U.S. patent application number 09/877283 was filed with the patent office on 2004-07-29 for apparatus and method of directing a laser beam to a thermally managed beam dump in a laser system.
Invention is credited to Benneyworth, Edward Malcolm, Gabura, A. James, Nield, Scott Allen, Stenton, William Conrad, Trusty, Robert M..
Application Number | 20040146078 09/877283 |
Document ID | / |
Family ID | 32736665 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040146078 |
Kind Code |
A1 |
Nield, Scott Allen ; et
al. |
July 29, 2004 |
APPARATUS AND METHOD OF DIRECTING A LASER BEAM TO A THERMALLY
MANAGED BEAM DUMP IN A LASER SYSTEM
Abstract
An optical bench for processing laser light in a laser system,
including an optical bench housing, a beam dump mounted to the
optical bench housing so as to be in optical communication
therewith, steering optics mounted within the optical bench housing
for directing the laser light in a path from a laser light input to
an output, and a mechanism for causing the laser light to deviate
from the path and be directed into the beam dump upon recognition
of a specified condition in the laser system, wherein the laser
light is thermally isolated from the steering optics. The mechanism
can either cause at least one optically reflective element to be
inserted into the path, cause at least one optical element of the
steering optics to have a change in position with respect to the
path, and/or causes at least one optical element of the steering
optics to be removed from the path.
Inventors: |
Nield, Scott Allen;
(Reading, OH) ; Trusty, Robert M.; (Cincinnati,
OH) ; Stenton, William Conrad; (Midland, CA) ;
Gabura, A. James; (Midland, CA) ; Benneyworth, Edward
Malcolm; (Midland, CA) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
32736665 |
Appl. No.: |
09/877283 |
Filed: |
June 8, 2001 |
Current U.S.
Class: |
372/34 |
Current CPC
Class: |
H01S 5/02 20130101; H01S
5/4025 20130101; H01S 5/06825 20130101 |
Class at
Publication: |
372/034 |
International
Class: |
H01S 003/13 |
Claims
What is claimed is:
1. An optical bench for processing laser light in a laser system,
comprising: (a) an optical bench housing; (b) a beam dump mounted
to said optical bench housing so as to be in optical communication
therewith; (c) steering optics mounted within said optical bench
housing for directing said laser light in a path from a laser light
input to an output; and (d) a mechanism for causing said laser
light to deviate from said path and be directed into said beam dump
upon recognition of a specified condition in said laser system;
wherein said laser light is thermally isolated from said steering
optics.
2. The optical bench of claim 1, wherein said mechanism includes at
least one optically reflective element to be inserted into said
path.
3. The optical bench of claim 2, said mechanism further comprising:
(a) an optically reflective element movable into and out of said
path; (b) a shutter arm attached to said optically reflective
element; (c) a power source for moving said shutter arm; and (d) a
processor for controlling said power source.
4. The optical bench of claim 3, further comprising a device for
sensing a position of said optically reflective element and
communicating said position to said processor.
5. The optical bench of claim 1, wherein said mechanism is
deactivated upon recognition of a specified condition.
6. The optical bench of claim 1, wherein said mechanism causes at
least one optical element of said steering optics to have a change
of position with respect to said path.
7. The optical bench of claim 1, wherein said mechanism causes at
least one optical element of said steering optics to be removed
from said path.
8. The optical bench of claim 1, further comprising an optical
filter positioned in said laser light path for reflecting light
outside a specified wavelength range into said beam dump.
9. The optical bench of claim 1, said beam dump further comprising:
(a) a substantially conical beam dump housing having a closed end
and an open end, wherein a cavity is formed therein; (b) a layer of
material disposed within said beam dump cavity for absorbing laser
light directed into said beam dump; and (c) a plurality of fins
disposed on an exterior surface of said beam dump housing; wherein
heat contained within said absorber layer is conducted to said beam
dump housing and said fins.
10. The optical bench of claim 9, said beam dump further comprising
a window positioned over said open end of said beam dump housing to
create a seal for said cavity, wherein physical effects of said
laser light in said beam dump are isolated from said steering
optics.
11. The optical bench of claim 9, wherein said absorber layer is
made of a single material.
12. A laser system, comprising: (a) a laser for providing laser
light; (b) a first optical fiber in optical communication with said
laser light; (c) a second optical fiber; (d) an optical bench for
directing said laser light from said first optical fiber to said
second optical fiber, said optical bench further comprising; (1) an
optical bench housing; (2) a beam dump mounted to said optical
bench housing so as to be in optical communication therewith; (3)
steering optics mounted within said optical bench housing for
directing said laser light in a path from said first optical fiber
to said second optical fiber; and (4) a mechanism for causing said
laser light to deviate from said path and be directed into said
beam dump upon recognition of a specified condition in said laser
system, wherein said laser light is thermally isolated from said
steering optics; and (e) a processor for controlling said
mechanism.
13. The laser system of claim 12, wherein said mechanism includes
at least one optically reflective element to be inserted into said
path.
14. The optical bench of claim 13, said mechanism further
comprising: (a) an optically reflective element movable into and
out of said path; (b) a shutter arm attached to said optically
reflective element; and (c) a power source for moving said shutter
arm, wherein said processor controls said power source for moving
said optically reflective element.
15. The laser system of claim 14, further comprising a device for
sensing a position of said optically reflective element and
communicating said position to said processor.
16. The laser system of claim 12, wherein said mechanism is
deactivated upon recognition of a specified condition.
17. The laser system of claim 12, wherein said mechanism causes at
least one optical element of said steering optics to have a change
of position with respect to said path.
18. The laser system of claim 12, wherein said mechanism causes at
least one optical element of said steering optics to be removed
from said path.
19. The laser system of claim 12, said optical bench further
comprising an optical filter positioned in said laser light path
for reflecting light outside a specified wavelength range into said
beam dump.
20. The laser system of claim 12, said beam dump further
comprising: (a) a substantially conical beam dump housing having a
closed end and an open end, wherein a cavity is formed therein; (b)
a layer of material disposed within said beam dump cavity for
absorbing laser light directed into said beam dump; and (c) a
plurality of fins disposed on an exterior surface of said beam dump
housing; wherein heat contained within said absorber layer is
conducted to said beam dump housing and said fins.
21. The laser system of claim 20, said beam dump further comprising
a window positioned over said open end of said beam dump housing to
create a seal for said cavity, wherein physical effects of said
laser light in said beam dump are isolated from said steering
optics.
22. The laser system of claim 20, wherein said absorber layer is
made of a single material.
23. A method of preventing laser light in a laser system from being
directed in a path through an optical bench into optical
communication with an optical fiber, said method comprising the
following steps: (a) sensing a specified condition in said laser
system; (b) causing said laser light to deviate from said path into
a beam dump upon recognition of said specified condition; and (c)
thermally isolating said laser light from said optical bench.
24. The method of claim 23, further comprising the step of
physically isolating said laser light from said optical bench.
25. The method of claim 23, further comprising the step of
reflecting laser light outside a specified wavelength range into
said beam dump.
26. The method of claim 23, said laser light deviation step further
comprising the step of inserting an optically reflective element in
said optical bench into said path.
27. The method of claim 26, further comprising the steps of: (a)
sensing a position of said optically reflective element; and (b)
communicating said position to a processor controlling movement of
said optically reflective element.
28. The method of claim 23, said laser light deviation step further
comprising the step of removing an optical element in said optical
bench from said path.
29. The method of claim 23, said laser light deviation step further
comprising the step of repositioning an optical element in said
optical bench with respect to said path.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an optical bench for a
laser system and, more particularly, to a laser system having an
optical bench with steering optics to direct a laser beam to a
thermally managed beam dump upon recognition of certain
conditions.
[0002] It is well known that energy generators in the form of laser
systems have been utilized to treat many disease states through
surgical procedures. Such laser systems typically have a safety
mechanism included therein to block emission of the laser beam in
case an emergency situation or other anomaly occurs. One exemplary
safety mechanism for performing this function involves a metal
plate which is movable into the laser light path when the laser
system detects an abnormal condition. While this mechanism is able
to perform its intended safety function by effectively blocking the
laser light, the metal plate is unable to absorb the light energy
from the laser without a corresponding temperature increase within
the optical bench of the laser system. This has had the adverse
effect of causing thermal damage to the optics of the laser system.
The laser light may also discharge particles and debris from the
metal plate, which can scatter over the optical elements and cause
physical damage thereto. Accordingly, the optics of a laser system
will typically need to be refurbished or replaced when such a
safety device has been activated.
[0003] In light of the foregoing concerns, as well as the continued
need for safety mechanisms in laser treatment systems, it would be
advantageous to have a safety mechanism that does not cause damage
to the laser optics when activated. An optical bench of a laser
treatment system with such a safety mechanism would therefore have
the ability to manage the thermal energy dissipated from the laser
beam and keep damaging energy and damaging particles away from the
optics. It would also be desirable in this regard for the laser
treatment system to include a beam dump which is thermally
separated from the optics.
BRIEF SUMMARY OF THE INVENTION
[0004] In accordance with a first aspect of the present invention,
an optical bench for processing laser light in a laser system is
disclosed as including an optical bench housing, a beam dump
mounted to the optical bench housing so as to be in optical
communication therewith, steering optics mounted within the optical
bench housing for directing the laser light in a path from a laser
light input to an output, and a mechanism for causing the laser
light to deviate from the path and be directed into the beam dump
upon recognition of a specified condition in the laser system,
wherein the laser light is thermally isolated from the steering
optics. The mechanism can either cause at least one optically
reflective element to be inserted into the path, cause at least one
optical element of the steering optics to have a change in position
with respect to the path, and/or cause at least one optical element
of the steering optics to be removed from the path.
[0005] In accordance with a second aspect of the present invention,
a laser system is disclosed as including a laser for providing
laser light, a first optical fiber in optical communication with
the laser light, a second optical fiber, and an optical bench for
directing the laser light from the first optical fiber to the
second optical fiber. The optical bench further includes an optical
bench housing, a beam dump mounted to the optical bench housing so
as to be in optical communication therewith, steering optics
mounted within the optical bench housing for directing the laser
light in a path from the laser to the second optical fiber, and a
mechanism for causing the laser light to deviate from the path and
be directed into the beam dump upon recognition of a specified
condition in the laser system, wherein the laser light is thermally
isolated from said steering optics. A processor is also provided
for controlling the mechanism. The mechanism can either cause at
least one optically reflective element to be inserted into the
path, cause at least one optical element of the steering optics to
have a change in position with respect to the path, and/or cause at
least one optical element of the steering optics to be removed from
the path.
[0006] In accordance with a third aspect of the present invention,
a method of preventing laser light from being directed in a path
through an optical bench into optical communication with an optical
fiber is disclosed as including the steps of sensing a specified
condition in the laser system, causing the laser light to deviate
from the path into a beam dump upon recognition of the specified
condition, and thermally isolating the laser light from the optical
bench.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] While the specification concludes with claims particularly
pointing out and distinctly claiming the present invention, it is
believed that the same will be better understood from the following
description taken in conjunction with the accompanying drawings in
which:
[0008] FIG. 1 is an isometric view of a laser treatment system in
accordance with the present invention having an optical fiber
connectable thereto;
[0009] FIG. 2 is an isometric view of the laser treatment system of
FIG. 1, where the housing has been removed so as to enable viewing
of a controller board and the exterior of an optical bench
therein;
[0010] FIG. 3 is a section view of the optical bench depicted in
FIG. 2, where the steering optics therein are in a normal operating
position so as to allow a laser beam used for medical treatment
procedures to pass through the optical bench and into the optical
fiber;
[0011] FIG. 4 is an isometric view of the optical bench depicted in
FIGS. 2 and 3, where a connect block and a sensor board are shown
as being attached thereto; and
[0012] FIG. 5 is a section view of the optical bench as depicted in
FIG. 3, where the steering optics therein are in a fail-safe
operating position so as to direct the laser beam into a thermally
managed beam dump.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring now to the drawings in detail, wherein identical
numerals indicate the same elements throughout the figures, FIG. 1
depicts a laser treatment system 10 for transferring energy to
human tissue by means of light from an optical fiber 20. A first
laser diode is provided in laser treatment system 10 to produce a
first laser beam 14 having a predetermined power (preferably in a
range of approximately 2-20 watts) and a predetermined wavelength
(preferably in a range of approximately 800-850 nanometers) useful
for the medical treatment of disease. As further seen in FIG. 1, a
connect block 16 is located within a front portion of a housing 18
for laser treatment system 10. Connect block 16 assists first laser
beam 14 in being optically linked with a first end 22 of optical
fiber 20 via a connector 24 so that first laser beam 14 can be
transmitted from a second end (or tip) 26 of optical fiber 20.
[0014] FIG. 2 depicts laser treatment system 10 with housing 18
removed so as to expose an optical bench, identified generally by
reference numeral 34, in order to direct first laser beam 14 into
optical communication with optical fiber first end 22 during normal
operation. A controller board 28 is also shown that includes, among
other components, a main processor 30 for receiving and processing
electronic signals to control the operation of laser treatment
system 10. As explained in greater detail herein, main processor 30
provides energy to certain optical components within optical bench
34 when laser treatment system 10 is operational. In this way, main
processor 30 is able to prevent first laser beam 14 from entering
optical fiber 20 upon recognition of an anomalous condition by
removing energy from such optical components. It will also be
appreciated that the optical components of optical bench 34 will
preferably prevent first laser beam 14 from entering optical fiber
20 when laser system 10 is not operational (i.e., not lasing) as a
failsafe feature. While other anomalous conditions will be
identified herein, it will be understood that main processor 30
will deactivate such optical components when laser treatment system
10 detects unwanted conditions such as high tissue temperature,
charring of the tissue, or an over-stressed or broken fiber.
[0015] With regard to the operation of optical bench 34, it will be
seen from FIGS. 3 and 4 that the path of first laser beam 14
preferably enters optical bench 34 via an optical fiber 13 in
optical communication with the first laser diode. Optical fiber 13
is positioned within a connector 35 in optical bench 34 to assure
proper alignment. First laser beam 14 is transmitted through a beam
collimator 54 containing a lens 56 and is preferably directed
toward a total internal reflection (TIR) prism 58 mounted to a
housing 60 for optical bench 34. First laser beam 14 preferably
reflects off TIR prism 58 and is received by a first beamsplitter
62, which reflects first laser beam 14 toward a second beamsplitter
64. First laser beam 14 is then reflected from second beamsplitter
64 through an output beam lens assembly 66 and an output lens 68 so
as to place first laser beam 14 in optical communication with
optical fiber first end 22 via connector 24. It will be appreciated
that a small percentage of first laser beam 14 (identified by
reference numeral 15) is preferably transmitted by first
beamsplitter 62 to a laser power detector 70 by means of a turning
mirror 72 so that the power output of first laser beam 14 can be
monitored. Further explanation of first beamsplitter 62, laser
power detector 70, and laser beam 15 is provided in a related
patent application filed concurrently herewith entitled "Apparatus
And Method Of Monitoring And Controlling Power Output Of A Laser
System," having Ser. No. ______, which is owned by the assignee of
the present invention and hereby incorporated by reference. Of
course, various filters may be employed to better isolate and
attenuate the wavelength of light provided by first laser beam 14,
as exemplified by filter 74, correction filter 76, and neutral
density filter 78.
[0016] Similarly, a second laser diode preferably provides a second
laser beam 82, also known herein as a marker laser beam, to optical
bench 34 by means of an optical fiber 81. Optical fiber 81 is
positioned within a connector 85 in optical bench 34 to assure
proper alignment. Second laser beam 82 is transmitted through a
marker beam collimator 84, a marker lens 86, and a marker filter 87
attached to optical bench housing 60. Marker laser beam 82
preferably has a predetermined power (preferably in a range of
approximately 0.5-2 milliwatts) and a predetermined wavelength
(preferably in a range of approximately 600-650 nanometers). It
will be appreciated that marker laser beam 82 is preferably used as
the light source to optically stimulate a fluorescent slug in
optical fiber 20 so as to generate a desired optical fluorescent
response therefrom. In order to place marker laser beam 82 in
optical communication with optical fiber first end 22 via connector
24, it is directed toward a first laser turning mirror 88 which
reflects it to a second laser turning mirror 90. Marker laser beam
82 then impacts first beamsplitter 62, which transmits most of
marker laser beam 82 (as a function of its wavelength) so that it
passes therethrough to second beamsplitter 64. Marker laser beam 82
then reflects off second beamsplitter 64 and through output beam
lens assembly 66 and output lens 68. Accordingly, both first
(treatment) laser beam 14 and second (marker) laser beam 82 are
routed from first beamsplitter 62 to second beamsplitter 64, as
indicated by reference numeral 92, into first end 22 of optical
fiber 20 during normal operation of laser treatment system 10.
[0017] It will be appreciated that marker laser beam 82 provides an
optical stimulus to the fluorescent slug in optical fiber second
end 26, which absorbs the energy of marker laser beam 82 and
fluoresces in response thereto. The time delay from stimulation of
the fluorescent slug by marker laser beam 82 to the fluorescence of
such fluorescent slug is a function of the temperature of optical
fiber second end 26 and can be measured and used to calculate such
temperature. The optical fluorescent response, indicated by
reference numeral 94, is transmitted back through optical fiber 20
and out optical fiber first end 22 into optical bench 34. Optical
fluorescent response 94 preferably has extremely low power (in a
range of approximately 5-100 nanowatts) and has a preferred
wavelength of approximately 680-780 nanometers. Optical fluorescent
response 94 then passes through output lens 68 and output beam lens
assembly 66 to second beamsplitter 64. Second beamsplitter 64 is
constructed so that optical fluorescent response 94 is transmitted
therethrough to a signal filter set 96, which functions to block
any reflected marker and treatment light. The remaining signal,
filtered to pass only the fluorescent and blackbody wavelengths,
passes through a focussing lens 98 held together with the signal
filter set 96 in a signal optical assembly 99 onto a
fluorescence/blackbody detector 100. It will be understood that the
blackbody radiation returns along the same path as optical
fluorescent signal 94, but is passed in a fourth waveband through
second beamsplitter 64. Florescence/blackbody detector 100 thus
captures and analyzes this signal as a secondary temperature
mechanism for a fail-safe mode, where blackbody radiation
indicating a temperature too high for proper operation will shut
down power to the first laser diode.
[0018] It will be seen that a sensor board 102 is provided adjacent
to optical bench housing 60 so as to interface with
fluorescence/blackbody detector 100 and laser power detector 70.
Circuitry on sensor board 102 is connected to and communicates with
controller board 28 in order to calculate the temperature of
optical fiber second end 26. Optical bench housing 60 also serves
to cover optical bench 34 and keep stray light out. In the present
embodiment of the invention, black anodized 6061-T6 aluminum is
utilized for optical bench housing 60 to minimize reflection and
scattering of ambient light. It will be appreciated, however, that
optical bench housing 60 can be created from a reflective material
coated by an absorptive material, as it is not purposely placed in
a direct path with first laser beam 14.
[0019] In a preferred embodiment, a solenoid 36 is attached to
optical bench housing 60 and holds a mirror 38 at the end of a
shutter arm 40. It will be seen that solenoid 36 is able to actuate
shutter arm 40 to move mirror 38 into and out of the path of first
laser beam 14 after being passed by beam collimator 54. FIG. 3
depicts mirror 38 as being positioned outside the path of first
laser beam 14 during normal operation of laser treatment system 10,
thereby allowing laser light to pass into the rest of optical bench
34. While shutter arm 40 is shown as having been rotated
approximately 90.degree. from the position shown in FIG. 5, it will
be appreciated that solenoid 36 need rotate shutter arm 40 only an
amount necessary to move mirror 38 out of the path of first laser
beam 14. A position detection mechanism, identified generally by
reference numeral 42 (see FIG. 5), is provided to continually
monitor the position of shutter arm 40. More specifically, position
detection system 42 preferably includes a pair of Hall-effect
sensors 44 located near a magnet 46 placed on shutter arm 40. It
will be appreciated that Hall-effect sensors 44 sense the position
of mirror 38 and communicate the position thereof to main processor
30. In particular, only one of Hall-effect sensors 44 will sense
the presence of magnet 46 when mirror 38 deflects first laser beam
14 into beam dump 50 (i.e., the closed or blocked position) and
only the other of Hall-effect sensors 44 will sense the presence of
magnet 46 when mirror 38 permits first laser beam 14 to continue to
laser filter 74 (i.e., the open position).
[0020] It will be noted that laser filter 74 is preferably mounted
adjacent to mirror 38 in order to filter the sidebands of first
laser beam 14 (when permitted to pass thereto) so as to allow an
optimal wavelength of laser light to pass. At the same time, light
(identified by reference numeral 11 in FIG. 3) in wavelengths
slightly longer or shorter than the optimal wavelength are
preferably reflected into a beam dump 50 located adjacent to
optical bench 34 and attached to housing 60 thereof.
[0021] More specifically, beam dump 50 preferably includes a layer
51 of light absorbing material having an inverted cone shape and a
beam dump housing 52 (made out of aluminum, for example) encasing
absorber layer 51. The cone angle and light absorption of layer 51
enable beam dump 50 to contain nearly all of the light entering it
from an opening 55 therein oriented toward the inside of optical
bench 34. A transparent window 57 made of coated glass preferably
covers opening 55 in order to cause a seal within a cavity 65 of
beam dump 50, thereby assuring that out-gassing from absorber layer
51 will not deposit on the sensitive internal optics of optical
bench 34. Fins 59 are preferably placed on an exterior surface 61
of beam dump housing 52 so as to better dissipate heat therefrom.
In this way, it will be appreciated that heat contained within
absorber layer 51 is thermally conducted to beam dump housing 52
and to fins 59.
[0022] Absorber layer 51 preferably is a single material (e.g.,
carbon graphite) throughout beam dump 50 so that a light absorptive
surface is always present to capture any incoming light beam, even
if material on the surface of the conically-shaped depressions 63
is removed. This type of absorber layer 51 is advantageous over an
absorber comprising only an absorptive coating on a reflective
material, which scatters the laser light instead of capturing it
for conversion to heat energy when the coating is removed. Absorber
layer 51 preferably contains conically shaped depressions 63 which
are oriented so that the wider end is adjacent beam dump housing
opening 55 and faces toward the direction from which laser light
enters beam dump 50. Conically-shaped depression 63 are designed to
direct the extremely small amount of unabsorbed light into, rather
than out of, beam dump 50. All internal surfaces of absorber layer
51 are preferably absorptive, rather than reflective, to eliminate
backscattering of any light energy that enters absorber layer
51.
[0023] FIG. 3 shows that when laser treatment system 10 is
operational and first laser beam 14 is used, first laser beam 14
enters optical bench 34 via optical fiber 13 and travels through
lens 56 of beam collimator 54. When laser treatment system 10 is
operating without a detected error, as shown in FIG. 3, solenoid 36
holds mirror 38 out of the path of first laser beam 14 so that it
can proceed past mirror 38 to laser filter 74. As stated herein,
laser filter 74 blocks sideband wavelengths close to the
wavelengths of optical fluorescent response 94 emitted by the
fluorescent slug in optical fiber 20.
[0024] The portion of first laser beam 14 blocked by laser filter
74, indicated by reference numeral 11, is preferably reflected into
beam dump 50. Beam dump 50 is therefore placed near laser filter 74
to capture at least a portion of laser light reflected thereby. It
will be appreciated that laser light energy captured by beam dump
50 is converted to heat and moved away from the optics in optical
bench 34 to keep such optics cool. Removing rejected wavelengths of
treatment light from optical bench 34 also has the advantage of
keeping such light from first laser beam 14 away from
fluorescence/blackbody detector 100, whereby measurements using
information generated by fluorescence/blackbody detector 100 become
more accurate.
[0025] If main processor 30 on controller board 28 detects an
anomalous condition, it will preferably remove a signal holding
solenoid 36 open, thus causing mirror 38 to move into the path of
first laser beam 14. This is a fail-safe configuration since
solenoid 36 will divert first laser beam 14 to beam dump 50 by
default instead of allowing the light therefrom to pass through the
rest of optical bench 34. Alternatively, when no signal is required
to maintain solenoid 36 in an open position, main processor 30
could send a signal to solenoid 36 causing mirror 38 to move into
the path of first laser beam 14. In either case, first laser beam
14 will be reflected into beam dump 50. This position, with
solenoid-actuated mirror 38 in the path of first laser beam 14, is
shown in FIG. 5.
[0026] FIG. 5 depicts mirror 38 in the path of first laser beam 14.
It will be seen that first laser beam 14 is reflected from mirror
38 and passes through window 57 to absorber layer 51 in beam dump
50. Beam dump 50 then absorbs first laser beam 14, converts the
light energy thereof to heat energy, and dissipates the heat energy
away from the optics in optical bench housing 60. Absorber layer
51, made of a material with a high coefficient of heat transfer and
absorptive to light in the waveband of first laser beam 14 (e.g.,
carbon graphite), absorbs nearly all of the impinging light energy.
It will be appreciated, however, that any small portion of
reflected light energy travels to another highly absorptive surface
within absorber layer 51 because the angle of the conically shaped
depression 63 creates an angle of reflection that directs the
energy deeper therein. The thermal conductivity of absorber layer
51 then moves thermal energy through beam dump housing 52 to fins
59, where convection occurs to take the heat into the surrounding
air and away from optical bench 34. It will be understood that such
convection could be natural convection, utilizing the natural air
movements caused by temperature differences between fins 59 and
ambient air, or forced convection, caused by air moved by an
external source such as a fan. Window 57 serves to protect the
optical elements of optical bench 34 from debris or particles
created by impinging absorber layer 51 with laser light, as well as
acts in the capacity of a thermal insulator in helping to keep heat
away from optical bench 34.
[0027] It will be recognized that equivalent structures may be
substituted for the structures illustrated and described herein and
that the described embodiment of the invention is not the only
structure that may be employed to implement the claimed invention.
As one example of an equivalent structure that may be used to
implement the present invention, any cooling means may be
substituted for fins 59. For example, circulating water could be
used in place of the fins 59 to move heat away from beam dump
housing 52. However, the heat transfer abilities of absorber layer
51 and beam dump housing 52 allow the use of fins 59 in a medical
laser application where expense and close proximity of electronics
may proscribe the use of potentially leaky water cooling.
[0028] As a further example of an equivalent structure that may be
used to implement the present invention, any steering optics to
deflect first laser beam 14 into beam dump 50 could be substituted
for solenoid-activated mirror 38, such as a prism. Moreover, it
will be understood that the steering optics may automatically
deflect first laser beam 14 into beam dump 50 until it receives a
signal indicating normal operation of laser treatment system 10
from main processor 30. In this scenario, for example, mirror 38
will initially be positioned in the path of first laser beam 14 as
seen in FIG. 5. Once laser treatment system 10 is considered to be
operating normally, mirror 38 is removed from such path to permit
first laser beam 14 to enter optical fiber 20. It will also be
appreciated that one or more of the reflecting surfaces already
present within optical bench 34 may be rotated, removed or
otherwise repositioned so as to cause first laser beam 14 to be
deflected into beam dump 50 upon recognition of a specified
condition.
[0029] While preferred embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
invention. Accordingly, it is intended that the invention be
limited only by the spirit and scope of the appended claims.
* * * * *