POSITIONING DEVICE AND LIGHT PROCESSING DEVICE COMPRISING SUCH A POSITIONING DEVICE

Description

[0001] The present invention relates to a positioning device for positioning an object in a positioning plane and to a light processing device comprising such a positioning device. Such a light processing device can be used in particular for performing laser eye surgery.

[0002] The term "laser eye surgery" refers to a special eye surgery or laser eye surgery treatment in which refractive vision impairment can be corrected by removing the cornea. In such visual impairments, the light is deflected by the curvature of the cornea and the lens and projected into the eye. The focus is not exactly on the fovea, the area of ​​sharpest vision on the retina, but rather in front of or behind it.

[0003] During laser eye surgery, a very thin layer of the cornea is first cut away and folded back, which then serves as protection and promotes healing. A laser then ablates the surface of the cornea, changing the optical properties of the eye and restoring the corneal refractive power to its optimal level.

[0004] A cataract is a clouding of the eye's natural lens, usually caused by age. Light rays can no longer focus on the retina within the eye. This leads to increased sensitivity to light and glare, blurred vision, and sometimes double vision or colors appear gray. During laser eye surgery for cataracts, the clouded natural lens is removed and replaced with a clear intraocular lens. To access the clouded lens, a femtosecond laser is used to create a small incision in the eye. The femtosecond laser then creates a circular opening in the anterior lens shell. The nucleus located in the posterior chamber of the eye is then crushed and aspirated. The remaining lens shell then serves as a "natural support" for the new intraocular lens.

[0005] During these laser eye surgery procedures, the laser beam must be guided with high precision along a predetermined path or trajectory across the patient's cornea. Errors in the positioning and duration of the laser beam on the patient's cornea can not only adversely affect the treatment outcome but also cause serious damage to the patient's eye.

[0006] If arbitrary trajectories or movement paths in a plane are to be followed, two linear stages (X and Y) are usually used, which are arranged at right angles to each other and the Y stage is connected to the moving part of the X stage. A circular trajectory can be achieved by means of a sinusoidal speed profile of the first axis (X) and a sinusoidal speed profile of the second axis (Y) that is phase-shifted by 90°. During continuous circular trajectory travel, both axes (X and Y) must each change direction twice, i.e. the full circle has a total of four turning points. Due to physical conditions (inertia, backlash, finite sensor resolution, finite controller speed, etc.), a certain dead time occurs at the turning points, i.e. the change of direction does not occur infinitely quickly, but there is a phase in which the respective axis is at a standstill.Due to this dead time, a dynamic position error (following error) results, ie the full circle has a total of four errors.

[0007] The publication FISHER Charles, [et al]: Cobra: A two-degree of freedom fiber optic positioning mechanism, IEEE Aerospace conference, IEEE, 2009, pp. 1-11 discloses another positioning device.

[0008] The document discloses a grinding wheel comprising: two rotary drives with different diameters and an object holder for holding the object, wherein the object holder is coupled to a first of the two rotary drives, which in turn is coupled to the second of the two rotary drives, so that the object holder is rotatable about the parallel and offset rotation axes of the two rotary drives and thus adjustable in the positioning plane.

[0009] The invention is based on the object of providing a positioning device for positioning an object in a positioning plane that minimizes the position error (following error) during continuous circular path travel, in contrast to two linear adjusters (X and Y) arranged at right angles to each other. Furthermore, the invention is based on the object of providing a light processing device to reduce the dynamic position error (following error) known from linear adjusters (X and Y) arranged at right angles to each other when traversing a circular path with the laser beam, in particular on the cornea of ​​a patient.To achieve this object, the present invention provides the positioning device for positioning an object in a positioning plane according to claim 1, which comprises: two rotary drives with different diameters and an object holder for holding the object, wherein the object holder is coupled to a first of the two rotary drives, which in turn is coupled to the second of the two rotary drives, such that the object holder can be rotated about the parallel and offset rotation axes of both rotary drives and can thus be adjusted in the positioning plane. The invention enables the traversing of any trajectory (movement path) in general, as well as the precise traversing of a circular trajectory in particular. The invention eliminates the need for error-prone turning points. Circular trajectories can be traversed continuously and precisely.The absence of turning points and thus dead times allows for a reduction in dynamic positioning errors during circular trajectories. Unlike a single-axis rotary system, however, not only circular trajectories but also arbitrary trajectories can be achieved.

[0010] The first rotary drive and / or the second rotary drive are ring-shaped. With this design, the object holder can be arranged within the ring opening or aperture of the first rotary drive, allowing the positioning device to be constructed extremely compactly.

[0011] Advantageous further developments of the invention are the subject matter of the subclaims.

[0012] It can be beneficial if the first rotary drive has a smaller diameter than the second. This makes it particularly easy to control the position of the specimen holder.

[0013] It may be advantageous if a movement path of the object holder extending around the rotation axis of the first rotary drive encloses or intersects the rotation axis of the second rotary drive. In this embodiment, the object holder can be moved to any point of the positioning plane within a circle that corresponds to the movement path of the object holder around the rotation axis of the second rotary drive by appropriately actuating the rotary drives.

[0014] It can be useful if the diameter of a (first) movement path of the object holder running around the rotation axis of the first rotation drive is at least half the maximum diameter of a (second) movement path of the object holder running around the rotation axis of the second rotation drive. By adjusting the distance of the object holder from the rotation axis of the second rotation drive—by actuating the first rotation drive—the diameter of the second movement path of the object holder can be specifically adjusted—from zero to twice the diameter of the first movement path of the object holder.

[0015] It may be useful if the rotation directions and / or rotation speeds of the rotary drives can be controlled separately from one another. This allows the object holder to, in principle, follow any trajectory within the positioning plane and within the second movement path of the object holder around the rotation axis of the second rotary drive. Preferably, the first rotary drive and / or the second rotary drive are embodied as piezoelectric rotary drives.

[0016] However, it can also be helpful if each annular rotary drive has two rings that can rotate relative to each other, one of which is designed as a stator ring and the other as a rotor ring. This design proves to be particularly compact and cost-effective to manufacture.

[0017] It may also prove useful if the stator ring of the first rotary drive is coupled in a rotationally fixed manner to the rotor ring of the second rotary drive, preferably via a detachable coupling.

[0018] It may be useful to arrange the object holder on the inner circumference of the (rotor ring of the) first rotary drive. This design also proves to be particularly compact.

[0019] A further aspect of the present invention relates to a light processing device according to claim 10, comprising a positioning device according to one of the preceding claims and a light-directing element which is arranged on or in the object holder of the positioning device and is adjustable in the positioning plane by means of the positioning device in order to direct a light beam, in particular a laser beam, onto an object to be processed by the light beam. With the light processing device, a laser beam can be directed particularly precisely along circular paths onto an object to be processed or over its surface. For example, very powerful lasers are required for eye laser surgery, which are heavy and take up a large volume.Regardless of such limitations, the light processing device according to the invention enables particularly gentle and safe laser eye surgery for cataracts or refractive visual impairments by changing a patient's corneal curvature, because only the light-directing element needs to be moved to deflect the laser beam. The light-directing element can be designed, for example, as a mirror, prism, light guide, lens, objective, or the like.

[0020] It may also be advantageous if the light-guiding element is arranged and / or alignable on or in the object holder of the positioning device in such a way that the light beam runs parallel to the rotation axes of both rotary drives. This embodiment allows for particularly precise alignment of the light beam, which improves the processing result.

[0021] It may prove useful if the light beam passes through the ring opening of the first rotary drive and / or through the ring opening of the second rotary drive. This embodiment allows, for example, beam paths to be directed through the system.

[0022] It may also be useful for the light-guiding element to be the light-emitting part of a laser, preferably a femtosecond laser. Such a laser is particularly suitable for the treatment of cataracts or refractive-based visual impairments.

[0023] A further aspect relates to the use of the light processing device according to one of claims 10 to 13 for the treatment of cataracts or a refractive-based visual impairment by acting on the cornea of ​​a patient by means of the light beam or laser beam.

[0024] Yet another aspect relates to a method for laser eye surgery using the light processing device according to any one of claims 10 to 13, comprising the steps: Arranging the light processing device at a distance from the cornea of ​​a patient, preferably such that the positioning plane of the positioning device is aligned exactly or substantially perpendicular to a normal to the patient's cornea; adjusting the light-guiding element arranged in the object holder of the positioning device in the positioning plane by means of the first rotary drive and / or the second rotary drive, so that the light beam guided by the light-guiding element follows an at least partially circular and / or an at least partially curved track and / or an at least partially straight track on the patient's cornea, in order to change the curvature of the patient's cornea.

[0025] It may prove useful to combine the positioning device with one or more linear actuators or linear stagers to facilitate the traversing of linear trajectories.

[0026] Further preferred embodiments result from combinations of the features disclosed in the claims, the drawings and the description. Terms and definitions trajectory

[0027] The trajectory of the object holder around the rotation axis of the rotary drive corresponds to the imaginary circle that the object holder describes during one complete rotation around the rotation axis of the rotary drive. Object recording

[0028] The term object holder refers to a holder or holder for an object to be moved by the positioning device. Positioning level

[0029] The positioning plane is the plane in which the specimen holder can be moved by actuating the rotary drives. The positioning plane extends perpendicular to the rotation axes of both rotary drives.

[0030] Light-guiding element: A light-guiding element is an element capable of directing a light beam. The light-guiding element is preferably designed as a mirror, prism, lens, light guide, objective, or the like. Short description of the characters

[0031] They show: Fig. 1 a schematic and perspective view of a light processing device according to the invention with a positioning device according to the invention, which has two annular rotary drives with different diameters. Figure 2 a schematic and perspective view of the light processing device according to Figure 1in an eye laser surgical treatment, wherein a light-guiding element is adjusted by the positioning device by actuating the two rotary drives in the positioning plane in order to guide the light beam guided by the light-guiding element along an at least partially circular trajectory over the cornea of ​​a patient. Fig. 3 a schematic and perspective view similar to the Figure 1 . Fig. 4 a schematic and perspective view similar to the Figure 2 from a different perspective. Fig. 5 in views (a) to (d) various stages of an eye laser surgical treatment using the light processing device according to one of the Figures 1 to 4Figure 6 is a schematic plan view along the rotation axes of both rotation drives perpendicular to the movement paths of the object holder around each of the two rotation axes according to a preferred embodiment of the positioning device according to the invention. Detailed description of the preferred embodiment

[0032] The preferred embodiment of the invention, which is described in detail below with reference to the accompanying figures, relates to a light processing device in the form of an ophthalmic laser surgical instrument, comprising a light-guiding element in the form of a mirror or light guide and a positioning device 1 according to the invention with two rotary drives 2, 3 of different diameters and an object holder 4 in which the light-guiding element is arranged. This light-guiding element is designed to direct a laser beam 5 for ophthalmic laser surgical treatment onto the cornea 6 of a patient, wherein the light-guiding element is adjustable in the positioning plane by means of the positioning device 1. In the present case, the light-guiding element is the light-emitting part of a femtosecond laser for performing laser-assisted eye surgery.

[0033] The positioning device 1 according to the invention serves to position the light-guiding element in a positioning plane. The object holder 4, which accommodates the light-guiding element, is coupled to the first rotary drive 3 with a smaller diameter, which in turn is preferably releasably coupled to the second rotary drive 2 with a larger diameter via a coupling 23, so that the object holder 4 can be rotated about the parallel and offset rotation axes A2, A3 of both rotary drives 2, 3 and thus adjusted in the positioning plane.

[0034] As shown in Figure 6, a movement path B3 of the object holder 4 running around the rotation axis A3 of the first rotation drive 3 intersects the rotation axis A2 of the second rotation drive 2. Accordingly, the diameter of the movement path B3 of the object holder 4 running around the rotation axis A3 of the first rotation drive 3 is exactly half the size of the maximum diameter of a movement path B2 of the object holder 4 running around the rotation axis A2 of the second rotation drive 2. This means that the object holder 4 or the light directing element arranged thereon can reach any position in the positioning plane that is located within the movement path B2 of the object holder 4 running around the rotation axis A2 of the rotation drive 2 with a larger diameter.

[0035] Because the directions of rotation and rotation speeds of the rotation drives 2, 3 can be controlled separately from one another, the object holder 4 can travel any trajectory within the positioning plane, in particular circular, curved or straight sections thereof.

[0036] In the present embodiment, each of the two rotary drives 2, 3 is annular and has two rings 21, 31; 22, 32 that can rotate relative to one another, one of which is designed as a stator ring 21, 31 and the other as a rotor ring 22, 32. The stator ring 31 of the first rotary drive 3 is preferably coupled in a rotationally fixed manner to the rotor ring 22 of the second rotary drive 2 via the releasable coupling 23, and the object holder 4 is arranged on an inner circumference of the rotor ring 32 of the first rotary drive 3.

[0037] The light-guiding element is arranged in the object holder 4 of the positioning device 1 such that the laser beam 5 runs parallel to the rotation axes A2, A3 of both rotary drives 2, 3. The laser beam 5 is guided through the ring opening of both rotary drives in order to strike a target object 6 arranged underneath in the operating state (see. Fig. 2 , 4 , 5 ).

[0038] According to a method for laser eye surgery, the light processing device according to the invention is arranged at a distance from the cornea 6 of a patient, so that the positioning plane of the positioning device 1 is ideally aligned exactly or substantially perpendicular to a normal to the cornea 6 of the patient (cf. Fig. 2 , 4 , 5). Subsequently, the light-guiding element arranged in the object holder 4 of the positioning device 1 is adjusted in the positioning plane by actuating both rotation drives, so that the laser beam 5 guided by the light-guiding element follows a track on the patient's cornea 6, which can contain circular, curved or straight sections in order to change the curvature of the patient's cornea or to make cuts in the patient's cornea. Individual stages of this process are shown in views (a) to (d) of the Fig. 5 shown.

[0039] By rotating or adjusting the first rotary drive 3, different circle diameters can be specifically set. By rotating or adjusting the second rotary drive 2, circular paths with the previously set circle diameter can be continuously traversed. By rotating the first and second rotary drives 2, 3 together, any desired trajectory can be traversed. List of reference symbols

[0040] 1Positioning device 2Second rotation drive (large diameter) 3First rotation drive (small diameter) 4Object holder 5Beam path or light beam or laser beam 6Target object or cornea 21Stator ring of the second rotation drive (large diameter) 22Rotor ring of the second rotation drive (large diameter) 23Coupling section 31Stator ring of the first rotation drive (small diameter) 32Rotor ring of the first rotation drive (small diameter) A2Rotation axis of the second rotation drive (large diameter) A3Rotation axis of the first rotation drive (small diameter) B2Movement path of the object holder around the rotation axis A2 B3Movement path of the object holder around the rotation axis A3

Claims

1. Positioning device (1) for positioning an object in a positioning plane, comprising: two rotation drives (2, 3) having different diameters and an object receiver (4) for receiving said object, where said object receiver (4) is coupled to a first of said two rotation drives (3), which in turn is coupled to the second of said two rotation drives (2), so that said object receiver (4) can be rotated about the axes of rotation (A2, A3) of both rotation drives (2, 3), that are arranged parallel and offset from one another, and is thereby adjustable in said positioning plane, characterized in that said first rotation drive (3) and / or said second rotation drive (2) is / are ring-shaped.

2. Positioning device (1) according to claim 1, characterized in that said first rotation drive (3) has a smaller diameter than said second rotation drive (2).

3. Positioning device (1) according to one of the preceding claims, characterized in that a path of motion (B3) of said object receiver (4) extending around said axis of rotation (A3) of said first rotation drive (3) encloses or intersects said axis of rotation (A2) of said second rotation drive (2).

4. Positioning device (1) according to one of the preceding claims, characterized in that the diameter of a path of motion (B3) of said object receiver (4) extending around said axis of rotation (A3) of said first rotation drive (3) is at least half as large as the maximum diameter of a path of motion (B2) of said object receiver (4) extending around said axis of rotation (A2) of said second rotation drive (2).

5. Positioning device (1) according to one of the preceding claims, characterized in that the directions of rotation and / or speeds of rotation of said rotation drives (2, 3) can be controlled separately from one another.

6. Positioning device (1) according to one of the preceding claims, characterized in that each ring-shaped rotation drive (2, 3) comprises two rings (21, 31; 22, 32) rotatable relative to one another, one of which is formed as a stator ring (21, 31) and the other as a rotor ring (22, 32).

7. Positioning device (1) according to one of the preceding claims, characterized in that said stator ring (31) of said first rotation drive (3) is coupled in a rotationally fixed manner to said rotor ring (22) of said second rotation drive (2), preferably by way of a releasable coupling (23).

8. Positioning device (1) according to one of the preceding claims, characterized in that said object receiver (4) is arranged on an inner circumference of said first rotation drive (3).

9. Light processor comprising a positioning device (1) according to one of the preceding claims as well as a light-directing element which is arranged on said object receiver (4) of said positioning device (1) and can be adjusted in said positioning plane by way of said positioning device (1) in order to direct a light beam (5) onto an object to be processed by said light beam (5).

10. Light processor according to claim 9, characterized in that said light-directing element is arranged and / or alignable on said object receiver (4) of said positioning device (1) such that said light beam (5) extends parallel to said axes of rotation (A2, A3) of both rotation drives (2, 3).

11. Light processor according to one of the claims 9 or 10 in combination with one of the claims 6 to 9, characterized in that said light beam (5) is guided through the ring opening of said first rotation drive (3) and / or through the ring opening of said second rotation drive (2).

12. Light processor according to one of the claims 9 to 11, characterized in that said light-directing element is the laser light-emitting part of a laser, preferably a femtosecond laser.