DE102018216507A1 - Apparatus and method for material processing by means of laser radiation - Google Patents

Abstract

The invention relates to an apparatus and a method for material processing by means of laser radiation with a laser radiation source which emits pulsed laser radiation for interaction with the material, a pulsed processing laser radiation in the material focusing on an interaction center optics, one of the position of the interaction center in the material an adjusting scanning device, wherein each machining laser pulse interacts with the material in a zone surrounding the associated interaction center, so that in the interaction zones material is separated, and a control device which controls the scanning device and the laser beam source so that in the material by juxtaposing interaction zones In this case, the control device, the laser beam source and the scanning device is driven so that the distances of the interaction centers and time sequence of the laser pulses, the sound propagation take into account the material or that the distances of the interaction centers and / or the time sequence of the laser pulses are adjusted so that they develop a sound effect mediated joint effect in the material.

Description

The invention relates to an apparatus for material processing by means of laser radiation with a laser radiation source which emits pulsed laser radiation for interaction with the material, an optics focusing the pulsed processing laser radiation into the material on an interaction center, a scan device adjusting the position of the interaction center in the material. where each machining laser pulse is in a his
associated interaction center surrounding the material interacts with the material, so that in the interaction zones material is separated, and a control device which controls the scanning device and the laser beam source so that in the material by juxtaposition of interaction zones creates a cut surface.

The invention further relates to a method for processing materials by means of laser radiation, wherein the pulsed processing laser radiation is generated, is focused on interaction in the material on interaction centers, and the position of the interaction centers is adjusted in the material, each machining laser pulse in a zone around the Interaction center associated with it interacts with the material and material is separated and a cut surface in the material is created by juxtaposing interaction zones.

The invention further relates to an apparatus for material processing by means of laser radiation, with a laser radiation source which emits pulsed laser radiation for interaction with the material, a pulsed processing laser radiation along an optical axis in the material focusing on an interaction center optics, one of the position of the Interaction center in the material-adjusting scanning device, wherein each machining laser pulse in a surrounding the associated interaction center zone interacts with the material so that material is separated, and a control device which controls the scanning device and the laser beam source so that in the material by juxtaposing interaction zones a cut surface is created.

The invention also relates to a method of material processing by means of laser radiation, is generated in the pulsed laser radiation and focused on interaction in the material along an optical axis to interaction centers, and the position of the interaction centers in the material is adjusted, each machining laser pulse in a zone interacting with the material around the interaction center assigned to it and material is separated and a cut surface in the material is produced by juxtaposing interaction zones.

These devices and corresponding methods for material processing are particularly suitable for forming cut surfaces within a transparent material. Cut surfaces within a transparent material are produced, for example, in laser surgical procedures and there especially in ophthalmological surgery. Treatment laser radiation into the tissue, i. focused below the tissue surface on an interaction center. In an interaction zone lying around it material layers are separated. The zone usually corresponds to the focus spot. Typically, the laser pulse energy is chosen so that in the interaction zone, an optical breakthrough occurs in the tissue.

In the tissue run after an optical breakthrough from time to time several processes, which are initiated by the laser radiation pulse. The optical breakthrough first creates a plasma bubble in the material. This plasma bubble grows after being formed by expanding gas. Subsequently, the gas generated in the plasma bubble is taken up by the surrounding material and the bubble disappears again. However, this process takes much longer than the formation of the bubble itself. If a plasma is generated at a material interface, which can also be within a material structure, a material removal takes place from the interface. One speaks then of photoablation. A plasma bubble that separates previously bonded layers of material usually refers to photodisruption. For the sake of simplicity, all such processes will be summarized herein by the term interaction, i. This term includes not only the optical breakthrough but also the other material-separating effects.

For a high accuracy of a laser surgical procedure, it is essential to ensure a high localization of the effect of the laser beams and to avoid collateral damage in adjacent tissue as far as possible. It is therefore customary in the prior art to use pulsed laser radiation, so that the threshold for the energy density necessary for triggering an optical breakthrough is exceeded only in the individual pulses. The US 5,984,916 shows in this regard clearly that the spatial extent of the interaction zone only depends significantly on the pulse duration, as long as a pulse length of 2 ps is exceeded. At values of a few 100 fs, the interaction zone size is almost pulse duration independent. A high focusing of the laser beam in combination with very short pulses, ie under 1 ps, allows the interaction zone to be used precisely in one material.

The use of such pulsed laser radiation has recently gained particular acceptance for the laser-surgical correction of defective vision in ophthalmology. Defective vision of the eye often results from the fact that the refractive properties of the cornea and lens do not produce optimal focusing on the retina. This type of pulsation is also the subject of the invention described here.

The mentioned US 5984916 describes a method for producing cuts by means of suitable generation of optical breakthroughs, so that in the end the refractive properties of the cornea are specifically influenced. A multiplicity of optical breakthroughs are placed against one another in such a way that the cut surface within the cornea of the eye isolates a lenticular subvolume. The lenticular subvolume separated from the remaining corneal tissue is then removed from the cornea via a laterally opening cut. The shape of the partial volume is chosen so that after removal, the shape and thus the refractive properties of the cornea are changed so that the desired refractive error correction is effected. The required cut surface is curved and circumscribes the partial volume, which requires a three-dimensional adjustment of the focus. Therefore, a two-dimensional deflection of the laser radiation with simultaneous focus adjustment in a third spatial direction is combined. This is subsumed under the term "scan", "misrepresent" or "distract".

When constructing the cut surface by juxtaposing optical breakthroughs in the material, the generation of an optical breakthrough is many times faster than it takes until a plasma generated therefrom or a gas bubble generated by it is absorbed again in the tissue. From the publication A. Heisterkamp et al., The Ophthalmologist, 2001, 98: 623-628 , it is known that after generating an optical breakthrough in the cornea at the focal point at which the optical breakthrough was generated, a plasma bubble is formed, which can grow together with neighboring bubbles into macrobubbles. The publication states that the combination of still growing plasma bubbles reduces the quality of cut.

In order to achieve a good cut quality, the prior art uses certain sequences in which the optical breakthroughs are generated. Thus, an association of growing plasma bubbles should be prevented. Since, of course, a cut is sought in which as few bridges connect the material or tissue, ultimately the generated plasma bubbles must in any case grow together to form a cut surface. Otherwise, material connections remained and the cut would be incomplete. The DE 102005039833A1 proposes to lower the laser pulse energy below the breakthrough threshold and several laser pulses overlapping and temporally deliver directly into the tissue.

From the DE 102005049218A1 The Applicant is known to apply the laser pulses with an energy below the breakthrough threshold and at a distance below 10 .mu.m to each other. In order to keep the processing time for a surface as low as possible, laser pulse rates from 100 kHz up to a few MHz are used, the laser pulse rates being selected essentially depending on the properties of the laser used and the positioning speed of the scanners.

It is also known that the plasma formation occurs suddenly in an interaction above the breakdown threshold of the material and acts as a small explosion, and is therefore associated with an acoustic effect ("bang"). Depending on the intensity of the sound, sound waves also occur in the event of a sudden warming of material, without the necessity of permanent material processing or gas bubble formation. Photoacoustic methods are therefore also used for dosimetry, for example in under- and suprathreshold laser treatment of the retina (eg DE 10 2009 016 184 )). A laser-induced blistering is always connected to the formation of a mechanical wave or sound wave into the surrounding tissue.

In the US 6679855 It has been proposed to process eye tissue with focused high-intensity ultrasound energy. For this purpose, an ultrasonic transducer must be placed on the cornea.

The invention is therefore based on the object to produce material modifications, especially cuts of good quality in the material with a greater distance of the interaction zones.

The invention is defined in the independent claims.

This object is achieved with a device of the aforementioned type according to the invention, wherein the control device controls the laser beam source and the scanning device so that the distances of the interaction centers and time sequence of the laser pulses consider the propagation of sound in the material or that the distances of the interaction centers and / or the temporal Sequence of laser pulses adjusted be that they develop a sound effect mediated joint effect in the material.

The object is further achieved by a method of the aforementioned generic type, in which the distances of the interaction centers and temporal sequence of the laser pulses, the sound propagation are taken into account in the material or the distances of the interaction centers and / or the time sequence in the control of the laser beam source and the scanning device The laser pulses are adjusted so that they develop via sound waves mediated joint effect in the material.

The invention is based on the recognition that the sound waves emanating from different interaction zones in the material can be superimposed and thus a material-separating effect can be achieved.
The inventor now achieves an adjustable material-separating effect by suitably selecting the distance or position of the interaction zones relative to each other and temporal spacing of the laser pulses. The variants according to the invention all use this knowledge.

In a first variant of the invention, two or more laser pulses are temporally and spatially separated so applied that the forming (sound) pressure waves are superimposed so that a targeted influencing of the material separation takes place. In this case, a gain of the generated sound waves can be exploited by a second laser pulse is applied so that the sound wave of the first laser pulse preferably just passes through the interaction zone of the second. The spatial distance of the interaction zones essentially corresponds to the distance traveled by the sound wave generated by the first laser pulse in the time up to the second laser pulse. The relevant material property is thus the speed of sound in the material.

Further laser pulses can then be applied in a corresponding spatial and temporal distance in order to effect a planar material separation.

In a second variant of the invention, two or more laser pulses are applied simultaneously but spatially separated so that the (sound) pressure waves forming are superimposed in such a way that a targeted influencing of the material separation takes place. Here, too, the speed of sound in the material has to be considered.

In this case, the speed of sound in the material can be known a priori or be determined in advance by means of suitable measurement.

The type of material separation according to the invention is particularly suitable for materials which have a preferred direction for splitting (so-called "cleaving"), as is known in a large number of crystalline materials, but also in lamellar tissue layers such as the cornea. Cleaving can also be observed and used in isotropic media such as glass, for example by scoring and subsequent crack propagation due to mechanical stress ("fiber cleaver").

Despite the greater distance between the interaction zones, the cut production according to the invention produces a very fine cut, since the superposition of the acoustic waves and thus their cutting action can be positioned very accurately.

Furthermore, according to the invention, it is possible to consciously refrain from a complete separation of two material regions by leaving more or less uniformly distributed material bridges in the material processing in the cut surface. These material bridges ensure that the material on the cut surface is only perforated and still hangs together via the material bridges. The perforation pattern defines the cut surface. Size and number of material bridges can be selected depending on the application. The introduction of the sequences of the laser pulses is controlled so that the cuts do not completely connect around the interaction zones.

It may also be advantageous to combine the generation of targeted sound waves according to the invention with a conventional device for producing focused sound waves (HIFU = high-intensity focussed ultrasound), as they are, for example, in the WO 2017/062673 is described for use on the eye. On the one hand, it would be possible to increase the effect by superimposing the sound waves on the other, but also to reduce the damage caused by undesirable sound effects by means of targeted "counter-noise" (destructive interference).

The invention is not bound to the production of cuts in the material, and other modifications of the material through the targeted use of sound waves generated by a laser processing are within the scope of the present invention. Likewise, the sound waves may also be generated by laser pulses below the breakthrough threshold of the material.

• 1 ein laserchirurgisches Instrument zur Augenbehandlung,
• 2 eine Schemazeichnung der Wirkung der Laserstrahlung auf die Augenhornhaut beim Instrument der 1,
• 3 eine Schemadarstellung zur Veranschaulichung der Erzeugung und Isolierung eines Teilvolumens mit dem Instrument der 1,
• 4 eine schematische Schnittdarstellung durch die Augenhornhaut zur Veranschaulichung der Entnahme des Hornhaut-Volumens im Zusammenhang mit der augenchirurgischen Refraktionskorrektur,
• 5 eine Schemadarstellung hinsichtlich des Aufbaus des Behandlungsgerätes der 1
• 6 eine Schemadarstellung einer ersten Variante der Erfindung
• 7 eine Schemadarstellung einer Abwandlung der ersten Variante der Erfindung
• 8 eine Schemadarstellung einer zweiten Variante der Erfindung

The invention will be explained in more detail with reference to the drawings by way of example. In the drawings shows:

• 1 a laser surgical instrument for eye treatment,
• 2 a schematic drawing of the effect of laser radiation on the cornea in the instrument of 1 .
• 3 a schematic representation to illustrate the generation and isolation of a partial volume with the instrument of 1 .
• 4 a schematic sectional view through the cornea to illustrate the removal of the corneal volume in connection with the ophthalmic refractive correction,
• 5 a schematic representation of the structure of the treatment device of 1
• 6 a schematic representation of a first variant of the invention
• 7 a schematic representation of a modification of the first variant of the invention
• 8th a schematic representation of a second variant of the invention

A treatment device for eye surgery is in 1 represented and with the general reference numeral 1 Mistake. The treatment device 1 is for the introduction of laser cuts in one eye 2 a patient 3 educated. For this purpose, the treatment device 1 a laser device 4 on, coming from a laser source 5 a laser beam 6 which gives off as a focused beam 7 in the eye 2 or the cornea is directed. Preferably, the laser beam 6 a pulsed laser beam with a wavelength between 300 nanometers and 10 micrometers. For processing in iris, lens, trabecular, vitreous, retina or choroid, wavelengths are preferred which have sufficient transmission in aqueous media, eg 450 to 1350 nm. Next is the pulse length of the laser beam 6 in the range between 1 femtosecond and 100 nanoseconds, with pulse repetition rates of 50 to 50,000 kilohertz and pulse energies between 0.001 microjoule and 0.1 millijoule are possible. The treatment device 1 thus produces in the cornea of the eye 2 by deflecting the pulsed laser radiation, a cut surface. In the laser device 4 or their laser source 5 is therefore still a scanner 8th and a radiation intensity modulator 9 is provided.

The patient 3 is on a couch 10 , which is optionally adjustable in three directions to the eye 2 suitable for the incidence of the laser beam 6 align. In preferred construction is the couch 10 motor adjustable. Alternatively, patient bed is less mobile and therefore the treatment device according to the motor adjustable.
The control can in particular by a control unit 11 take place, in principle, the operation of the treatment device 1 controls and to do so via appropriate data connections, such as interconnections 12 connected to the treatment device. Of course, this communication can also be done by other means, such as fiber optics or by radio. The control unit 11 takes the appropriate settings, timing on the treatment device 1 , in particular the laser device 4 before and thus accomplished corresponding functions of the treatment device 1 ,

The treatment device 1 optionally further has a fixing device 15 on which the cornea of the eye 2 opposite the laser device 4 fixed in position. This fixing device 15 can be a known contact glass 45 to which the cornea is applied by negative pressure and which gives the cornea a desired geometric shape. Such contact lenses are known to those skilled in the art, for example from the DE 102005040338 A1 , The disclosure of this document is, as far as the description of a design of the for the treatment device 1 possible contact glass 45 affected is fully included here.
Other modified or improved contact glass forms could also have advantages for the invention and should therefore be included.

The control unit 11 the treatment device 1 still has a planning device 16 on, which will be explained later in more detail.

2 shows schematically the operation of the incident laser beam 6 , The laser beam 6 is focused and falls as the focused laser beam 7 in the cornea 17 of the eye 2 , For focusing is a schematically drawn optics 18 intended. It causes in the cornea 17 a focus in which the laser energy density is so high that in combination with the pulse length of the pulsed laser radiation 6 a non-linear effect in the cornea 17 occurs. For example, each pulse of the pulsed laser radiation 6 in focus 19 an optical breakthrough in the cornea 17 generate, which in turn a in 2 only schematically indicated plasma bubble initiated. When the plasma bubble is formed, the tissue layer separation comprises a larger area than the focus 19 although the conditions for generating the optical breakthrough are only in focus 19 be achieved. In order for an optical breakthrough to be generated by each laser pulse, the energy density, ie the fluence of the laser radiation, must be above a certain, pulse length-dependent threshold value. This connection is the expert from the example of DE 69500997 T2 known. The Cooperation of several laser pulses according to the invention will be described later on the basis of 6-8 explained in more detail.

To perform an ophthalmic refraction correction, by means of the laser radiation 6 from an area within the cornea 17 A corneal volume is removed by separating tissue layers which isolate the corneal volume and then allow it to be removed. To isolate the cornea volume to be removed, the position of the focus is, for example, in the case of pulsed laser radiation 19 the focused laser radiation 7 in the cornea 17 adjusted. This is schematically in 3 shown. The refractive properties of the cornea 17 are deliberately changed by the removal of the volume, so as to achieve the refraction correction. The volume is therefore usually lenticular and is referred to as a lenticle.

In 3 are the elements of the treatment device 1 entered only insofar as they are necessary for the understanding of the cutting surface production. The laser beam 6 becomes, as already mentioned, in a focus 19 in the cornea 17 bundled, and the location of the focus 19 in the cornea is adjusted, so that the focal surface generation at different points focusing energy from laser radiation pulses into the tissue of the cornea 17 is registered. The laser radiation 6 is from the laser source 5 preferably provided as pulsed radiation. The scanner 8th is in the construction of the 3 constructed in two parts and consists of an xy scanner 8a, which is realized in a variant by two substantially orthogonally deflecting galvanometer. The scanner 8a directs the laser source 5 coming laser beam 6 two-dimensional, so after the scanner 9 a deflected laser beam 20 is present. The scanner 8a thus causes an adjustment of the position of the focus 19 substantially perpendicular to the main direction of incidence of the laser beam 6 in the cornea 17 , To adjust the depth position is next to the xy scanner 8a in the scanner 8th another z scanner 8b provided, which is designed for example as an adjustable telescope. The z scanner 8b ensures that the z position is the location of the focus 19 ie, whose position on the optical axis of incidence is changed. The z scanner 8b can the xy scanner 8a be downstream or upstream.
Between laser source 5 and focus 19 Further optical elements influencing the laser beam may be included, such as enlarging or reducing telescopes, scanning and focusing lenses.

For the operating principle of the treatment device 1 The assignment of the individual coordinates to the spatial directions is not essential, just as little as the scanner 8a deflects to each other at right angles axes. Rather, any scanner that is able to focus can be used 19 to adjust in a plane in which the axis of incidence of the optical radiation is not. Further, any non-Cartesian coordinate system can be used to distract or control the position of the focus 19 be used. Examples of this are spherical coordinates or cylindrical coordinates.

The control of the location of the focus 19 done by means of the scanner 8a . 8b under the control of the control unit 11 , the appropriate settings on the laser source 5 which (in 3 not shown) modulator 9 as well as the scanner 8th performs. The control unit 11 ensures proper operation of the laser source 5 as well as the three-dimensional focus adjustment described here by way of example, so that ultimately a cut surface is formed which isolates a specific corneal volume which is to be removed for refractive correction.

The control device 11 operates according to predetermined control data, which, for example, in the here only exemplarily described laser device 4 are specified as target points for the focus adjustment. The control data are usually combined in a control data record. This results in geometric specifications for the cut surface to be formed, for example the coordinates of the target points as a pattern. In this embodiment, the control data set also contains specific values for the focus position adjustment mechanism, eg for the scanner 8th ,
In calculating the control data, the speed of sound in the cornea, which is approximately 1480 m / s, is taken into account in accordance with the invention.
When using alternative materials, such as silicone oil or saline fillings after vitrectomy, appropriately adjusted values should be used. In the case of solids, the deviant propagation behavior of transversal sound waves has to be considered in addition to longitudinal sound waves. For example, the plastic used in intraocular lenses PMMA has a speed of sound for longitudinal waves of about 2550 m / s and for transverse waves of about 1450 m / s. Soft plastics often show significantly lower values.

The production of the cut surface with the treatment device 1 is exemplary in 4 shown. A cornea volume 21 in the cornea 17 is by adjusting the focus 19 in which the focused beam 7 is bundled, isolated. For this purpose, cut surfaces are formed, here exemplified as an anterior flap surface 22 as well as a posterior lenticule cut surface 23 are formed. These terms are to be understood as exemplary only and are intended to refer to the conventional Lasik or Flex process for which the treatment device 1 , as already described, is also formed. The only important thing here is that the cut surfaces 22 and 23 as well as the circumferential edge cut 25 which the cut surfaces 22 and 23 merge at the edges, the corneal volume 21 isolate. Through a opening cut 24 can further increase the corneal volume 21 Anterior limiting corneal flap can be folded down, leaving the corneal volume 21 is removable.

Alternatively, the SMILE procedure can be used where the corneal volume 21 is taken through a small opening cut, like that in the DE 10 2007 019813 A1 is described. The disclosure of this document is incorporated herein in its entirety

5 shows schematically the treatment device 1 , and by her means the importance of the planning device 16 be explained in more detail. The treatment device 1 has at least two devices or modules in this variant. The already described laser device 4 gives the laser beam 6 on the eye 2 from. The operation of the laser device 4 takes place, as already described, fully automatically by the controller 11 ie the laser device 4 The generation and deflection of the laser beam starts in response to a corresponding start signal 6 and thereby generates cut surfaces, which are constructed in the manner described,. The control signals required for operation are received by the laser device 5 from the control unit 11 which previously provided appropriate control data. This is done by means of the planning device 16 , in the 5 merely as an example as part of the control unit 11 is shown. Of course, the planning facility 16 also be designed independently and wired or wirelessly with the controller 11 communicate. It is only essential then that a corresponding data transmission channel between the planning device 16 and the controller 11 is provided.

The planning device 16 generates a control record to the controller 11 is provided for performing the ophthalmic refractive correction. The planning device uses measured data about the cornea of the eye. These data come in the embodiment described here from a measuring device 28 that the eye 2 of the patient 2 measured before. Of course, the measuring device 28 be formed in any way and the appropriate data to the interface 29 the planning device 16 to transfer.

The scheduler now assists the operator of the treatment device 1 in determining the cut surface for the isolation of the corneal volume 21 , This can go to a fully automatic definition of the cut surfaces, which can be effected, for example, that the planning device 16 From the measured data, the cornea volume to be taken 21 determined, defines the boundary surfaces as cutting surfaces and corresponding control data for the control unit 11 generated. At the other end of the automation level, the planning device 16 Provide input possibilities in which a user inputs the cut surfaces in the form of geometric parameters, etc. Intermediate stages provide suggestions for the cut surfaces which the planning device 16 automatically generated and then modified by an editor. In principle, all those concepts which have already been explained in the more general part of the description can be found here in the planning device 16 come into use.

The interaction of several laser pulses according to the invention will now be described with reference to FIG 6-8 explained in more detail.

In this case correspond 6 and 7 the above first variant of the invention, 8th the second variant.

In the following, the energy of each laser pulse is chosen so that an optical breakthrough takes place in the focus.

6 (a) schematically shows a sequence of laser steel foci 19 . 19 ' . 19 " whose spatiotemporal sequence (local distance, time difference .DELTA.t) is selected such that .DELTA.x / .DELTA.t ≥ V _{sound is} selected, where V _{sound is} the speed of sound in the material 17 is. Due to the superimposition of the sound waves produced during plasma generation in the focus of the laser, a directional shock wave is created similar to a Mach cone 30 which can effect a surface material separation.

6 (b) schematically shows a pulse shaping unit 31 with their help a laser pulse of the laser beam 6 is split into two laser pulses spatially displaced by Δx and temporally by Δt. The temporal splitting can be effected by known optical delay paths or in another suitable manner. The spatial displacement can be done for example by separate scanning systems or in another suitable manner.

In 7 a modification of the first variant of the invention is shown. Here follows a first laser pulse 19 , which has, for example, a ring shape with the diameter D, in a precise time difference .DELTA.t a second laser pulse 19 ' pointing to the center of the ring of laser pulse 19 is directed. So that the cutting effect of the sound waves triggered by the laser pulses is superimposed and thus reinforced, the following condition must be observed: Δt = D / (2 * V _sound ) with V _{sound of} the speed of sound in the material 17 , At D = 10μm and V _Schall = 1480 m / s Δt = 3.38 ns. The shaping of the first laser pulse 19 can be done by means of a phase object or in another suitable manner. The time delay between 19 and 19 'can be realized by free-jet or fiber optic delay links.

8th shows an embodiment of the second variant of the invention. This is a pattern of laser pulses 19 . 19 ' . 19 '' applied at the same time, so that between them an increased tissue modification (tissue separation) is induced by shock waves. Again, the patterning of laser pulses may be formed by a phase object or other suitable manner. By a suitable choice of the action zones of the laser pulses, a predetermined superimposition of the sound waves can be achieved here and a targeted modification (eg separation) of the material can be realized.
Phase objects such as phase gratings can be used as phase objects US 6376799 B1 described or programmable spatial light modulators (SLM) are used (see, eg Alex Bardales, Qinggele Li, Bingzhao Zhu, Xiaodong Tao, Marc Reinig, and Joel Kubby, "Generation of Multispot PSF for Scanning Structured Illumination via Phase Retrieval," Mathematical Problems in Engineering, vol. 2016 , doi: 10.1155 / 2016/8207685) whose phase patterns can also be calculated very quickly, ie promptly during a material processing operation, for example by means of Gerchberg-Saxton algorithms ( RW Gerchberg, WO Saxton, "A Practical Algorithm for the Determination of the Phase of Image and Diffraction Planes Pictures," Optik 35, 237 (1972) ). Phase objects can be designed for far and near field configurations (see eg Wu, Liang & Cheng, Shubo & Tao, Shaohua. (2015) , Simultaneous shaping of the amplitude and phase of light in the entire output plane with a phase-only hologram. Scientific Reports. doi: 10.1038 / srep15426).

Also in the context of the present invention are extensions such as depth-dependent or tissue-dependent control of the pressure waves or a spatial positioning of the laser pulses in the axial direction along the direction of laser beam propagation. Furthermore, combinations of different laser pulse durations, wavelengths and polarizations and different laser-matter interactions (ablation, single and multi-photon absorption) can also be exploited.
A monitoring of the cutting effect is possible, for example, with an optical coherence tomograph (OCT). This can also be used to set up a feedback system.

The invention has been explained in a preferred example of the refractive corneal correction, but it is also applicable for the cutting in other suitable materials of any kind, in particular for cutting in the human eye lens for the treatment of cataract.

In addition, material processing in the sense of the invention may include not only cuts, but also, for example, tissue densification, refractive index change, dumping of therapeutically effective cytokines (selective laser trabeculoplasty) or heat-shock proteins (HPS), e.g. for the treatment of diabetic retinopathy. Also in these types of material processing, the directional propagation according to the invention of the sound waves resulting from laser material processing is advantageous, e.g. for inducing or also for avoiding further tissue-altering effects by these sound waves (for example also protection of the capsular bag or the fovea in the case of an incision in the eye lens by taking into account the effects of the sound waves produced during cutting).

Furthermore, depending on the temporal and spatial distance of the laser pulses in a test zone of the tissue to be processed (eg the edge), the intensity threshold can be determined and optimized, starting from which the cutting effect in the tissue begins (eg via imaging such as OCT) or the cutting action itself amplify or dampen by the sound wave superposition. In addition, by means of acoustic sensors directly realized by laser pulse sequence sound characteristic can be determined, optimized or evaluated with regard to relevant parameters, such as speed of sound, which are then included to control the laser pulses.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5984916 [0007, 0009]
• DE 102005039833 A1 [0011]
• DE 102005049218 A1 [0012]
• DE 102009016184 [0013]
• US 6679855 [0014]
• WO 2017/062673 [0027]
• DE 102005040338 A1 [0032]
• DE 69500997 T2 [0034]
• DE 102007019813 A1 [0041]
• US 6376799 B1 [0051]

Cited non-patent literature

• A. Heisterkamp et al., The Ophthalmologist, 2001, 98: 623-628 [0010]
• Alex Bardales, Qinggele Li, Bingzhao Zhu, Xiaodong Tao, Marc Reinig, and Joel Kubby, "Generation of Multispot PSF for Scanning Structured Illumination via Phase Retrieval," Mathematical Problems in Engineering, vol. 2016 [0051]
• R.W. Gerchberg, W.O. Saxton, "A practical algorithm for the determination of the phase of image and diffraction plane pictures," Optics 35, 237 (1972) [0051]
• Wu, Liang & Cheng, Shubo & Tao, Shaohua. (2015) [0051]

Claims (8)

Device for processing materials by means of laser radiation, comprising a laser radiation source (5) which emits pulsed laser radiation (6) for interaction with the material (17), exposing the pulsed processing laser radiation (6) into the material (17) to an interaction center (19) focusing optics (18), one of the position of the interaction center (19) in the material (17) adjusting scanning device (8,8a), wherein each machining laser pulse in an area surrounding its associated interaction center (19) zone interacts with the material (17) in that in the interaction zones material (17) is changed, and preferably a control device (11) which controls the scanning device (8,8a) and the laser radiation source (S) in such a way that in the material (5) through a plurality of interaction zones Cut surface (22,23) arises, characterized in that the Fluence each machining laser pulse is preferably above a threshold above which a optisc Breakthrough in the material (17) is brought about and (1) the distances of the interaction centers (19) and / or the time sequence of the laser pulses take into account the sound propagation in the material (17), or (2) the distances of the interaction centers (19) and / or the time sequence of the laser pulses are adjusted so that they develop a sound effect mediated joint effect in the material (17). Device after Claim 1 , characterized in that the machining laser pulse fluence F is greater than 5 J / cm ² . Device according to one of the above claims, characterized in that the distance Δx between the individual interaction centers (19) corresponds to the distance corresponding to a sound wave in the material in the time Δt between successive laser pulses. Device according to one of Claims 1 or 2 , characterized in that the distance Δx between the individual interaction centers (19) is selected such that the sound waves in the material between adjacent interaction centers amplify so that a material-separating effect occurs. Method for processing materials by means of laser radiation, in which pulsed laser radiation (6) is produced, focused on interaction (17) on interaction centers (19), and the position of the interaction centers (19) in the material (17) is adjusted, whereby each processing In a zone surrounding the interaction center (19), the laser pulse interacts with the material (17), so that material (17) is preferably separated in the interaction zones, and preferably a cut surface (22, 23) in the material (17) by juxtaposing Interaction zones is generated, characterized in that the Fluence each machining laser pulse is preferably above a threshold above which an optical breakdown in the material (17) is effected and that (1) the distances of the interaction centers and / or the time sequence of the laser pulses Consider sound propagation in the material (17) or that (2) the distances of the interaction ntren (19) and / or the time sequence of the laser pulses are set so that they develop a sound wave mediated joint effect in the material (17). Method according to Claim 5 , characterized in that the machining laser pulse fluence F is greater than 5 J / cm ² . Method according to one of Claims 5 or 6 , characterized in that the distance Δx between the individual interaction centers (19) corresponds to the distance corresponding to a sound wave in the material in the time Δt between successive laser pulses. Method according to one of Claims 5 or 6 , characterized in that the distance Δx between the individual interaction centers (19) is selected such that the sound waves in the material between adjacent interaction centers amplify so that a material-separating effect occurs.

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