U.S. patent application number 10/339585 was filed with the patent office on 2003-07-24 for method of forming blind holes in surgical needles using a diode pumped nd-yag laser.
Invention is credited to Irwin, Timothy L., Mosavi, Reza K..
Application Number | 20030136770 10/339585 |
Document ID | / |
Family ID | 23152352 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030136770 |
Kind Code |
A1 |
Mosavi, Reza K. ; et
al. |
July 24, 2003 |
Method of forming blind holes in surgical needles using a diode
pumped Nd-YAG laser
Abstract
A method of laser drilling surgical needles. The method utilizes
a diode pulsed laser to produce a laser beam consisting of a train
of high energy pulses.
Inventors: |
Mosavi, Reza K.; (Alto,
GA) ; Irwin, Timothy L.; (Rochester, NY) |
Correspondence
Address: |
AUDLEY A. CIAMPORCERO JR.
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
23152352 |
Appl. No.: |
10/339585 |
Filed: |
January 9, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10339585 |
Jan 9, 2003 |
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09864035 |
May 23, 2001 |
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09864035 |
May 23, 2001 |
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09298876 |
Apr 26, 1999 |
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6252195 |
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Current U.S.
Class: |
219/121.71 ;
219/121.7 |
Current CPC
Class: |
B23K 26/382 20151001;
A61B 2017/00526 20130101; B23K 26/40 20130101; B23K 26/389
20151001; A61B 2017/06028 20130101; A61B 2017/0608 20130101; B23K
2103/50 20180801; A61B 17/06066 20130101 |
Class at
Publication: |
219/121.71 ;
219/121.7 |
International
Class: |
B23K 026/38 |
Claims
1. A method of laser drilling surgical needles, the method
comprising the steps of: providing a diode pulsed laser Nd-YAG
drilling system; producing a train of laser pulses having
sufficient power to effectively drill a blind hole in a surgical
needle; directing the beam of laser pulsed onto a proximal end of a
surgical needle to produce a blind bore hole.
2. The method of claim 1 wherein the diode pulsed laser drilling
system comprises: a curved rear mirror; a first Nd-YAG rod; a
plurality of high power laser diode arrays; a partially
transmitting output coupler mirror; a solid state power supply to
drive the diode arrays; first and second beam bending flat mirrors;
a second Nd-YAG rod; a second plurality of high power laser diode
arrays; a beam expander; and, a focusing optics assembly.
3. The method of claim 1, wherein the beam has a power of about 5
watts to about 100 watts.
4. The method of claim 1 wherein the beam has a pulse width of
about 5 microseconds to about 1 millisecond.
5. The method of claim 1, wherein the frequency of the beam is from
about one pulse to about 100 kHz.
Description
TECHNICAL FIELD
[0001] The field of art to which this invention relates is surgical
needles, in particular, a method of drilling blind holes in
surgical needles using lasers.
BACKGROUND OF THE INVENTION
[0002] Surgical needles and attached sutures are well known in the
art. Surgical needles typically have a distal pointed end and a
proximal suture mounting end. The suture mounting end can have
several structural configurations for receiving a suture tip,
including channels and blind holes. The distal end of a suture is
typically mounted to the proximal end of a surgical needle in
several ways. For example the distal end or tip of the suture may
be inserted into a channel, and the channel is then mechanically
swaged to lock the suture in the channel. Or, the distal end or tip
of a suture may be mounted into a bore hole drilled into the
proximal end of a needle. The proximal end of the needle is then
mechanically swaged such that the suture end is mechanically locked
into the bore hole. Alternatively, sutures may be mounted to
surgical needles using adhesives, epoxies, shrink tubing and other
known mounting techniques.
[0003] The use of blind bore holes to mount sutures to surgical
needles has become the mounting method of choice for many types of
surgical needles. The needles having suture mounted in this manner
may have less resistance to penetration when moved through tissue.
Blind bore holes are typically drilled into the proximal ends of
needles using one of two conventional methods. One method of
drilling surgical needles is to use mechanical drills. The other
method of drilling blind bore holes is to use lasers. Mechanical
drilling is known to have several disadvantages including
mechanical alignment, tool wear, constant adjustments, the
inability to drill small diameter holes, and relative slowness of
the mechanical drilling process. The use of laser drilling
overcomes many of these problems. The laser uses a beam of light
energy to form the blind bore hole by liquifying the metal and
causing it to be expelled from the proximal end of the needle.
Accordingly, in laser drilling there is no mechanical contact with
needle by the drilling apparatus, tool wear is not a problem,
alignment problems and adjustments are minimized, and drilling is
considerably more time effective, allowing for high production
throughput.
[0004] Although the use of conventional laser systems to drill
surgical needles has many advantages, there are also some problems
which are attendant with their use. Laser drilling equipment is
typically more sophisticated and complex than mechanical drilling
equipment and requires highly skilled operators. In addition, the
laser drilling may produce a bore hole which does not have an
entirely smooth interior surface because of residual slag resulting
from the expulsion of the molten metal. The slag may interfere with
the insertion of a suture into a bore hole.
[0005] It is known that to produce a smooth bore hole it is
desirable to remove metal from a bore hole through evaporation and
plasma formation rather than a melting process. This can be done by
using pulsed Nd-YAG lasers. Such lasers produce a train of short
pulses having sufficient energy to remove small amounts of material
with each pulse, thereby producing a high quality bore hole. The
duration of the pulses is typically in the 10 microseconds to 100
micro seconds range.
[0006] Presently, short pulses for drilling surgical needles are
produced using a conventional flash lamp pumped Nd-YAG laser as an
oscillator to produce an optical pulse range from 200 microseconds
to 600 microseconds duration. This optical pulse is then intensity
modulated by an electro-optical modulator or similar device into a
plurality of short pulses (i.e., a pulse train). The duration of
these short pulses and their frequencies are controlled by the
modulator parameters. The pulse train then enters a conventional
flash lamp pumped Nd-YAG amplifier and is amplified to produce a
high power intensity beam. The high power intensity beam is then
focused on the rear or proximal end face of a surgical needle to
drill a blind hole into the proximal end of the needle.
[0007] Because of the inherent limitations of flash lamp pulsing,
the production of short pulses requires modulation of the main
pulse by means of an electro-optical modulator, which in turn
requires an optical polarizer and analyzer. The addition of these
optical devices along the path of the laser beam causes the loss of
some optical energy, and is associated with some difficulty in
keeping the optical devices optically aligned in the manufacturing
environment. The electro-optical modulator (Pockles Cell) requires
the use of high voltage electronics which in turn require high
maintenance and extensive safety precautions. The flash lamp pumped
laser oscillator and amplifier use both high voltage power supplies
and capacitor banks to store energy for discharging into the flash
lamp. The flash lamp is believed to be an inefficient way of
pumping a laser rod, since most of the energy is dissipated in the
form of heat which must be removed by a cooling system. The power
supply, capacitor banks, and cooling system require significant
amounts of space, maintenance and troubleshooting. The heat
dissipated in the laser rod from flash lamp operation also causes
thermal lensing of the rod, which deteriorates the quality of the
laser beam. Another problem observed with the existing flash lamp
pumped method is usable flash lamp life. The average flash lamp may
have a life of about 500 to 600 hours. This requires shutting down
the laser drilling system every 600 or so hours to replace the
flash lamp thereby interrupting production, and necessitating
maintenance and repair.
[0008] Accordingly, there is a need in this art for improved pulsed
laser systems which overcome the disadvantages of a flash lamp
pulsing system.
SUMMARY OF THE INVENTION
[0009] Therefore, it is an object of the present invention to
provide a method of pulsed laser drilling of surgical needles which
is efficient, and which eliminates the need for an optical
polarizer, an electro-optical modulator, an analyzer, a flash lamp
and associated power supplies and capacitor banks.
[0010] It is also an object of the present invention to provide for
a pulsed laser drilling system which is easier to cool, which has
reduced heating of the laser rod and reduced thermal lensing
effect, and which can operate significantly longer than a flash
lamp pumped system without having downtime.
[0011] Accordingly, a method of laser pulsed drilling of surgical
needles is disclosed. The method consists of providing a laser
drilling apparatus which utilizes an oscillator consisting of an
Nd-YAG crystal rod and a plurality of high power laser diode
arrays. An optical pulse is produced by the laser apparatus. The
pulse is focused on the proximal end of a surgical needle to make a
blind hole.
[0012] These and other advantages of the present invention will
become more apparent from the following description and
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic diagram of a flash lamp pulsed laser
drilling system of the prior art.
[0014] FIG. 2 is a schematic diagram of a typical optical pulse
produced by a flash lamp pumped Nd-YAG laser oscillator of the
prior art.
[0015] FIG. 3 is a schematic diagram illustrating a typical train
of pulses created by modulating the single optical pulse of FIG.
2.
[0016] FIG. 4 is a schematic view showing the train of pulses of
FIG. 3 after amplification.
[0017] FIG. 5 is a schematic diagram illustrating a laser diode
pumped Nd-YAG laser oscillator and amplified system of the present
invention useful for drilling surgical needles.
[0018] FIG. 6 is a schematic diagram illustrating a train of
optical pulses produced by the laser diode pumped Nd-YAG laser
oscillator of FIG. 5.
[0019] FIG. 7 is a schematic diagram illustrating the train of
pulses of FIG. 6 after amplification.
[0020] FIGS. 8A & B illustrate on an oscilloscope trace of
optical pulses produced by the laser diode pumped Nd-YAG laser
oscillator of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] A schematic diagram of a flash lamp pumped Nd-YAG laser
drilling system of the prior art is illustrated in FIG. 1. As seen
in FIG. 1, the system has a rear, convex 100% reflective mirror 10
aligned with a beam polarizer 20, and an Nd-YAG laser rod 40.
Adjacent to the Nd-YAG laser rod 40 is a flash lamp 30. Aligned
with laser rod 40 is an output coupler mirror 50. The combination
of the mirror 10, the beam polarizer 20, the flash lamp 30, the
laser rod 40, and the output coupler mirror 50 comprises the laser
oscillator 55. The flash lamp 30 pumps the Nd-YAG rod 40 into a
higher energy level, and the mirrors 10 and 50 cause the laser
oscillation to occur. The beam polarizer 20 linearly polarizes the
laser beam. An optical pulse 130, as illustrated in FIG. 2, then
exits the output coupler mirror 50 and reflects sequentially off of
a pair beam bending flat mirrors 60. The optical pulse 130 is
modulated by the electro-optical modulator 80 into a short pulse
train 140 as seen in FIG. 3. The pulse train 140 then goes into an
analyzer 90, and then enters the amplifier 95. Amplifier 95
consists of flash lamp 30 and Nd-YAG laser rod 40. The short pulse
train 140 is then amplified to pulse train 150 as seen in FIG. 4
and goes through the beam expander 100, and then the focusing
optics assembly 110 to form beam 160. Beam 160 is then directed at
the proximal end face 195 of the surgical needle 190 to form blind
hole 198.
[0022] Referring now to FIG. 5, a schematic of a preferred
embodiment of a laser diode pumped Nd-YAG laser system of the
present invention useful for drilling surgical needles is
disclosed. The system consists of a curved, 100% reflective rear
mirror 210, a beam bending prism 215, a small diameter Nd-YAG rod
240, a group of high power laser diode arrays 220, and a partially
transmitting outer coupler mirror 250. This establishes the laser
oscillator 255. A solid state power supply (not shown in FIG. 5)
drives the laser diode arrays for different powers, frequencies and
pulse widths. The driving frequencies can range up to 10k Hz. The
laser diode arrays 220 are made up of a number of diode bars. The
diode arrays 220 emit radiation pulses in the narrow spectral width
fitting to the small absorption bands of the Nd-YAG rod. The Nd-YAG
rod 240 is optically pumped by the laser diode arrays 220 in the
presence of the two mirrors 210 and 250, causing the laser
oscillation to occur. The pulse width and pulse frequency of the
Nd-YAG rod laser emission follows the pulse width and pulse
frequency of the diode arrays. Nd-YAG optical pulses in the range
of 5 microseconds to 100 microseconds can be produced. These pulses
come in the form of a pulse train 340 as seen in FIG. 6. The pulse
train 340 sequentially goes through a pair of beam bending flat
mirrors 260 before it is sent to the amplifier section 230.
Amplifier secion 230 consists of an Nd-YAG rod 240 and a group of
high power arrays 220. It should be noted that in both the laser
oscillator 255 and laser amplifier 230, the laser diode arrays 220
pump the Nd-YAG rod 240 along the side. The power of the high
powered laser diode bar 240 is in the range, preferably, of about
40 to 50 watts, and is sufficintly effective to produce the pulse
train desired. Each array 220 can have "N" number of bars and these
arrays can be arranged in different configurations around the
Nd-YAG rod to illuminate the rod. The amplified pulse train 350 as
seen in FIG. 7 is then sent to beam expander 300, and a focusing
optics assembly 310 where the laser beam 360 finally is focused on
the proximal end face 195 of surgical needle 190. When the
amplified high power short pulses 360 are focused on the end face
195 of needle 190, they remove metal in the form of evaporation and
plasma formation, which produces high quality blind holes 198.
[0023] The diode pumped Nd-YAG laser drilling systems of the
present invention have many advantages over the flash lamp pumped
systems of the prior art. Using the laser diode pulsed Nd-YAG laser
drilling systems of the present invention, it is now possible to
eliminate the optical polarizer, electro-optical modulator,
analyzer, flash lamp and its associated power supplies and
capacitor banks used in a conventional flash lamp pulsed
system.
[0024] In addition, it is now possible to obtain higher beam
quality due to the reduction of thermal lensing effect caused by
excessive heat input to the rod by flash lamp. Laser beam alignment
and maintenance are simpler and easier due to the elimination of
the pulse modulating system of the prior art.
[0025] The laser drilling systems of the present invention have
higher energy efficiency, and reduced laser downtime since it is no
longer necessary to replace flash lamps.
[0026] The 100% reflective rear mirrors useful in the laser systems
of the present invention include conventional, commercially
available curved reflective mirrors such as those available from
CVI Laser Optics Corp., Albuquerque, New Mexico, Lambda Research
Optics Inc., Cerritos, Calif., and Coherent Auburn Group, Auburn,
Calif. The size of the mirrors will preferably be about .O slashed.
0.5".times.0.25" thick. The reflective mirrors function to create
the lasing process.
[0027] The Nd-YAG laser rods useful in the laser systems of the
present invention include conventional, commercially available
small diameter rods such as 1.0% Nd-YAG. The size of the laser rods
will be sufficient to effectively convert enough of the 808 nm pump
light into 1064 nm lasing light. The size of the rods will
typically be from about .O slashed. 0 2.5 mm to about .O slashed.
6.0 mm, more typically about .O slashed. 2.5 mm.times.100 mm to
about .O slashed. 6.0 mm to 200 mm and preferably about .O slashed.
3.0 mm.times.140 mm to about .O slashed. 4.0 mm.times.140 mm. The
laser rods function to convert pump light energy into lasing light
energy. The laser rods are available from Litton Airtron Synoptcs,
Charlotte, N.C. as Part No. Nd:YAG 3.times.104 mm. The laser diode
bars are available from Coherent, Inc. as Part No.
ULPS156E/9/3.
[0028] The partially transmitting output coupler mirrors useful in
the practice of the present invention include conventional,
commercially available output coupler mirrors such as .O slashed.
0.5".times.0.25" thick dielectrically coated substrates.
[0029] The coupler mirrors function to maintain the lasing process
inside the resonator while at the same time allowing some of the
resonator light to exit.
[0030] The laser diode arrays useful in the systems of the present
invention include conventional, commercially available diode arrays
such as radial arrays. The diode arrays function to generate 808 nm
pump light energy. The diode arrays will typically consist of a
plurality of laser bars. The laser bars are conventional,
commercially available laser bars such as AlGaAs. The laser bars
function to convert electrical energy into 808 nm optical
energy.
[0031] The solid state power supplies useful to power the diode
arrays include conventional, commercially available power supplies
such as laser diode drive. The power supplies function to convert
standard wall plug electrical power into pulsed electrical power.
The capacity of the power supplies will be sufficient to
effectively provide pulsed electrical power. The power will
typically range from about 10 watts to about 500 watts, more
typically about 50 watts to about 400 watts, and preferably about
100 watts to about 350 watts.
[0032] The beam bending flat mirrors useful in the laser systems of
the present invention include conventional commercially available
beam bending flat mirrors such as dielectrically coated glass
substrates. The beam bending flat mirrors function to reflect laser
light energy.
[0033] The beam expander useful in the practice of the present
invention includes conventional, commercially available beam
expanders such as the ones from CVI Laser optics Corp. or Lambda
Research Optics Inc. and Coherent Auburn Group. The beam expander
functions to expand the diameter of the laser beam while at the
same time collimating the laser beam.
[0034] The focusing optics assemblies useful in the practice of the
method of the present invention includes conventional, commercially
available optics assemblies such as 100 mm or 150 mm focusing
lenses. The optics assembly functions to focus the laser light
energy into a small spot.
[0035] As mentioned previously, the parts used in the laser systems
of the present invention are commercially available. For example,
the rear mirror can be purchased from JML Direct Optics in
Rochester, N.Y. as Part No. MPC14700/505, the prism may be
purchased from JML Direct optics as Part No. PDC 16120/104, while
the output coupler mirror, the beam bending mirror, beam expander
and focusing lens can be purchased form JML Direct Optics as Part
Nos. CMN 11225/202/xxx, MCL 15100/505, 52340/104 and CLL 13745/104
respectively.
[0036] The laser beams used to drill surgical needles in the
process of the present invention will have power, pulse frequency,
and pulse width sufficiently effective to drill blind holes in
metal surgical needles. The power of the beam will typically be
about 5 watts to about 100 watts, more typically about 10 watts to
about 50 watts, and preferably about 25 watts to about 45 watts.
The pulse width of the beam will typically be about 5 microseconds
to about 1 millisecond, more typically about 7 microseconds to
about 200 microseconds, and preferably about 10 microseconds to
about 100 microseconds. The frequency of the beam will typically be
about single pulse to about 100 kHz, more typically about 1 kHz to
about 50 kHz, and preferably about 1.5 kHz to about 10 kHz. The
power of the beam is varied by varying the pulse energy and/or
pulse frequency. The frequency of the beam is varied by the
operator. The pulse width of the beam is varied by the
operator.
[0037] Although this invention has been shown and described with
respect to detailed embodiments thereof, it will be understood by
those skilled in the art the various changes in form and detail
thereof may be made without departing from the spirit and scope of
the claimed invention.
* * * * *