CA2096100A1

CA2096100A1 - Linear scan method and system for energizing an optical fiber bundle

Info

Publication number: CA2096100A1
Application number: CA002096100A
Authority: CA
Inventors: Kenneth P. Grace
Original assignee: Spectranetics LLC
Current assignee: Spectranetics LLC
Priority date: 1992-05-13
Filing date: 1993-05-12
Publication date: 1993-11-14
Also published as: JPH0638975A; EP0574686A2; US5400428A; EP0574686A3

Abstract

ABSTRACT OF THE DISCLOSURE

A method and apparatus for relatively moving energy across an array of optical fibers.
The energy may be scanned across the fiber array.
A dielectric mirror mounted on a galvanometer scanner is moved so as to cause successive pulses to irradiate different segments of the fiber optic array. As a result, each fiber receives radiation having sufficient fluence while reducing the energy per pulse (or the cw equivalent). Rather, than move the energy across the fiber array, the fiber array itself may be moved. One possible manner of movement is use of a piezo electric stack.

Description

~ C 9 ~ ~ 0 LINEAR SCAN METHOD AND SYSTEM FOR EN~RGIZING
AN OPTICA~ FIBER BUNVL~

CROS~ REFERENCE TO ~LA~ APP~ICATTONS

The subject matter of this application relates to U.S. Patent Applicatio ~
07/417,245 issued a~ U.S. Paten ~ 6,9 ~ ~, entitled "Optical Fiber Coupler With LinearG~
Input", the subject matter of which i~
incorporated herein by reference. 6/~

BACKGROUND OF THE INVENTION

1. Field of the Invention:
This invention relates to a method and apparatus for linearly scanning an energy source over an array of optical fibers. More particularly, the present invention allows a series of energy pulses to be directed into different predetermined linearly-arranged segments of the optical fiber array.

2. ,DescEi~tion of the Prior Art:
The use of radiant energy sources, such as lasers, in medical procedures is presently attracting great attention. For several decades, scientists have described the use of lasers to ablate tissue. Suggested applications have included removing hair, corneal surgery, removing port wine stain and removing plaque from blood vessels. For example, percutaneous transl~minal laser angioplasty involves the introduction of a catheter containing a bundle of optical fibers, into a blood vessel. The distal end of the catheter is positioned next to an obstruction in the blood vessel. Laser energy is applied to the .'`'.
, , xcs6~no optical fibers to ablate the obstruction. To be effective, each fiber in the bundle must carry laser energy having sufficient fluence (energy per unit area) to ablate tissue. Furthermore, laser surgeons have recognized the desirability of removing as large an area of the obstruction as possible without excessive manipulation of the catheter. This calls for a large number of optical fiber~ within the catheter. When laser radiation with a sufficiently high fluence is applied to a number of fibers simultaneously, a large amount of laser energy is introduced into the body. The body is traumatized by such energy.
In fact healthy tissue can easily be damaged. At the same time, a large and costly laser is required to produce the large amount of energy.
Prior to this invention the seemingly contradictory goals of applying laser radiation of sufficient fluence over a relatively large area, while at the same time reducing the peak total energy applied to the body had not been realized.
~ U.S. Paten ~ to Kittrell et al.
: ~ 6 I B teaches a laser angioplasty system including acatheter housing a bundle of optical fibers. The ~ 225 multiple fibers allow the selection of tissue to 5/o o be removed. Selectivity is achieved by monitoring ~/0 0 spectroscopic characteristics. Each fiber of the bundle may be arranged in a linear array. Either the array or the laser energy is movable to allow each individual fiber to be selectively irradiated. First, low level energy is applied to each individual fiber in seqiuence and reflections from tissue proximate the distal end of the fiber are monitored to distinguish healthy tissue from tissue to be ablated. Then, high fluence laser energy is sequentially applied to one fiber at a time and only to those fibers illuminating tissue - . , .

2~96100 to be ablated. Nowhere in this patent is there --any suggestion of the desirability or even the possibility of grouping more than one of the optical fibers making up the array for simultaneous irradiation. In fact, such an arrangement would destroy the fundamental function and purpose of the system described in the patent.
U.S. Patent 4,614,868 to Alster teaches an imaging system in which a lasèr beam can be scanned over a fiber optic bundle by irradiating fibers singly or in groups of fibers, the groups being as large as the spot size of the laser beam.
However, this patent fails to suggest that scanning a laser beam, having sufficient fluence to ablate tissue, over a linear array of optical fibers is advantageous in reducing the total energy delivered or in reducing the size of the laser required.
U.S. Patent 4,007,377 to Simon. et al.
discloses an optical scanning system for use with universal product codes. A series of optical components, including a galvanometer, is used to expand the laser beam to illuminate an entire bar code. There is no suggestion of how a scanning system may be employed to maintain a sufficiently high fluence yet reduce energy in an ablation system.
Hotchkiss discloses, in U.S. Patent 3,984,171, a linear scan system that provides a vertically and horizontally defined continuous linear scan of predetermined length. Even though Hotchkiss discloses a device that appears to be able to scan in a linear manner, there is certainly no suggestion to irradiate selected groups of optical fibers sequentially.
U.S. Patent 4,838,631 to Chande teaches a laser beam directing system for directing - , - ,. .

successive beam pulses of a pulsed laser into different optical fibers. This invention is especially useful with laser systems used in manufacturing and especially for use where a single laser is shared between several manufacturing workstations. There is no teaching that the device has any use in the medical field.
This patent fails to suggest that scanning a laser beam, having a sufficient fluence to ablate tissue, over a linear array of optical fibers is advantageous in reducing the total energy delivered or in reducing the size of the laser required.

SUMMARY OF THE INVENTION

The present invention is directed at a more efficient apparatus and method of deli~ering energy to an optical fiber array. The optical fibers of the array are arranged to enable an energy source to sequentially irradiate different groups of fibers in the course of linear relative movement between the fibers and the energy. The present invention is extremely useful in medical applications, as the invention allows less energy per pulse (or the energy per unit time for a continuous wave (cw) energy source) to be delivered to a patient and the use of a less powerful energy source. In the present invention, not all of the optical fiber array is irradiated at one time. Therefore, the total energy per pulse (or the cw equivalent) delivered to the patient can be reduced. The irradiated portion of the optical fiber array, while still maintaining a fluence level in each fiber of the portion sufficient to ablate tissue, receives and transmits less energy per pulse to the tissue upon - " ~

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which surgery i5 being performed than if all fibers in the array are irradiated simultaneously, thus reducing the risk of in~ury to the patient.
In medical applications, the system alleviates much o~ the concern involved with delivering large quantities of energy to human tissue in a single pulse.
The present invention relies upon nmultiplex coupling" to couple energy to an array of optical fibers. Because not all the fibers in the array are irradiated simultaneously, the fiber area used in the fluence calculation is smaller.
To compensate for the decrease in area, the energy per pulse can be reduced, thus yielding the same fluence as when all fibers are irradiated at a higher energy per pulse. In this manner, less laser energy per pulse is delivered to the patient.
Although the present invention is applicable for use with a wide array of energy sources, the preferred embodiment uses a linearly focused laser beam to provide a substantially uniform distribution of energy over the optical fiber portion that is irradiated. That is, all fibers in the portion experience the same modal excitation as a result of using the linearly focused laser beam.
According to the preferred embodiment of the present invention, portions of a fiber array are sequentially irradiated with each laser pulse.
That is, the laser beam can be linearly scanned across the array and irradiate 1/4, 1/3 or 1/2 of the optical fibers of the array in each pulse. Of ; course, the fraction of the optical fibers is not limited to 1/4, 1/3 or 1/2, but may be any fraction so long as the number of fibers illuminated is greater than one but less than the total number of fibers.

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One embodiment of the array includes a single row of optical fibers. As described above, the incident laser beam m~y irradiate 1/2, 1/3, 1/4, etc. of the fibers with successive pulses.
S The array may be more than a single row of optical fibers. For example, the array could be two parallel rows of optical fibers. Either sequential portions o~ both rows of fibers can be illuminated or either the first row and then the second row can be illuminated by the laser light.
Another possible array configuratlon i8 to have a plurality of bundled fibers, where each bundle iB the same size, disposed along a common transverse axis. Each bundles is composed of more than one optical fiber. Further, each bundle makes up, for example, 1/2, 1/3, 1/4, etc. of the total number of optical fibers. The present invention operates by irradiating successive bundles of fibers.
As the present invention only illuminates a fraction of a fiber array with each pulse of energy, the invention thus allows for a reduction in the energy per pulse (or the cw equivalent) delivered to a patient and a reduction in the size of the energy source. Hence, it is an object of the present invention to reduce the energy per pulse (or the cw equivalent) and size of the energy source by providing a linear optical scan ~y~tem for an energy source.
Furthermore, the present invention may employ a quick coupling system particularly suited to the scanning arrangement of the present invention.

- ., 2C96~0 BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and characteristics of the present invention, as well as the methods of operation and function of the related elements, will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification. In the drawings, like reference numerals designate corresponding parts in the various figures, of which:
FIGURE 1 is a schematic diagram of one embodiment of the present invention;
FIGURE 2 is an enlar~ed view of a fiber bundle across which the laser beam is scanned;
FIGURE 3a i8 an enlarged view of a second embodiment of the fiber array in a first scan position;
FIGURE 3b is an enlarged view of the second embodiment in a second scan position;
FIGURE 4 depicts apparatus for implementing the scanning in FIGURES 3a and 3b;
FIGURE 5a depicts another embodiment of the fiber array;
FIGURE Sb shows yet another embodiment of the fiber array used in conjunction with the present invention;
FIGURE 6 illustrates the present invention utilized in a laser catheter;
FIGURE 7 schematically illustrates control apparatus of the scanners pictured in FIGURES 1 and 4;
FIGURES 8a and 8b illustrate a perspective and front view of the male coupler according to the present invention;

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' , . ' . ' . . ' FIGURES 9a-9o illustrate the process for positioning fiber bundles into grooves;
FIGURE 10 illustrates an optical fiber coupler including a male coupling portion and a female coupling portion particularly suited for use with the present invention; and FIGURE 11 illustrates the same device as pictured in FIGURE 10, with the male and female coupling portions separated.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED
EXEMPLARY EMBODIMENTS

FIGURE 1 is a schematic diagram of the present invention. Energy, such as laser beam 10, preferably produced by an excimer laser, is focused by a lens system so as to be linear in cross section. The laser and optics assembly is shown generally at 70 and is described in detail in U.S. Patent 5,016,964. Of course, laser beam 10 could be produced by a laser other than an excimer laser. In fact, the energy could be generated by a source other than a laser.
The linearly focused beam 10 enters focusing/guiding apparatus 14 at position 11 and is incident on dielectric mirror 13 disposed on scanner 12. The exact dielectric coating used to form mirror 13 varies depending on the laser radiation employed. That is, the dielectric mirror 13 is chosen so as to optimize reflection for the particular wavelength of laser energy that is employed. Scanner 12 is preferably a stepper motor that moves mirror 13 between positions.
Alternatively, scanner 12 may be a galvanometer or a linear translator driven by a motor, cam or piezo crystal stack. A galvanometer may provide improved accu~acy and scanning speed.

. , . ~ : . :

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2C961{)0 Scanner 12 rotates mirror 13 as indicated by arrow 15. Although arrow 15 appears to indicate significant deflection, the amount mirror 13 i8 deflected is in reality very minute. The deflection of mirror 13 is only enough to scan laser beam 10 over fiber optic array 20. Scanner 12 moves laser beam 10 in the direction indicated by arrow 21. It is equally possible to move the fiber array rather than laser beam. Such a sy~tem will be discussed with reference to FIGURE 4.
Optical elements 16 and 18 are interposed in apparatus 14 between scanner 12 and array 20.
Elements 16 and 18 may be devices such as lensec or filters. Lenses are used to adjust the size of the linearly focused beam 10.
The normal or rest position of beam 10 is indicated by reference numeral 28 in FIGURES 1 and 2. That is, if the laser beam was not scanned over fiberoptic array 20, beam 10 would land on and irradiate position 28. Side sections 25 and 27 are juxtaposed to normal position 28 of beam ~0. Fiber array 20 may thus be broken into three distinct sections when beam 10 is not being scanned thereacross. These sections are the normal position 28 of beam 10 and the two side sections 25 and 27.
A first embodiment of the invention will be described in connection with what is one possible manner in which scanning of beam 10 over array 20 can be accomplished. The first embodiment is directed at an arrangement in which laser energy is moved between two scanning positions. That is, array 20 is scanned in sections equivalent to half the array.
Beam 10 is scanned across fiberoptic array 20 as is suggested by arrow 21 indicating the direction of scanning. Array 20 is composed . . . -.

2cs6~no of a plurality of optical fibers 22, all of which aro of uniform diameter D. Scanner 12 moves dielectric mirror 13 so that beam 10 is displaced from its normal position 28 to a first scan position 24 to cover half of the optical fibers, from one end of linear array 20. The laser pulse from the laser irradiates the optical fibers encompassed by the first scan position. In this embodiment, first scan position 24 includes those fibers within side section 25 and half of the fibers falling within normal position 28.
Thus, the first pulse from excimer laser/linear focusing optics 70 irradiates half of the linear array 20. 0 course, as suggested earlier, the first pulse may irradiate 1/3 or 1/4 or any other fraction of the fiberoptic array.
The pulse is not scanned on a fiber by fiber basis, but rather each pulse irradiates at least two optical fibers 22. In the embodiment depicted in the drawings, each pulse irradiates approximately twelve optical fiber. If the first pulse from laser and optics assembly 70 was intended to irradiate 1/3 of array 20, then only eight optical fibers would be illuminated by each pulse. When only 1l4 of the linear array is illuminated with each pulse, then in the pictured embodiment, 8iX fibers would be illuminated by each pulse as the beam is scanned over array 20.
After the laser pulse from the excimer laser is directed to those optical fibers falling within first scan position 24, scanner 12 moves dielectric mirror 13 so as to direct the next laser pulse to second scan position 26. Second scan position 26, in this embodiment, encompasses the fibers not falling within first scan position 24. That is, the second scan position 26 includes the second half of the linear fiber optic array 20 . . .
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zos~mo including fibers within side section 27 and half of the fibers within normal position 28. As described above, fiber optic array 20 could be scanned in a manner other than by half per pulse.
If this were the case, the second pulse from laser and optics assembly 70 could be directed at the second third, second quarter, etc. of array 20.
The ability of the present invention to scan the energy source over array 20 enables a reduction in the energy per pulse (or the cw equivalent) supplied to the patient and therefore the size of the energy source. Further, since more than a single fiber is being irradiated with each excimer laser pulse, the optics needed to focus pulsed beam 10 are simple as can be seen in U.S. Patent 5,016,964.
An array of optical fibers such as that described above is formed by the following process. First, the optical fibers are cut with, for example, a cutting stone. The cut end is then cleaned with alcohol. The fibers are then sorted into as many bundles as there are groups of fibers to be irradiated. For example, if half the array of optical fibers is irradiated with each pulse, the fi~ers would be sorted into two groups. A
piece of shrink tubing is then placed over the bundle. The fiber bundle is then inserted into the handle of the male plug portion (to be described with reference to FIGURES 10 and 11).
At least one inch of the plastic coating covering the fibers is then stripped off the fibers using a furnace set between 600C and 800C. The fiber bundle is then placed on a substrate of a male coupling portion will be described. The bare fibers should extend past the end of the substrate and stick out by about 25 ~m. A portion of covering the fibers extendc onto the substrate. A

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2c96~no curable adhesive, such as NORLAND 123 W, is applied to the tubing so as to couple the tubing to the substrate, being careful not to apply an adhesive to the fibers. The adhesive is then cured under W light.
The fibers are then spread into a single row on the substrate. It is important that the fibers be maintained in their respective groups that they were sorted into earlier. This is done by using a distal spreading apparatus ad~acent the substrate to maintain a space between ad~acent groups of fibers. The distal spreading apparatus abuts the substrate and includes a ridge or projection disposed thereon, running parallel to the fibers, to maintain the separation of tha overhanging fibers. It is desirable not to irradiate the end fiber(s) of each group by successive pulses of the laser beam, and this is ensured by spacing the groups of fibers on the substrate.
once the fibers are spread across the substrate, a needle or other aid is used to straighten the fibers. Adhesive is then applied to the fibers. For example, one drop of NORLAND
81 is applied to catheters having less than 25 fibers while two drops are used for catheters having more than 25 fibers. The adhesive is then gently spread over the fibers. Once any bubbles that might have formed in the adhesive are removed, the adhesive is cured using W light.
The overhanging fibers are then cleaved near the substrate. The fibers are then polished.
Another embodiment of a fiber array that may be used is pictured in FIGURES 3a and 3b.
3S FIGURES 3a and 3b depict 2 x 12 linear array of optical fibers 100. Certainly, the array can be scanned in two or more segments (2 x 6, if two -.:

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2C9fi~00 segments are assumed) in the manner described with respect to FIGURES 1 and 2 above. The energy source would simply be less tightly focused to simultaneously irradiate two rows of fibers.
Alternatively, as illu~trated in FIGURES 3a and 3b, the first laser pulse may be focused on part of the array 110 that is 1 x 12 in size and then the apparatus directs the second pulse at remaining fibers 120 that are also dimensioned 1 x 12. Of course, more than two rows of fibers may be provided and the rows of fibers may include a fewer or a greater number of optical fibers than the 12 pictured in FIGURES 3a and 3b.
To accomplish the scanning in the embodiment of FIGURES 3a and 3b, either the beam deflection can be shifted using equipment similar to that illustrated and described with respect to FIGURE 1. Alternatively, the fiber array can be shifted as illustrated in FIGURE 4.
FIGURE 4 illustrates an apparatus for translating the fiber array for irradiating different portions of optical fiber array 100.
Piezo crystal stack 400 expands and contracts, as indicated by arrow 406, in response to signal 404 sent from piezo crystal driver electronics 402.
Piezo crystal driver electronics 402 is controlled by signal 58 from laser trigger 52, which in turn is controlled by laser microprocessor 50. Laser microprocessor 50 and laser trigger 52 are described further with respect to FIGURE 7.
Stacked optical fiber array 100 is secured to fiber mounting substrate/coupler body 408. In turn, fiber mounting substrate 408 may be secured to an element such as spring steel counter 410, which permits movement of the stacked fiber - array 100 as piezo crystal stack 400 expands and contracts. Translator reference surface 412 is , . - .
. :, : .,,: . .
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2096~00 provided for proper alignment of optical fiber array 100 80 that portions of fiber array 110 and 120 are sequentially irradiated.
The first pulse generated by laser 70 S (FIGURE 1) irradiates part of optical fiber array 110 pictured in FIGURE 3a. The piezo crystal stack then expands so that part of optical fiber array 120, as pictured in FIGURE 3b, i8 irradiated. Note that in FIGURE 4, portions 110 and 120 contain only eight fibers apiece rather than the twelve depicted in FIGURES 3a and 3b.
Additional embodiments of the array of optical fibers are shown in FIGURES 5a and 5b.
FIGURE Sa illustrates a grooved fiber holder 205 holding two equally sized bundles of fibers 200 and 210. Bundles 200 and 210 are centered upon the same linear transverse axis 225. The laser beam is focused so that the first incident beam pulse 215 irradiates all of fiber bundle 200, which is half of the total fibers. Either the beam or the fibers are then shifted so that next pulse 220 of the laser beam is focused on bundle 210.
FIGURE 5b illustrates three bundles of optical fibers 300, 305 and 310. Each bundle of fibers 300, 305 and 310 contains 1/3 of the total ; number of fibers. The optical fiber bundles are disposed in a grooved fiber holder 315. First scan position 325 irradiates fiber bundle 300.
The beam and fibers move relative to one another to irradiate fiber bundle 305. The next laser pulse i8 directed at third bundle of optical fibers 310, which fall in third scan position 335.
As in FIGURE 5a, the fiber bundles are di~posed in a linear manner along the same transverse axis 320 to provide for linear scanning.

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FIGURE5 8a and 8b illustrate plug portion 800 of a laser catheter having an array of optical fibers who~e proximal end are disposed as depicted in FIGURE 5b. Grooved fiber holder 315 is, for example, a plastic substrate having three grooves formed therein. Fiber bundle~ 300, 305 and 310 are disposed in the grooves in fiber holder 315.
Fiber holder 315 includes an inclined proximal face 806. Inclined face 806 slopes inward from the bottom surface of fiber holder 315 in the direction of plug handle 808.
Plug portion 800 also includes an upper plate 802. Upper plate 802 is preferably formed of molded plastic and is connected to fiber holder 315 via connecting members 810, 812, which are formed integral with upper plate 802. Like fiber holder 3~5, upper plate 802 includes an inclined face, specifically inclined face 804.
Inclined face 804 slopes inward from the top surface of upper plate 802 in the direction of plug handle 808.
Inclined faces 804 and 806 allow for the fiber bundles to overhang from fiber holder 315 and upper plate 802. It is also possible for faces 804 and 806 to be cut back from the rest of upper plate 802 and fiber holder 315. The main goal is to allow for the optical fibers to extend past the edge ~f the fiber holder 315 and the upper plate 802. Such an overhang as pictured in FIGURE 9j enhances the durability of the fibers by preventing input surface contamination, which can be caused by ablation by-products of the mounting substrate.
~ithin plug portion 800, fiber bundles 300, 305 and 310 are joined into a single bundle that exits plug portion 800 as catheter 600, explained below with reference to FIGURE 6.

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, 2cs6mo FIGURES 9a-9o depict the method of laying a fiber bundle into one groove on a fiber holder.
Such a method is utilized for each bundle held by the fiber holder.
S FIGURE 9a illustrates tail tubing 900 being pulled back from optical fiber bundle 902 so as to expose length "x", approximately equal to 1.875 to 2 inches, of fiber~ 305. In FIGURE 9b, a glue plug 904 is formed just below the end of tubing 900. Glue plug 904 is formed of a fast drying epoxy.
Crystal bond, or a similar potting material, 906 is applied to length y, measuring about .25 to .375 inches, along the bare fibers as shown in FIGURE 9c. A heat gun or hot box (not pictured) is then used to melt the crystal bond and heat the ends of the fibers. This allows crystal bond 906 to work in between the fibers to ensure good support during polishing. As pictured in FIGURE 9d, length q of shrink tubing 908 is shrunk over the potted area and fibers to provide extra support during polishing. Length q measures about .75 inches.
Utilizing a diamond wire saw (not pictured), the tip of optical fiber bundle 902 is cut such that crystal bond, or like potting material, 906 is trimmed as shown in FIGURE 9e.
Length z of optical fiber bundle 902 remains exposed, with length z being about 1.75 inches.
The tip of optical fiber bundle 902 is then pol~shed, by a device such as a BUEHLER polishing machine (not shown), using 12, 3 and .3 micron lapping paper. Polishing is continued until all chips are gone and all fibers appear to have an optical quality polish.
Shrink tubing 908 is then remo~ed from optical fiber bundle 902. This is done by placing .: . .: . ~ - : .
: ., : ,, ,. . -~ :: : . . : ..

ZC961~0 the potted end in heat and sliding the shrink tubing off. The polished end of optical fiber bundle 902 is then suspended in acetone and placed in ultrasonic cleaner 80 as to remove completely crystal bond, or other potting material, 906.
Care must be taken not to damage or chip the polished fibers as the potting material 906 is removed from the end of optical fiber bundle 902.
This step i8 depicted with reference to FIGURE 9f.
Polyimide is then stripped off length w of fiber ends by placing the optical fiber bundle in a tube furnace (not shown) at a temperature of about 780 F for 1.5 minutes. Thus, exposed fibers 910 are left. These must be handled quite carefully, since the fibers are quite fragile.
Length w is approximately equal to 1 inch. FIGURE
9g illustrates this step.
In FIGURE 9h, an approximately 1.25 inch piece of shrink tubing 912 is positioned 80 that it overlaps the stripped portion of fibers by length v, which is about .125 inches. Shrink tubing 912 is then shrunk. Still, care must be taken when manipulating exposed fihers 910 as they remain fragile.
~IGURE 9i illustrates the mounting slide upon which the optical fiber bundle is to be disposed. For the purpose of inserting optical fiber bundles 300, 305 and 310 onto a slide with three grooves, this process is repeated three times.
FIGURE 9j illustrates the insertion of ~ibers into the groove on the slide. Optical fiber bundle 902 is positioned in the groove so that the ends of the polished fibers are flush with the end of the slide. Tip 916 of optical fiber bundle 902 projects past the end of the groove. Such a structure enhances the durability , .~ .

Z(~96~)0 of the fibers by preventing input surface contamination, which can be caused by ablation by-products of the mounting substrate. Wetting the fibers with purified water makes it easier to insert optical fiber bundle 902 into the groove.
Quartz-filled ultraviolet cure adhesive 914 tacks the fibers to the slide.
As pictured in FIGURES 9k and 91, pressure is applied to wetted fibers 910 using a silicone or rubber wedge 918. While observing with a microscope (not pictured), tip 916, which still has wet optical fibers, is probed and manipulated, carefully and gently, so that fibers 305 are positioned into a rectangular close pack.
FIGURES 9m and 9n illustrate how fibers 910 are tacked into the groove. While pressure is maintained using the silicone or rubber wedge 918, tack 920 is placed on exposed fibers 910. This step is performed while the fibers 910 are still wet. It is desirable not to disturb the packing of fibers 910. Finally, in FIGURE 9o, the entire grooved fiber assembly is potted, thus allowing the fibers to remain positioned in the groove.
The same procedure described with reference to FIGURES 9a-9o is followed for all other fiber bundles to be disposed on a slide.
FIGURE 6 illustrates the present invention used in a laser catheter assembly.
Laser 70 generates beam 10, which is transmitted to directing and coupling apparatus which implements either the apparatus of FIGURE 1 or FIGURE 4. Laser beam 10 enters catheter 600 from the directing and coupling apparatus. Proximal end 605 of catheter 600 connects to the directing and coupling apparatus. Proximal end 605 may be shaped as a stacked fiber array as shown in FIGURES 3a and 3b. Of course, proximal end 605 ; .; :
: : , : :

2C9~
may also be in the form of fiber array discussed with respect to FIGURES 5a and Sb.
The stacked fiber array at the proximal end of any of the forms described above turns into a substantially circular fiber bundle for use as a catheter. Distal end 601 of catheter 600 i8 substantially circular and is inserted into the patient.
In the assembly procQss, the fibers are sorted 50 that adjacent fibers at distal end 601 are irradiated simultaneously. Thus, for a fiber array at the proximal end that is irradiated in two portions, the fibers of one portion form portion 602. Likewise, fibers of the other portion become portion 604 at distal end 601 of catheter 600.
Control of scanner 12 in FIGURE 1 will now be explained with reference to FIGURE 7.
Laser microprocessor 50 communicates with trigger circuit 52 via signals 54 and 56. Signal 54 is a scan enable signal which indicates that the laser system is operational and that scanning is desired. When the laser is to be fired, microprocessor 50 generates thyratron trigger signal 56 to cause a thyratron in the laser drive circuit to conduct, triggering the laser. While scan enable signal 54 is enabled, after the laser has fired, trigger circuit 52 generates a signal on line 58 which causes scanner 12 or piezo electric stack 400 to move so that the next portion of fibers will be irradiated with the next ; firing of the laser. The signal on line 58 is, for example, a square wave that incrementally moves scanner 12.
Trigger circuit 52 may include a D flip-flop that receives scan enable signal 54 as an enabling signal and thyratron trigger signal 56 as .

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a clock signal. The output of the flip-flop may be amplified before being applied to ~canner 12 or piezo electric stack 400. In the preferred embodiment, scan enable signal 54 remains at a continuous level during scanning. During ablation, thyratron trigger signal 56 periodically triggers a laser pulse. After each laser pulse, scanner 12 or piezo electric stack 400 is actuated so that the next portion of fibers will be irradiated with the next laser pulse.
A mechanism particularly well suited for use in a scanning system is depicted in FIGURES 10 and 11, where fiberoptic catheter 600 is attached to male coupling portion 1020. Male coupling portion 1020 includes handle member 1003, slide 1000 and base substrate 1018. Handle member 1003 allows easy handling as well as preventing any extraneous laser radiation from being emitted.
Optical fibers are disposed between slide 1000 and base substrate 1018. Substrate 1018 may hold array 20 of FIGURE 2, array 100 of FIGURE 3 or be holder 205 or 315 of FIGURE 5a or 5b, respectively.
Male coupling portion 1020 attaches to female coupling portion 1022. Female coupling portion 1022 receives male coupling portion 1020 in a groove or aperture formed therein. The shape of the groove or aperture is such that slide 1000 and substrate 1018 fit snugly therein. Keying pin 1002 provided on male coupling portion 1020 is used to identify the size of fiberoptic catheter 600. Pins 1002 come into contact with micro switches 1004 disposed in female coupling portion 1022. The manner in which pins 1002 contact switches 1004 controls the unique signal generated by micro switches 1004. Between male and female coupling portions 1020 and 1022 is compressible .. ; .. ~..... . . :
.

2C96~0 foam member 1001, which prevents leakage of la~er radiation when male coupling portion 1020 i8 inserted into female coupling portion 1022.
Male coupling portion 1020 is held in place in female coupling portion 1022 by spring plunger 1016 and reference balls 1006 and 1012.
Spring plunger 1016 provides pressure to seat coupler on back reference ball 1006 and locks male coupling portion 1020 in female coupling portion 1022 when spring plunger 1016 drops into a v-groove (not ~hown) formed in slidQ 1000.
Reference ball 1006 guides the protruding portion of the male coupling portion 1020 into the receiving groove or aperture in female coupling portion 1022. Reference ball 1012 provides repeatability by pressing the substrate 1018 with optical fibers disposed thereon into a position such that the fibers are illuminated by the laser radiation. Spring steel shutter 1010 provides pressure on the back of the substrate 1018 so that reference ball 1012 is seated appropriately. .Further, spring steel shutter 1010 blocks the laser beam when male coupling portion 1020 is removed from female coupling portion 1022.
Female coupling portion 1022 connects to laser and optics assembly (not shown) via use of mounting plate 1008. The mounting plate and female coupling portion 1022 are slip fit so that the coupler may be rotated to correct or improve alignment. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent , 2C~9~
arrangements included within the spirit and scope o~ the appended claims.

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Claims

1. An apparatus for ablating tissue having means for producing a pulsed output beam and means for focusing the output beam (70), an array of optical fibers (100), a female coupling portion for receiving the focused beam (1022), a male coupling portion (1020) with a proximal end of said array of optical fibers attached thereto in a linear array, said male coupling portion being detachably coupled to said female coupling portion, means for scanning said focused output beam across said array of optical fibers (12), characterized in that:
said scanning means moves said focused output beam in synchronism with pulses from said producing means so that successive pulses of said beam irradiate at least two and less than all of said fibers and so that successive pulses irradiate different fibers.

2. An apparatus for ablating tissue as claimed in claim 1, further characterized in that said array of optical fibers includes a plurality of bundles (200, 210 or 300, 305, 310) disposed in a grooved fiber holder (800).

3. An apparatus for ablating tissue as claimed in claim 1, further characterized in that said scanning means includes a piezo electric stack (400).

4. A grooved fiber holder (800) for an apparatus for ablating tissue as claimed in claim 2, characterized in that said grooved fiber holder (800) includes a first plate member (315) having a plurality of grooves disposed thereon, said grooves for retaining said bundles of optical fibers (300, 305, 310), each groove containing at least two fibers.

5. An apparatus for ablating tissue as claimed in claim 1, further characterized in that said means for producing a pulsed output beam (70) is an excimer laser.

6. A coupling apparatus for coupling a source of energy to a catheter, said coupling apparatus including a male portion (1020) and a female portion (1022), wherein said male portion comprises a handle portion (1003) having an optical fiber catheter (600) extending therefrom, a first plate member (1018) attached to said handle having optical fibers of said catheter disposed in an array on a first surface thereof, a second plate member (1000) attached to said handle so as to oppose said first plate, and size indicating means (1002) for indicating a size of said optical fiber catheter, and wherein said female portion comprises means for interacting (1004) with said size indicating means and for providing a signal indicative of the size of the catheter, means for repeatably positioning (1006, 1012) said male portion in a position so that energy may be coupled to said catheter, and means for blocking (1010) said energy when said male and female portions are not coupled, characterized in that:
said fibers are disposed in grooves formed on said first surface.

7. The coupling apparatus as claimed in claim 6, characterized in that said source of energy is an excimer laser and said coupling apparatus joins said excimer laser to said fiberoptic catheter.

8. An apparatus for ablating tissue comprising means for producing energy and focusing said energy (70), a bundle of optical fibers (20), a proximal end of said fibers being disposed in an array, means for directing (13, 15) said focused energy on a group of at least two and less than all of said fibers (25, 28, 27), and linear scanning means (12) for causing said directing means to direct said focused energy on groups of said optical fibers, characterized in that:
said linear scanning means moves in synchronism with bursts of energy output from said energy producing means so as to sequentially direct said bursts onto different groups of optical fibers.

9. An apparatus for ablating tissue as claimed in claim 8, further characterized in that said linear scanning means scans two groups of optical fibers.

10. An apparatus for ablating tissue as claimed in claim 8, further characterized in that said linear scanning means scans three groups of optical fibers.

11. An apparatus for ablating tissue as claimed in claim 10 or 11, further characterized in that said groups of optical fibers are disposed in a grooved fiber holder (800).

12. An apparatus for ablating tissue as claimed in claim 8, characterized in that said means for producing energy (70) is a pulsed excimer laser.

13. An apparatus for ablating tissue comprising means for producing a pulsed beam of energy and for focusing said beam (70), an array of optical fibers (300, 305, 310 or 200, 210), means for coupling said focused beam to said array of optical fibers, said coupling means including a male portion (1020) to which said array is attached and a female portion receiving said focused beam (1022), and means for directing (12) said beam onto at least two but less than all of said plurality of optical fibers, characterized in that said directing means generates relative movement between said array of optical fibers and said focused beam so that said focused beam is directed onto different optical fibers of said array in synchronism with pulses from said producing means.

14. An apparatus for ablating tissue as claimed in claim 13, further characterized in that said male coupling portion (1022) includes a grooved fiber holder (800).

15. An apparatus for ablating tissue as claimed in claim 13, further characterized in that said producing means (70) is a pulsed excimer laser.

16. An apparatus for ablating tissue as claimed in claim 14, further characterized in that said grooved fiber holder (800) includes a plurality of grooves disposed thereon.

17. An apparatus for ablating tissue as claimed in claim 13, further characterized in that said male coupling portion (1020) includes size indicating means (1002).

18. An apparatus for ablating tissue comprising means for producing energy and for focusing said energy (70), an array of optical fibers (300, 305, 310 or 200, 210), means for coupling said focused energy to said array of optical fibers, said coupling means including a male portion (1020) to which said array is attached and a female portion receiving said focused laser beam (1022), means for directing said laser beam onto at least two but less than all of said plurality of optical fibers, characterized in that said directing means is a piezo electric stack (400) and generates relative movement between said array of optical fibers and said focused laser beam so that said focused laser beam is directed onto different optical fibers of said array in synchronism with pulses from said laser.