Method and Apparatus for Tapering a Laser Optical Fiber to a Fine Point

Background of the Invention

The present invention relates to a method and apparatus for shaping and reshaping the tips of optical fibers for use in laser surgery or other applications of lasers utilizing optical fibers for cutting materials.

The application of laser technology to sur<~ al procedures has rapidly proliferated to include a vai ty of medical arts such as laser surgery, laser angioplasty, laser eye surgery, cosmetic surgery and dentistry. In laser surgical applications it is frequently desirable to utilize an optical fiber which has been tapered to a fine point at its end. The pointed end concentrates the energy of the laser beam at the tip to allow precise and efficient cutting of tissue or other materials. However, with repetitious use of the same optical fiber for laser surgical procedures, the tapered end tends to degrade over a relatively short period of time. Addi¬ tionally, the optical fiber may accidentally be chipped or broken. It is current practice among surgeons performing laser surgery to discard broken or worn optical fibers. Consequently, surgeons who utilize lasers are required to purchase many expensive prefabricated optical fibers to maintain a sufficient supply to compensate for the deteri¬ oration and breakage of laser fibers. Due to the rela- tively high cost of prefabricated optical fibers and the need to maintain an inventory of them for laser surgery, few practitioners can afford to take advantage of laser surgical techniques.

Although machines for grinding optical fiber material exist, they are not adequate for tapering optical fibers to appropriate tips for laser surgery, nor, for use in a surgical setting. For example, United States Patent No.

4,999,955 describes a Method and Apparatus for Conically Machining Optical Fiber Connectors. The apparatus dis¬ closed is designed for use by trained personnel in the field to grind to a point optical fiber connectors for optical communications and optical sensors. This patent actually teaches away from one embodiment of the present invention by noting that machines employing a concave grinding surface are disadvantageous. Additionally, the apparatus disclosed in the 4,999,955 patent requires two motors and rotates the optical fiber. In the present invention the optical fiber remains stationary in order to prevent twisting of the optical fiber and unnecessary breakage. As a result, only one motor is required, such as an air or brushless D.C. motor, which may be part of the tip forming apparatus or may conveniently utilize a drill commonly found in dental offices or surgical rooms. United States Patent No. 4,914,866 discloses a relatively bulky apparatus for adjusting alignment surfaces on com¬ munication optical fiber terminating plugs and connector sleeves. Unlike the present invention, this apparatus could not be readily adapted for sharpening optical fibers for laser surgery or for use in a surgical setting.

Summary of the Invention

The present invention is directed to a method and apparatus for tapering optical fibers to a fine pointed end for use in laser surgery or any application involving the cutting of material by a laser utilizing an optical fiber with a pointed tip. The present invention allows a user to shape or repeatedly reshape an optical fiber for multiple reuses greatly extending the life of an optical fiber. By utilizing an air motor, a high speed induction motor, or a brushless D.C. motor the apparatus may be conveniently employed in a surgical setting.

Brief Description of the Drawings

FIG. 1 is an elevational view depicting the preferred embodiment of an apparatus for shaping optical fibers.

FIG. 2 is a sectional view illustrating an alternate embodiment of an apparatus for shaping optical fibers.

FIG. 3 is an elevational view showing an alternate embodiment of an apparatus for shaping optical fibers.

Detailed Description of the Invention

FIG. 1 depicts the preferred embodiment of the apparatus for shaping optical fibers for use in laser surgery. Optical fiber 2 is inserted into a collet 4, or another retaining element such as a chuck, which is mounted onto sliding block 6. Movable stop 8 is attached to sliding block 6 to set the fiber end to be shaped or reshaped at a predetermined position. Sliding block 6 is mounted on base plate 10 by a rail or guide (not shown) such as a square way, round rail, or dovetailed rail. Shaft 14 is connected to a high speed motor 16 at one end and the opposite end contains a fabricated hollow inverted cone 18. The high speed motor 16 may be any of a variety of high speed motors for example a brush type D.C. motor, a high speed induction motor, an air motor, or a brushless D.C. motor or conveniently a dental or surgical drill. The high speed induction motor, air motor, and brushless D.C. motor are preferred for use in a surgical setting where flammable material may be present because they do not arc or spark. These motors are also preferred for a surgical setting because they do not emit dust. The high speed motor 16 is held in position by motor mount 19 which is attached to base plate 10 in a fixed position. Shaft 14 is positioned such that the hollow inverted cone faces moveable stop 8. The hollow inverted cone 18 is imbedded with a fine abrasive material preferably a diamond grit. Other fine abrasive materials which might be suitable are aluminum oxide, cerium oxide, silicon carbide, cubic boron nitride, or other superabrasives. Fixed stop 12 is

mounted on base plate 10 beneath shaft 14 at a predeter¬ mined position which allows proper laser optical fiber tip shaping, yet minimizes optical fiber loss due to grinding. To operate the described apparatus, optical fiber 2, preferably with a cleaved end, is inserted into collet 4 such that the cleaved end abuts moveable stop 8. The collet 4 is tightened, moveable stop 8 is removed and sliding block 6 is pushed towards the hollow inverted cone 18 contained within shaft 14. While sliding block 6 is moving towards hollow inverted cone 18, high speed motor 16 turns shaft 14 containing hollow inverted cone 18. As sliding block 6 approaches hollow inverted cone 18, opti¬ cal fiber 2 enters hollow inverted cone 18 and is ground to a tapered tip by the abrasive material lining hollow inverted cone 18. Openings in the side of hollow inverted cone 18 (not shown) , such as perforations, or transverse or longitudinal slits, allow the optical fiber cuttings to exit the hollow inverted cone 18 without clogging it. Grinding of optical fiber 2 continues until sliding block 6 abuts fixed stop 12 at which point optical fiber 2 has been ground to a tapered tip of the desired dimensions, typically, for surgical applications, a tip of 75 to 400 microns in diameter, by hollow inverted cone 18. Alternatively, high speed motor 16 and motor mount 19 may be attached to base plate 10 by a rail or guide such that the hollow inverted cone can be moved towards sliding block 6 which can be attached to base plate 10 in a fixed position.

FIG. 2 illustrates another grinding mechanism for the above described optical fiber shaping apparatus embodiment with cutting means consisting of a grinding wheel config¬ uration 20 which includes a pair of grinding wheels 22, a pair of pin shafts 24, driving gears (not shown) , and high speed motor 26. A pair of grinding wheels 22 are rotat- ably mounted on pin shafts 24. Pin shafts 24 are attached to the driving gears of a high speed motor 26 or other similar driving means which is mounted to base plate 10 in

a fixed position. As in the previous embodiment, optical fiber 2, preferably with a cleaved end, is inserted into a collet 4 which is mounted onto sliding block 6. Move¬ able stop 8 (not shown) is attached to sliding block 6 to set the fiber end to be reshaped at a predetermined position. Sliding block 6 is mounted on base plate 10 by a rail or guide (not shown) . Sliding block 10 is moved towards grinding wheels 22 so that optical fiber 2 enters the opening between the grinding wheels 22 which have an abrasive consistency suitable for sharpening optical fibers, such as a fine diamond grit surface. As optical fiber 2 enters the opening between grinding wheels 22, the cleaved end of optical fiber 2 is ground to a tapered tip by grinding wheels 22. Grinding of optical fiber 2 continues until sliding block 6 abuts fixed stop 12 at which point optical fiber 2 has been ground to a tapered tip of the desired dimensions, typically, for surgical applications, a tip of 75 to 400 microns in diameter, by grinding wheels 22. Alternatively, the grinding wheel configuration 20 may be attached to base plate 10 by a rail or guide such that the grinding wheels 22 can be moved towards sliding block 6 which can be attached to base plate 10 in a fixed position.

FIG. 3 shows another embodiment wherein the optical fiber tip is shaped by a heated mold 40 with a hollow inverted cone 36. Heated mold 40 is wrapped in heating coil 30 and structurally supported by frame support 38 which is in turn attached to base plate 10 by mount 19. Voltage for heating coil 30 is provided by voltage gener- ator 32 and is transmitted to heating coil 30 by insulated wires 34.

Heated mold 40 and hollow inverted cone 36 are heated by heating coil 30 to a desired temperature for forming a tapered optical fiber tip. An optical fiber 2, preferably with a cleaved end, is inserted into a collet 4 such that the cleaved end abuts moveable stop 8. The collet 4 is tightened, moveable stop 8 is removed and sliding block

6 is moved along a rail or guide (not shown) towards heated mold 40. As sliding block 6 approaches heated mold 40, optical fiber 2 enters hollow inverted cone 36. The heated mold 40 and hollow inverted cone 36 melt the end of optical fiber 2 to a tapered tip of desired dimensions, typically, for surgical applications, a tip of 75 to 400 microns in diameter. As in the above embodiments, fixed stop 12 stops sliding block 6 at a predetermined distance to minimize optical fiber loss. Alternatively, the heated mold assembly may be attached to base plate 10 by a rail or guide such that heated mold 40 can be moved towards sliding block 6 which can be attached to base plate 10 in a fixed position.

While various apparatus and methods of tapering optical fiber tips for laser surgery have been described in order to make the invention known to those skilled in the art, it should be readily apparent that many more modifications of the techniques disclosed are possible without departing from the inventive concepts contained herein. ' Indeed, the present invention could be readily adapted to a plethora of commercial settings wherein optical fibers are employed in conjunction with a laser for the cutting of a variety of materials. The foregoing description, therefore, should be taken as illustrative and not limiting in any sense.