BRIEF DESCRIPTION OF THE DRAWINGS
A design of the present invention is explained below with the aid of an example. The example of the design is illustrated by the following enclosed Figures:
FIG. 1 shows a block diagram that represents schematically an ophthalmologic apparatus used in treating an eye by means of a focused pulsed laser beam.
FIGS. 2
a, 2b, 2c and 2d respectively show a block diagram that illustrates schematically a design variant of the ophthalmologic apparatus used in treating an eye by means of a focused pulsed laser beam.
FIG. 3
a shows a pulse processing area, formed by a femtosecond laser pulse on the focal surface and having a circular area boundary in accordance with the prior art.
FIG. 3
b shows a number of pulse processing areas succeeding one another along a processing line and respectively having a circular area boundary in accordance with the prior art.
FIG. 4
a shows a pulse processing area formed by a femtosecond laser pulse on the focal surface and having an area boundary deviating from the circular shape.
FIG. 4
b shows a number of pulse processing areas succeeding one another along a straight processing line and having an area boundary deviating from the circular shape, and a longitudinal alignment transverse to the processing line.
FIG. 4
c shows an alignment of a pulse processing area having an area boundary deviating from the circular shape along a curved processing line.
FIG. 5
a shows a number of pulse processing areas succeeding one another along a straight processing line and having an area boundary deviating from the circular shape, and a longitudinal alignment along the processing line.
FIG. 5
b shows a further alignment of a pulse processing area having an area boundary deviating from the circular shape along the curved processing line.
FIG. 6 shows a number of incision tracks juxtaposed in a row that are respectively formed by pulse processing areas succeeding one another along the straight processing line.
WAYS OF IMPLEMENTING THE INVENTION
In FIGS. 1, 2a, 2b, 2c and 2d, the reference symbol 1 denotes an ophthalmologic apparatus having a laser source 14 and a light projector 11, optically connected to the laser source 14, for the generation and focused projection of a pulsed laser beam L1 for the punctiform breakdown of tissue at a focus F (focal point) in the interior of the eye tissue 21, for example in the cornea. The laser source 14 comprises a femtolaser for generating femtosecond laser pulses that have pulse widths of typically 10 fs to 1000 fs (1 fs=10−15 s). The laser source 14 is arranged in a separate housing or in a common housing with the light projector 11. As illustrated schematically in FIG. 1, the ophthalmologic apparatus 1 comprises positioning means 12 in order to move the focus F of the pulsed laser beam L′ in at least two dimensions x, y of a processing area (coherent or not coherent) in or on the tissue of the eye 3. In a design variant, the positioning means 12 are, however, configured also to move the focus F in a third direction, normal to the two dimensions x, y. In a design variant, the positioning and movement of the focus F is effected solely by an optical scanner module that appropriately deflects the pulsed light beam generated by the laser source 14. In a design variant, in addition to the optical scanner module, the positioning means 12 comprise one or more movement drivers for moving the light projector 11. The positioning means 12 are designed, for example, as in EP 1 486 185 (also incorporated by reference), and in a design variant superpose by means of optical microscans an additional fine movement on the translational movement of the focus caused by the movement of the light projector 11, doing so in accordance with EP 1 627 617. In European patent application No. 05 405 376 (not yet published) there is a description of a scanner module for deflecting a pulsed light beam for the additional fine movement, as well as of an optical transmission system for transmitting the deflected femtosecond laser pulses from the scanner module to the light projector 11 and for superposing the deflected femtosecond laser pulses on the movement of the light projector 11.
Owing to the focused projection of the pulsed laser beam L′, the femtosecond laser pulses respectively form pulse processing areas on the focal surface (that is to say focal plane or convex focal surface). The area boundary of a pulse processing area is defined, for example, by a limit value G for the drop in intensity 1/e2 of the femtosecond laser pulse focused on the focal surface. The area boundary is, for example, defined where the intensity of the irradiated light on the focal surface drops by or to at least the defined limit value G, for example by 60% or to 40%. In FIGS. 3a and 4a, the reference symbols u and v denote the coordinate axes of the focal surface coinciding with the plane of a drawing. As is illustrated in FIG. 3a, a pulse processing area C, produced by a femtosecond laser pulse of a known system, on the focal surface exhibits a circular area boundary c. FIG. 3b shows an incision track 3 that has a number of pulse processing areas C succeeding one another along the straight processing line s. As is to be seen from FIG. 3b, the pulse processing areas (C, which are formed by successive femtosecond laser pulses, have overlap areas A.
As is illustrated in FIG. 1, the ophthalmologic apparatus 1 additionally comprises optical means 13 that are arranged in the schematically illustrated beam path L between the laser source 14 and the exit of the light projector 11. The optical means 13 are configured to influence the radiation intensity, the phase delay time and/or polarity over the beam cross section of the femtosecond laser pulses such that the femtosecond laser pulses form on the focal surface pulse processing areas E with an area boundary e deviating from the circular shape, as is illustrated in FIG. 4a, for example. By comparison with the conventional circular pulse processing areas C, the pulse processing areas E produced by the optical means 13 preferably extend in a longitudinal direction and are compressed in a transverse direction, and have an elliptically or ovally shaped area boundary e, for example. In a design variant, the laser source 14 is configured to generate femtosecond laser pulses with an elliptically or ovally shaped area boundary e deviating from the circular shape (occasioned by a typical Gaussian profile). In this last-named design variant, the optical means 13 are just configured to image or project the femtosecond laser pulses generated by the laser source 14 onto the focal surface in a focused fashion via the light projector 11, in order to produce pulse processing areas E with an elliptically or ovally shaped area boundary (e) on the focal surface.
In order to produce pulse processing areas E deviating from the circular shape, the optical means 13 comprise a polarization modulator, a phase modulator and/or an intensity modulator for modulating the radiation intensity, the phase delay times and/or the polarity over the beam cross section of the femtosecond laser pulses. The optical means 13 comprise, for example, an anamorphotic optical module (for example, movable spherical and/or cylindrical lenses), one or more deformable mirrors, photonic crystals, photonic “bandgap” fibers, diffractive optical modules, lens arrays, polarization filters, spatial polarization plates, λ-half-plates, stops, and/or one or more spatial light modulators, for example LCD arrays or DLP projectors. In the design variant according to FIG. 2a, the optical means 13 are inserted as optical module into the beam path between the laser source 14 and the positioning means 12. The femtosecond laser pulses L1 generated by the laser source 14 are fed to the optical means 13, which modulate the radiation intensity, the phase delay times and/or the polarity over the beam cross section of the femtosecond laser pulses L1 in order to produce noncircular pulse processing areas E. The femtosecond laser pulses L2 generated by the optical means 13 and having a modulated radiation intensity, phase delay time and/or polarity are fed to the positioning means 12. The positioning means 12 deflect the femtosecond laser pulses L2 into at least one scanning direction, and/or move the light projector 11 into one or two further scanning directions. The femtosecond laser pulses L2″ deflected by the positioning means 12 are fed to the light projector 11 for the purpose of focused projection.
In the design variant according to FIG. 2b, the optical means 13 are inserted as optical module into the beam path between the positioning means 12 and the light projector 11. The femtosecond laser pulses L1 generated by the laser source 14 are fed to the positioning means 12, which deflect the femtosecond laser pulses L1 into at least one scanning direction, and/or move the light projector 11 into one or two further scanning directions. The femtosecond laser pulses L1″ deflected by the positioning means 12 are fed to the optical means 13, which modulate the radiation intensity, the phase delay time and/or the polarity over the beam cross section of the femtosecond laser pulses L1″ in order to produce noncircular pulse processing areas E. The femtosecond laser pulses L3 generated by the optical means 13 and having a modulated radiation intensity, phase delay time and/or polarity are fed to the light projector 11 for the purpose of focused projection.
In the design variant according to FIG. 2c, the optical means 13 are inserted as optical module into the beam path between two modules of the positioning means 12, 12′. The femtosecond laser pulses L1 generated by the laser source 14 are fed to the first module of the positioning means 12′, which deflect the femtosecond laser pulses L1 into at least: one scanning direction. The femtosecond laser pulses L1′ deflected by the positioning means 12 are fed to the optical means 13, which modulate the radiation intensity, phase delay time and/or the polarity over the beam cross section of the femtosecond laser pulses L1′ in order to produce noncircular pulse processing areas E. The femtosecond laser pulses L4 generated by the optical means 13 and having modulated radiation intensity, phase delay time and/or polarity are fed to the second module of the positioning means 12, which deflect the femtosecond laser pulses 14 into at least one further scanning direction, and/or move the light projector 11 into one or two further scanning directions. The femtosecond laser pulses L4′ deflected by the second module of the positioning means 12 are fed to the light projector 11 for the purpose of focused projection.
In the design variant according to FIG. 2d, the optical means 13 are integrated in the light projector 11. The femtosecond laser pulses L1 generated by the laser source 14 are fed to the positioning means 12, which deflect the femtosecond laser pulses L1 in at least one scanning direction, and/or move the light projector 11 into one or two further scanning directions. The femtosecond laser pulses L1″ deflected by the positioning means 12 are fed to the optical means 13 in the light projector 11, which modulate the radiation intensity, the phase delay time and/or the polarity over the beam cross section of the femtosecond laser pulses L1″ in order to produce noncircular pulse processing areas E. The femtosecond laser pulses generated by the optical means 13 and having a modulated radiation intensity, phase delay time and/or polarity are projected by the light projector 11 in a focused fashion.
In FIGS. 1, 2a, 2b, 2c and 2d, the reference symbol 15 denotes a control module that is designed as a programmed logic module by means of software and/or hardware. The control module 15 is configured to control the positioning means 12 and the optical means 13. The control module 15 is configured, in particular, to control the optical means 13 in order to align the pulse processing areas E with reference to the processing line s. In a design variant, the control module 15 is, however, configured to control the optical means 13 in order to produce pulse processing areas E having a different shape, deviating from the circular shape. The control of the optical means 13 with regard to the alignment and/or shape of the pulse processing areas E is preferably based on one or more user-specific control values that define the shape of the pulse processing areas E, the size of the overlap areas B, D (see FIG. 5a), or a degree of overlap, and/or the processing pattern.
FIG. 4
b shows an incision track 4 that has a number of pulse processing areas E which succeed one another along the straight processing line s, have an area boundary E in accordance with FIG. 4a deviating from the circular shape, and are aligned such that a longitudinal axis r running in the wider extent of the pulse processing area E respectively lies perpendicular to the processing line s. As is to be seen from FIG. 4b, the pulse processing areas E that are formed by successive femtosecond laser pulses of the same pulse spacing p as in FIG. 3b have smaller overlap areas B than the circular pulse processing areas C in FIG. 3b.
FIG. 4
c shows an alignment of a pulse processing area E that has an area boundary e in accordance with FIG. 4a along a curved processing line s*. As may be seen from FIG. 4c, the pulse processing area E is aligned such that the longitudinal axis r running in the wider extent of the pulse processing area E lies perpendicular to the tangent t to the curved processing line s*, the center point Z of the pulse processing area E corresponding to the point of contact of the tangent t.
FIG. 5
a shows an incision track 5 that has a number of pulse processing areas E, which follow one another along the straight processing line s, have an area boundary e in accordance with FIG. 4a that deviates from the circular shape, and are aligned such that a transverse axis q running in the narrower extent of the pulse processing area E respectively lies perpendicular to the processing line s.
FIG. 5
b shows an alignment of a pulse processing area E, which has an area boundary e in accordance with FIG. 4a, along a curved processing line s*. As may be seen from FIG. 5b, the pulse processing area E is aligned such that the transverse axis q running in the narrower extent of the pulse processing area E lies perpendicular to the tangent t to the curved processing line s*, the center point Z of the pulse processing area E corresponding to the point of contact of the tangent t.
FIG. 6 shows a number of incision tracks 6a, 6b, juxtaposed in a row, in accordance with FIG. 4b. As may be seen from FIG. 6, the pulse processing areas E of the first incision track 6a, along the processing line s, and the pulse processing areas E of the second incision track 6a, along the processing line s′, are phase shifted such that no bridges of tissue are left between the incision tracks 6a, 6b, and the smallest possible overlap areas are formed by the pulse processing areas E of neighboring incision tracks 6a, 6b.
Finally, it is to be stated that the described ophthalmologic apparatus 1 enables a breaking down of eye tissue as a three-dimensional ablation process, the effects illustrated in FIGS. 3a, 3b, 4a, 4b, 4c, 5a, 5b and 6 being respectively illustrated in plan view.
Patent Application
20070282312
