that excites a second lasing
medium. In certain embodiments, the laser pump chambers are each
connected to the single energy storage network by high voltage
trigger transformers, secondary windings of which are in series
with excitation sources within the pump chambers, for example,
lamps such as flashlamps, and thus are inductors in the excitation
source discharge circuits. These high voltage trigger transformers
are each operative to ionize the excitation sources in the pump
chambers. Upon closing the switch, stored energy from the single
energy drive system flows into whichever excitation source has been
ionized and causes the laser associated with that lamp to discharge
its energy.
[0012] In certain embodiments, one or more of the lasers comprises
a laser capable of lasing at least two wavelengths in accordance
with the first aspects described above. In certain embodiments, the
laser workstation comprises a pulse dye laser (PDL) and an Nd:YAG
laser. The pulse dye laser in certain embodiments has an output of
575-650 nm, for example about 585 nm. The Nd:YAG laser comprises an
Nd:YAG laser resonator having an Nd:YAG lasing medium with a
longitudinal axis along which laser energy is emitted. An output
coupler is located at a first end of the Nd:YAG lasing medium along
the longitudinal axis of the Nd:YAG lasing medium. A first mirror
is located along the longitudinal axis of the Nd:YAG lasing medium
at a second end of the lasing medium, and a second mirror is
located along the longitudinal axis of the Nd:YAG lasing medium
between the first mirror and the lasing medium. The first mirror is
highly reflective at least 1064 nm. The second mirror is highly
reflective at 1320 nm and is substantially transparent at 1064 nm.
The second mirror in certain embodiments is treated to be
substantially transparent at 1064 nm, for example, by being coated
with a coating that is anti-reflective at 1064 nm. The Nd:YAG laser
resonator further comprises a beam block shutter that is opaque and
nonreflective. The beam block shutter is movable from a first
position along a longitudinal axis of the Nd:YAG lasing medium
between the first and second mirrors to a second position away from
the longitudinal axis of the Nd:YAG lasing medium. The Nd:YAG
lasing medium emits at both 1064 nm and at 1320 nm. Such an
arrangement advantageously permits the laser resonator to have all
of the critical optical components (the lasing medium, the mirrors
and the output coupler) mounted in a stationary fashion rather than
requiring a tuning element or switching of mirrors, resulting in a
robust and relatively maintenance-free workstation.
[0013] Under operation, the second mirror reflects the 1320 nm
radiation while permitting the 1064 nm radiation to pass. When the
beam block shutter is in the first position, along the light path
of the lasing medium, the beam block shutter prohibits the 1064 nm
radiation that passes through the second mirror from reaching the
first mirror and being reflected back into the lasing medium. Thus,
only the 1320 nm radiation is reflected, amplified and ultimately
emitted. When the beam block shutter is in the second position, out
of the longitudinal axis of the lasing medium and thus out of the
light path, the 1064 nm radiation passes through the second mirror
to the first mirror and is reflected back into the lasing medium.
The Nd:YAG lasing medium has a stimulated emission cross-section at
1064 nm that is much greater than the stimulated emission
cross-section at 1320 nm. Accordingly, an output coupler can be
selected such that the laser operates at 1064 nm.
[0014] In accordance with another aspect, laser workstations are
provided having two lasers and a single electronics drive system.
The single energy drive system is operatively connected by active
semiconductor switches to a first laser pump chamber that excites a
first lasing medium and to a second laser pump chamber that excites
a second lasing medium. The active semiconductor switches allow for
the selective release of portions of energy from a single energy
storage network, for example, a capacitor bank, to its associated
lamps and ultimately to the associated laser. The release of less
than the total amount of stored energy allows for the rapid or
immediate firing of either the first laser or the second laser in a
series of partial-energy releases, resulting in a series of
"sub-pulses" of laser energy of different wavelengths.
[0015] In certain embodiments of the various aspects described
above, the laser workstation further comprises a handpiece
operatively connected, for example, by means of a optical fiber or
a wave guide, to the pulse dye laser and to the Nd:YAG laser. The
handpiece in certain embodiments comprises a plurality of lenses
operative to image the laser radiation, optionally adjustably.
[0016] Methods of treating skin problems utilizing laser systems
disclosed herein are also provided. In one aspect, a laser system
in accordance with the first aspect is used to apply laser energy
at a first wavelength to an area of skin affected by a skin
problem. The same laser system is used to apply laser energy at a
second wavelength to the same area of skin. In this way, the skin
problem is treated with two different wavelengths of laser energy
from the same laser system, indeed from the same laser itself.
[0017] In another aspect, a laser system in accordance with those
disclosed herein is used to treat skin affected by a skin problem.
Laser energy from both the first laser and the second laser is
applied to the area of skin affected by a skin problem. Typically,
the wavelength of the laser energy from the first laser differs
from the wavelength of the energy from the second laser, such that
the area of skin can be treated with each of two beneficial
wavelengths of laser energy of different wavelengths in a single
treatment session. In certain embodiments, sub-pulses of laser
energy are utilized to treat skin affected by a skin problem. Such
a method has the advantage of permitting greater control over the
duration of time between applications of the different wavelengths
of laser energy, as well as permitting the two wavelengths to be
applied in a much shorter period of time, perhaps instantaneously.
These factors may lead to improved results in the treatment of skin
problems.
[0018] A more specific example of using multiple wavelength pulses
to treat a skin lesion is having a 595 nm wavelength generated with
a pulse dye laser and a 1064 nm wavelength generated with a
solid-state laser. To eradicate a vascular lesion, a pulse of 595
nm is followed by another pulse at 1064 nm radiating at the same
area of the skin lesion. The pulse at 595 nm at an effective
fluence converts the oxy-hemoglobin contained in the red blood
cells in the ecstatic vascular lesion to met-hemoglobin that has a
much higher absorption coefficient at a 1064 nm wavelength. With
the wavelength multiplexing technique mentioned, the treatment
efficacy is dramatically improved. The energy or fluence required
is thus dramatically reduced.
[0019] These and additional features and advantages of the
invention disclosed here will be further understood from the
following detailed disclosure of certain preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic representation of an embodiment of an
laser having a lasing medium capable of lasing at two
wavelengths;
[0021] FIG. 2A is an embodiment of a laser workstation;
[0022] FIG. 2B is an alternative embodiment of a portion of a laser
workstation;
[0023] FIG. 3A is a schematic representation of an embodiment of a
single electronics drive system;
[0024] FIG. 3B is a schematic representation of another embodiment
of a single electronics drive system;
[0025] FIG. 4A is an energy level diagram for a Nd:YAG laser;
[0026] FIG. 4B is an energy level diagram for a YAP:Nd:laser;
[0027] FIG. 5 is a schematic representation of an embodiment of the
laser apparatus as it is applied to a layer of skin; and
[0028] FIGS. 6A-6D are graphical representations of various
sub-pulse configurations.
[0029] The figures referred to above are not drawn necessarily to
scale and should be understood to present a representation of the
invention, illustrative of the principles involved. Some features
of the laser workstation depicted in the drawings have been
enlarged or distorted relative to others to facilitate explanation
and understanding. The same reference numbers are used in the
drawings for similar or identical components and features shown in
various alternative embodiments. Laser workstations, as disclosed
herein, will have configurations and components determined, in
part, by the intended application and environment in which they are
used.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0030] Lasers and laser workstations in accordance with the current
invention may be embodied in various forms. Certain embodiments are
described in further detail below.
[0031] FIG. 1 shows an embodiment of a laser, here an Nd:YAG laser.
The emittance at two wavelengths of the Nd:YAG laser is illustrated
in the energy level diagram of FIG. 4A. Other suitable lasers
include any laser capable of emitting at least two wavelengths and
include, for example, crystal lasing mediums, gas lasing mediums,
dye lasing mediums or other types of lasing media. For example, a
YAP:Nd lasing medium is capable of lasing at 1079 nm and/or at 1341
nm, as illustrated in the energy level diagram of FIG. 4B. Such a
medium is described in U.S. Pat. No. 6,613,040, which is hereby
incorporated herein in its entirety for all purposes. Other
suitable lasing media include but are not limited to other rare
earth and transition ion dopants as well as other crystal and glass
hosts of these dopants. Examples of such dopants include Erbium,
Chromium and Titanium. Examples of other hosts include fluoride
crystals such as YLF, vanadite crystals such as YVO and fluoride
glasses such as ZBLN and silica glasses. Other suitable lasing
media will be readily apparent to those of skill in the art, given
the benefit of this disclosure. Referring back to FIG. 1, Nd:YAG
laser resonator 200 has an Nd:YAG laser medium 202, here a crystal
rod, having a longitudinal axis 204. The Nd:YAG laser resonator 200
further comprises flashlamps 250 to excite the Nd:YAG laser medium.
Other suitable excitation means may be utilized, and such will be
readily apparent to those skilled in the art, given the benefit of
this disclosure. The Nd:YAG laser medium 202 and flashlamps 250 are
contained within pump chamber 260.
[0032] The Nd:YAG resonator further comprises a first mirror 210
and a second mirror 220. The first mirror 210 is highly reflective
at least 1064 nm. For example, in certain embodiments the first
mirror has a reflectance of at least 90%, for example at least 95%,
optionally at least 99.5% at 1064 nm. The second mirror is highly
reflective at 1320 nm and is substantially transparent at 1064 nm.
Substantially transparent, as used herein, means that the mirror
permits light at the given wavelength to pass through, in either
direction, to a sufficient extent to permit sufficient laser output
to be generated at that wavelength for the treatment of skin. In
other words, the mirror must be sufficiently nonreflective,
nonrefractive and nonabsorbent at said wavelength to permit
sufficient laser output to be generated at that wavelength for the
treatment of skin. The creation of such mirrors is known in the
art, and is accomplished, for example, by coating a mirror
comprised of a suitable material with a coating that is
anti-reflective at 1064 nm. Commercially available dielectric
coatings are commonly used in this application. Such coatings are
typically made up of multiple thin layers of dielectric materials
such as magnesium fluoride and heavy metal oxides. The Nd:YAG laser
resonator further comprises a receptacle for an output coupler 230.
The output coupler is chosen to be partially reflective to allow
the lasing medium to resonate while permitting laser output. The
mirrors and output coupler may be plane parallel, hemispherical or
spherical. Suitable configurations for the laser resonator will be
readily apparent to those skilled in the art, given the benefit of
his disclosure.
[0033] The Nd:YAG laser resonator further comprises a beam block
shutter 240 that is opaque and nonreflective at least at about 1064
nm. The beam block shutter is movable from a first position along
longitudinal axis 204 of the Nd:YAG lasing medium between the first
and second mirrors to a second position away from the longitudinal
axis of the Nd:YAG lasing medium. As is illustrated in FIG. 4, the
Nd:YAG lasing medium emits at both 1064 nm and at 1320 nm. The beam
block shutter permits the exclusion of 1064 nm light from reaching
the first mirror and thus from resonating and being emitted. With
the blocker in the first position along the longitudinal axis, and
thus in the light path, the Nd:YAG laser will emit only at 1320 nm.
With the shutter in the second position and thus removed from the
light path, both wavelengths are emitted. As the stimulated
emission cross-section for operation at 1064 nm is much greater
than that for operation at 1320 nm, it is a simple matter to select
an output coupler such that the laser in this mode will operate at
1064 nm. The configuration of the Nd:YAG laser resonator permits
the laser resonator to have all of the critical optical components
(the lasing medium, the mirrors and the output coupler) mounted in
a stationary fashion rather than requiring a tuning element or
switching of mirrors, resulting in a robust and relatively
maintenance-free workstation having three laser outputs while
utilizing only two lasers.
[0034] FIG. 2A shows an embodiment of a laser workstation. The
workstation comprises a main unit 510 that contains a pulse dye
laser and an Nd:YAG laser such as is illustrated in FIG. 1. A
calibration port 512 and a front control panel 514 are provided.
Footswitch 516 is used for convenient control. A swing arm 520
holds the optical delivery fiber 522 that ends in a handpiece 524.
The handpiece has a finger switch 526 as an alternate means for
activation. FIG. 2B shows an alternative embodiment that utilizes
an articulated arm 528 that is appropriate for a quartz fiber
delivery system. Other suitable configurations for other suitable
delivery systems will be readily apparent to those of skill in the
art, given the benefit of this disclosure.
[0035] The laser workstation comprises a pulse dye laser. Certain
embodiments of the laser workstation include a pulse dye laser
having a wavelength of between about 570 nm and 650 nm. Pulse dye
lasers and methods of utilizing such in the treatment of skin are
described in U.S. Pat. No. 6,077,294, which is hereby incorporated
by reference in its entirety for all purposes. The pulse dye laser
may in certain embodiments operate at a deep penetrating wavelength
of about 585 nm, so as to target hemoglobin of blood in skin
tissue. Hemoglobin absorbs this particular laser energy, with
resultant generation of heat. Heat is generated in the skin up to
about 1 mm to 1.2 mm in depth and typically uses energy of less
than 5 Joules per square cm. In certain embodiments, the pulse dye
laser has a target spot size of about 10 mm in diameter. In certain
embodiments, the pulse width of the pulse dye laser has a range of
150 microseconds to about 1500 microseconds, optionally with a
width of about 450 microseconds. The wavelength of the pulse dye
laser lies in a range of about 570 nanometers to about 650
nanometers, for example in a range of about 585 nanometers to about
600 nanometers. In certain embodiments, the pulse dye laser
operates at a wavelength of about 585 nanometers. The pulse dye
laser may provide a fluence of less than 5 Joules per square cm,
for example, 3 Joules per square cm at a 10-millimeter diameter
skin treatment spot. By treating the skin to this low fluence pulse
dye laser light, collagen may be stimulated to regenerate and "fill
in" valleys of wrinkles for a younger, more clear skin.
[0036] FIG. 3A illustrates a single electronics drive system
comprising two different lasers, here an Nd:YAG laser and a pulse
dye laser. Of course, any type of laser susceptible to excitation
by a suitable excitation source may be utilized in such an
arrangement. Suitable lasers include those described throughout
this specification and will be readily apparent to those of skill
in the art, given the benefit of this disclosure. Certain
embodiments may utilize as one of the lasers a laser capable of
emitting at least two wavelengths in accordance with those
described above. Referring to FIG. 3, each of the lasers is excited
by one or more flashlamps (not shown) that are operated by a single
electronics drive system 300. A single energy storage network 310
is connected by switch 314 to Nd:YAG pump chamber 316 and to dye
pump chamber 318. Switch 314 may be triggered by a foot petal, a
switch connected to a handpiece, or other by means. Switch 314 is
ordinarily opened. Between Nd:YAG pump chamber 316 and switch 314
is secondary winding 320 of Nd:YAG trigger transformer 322.
Similarly, between dye pump chamber 318 and switch 314 is secondary
winding 330 of dye trigger transformer 332. Trigger transformers
322 and 332 are high voltage trigger transformers. Each of the
secondary windings of the trigger transformers are in series with
flashlamps in Nd:YAG pump chamber 316 and dye pump chamber 318,
respectively, and act as inductors in discharge circuits of the
flashlamps. By providing a driving pulse to the primary windings
324, 334 of trigger transformers 322 and 332, respectively, the
lamps in either pump chamber can be ionized. When switch 314 is
then closed, energy from the energy storage network 310 will flow
through the pump chamber whose lamps have been previously ionized.
In this manner, a single energy storage and pulse discharge means
can be used to drive either laser pump chamber, further conserving
space and reducing size of the laser workstation. In other
embodiments, either or both of the lasers may be excited by any
known means capable of being ionized prior to discharge, for
example, by optical pumping, such as, for example, using a source
such as a pulsed ultraviolet source. Suitable excitation sources
will be readily apparent to those skilled in the art, given the
benefit of this disclosure.
[0037] The above embodiment allows the user to select the laser to
be fired and to discharge the full quantity of energy stored in the
energy storage network to that laser. Prior to firing the other
laser, or to re-firing the laser first selected, the energy storage
network must be recharged. An alternate embodiment that permits the
selective discharge of portions of the stored energy to the lasers
is exemplified in FIG. 3B. This embodiment comprises two different
lasers, here an Nd:YAG laser and a pulse dye laser. Again, any type
of laser susceptible to excitation by a suitable excitation source
may be utilized in such an arrangement. Suitable lasers include
those described throughout this specification, including those
capable of emitting at multiple wavelengths, and will be readily
apparent to those of skill in the art, given the benefit of this
disclosure. High voltage power supply 402 is operably connected to
capacitor bank 410 to charge one or more capacitors (not
illustrated) in the capacitor bank. The capacitors serve as an
energy storage system for the laser workstation. The capacitors are
operably connected to flashlamps 416 and 418, which serve to pump a
pulse dye laser (not illustrated), and to flashlamps 426 and 428,
which serve to pump an Nd:YAG laser (not illustrated). In the
embodiment illustrated herein, flashlamps 416 and 418 are arranged
in parallel such that they straddle the pulse dye laser, while
flashlamps 426 and 428 are arranged in series to accommodate the
full length of the Nd:YAG laser crystal, which is typically longer
than the pulse dye laser. Any arrangement of flashlamps in parallel
or in series will be readily accomplished by one of skill in the
art, given the benefit of this disclosure.
[0038] The capacitor bank 410 is connected to each of the
flashlamps 416, 418, 426 and 428 by insulated gate bipolar
transistors (IGBT's) 430, 432 and 434. In the case of flashlamps
426 and 428, which are arranged in series, a single IGBT 434
resides between the capacitor bank and the two flashlamps. While an
IGBT is illustrated in this embodiment, any active semiconductor
switch may be employed, for example, field effect transistors
(FET's) such as MOSFET, Jfet (Junction FET) Ujt (Unijunction FET),
or Darlington transistors and the like. Suitable active
semiconductor switches will be readily apparent to those of skill
in the art, given the benefit of this disclosure. The active
semiconductor switches may be controlled by a computer, allowing
for precision control over duration of time that they are closed
and thus the quantity of energy that they allow to pass when
closed. Such switches allow for the controlled and optionally
preprogrammed completion of the circuit such that discreet
quantities of energy, which may include the entirety of the energy
stored in the capacitor bank or only portions of the energy stored
in the capacitor bank, may be passed through to the flashlamps.
When less than the entirety of the stored energy is discharged into
a flashlamp, the excess of the stored energy remains to be
discharged into any of the flashlamps immediately. This allows for
numerous alternatives for arranging such partial pulses, or
"sub-pulses," to be delivered. For example, a sub-pulse from the
Nd:YAG laser could be followed by a sub-pulse from the pulse dye
laser in a time from of as low as 0-500 ms, as exemplified in FIG.
6A. As another example, repeated sub-pulses of laser energy from
the same laser, e.g. a "pulse train," can be achieved. For example,
a pulse train from the pulse dye laser can be followed by a pulse
train from the Nd:YAG laser, as illustrated in FIG. 6B, or for
rapid alteration or intercalated between the two lasers, as
exemplified in FIG. 6C. Optionally, both lasers may be fired
simultaneously or may overlap, as exemplified by the overlapping
sub-pulses of FIG. 6D. Of course, in any of these examples, either
the pulse dye laser or the Nd:YAG laser could be fired first. Any
such combination of sub-pulses is possible, limited only by the
quantity of energy that is stored in the capacitor bank and the
speed at which the IGBT operates. In the case of a laser resonator
that provides the option of emitting at different wavelengths, the
speed at which the resonator can switch from one wavelength to
another, e.g., the time for the beam block shutter to move from one
position to the next, is typically longer than the speed at which
the active semiconductor switch operates and serves to limit the
speed of firing at the different wavelengths. Further, depending on
the duration that the active semiconductor switches are closed, a
parameter which is actively controllable, the amount of energy
delivered by the sub-pulses can be varied, limited ultimately by
the total quantity of energy stored in the capacitor bank. Other
suitable combinations will be suggested by the particular use to
which the laser system is being employed, and will be readily
apparent to those of skill in the art, given the benefit of this
disclosure.
[0039] This system may advantageously allow for the delivery, via
the sum of the sub-pulses, of a greater amount of the energy stored
in the energy storage network than is achievable with a single
pulse. This may result in the energy storage system taking longer
to be recharged. Also, depending on the particular components used,
a second sub-pulse may start at a lower voltage than the first
sub-pulse. This lower voltage may enhance the discharge conditions
for the Nd:YAG laser but be less suited for the pulse dye laser,
meaning that better performance would be achieved by using the
pulse dye laser followed by the Nd:YAG laser. Suitable components
for this embodiment will be readily apparent to one of skill in the
art, given the benefit of this disclosure.
[0040] Flashlamps 416, 418, 426 and 428 are ignited and maintained
in a state of ionization by lamp simmer power supplies 440, which
are wired in parallel with the flashlamps. In this fashion, the
lamps are maintained in a state in which they can immediately be
utilized in accordance with the rapid fire techniques just
discussed.
[0041] Any of the above-described laser workstation embodiments may
further comprises a handpiece connected critically, by an optical
fiber or wave guide, to the pulse dye laser generator device and to
the Nd:YAG laser generator device. The handpiece may be connected
to each laser by means of a separate critical connection to each
laser head, or may optionally be connected to both lasers by means
of a single critical connection. The handpiece optionally focuses,
through a plurality of lenses, the laser light from the laser
generators onto a spot so as to stimulate skin rejuvenation. For
example, the handpiece may focus laser light from the pulse dye
laser onto a spot of about 10 mm in diameter to stimulate new
collagen growth beneath the epidermis without injuring the
surrounding structures.
[0042] Laser workstations in accordance with those described herein
can be utilized to treat a variety of skin conditions, including,
for example, aged skin, wrinkled skin, sun-damaged skin, acne or
acne-scarred skin, scars, undesirable veins such as leg or facial
veins and other vascular problems. For example, a method for the
treatment of wrinkles is provided in which the pulse dye laser is
utilized to stimulate collagen growth beneath the epidermal layer.
Such a method is exemplified in FIG. 5, which is a schematic
representation of an embodiment of the laser workstation comprising
laser system 10. Laser system 10 utilizes both a laser output
generator 12 having both a pulse dye laser and an Nd:YAG laser for
the treatment of skin. The pulse dye laser is tuned to deliver
light at a wavelength of about 585 nm and a pulse width in the
range of about 150 microseconds to about 1500 microseconds, for
example 450 microseconds. The laser output generator 12 is
operatively connected to a handpiece 14 by an optical fiber or wave
guide 16. The handpiece 14 focuses, through a plurality of lenses
22 and 24, the laser light "L" onto a spot "S" of about 10 mm in
diameter or larger, with a fluence typically of less than 5 Joules
per square cm, to reach hemoglobin "H" of blood in a collagen layer
beneath the surface of the wrinkled tissue. The laser energy is
absorbed by hemoglobin "H," resulting in heat being generated in
the skin tissue "T" in an area of up to about 1 mm in depth, which
stimulates new collagen growth beneath the epidermis "E".
[0043] Such treatments may beneficially utilize laser energy from
each laser head, or energy at each of the wavelengths available
from the Nd:YAG resonator. Without wishing to be bound by theory,
it is believed that the utilization of alternating wavelengths,
particularly rapidly alternating wavelengths, may provide
significant clinical advantages. For example, an initial sub-pulse
from the dye laser at 595 nm can be used to convert Oxy-hemoglobin
in a vessel from its common chemical form into Met-hemoglobin,
which provides much greater absorption at the 1064 nm wavelength of
the Nd:YAG laser. Thus, treatment of such vessels can be effected
at greatly reduced fluence, likely resulting in reduced side
effects. Other benefits will be readily apparent to those of skill
in the art, given the benefit of this disclosure. Further,
treatments may utilize any of the combinations of sub-pulses
described above that result from the use of active semiconductor
switches. Suitable methods of treating skin utilizing a laser
workstation in accordance with those described herein include the
treatment of facial telangiectasias or vascular legions with the
pulse dye laser at 595 nm; treatment of leg or facial veins with
the pulse dye laser at 595 nm and/or the Nd:YAG laser at 1064 nm;
treatment of active acne, acne scarring or other scars with the
pulse dye laser at 595 nm in combination with the Nd:YAG laser at
1320 nm; and treatment of sun-damaged or wrinkled skin with the
pulse dye laser at 595 nm and/or the Nd:YAG laser at 1320 nm. Other
suitable uses for the laser workstation will be readily apparent to
those skilled in the art, given the benefit of this disclosure.
[0044] While the invention has been described with respect to
specific examples including presently preferred modes of carrying
out the invention, those skilled in the art will appreciate that
there are numerous variations and permutations of the above
described systems and techniques that fall within the spirit and
scope of the invention as set forth in the appended claims.
* * * * *