Patent Publication Number: US-8992020-B2

Title: Device for processing eye tissue by means of a pulsed laser beam

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/563,637, filed Nov. 25, 2011, entitled VORRICHTUNG ZUM BEARBEITEN VON AUGENGEWEBE MITTELS EINES GEPULSTEN LASERSTRAHLS, the entire contents of which are hereby incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an ophthalmological device for processing eye tissue by means of a pulsed laser beam. The present invention relates, in particular, to an ophthalmological device comprising a projection optical unit for the focused projection of the laser beam into the eye tissue, and a scanner system disposed upstream of the projection optical unit and serving for the beam-deflecting scanning of the eye tissue with the laser beam. 
     PRIOR ART 
     For processing eye tissue by means of a laser beam, a processing region is scanned with laser pulses by the pulsed laser beam being deflected in one or two scanning directions by means of suitable scanner systems (deflection devices). The deflection of the light beams or of the laser pulses, for example femtosecond laser pulses, is generally performed by means of movable mirrors which are pivotable about one or two scanning axes, for example by means of galvanoscanners, piezoscanners, polygon scanners or resonance scanners. 
     U.S. Pat. No. 7,621,637 describes a device for processing eye tissue, said device having a base station with a laser source for generating laser pulses and a scanner arranged in the base station with movable deflection mirrors for deflecting the laser pulses in a scanning direction. The deflected laser pulses are transmitted via an optical transmission system from the base station to an application head, which moves over a working region in accordance with a scanning pattern by means of a mechanically moved projection optical unit. The deflection in the scanning direction, which is much faster compared with the mechanical movement, is superimposed in the application head onto the mechanical movement of the projection optical unit and thus onto the scanning pattern thereof. A fast scanner system in the base station enables a fine movement of the laser pulses (microscan), which is superimposed onto the scanning pattern of the movable projection optical unit that covers a large processing region, for example the entire eye. 
     Although the known systems make it possible to process simple scanning patterns, for example to cut a tissue flap, this generally being performed as a large area segment with a simple edge geometry, in the case of applications which involve not only making tissue cuts in a substantially horizontally oriented processing area on a common focal area, but also intending to make cuts with a vertical cut component over different focus heights, e.g. cuts that are vertical or run obliquely with respect to the horizontal, the vertical movement of the projection optical unit or at least parts thereof for a vertical variation of the focus and thus of the cut height proves to be too slow for making cuts with a vertical component, that is to say with a variable depth of focus during cutting. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to propose a device for processing eye tissue by means of a pulsed laser beam which does not have at least some of the disadvantages of the prior art. In particular, it is an object of the present invention to propose a device for processing eye tissue by means of a pulsed laser beam focused by a projection optical unit which enables tissue cuts with a vertical cut component, without vertical displacements of the projection optical unit having to be performed for this purpose. 
     According to the present invention, these aims are achieved by means of the features of the independent claims. Further advantageous embodiments are additionally evident from the dependent claims and the description. 
     An ophthalmological device for processing eye tissue by means of a pulsed laser beam comprises a projection optical unit for the focused projection of the laser beam or of the laser pulses into the eye tissue, and a scanner system disposed upstream of the projection optical unit and serving for the beam-deflecting scanning of the eye tissue with the laser beam or the laser pulses in a scanning movement performed over a scanning angle along a scanning line. 
     The abovementioned aims are achieved by the present invention, in particular, by virtue of the fact that at least one optical element is disposed upstream of the projection optical unit, which optical element is designed to generate a divergence of the laser beam, said divergence being dependent on the scanning angle. The divergence of the laser beam, which is varied by the optical element depending on the scanning movement, corresponds to a modulation of the divergence of the laser beam in a direction running perpendicular to the optical transmission axis. The at least one optical element comprises, for example, a wedge plate, a prism, a lens, a diffractive optical element and/or an aspherical mirror. The at least one optical element is arranged in the beam path from the scanner system to the projection optical unit. In one embodiment variant, the at least one optical element is arranged in the scanner system. 
     Preferably, the at least one optical element is designed to generate the divergence—dependent on the scanning angle—of the laser beam for a displacement of the focused projection in the projection direction, said displacement being dependent on the scanning angle. 
     Preferably, the at least one optical element is designed to generate the divergence—dependent on the scanning angle—of the laser beam for a displacement of the focused projection in the projection direction, said displacement being dependent on the scanning angle. 
     Preferably, the at least one optical element is designed to generate the divergence—dependent on the scanning angle—of the laser beam for a targeted tilting of the scanning line. 
     The tilting of the scanning line enables a displacement—dependent on the scanning angle—of the focus of the laser pulses projected into the eye tissue without vertical displacement of the projection optical unit or of individual components of the projection optical unit. 
     The at least one optical element is designed in particular to generate the divergence—dependent on the scanning angle—of the laser beam for a tilting of the scanning line with a defined tilting angle in a plane defined by the scanning line and an optical axis of the projection optical unit. 
     By virtue of a corresponding configuration, in particular dimensional configuration, of the at least one optical element, in one variant a deformation of the scanning line is produced in a plane defined by the scanning line and the optical axis of the projection optical unit. 
     In one embodiment variant, the at least one optical element for setting the divergence—dependent on the scanning angle—of the laser beam can be introduced into the beam path and can be withdrawn from the beam path. 
     In a further embodiment variant, the at least one optical element for setting the divergence—dependent on the scanning angle—of the laser beam is adjustable in the beam path. The at least one optical element is adjustable, for example, by a rotation about an optical axis, a rotation about an axis parallel to the optical axis, a tilting about an axis of rotation and/or a displacement along a translation axis tilted with respect to the optical axis. 
     In one embodiment variant, the ophthalmological device comprises a rotation element arranged in the beam path and serving for rotating a scanning plane defined by the scanning movement about an optical transmission axis, and the at least one optical element is disposed upstream of the rotation element in the beam path. 
     In a further embodiment variant, the ophthalmological device comprises a further, second scanner system disposed downstream of the scanner system and serving for scanning the eye tissue with the laser beam along a processing line, wherein the scanning movement of the upstream first scanner system is superimposed on the processing line, and wherein the at least one optical element is designed to generate the divergence—dependent on the scanning angle—of the laser beam for a targeted tilting of a cutting area defined by the scanning line and the processing line. 
     In one embodiment variant, the ophthalmological device comprises a control module, which is designed to adjust the at least one optical element in such a way that with the divergence—dependent on the scanning angle—of the laser beam the scanning line is tilted with a predefined tilting angle. In the case of the variant with the downstream second scanner system, the control module is designed to adjust the at least one optical element in such a way that with the divergence—dependent on the scanning angle—of the laser beam, the cutting area is tilted with a predefined tilting angle. 
     The control module is designed in particular to adjust the at least one optical element in such a way that with the divergence—dependent on the scanning angle—of the laser beam, the scanning line is tilted with the predefined tilting angle in a plane defined by the scanning line and an optical axis of the projection optical unit. 
     In a further embodiment variant, the control module is designed, during the processing of the eye tissue, to determine a changed tilting angle and to adjust the at least one optical element in such a way that the scanning line or the cutting area is tilted with the changed tilting angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the present invention is described below on the basis of an example. The example of the embodiment is illustrated by the following enclosed figures: 
         FIG. 1 : shows a block diagram schematically illustrating an ophthalmological device for processing eye tissue with a pulsed laser beam, which device comprises a scanner system for scanning the eye tissue along a scanning line and a tilting system for tilting the scanning line. 
         FIG. 1   a : shows a block diagram of the ophthalmological device in which, for the purpose of tilting the scanning line, at least one optical element is disposed upstream of the projection optical unit and generates in the beam path a laser beam divergence dependent on the scanning angle. 
         FIG. 1   b : shows a block diagram of the ophthalmological device in which, for the purpose of tilting the scanning line, a divergence modulator is disposed upstream of the scanner system and dynamically changes the divergence of the laser beam. 
         FIG. 1   c : shows a block diagram of an application head of the ophthalmological device, in which application head the projection optical unit can be tilted about an axis of rotation for the purpose of tilting the scanning line. 
         FIG. 1   d : shows a block diagram illustrating the projection optical unit and correspondingly the scanning line in a tilted state. 
         FIG. 2   a : shows a schematic cross section through a portion of the beam path which illustrates the scanning movement of the laser beam by a scanning angle and the resultant movement of the focus of the laser beam along the scanning line. 
         FIG. 2   b : shows the schematic cross section of the beam path portion in the case of a variation of the divergence of the laser beam depending on the scanning angle, and the resultant tilting of the scanning line by a tilting angle. 
         FIG. 3 : shows a schematic cross section of a portion of the beam path in a divergence modulator with at least one displaceable lens and illustrates the laser beam divergence varied by the displacement of the lens. 
         FIG. 4   a : shows in the plan view of the cornea, the superimposition of the scanning movement onto a processing line for processing the eye tissue in an extended processing region. 
         FIG. 4   b : shows, in the cross section of the cornea, the tilted scanning line along which the eye tissue is scanned and processed by the pulsed laser beam. 
         FIG. 4   c : shows, in the cross section of the cornea, the tilted scanning lines of a plurality of processing paths along which the eye tissue is scanned and processed by the pulsed laser beam. 
         FIG. 5 : shows, in the upper part in the plan view of the cornea, an exemplary application of a circle-arc-shaped conic path cut which, as is illustrated in the cross section of the cornea illustrated in the lower part, is based on a tilted scanning line that is moved along a circle-arc-shaped processing line. 
         FIG. 6 : shows, in the upper part in the plan view of the cornea, an exemplary application of two circle-arc-shaped vertical cuts which, as is illustrated in the cross section of the cornea illustrated in the lower part, are in each case based on a tilted scanning line that is moved along the relevant processing line, in a manner oriented in the direction of a circle-arc-shaped processing line. 
         FIG. 7 : shows, in the upper part in the plan view of the cornea, an exemplary application of a plurality of vertical cuts which are oriented toward a common center and which, as is illustrated in the cross section of the cornea illustrated in the lower part, are in each case based on a tilted scanning line that is moved along the relevant processing line, in a manner oriented in the direction of a processing line oriented toward the center. 
     
    
    
     WAYS OF EMBODYING THE INVENTION 
     In  FIGS. 1 ,  1   a  and  1   b , the reference sign  1  in each case refers to an ophthalmological device for processing eye tissue by means of laser pulses, for example the cornea  22  or other tissue of an eye  2 . 
     As is illustrated schematically in  FIGS. 1 ,  1   a  and  1   b , the ophthalmological device  1  comprises an optical transmission system  100  for transmitting laser pulses of a pulsed laser beam L supplied by a laser source  18  to a projection optical unit  10 . The projection optical unit  10  is designed for the focused projection of the pulsed laser beam L or of the laser pulses for the punctiform tissue decomposition at a focus F (focal point) within the eye tissue. In  FIGS. 1 ,  1   a ,  1   b ,  1   d ,  2   a  and  2   b , the laser beam L projected by the projection optical unit  10  is designated by the reference sign L*. 
     The laser source  18  comprises, in particular, a femtosecond laser for generating femtosecond laser pulses having pulse widths of typically 10 fs to 1000 fs (1 fs=10 −15  s). The laser source  18  is arranged in a separate housing or in a housing jointly with the projection optical unit  10 . 
     It should be emphasized at this juncture that the reference sign L generally designates the pulsed laser beam L or the laser pulses thereof in the beam path from the laser source  18  as far as the focus F, but that depending on the context further reference signs are also used to designate the pulsed laser beam L or the laser pulses thereof at a specific location in the beam path or in the optical transmission system  100 . 
     As is illustrated in  FIG. 1   c , the projection optical unit  10  is incorporated into an application head  3 , for example, which can be placed onto the eye  2 . The application head  3  is preferably placed onto the eye  2  via a contact body  31 , which is light-transmissive at least in places, and fixed to the eye  2  by means of a vacuum-controlled suction ring  32 , for example, wherein the contact body  31  and the suction ring  32  are connected to the application head  3  fixedly or removably. In one embodiment variant, the projection optical unit  10  comprises a focusing device  19  for setting the depth of focus, for example one or a plurality of movable lenses or a drive for moving the entire projection optical unit  10 . 
     As can be seen in  FIGS. 1 ,  1   a  and  1   b , the ophthalmological device  1  comprises at least one scanner system  14  disposed upstream of the projection optical unit  10  and serving for scanning the eye tissue along a scanning line s. The scanner system  14  is designed to deflect the pulsed laser beam L or the laser pulses in order to scan the eye tissue in a processing fashion. The scanner system  14  comprises one or a plurality of movable deflection mirrors, for example a rotating polygon mirror (polygon scanner), and enables beam-deflecting scanning of the eye tissue with the pulsed laser beam L in a scanning movement s′ performed over a scanning angle β along a scanning line s, as is illustrated in  FIG. 2   a . By means of the scanning movement s′, the focus F of the projected laser beam L* is moved along the scanning line s, for example proceeding from the position of the focus F in the case of a deflection of the laser beam L with the scanning angle β 1  to the position of the focus F′ in the case of a deflection of the laser beam L with the scanning angle β 2 . 
     The beam-deflecting scanner system  14  is embodied as a resonant, oscillating, or freely addressable scanner depending on the operating mode and/or construction and comprises, for example, a galvanoscanner, a piezo-driven scanner, an MEM (microelectro-mechanical scanner), an AOM (acousto-optical modulator) scanner or an EOM (electro-optical modulators) scanner. 
     As is illustrated in  FIGS. 1   a  and  1   b , in one embodiment variant the ophthalmological device  1  comprises a rotation element  12 , which is arranged in the beam path and is disposed downstream of the scanner system  14  and serves for rotating a scanning plane defined by the scanning movement s′ and the optical transmission axis about the optical transmission axis, for example a K-mirror. In  FIGS. 1   a  and  1   b , the laser beam L with the scanning plane rotated by the rotation element  12  is designated by the reference sign Lr. 
     In one embodiment variant, the ophthalmological device  1  comprises a further, optional scanner system  11  disposed upstream of the projection optical unit  10  and downstream of the scanner system  14 . The scanner system  11  is designed to scan the eye tissue with the pulsed laser beam L or the laser pulses along a processing line b, as is illustrated by way of example in the plan view in  FIG. 4   a . A meandering processing line b is illustrated in the example in  FIG. 4   a ; the person skilled in the art will understand that the processing line b, depending on the application and driving of the scanner system  11 , can also assume other line shapes, for example spiral, circular, or a freeform shape extending over a part or all of the region B of the eye tissue that is to be processed. The scanner system  11  is embodied as a mechanical scanner that moves the projection optical unit  10  over the entire processing region B along the processing line b by means of one or a plurality of movement drivers, or the scanner system  11  is embodied in a beam-deflecting fashion, for example as a galvanoscanner, and comprises one or two deflection mirrors—movable about respectively one or two axes—for deflecting the pulsed laser beam L or the laser pulses over the entire processing region B along the processing line b. 
     The scanner system  14  disposed upstream of the scanner system  11  has a scanning speed that is a multiple of the scanning speed of the scanner system  11 . Accordingly, the scanner system  14  can also be designated as a fast scan system that generates the deflected laser, beam Lfs, and the scanner system  11  can be designated as a slow scan system that generates the deflected laser beam Lss. The two scanner systems  11 , are designed and coupled such that the scanning movement s′ running along the scanning line s is superimposed on the processing line b, as is illustrated schematically and by way of example in the x/y plan view in  FIG. 4   a . As the scanning line s defines a cutting line in the case of a single scanner system  14  having a single scanning axis, a cutting area is thus defined by the superimposition of the scanning line s onto the processing line b. 
     As is illustrated schematically in  FIG. 1 , the ophthalmological device  1  furthermore comprises a tilting system  4  for tilting the scanning line s or the cutting area. As can be seen in  FIGS. 1   d  and  2   b , the tilted scanning line s* is tilted by the tilting angle γ relative to the scanning line s in a plane running through the optical axis o of the projection optical unit  10  and of the scanning line s. Accordingly, the tilting system  4  also enables a tilting of the cutting area defined by the scanning line s and processing line b by the tilting angle γ, for example—depending on the application and control—a tilting of the entire cutting area or of individual paths defined by the processing line b. 
     In the example in  FIG. 4   a , the scanning movement s′ running along the scanning line s or the tilted scanning line s* is superimposed on the meandering processing line b and thus generates a cutting area extended over the processing region B when moving over the entire processing line b.  FIGS. 4   b  and  4   c  show the cross-sectional illustrations—corresponding to  FIG. 4   a —of the cornea  22  applanated by means of the contact body  31  after moving over a path or four successive paths of the processing line b with a scanning movement s′ along the tilted scanning line s*. The tilted scanning line s* of the exemplary application illustrated in  FIGS. 4   a ,  4   b ,  4   c  enables the correction or removal of residual errors in mutually adjacent processing paths which arise when the optical axis o of the projection optical unit  10  is not oriented perpendicularly to the applanation area of the contact body  31 . 
     The exemplary application in  FIG. 5  shows, in the upper part, a plan view of the cornea  22  and a schematically illustrated conic path cut  23  made therein, the cross section of which is illustrated in the lower part of  FIG. 5 . The conic path cut  23  is produced by the superimposition of a scanning movement s′ performed along a tilted scanning line s* onto a circle-arc-shaped processing line b, wherein the tilted scanning line s* is oriented for example perpendicularly to the processing line b. 
     The exemplary application in  FIG. 6  shows, in the upper part, a plan view of the cornea  22  and two schematically illustrated circle-arc-shaped vertical cuts  24  made therein, a cross section of which is illustrated in the lower part of  FIG. 6 . The two vertical cuts  24  are in each case produced by the superimposition of a scanning movement s′ performed along a tilted scanning line s* onto a circle-arc-shaped processing line b, wherein the tilted scanning line s* is additionally oriented in the direction of the relevant processing line b. 
     The exemplary application in  FIG. 7  shows, in the upper part, a plan view of the cornea  22  and a plurality of schematically illustrated vertical cuts  25  made therein, which are oriented rectilinearly toward a center point Z (vertex) of the cornea  22  and a cross section of which is illustrated in the lower part of  FIG. 6 . The vertical cuts  25  are in each case produced by the superimposition of a scanning movement s′ performed along a tilted scanning line s* onto a rectilinear processing line b oriented toward the center point Z (vertex) of the cornea  22 , wherein the tilted scanning line s* is additionally oriented in each case in the direction of the relevant processing line b. 
     In order to control the tilting of the scanning line s or the cutting area, the tilting system  4  comprises a control module  40 , which is designed to control components of the tilting system  4  in such a way that the scanning line s (and thus, if appropriate, also the cutting area) is tilted by a predefined tilting angle γ in a plane running through the optical axis o of the projection optical unit  10  and the scanning line s. The tilting angle γ is fixedly defined, for example, is input via a user interface or is constantly changed by a control function of the control module  40  during the processing of the eye tissue. The control module  40  comprises a programmable control device, for example one or a plurality of processors with program and data memory and programmed software modules for controlling the processors. 
     Depending on the embodiment variant, the tilting system  4  comprises different components which are provided for tilting the scanning line s and are connected to the control module  40  for control purposes. 
       FIG. 1   a  illustrates an ophthalmological device  1 , in which the tilting system  4  comprises one or a plurality of optical elements  13  which, disposed upstream of the projection optical unit  10 , are arranged in the beam path from the scanner system  14  to the projection optical unit  10  and which are designed to generate in the beam path a divergence δ, δ 1 , δ 2  of the laser beam L, said divergence being dependent on the scanning angle β, β 1 , β 2  (see  FIG. 2   b ). 
     As is illustrated in  FIG. 1   a , the optical element  13  is disposed downstream of the scanner system  14  and varies the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  of the laser beam L deflected by the scanner system  14 . The laser beam L with the divergence δ, δ 1 , δ 2  varied by the optical element  13  depending on the scanning angle β, β 1 , β 2  is designated by the reference sign Ldd in  FIGS. 1   a  and  2   b . In the embodiment variant with the optional rotation element  12 , the optical elements  13  or the optical element  13  are/is disposed upstream of the rotation element  12  in the beam path. 
     As is illustrated in  FIG. 2   a , the laser beam L in the absence of the optical element  13  has in each case an unchanged, constant divergence δ for different scanning angles β, β 1 , β 2 . A divergence δ of approximately zero is often set. With the optical element  13  present, however, the laser beam L has a different divergence δ 1 , δ 2  for different scanning angles β, β 1 , β 2 , as illustrated in  FIG. 2   b . As can be seen in  FIG. 2   b , the optical element  13  is designed such that it varies the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  such that the focus F, F* of the projected laser beam is displaced depending on the scanning angle β, β 1 , β 2  in the projection direction, thus resulting in a tilted scanning line s* which is tilted from the untilted scanning line s by the tilting angle γ in the plane formed by the optical axis o of the projection optical unit  10  and of the scanning line S. When the scanning line s is tilted, the eye tissue is scanned in a beam-deflecting manner along the tilted scanning line s* by the scanner system  14  with the pulsed laser beam L in a scanning movement s′ performed over the scanning angle β, as is illustrated in  FIG. 2   b . In this case, the focus F of the projected laser beam L* is moved by the scanning movement s′ along the tilted scanning line s*, for example proceeding from the position of the focus F in the case of a deflection of the laser beam L with the scanning angle β 1  toward the position of the focus F* in the case of a deflection of the laser beam L with the scanning angle β 2 . 
     Embodiments of the optical elements  13  or of the optical element  13  comprise, for example, wedge plates, prisms, lenses, diffractive optical elements and aspherical mirrors. 
     In an alternative embodiment variant, the optical element  13  is arranged directly in the scanner system  14  and configured, for example, as a deflection mirror having a variable surface curvature. 
     In order to set the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2 , the optical elements  13  or the optical element  13  can be introduced into the beam path or withdrawn from the beam path. As an alternative or in addition, the optical elements  13  or the optical element  13  can be set or adjusted for the purpose of setting the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2 , for example by rotation of the optical elements  13  about the optical axis o, by tilting of the optical elements  13  about an axis of rotation, or by displacement of the optical elements  13  along a translation axis tilted relative to the optical axis o. 
     In the embodiment variant with the optional scanner system  11 , which scans the eye tissue with the laser beam L or the laser pulses along a processing line b on which the scanning movement s′ of the scanner system  14  disposed upstream is superimposed, the optical elements  13  are designed to generate the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  for a targeted tilting of a cutting area defined by the scanning line s and the processing line b. 
     The control module  40  is designed to set the optical elements  13  or the optical element  13  such that the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  brings about a tilting of the scanning line s or of the cutting area defined by the scanning line s and the processing line b by the predefined tilting angle γ. For this purpose, the control module  40  comprises a control function which, for tilting angles γ that are predefined or constantly calculated anew during the processing of the eye tissue, determines respectively assigned control values for setting the optical elements  13 , for example control values for setting an angle of rotation of the optical elements  13  about the optical axis o, a degree of tilting of the optical elements  13  about an axis of rotation or a position of the optical elements  13  on a translation axis tilted relative to the optical axis o, thereby defining the relative position of the optical elements  13  in the beam cross section, or a surface curvature of the optical elements  13 . 
       FIG. 1   b  illustrates an ophthalmological device  1  in which the tilting system  4  comprises a divergence modulator  15 , which is disposed upstream of the scanner system  14  and which is designed to dynamically vary the divergence δ of the laser beam L. 
       FIG. 3  schematically illustrates an embodiment variant of the divergence modulator  15  having two serially arranged optical lenses  151 ,  152 , at least one of which is displaceable for modulating the divergence δ of the laser beam L on an optical transmission axis w. For dynamically modulating the divergence δ of the laser beam L, the movable lens  151  is coupled to a movement driver. As can be seen in the example in  FIG. 3 , in the case of a first basic position  151 ′ of the movable lens, the laser beam L has a corresponding divergenceδ 1 . In the case of a displacement of the movable lens  151  on the transmission axis w, the divergence of the laser beam L varies continuously and has a changed divergence δ 2  in the case of the position  151 ″ displaced by the excursion distance Δ. The laser beam L with the divergence δ, δ 1 , δ 2  modulated by the divergence modulator  15  is designated by the reference sign Ld in  FIGS. 1   b ,  2   b  and  3 . 
     In alternative embodiments, the divergence modulator  15  comprises a spatial light modulator for modulating the wavefront of the laser beam L, a surface light modulator for modulating the reflection angles at a plurality of points of a reflection surface over which the laser beam L is guided, a refraction modulator for modulating the refractive index of an optical element at a plurality of points in the cross section of the beam path, and/or an amplitude modulator for amplitude modulation at a plurality of points in the cross section of the beam path, that is to say in the beam profile, of the laser beam L. 
     The divergence modulator  15  is designed to modulate the divergence δ, δ 1 , δ 2  of the laser beam L (during the scanning movement s′) with a frequency or speed of at least the same magnitude as that with which the scanner system  14  performs the scanning movement s′ over the scanning angle β. Moreover, the divergence modulator  15  is coupled to the scanner system  14  such that the variation of the divergence δ, δ 1 , δ 2  of the laser beam L is synchronized with the scanning angle β, β 1 , β 2  of the scanning movement s′. As is illustrated schematically in  FIG. 2   b , this results in a divergence δ, δ 1 , δ 2  of the laser beam L which varies with the scanning angle β, β 1 , β 2 , i.e. is dependent on the scanning angle β, β 1 , β 2 . 
     The divergence modulator  15  can be set and controlled by the control module  40  with regard to modulation frequency or modulation speed and modulation depth or modulation intensity, e.g. the excursion distance Δ in the embodiment according to  FIG. 3 . The modulation frequency of the divergence modulator  15  is synchronized for example with the scanning speed of the scanner system  14 , e.g. a displacement over the excursion distance Δ is carried out during a scanning movement s′ over the scanning angle β (e.g. from β 1  to β 2 ). 
     As has already been described above in connection with the optical element  13 , in the case of a divergence δ, δ 1 , δ 2  of the laser beam L that is varied depending on the scanning angle β, β 1 , β 2 , a displacement of the focus F, F* of the projected laser beam L*, said displacement being dependent on the scanning angle β, β 1 , β 2 , arises, as is illustrated by way of example in  FIG. 2   b . In the case of corresponding synchronization of the variation of the divergence δ, δ 1 , δ 2  of the laser beam L with the scanning angle β, β 1 , β 2  of the scanning movement s′, a tilting of the scanning line s results. The tilting angle γ between the tilted scanning line s* and the untilted scanning line s in the plane formed by the optical axis o of the projection optical unit  10  and of the scanning line s can be adjusted by the modulation depth or modulation intensity, e.g. by the excursion distance Δ. 
     If the divergence modulator  15  is designed to modulate the divergence δ, δ 1 , δ 2  of the laser beam L with a greater frequency or speed than the scanner system  14  performs the scanning movement s′, this does not make it possible to tilt the scanning line s merely by the tilting angle γ, but rather to deform the scanning line s in the plane formed by the optical axis o of the projection optical unit  10  and of the untilted scanning line s, wherein, in the case of a varying modulation speed, a “nonlinear tilting” and thus a deformation of the scanning line s in the projection direction are also made possible. 
     In the embodiment variant with the optional scanner system  11 , which scans the eye tissue with the laser beam L or the laser pulses along a processing line b on which the scanning movement s′ of the upstream scanner system  14  is superimposed, the divergence modulator  15  enables a divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  for a targeted tilting of the cutting area defined by the scanning line s and the processing line b. At a modulation speed of the divergence modulator  15  which is higher than the scanning speed of the scanning system  14 , the divergence modulator  15  enables a targeted deformation of said cutting area. 
     The control module  40  is designed to set the divergence modulator  15  such that the divergence δ, δ 1 , δ 2  of the laser beam L depending on the scanning angle β, β 1 , β 2  brings about a tilting of the scanning line s or of the cutting area defined by the scanning line s and the processing line b by the predefined tilting angle γ. For this purpose, the control module  40  comprises a control function which, for tilting angles γ that are predefined or constantly calculated anew during the processing of the eye tissue, determines respectively assigned control values for setting the divergence modulator  15 , in particular for setting the modulation depth or modulation intensity, e.g. the excursion distance Δ, and the modulation speed, wherein the synchronization between the scanner system  14  and the divergence modulator  15  is preferably effected via common synchronization lines or synchronization signals. For a targeted deformation of the cutting area defined by the scanning line s and the processing line b at a correspondingly high modulation speed of the divergence modulator  15 , the control module  40  controls the divergence modulator  15  with dynamically changing control values for a modulation depth or modulation intensity, e.g. the excursion distance Δ, and/or modulation speed varying during the scanning movement s′. 
     In an embodiment variant in accordance with  FIG. 1   b , the ophthalmological device  1  merely comprises one scanner system  14  or  11 , for example a galvanoscanner system, which is disposed between the divergence modulator  15  and the projection optical unit  10  and which is designed to scan the eye tissue two-dimensionally, that is to say both in a first scanning direction x and in a second scanning direction y perpendicular thereto (see  FIG. 4   a ), in a processing fashion along a scanning line s or processing line b. The control module  40  is designed to control the scanner system  14  or  11  for the processing of the eye tissue along different scanning lines s or processing lines b which have, for example, a meandering, spiral, circular or freeform shape and extend over a part or all of the region B of the eye tissue that is to be processed. The control module  40  is additionally designed to control processing depth in the z-direction, which is perpendicular to the first scanning direction x and second scanning direction y, by corresponding setting of the divergence modulator  15 . The processing depth in the z-direction can thus be modulated by corresponding driving of the divergence modulator  15  by the control module  40  during the processing of the eye tissue in the scanning directions x, y along the scanning line s or processing line b. As a result, not only planar but also curved cutting areas are possible in the eye tissue, in particular cutting areas shaped in a targeted manner, for example parts of sphere surfaces, ellipsoid surfaces, one-dimensionally or two-dimensionally undulatory shapes or other freeform areas, without the projection optical unit  10  or optical components thereof having to be moved for this purpose. In this case, both the depth adjustment range in the eye tissue that is made possible by the variable setting of the modulation depth or modulation intensity of the divergence modulator  15  in the z-direction, and the excursion range of the requisite excursion distance Δ of the lens  151  are significantly smaller than the thickness of the cornea  22 , of the lens or of other tissue parts of the eye. Consequently, in the eye tissue a modulation of the processing depth in the z-direction is possible with a significantly higher frequency than would be possible by moving the large mass of the projection optical unit  10  or optical components thereof. 
       FIG. 1   c  illustrates an ophthalmological device  1  in which the tilting system  4  is based on the projection optical unit  10 , which is configured such that it can be tilted about an axis of rotation q (or q′) running perpendicularly to its optical axis o and to the scanning line s. As is indicated with the axis of rotation q′, the axis of rotation q′ need not run directly through the optical axis o and the scanning line s; it suffices if the axis of rotation q, q′ runs perpendicularly to a plane defined by the scanning line s and the optical axis o. 
     As is illustrated in  FIG. 1   d , a tilting of the projection optical unit  10  about the axis of rotation q, q′ with the rotation angle γ* brings about a tilting of the scanning line s by the tilting angle γ=γ*. In the example in  FIG. 1   d , the tilted scanning line s* in the plane defined by the scanning line s and the optical axis of the projection optical unit is tilted relative to the untilted scanning line s by the same tilting angle γ as the optical axis o of the projection optical unit  10  relative to a normal n to the surface with respect to the contact body  31 . However, the tilting angle γ and the rotation angle γ* can also be different, if e.g. the object- and image-side refractive indices of the projection optical unit  10  are different. 
     In the embodiment variant with the optional scanner system  11 , which scans the eye tissue with the laser beam L or the laser pulses along a processing line b on which the scanning movement s′ of the upstream scanner system  14  is superimposed, the projection optical unit  10  that can be tilted about the axis of rotation q, q′ enables a corresponding tilting of the cutting area defined by the scanning line s and the processing line b. 
     For setting and fixing the tilting of the projection optical unit  10  and the resulting tilting of the scanning line s or cutting area, the ophthalmological device  1  in one embodiment variant comprises an adjusting device  16  coupled to the projection optical unit  10 . 
     For the automated tilting of the projection optical unit  10 , the ophthalmological device  1  in a further embodiment variant comprises a drive  17  coupled to the projection optical unit  10 . Moreover, the control module  40  is connected to the drive  17  for the purpose of controlling the tilting of the projection optical unit  10  and the resultant tilting of the scanning line s or of the cutting area in accordance with a tilting angle γ that is predefined or is constantly calculated anew during the processing of the eye tissue.