Background of the Invention

The present invention relates generally to the field of laser surgical probes. More specifically, the present invention relates to a laser surgical probe in which laser energy is output generally transversely relative to the laser energy input to the probe.

Surgical techniques making use of laser technology have been developed for a variety procedures. In many of these procedures, the surgeon must operate a laser probe within a tightly confined body cavity or lumen. In other procedures, it is necessary for the surgeon to enter the laser probe from the side of the area requiring laser treatment. In still other laser procedures, the area requiring laser treatment is accessible only around a tight corner. Accordingly, there is a need for a laser probe which allows laser energy to be directed at a substantial angle relative to the laser energy input to the probe.

Summary of the Invention The present invention provides a laser surgical probe for receiving laser light along a longitudinal axis. The probe includes an optical apparatus configured to redirect the light at an angle to the longitudinal axis. Preferably, the optical apparatus comprises an intensifier and a diverter which cooperates to focus the laser light at a location displaced from the longitudinal axis. The probe forms an enclosed passage for propagation of the light to permit the probe to be inserted into an internal portion of a mammal without interrupting passage of light through the probe. Preferably, the probe is no more than 2.5 mm in diameter.

Another aspect of the present invention provides a laser surgical probe, comprising a housing and a waveguide, such as an optical fiber, for directing a laser light beam towards the housing along a longitudinal axis. An optical apparatus, preferably of dielectric material transparent to the light beam, is mounted in the housing such that it receives the

laser light from the optical fiber. The optical apparatus comprises a diverter, such as a reflecting surface, which redirects the light beam at an angle to the above-mentioned longitudinal axis, and an intensifier, such as a refracting surface, which concentrates the light beam, preferably after it has been redirected by the diverter portion. The intensifier can be a standard lens, a tapered tip and a microball. In a preferred embodiment, all of the components of the optical apparatus form a single unitary whole. The optical apparatus may also include a collimator for collimating the laser light beam prior to striking the diverting portion. The collimator can comprise a microball of dielectric material.

In one embodiment, the probe additionally comprises a preferably cylindrical waveguide between the reflecting surface and the refracting surface which guides the redirected light beam from the reflecting surface to the refracting

^' surface.

Preferably, the housing has a head element adapted for insertion into interior portions of a human or animal body along an axis of insertion. The head element is generally symmetrical about the axis of insertion and is smoothly contoured at its distal end to prevent the head element fro snagging upon insertion or withdrawal of the probe. Alternatively, the probe can have an outer housing encasin the probe, with the outer housing being contoured for smoot insertion and withdrawal into a human or animal body withou snagging.

In accordance with another aspect of the presen invention, there is provided a method of directing a lase light beam in a surgical procedure, comprising inserting laser probe into an internal portion of a mammal, directing laser light beam into the probe along a longitudinal axis, redirecting the laser light beam so that the beam exits th probe at an angle relative to the longitudinal axis, an concentrating the laser light beam at a location adjacent t the probe, which is preferably within 1 mm from the probe

The laser light beam can be collimated prior to redirecting the laser light beam.

In another aspect of the present invention, there is provided a laser surgical probe adapted for insertion into a human or animal body, comprising a head element having a diameter of 2.5 mm or less, an optical waveguide for directing a laser light beam towards the head element along a longitudinal axis, and at least one microball having a diameter of no more than 2.2 mm and mounted in the head element for intensifying the laser light beam. The probe can also include a reflecting surface for redirecting the light beam at an angle to the longitudinal axis and a second microball having a diameter of no more than 2.2 mm for collimating said laser light beam. Further objects, features and other advantages of the present invention will become apparent from the ensuing detailed description, considered together with the appended drawings.

- Brief Description of the Drawings

Figure 1 is a partially cut away, partially exploded, perspective view of the laser probe of the present invention.

Figure 2 is a perspective view of the assembly of the laser probe of Figure 1. Figure 3 is a partial cross-sectional view taken across line 3-3 in Figure 2.

Figure 4 is a schematic representation of the propagation path of laser light energy through the optical apparatus of the embodiment of the invention shown in Figures 1-3. Figure 5 is an elevation view in partial cross-section, of an alternative embodiment, showing a schematic representation of the propagation path of laser light energy through the optical apparatus.

Figure 6 is a perspective view of the rod used in the alternative embodiment of the laser probe of Figure 5.

Figure 7 is a partial cross-sectional view of another embodiment of the laser probe.

Figure 8 is a cross-sectional view of still anothe embodiment of the laser probe.

Figure 9 is a partial cross-sectional view of a varian of the laser probe of Figure 8. Detailed Description of the Preferred Embodiment

Referring now to the drawings in detail, wherein lik reference numerals designate like elements throughout th several views thereof, there is shown generally at 10 i Figure 1, a laser surgical probe embodying the presen invention in a preferred form. The probe 10 comprises a elongate housing 14, an optical fiber 18 and an optica apparatus 22. The maximum diameter of the housing 14 i presently mo more than 2.5 mm.

Referring to Figures 1 and 2, the housing 14 comprises fiber holder comprising an axially elongate hollow shaft, 2 and a head element 30 at the distal end of the shaft 26. Th term "distal" designates the direction away from the lase light source, to which the probe is optically coupled. Th term "proximal" shall mean the direction toward the lase light source 34. The term "longitudinal" shall be used t refer to a direction corresponding to an imaginary lin running between proximal and distal ends. In Figure l, portion of the shaft 26 is cut away to reveal the fiber 1 extending therethrough. The head element 30 is contoured for smooth insertio into interior portions of a mammal. In order to allow ^' th head element 30 to be withdrawn from the mammal withou snagging, the head element is generally symmetrical about th axis for insertion. The head element 30 is also smoothl contoured at its proximal and distal ends in order to preven snagging upon insertion or withdrawal of the probe 10. As a alternative, the entire probe 10 can be housed within an oute housing (not shown) which can be contoured for smoo insertion and withdrawal without snagging. The head element 30 is preferably constructed from metal such as aluminum or stainless steel. As best seen in Figu 3, the head element 30 has a hollow space including

longitudinal tubular cavity 38 and a transverse tubular cavity 39, which allow for insertion of the optical fiber 18 and optical apparatus 22 therethrough, respectively. The transverse tubular cavity 39 extends through the head element 30 to form top and bottom openings in the head element 30. The optical apparatus 22 is positioned into the head element through the transverse tubular cavity 39. As will be explained in more detail below, the optical apparatus 22 is held in place by crimping of the head element material. The hollow shaft 26, which extends into a proximal end of the longitudinal tubular cavity 38, can, advantageously, be formed from stainless steel hypodermic tubing.

The longitudinal tubular cavity 38 extends from the proximal opening nto the transverse tubular cavity. The diameter of the longitudinal cavity 38 is substantially the same as the outer diameter of the hollow shaft 26. The inner diameter of the shaft 26 is slightly larger than the outer diameter of the optical fiber 18. The optical fiber 18 is mounted in the hollow shaft 26. Referring now to Figures 1-3, the head element 30 and hollow shaft 26 together form a housing 14 for the optical fiber 18 and optical apparatus 22. The head element 30 and hollow shaft 26 can be held together by any suitable method, such as by gluing with cyanoacrylate or by press fitting, brazing, soldering, or the like. Alternatively, the head element 30 and hollow shaft 26 can be formed as a unitary whole.

The optical fiber 18 is used to conduct a laser light beam towards the housing 14 and ultimately into the optical apparatus 22. Accordingly, the optical fiber 18 is optically connected at its proximal end to the laser light source. A preferred optical fiber 18 is zirconium fluoride fiber, having a numerical aperture of 0.2, which will produce an output cone of light having half angle of 11.5°. Aluminum flouride fiber can also be provided. In the preferred embodiment, the fiber 18 is provided with a core and cladding of zirconium fluoride

-

-6- and a jacket of U.V. curable acrylate.

As best seen in Figure 3, the optical fiber 18 is fixedly mounted in the tubular shaft 26 by a sleeve 58 comprising a tubular piece of material with an inner diameter slightl larger than the optical fiber 18 and an outer diamete slightly smaller than the inner diameter of the shaft 26. Alternatively, the fiber 18 can be bonded in place with glu or other materials.

In the preferred embodiment, the optical apparatus 2 (described hereinbelow) forms a single integral whole.

As described above, the optical apparatus 22 receive laser light from the optical fiber 18 along the longitudina axis of the optical fiber. The optical apparatus 22 is forme from a dielectric material which is transparent to the beam o laser energy emanating from the optical fiber 18. Fo example, when an Erbium YAG laser is used as the laser ligh source 34, which produces laser energy at 2.94 μm wavelength sapphire is a preferred dielectric substance for formation o the optical apparatus 22. Advantageously, sapphire is readil machined into a variety of shapes useful as optical element in the practice of the present invention.

The optical apparatus 22 is configured to redirect lase energy coming from the optical fiber 18 at an angle to th longitudinal axis of the optical fiber. As best seen i Figure 1, the optical apparatus 22 comprises a diverte portion 62 and an intensifier portion 63. The diverte portion 62 reflects the laser energy output from the optica fiber 18. In the preferred embodiment, shown in Figures 1-3 the diverter portion 62 comprises a reflecting surface whic is planar and is oriented at a predetermined angle relative t the propagation path of the light incident thereon. Th reflecting surface is formed by a coating of reflectiv material which is 99.7% reflective at 2.94 μ (R^) •

As seen in Figures 1 and 3, in order to facilitat attachment to the head element 30, the optical apparatus 22 i provided with two notches 64. When the optical apparatus 2

-1- is positioned at its proper position within the head element 30, the outer surfaces of the head element 30 can be crimped onto the notches 64, thereby fastening the optical apparatus 22 to the head element 30. When the optical apparatus 22 is properly seated within the head element 30, a small cavity 65 remains above the optical apparatus 22. If desired, this cavity 65 can be filled or covered in order to protect the reflecting surface. Referring now to Figure 4, laser light energy entering the optical apparatus 22 from the optical fiber 18 will propagate through the optical element along its axis of egress from the fiber 18 until it reaches the diverter portion 62 of the apparatus 22. The diverter portion 62 is optically aligned and spaced from the optical fiber such that the output cone of laser light energy will cover the planar surface of the diverter portion 62 without significant amounts of laser energy loss. For the fiber used in this embodiment with a numerical aperture of 0.2, it is preferable that the distance 70 between the distal end of the fiber 18 and the proximal face of the optical element 22, measured along the longitudinal axis of the fiber, not exceed 0.02 inches. If the distance 70 exceeds this length, too much laser light energy may diverge outside of the reflective surface of the diverter portion 62. Laser light energy reaching the diverter portion 62 is redirected at an angle which depends on the geometry of the diverting portion 62. For example, where the diverter portion 62 comprises a planar reflecting surface, such as that shown in Figures 1-4, the light will be redirected at an angle corresponding to the angle of incidence of the laser light energy on the reflecting surface 68. The reflecting surface 68 of the preferred embodiment is disposed at an angle of 45° relative to the longitudinal axis of the light output from the optical fiber. As seen in Figure 4, this will produce an angle of divergence of the laser light energy of 90° relative to its initial axis of propagation. However, the reflecting

surface 68 can be configured to provide any desired angle of divergence; particularly those angles greater than 30°, and more particularly greater than 45°.

The intensifier portion 63 of the optical apparatus 22 is disposed to receive the laser light energy that is redirected by the diverter portion 62. The intensifier portion 63 serves to concentrate the redirected light beam. Thus, the intensifier portion 63 can comprise a refracting surface, such as a focusing lens or a tapered tip, which produces the desired intensifying effect. In a preferred embodiment, the refracting surface is, advantageously, formed from the same dielectric material as the remainder of optical apparatus 22. In the embodiment shown,, the refracting surface comprises a hemispherical lens 74. The hemispherical lens 74 is disposed at the end of a cylindrical rod portion 78 of the optical apparatus 22 which serves as a waveguide portion. The waveguide portion 78 guides the redirected light reflecting from the reflecting surface 68 toward the refracting surface. The hemispherical lens 74 has a radius of curvature equal to the radius of the cylindrical rod portion 78.

The hemispherical lens 74 focuses laser light energy emanating from the shaft portion 78 to focal point 79. One feature of the refracting surface 74 is that it has a focal point 79 very close to the point of exit of laser light exiting therethrough. Preferably, this focal point is less than one millimeter from the refracting surface.

Referring now to Figure 5, there is shown at 100, an alternative embodiment of the laser probe of the present invention. In this embodiment, an elongate housing 114 having a maximum diameter of 2.5 mm or less, the housing 114 comprises a head element 104 and a fiber holder 126, each of which is formed by an axially elongate hollow shaft, such as by hypodermic tubing. The outer diameter of the fiber holder 126 is approximately equal to the inner diameter of the head element 104, such that a distal end of the fiber holder 126

fits within a proximal end of the head element 104. The head element 104 has a circular opening 106 which provides access to the interior hollow portion of the housing 114 and also provides a route for egress of laser light energy. In addition to the head element 104, the embodiment shown by Figure 5 comprises an optical fiber 118. The optical fiber 118 may be the same as the optical fiber 18, described above in connection with Figures 1-3. The optical fiber 118 is connected to laser light source, such that laser light energy is transmitted through the optical fiber 118 in a longitudinal direction from proximal to distal. The optical fiber 118 is of smaller diameter than the inner diameter of the fiber holder 126, and thus a tubular optical fiber sleeve 158 is used to hold the optical fiber 118 in position within the housing 114. The fiber sleeve 158 has inner and outer diameters of a size sufficient to substantially fill the annular space between the fiber holder 126 and the optical fiber 118. The distal end of the optical fiber 118 is preferably co-terminous with the distal end of the fiber sleeve 158. The fiber sleeve 158 can be held to both the fiber holder 126 and the optical fiber 118 by interference fit. Alternatively, U.V. curable epoxy glue can be used to hold the sleeve 158.

In this alternative embodiment 100, the optical apparatus comprises separate components and is not unitary. A diverter portion 162 of the optical apparatus comprises a reflecting surface 168 formed by a reflective coating on the end of a sapphire rod. 170. This rod 170 has a diameter slightly smaller than the inner diameter of the head element 104. Thus, the rod 170 can be inserted into the head element 104 in order to position the reflecting surface 168 such that the reflecting surface 168 directs laser light energy out of the head element 104 through the opening 106.

As best seen in Figure 6, the rod 170 is provided with a disk 172 at its distal end which serves to prevent insertion of the rod 170 into the housing 104 further than the length of the rod 170. The rod 170 and disk 172 are preferably

constructed from a single unitary piece of material. The disk 172 preferably has a diameter equal to the outer diameter of ■the head element 104, and is provided with curved corners at its distal end in order to create a smooth contour at the distal end of the probe 104, thereby allowing for smooth insertion and removal of the probe 100. Preferably, an intensifier of the optical apparatus comprises a microball 174, having a spherical surface for refracting light. The microball 174 is preferably formed from dielectric material, such as sapphire, and can optionally be coated with an anti- reflective coating to increase optical transmission through the microball 174. Sapphire microballs 174 are, advantageously, easily fabricated, readily available and commonly used as couplers for fiber-optic cables. These microballs 174 are also. vailable in sizes of 2.2 mm or less. The microball 174 can be held on to the housing 114 by gluing it to the opening 106 with U.V. curable epoxy glue. Because the reflecting surface 168 is aligned to direct laser light energy from the optical fiber 118 toward the opening 106, placing the microball 174 within the opening 106 allows the microball 174 to perform its intensifying function on the light energy passing therethrough.

An optional feature of the optical apparatus of the various embodiments of the present invention is a collimator. The collimator serves to substantially collimate the laser light energy emanating from the optical fiber prior ^' to striking the diverting portion. In the alternative embodiment 100 shown by Figure 5, the collimator of the optical apparatus comprises a collimating microball 182, similar to the microball 174 described above in connection with the intensifier.

The collimating microball 182 is positioned between the optical fiber 118 and the diverter 162, immediately distal (e.g., about 0.02 inches) of the distal end of the optical fiber. It is important that the distance between the microball 182 and the fiber 118 be relatively small so as to cause collimation rather than focusing. Thus, light emanating

fro the distal end of the optical fiber 118 is collimated before reaching the reflecting surface 168. Such collimation of the laser light energy serves to reduce or eliminate spherical aberrations of the light passing through the microball 174.

Referring now to Figure 7, there is shown another embodiment of a laser surgical probe 200 of the present invention. The probe 200 comprises a fiber holder shaft 226 and a head element 230. The head element 230 is contoured for smooth insertion and withdrawal. The head element 230 has a longitudinal tubular cavity 238 and a transverse cavity 239. In this embodiment, the diameter of the transverse cavity 239 is constricted at the bottom relative to the remaining portion of the cavity 239, which is substantially tubular. . Thus, a ledge 246 is formed within the transverse cavity 239.

The optical fiber 218 of this embodiment is fit into the head element 230 in a manner similar to that described above in connection with Figures 1-4. The optical apparatus of this embodiment comprises separate pieces, namely a collimator 273, a diverter 262 and an intensifier 266. As described in connection with Figures 5-6, the collimator 273 and the intensifier portion 266 comprise microballs, optionally coated with an anti-reflective coating.

The diverter ^" 262 comprises a sapphire rod polished at a 45° angle at its distal end. The angled portion is coated with a reflective coating and forms a reflecting surface 268. The diameter of the rod is slightly smaller than the diameter of the longitudinal cavity 238 so that the diverter can be inserted therethrough. The intensifier microball 266 rests on the ledge 246 and the diverter 266 is inserted through the longitudinal cavity 238 such that the microball 266 is held in the space between the ledge 246 and the diverter portion 268. The collimator microball 273, like the diverter portion 266, has a diameter slightly smaller than the diameter of the longitudinal cavity 238, and is inserted proximally of the diverter portion 266.

Finally the optical fiber 218 within the shaft 226 is inserted into the longitudinal cavity 238. The shaft 226 is held to the proximal end of the head element 230 with U.V. curable glue. Thus, the diverter portion 266 and the collimator microball 273 are held within the portion of the longitudinal cavity 239 distal of the shaft 226. Preferably, there is substantially no space between the intensifier microball 266 and the diverter 262 or between the diverter 262 and the collimator microball 273. Referring now to Figure 8, there is shown still another embodiment of a laser surgical probe 300 of the present invention. The probe 300 comprises an optical fiber 318, a head element 330 and a fiber holder 358. The fiber holder 358 serves to provide a grip for the operator of the probe 300 and also serves as a sleeve for the optical fiber 318.

The head element 330 has a tubular longitudinal cavity 338 having proximal, middle and distal sections. The middle section has a constricted diameter relative to the proximal and distal sections of the cavity 338. The proximal section of the cavity 338 is threaded to accept a threaded portion 392 of the fiber holder 358.

The optical apparatus of the probe 300 comprises an intensifier 366 and a diverter 362. The intensifier comprises a spherical microball which is disposed in the distal section, and which rests on a ledge 346 formed by the constricted diameter of the middle section of the longitudinal cavity 338.

The diverter 362 comprises a sapphire rod polished at a

45" angle at its distal end. The angled portion is coated with a reflective coating to form a reflecting surface 368. The diameter of the rod is slightly smaller than the diameter of the longitudinal cavity 338 so that the diverter can be inserted therethrough. The diverter 362 can extend beyond the distal end of the head element 330 as shown, or can be encased by the head element 330, with a hole at the point of emission of laser light energy. If the diverting portion extends

beyond the distal end of the head element 330, the exposed sapphire can optionally be coated with a protective over-coat. The distance between the distal end of the fiber 318 and the proximal portion of the intensifier microball 366, and the distance from the distal portion of the intensifier microball and the reflecting surface are selected so as to produce a focal point 379 a desired distance (e.g., less than 1 mm) from the bottom of the diverter 362. The distance from the intensifier microball 366 and diverter 362 can also be manipulated to provide the desired focal point 379. However, preferably, an input surface 370 of the diverter 362 is touching or almost touching the intensifier microball 366 in order to prevent axial movement of the microball 366.

The diverter 362 can be held in place by providing a notch 364 on the head element 330 and crimping the notch 364 to the diverter 362. If desired, the input surface 370 of the diverter 362 and the entire or proximal surface of the intensifier microball 366 may be coated with an anti- reflective coating to minimize reflection. In use, the probe 300 is inserted into an internal portion of a mammal (e.g. an eye cavity) such that the rod 362 is surrounded by tissue and the portion of the rod extending from the housing is in contact with the tissue, although in the embodiment disclosed, the light beam is redirected by- reflection, it will be understood that, by eliminating the reflective coating so that the light passes through the angled output face, redirection by refraction could be achieved. Such refraction is due to differences in refractive index at the angled output face. Redirection of the light beam by refraction may be similarly achieved by utilizing a bare rod, such as an optical fiber, and cleaving the end of the fiber of an angle (e.g. 45°) to cause the light output from the fiber to be deflected. Nevertheless, use of the reflective coating is preferred because a greater angle of deflection is possible.

Referring now to Figure 9, there is shown a variant 310 of the laser probe 300 of Figure 8. In this variant, the head element 330 is elongated to extend beyond the diverter 362, and comprises an opening 306 to allow laser light energy to be emitted outside the head element 330 after it has been diverted by the diverter 362. In the variant 310, a cap 394 is inserted at the end of the head element 330. The cap 394, comprises a rod portion 395 and a flange portion 396. The diameter of the rod portion 395 is slightly smaller than the diameter of the longitudinal cavity 338 so that the rod portion 395 can be inserted therethrough. The rod portion 395 is cut an angle which will complement the angle of end the diverter rod 362 to substantially completely fill the longitudinal cavity 338 at its end. Thus, if the diverter rod 362 is cut at,a 45° angle, the rod portion 395 will also be cut at a 45° angle. The length of the rod portion is selected to substantially completely fill the end of the longitudinal cavity 338. The flange portion 396 provides a smooth surface for easy insertion and withdrawal of the variant laser probe 310. The cap 394 is held in place by crimping the notches 364 to the cap 394, thereby also preventing axial movement of the diverter rod 362.

The laser probes 10, 100, 200, 300 of the present invention are useful in a wide variety of surgical procedures where it is desired to operate a laser probe within a tightly confined space, such as within bodily tissues or a tightly confined body cavity or lumen. The probe allows a surgeon to direct laser energy from the side of the probe, thereby allowing laser energy to be directed around tight corners. Particular examples of procedures in which the probe can be applied in a mammal include ophthalmic procedures of many types, surgery within a joint, such as a knee, and procedures within the urethra. The intensity of the light input to the probe is regulated, depending on the procedure, to provide sufficient intensity at the focal point of the intensifier to

achieve the desired result such as cutting, welding, vaporization or coagulation of biotic material (e.g. tissue) . It will be appreciated that certain structural variations may suggest themselves to those skilled in the art. The foregoing detailed description is to be clearly understood as given by way of illustration, the spirit and scope of this invention being limited solely by the appended claims.