AU673982B2 - Lights-pumped high power medical system - Google Patents

Description

OPI DATE 25/01/93 AOJP DATE 25/03/93 APPLN. ID 22551/92 PCT NUMBER PCT/US92/05456 111111 111111111 II I lilll AU9222551 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PAI bNI LCUrb IKAIUN IKl A I IrCT) (51) International Patent Classification 5 Iternational Publication Number: WO 93/00551 F21V 8/00 Al (43) International Publication Date: 7 January 1993 (07.01.93) (21) International Application Number: (22) International Filing Date: Priority data: 721,168 26June PCT/US92/05456 26 June 1992 (26.06.92) (81) Designated States: AU, BR, CA, JP, KR, RU, European patent (AT, BE, CH, DE, DK, ES, FR, GB, GR, IT, LU, MC, NL, SE).

Published With international search report.

Before the expiration of the time limit for amending the claims and to be republished in the event of the receipt of amendments.

991 (26.06.91) (71)(72) Applicant and Inventor: GHAFFARI, Shahriar [US/ US]; 8920 Business Park Dr., #250, Austin, TX 78759

(US).

(74) Agent: HAMILTON, Gary, Pravel, Gambrell, Hewitt Krieger, 1177 West Loop South, Suite 1010, Houston, TX 77027-9095 (US).

673982 (54)Title: LIGHTS-PUMPED HIGH POWER MEDICAL SYSTEM (57) Abstract The present invention provides a system which utilizes a conventional light source (10) to produce a narrowly focused beam of radiation having intensity similar to that produced by a laser. The system is broadly comprised of an omnidirectional light source (10) and an elliptical reflector with the physical parameters of the light source and the reflector being matched to produce a narrowly focused beam of intense radiation. The light produced by the system can be coupled into a fiber optic system (20) for delivery to the target area. In one embodiment of the invention, the dimension of the light source ar I the focal length of the reflector are chosen such that the focused beum can be easily accepted by a fiber optic (20) having an acceptance angle approximately equal to the inverse of twice the "F number" of the reflector.

WO 93/00551 PC/US92/05456 1 z LIGHTS-PUMPED HIGH POWER MEDICAL SYSTEM 3 Field of 4 the Invention The present invention relates to a system for use in 6 medical applications requiring light having high power 7 characteristics of lasers. More specifically, the present a invention provides a light source which is capable of 9 producing a beam of radiation having essentially the same beam intensity and spot size as a beam of radiation 11 produced by a laser.

12 Background 13 Lasers have a number of optical properties which make 14 them especially useful for a wide range of scientific, is industrial and medical applications. The two optical 16 characteristics most commonly associated with a beam of 17 laser radiation are "coherence" and "monochromaticity" of 18 the light beam. Other important characteristics of laser 19 light are a high level of beam intensity and the ability to focus the light team into a very small spot size. Although WO 93/00551 PCT/US92/05456 2 1 the properties of coherence and monochromaticity are z essential to certain applications, many of the applications 3 for which lasers are used do not require these qualities, but, rather, only require beam intensity and wavelengths of particular interest.

6 Laser systems are generally expensive to purchase and 7 operate and, thus, have not been available to many s potential users. Furthermore, in many of the applications 9 for which lasers are utilized, the expense of the system is borne to obtain the optical beam qualities, other than the 11 coherence and monochromaticity which are unique to lasers.

12 There is a need for an inexpensive optical system capable 13 of providing an intense beam which is capable of being 14 focused into a small area.

is A prior art lamp-based laser simulator is shown in 16 U.S. Patent No. 4,860,172 issued to Schlager et al. In the 17 system disclosed by Schlager, light from an omnidirectional 18 conventional light source is collected and focused with 19 conventional means into an optical coupling cone which is intended to condense the conventionally focused beam for 21 launching into a fiber optic cable.

22 Although the stated goal of the '172 patent is to 23 provide a light source having many of the characteristics 24 of laser light, the optical parameters of the system 2s disclosed in the '172 patent are not capable of producing 26 laser-simulated light at an intensity suitable for 7 'ost 27 medical applications. There are three parameters which WO 93 00551 W CT/US92/05456 3 I must be optimized to produce light having a high intensity 2 and small spot size using the optical components shown in 3 the '172 patent: 1) the gap spacing between the electrodes, 4 2) the magnification of the reflector, and 3) the s acceptance angle or numerical aperture of the optical 6 fiber. Larger lamp gap sizes tend to result in higher 7 power output. Large gap sizes, however, also tend to 8 result in larger spot sizes due to the magnification 9 properties of the reflector. The acceptance angle of a fiber optic dictates the maximum spot size on the cone at a 11 given entrance angle which can be completely coupled into 12 the fiber. The acceptance angle is related to the 13 numerical aperture of the optic fiber by the following 14 equation: Is sin (acceptance angle) numeric aperture.

16 There is a need, therefore, to match the gap size and the 17 magnification of the reflector to produce a beam which can 18 be accepted by the optical fiber for delivery to the 19 tissue. The system of the '172 patent attempts to optimize the coupling of light into the fiber optic through the use 21 of a cone. More specifically, the '172 patent suggests a that light can be coupled into a fiber optic via a cone 23 which reduces the spot size.

24 Although the cone shown in the '172 patent will as produce a smaller spot size, the beam delivered power will 26 actually be reduced because of the inherent optical 27 properties of the coupling cone and the optical fiber. The WO 93/00551 PCT/US92/05456 4 1 -entrance of cone has an acceptance angle which determines 2 the first numerical aperture of the cone. Likewise, the 3 cone exit has an output numerical numerical aperture which 4 actually increases as the output beam spot size is reduced.

s The increased numerical aperture of the cone exit will 6 cause significant divergence in the exit beam. The 7 divergence of the beam from the cone exit results in an 8 optical loss because a significant portion of the energy 9 which exits from the cone may not meet the acceptance criteria of the numerical aperture of the fiber optic. The 11 net result is a beam which does not have sufficient power 12 to provide the beam intensity needed for many medical 13 applications.

The present invention provides a system for producing an intense beam of light having a small spot size for delivery to a portion of tissue, comprising: a radiation source; a first reflector means having first and second focal points, said radiation source being placed at said first focal point, said first reflector means being operable to direct radiation from said radiation source towards said second focal point; optical means for limiting radiation received at said second focal point to a specific numerical aperture; optical receiving means at said optical receiving means having a numerical aperture to accept said radiation passed by said means for limiting said radiation received at said second focal point; and means for delivering radiation from said optical receiving means to a portion of tissue.

The second mirrored surface has an aperture therein which is placed at a point near the second focal point of the first reflector. The light source is placed at the first focal point of the reflector and the accepting end of a fibre optic is placed at the second focal point of the reflector. The aperture is positioned 25such that only rays meeting predetermined geometrical exit criteria can pass through the aperture and be accepted by the fibre optic located at the second focal point. Those rays which do not meet the exit criteria are reflected by the mirrored surface toward the interior of the cavity.

Some of the reflected rays provide additional 30 amplification of the light produced by the light source and the path of these rays is altered such that they are ventually able to meet the exit criteria and pass through •the aperture.

The light produced by the system can be coupled into a WO 93/00551 PCT/US92/05456 6 1 fiber optic system for delivery to a target area. The 2 dimension of the light source and the focal length of the 3 reflectors in the optical cavity are chosen such that the 4 focused beam can be easily accepted by a fiber optic having a numerical aperture approximately equal to the inverse of 6 two times the "F/number" of the reflector.

WO 93/00551 PCT/US92/05456 7 1 Brief Description 2 of the Drawings 3 A better understanding of the present invention can be 4 obtained when the following detailed description of the preferred embodiment is considered in conjunction with the 6 following drawings, in which: 7 FIG. 1 is an elevational side view of the optical a system of the present invention showing the light source 9 positioned in an optical cavity comprising a first curved reflector and a second reflector.

11 FIG. la is an elevational side view of the optical 12 system of the present invention showing a curved second 13 reflector for redirecting light into the optical cavity.

14 FIG. 2 is an illustration of the geometry of the focused light rays arriving at the second focal point of 16 the reflector.

17 FIG. 3 is an elevational side view of the optical a1 system of the present invention showing the electrode gap 19 in the light source.

FIG. 4 is a graphical illustration of a conventional z2 continuous wave power level and the pulsed power levels 22 employed in the system of the present invention.

23 FIG. 5 is an elevational view in cross section of the 24 optical delivery system of the present invention.

FIG. 6 is an illustration of a focussed beam of 26 radiation delivered by the system of the present invention.

PCT/US92/05456 WO 93/00551 8 1 FIG. 7 is a graphical illustration of the wavelengths 2 of light produced by an arc lamp.

WO 93/00551 PCT/US92/05456 9 1 Detailed Description of 2 the Preferred Embodiment 3 Referring to FIG. 1, the optical system of the present 4 invention is shown in its preferred embodiment. The system s comprises a light source 10 which is mounted in an optical 6 cavity comprising a first curved reflector 12 and a second 7 reflector 14 which can be either curved or flat. Light 8 produced by the cavity is carried by a fiber optic 20 to a 9 delivery system 24, discussed in greater detail below. The embodiment of the invention illustrated in FIG. l comprises 11 a second reflector 14 which is flat. The alternate 12 embodiment of the optical cavity, shown in FIG. la, 13 comprises a curved second reflector 14a.

14 The light source 10 used in the present invention is a is conventional light source in the form of an a: z lamp. The 16 arc lamp comprises a cathode 16 and an anode 18 which are 17 connected to an appropriate power source and mounted in a 18 quartz housing 19. The interior of the housing 19 is 19 filled with a gas or vapor which produces light when 2o excited by an electric current flowing between the cathode 21 16 and the anode 18. In the arc lamp used in the preferred 22 embodiment of the present invention is a Xenon-Mercury 23 vapor.

24 When the lamp is energized, the cathode 16 passes electrons which are accelerated toward the anode 18. The 26 collision of the electrons with the Xenon or Mercury atoms 27 causes the electrons orbiting those atoms to move to a WO 93/00551 PCT/US92/05456 I higher energy levels or "stimulated states." When the 2 excited electrons return to their normal energy levels, 3 they emit photons which have a wavelength determined by the 4 difference between the energy levels of the excited state s and the normal state.

6 FIG. 1 illustrates a plurality of light rays produced 7 by the light source 10. The rays 22a-22b and 22a'-22b' a originate at the theoretical center of the first focal 9 point of the reflector 12 are all reflected toward the second focal point of the reflector 12 and can be coupled 11 into the fiber optic 20 after passing through the aperture 12 in the second reflector 14. Other rays originate at points 13 between the cathode 16 and anode 18, as illustrated by rays 14 22c and 22c', respectively. These rays are also reflected s1 by the reflector 12, but fail to pass through the aperture 16 13 in the second reflector 14 and, therefore, are reflected 17 by the mirrored surface of the reflector 14 back toward the s1 interior of the cavity, as discussed in greater detail 19 below. Some rays, such as the one illustrated by reference numeral 22d are not reflected by the first reflector 12 and 21 thus exit the reflector cavity.

22 The light rays which are focussed at the second focal 23 point can be accepted by the optical fiber 20, provided 24 certain constraints are met. In general, the limiting factors are the size and acceptance angle of the optical 26 fiber, the size of the gap of the light source 10 at the 27 first focal point of the reflector 12 and the magnification WO 93/00551 PCT/US92/05456 11 I of the reflector 12.

2 As a general principle, the gap size of the light 3 source is directly correlated with the amount of 4 electromagnetic radiation produced with larger gap sizes producing greater power. The size of the gap, however, 6 also has an impact on the ability to converge the light 7 rays for efficient entry into the fiber optic. As s discussed above, FIG. 1 includes an illustration of light 9 rays produced from different portions of the gap between the cathode 14 and the anode 16 of the arc lamp used in the 11 preferred embodiment of the invention. Since the rays 12 originate from a band of points, rather than from the 13 theoretical focal point of the reflector, the group of rays 14 focused at the second focal point will also arrive in a is band defined by the geometry of the reflector. This 16 geometry of the arriving rays is shown in FIG. 2, which 17 shows a band of arriving rays passing through the aperture a1 having a width of In the case where the band width of 19 the rays reflected by the curved reflector 12 and passing through the aperture corresponds to the acceptance angle of 21 the fiber optic, there will be effective coupling into the z fiber optic. However, in the case where the band width of 3 the focussed rays exceds the acceptance angle of the fiber 24 optic, there will be inefficient coupling of the light into the fiber optic. The bands of incident rays illustrated by 26 reference numerals 23 and 23' in FIG. 2 do not match the 27 numerical aperture of the fiber optic and, therefore, would WO 93/00551 1 CT/US92/05456 12 1 result in inefficient coupling. In the present invention, 2 these rays are reflected by t mirrored inner surface of 3 the second reflector 14 and, furthermore, the geometric 4 parameters of the optical cavity prevent these rays from s exiting until the criteria for efficient coupling have been 6 met.

7 If all of the surfaces in the cavity were perfectly 8 reflective and had perfect geometry, the returned rays 9 would be caught in a "reflective loop." However, a number of factors prevent this phenomenon. The rays which are 11 returned by the reflector 14 are re-reflected by the first 12 curved reflector 12 will be directed to the interior of the 13 cqartz housing of the arc lamp. Upon passing through the 14 quartz, these rays will be refracted slightly. This will is change the direction of the rays as illustrated in FIG. la, 16 thus preventing them from being caught in a reflective 7 loop. Moreover, the additional light returned from the 18 reflective surface will add to the new light being 19 generated in the arc gap between which will result in a certain degree of amplification of the light produced by 21 the arc lamp. The amount of amplification is determined by 22 the reflectivity of the reflectors and the absorption a characteristics of the various media within the cavity.

24 The reflective loop phenomenon can also be avoided by 2s controlling the position of the second reflective surface 26 with respect to the focal point of the first reflector.

27 Also, a curved second reflector, suwh as that shown in FIG.

WO 93/00551 PCT/US92/05456 13 1 la, can be used to minimize reflective loops, thus 2 improving the output light generation efficiency.

FIG. la is an illustration of an alternate embodiment 4 of the present invention utilizing a curved reflector 14' s having a mirrored inner surface. The curved reflector 14' 6 includes an aperture 13' passing light rays meeting the 7 acceptance criteria of the acceptance angle of the fiber 8 optic 20. In this embodiment of the system, those r'ys 9 which meet the exit criteria, e.g. ray 36, of the cavity are allowed to pass through the aperture 13'. However, 11 those rays, e.g. ray 38, will be reflected back into the 12 interior of the cavity where they will be again reflected 13 by the reflective surface of the elliptical reflector 12.

14 In the present invention, the arc lamp 10 is pulsed to is power levels several times higher than normally used for 16 continuous wave (CW) operation of the lamp. This pulsed 17 operation has the effect of creating very intense 18 production of light. Referring to FIG. 3, a small sphere 19 of plasma 15 production is shown at the tip of the cathode 16 of the arc lamp. This plasma is caused by very intense 21 bombardment of electrons emerging from the tip of the 22 cathode 18. This plasma region normally exists near the 23 tip of the cathode when the lamp is operating in the CW 24 mode. In the present invention, however, the pulsed operation of the lamp will cause the plasma region to 26 temporarily expand to span the entire distance between the 27 electrodes, as illustrated by the plasma region 15' shown WO 93/00551 PCT/US92/05456 14 1 in FIG. 3.

2 FIG. 4 is a graphical illustration of the power levels 3 used in the present invention to create the pulsed plasma 4 effects discussed above. The power levels discussed herein are for a Mercury-Xenon lamp; however, the principles of 6 pulsed operation can be applied to other types of lamps to 7 obtain similar results. The normal CW power level shown in a FIG. 4 is approximately 28 amps, 1000 watts of power 9 consumption. Using the pulsed method, however, the current is increased to more than 50 amps for brief periods of 11 time, on the order of 1 to 10 milliseconds, resulting 12 in delivered electrical power in excess of 2,500 watts.

13 Indeed, it is possible to increase the power to even higher 14 levels for even shorter periods of time. For example, the is lamp is capable of sustaining 100 amps for periods of time 16 on the order of 100-500 microseconds.

17 The pulsed operation of the arc lamp used in the la present invention produces the intense plasma region 19 between the two electrodes, as discussed above, thus making it possible to obtain beam intensities at very small spot 21 sizes which are very similar to those produced by 22 conventional lasers.

23 The various embodiments of the present invention, the 24 curved reflector 12 has an elliptical geometry. However, other geometries known to those skilled in the art can be 26 used. For example, a parabolic reflector with an 27 appropriate lens system could be used to obtain focussing WO 93/00551 PCT'/US92/05456 1 properties similar to that obtained with the elliptical.

2 reflector used in the preferred embodiment. The 3 magnification of the elliptical reflector 12 is determined 4 by the distance between the focal points and the size of s the ellipse. The light source 10 is placed at one of the 6 first focal point of the reflector and an optical fiber 7 is placed at a second focal point of the reflector.

a The delivery system of the present invention, shown in 9 FIG. 5, is comprised of two lenses configured in a 4-f arrangement. The delivery system comprises a housing 11 with an optic terminator 42 secured in one end thereof. The 12 terminator delivers light from the fiber optic 20 to a first 13 diverging lens 44 to produce a collimated light beam. The 14 collimated light beam is passed through an appropriate filter 46, discussed in greater detail below, and is UI received by a converging lens 48 for focussing the light 17 radiation on the tissue to be treated. The filter is placed ia in the light path to control the wavelengths being delivered 19 to the ablation or coagulation site. In order to reduce the tolerances on the filters, the position of the filter is 21 chosen in the delivery system between the two lenses. The' 22 filtering operation may be chosen by sliding a filter into a 23 slot in the delivery system. Two grated index GRIN fiber 24 lenses cai aplace the normal lenses as presented, as long as as both of them have good transmission in the UV and visible 26 wavelengths. A conical tip 50, discussed in greater detail 27 below, assists in the precise delivery of the light to a WO 93/00551 PCT/US92/05456 16 1 desired location on the tissue.

2 The advantage of a 4-f configuration is that the fiber 3 optic output light is focussed into a smaller spot at a I given wavelength. In the present invention, the advantage of using this lens arrangement is that the UV wavelengths 6 are focussed into a small spot closer to the 2Nd lens than 7 the visible wavelengths (due to Chromatic aberrations).

a The conical tip 50 is used as a guide to indicate the 9 best focussing point for optimized cutting action. FIG. 6 is an illustration of the concentric cones of .radiation 11 which result from the light being focused by the 4-f lense 12 system. The UV light creates an ablation sight which is 13 shown touching the surface of the tissue in FIG. 6. The 14 visible wavelengths are focussed to just below the ablation plane of the delivery system which cause coagulation of the 16 underlying blood vessels before the ablation front reaches 17 these layers.

ia Typical spectra for Mercury and Xenon lamps are shown 19 in FIG 7. The Mercury lamp has several peaks in UV and visible ranges as opposed to the Xenon lamp which has a more 21 continuous spectrum. Mercury-Xenon lamps have 22 characteristics very similar to the Mercury with a small 23 additional Xenon baseline.

24 The Mercury lamp spectrum peaks at 404, 430, 546 and 2s 579 are very close to the peaks of the absorption 26 characteristic of blood. Tissue, on the other hand, has low 27 absorption characteristic in the visible, increasing in WO 93/00551 PCT/US92/05456 17 1 excess of 100 cm-1 in the UV wavelengths below 320 rm.

2 Presently, Excimer lasers at 351 and 308 nm have shown very 3 good cutting action with minimal damage to the surrounding 4 tissue about the ablation site. The minimum thermal damage is partially due to the short pulse widths and photo- 6 ablation effects of the UV Excimer wavelengths.

7 If only an Excimer laser is used for tissue cutting, s the tissue will bleed since the blood vessels are not 9 coagulated to stop the blood flow. Blood coagulation could be promoted by using a dye laser tune-d at the wavelength of 11 high blood absorption, but with much lower tissue absorption 12 in which the arget of coagulation is the blood and not the 13 normal tissue. Consequently, an optimized scalpel may be 14 based on using multiple wavelengths such as UV for cutting and wavelengths around 420, 546 and 577 where the relative 16 blood absorption is higher than other wavelengths. The 17 Mercury lamp (or Mercury Xenon lamp) has the proper sl characteristic to match the needed multi-spectral 19 characteristics as discussed above.

The system of the present invention can be operated in 21 a pulsed mode, as discussed above, to produce ablation of a 2 site using pulse durations on the order of a few 23 milliseconds. The short pulse width results in minimal 24 thermal damage to the tissue.

The present int ition may be used for cutting tissue if 26 all available wavelengths are focussed at the tip of the 27 delivery system. In order to cauterize or coagulate blood, WO 93/00551 PCrT/US92/05456 18 I the wavelengths in the visible range and of particular 2 interest the peaks of 546 and 577 nm can be delivered to the 3 tip with other wavelengths being filtered out by inserting 4 an appropriate filter into the delivery system.

Several different wavelengths of lasers from argon (488 6 and 514 nm) and YAG (1064 nm) and C02 (10,600 nm) have been 7 used for tissue welding. The main goal in tissue welding is 8 to heat the junction of the two sections of tissue (held 9 against each other) to reach temperatures just below their i0 coagulation point resulting in melting of the collagen of 11 tissue together. The melting of the collagen promotes 12 better and faster tissue healing of the junction.

13 The present invention is capable of generating a beam 14 having wavelength components which can penetrate into tissue is to depths of several millimeters. Consequently, if the 16 system is configured to operate in a continuous wave mode, 17 rather than pulsed mode, the continuous low level light can 18 produce sufficient heating of tissue to allow the present 19 invention to be used for tissue welding as well. A temperature monitoring system can be incorporated in the 21 delivery system to provide more accurate tissue heat zz generation thereby avoiding over-exposure of the tissue 23 while allowing more homogeneous welding process.

24 In normal surgery, it is usually important to use a cutting device to penetrate into the tissue or body. The 26 present invention can be used to ablate tissue and cut 27 through different layers of skin. The delivery system is WO 93/00551 PCT/US92/05456 19 1 placed against the ablation site and the light source is 2 activated to produce high power pulses of light. The 3 generated light causes tissue ablation and the operator can 4 move the delivery system along the desired cutting pattern on the skin. A complete penetration through skin normally 6 requires several passes of tissue removal with a careful 7 inspection of the ablation site.

8 The present invention also can be used to cauterize 9 blood quickly. The cauterizing filter is place in the optical path and the system is activated while the delivery 11 system is pointed toward the bleeding site. This technique 12 can be used to coagulate blcnd vessels under skin in depths 13 down to 0.6 millimeters as well.

14 When the operation is completed the cut size is closed is using a few conventional sutures. The system can then be 16 configured to operate in the welding mode whereby a 17 continuous low level light is produced. Upon activation, is the delivery system produces mild heating of the closed cut 19 area as it is moved along the cut path. The rate of zo movement and the heat generated can be calibrated by either 21 a heat sensing fee iback system or the experience of the 22 operator. Normal junction temperatures in the 60-85 OC 23 produces the desired effect.

24 Although the present invent' n has been described in connection with the preferred embodiment, it is not 26 intended to be limited to the specific form set forth 27 herein but, on the contrary, it is intended to include such WO 93/00551 PMU'S92/05456 modifications, alternatives and equivalents as may reasonably be included with the scope of the invention as defined by the appended claims.

Claims (19)

1. A system for producing an intense beam of light having a small spot size for delivery to a portion of tissue, comprising: a radiation source; a first reflector means having first and second focal points, said radiation source being placed at said first focal point, said first reflector means being operable to direct radiation from said radiation source towards said second focal point; optical means for limiting radiation received at said second focal point to a specific numerical aperture; optical receiving means at said optical receiving means having a numerical aperture to accept said radiation passed by said means for limiting said radiation received at said second focal point; and means for delivering radiation from said optical receiving means to a portion of tissue.

2. The system of Claim 1 wherein said means for producing radiation comprises a conventional light source.

3. The system of Claim 2, wherein said light source is an arc lamp having first and second electrodes with a gap therebetween.

4. The system of Claim 3, wherein said light source is provided with pulsed power to cause intense pulses of light to be produced between said electrodes.

5. The system of Claim 4, wherein said power is pulsed for a period of between one and ten milliseconds.

6. The system of Claim 5, wherein said means for 30 limiting radiation received at said second focal point comprises a reflective surface having an aperture therein, said aperture allowing rays meeting a predetermined numerical aperture criteria to be passed therethrough, with rays not meeting said numerical aperture criteria being redirected toward said first reflector.

7. The system of Claim 6, wherein said means for delivery said radiation comprises a fibre optic. djj -IT 22

8. The system of claim 7 wherein said means for delivering said radiation further comprises means operably coupled to said fibre optic to receive radiation passed therethrough and to focus said radiation on a portion of said tissue.

9. The system of claim 8 wherein said means for delivering said radiation further comprises filtering means for controlling the wavelength of radiation focused on said tissue.

The system of claim 9 wherein said arc lamp comprises a Mercury-Xenon vapour, said radiation produced by said lamp comprising light at wavelengths corresponding to ultraviolet, visible and infrared.

11. A system for producing an intense beam of light having a small spot size for delivery to a potion of tissue comprising: a radiaticn source; 15 a first reflector means having first and second focal points, said radiation source being placed at said first focal point, said e first reflector means being operable to direct radiation from said radiation source towards said second focal point; optical means for limiting radiation received at said second focal point to a specific numerical aperture; optical receiving means at said second focal point, said optical receiving means having a numerical aperture matched to the numerical aperture of said first reflector means; and I L -v: 22A means for delivering radiation from said optical receiving means to a portion of tissue.

12. The system of Claim 11 wherein said means for delivering said radiation comprises a fibre optic.

13. The system of Claim 12 wherein said means for delivering said radiation further comprises means operably coupled to said fibre optic to receive radiation passed therethrough and to focus said radiation on a portion of said tissue.

14. The system of Claim 13 wherein said means for delivering said radiation further comprises filtering I aS. means for controlling the wavelength of radiation focused on said tissue.

A system for producing an intense beam of light having a small spot size for delivery to a portion of tissue comprising: a radiation source; a first reflector means having first and second focal points, said radiation source being placed at said first focal point, said first reflector means being operable to direct radiation from said radiation source towards said second focal point; optical means for limiting radiation received at said second focal point to a specific numerical aperture; fibre optic means for receiving said radiation at said second focal point and delivering said radiation to a portion of tissue, said fibre optic means having a numerical aperture to accept said radiation passed by said means for limiting said radiation received at said second focal point.

16. The system of Claim 15, wherein said means for limiting radiation received at said second focal point comprises a reflective surface having an aperture therein, S^ said aperture allowing rays meeting a predetermined numerical aperture criteria to be passed therethrough, 25 with rays not meeting said numerical aperture criteria S' being redirected toward said first reflector.

17. The system of Claim 16, further comprising focusing means operably coupled to said fibre optical to receive radiation passed therethrough and to focus said 30 radiation on a portion of said tissue.

18. The system of Claim 17, wherein said means for delivering said radiation further comprises filtering means for controlling the wavelength of radiation focused on said tissue.

19. The system of Claim 18, wherein said arc lamp comprises a Mercury-Xenon vapour, said radiation produced by said lamp comprising light at wavelength corresponding to ultraviolet visible and infrared. DATED this Seventh day of November 1995. SHAHRIAR GHAFFAIR By his Patent Attorneys GRANT ADAMS COMPANY tu1*11 I 4 I I a II I.. 4 4 4 4* 4 4 a a a. ~A Lq '1- 0