U.S. patent application number 11/823149 was filed with the patent office on 2008-06-26 for electromagnet energy distributions for electromagnetically induced mechanical cutting.
This patent application is currently assigned to BIOLASE Technology, Inc.. Invention is credited to Andrew I. Kimmel, Ioana M. Rizoiu.
Application Number | 20080151953 11/823149 |
Document ID | / |
Family ID | 25417081 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080151953 |
Kind Code |
A1 |
Rizoiu; Ioana M. ; et
al. |
June 26, 2008 |
Electromagnet energy distributions for electromagnetically induced
mechanical cutting
Abstract
Output optical energy pulses including relatively high energy
magnitudes at the beginning of each pulse are disclosed. As a
result of the relatively high energy magnitudes which lead each
pulse, the leading edge of each pulse includes a relatively large
slope. This slope is preferably greater than or equal to 5.
Additionally, the full-width half-max value of the output optical
energy distributions are between 0.025 and 250 microseconds and,
more preferably, are about 70 microseconds. A flashlamp is used to
drive the laser system, and a current is used to drive the
flashlamp. A flashlamp current generating circuit includes a solid
core inductor which has an inductance of 50 microhenries and a
capacitor which has a capacitance of 50 microfarads.
Inventors: |
Rizoiu; Ioana M.; (Dana
Point, CA) ; Kimmel; Andrew I.; (San Clemente,
CA) |
Correspondence
Address: |
STOUT, UXA, BUYAN & MULLINS LLP
4 VENTURE, SUITE 300
IRVINE
CA
92618
US
|
Assignee: |
BIOLASE Technology, Inc.
|
Family ID: |
25417081 |
Appl. No.: |
11/823149 |
Filed: |
June 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11523492 |
Sep 18, 2006 |
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11823149 |
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10993498 |
Nov 18, 2004 |
7108693 |
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11523492 |
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10164451 |
Jun 6, 2002 |
6821272 |
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10993498 |
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09883607 |
Jun 18, 2001 |
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10164451 |
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08903187 |
Jun 12, 1997 |
6288499 |
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09883607 |
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08522503 |
Aug 31, 1995 |
5741247 |
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08903187 |
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Current U.S.
Class: |
372/38.06 ;
372/51 |
Current CPC
Class: |
H01S 3/092 20130101;
B23K 26/146 20151001; B23K 26/38 20130101; B23K 26/356 20151001;
A61B 18/20 20130101; B23K 26/0622 20151001 |
Class at
Publication: |
372/38.06 ;
372/51 |
International
Class: |
H01S 3/0915 20060101
H01S003/0915 |
Claims
1. A flashlamp current generating circuit, comprising: a solid core
inductor having an inductance of about 50 microhenries; a capacitor
coupled to the inductor, the capacitor having a capacitance of 50
microfarads; and a flashlamp coupled to the solid core
inductor.
2. A pulse for driving a flashlamp that is used as a stimulation
source for a laser rod, comprising: a leading edge having a slope
which is greater than or equal to about 5, the slope being defined
on a plot of the pulse as y over x (y/x) where y is current in amps
and x is time in microseconds; and a full-width half-max value in a
range from 0.025 to 250 microseconds.
3. The pulse for driving a flashlamp as recited in claim 2, wherein
the full-width half-max value is in a range from 10 to 150
microseconds.
4. The pulse for driving a flashlamp as recited in claim 3, wherein
the full-width half-max value is about 70 microseconds.
5. The pulse for driving a flashlamp as recited in claim 2, wherein
the slope is greater than or equal to about 10.
6. The pulse for driving a flashlamp as recited in claim 2, wherein
the slope is greater than or equal to about 100.
7. The pulse for driving a flashlamp as recited in claim 6, wherein
the slope is about 240.
8. A method, comprising: focusing or placing a peak concentration
of energy into an interaction zone above a target; outputting
atomized fluid particles from a plurality of atomizers into the
interaction zone; and at least a portion of the atomized fluid
particles in the interaction zone highly absorbing at least a
portion of the energy and expanding, wherein disruptive forces are
imparted onto the target.
9. The method as recited in claim 8, wherein an output axis of a
first one of the plurality of atomizers is not parallel to an
output axis of a second one of the plurality of atomizers and both
of the output axes point toward the interaction zone.
10. The method as recited in claim 8, wherein the energy is
generated using the flashlamp current generating circuit of claim
1.
11. The method as recited in claim 8, wherein the energy is
generated using the pulse of claim 2
12. A flashlamp current generating circuit, comprising: an inductor
having an inductance less than about 16 microhenries; a capacitor
coupled to the inductor, the capacitor having a capacitance of 50
microfarads; and a flashlamp coupled to the inductor.
13. The flashlamp current generating circuit as recited in claim
12, wherein the inductor comprises an inductance within a range of
about 10 to 15 microhenries.
14. The flashlamp current generating circuit as recited in claim
12, wherein the inductor comprises a solid core inductor.
15. The flashlamp current generating circuit as recited in claim
14, wherein the a solid core inductor has a rated inductance of
about 50 microhenries.
Description
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 11/523,492, filed Sep. 18, 2006 (Att. Docket
BI9066CON4), the contents of all which are expressly incorporated
herein by reference. U.S. application Ser. No. 11/523,492 is a
continuation of U.S. application Ser. No. 10/993,498 (U.S. Pat. No.
7,108,693; Att. Docket BI9066CON3), which is a continuation of U.S.
application Ser. No. 10/164,451 (U.S. Pat. No. 6,821,272; Att
Docket BI9066CON2), which is a continuation of U.S. application
Ser. No. 09/883,607 (abandoned; Att Docket BI9066CON), which is a
continuation of U.S. application Ser. No. 08/903,187 (U.S. Pat. No.
6,288,499; Att Docket BI9066P), which is a continuation-in-part of
U.S. application Ser. No. 08/522,503 (U.S. Pat. No. 5,741,247; Att.
Docket BI9001P), all of which are commonly assigned and the
contents of which are expressly incorporated herein by reference.
This application is related to U.S. application Ser. No.
10/624,967, filed Jul. 21, 2003 (Att. Docket BI9001DIV2CON).
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to lasers and, more
particularly, to output optical energy distributions of lasers.
[0004] 2. Description of Related Art
[0005] A variety of laser systems are present in the prior art. A
solid-state laser system generally comprises a laser rod for
emitting coherent light and a stimulation source for stimulating
the laser rod to emit the coherent light. Flashlamps are typically
used as stimulation sources for Erbium laser systems, for example.
The flashlamp is driven by a flashlamp current, which comprises a
predetermined pulse shape and a predetermined frequency. The
flashlamp current drives the flashlamp at the predetermined
frequency, to thereby produce an output flashlamp light
distribution having substantially the same frequency as the
flashlamp current. This output flashlamp light distribution from
the flashlamp drives the laser rod to produce coherent light at
substantially the same predetermined frequency as the flashlamp
current. The coherent light generated by the laser rod has an
output optical energy distribution over time that generally
corresponds to the pulse shape of the flashlamp current.
[0006] The pulse shape of the output optical energy distribution
over time typically comprises a relatively gradually rising energy
that ramps up to a maximum energy, and a subsequent decreasing
energy over time. The pulse shape of a typical output optical
energy distribution can provide a relatively efficient operation of
the laser system, which corresponds to a relatively high ratio of
average output optical energy to average power inputted into the
laser system.
[0007] The prior art pulse shape and frequency may be suitable for
thermal cutting procedures, for example, where the output optical
energy is directed onto a target surface to induce cutting. New
cutting procedures, however, do not altogether rely on
laser-induced thermal cutting mechanisms. More particularly, a new
cutting mechanism directs output optical energy from a laser system
into a distribution of atomized fluid particles located in a volume
of space just above the target surface. The output optical energy
interacts with the atomized fluid particles causing the atomized
fluid particles to expand and impart electromagnetically-induced
mechanical cutting forces onto the target surface. As a result of
the unique interactions of the output optical energy with the
atomized fluid particles, typical prior art output optical energy
distribution pulse shapes and frequencies have not been especially
suited for providing optical electromagnetically-induced mechanical
cutting. Specialized output optical energy distributions are
required for optimal cutting when the output optical energy is
directed into a distribution of atomized fluid particles for
effectuating electromagnetically-induced mechanical cutting of the
target surface.
SUMMARY OF THE INVENTION
[0008] The output optical energy distributions of the present
invention comprise relatively high energy magnitudes at the
beginning of each pulse. As a result of these relatively high
energy magnitudes at the beginning of each pulse, the leading edge
of each pulse comprises a relatively large slope. This slope is
preferably greater than or equal to 5. Additionally, the full-width
half-max (FWHM) values of the output optical energy distributions
are greater than 0.025 microseconds. More preferably, the
full-width half-max values are between 0.025 and 250 microseconds
and, more preferably, are between 10 and 150 microseconds. The
full-width half-max value is about 70 microseconds in the
illustrated embodiment. A flashlamp is used to drive the laser
system, and a current is used to drive the flashlamp. A flashlamp
current generating circuit comprises a solid core inductor having
an inductance of about 50 microhenries and a capacitor having a
capacitance of about 50 microfarads.
[0009] The present invention, together with additional features and
advantages thereof, may best be understood by reference to the
following description taken in connection with the accompanying
illustrative drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a plot of flashlamp-driving current versus time
according to the prior art;
[0011] FIG. 2 is a plot of output optical energy versus time for a
laser system according to the prior art;
[0012] FIG. 3 is a schematic circuit diagram illustrating a circuit
for generating a flashlamp-driving current in accordance with the
present invention;
[0013] FIG. 4 is a plot of flashlamp-driving current versus time in
accordance with the present invention;
[0014] FIG. 5 is a plot of output optical energy versus time for a
laser system in accordance with the present invention;
[0015] FIG. 6 is a block diagram showing a fluid output used in
combination with an electromagnetic energy source having a
flashlamp driving circuit in accordance with the present
invention;
[0016] FIG. 7 illustrates one embodiment of an electromagnetic
cutter of the present invention;
[0017] FIGS. 8 and 9 illustrate a particular embodiment of an
electromagnetically induced cutter that can be used with the
invention;
[0018] FIG. 10 is a schematic block diagram illustrating an
electromagnetically induced disruptive cutter according to an
embodiment of the present invention;
[0019] FIG. 11 is an optical cutter with a focusing optic in
accordance with an embodiment of the present invention;
[0020] FIG. 12 illustrates a control panel for programming a
combination of atomized fluid particles according to an illustrated
embodiment;
[0021] FIG. 13 is a plot of particle size versus fluid pressure in
accordance with one implementation of the present invention;
[0022] FIG. 14 is a plot of particle velocity versus fluid pressure
in accordance with one implementation of the present invention;
[0023] FIG. 15 is a schematic diagram illustrating a fluid
particle, a source of electromagnetic energy, and a target surface
according to an embodiment of the present invention;
[0024] FIG. 16 is a schematic diagram illustrating a "grenade"
effect according to an embodiment of the present invention;
[0025] FIG. 17 is a schematic diagram illustrating an "explosive
ejection" effect according to an embodiment of the present
invention;
[0026] FIG. 18 is a schematic diagram illustrating an "explosive
propulsion" effect according to an embodiment of the present
invention;
[0027] FIG. 19 is a schematic diagram illustrating a combination of
FIGS. 16-18;
[0028] FIG. 20 is a schematic diagram illustrating a "cleanness" of
cut obtained by one implementation of the present invention;
and
[0029] FIG. 21 is a schematic diagram illustrating a roughness of
cut obtained by a prior art system.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0030] Referring more particularly to the drawings, FIG. 1
illustrates a plot of flashlamp-driving current versus time
according to the prior art. The flashlamp-driving current 10
initially ramps up to a maximum value 12. The initial ramp 14
typically comprises a slope (current divided by time) of between 1
and 4. After reaching the maximum value 12, the flashlamp-driving
current 10 declines with time, as illustrated by the declining
current portion 16. The prior art flashlamp-driving current 10 may
typically comprise a frequency or repetition rate of 1 to 15 hertz
(Hz). Additionally, the flashlamp-driving current 10 of the prior
art may typically comprise a pulse width greater than 300
microseconds. The full-width half-max value of the
flashlamp-driving current 10 is typically between 250 and 300
microseconds. The full-width half-max value is defined as a value
of time corresponding to a length of the full-width half-max range
plotted on the time axis. The full-width half-max range is defined
on the time axis from a beginning time, where the amplitude first
reaches one half of the peak amplitude of the entire pulse, to an
ending time, where the amplitude reaches one half of the peak
amplitude a final time within the pulse. The full-width half-max
value is the difference between the beginning time and the ending
time.
[0031] FIG. 2 illustrates a plot of energy versus time for the
output optical energy of a typical prior art laser. The output
optical energy distribution 20 generally comprises a maximum value
22, an initial ramp 24, and a declining output energy portion 26.
The micropulses 28 correspond to population inversions within the
laser rod as coherent light is generated by stimulated emission.
The average power of the laser can be defined as the power
delivered over a predetermined period of time, which typically
comprises a number of pulses. The efficiency of the laser system
can be defined as a ratio of the output optical power of the laser,
to the input power into the system that is required to drive the
flashlamp. Typical prior art laser systems are designed with
flashlamp-driving currents 10 and output optical energy
distributions 20 which optimize the efficiency of the system.
[0032] FIG. 3 illustrates a flashlamp-driving circuit 30 according
to the presently preferred embodiment. The flashlamp-driving
circuit 30 comprises a high-voltage power supply 33, a capacitor
35, a rectifier 37, an inductor 39, and a flashlamp 41. The
capacitor 35 is connected between the high-voltage power supply 33
and ground, and the flashlamp 41 is connected between the inductor
39 and ground. The high-voltage power supply 33 preferably
comprises a 1500 volt source, having a charging rate of 1500 Joules
per second. The flashlamp 41 may comprise a 450 to 700 torr source
and, preferably, comprises a 450 torr source. The capacitor 35
preferably comprises a 50 microfarad capacitor, and the rectifier
37 preferably comprises a silicon-controlled rectifier. The
inductor 39 preferably comprises a 50 microhenry solid-core
inductor. In alternative embodiments, the inductor 39 may comprise
a 13 microhenry inductance. In still other alternative embodiments,
the inductor 39 may comprise inductance values of between 10 and 15
micro-henries. Other values for the inductor 39 and the capacitance
35 may be implemented in order to obtain flashlamp-driving currents
having relatively large leading amplitudes, for example, as
discussed below.
[0033] FIG. 4 illustrates the flashlamp driving current 50 of the
present invention, which passes from the inductor 39 to the
flashlamp 41. The flashlamp driving current of the present
invention preferably has a pulse width which is greater than about
0.25 microseconds and, more preferably, which is in a range of 100
to 300 mircoseconds. In the illustrated embodiment, the pulse width
is about 200 microseconds. The flashlamp driving current 50
comprises a maximum value 52, an initial ramp portion 54, and a
declining current portion 56. The flashlamp 41 preferably comprises
a cylindrical glass tube having an anode, a cathode, and a gas
therebetween such as Xenon or Krypton. An ionizer circuit (not
shown) ionizes the gas within the flashlamp 41. As the
flashlamp-driving current 50 is applied to the anode of the
flashlamp 41, the potential between the anode and the cathode
increases. This potential increases as the flashlamp-driving
current increases, as indicated by the initial ramp 54. Current
flows through the gas of the flashlamp 41, resulting in the
flashlamp 41 emitting bright incoherent light.
[0034] The flashlamp 41 is close-coupled to laser rod (not shown),
which preferably comprises a cylindrical crystal. The flashlamp 41
and the laser rod are positioned parallel to one another with
preferably less than 1 centimeter distance therebetween. The laser
rod is suspended on two plates, and is not electrically connected
to the flashlamp-driving current circuit 30. Although the flashlamp
41 comprises the preferred means of stimulating the laser rod,
other means are also contemplated by the present invention. Diodes,
for example, may be used instead of flashlamps for the excitation
source. The use of diodes for generating light amplification by
stimulated emission is discussed in the book Solid-State Laser
Engineering, Fourth Extensively Revised and Updated Edition, by
Walter Koechner, published in 1996, the contents of which are
expressly incorporated herein by reference.
[0035] The incoherent light from the presently preferred flashlamp
41 impinges on the outer surface of the laser rod. As the
incoherent light penetrates into the laser rod, impurities within
the laser rod absorb the penetrating light and subsequently emit
coherent light. The impurities may comprise erbium and chromium,
and the laser rod itself may comprise a crystal such as YSGG, for
example. The presently preferred laser system comprises either an
Er, Cr:YSGG solid state laser, which generates electromagnetic
energy having a wavelength in a range of 2.70 to 2.80 microns, or
an erbium, yttrium, aluminum garnet (Er:YAG) solid state laser,
which generates electromagnetic energy having a wavelength of 2.94
microns. As presently preferred, the Er, Cr:YSGG solid state laser
has a wavelength of approximately 2.78 microns and the Er:YAG solid
state laser has a wavelength of approximately 2.94 microns.
According to one alternative embodiment, the laser rod may
comprises a YAG crystal, and the impurities may comprise erbium
impurities. A variety of other possibilities exist, a few of which
are set forth in the above-mentioned book Solid-State Laser
Engineering, Fourth Extensively Revised and Updated Edition, by
Walter Koechner, published in 1996, the contents of which are
expressly incorporated herein by reference. Other possible laser
systems include an erbium, yttrium, scandium, gallium garnet
(Er:YSGG) solid state laser, which generates electromagnetic energy
having a wavelength in a range of 2.70 to 2.80 microns; an erbium,
yttrium, aluminum garnet (Er:YAG) solid state laser, which
generates electromagnetic energy having a wavelength of 2.94
microns; chromium, thulium, erbium, yttrium, aluminum garnet
(CTE:YAG) solid state laser, which generates electromagnetic energy
having a wavelength of 2.69 microns; erbium, yttrium orthoaluminate
(Er:YAL03) solid state laser, which generates electromagnetic
energy having a wavelength in a range of 2.71 to 2.86 microns;
holmium, yttrium, aluminum garnet (Ho:YAG) solid state laser, which
generates electromagnetic energy having a wavelength of 2.10
microns; quadrupled neodymium, yttrium, aluminum garnet (quadrupled
Nd:YAG) solid state laser, which generates electromagnetic energy
having a wavelength of 266 nanometers; argon fluoride (ArF) excimer
laser, which generates electromagnetic energy having a wavelength
of 193 nanometers; xenon chloride (XeCl) excimer laser, which
generates electromagnetic energy having a wavelength of 308
nanometers; krypton fluoride (KrF) excimer laser, which generates
electromagnetic energy having a wavelength of 248 nanometers; and
carbon dioxide (C02), which generates electromagnetic energy having
a wavelength in a range of 9 to 11 microns.
[0036] Particles, such as electrons, associated with the impurities
absorb energy from the impinging incoherent radiation and rise to
higher valence states. The particles that rise to metastable levels
remain at this level for periods of time until, for example, energy
particles of the radiation excite stimulated transitions. The
stimulation of a particle in the metastable level by an energy
particle results in both of the particles decaying to a ground
state and an emission of twin coherent photons (particles of
energy). The twin coherent photons can resonate through the laser
rod between mirrors at opposing ends of the laser rod, and can
stimulate other particles on the metastable level, to thereby
generate subsequent twin coherent photon emissions. This process is
referred to as light amplification by stimulated emission. With
this process, a twin pair of coherent photons will contact two
particles on the metastable level, to thereby yield four coherent
photons. Subsequently, the four coherent photons will collide with
other particles on the metastable level to thereby yield eight
coherent photons.
[0037] The amplification effect will continue until a majority of
particles, which were raised to the metastable level by the
stimulating incoherent light from the flashlamp 41, have decayed
back to the ground state. The decay of a majority of particles from
the metastable state to the ground state results in the generation
of a large number of photons, corresponding to an upwardly rising
micropulse (64, for example, FIG. 5). As the particles on the
ground level are again stimulated back up to the metastable state,
the number of photons being emitted decreases, decreases,
corresponding to a downward slope in the micropulse 64, for
example. The micropulse continues to decline, corresponding to a
decrease in the emission of coherent photons by the laser system.
The number of particles stimulated to the metastable level
increases to an amount where the stimulated emissions occur at a
level sufficient to increase the number of coherent photons
generated. As the generation of coherent photons increases, and
particles on the metastable level decay, the number of coherent
photons increases, corresponding to an upwardly rising
micropulse.
[0038] The output optical energy distribution over time of the
laser system is illustrated in FIG. 5 at 60. The output optical
energy distribution of the present invention preferably has a pulse
width that is greater than about 0.25 microseconds and, more
preferably, in a range of 125 to 300 mircoseconds. In the
illustrated embodiment, the pulse width is about 200 microseconds.
The output optical energy distribution 60 comprises a maximum value
62, a number of leading micropulses 64, 66, 68, and a portion of
generally declining optical energy 70.
[0039] According to the present invention, the output optical
energy distribution 60 comprises a large magnitude. This large
magnitude corresponds to one or more sharply-rising micropulses at
the leading edge of the pulse. As illustrated in FIG. 5, the
micropulse 68 comprises a maximum value 62 which is at or near the
very beginning of the pulse. Additionally, the full-width half-max
value of the output optical energy distribution in FIG. 5 is
approximately 70 microseconds, compared to full-width half-max
values of the prior art typically ranging from 250 to 300
microseconds. Applicant's invention contemplates pulses comprising
full-width half-max values greater than 0.025 microseconds and,
preferably, ranging from 10 to 150 microseconds, but other ranges
may also be possible. Additionally, Applicant's invention
contemplates a pulse width of between 0.25 and 300 microseconds,
for example, compared to typical prior-art pulse widths which are
greater than 300 microseconds. Further, a frequency of 20 Hz is
presently preferred. Alternatively, a frequency of 30 Hz may be
used. Applicants' invention generally contemplates frequencies
between 1 and 100 Hz, compared to prior art frequencies typically
ranging from 1 to 15 Hz.
[0040] As mentioned above, the full-width half-max range is defined
from a beginning time, where the amplitude first rises above
one-half the peak amplitude, to an ending time, where the amplitude
falls below one-half the peak amplitude a final time during the
pulse width. The full-width half-max value is defined as the
difference between the beginning time and the ending time.
[0041] The location of the full-width half-max range along the time
axis, relative to the pulse width, is closer to the beginning of
the pulse than the end of the pulse. The location of the full-width
half-max range is preferably within the first half of the pulse
and, more preferably, is within about the first third of the pulse
along the time axis. Other locations of the full-width half-max
range are also possible in accordance with the present invention.
The beginning time preferably occurs within the first 10 to 15
microseconds and, more preferably, occurs within the first 12.5
microseconds from the leading edge of the pulse. The beginning
time, however, may occur either earlier or later within the pulse.
The beginning time is preferably achieved within the first tenth of
the pulse width.
[0042] Another distinguishing feature of the output optical energy
distribution 70 is that the micropulses 64, 66, 68, for example,
comprise approximately one-third of the maximum amplitude 62. More
preferably, the leading micropulses 64, 66, 68 comprise an
amplitude of approximately one-half of the maximum amplitude 62. In
contrast, the leading micropulses of the prior art, as shown in
FIG. 2, are relatively small in amplitude.
[0043] The slope of the output optical energy distribution 60 is
greater than or equal to 5 and, more preferably, is greater than
about 10. In the illustrated embodiment, the slope is about 50. In
contrast, the slope of the output optical energy distribution 20 of
the prior art is about 4.
[0044] The output optical energy distribution 60 of the present
invention is useful for maximizing a cutting effect of an
electromagnetic energy source 32, such as a laser driven by the
flashlamp driving circuit 30, directed into an atomized
distribution of fluid particles 34 above a target surface 3, as
shown in FIG. 6. An apparatus for directing electromagnetic energy
into an atomized distribution of fluid particles above a target
surface is disclosed in U.S. Pat. No. 5,741,247, entitled ATOMIZED
FLUID PARTICLES FOR ELECTROMAGNETICALLY INDUCED CUTTING, the entire
contents of which are incorporated herein by reference. The
high-intensity leading micropulses 64, 66, and 68 impart large
amounts of energy into atomized fluid particles which preferably
comprise water, to thereby expand the fluid particles and apply
mechanical cutting forces to the target surface of, for example,
tooth enamel, tooth dentin, tooth cementum, bone, and cartilage,
skin, mucosa, gingiva, muscle, heart, liver, kidney, brain, eye or
vessels. The trailing micropulses after the maximum micropulse 68
have been found to further enhance the cutting efficiency.
According to the present invention, a single large leading
micropulse 68 may be generated or, alternatively, two or more large
leading micropulses 68 (or 64, 66, for example) may be
generated.
[0045] The flashlamp current generating circuit 30 of the present
invention generates a relatively narrow pulse, which is on the
order of 0.25 to 300 microseconds, for example. Additionally, the
full-width half-max value of the optical output energy distribution
60 of the present invention preferably occurs within the first 70
microseconds, for example, compared to full-width half-max values
of the prior art occurring within the first 250 to 300
microseconds. The relatively quick frequency, and the relatively
large initial distribution of optical energy in the leading portion
of each pulse of the present invention, results in efficient
mechanical cutting. If a number of pulses of the output optical
energy distribution 60 were plotted, and the average power
determined, this average power would be relatively low, compared to
the amount of energy delivered to the laser system via the
high-voltage power supply 33. In other words, the efficiency of the
laser system of the present invention may be less than typical
prior art systems.
[0046] FIG. 7 shows an embodiment of an electromagnetically induced
disruptive cutter, according to an aspect of the present invention,
in which a fiberoptic guide 61, an air tube 63, and a fluid tube,
such as a water tube 65, are placed within a hand-held housing 67.
The fluid tube 65 can be operated under a relatively low pressure,
and the air tube 63 can be operated under a relatively high
pressure.
[0047] According to one aspect of the present invention, the laser
energy from the fiberoptic guide 61 focuses onto a combination of
air and fluid, from the air tube 63 and the fluid tube 65, at an
interaction zone 59. Fluid particles (e.g., atomized fluid
particles) in the air and fluid mixture absorb energy from the
laser energy of the fiberoptic tube 61, and explode. The explosive
forces from these atomized fluid particles can in certain
implementations impart disruptive (e.g., mechanical) cutting forces
onto the target 57.
[0048] The electromagnetically induced disruptive cutter of the
present invention uses the laser energy to expand fluid particles
(e.g., atomized fluid particles) to thus impart disruptive cutting
forces onto the target surface. The atomized fluid particles are
heated, expanded, and cooled before contacting the target surface.
The electromagnetically induced disruptive cutter of the present
invention can use a relatively small amount of water and, further,
can use only a small amount of laser energy to expand atomized
fluid particles generated from the water. According to the
electromagnetically induced disruptive cutter of the present
invention, additional water may not be needed to cool the area of
surgery, since the exploded atomized fluid particles are cooled by
exothermic reactions before they contact the target surface. Thus,
atomized fluid particles of the present invention are heated,
expanded, and cooled before contacting the target surface. The
electromagnetically induced disruptive cutter of the present
invention is thus capable of cutting without charring or
discoloration.
[0049] FIGS. 8 and 9 illustrate another embodiment of the
electromagnetically induced mechanical cutter. The atomizer for
generating atomized fluid particles comprises a nozzle 71, which
may be interchanged with other nozzles (not shown) for obtaining
various spatial distributions of the atomized fluid particles,
according to the type of cut desired. A second nozzle 72, shown in
phantom lines, may also be used. In a simple embodiment, a user
controls the air and water pressure entering into the nozzle 71.
The nozzle 71 is thus capable of generating many different
user-specified combinations of atomized fluid particles and
aerosolized sprays. The nozzle 71 is employed to create an
engineered combination of small particles of the chosen fluid. The
nozzle 71 may comprise several different designs including liquid
only, air blast, air assist, swirl, solid cone, etc. When fluid
exits the nozzle 71 at a given pressure and rate, it is transformed
into particles of user-controllable sizes, velocities, and spatial
distributions. The cone angle may be controlled, for example, by
changing the physical structure of the nozzle 71. For example,
various nozzles 71 may be interchangeably placed on the
electromagnetically induced disruptive cutter. Alternatively, the
physical structure of a single nozzle 71 may be changed.
[0050] The emitted energy may have an output optical energy
distribution that may be useful for achieving or maximizing a
cutting effect of an electromagnetic energy source, such as a
laser, directed toward a target surface. The cutting and/or
ablating effects created by the energy may occur on or at the
target surface, within the target surface, and/or above the target
surface. For instance, using desired optical energy distributions,
it is possible to disrupt a target surface by directing
electromagnetic energy toward the target surface so that a portion
of the energy is absorbed by fluid wherein fluid absorbing the
energy may be on the target surface, within the target surface,
above the target surface, or a combination thereof.
[0051] FIG. 10 is a block diagram illustrating a
electromagnetically induced disruptive cutter system of the present
invention. As shown in FIG. 10, an electromagnetic energy source
351 is coupled to both a controller 353 and a delivery system 355.
The delivery system 355 imparts cutting forces onto the target
surface 357. In one implementation, the delivery system 355
comprises a fiberoptic guide 23 (FIG. 8) for routing energy from
the electromagnetic energy source 351 through an optional
interaction zone 359 and toward the target surface 357.
[0052] Referring to FIG. 11, an optical cutter according to one
aspect of the present invention is shown, wherein a fiber guide
tube 5, a water line 7, and an air line 9 may be fed into the
optical cutter. A cap 15 fits onto the optical cutter and is
secured via threads. The fiber guide tube 5 abuts within a
cylindrical metal piece 19. Another cylindrical metal piece 21 is a
part of the cap 15. When the cap 15 is threaded onto the optical
cutter, the two cylindrical metal pieces/tubes 19 and 21 are moved
into close proximity of one another. The laser energy exits from
the fiber guide tube 23 and is applied to a target surface within
the patient's mouth, according to a predetermined surgical
plan.
[0053] Water from the water line 7 and pressurized air from the air
line 9 are forced into a mixing chamber, which is disposed
proximally of a mesh screen 31. The air and water mixture is very
turbulent in the mixing chamber, and exits this chamber through the
mesh screen 31, and through an aperture through which the fiber
guide tube 23 extends, moving distally. The air and water mixture
travels distally along the outside of the fiber guide tube 23, and
then leaves the tube 23 and contacts the area of surgery. Air and
water spray leaving the distal tip of the fiber guide tube 23 help
to cool the target surface being cut and to remove materials cut by
the laser.
[0054] The optical cutter further comprising a focusing optic 335
between the two metal cylindrical objects 19 and 21. The focusing
optic 335 prevents undesired dissipation of laser energy from the
fiber guide tube 5. Although shown coupling two fiber guide tubes
having optical axes disposed in a straight line, the focusing optic
335 may be implemented/modified in other embodiments: to couple
fiber guide tubes having non parallel optical axes (e.g., two fiber
guide tubes having perpendicularly aligned optical axes); to
facilitate rotation of one or both of the fiber guide tubes about
its respective optical axis; and/or to consist of or comprise one
or more of a mirror, pentaprism, or other light directing or
transmitting medium. Specifically, energy from the fiber guide tube
5 dissipates slightly before being focused by the focusing optic
335. The focusing optic 335 focuses energy from the fiber guide
tube 5 into the fiber guide tube 23.
[0055] Intense energy emitted from the fiberoptic guide 23 can be
generated from a coherent source, such as a laser. In an
illustrative embodiment, the laser comprises an erbium, chromium,
yttrium, scandium, gallium garnet (Er, Cr:YSGG) solid state laser,
which generates light having a wavelength in a range of 2.70 to
2.80 microns. As presently embodied, this laser has a wavelength of
approximately 2.78 microns. Fluid emitted from the optical cutter
(e.g., screen 31 and/or nozzle 71 of FIG. 8) comprises water in an
illustrated embodiment, other fluids may be used and appropriate
wavelengths of the electromagnetic energy source may be selected to
allow for high absorption by the fluid. Other possible laser
systems include an erbium, yttrium, scandium, gallium garnet
(Er:YSGG) solid state laser, which generates electromagnetic energy
having a wavelength in a range of 2.70 to 2.80 microns; an erbium,
yttrium, aluminum garnet (Er:YAG) solid state laser, which
generates electromagnetic energy having a wavelength of 2.94
microns; chromium, thulium, erbium, yttrium, aluminum garnet
(CTE:YAG) solid state laser, which generates electromagnetic energy
having a wavelength of 2.69 microns; erbium, yttrium orthoaluminate
(Er:YALO3) solid state laser, which generates electromagnetic
energy having a wavelength in a range of 2.71 to 2.86 microns;
holmium, yttrium, aluminum garnet (Ho:YAG) solid state laser, which
generates electromagnetic energy having a wavelength of 2.10
microns; quadrupled neodymium, yttrium, aluminum garnet (quadrupled
Nd:YAG) solid state laser, which generates electromagnetic energy
having a wavelength of 266 nanometers; argon fluoride (ArF) excimer
laser, which generates electromagnetic energy having a wavelength
of 193 nanometers; xenon chloride (XeCl) excimer laser, which
generates electromagnetic energy having a wavelength of 308
nanometers; krypton fluoride (KrF) excimer laser, which generates
electromagnetic energy having a wavelength of 248 nanometers; and
carbon dioxide (CO2), which generates electromagnetic energy having
a wavelength in a range of 9.0 to 10.6 microns.
[0056] The delivery system 355 of FIG. 10 is depicted comprising a
fluid output. In exemplary embodiments implementing a fluid output,
water can be chosen as a preferred fluid because of its
biocompatibility, abundance, and low cost. The actual fluid used
may vary as long as it is properly matched (meaning it is highly
absorbed) to the selected electromagnetic energy source (i.e.
laser) wavelength. The delivery system 355 can comprise an atomizer
for delivering user-specified combinations of atomized fluid
particles into the interaction zone 359. The controller 353
controls various operating parameters of the laser 351, and further
controls specific characteristics of the user-specified combination
of atomized fluid particles output from the delivery system 355,
thereby mediating cutting effects on and/or within the target
357.
[0057] In one embodiment, an output optical energy distribution
includes a plurality of high-intensity leading micropulses,
comprising high peak amounts of energy, that are directed toward a
target surface. The energy is directed toward the target surface to
obtain the desired cutting effects. For example, the energy may be
directed into atomized fluid particles, as discussed above. The
output optical energy distribution may also include one or more
trailing micropulses after the maximum leading micropulse that may
further help with removal of material. According to the present
invention, a single large leading micropulse may be generated or,
alternatively, two or more large leading micropulses may be
generated. In accordance with one aspect of the present invention,
relatively steeper slopes of the pulse and shorter duration of the
pulses may lower an amount of residual heat produced in the
material.
[0058] The output optical energy distribution may be generated by a
flashlamp current generating circuit that is configured to generate
a relatively narrow pulse, which is on the order of 0.25 to 300
microseconds, for example. Additionally, the full-width half-max
value of the optical output energy distribution of the present
invention can occur within the first 30 to 70 microseconds, for
example, compared to full-width half-max values of the prior art
occurring within the first 250 to 300 microseconds. The relatively
quick frequency, and the relatively large initial distribution of
optical energy in the leading portion of each pulse of the present
invention, can result in relatively efficient disruptive cutting
(e.g., mechanical cutting). The output optical energy distributions
of the present invention can be adapted for cutting, shaping and
removing tissues and materials, and further can be adapted for
imparting electromagnetic energy into atomized fluid particles over
a target surface, or other fluid particles located on or within the
target surface. The cutting effect obtained by the output optical
energy distributions of the present invention can be both clean and
powerful and, additionally, can impart consistent cuts or other
disruptive forces onto target surfaces.
[0059] Referring back to the figures, and in particular FIG. 12, a
control panel 377 for allowing user-programmability of the atomized
fluid particles is illustrated. By changing the pressure and flow
rates of the fluid, for example, the user can control the atomized
fluid particle characteristics. These characteristics determine
absorption efficiency of the laser energy, and the subsequent
cutting effectiveness of the electromagnetically induced disruptive
cutter. This control panel may comprise, for example, a fluid
particle size control 378, a fluid particle velocity control 379, a
cone angle control 380, an average power control 381, a repetition
rate 382, and a fiber selector 383.
[0060] FIG. 13 illustrates a plot 385 of mean fluid particle size
versus pressure. According to this figure, when the pressure
through the nozzle 71 is increased, the mean fluid particle size of
the atomized fluid particles decreases. The plot 387 of FIG. 14
shows that the mean fluid particle velocity of these atomized fluid
particles increases with increasing pressure.
[0061] According to one implementation of the present invention,
materials can be removed from a target surface at least in part by
disruptive cutting forces, instead of by conventional (e.g.,
thermal) cutting forces. In such implementations, energy is used
only to induce disruptive forces onto the targeted material. Thus,
the atomized fluid particles act as the medium for transforming the
electromagnetic energy of the laser into the disruptive (e.g.,
mechanical) energy required to achieve the disruptive cutting
effect of the present invention. The disruptive (e.g., mechanical)
interaction of the present invention can be safer, faster, and can
in certain implementations attenuate or eliminate negative thermal
side-effects typically associated with conventional laser cutting
systems.
[0062] The fiberoptic guide 23 (e.g., FIG. 8) can be placed into
close proximity of the target surface. This fiberoptic guide 23,
however, does not actually contact the target surface. Since the
atomized fluid particles from the nozzle 71 are placed into the
interaction zone 59, the purpose of the fiberoptic guide 23 is for
placing laser energy into this interaction zone, as well. One
feature of the present invention is the cleaning effect of the air
and water, from the nozzle 71, on the fiberoptic guide 23. The
present inventors have found that this cleaning effect is optimal
when the nozzle 71 is pointed somewhat directly at the target
surface. For example, debris from the disruptive cutting can be
removed by the spray from the nozzle 71.
[0063] Additionally, applicants have found that this orientation of
the nozzle 71, pointed toward the target surface, can enhance the
cutting efficiency of the present invention. Each atomized fluid
particle contains a small amount of initial kinetic energy in the
direction of the target surface. When electromagnetic energy from
the fiberoptic guide 23 contacts an atomized fluid particle, the
spherical exterior surface of the fluid particle acts as a focusing
lens to focus the energy into the water particle's interior.
[0064] As shown in FIG. 15, the water particle 401 has an
illuminated side 403, a shaded side 405, and a particle velocity
407. The focused electromagnetic energy is absorbed by the water
particle 401, causing the interior of the water particle to heat
and explode rapidly. This exothermic explosion cools the remaining
portions of the exploded water particle 401. The surrounding
atomized fluid particles further enhance cooling of the portions of
the exploded water particle 401. A pressure-wave is generated from
this explosion. This pressure-wave, and the portions of the
exploded water particle 401 of increased kinetic energy, are
directed toward the target surface 407. The incident portions from
the original exploded water particle 401, which are now traveling
at high velocities with high kinetic energies, and the
pressure-wave, impart strong, concentrated, disruptive (e.g.,
mechanical) forces onto the target surface 407.
[0065] These disruptive forces cause the target surface 407 to
break apart from the material surface through a "chipping away"
action. The target surface 407 does not undergo vaporization,
disintegration, or charring. The chipping away process can be
repeated by the present invention until the desired amount of
material has been removed from the target surface 407. Unlike prior
art systems, certain implementations of the present invention may
not require a thin layer of fluid. In fact, while not wishing to be
limited, a thin layer of fluid covering the target surface may in
certain implementations interfere with the above-described
interaction process. In other implementations, a thin layer of
fluid covering the target surface may not interfere with the
above-described interaction process.
[0066] FIGS. 16, 17 and 18 illustrate various types of absorptions
of the electromagnetic energy by atomized fluid particles. The
nozzle 71 can be configured to produce atomized sprays with a range
of fluid particle sizes narrowly distributed about a mean value.
The user input device for controlling cutting efficiency may
comprise a simple pressure and flow rate gauge or may comprise a
control panel as shown in FIG. 12, for example. Upon a user input
for a high resolution cut, relatively small fluid particles are
generated by the nozzle 71. Relatively large fluid particles are
generated for a user input specifying a low resolution cut. A user
input specifying a deep penetration cut causes the nozzle 71 to
generate a relatively low density distribution of fluid particles,
and a user input specifying a shallow penetration cut causes the
nozzle 71 to generate a relatively high density distribution of
fluid particles. If the user input device comprises the simple
pressure and flow rate gauge, then a relatively low density
distribution of relatively small fluid particles can be generated
in response to a user input specifying a high cutting efficiency.
Similarly, a relatively high density distribution of relatively
large fluid particles can be generated in response to a user input
specifying a low cutting efficiency. Other variations are also
possible.
[0067] These various parameters can be adjusted according to the
type of cut and the type of tissue. Hard tissues include tooth
enamel, tooth dentin, tooth cementum, bone, and cartilage. Soft
tissues, which the electromagnetically induced disruptive cutter of
the present invention is also adapted to cut, include skin, mucosa,
gingiva, muscle, heart, liver, kidney, brain, eye, and vessels.
Other materials may include glass and semiconductor chip surfaces,
for example. A user may also adjust the combination of atomized
fluid particles exiting the nozzle 71 to efficiently implement
cooling and cleaning of the fiberoptic 23 (FIG. 8), as well.
According to an illustrated embodiment, the combination of atomized
fluid particles may comprise a distribution, velocity, and mean
diameter to effectively cool the fiberoptic guide 23, while
simultaneously keeping the fiberoptic guide 23 clean of particular
debris which may be introduced thereon by the surgical site.
[0068] Looking again at FIG. 15, electromagnetic energy contacts
each atomized fluid particle 401 on its illuminated side 403 and
penetrates the atomized fluid particle to a certain depth. The
focused electromagnetic energy is absorbed by the fluid, inducing
explosive vaporization of the atomized fluid particle 401.
[0069] The diameters of the atomized fluid particles can be less
than, almost equal to, or greater than the wavelength of the
incident electromagnetic energy. In each of these three cases, a
different interaction occurs between the electromagnetic energy and
the atomized fluid particle. FIG. 16 illustrates a case where the
atomized fluid particle diameter is less than the wavelength of the
electromagnetic energy (d<lambda.). This case causes the
complete volume of fluid inside of the fluid particle 401 to absorb
the laser energy, inducing explosive vaporization. The fluid
particle 401 explodes, ejecting its contents radially. Applicants
refer to this phenomena as the "explosive grenade" effect. As a
result of this interaction, radial pressure-waves from the
explosion are created and projected in the direction of
propagation. The direction of propagation is toward the target
surface 407, and in one embodiment, both the laser energy and the
atomized fluid particles are traveling substantially in the
direction of propagation.
[0070] The resulting portions from the explosion of the water
particle 401, and the pressure-wave, produce the "chipping away"
effect of cutting and removing of materials from the target surface
407. Thus, according to the "explosive grenade" effect shown in
FIG. 16, the small diameter of the fluid particle 401 allows the
laser energy to penetrate and to be absorbed violently within the
entire volume of the liquid. Explosion of the fluid particle 401
can be analogized to an exploding grenade, which radially ejects
energy and shrapnel. The water content of the fluid particle 401 is
evaporated due to the strong absorption within a small volume of
liquid, and the pressure-waves created during this process produce
the material cutting process.
[0071] FIG. 17 shows a case where the fluid particle 401 has a
diameter, which is approximately equal to the wavelength of the
electromagnetic energy (d approximately equal to lambda). According
to this "explosive ejection" effect, the laser energy travels
through the fluid particle 401 before becoming absorbed by the
fluid therein. Once absorbed, the fluid particle's shaded side
heats up, and explosive vaporization occurs. In this case, internal
particle fluid is violently ejected through the fluid particle's
shaded side, and moves rapidly with the explosive pressure-wave
toward the target surface. As shown in FIG. 17, the laser energy is
able to penetrate the fluid particle 401 and to be absorbed within
a depth close to the size of the particle's diameter. The center of
explosive vaporization in the case shown in FIG. 17 is closer to
the shaded side 405 of the moving fluid particle 401. According to
this "explosive ejection" effect shown in FIG. 17, the vaporized
fluid is violently ejected through the particle's shaded side
toward the target surface 407.
[0072] A third case shown in FIG. 18 is the "explosive propulsion"
effect. In this case, the diameter of the fluid particle is larger
than the wavelength of the electromagnetic energy (d>lambda). In
this case, the laser energy penetrates the fluid particle 401 only
a small distance through the illuminated surface 403 and causes
this illuminated surface 403 to vaporize. The vaporization of the
illuminated surface 403 tends to propel the remaining portion of
the fluid particle 401 toward the targeted material surface 407.
Thus, a portion of the mass of the initial fluid particle 401 is
converted into kinetic energy, to thereby propel the remaining
portion of the fluid particle 401 toward the target surface with a
high kinetic energy. This high kinetic energy is additive to the
initial kinetic energy of the fluid particle 401. The effects shown
in FIG. 18 can be visualized as a micro-hydro rocket with a jet
tail, which helps propel the particle with high velocity toward the
target surface 407. The exploding vapor on the illuminated side 403
thus supplements the particle's initial forward velocity.
[0073] The combination of FIGS. 16-18 is shown in FIG. 19. The
nozzle 71 produces the combination of atomized fluid particles
which are transported into the interaction zone 59. Laser is
focused on this interaction zone 59. Relatively small fluid
particles 431 explode via the "grenade" effect, and relatively
large fluid particles 433 explode via the "explosive propulsion"
effect. Medium sized fluid particles, having diameters
approximately equal to the wavelength of the laser and shown by the
reference number 435, explode via the "explosive ejection" effect.
The resulting pressure-waves 437 and exploded fluid particles 439
impinge upon the target surface 407. FIG. 20 illustrates the clean,
high resolution cut produced by the electromagnetically induced
disruptive cutter of the present invention. Unlike the cut of the
prior art shown in FIG. 21, the cut of the present invention can be
clean and precise. Among other advantages, this cut can provide an
ideal bonding surface, can be accurate, and may not stress
remaining materials surrounding the cut.
[0074] An illustrated embodiment of light delivery for medical
applications of the present invention is through a fiberoptic
conductor, because of its light weight, lower cost, and ability to
be packaged inside of a handpiece of familiar size and weight to
the surgeon, dentist, or clinician. Non-fiberoptic systems may be
used in both industrial applications and medical applications, as
well. The nozzle 71 is employed to create an engineered combination
of small particles of the chosen fluid. The nozzle 71 may comprise
several different designs including liquid only, air blast, air
assist, swirl, solid cone, etc. When fluid exits the nozzle 71 at a
given pressure and rate, it is transformed into particles of
user-controllable sizes, velocities, and spatial distributions.
[0075] Although an exemplary embodiment of the invention has been
shown and described, many other changes, modifications and
substitutions, in addition to those set forth in the above
paragraphs, may be made by one having ordinary skill in the art
without necessarily departing from the spirit and scope of this
invention.
* * * * *