WO1998018394A1

WO1998018394A1 - Variable angle surgical laser handpiece

Info

Publication number: WO1998018394A1
Application number: PCT/US1997/019030
Authority: WO
Inventors: Charles Christopher Negus; Lawrence P. Brodsky
Original assignee: Plc Medical Systems, Inc.
Priority date: 1996-10-30
Filing date: 1997-10-20
Publication date: 1998-05-07

Abstract

A variable angle surgical laser handpiece (20) includes a fixed member (24), and a movable member (26) rotatable mounted to the fixed member (24) for rotation about a rotation axis (28) through a range of rotational angles; a passage (38, 40) through the members (24, 26) for transmitting a laser beam (32); a port (30) in the movable member (26) for delivering the laser beam (32) to a surgical target; a deflection device (36) rotatable mounted on the rotation axis (28) for directing the laser beam (32) from the fixed member (24) through the movable member (26) and port (30); and a control mechanism (50, 80, 90, 120) for constraining rotation of the reflection device (36) to one half the rotational angle of the movable member (26) to maintain the alignment of the laser beam (32) with the passage (38, 40) and port (30) throughout the range of rotation of the movable member (26).

Description

VARIABLE ANGLE SURGICAL LASER HANDPIECE

FIELD OF INVENTION This invention relates to a variable angle surgical laser handpiece.

BACKGROUND OF INVENTION In endoscopic laser surgery a handpiece is used to deliver a laser beam to a surgical target. The laser beam propagates through a passage in the handpiece barrel or member and an output port to the patient. In order to minimize the number and/or size of the surgical incisions, handpieces with different angles are used. For example, in transmyocardial revascularization (TMR) a number of different angle handpieces are used to reach areas on the sides and back of the heart. While this approach does reduce the number and size of incisions, the surgical unit must purchase and keep on hand a number of handpieces of different angles and the surgeon must interrupt an already difficult and time-consuming procedure to switch handpieces one or more times. In addition to extending the time of exposure of the patient to a surgical procedure there is the added potential for problems in contamination and mechanical installations brought about by the extra handling in interchanging the handpieces. The idea of a single variable angle handpiece has occurred but the problem is that when one part of the handpiece moves relative to the other, the deflection device such as a refracting prism or reflecting mirror, must be moved at a different rate of angular rotation in order to keep the beam coincident with the passage through the handpiece. This requires that a complex and expensive mechanism be installed in a handpiece which must be kept as small as possible for patient comfort and safety.

SUMMARY OF INVENTION

It is therefore an object of this invention to provide a variable angle surgical laser handpiece.

It is a further object of this invention to provide such a variable angle surgical laser handpiece which provides the convenience of a number of different fixed angle handpieces in a single handpiece. It is a further object of this invention to provide such a variable angle surgical laser handpiece which automatically keeps the laser beam aligned as the angle of the handpiece is changed.

It is a further object of this invention to provide such a variable angle surgical laser handpiece in which the deflection device is automatically rotated at a different rate than the handpiece to keep the laser beam aligned.

It is a further object of this invention to provide such a variable angle surgical laser handpiece which is relatively simple and inexpensive.

It is a further object of this invention to provide such a variable angle surgical laser handpiece which is small and compact in keeping with the size of the handpiece.

It is a further object of this invention to provide such a variable angle surgical laser handpiece which can be locked at a particular angle.

The invention results from the realization that a truly compact, safe and effective variable angle surgical laser handpiece can be achieved with a control mechanism that moves a deflection member about a rotational axis at one half the angular motion of the movable member which rotates about the same axis so that the laser beam stays aligned with the passages through the members and the output port in the movable member, automatically, through the full range of rotation of the movable member.

This invention features a variable angle surgical laser handpiece including a fixed member and a movable member rotatably mounted to the fixed member for rotation about a rotation axis, through a range of rotational angles. There is a passage through the members for transmitting a laser beam and a port in the movable member for delivering the laser beam to a surgical target. A deflection device rotatably mounted on the rotation axis directs the laser beam from the fixed member through the movable member and port. A control mechanism constrains rotation of the reflection device to one half the rotational angle of the movable member to maintain the alignment of the laser beam with the passage and port throughout the range of rotation of the movable member.

In a preferred embodiment the deflection device may be a reflection element. The control mechanism may include a locking means for locking the movable member at selected positions in its range of rotation. The control mechanism may include a first gear device for rotation with the movable member, a second device for rotation with the deflection device, and an actuator gear device for interconnecting the first and second gear devices. The first and second gear devices may include first and second pinions, respectively, and the actuator gear device may be a double rack having a rack associated with each pinion. The first pinion may have a predetermined radius and the second pinion has a radius which is twice the predetermined radius. The first gear device may include a central gear, the actuator gear device may include a planetary ring gear and the second gear device may include an idler gear engaged with the central gear and the planetary ring gear. The idler gear may include an actuator element for controlling motion of the deflection device. The control mechanism may include a first curved surface for rotation with the movable member, a second curved surface for rotation with the deflection device and a linear actuator device for introducing equal linear motion to both the curved surfaces. The first surface may have a predetermined radius and the second surface has a radius which is twice that of the first surface. The control mechanism may include a first guide associated with the movable member, a second guide associated with the fixed member and intersecting with the first guide, and an actuator follower constrained by the guides for controlling motion of the deflection device. The guides constrain the actuator follower to a path in which the deflection device is constrained to rotate at half the angular speed of the movable member.

DISCLOSURE OF PREFERRED EMBODIMENT Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

Fig. 1 is a three-dimensional view of a CO₂ surgical laser system employing the handpiece of this invention;

Fig. 2 is an enlarged view employing the handpiece of this invention and a portion of the articulated optical arm which carries it; Figs. 3A-C are ray diagrams which illustrate the need for the deflection device to rotate at one half the angular rotation of the movable member of the handpiece in order to maintain alignment of the laser beam;

Fig. 4 is a schematic sectional side elevational view with portions broken away of a variable angle handpiece according to this invention using a rack and pinion control mechanism; Figs. 5A-C are schematic sectional side elevational views with portions broken away showing the operation of the rack and pinion gears of Fig. 4 to constrain the deflection device to move at half the angular rotation of the movable member;

Fig. 6 is a diagrammatic view of an alternative gearing mechanism according to this invention; Fig. 7 is a schematic three-dimensional view with portions shown in phantom of another construction of the variable angle handpiece according to this invention using partially stiff links and curved surfaces for the control mechanism;

Fig. 8 is a schematic diagram explaining the operation of the handpiece of Fig. 7; Figs. 9A-C are schematic side elevational views illustrating the operation of the mechanism of Fig. 7 which constrain the deflection device to move at half the angular rotation of the movable member;

Fig. 10 is a schematic sectional side elevational view with portions broken away and parts shown in phantom of another construction of a variable angle handpiece according to this invention which has a control mechanism utilizing intersecting guideways and a follower to constrain the rate of motion of the deflection device with respect to the motion of the movable member;

Figs. 11A-C are schematic side elevational views illustrating the operation of the mechanism of Fig. 10 which constrains the movement of the deflection device to one half the angular rotation of that of the movable member; Fig. 12 is an enlarged detailed view showing the intersecting guides and the actuator pin that control the movement of the deflection device;

Fig. 13 is a depiction of the construction of the curve on the movable member of Fig. 12 which defines the locus of motion of the center of the actuator pin plotted in accordance with the values in Table I of the specification; and Fig. 14 is a schematic diagram of the angles and distances used to calculate the values in Table I from which the curve of Fig. 13 is constructed. There is shown in Fig. 1 a surgical laser system 10 including a power supply 12 and control panel 14 for operating CO₂ laser 16 whose output beam is directed through articulated arm 18 to handpiece 20. Handpiece 20, Fig. 2, may be directed to a lens unit 22 including a lens for focusing the laser beam. Handpiece 20 includes a fixed member, barrel 24, and a movable member, barrel 26, which rotate about axis 28. Movable barrel 26 includes an aperture port 30 through which laser beam 32 exits. The distal end of movable barrel 26 includes a contacting surface 34 for contacting the wall of the heart to be perforated by the laser beam in transmyocardial revascularization (TMR). The contacting wall is made relatively large and flat to minimize the contact pressure between it and the heart wall and is flat with rounded edges to minimize interference with the heart. Contacting wall 34 typically includes a textured surface such as a knurling for preventing slipping or skidding of the contacting surface 34 with respect to the heart wall during surgery. An operator device 35 mounted on the proximal end of handpiece 20 is optionally provided to enable the surgeon to rotate the movable barrel 26 relative to the fixed barrel 24 from that remote location rather than having to actually grip the two barrels with his hands to rotate them. When movable barrel 26 is rotated with respect to fixed barrel 24, ordinarily the deflection device such as mirror 36 shown in phantom, would rotate with the movable barrel 26. However, this is unacceptable for if mirror 36 should move equally with movable barrel 26 the laser beam 32 which moves through passage 38 into fixed barrel 24 and passage 40 in movable barrel 26 would no longer be aligned with passage 40 in movable barrel 26 and would not exit port 30. To maintain the proper alignment, mirror 36 actually must move at one half the angular rate as does movable barrel 26.

This can be seen from Figs. 3A-C. In Fig. 3 A the laser beam in fixed barrel 24 has been designated 32a while the same beam exiting from movable barrel 26 has been labeled 32b for easy discussion. In Fig. 3A, with movable barrel 26 at 90° to fixed barrel 24, mirror 36 is at a 45° angle to the incoming laser beam 32a. Its angle of incidence I is therefore 45° with respect to the normal N of the surface of mirror 36. The angle of reflection R of course is equal at 45°. However, in Fig. 3B, when movable barrel 26 has been rotated 30° clockwise to the 120° position it can be seen that to have the incoming laser beam 32a exit properly as beam 32b through passage 40 and port 30, mirror 36 has been rotated only 15°. That is, where it was at an angle I of 45°, Fig. 3 A, the angle I now equals 60°. It has moved the mirror 15° while movable barrel 26 moved 30°. The mirror must move at half the rate of member 26 in order to keep beam 32b aligned with passage 40 in port 30. This is confirmed with respect to Fig. 3C wherein movable barrel 26 has been moved counterclockwise 30° to the 60° position. Now it can be seen that the angle I that mirror 36 makes with respect to incoming beam 32a is 30°, that is, 15° less than I for the original 90° position of barrel 26. Thus when movable barrel 26 has been moved 30° counterclockwise from the 90° position of Fig. 3 A to the 60° position of Fig. 3C, the mirror must be moved only 15° in that direction. In every case mirror 36 must move at half the rate or must be moved half the distance or must move at half the speed of the movable member or barrel 26.

The control mechanism 50, Fig. 4, of variable angle handpiece 20a according to this invention may include a rack and pinion mechanism including a double rack slide 52 including an upper rack 54 and a lower rack 56 which are slidably fixed to the fixed barrel 24. Engaged with rack 54 is pinion gear 58 which is centered at rotational axis 28, the rotational axis of mirror 36, and has a radius R. A second pinion gear 60 is also centered at rotational axis 28 coincident with that of mirror 36 and has a radius of 2R. Pinion gear 58 rotates movable member 26. Pinion gear 60 rotates mirror 36. Double rack 52 is fixed to slide along fixed barrel 24. It may do this because it is driven by pinion gears 58 and 60 when the surgeon grips movable barrel 26 and moves it, or double rack 52 may be connected by link 62, shown in phantom, to a control mechanism 35, which may for example be a simple slide button. Provision may be made to lock the rack and pinion relationship at any point by using locking mechanism 66, Fig. 4, including threaded stud 68 fixed to link 62 and threaded nut 64 so that when nut 64 is screwed against barrel 24 the rack and pinion are locked. The operation of rack and pinion mechanism 50 that effects the half-speed rotation of mirror 36 with respect to movable barrel 26 is illustrated in Figs. 5A, B and C, where in Fig. 5 A it can be seen that with movable barrel 26 at 60° mirror 36 is at angle I of 30° to beam 32a with respect to the normal of the surface of mirror 36. In Fig. 5B with movable barrel 26 at 90° and movable member 26 having moved 30° clockwise to the 90° position, mirror angle I has increased 15° to 45°. In Fig. 5C, where movable barrel 26 has moved an additional 30° clockwise to the 120° position it is apparent that mirror angle I has moved only an additional 15° to the 60° position, so that in each case as movable barrel 26 moved through a predetermined angular rotation, in this case 30°, the mirror moved at only half that rate through an angle of 15°. Another control mechanism, gear train 80, Fig. 6, which can effect the same relative rotation, may include a planetary ring gear 82 which is fixed to fixed barrel 24, a central gear 84 which is fixed to movable barrel 26, and an idler gear 86 which engages planetary ring gear 82 and central gear 84, which has an actuating pin 88 that constrains the movement of mirror 36. Central gear 84 would have a radius 2R while idler gear 86 would have a radius of simply R. Another control mechanism 90, Fig. 7, employed in variable angle handpiece 20b according to this invention may include two curved camming surfaces, one of radius R 92, and the other of radius 2R, 94, both of which are pivoted for rotation about axis 28, the axis of rotation of mirror 36. Curved surface 92 has attached to it a partially flexible, partially stiff element 96, and there is a similar element 98 fixed to curved surface 94. Elements 96 and 98, for example, may each be constructed of a metal band such as those used in a conventional carpenter's steel measurement tape. Elements 96 and 98 can be pushed and pulled while displaying some degree of stiffness in the longitudinal direction yet can easily deflect and conform to the curved surfaces 92 and 94 as they wrap around it. Elements or bands 96 and 98 may be fixed together such as at yoke 100 and connected to an operator line which for example could be connected to control 35, Fig. 2, or they may be fixed together at some other point 104 and the bands ended there in designs wherein the surgeon is expected to manipulate the angle of the movable barrel 26 with respect to the fixed barrel 24 simply by gripping movable barrel 26 and rotating it manually about rotational axis 28. The concept of operation of control mechanism 90 is shown in Fig. 8. When operator 102 is moved to the right as indicated by arrow 104, the yoke 100 moves from position 106 to position 108 a fixed linear distance. The connection points 110 and 112 of elements 96 and 98 to curved surfaces 92 and 94, respectively, are then initially at position 106'. The movement of yoke 100 from position 106 to position 108 moves points 110 and 112 from their points along position 106' to new points 110', 112' along position 108'. While both points 110 and 112 have been moved an equal linear distance it can be seen that because of the fact that surface 92 has a radius of only R while the surface 94 has a radius of 2R, point 112 will have moved only the angle φ whereas point 110 will have moved through an angle of 2φ. The application of this may be better understood with respect to Figs. 9A, B and C, where it can be seen that as the movable barrel 26 moves in 30° increments from a 120° position to a 90° position and then a 60° position in Figs. 9A, B and C, the mirror angle I moves in 15°increments from 60° to 45° to 30°: that is, at half the angular rotational rate of movable barrel 26. In this case, the larger of the two surfaces 94 is fixed to mirror 36 while the smaller of the two surfaces 92 is fixed to the movable member or barrel 26. In yet another construction control mechanism 120, Fig. 10, in handpiece 20c includes a pair of straight slots 122, 124 in fixed barrel 24 and a pair of curved slots 126, 128 in the movable barrel 26 which intersect and guide actuator pin 130 to constrain the movement of mirror 36 to move at half the rate of movable barrel 26 so that beam 32b will stay aligned with passage 40 and port 30 throughout the range of rotational movement of movable barrel 26. The operation of control mechanism 120 to constrain mirror 26 to rotate at half the rate of movable barrel 26 is illustrated in Figs. 11 A, B and C. When movable barrel 26 is at the 60° position, Fig. 11A, mirror angle I is equal to 30°. When movable 26 is moved 30° to the 90° position of Fig. 11B it can be seen that mirror angle I is increased only half that, or 15°, to 45°, and once again, when movable barrel 26 has been moved 30° from the 90° position to the 120°, Fig. 11C, it can be seen that mirror angle I has increased another 15° from 45° to 60°.

The construction of the curved guides 126 and 128 is shown in greater detail in Fig. 12. The locus of points described by actuator pin 130 which constrains the movement of mirror 36, is defined by identical curve guides 126 and 128 which ensure that mirror 36 will rotate about axis 28 at half the rate of rotation of movable member 26. The construction of the locus of points of curve guides 126 and 128 with respect to axes E and F in Fig. 12 is constructed, as shown in Fig. 13, by plotting the points obtained in Table I. TABLE I

The values of Table I were derived from angles and distances portrayed in Fig. 14 assuming a 1 mm thickness for mirror 36, a .040 diameter for actuator pin 130 with the pin centered at .15 from the beam axis 32. In this consideration s = .06 which is 1 mm plus the radius of the pin diameter, and r= .15. The derivation is as follows.

FIND E&F IN TERMS OF r, s, a

A' = r-A cosα = A/s; A = scosα A' = r-scosα B' = C-B sinα = B/s; B = ssinα B' = c-ssinα

r _ssinα

N, r²+( r-scosα -ssinα) _β/=r_zscosα_ tanα tanα

tanθ=— =

B' r-scosα -ssinα tanα

sinφ=£'/D

cosφ=F/

sin [2α -tan^_1 ( ) ] r-scosα -s „si • _nα„ tanα

Although specific features of this invention are shown in some drawings and not others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention.

Other embodiments will occur to those skilled in the art and are within the following claims:

Although a few mechanisms have been shown to implement the invention, these are illustrative only as other mechanisms and arrangements may be used to the same effect and are included in the scope of the appended claims. For example, although the control mechanism is illustrated as including gears or cams or other drive devices could be used as well, e.g., friction drives. What is claimed is:

Claims

1. A variable angle surgical laser handpiece comprising: a fixed member and a movable member rotatably mounted to said fixed member for rotation about a rotation axis, through a range of rotational angles; a passage through said member for transmitting a laser beam; a port in said movable member for delivering the laser beam to a surgical target; a deflection device rotatably mounted on said rotation axis for directing the laser beam from the fixed member through said movable member and port; and a control mechanism for constraining rotation of said deflection device to one half the rotational angle of said movable member to maintain the alignment of the laser beam with said passage and port throughout the range of rotation of the movable member.

2. The variable angle surgical laser handpiece of claim 1 in which said deflection device is a reflection element.

3. The variable angle surgical laser handpiece of claim 1 in which said control mechanism includes locking means for locking said movable member at selected positions in its range of rotation.

4. The variable angle surgical laser handpiece of claim 1 in which said control mechanism includes a first gear device for rotation with said movable member, a second gear device for rotation with said deflection device and an actuator gear device for interconnecting said first and second gear devices.

5. The variable angle surgical laser handpiece of claim 4 in which said first and second gear devices include first and second pinions, respectively, and said actuator gear device is a double rack having a rack associated with each pinion.

6. The variable angle surgical laser handpiece of claim 5 in which said first pinion has a predetermined radius and said second pinion has a radius which is twice said predetermined radius.

7. The variable angle surgical laser handpiece of claim 4 in which said first gear device includes a central gear, said actuator gear device includes a planetary ring gear and said second gear device includes an idler gear engaged with said central gear and said planetary ring gear.

8. The variable angle surgical laser handpiece of claim 7 in which said idler gear includes an actuator element for controlling motion of said deflection device.

9. The variable angle surgical laser handpiece of claim 1 in which said control mechanism includes a first curved surface for rotation with said movable member, a second curved surface for rotation with said deflection device and a linear actuator device for introducing equal linear motion to both said curved surfaces.

10. The variable angle surgical laser handpiece of claim 9 in which said first surface has a predetermined radius and said second surface has a radius which is twice that of said first surface.

11. The variable angle surgical laser handpiece of claim 1 in which said control mechanism includes a first guide associated with said movable member, a second guide associated with said fixed member and intersecting with said first guide, and an actuator follower constrained by said guides for controlling motion of said deflection device.

12. The variable angle surgical laser handpiece of claim 11 in which said guides constrain said actuator follower to a path in which the deflection device is constrained to rotate at half the angular speed of the movable element.

13. A variable angle surgical laser handpiece comprising: a fixed member and a movable member rotatably mounted to said fixed member for rotation about a rotation axis, through a range of rotational angles; a passage through said member for transmitting a laser beam; a port in said movable member for delivering the laser beam to a surgical target; a deflection device rotatably mounted on said rotation axis for directing the laser beam from the fixed member through said movable member and port; and a control mechanism including a first gear device for rotation with said deflection device and an actuator gear device for interconnecting said first and second gear devices.

14. A variable angle surgical laser handpiece comprising: a fixed member and a movable member rotatably mounted to said fixed member for rotation about a rotation axis, through a range of rotational angles; a passage through said members for transmitting a laser beam; a port in said movable member for delivering the laser beam to a surgical target; a deflection device rotatably mounted on said rotation axis for directing the laser beam from the fixed member through said movable member and port; and a control mechanism including a first curved surface for rotation with said movable member, a second curved surface for rotation with said deflection device and a linear actuator device for introducing equal linear motion to both said curved surfaces.

15. A variable angle surgical laser handpiece comprising: a fixed member and a movable member rotatably mounted to said fixed member for rotation about a rotation axis, through a range of rotational angles; a passage through said members for transmitting a laser beam; a port in said movable member for delivering the laser beam to a surgical target; a deflection device rotatably mounted on said rotation axis for directing the laser beam from the fixed member through said movable member and port; and a control mechanism including a first guide associated with said movable member, a second guide associated with said fixed member and intersecting with said first guide, and an actuator follower constrained by said guides for controlling motion of said deflection device.