SYSTEM FOR CUTTING EYE TISSUE INTO BASIC PORTIONS

Abstract

The invention relates to a cutting apparatus comprising a femtosecond laser source for emitting a Gaussian laser beam, a shaping system including a spatial light modulator for modulating the Gaussian laser beam, an optical scanning system for moving the modulated laser beam, and an optical focusing system for focusing the modulated laser beam. It is notable in that the processing device further comprises a control unit for operating the femtosecond laser source, the shaping system, the optical scanning system, and the optical focusing system, in order to produce first and second sets of vertical cutting planes (V1, V2) separated by a horizontal cutting plane (H2). The vertical planes (V2) of the second set are laterally offset relative to the vertical planes (V1) of the first set. Figure to be published with the abstract: Fig. 15

Description

Title of the invention: SYSTEM FOR CUTTING EYE TISSUE INTO ELEMENTARY PORTIONS FIELD OF THE INVENTION

[0001] The present invention relates to the technical field of surgical operations performed with the femtosecond laser, and more particularly to that of ophthalmic surgery, especially for applications of cutting corneas or lenses.

[0002] The invention relates to a device for cutting human or animal tissue, such as a cornea or a lens, using a femtosecond laser source.

[0003] By femtosecond laser source, we mean a light source, capable of emitting a laser beam in the form of ultra-short pulses, the duration of which is between 1 femtosecond and 100 picoseconds, preferably between 1 and 1000 femtoseconds, in particular on the order of a hundred femtoseconds.

[0004] BACKGROUND OF THE INVENTION

[0005] In the context of certain surgeries, such as cataract surgery, it is desirable to subdivide a tissue, such as the lens C - into small particles such as cubes 108 to facilitate its extraction, for example to the area of ​​an aspiration cannula CA, as illustrated in [Fig.1].

[0006] To partition the lens into cubes 108 that can be aspirated by an aspiration cannula, horizontal cutting planes 104a, 104b and vertical cutting planes 107 can be formed, as illustrated in [Fig. 2]. These planes are formed by starting with the horizontal cutting plane 104a deepest in the lens and stacking successive vertical cutting planes 107 and horizontal cutting planes 104b up to the most superficial horizontal cutting plane in the lens.

[0007] Document WO 2022 / 090408 describes, in particular, a cutting apparatus for producing horizontal and vertical cutting planes. This cutting apparatus comprises: • a femtosecond laser source to emit a Gaussian laser beam in the form of pulses, • a shaping system positioned downstream of the laser source to modulate the phase of the wavefront of the Gaussian laser beam, the shaping system comprising a spatial light modulator (SLM) and being configured to produce a modulated laser beam from the Gaussian laser beam, • an optical scanning scanner positioned downstream of the shaping system to move the modulated laser beam, • an optical focusing system downstream of the scanning optical scanner, to focus the modulated laser beam into a focal plane of the cutting device and to move the focal plane into a plurality of positions along an optical axis of propagation of the modulated laser beam, • a control unit configured to drive the femtosecond laser source, the shaping system, the optical scanning system, and the optical focusing system, in order to perform successive horizontal and vertical cutting planes.

[0008] With reference to [Fig.3], the operating principle of such a cutting device is as follows.

[0009] In a first step, an initial horizontal cutting plane 104a (i.e., the deepest) is created. The control unit: • applies a multi-point phase mask to the shaping system to produce a multi-point modulated laser beam, enabling the simultaneous generation of multiple impact points, • controls the movement of the focusing system to align the focal plane of the cutting device with the desired initial cutting plane, • activates the femtosecond laser source, and • controls the movement of the scanning optical scanner along the optical path (e.g., in a zigzag pattern).

[0010] A series of shots is performed in the focal plane of the cutting device. With each shot, several impact points—forming a pattern—focus simultaneously in the focal plane. Each impact point forms a gas bubble. The optical scanner allows the multi-point modulated laser beam—and therefore the pattern—to be moved within the focal plane between each shot. When the entire surface of the horizontal cutting plane is covered with gas bubbles, the initial horizontal cutting plane 104a is finalized.

[0011] In a second step, several adjacent vertical cutting planes 107a are made. For each vertical cutting plane, the control unit: • applies a conical phase mask (i.e., allowing the application of linear phase modulation with rotational symmetry) to the shaping system to produce a Bessel modulated laser beam, • controls the movement of the focusing system to focus the modulated laser beam to a desired depth, • activates the femtosecond laser source, and • controls the movement of the scanning optical scanner along the optical path (e.g., a segment).

[0012] A series of shots is performed. With each shot, an impact line is formed. Each impact line generates an oblong gas bubble along the optical axis of propagation of the Modulated laser beam. The optical scanner allows the modulated laser beam—and therefore the impact line—to be moved between each shot. If the depth of the impact line is less than the desired depth for the vertical cutting plane, then the control unit 60 can control the focusing optical system 50 to vary the depth of the focal plane of the cutting device.

[0013] The vertical cutting planes 107a are completed when the entire path of displacement is covered with oblong gas bubbles.

[0014] The steps for making horizontal planes 104b, 104c, 104d and vertical planes 107b, 107c are repeated to make a stack of crystalline cubes 108.

[0015] When the multitude of gas bubbles has been formed in the different horizontal and vertical planes, the crystalline cubes thus formed can be detached from the uncut tissue portions by detaching the existing tissue bridges between the gas bubbles using a tool.

[0016] However, the formation of stacked cubes 108 induces the accumulation of gas in the upper part of the stack of planes, as illustrated in [Fig. 4]. More specifically, as stacked cubes 108 are formed, the gas bubbles 109 formed in the depth of the tissue 2 move towards the most superficial region of the tissue.

[0017] This gas accumulation can rise above the laser cutting plane in the tissue—for example, in the anterior chamber of the eye in the case of lens cutting. This can lead to problems with laser beam penetration into the tissue. Indeed, the gas bubbles form an opaque bubble barrier that prevents the propagation of energy from the laser beam beneath them, and therefore prevents tissue cutting in the regions located below this gas accumulation.

[0018] This accumulation of gas can also cause deformation of the fabric during cutting which can induce a defect in the sizing of the cubes making aspiration of them from a cannula difficult.

[0019] An object of the present invention is to provide a device for cutting human or animal tissue that avoids the formation of an accumulation of gas that could prevent the propagation of the energy of the laser beam under said accumulation.

[0020] More specifically, an object of the present invention is to provide a cutting device that allows for a complete cutting of a tissue - in particular of an ocular tissue such as a cornea or a lens - while avoiding masking of the laser beam during the cutting.

[0021] Another object of the present invention is to provide a device for cutting human or animal tissue that allows for the formation of tissue cubes of more homogeneous sizes.

[0022] BRIEF DESCRIPTION OF THE INVENTION

[0023] To this end, the invention proposes an apparatus for cutting human or animal tissue, said apparatus including a femtosecond laser source configured to emit a Gaussian laser beam in the form of pulses and a Gaussian laser beam processing device, the processing device being disposed downstream of the femtosecond laser source, the processing device comprising: • a shaping system positioned on the path of the Gaussian laser beam, to modulate the phase of the wavefront of the Gaussian laser beam, the shaping system comprising a spatial light modulator and being configured to produce a modulated laser beam from the Gaussian laser beam, • an optical scanning scanner positioned downstream of the shaping system to move the modulated laser beam, • an optical focusing system downstream of the shaping system, for focusing the modulated laser beam into a focal plane of the cutting device and for moving the focal plane of the cutting device to a plurality of positions along an optical axis of propagation of the modulated laser beam, notable in that the processing device further comprises a control unit for operating the femtosecond laser source, the shaping system, the scanning optical scanner, and the optical focusing system in order to produce successive horizontal and vertical cutting planes, the horizontal cutting planes extending perpendicular to the optical axis and the vertical cutting planes extending parallel to the optical axis, said control unit being configured to: • order the creation of a first horizontal cutting plan, • order the creation of a first plurality of vertical cutting planes above the first horizontal cutting plane, • order the creation of a second horizontal cutting plane above the first plurality of vertical cutting planes, the first horizontal cutting plane being deeper in the fabric than the second horizontal cutting plane, • command the realization of a second plurality of vertical planes above the second horizontal plane, in which the second plurality of vertical cutting planes is laterally offset (in at least one direction perpendicular to the optical axis) relative to the first plurality of vertical planes.

[0024] In the context of the present invention, the term "horizontal cutting plane" means a plane located in the fabric to be treated and extending perpendicularly to the optical axis. of propagation of the laser beam from the cutting device.

[0025] In the context of the present invention, the term "vertical cutting plane" means a plane located in the fabric to be treated and extending parallel to an optical axis of propagation of the laser beam from the cutting device.

[0026] In the context of the present invention, "point of impact" means a specific area of ​​the laser beam contained in the focal plane of the cutting device and in which the intensity of the laser beam is sufficient to generate a gas bubble in a tissue.

[0027] In the context of the present invention, the term "impact line" means a linear area of ​​the laser beam extending perpendicularly to the focal plane of the cutting device (i.e., a segment of the laser beam extending parallel to the optical axis) and in which the intensity of said laser beam is sufficient to generate an oblong gas bubble in the tissue.

[0028] In the context of the present invention, "adjacent impact points" means two impact points arranged opposite each other and not separated by another impact point.

[0029] The term "neighboring impact points" means two points in a group of adjacent points between which the distance is minimal.

[0030] In the context of the present invention, the term “pattern” means a plurality of laser impact points generated simultaneously.

[0031] Thus, the invention makes it possible to generate several groups of vertical cutting planes separated by horizontal cutting planes to form elementary tissue cubes that can be aspirated by a suction cannula. Advantageously, each group of vertical cutting planes is laterally offset relative to the adjacent groups of vertical cutting planes.

[0032] In particular, each group is defined by a plurality of vertical cutting planes formed between two horizontal cutting planes. Assuming three superimposed horizontal cutting planes are provided in the fabric, namely: • a deep horizontal cutting plane, • an intermediate horizontal cutting plane, and • a shallow horizontal cutting plane, Then two groups of vertical cutting planes are formed between the horizontal cutting planes: • a first group of vertical cutting planes is formed between the deep horizontal cutting plane and the intermediate horizontal cutting plane, and • a second group of vertical planes is formed between the intermediate cutting plane and the surface cutting plane, the vertical cutting planes of the second group being laterally offset relative to the planes of vertical cutouts of the first group.

[0033] This lateral offset between vertical cutting planes of adjacent group makes it possible to prevent the gas contained in the gas bubbles formed in a group of vertical cutting planes from propagating towards the gas bubbles formed in an adjacent group of more superficial vertical cutting planes, as will be shown from the description that follows.

[0034] Optical phase modulation is achieved using a phase mask. The energy of the incident laser beam is conserved after modulation, and beam shaping is achieved by acting on its wavefront. The phase of an electromagnetic wave represents the instantaneous state of its amplitude. Phase depends on both time and space. In the case of spatial shaping of a laser beam, only the spatial variations of the phase are considered.

[0035] The wavefront is defined as the surface of points in a beam having an equivalent phase (i.e., the surface consisting of points whose travel times from the source emitting the beam are equal). Modifying the spatial phase of a beam therefore involves modifying its wavefront.

[0036] In the context of the present invention, phase modulation of the wavefront makes it possible to generate a single modulated laser beam which forms: • either several impact points only in the cutting plane (used to form a horizontal cutting plane); in this case, the modulated laser beam is unique throughout the propagation path, the phase modulation of the wavefront allowing the phase of the different points on the beam surface to be delayed or advanced relative to the initial wavefront so that each of these points achieves constructive interference at N distinct points in the focal plane of a lens, the redistribution of energy into a plurality of impact points taking place only in a single plane (i.e. the focal plane) and not along the propagation path of the modulated laser beam. • either an impact line perpendicular to the focal plane of the cutting device (used to form a vertical cutting plane).

[0037] Preferred but not limiting aspects of the cutting apparatus are as follows: • the second plurality of vertical cutting planes can be offset laterally from the first plurality of vertical cutting planes by a distance between 5pm and 500pm; • the second plurality of vertical cutting planes can be offset laterally with respect to the first plurality of vertical cutting planes along first and second axes perpendicular to the optical axis, the first and second axes being orthogonal to each other; For the execution of each horizontal cutting plan, the control unit can be configured to: • apply a multi-point phase mask to the shaping system to produce a single multi-point modulated laser beam, the multi-point phase mask being calculated to distribute the energy of the multi-point modulated laser beam into at least two impact points in the focal plane of the cutting device, • control the movement of the focusing system to align the focal plane of the cutting device with the desired depth for the horizontal cutting plane, • control the optical scanning system to move the impact points of the single multi-point modulated laser beam along an initial displacement path, • activate the femtosecond laser source; For the execution of each vertical cutting plan of the first plurality, the control unit can be configured to: • apply to the shaping system an axiconic modulation instruction in order to produce a Bessel-type modulated laser beam from the Gaussian laser beam, said modulation instruction comprising a phase mask emulating an axicon applied to the spatial light modulator, said Bessel-type modulated laser beam creating an impact line enabling the generation of an oblong gas bubble in the tissue, • to control the optical scanning scanner to move the impact line of the Bessel-type modulated laser beam along a second optical displacement path to form a set of adjacent oblong gas bubbles; For the execution of each vertical cutting plan of the second plurality, the control unit is configured to: • apply the axiconic modulation instruction to the shaping system, • to control the optical scanning scanner to move the impact line of the Bessel-type modulated laser beam along a third optical path offset laterally relative to the second optical path; Each vertical cutting plane consists of a stack of several sets of adjacent oblong gas bubbles, the control unit (60) being configured to: • to control the optical focusing system in order to position the focal plane of the cutting device at a non-zero predefined distance from the first horizontal cutting plane, said predefined distance being less than the length of the impact line of the modulated Bessel-type laser beam so that the impact line partially intersects the first horizontal cutting plane, • to control the optical scanning scanner to move the impact line of the Bessel-type modulated laser beam to form an initial set of adjacent oblong gas bubbles, • to control the optical focusing system in order to position the focal plane of the cutting device at the predefined distance from the first set of adjacent oblong gas bubbles so that the line of impact partially intersects the first set of adjacent oblong gas bubbles, • control the optical scanning scanner to move the impact line of the Bessel-type modulated laser beam to form a second set of adjacent oblong gas bubbles; • The predefined distance can be between 1 / 5 and 1 / 3 of the length of the impact line.

[0038] The invention also relates to a method for cutting a tissue, for example, previously harvested human or animal tissue, using a cutting device comprising: • a femtosecond laser source configured to emit a Gaussian laser beam in the form of pulses, • a shaping system downstream of the femtosecond laser source and positioned on the path of the Gaussian laser beam, to modulate the phase of the wavefront of the Gaussian laser beam, the shaping system comprising a spatial light modulator and being configured to produce a modulated laser beam from the Gaussian laser beam, • an optical scanning scanner positioned downstream of the shaping system to move the modulated laser beam, • an optical focusing system downstream of the shaping system, to focus the modulated laser beam into a focal plane of the cutting device and to move the focal plane of the cutting device to a plurality of positions along an optical axis of propagation of the modulated laser beam, notable in that the cutting process includes a phase of creating successive horizontal and vertical cutting planes by controlling the femtosecond laser source, the shaping system, the scanning optical scanner, and the system focusing optics, the horizontal cutting planes extending perpendicularly to the optical axis and the vertical cutting planes extending parallel to the optical axis, said implementation phase comprising the steps of: • to create a first horizontal cutting plan, • to form, above the first horizontal cutting plane, a first plurality of vertical cutting planes, • to form, above the first plurality of vertical cutting planes, a second horizontal cutting plane, the first horizontal cutting plane being deeper in the fabric than the second horizontal cutting plane, • form, above the second horizontal plane, a second plurality of vertical planes offset laterally relative to the first plurality of vertical planes.

[0039] Preferred but not limiting aspects of the method according to the invention are as follows: • the second plurality of vertical cutting planes can be offset laterally from the first plurality of vertical cutting planes by a distance between 5pm and 500pm; • the second plurality of vertical cutting planes can be offset laterally with respect to the first plurality of vertical cutting planes along first and second axes perpendicular to the optical axis, the first and second axes being orthogonal to each other; • Each step in forming a horizontal cutting plan may include the following sub-steps: • application of a multi-point phase mask to the shaping system to produce a single multi-point modulated laser beam, the multi-point phase mask being calculated to distribute the energy of the multi-point modulated laser beam into at least two impact points in the focal plane of the cutting device, • displacement by the focusing system of the focal plane of the cutting device to the desired depth for the horizontal cutting plane, • displacement by the optical scanner of the impact points of the single multi-point modulated laser beam along a first displacement path, and • emission of a Gaussian laser beam by the femtosecond laser source; • Each step in forming a vertical cutting plane of the first plurality may include the following substeps: • application of an axiconic modulation instruction to the shaping system in order to produce a Bessel-type modulated laser beam, said modulation instruction comprising a phase mask emulating an axicon applied to the spatial light modulator, said phase mask having rotational symmetry around a central point of symmetry, the grey level of each point of the phase mask varying according to the distance between said point and the central point of symmetry, said Bessel-type modulated laser beam creating an impact line enabling the generation of an oblong gas bubble in the tissue, • displacement by the optical scanning scanner of the impact line of the modulated Bessel type laser beam along a second optical displacement path to form a set of adjacent oblong gas bubbles; Each step in forming a vertical cutting plane of the second plurality may include the following substeps: • application of the axiconic modulation instruction to the shaping system, • displacement by the scanning optical scanner of the impact line of the modulated Bessel type laser beam along a third optical path of displacement offset laterally relative to the second optical path; Each vertical cutting plane can be composed of a stack of several sets of adjacent oblong gas bubbles, each step in forming a vertical cutting plane comprising the following substeps: • displacement by the optical focusing system of the focal plane of the cutting device to a non-zero predefined distance from the first horizontal cutting plane, said predefined distance being less than the length of the impact line of the modulated Bessel-type laser beam such that the impact line partially intersects the first horizontal cutting plane, • displacement by the optical scanning system of the impact line of the Bessel-type modulated laser beam to form a first set of adjacent oblong gas bubbles, • displacement by the optical focusing system of the focal plane of the cutting device to the predefined distance from the first set of adjacent oblong gas bubbles so that the line of impact partially intersects the first set of adjacent oblong gas bubbles, • displacement by the optical scanning scanner of the impact line of the modulated Bessel type laser beam to form a second set of adjacent oblong gas bubbles; • The predefined distance can be between 1 / 5 and 1 / 3 of the length of the impact line. Brief description of the drawings

[0040] Other features and advantages of the invention will become clear from the description given below, by way of example and not limitation, with reference to the accompanying figures, in which:

[0041] [Fig-1] is a schematic representation of a patient's eye,

[0042] [Fig.2] is a schematic representation of gas bubbles created to form basic fabric cubes from horizontal and vertical cutting plans,

[0043] [Fig.3] is a schematic representation of a stack of horizontal and vertical cutting planes obtained using the cutting device described in WO 2016 / 055539,

[0044] [Fig.4] is a schematic representation illustrating an accumulation of gas following the formation of superimposed vertical cutting planes from the cutting apparatus described in WO 2016 / 055539,

[0045] [Fig.5] is a schematic representation of a cutting device according to the invention,

[0046] [Fig.6] is a schematic representation illustrating the focusing of a non-diffracting Bessel-type beam,

[0047] [Fig.7a] is an image of a first phase mask allowing emulation of the behavior of a negative axicon on an SLM of the cutting device according to the invention,

[0048] [Fig.7b] is an image of a second phase mask allowing emulation of the behavior of a positive axicon on the SLM of the cutting device according to the invention,

[0049] [Fig.8] is a partial assembly diagram of the cutting device,

[0050] [Fig.9] is a schematic representation of a Bessel beam,

[0051] [Fig. 10] is a schematic representation of control steps during the realization of a horizontal cutting plane,

[0052] [Fig. 11] is a schematic representation of control steps during the execution of a vertical cutting plan,

[0053] [Fig. 12] is a schematic representation illustrating the formation of a vertical cutting plane from a Bessel laser beam,

[0054] [Fig. 13] is a schematic representation illustrating a set of impact lines used to create stacked oblong pans of gas bubbles,

[0055] [Fig. 14] is a schematic representation of control steps during the execution of successive horizontal and vertical cutting plans,

[0056] [Fig. 15] is a schematic representation of horizontal and vertical cutting planes made successively. DETAILED DESCRIPTION OF THE INVENTION

[0057] The invention relates to a system for cutting human tissue using a femtosecond laser. In the following description, the invention will be described, by way of example, for cutting the lens of a human or animal eye.

[0058] 1. Cutting device

[0059] With reference to [Fig. 5], an embodiment of the cutting device according to the invention is illustrated. This can be arranged between a femtosecond laser source 10 and a target to be treated 2.

[0060] The femtosecond laser source 10 is capable of emitting a Gaussian laser beam in the form of pulses. For example, the femtosecond laser source 10 emits light with a wavelength of 1030 nm, in the form of 400 femtosecond pulses. The femtosecond laser source 10 has a power of 20 W and a frequency of 500 kHz.

[0061] Target 2 is for example a human or animal tissue to be cut such as a cornea or a lens.

[0062] The cutting device comprises: • a shaping system 30 positioned on the path of the laser beam 110 from the femtosecond laser 10, • an optical scanning scanner 40 downstream of the shaping system 30, • an optical focusing system 50 downstream of the optical scanning scanner 40, and • a control unit 60.

[0063] The shaping system 30 allows the phase of the laser beam 110 from the femtosecond laser source 10 to be modulated. This shaping system 30 is advantageously a programmable component.

[0064] The optical scanning scanner 40 allows the phase-modulated laser beam 310 from the shaping system 30 to be directed to move the cutting pattern along a user-defined path in the focal plane 101 of the cutting system.

[0065] The optical focusing system 50 allows the focal plane 101 - corresponding to the cutting plane - of the modulated and deflected laser beam 410 to be moved.

[0066] The control unit 60 allows the shaping system 30 to be controlled, the optical scanning scanner 40 and optical focusing system 50.

[0067] This cutting device is suitable for forming horizontal and vertical cutting planes. Depending on the type of cutting plane desired (vertical or horizontal), the control unit 60: • configures the shaping system to modulate the 110 laser beam according to the desired appearance for the impact points / lines, and • controls the optical scanning scanner 40 and the optical focusing system 50 to generate the desired cutting plan.

[0068] As will be described in more detail later, the inventors have developed an original configuration solution for the cutting device for the formation of vertical cutting planes.

[0069] 2. Elements of the cutting device

[0070] 2.1. Formatting system

[0071] The spatial shaping system 30 of the laser beam allows the wavefront of the laser beam 110 to be varied according to the desired shape: • for the point(s) of impact of the modulated laser beam in the case of the formation of a horizontal cutting plane, or • for the impact line(s) of the modulated laser beam in the case of the formation of a vertical cutting plane.

[0072] The shaping system 30 preferably includes a spatial light modulator, known by the acronym SLM, from the English acronym "Spatial Light Modulator".

[0073] The SLM allows modulation of the final energy distribution of the laser beam 110 from the laser source 10. The SLM is a device consisting of a layer of liquid crystals with controlled orientation, enabling dynamic shaping of the wavefront, and therefore the phase, of the laser beam 110. The liquid crystal layer of an SLM is organized as a grid (or matrix) of pixels. The optical thickness of each pixel is electrically controlled by the orientation of the liquid crystal molecules belonging to the surface corresponding to the pixel. The SLM exploits the principle of liquid crystal anisotropy, that is, the modification of the refractive index of the liquid crystals as a function of their spatial orientation. The orientation of the liquid crystals can be achieved using an electric field. Thus, modifying the refractive index of the liquid crystals modifies the wavefront of the laser beam.

[0074] In a known manner, the SLM implements a phase mask, that is, a map determining how the phase of the laser beam 110 must be modified to obtain a given amplitude distribution. The phase mask is a two-dimensional image in which each point is associated with a respective pixel of the SLM. This phase mask allows the index of each liquid crystal of the SLM to be controlled by converting the value associated with each point of the mask—represented in shades of gray—into a specific range. between 0 and 255 (i.e., from black to white) – in a control value – represented by a phase between 0 and 2ir. Thus, the phase mask is a modulation setting displayed on the SLM to induce, upon reflection, an unequal spatial phase shift of the laser beam illuminating the SLM. Of course, those skilled in the art will appreciate that the grayscale range can vary depending on the SLM model used. For example, in some cases, the grayscale range can be between 0 and 220.

[0075] Different phase masks can be applied to the SLM depending on the type of cutting plan the user wishes to produce, namely: • either a vertical cutting plan, • either a horizontal cutting plan.

[0076] For the creation of a vertical cutting plane, the phase mask used (hereinafter referred to as the "conical phase mask") allows for the application of linear phase modulation with rotational symmetry. This results in a modulated laser beam of the Bessel type.

[0077] For creating a horizontal cutting plane, the phase mask used (hereinafter referred to as the "multipoint phase mask") allows for the application of phase modulation to distribute the energy of the laser beam into at least two impact points forming a pattern in the focal plane of the cutting system. This results in a modulated multipoint laser beam.

[0078] 2.1.1. Vertical cutting plane

[0079] With regard to the cutting of a vertical plane, the inventors propose to modulate the phase of the laser beam 110 from the femtosecond laser source 10 so as to produce, downstream of the shaping system 30, a modulated laser beam 310 of the Bessel type.

[0080] A Bessel beam is said to be "non-diffracting" because it has the property of keeping a constant profile along the optical axis of propagation of the laser beam (hereinafter referred to as "optical axis"), unlike the behavior of a Gaussian laser beam (such as the laser beam 110 from the femtosecond laser source 10) which disperses when focused.

[0081] 2.1.1.1. Bessel beam

[0082] A perfect zero-order Bessel beam can be mathematically defined as a beam whose electric field (E) is formally described by the zero-order Bessel function of the first kind Jo:

[0083] E(r, Phi, z) A0J0(krr)^kzz

[0084] where: • Ao is the amplitude of the electric field, • kz and kr are the longitudinal and radial wave vectors, • z, r, and Phi are the longitudinal, radial, and azimuthal components.

[0085] With reference to [Fig.6], the formation of the Bessel beam 313 results from the interference of plane waves whose wave vectors form a conical surface.

[0086] In theory, the transverse extension of the annular structure is infinite, as is the non-diffractive propagation distance.

[0087] In practice, the experimental Bessel beam exhibits a finite non-diffractive propagation distance ZB along the optical axis due to the finite propagation observed in optics and the limited amount of energy. This finite non-diffractive propagation distance ZB defines a non-diffraction zone ZND.

[0088] It is assumed that ZB » ZR, where ZR is the Rayleigh distance of the usual Gaussian beam of similar transverse size. In other words, the depth (i.e., dimension along a direction parallel to the optical axis of propagation of the laser beam) of each point of impact of a Bessel beam is much greater than the depth of each point of impact with a Gaussian laser beam (such as the laser beam from the femtosecond laser source).

[0089] Thus, the use of a Bessel beam makes it possible to cut a much greater depth of tissue than with a Gaussian beam. In particular, from a single point of impact of a Bessel beam, it is possible to cut tissue to a depth equivalent to that of four superimposed points of impact of a Gaussian beam. The displacement, by the scanning optical scanner, of the point of impact of a Bessel beam makes it possible to generate a perfectly vertical cutting plane four times faster than with a point of impact of a Gaussian beam.

[0090] Due to its specific formation based on a conical wavefront, the Bessel beam exhibits remarkable self-regeneration properties, meaning that the beam can regenerate itself within the non-diffraction zone (NDZ) after encountering any obstacle in its path. This ensures the quality of vertical plane cutting by guaranteeing the formation of an extended gas bubble with each shot of the laser source 10, even when part of the modulated laser beam 310 is obscured by an obstacle.

[0091] 2.1.1.2. Conical phase mask for forming a modulated laser beam of type Bessel

[0092] There are various techniques for generating a Bessel beam from a Gaussian laser beam. These techniques generally involve axiconic phase modulation.

[0093] In particular, the Bessel beam can be obtained using a conical lens known as an "axicon". The conical lens can be concave / hollow (referred to as a "negative axicon") or convex / domed (referred to as a "positive axicon").

[0094] The inventors propose to use the 30 shaping system including the SLM to generate the Bessel beam in order to avoid the use of an optical / mechanical element. For this purpose, a conical phase mask (allowing the emulation of an axicon) is applied to the SLM by the control unit 60. The SLM then enables conical phase modulation of the Gaussian laser beam 110 from the femtosecond laser source 10. Thus, using the same SLM, it becomes possible to perform a multi-point horizontal cutting plane, then vertical cutting planes in Bessel beam mode without changing optical elements, and therefore considerably reducing the surgical procedure time to between 30 seconds and 1 minute, compatible with an application on the patient's eyeball of less than 3 minutes.

[0095] The conical phase mask to be applied to the SLM of the shaping system to form a Bessel modulated laser beam can be calculated: • using a partitioning algorithm (Vellekoop and Mosk, 2008), • or any other algorithm known to a person skilled in the art.

[0096] Two examples of such phase masks are illustrated in Figures 7a and 7b. When one of the first and second phase masks is applied to the SLM, the SLM is able to print the phase profile of an axicon onto the input Gaussian laser beam 110 to obtain a Bessel-type modulated laser beam 310 at the output of the shaping system 30.

[0097] With reference to [Fig. 7a], the first conical phase mask (reference 314) emulates the behavior of a negative axicon (i.e., a concave axicon). With reference to [Fig. 7b], the second conical phase mask (reference 315) emulates the behavior of a positive axicon (i.e., a convex axicon). These first and second phase masks each exhibit rotational symmetry about a central point of symmetry, with the gray level of each pixel varying according to the distance between said pixel and the central point of symmetry.

[0098] When one of the phase masks illustrated in Figures 7a and 7b is applied to the SLM, the shaping system 30 makes it possible to form a modulated Bessel-type laser beam 310 (at the output of the shaping system 30) from the Gaussian laser beam 110 from the femtosecond laser source 10 (at the input of the shaping system 30). This yields a modulated laser beam exhibiting a spatial intensity distribution in the form of a Bessel beam.

[0099] 2.1.1.3. Mounting the cutting device in the context of cutting a fabric starting from a modulated Bessel-type laser beam

[0100] A diagram of the cutting apparatus assembly is shown in [Fig. 8]. This diagram is incomplete in that it does not show the femtosecond laser source and the optical scanning unit. Furthermore, in this [Fig. 8], the focusing optical system 50 (as a whole) is represented by an equivalent lens 51, being It is obvious to a person skilled in the art that the 50 focusing optical system does not consist solely of a fixed lens.

[0101] With reference to [Fig.8], the Bessel beam 313 is formed just after the conical phase modulation plane, i.e. just after the SLM of the shaping system 30. The SLM simulating a conical lens (negative or positive axicon), the central spot of maximum intensity of the Bessel beam is formed in the image focal plane 32 of the SLM.

[0102] The equivalent lens 51 of the focusing optical system 50 is disposed downstream of the shaping system 30, and is arranged so that the object focal plane 52 of the equivalent lens extends to a non-zero distance from the image focal plane 32 of the shaping system 30 along the optical axis.

[0103] Thus, the object focal plane 52 of the equivalent lens 51 of the focusing optical system 50 extends outside the non-diffraction zone ZND of the Bessel beam, so that at the output of the cutting system, an impact line as illustrated in [Fig. 9] is obtained. More precisely, the Bessel beam is composed of: • of a Bessel ring 33a focused at the image focal plane 53 of the equivalent lens 51 (corresponding to the focal plane of the cutting device), • of a line 33b of concentration of the rays of the Bessel beam - corresponding to the image of the non-diffraction zone ZND - said line 33b forming outside the image focal plane 53 of the equivalent lens 51.

[0104] In the context of the present invention, it is line 33b which constitutes the impact line used to make the vertical cutting plane (the energy contained in the Bessel ring is not sufficient to form a gas bubble).

[0105] Line 33b can be formed either before or after ring 33a, depending on the sign of the phase modulation. In other words, the position of line 33b relative to ring 33a depends on the type of axicon (positive or negative) emulated by the conical phase mask.

[0106] Since the Bessel non-diffraction zone (NDZ) (i.e., line 33b) is moved outside the focal plane of the cutting system, no interference occurs with the unmodulated light. This allows for better control of the intensity profile without energy loss due to beam filtering.

[0107] 2.1.2. Horizontal cutting plane

[0108] With regard to the cutting of a horizontal plane, the inventors propose to modulate the phase of the laser beam 110 from the femtosecond laser source 10 so as to produce, downstream of the shaping system 30, a modulated multipoint type laser beam.

[0109] To this end, a multipoint phase mask to be applied to the SLM to obtain the multipoint modulated laser beam is calculated. The multipoint phase mask is generated generally calculated by: • an iterative algorithm based on the Fourier transform, such as an algorithm of the type "1FTA", an acronym for the Anglo-Saxon expression "Iterative Fourier Transform Algorithm", or by • various optimization algorithms, such as genetic algorithms, or simulated annealing.

[0110] This multipoint phase mask is calculated to form intensity peaks in the focal plane of the cutting device, each intensity peak producing a respective impact point in the focal plane of the cutting device.

[0111] More specifically, the multipoint phase mask is calculated to distribute the energy of the laser beam from the laser source into several impact points—forming a pattern—in the focal plane of the cutting device. This wavefront modulation can be viewed as a two-dimensional interference phenomenon. Each portion of the initial laser beam from the source is delayed or advanced relative to the initial wavefront so that each of these portions is redirected to achieve constructive interference at N distinct points in the focal plane of a lens. This energy redistribution into a plurality of impact points occurs only in a single plane (i.e., the focal plane) and not along the entire propagation path of the modulated laser beam.Thus, the multipoint laser beam obtained (at the output of the shaping system 30) is unique: observation of the modulated laser beam before or after the focal plane of the cutting device (corresponding to the focal plane of the focusing optical system 50) does not allow identification of a redistribution of energy into a plurality of distinct impact points, due to this phenomenon which can be assimilated to constructive interferences (which only take place in one plane and not throughout the propagation as in the case of the separation of an initial laser beam into a plurality of secondary laser beams).

[0112] Having a single multipoint modulated laser beam facilitates the integration of a scanning system—such as an optical scanner—to move the plurality of impact points in the focal plane. Indeed, since the input diameter of a scanning system is on the order of the diameter of the initial laser beam from the laser source 10, the use of a single multipoint modulated laser beam (whose diameter is substantially equal to the diameter of the initial laser beam) limits the risks of aberration that can occur with the beam subdivision technique as described in US 2010 / 0133246.

[0113] The shaping system 30 therefore makes it possible, starting from a Gaussian laser beam generating a single point of impact, and by means of the multipoint phase mask applied to the SLM, to distribute its energy by phase modulation so as to simultaneously generate several points of impact in the focal plane of the cutting device, at starting from a single laser beam shaped by phase modulation (a single beam upstream and downstream of the SLM). This reduces the time required to create a horizontal cutting plane.

[0114] For example, in the case of a multi-point modulated laser beam with three impact points, the time required to create a horizontal cutting plane is reduced by a factor of six (compared to creating the same horizontal cutting plane using a Gaussian laser beam generating a single impact point). Those skilled in the art know how to calculate a value at each point of the multi-point phase mask to distribute the laser beam energy to different impact points in the focal plane of the cutting device.

[0115] 2.2. Optical scanning

[0116] The optical scanning scanner 40 allows the modulated laser beam (Bessel or multipoint) 310 to be deflected so as to move: • for the creation of a horizontal cutting plan, the point(s) of impact in a plurality of positions along a first path of movement, • for the realization of a vertical cutting plan, the impact line(s) in a plurality of positions along a second path of movement.

[0117] The optical scanning scanner 40 comprises: • an inlet port to receive the phase-modulated laser beam 31 from the shaping unit 30, • one (or more) optical mirror(s) pivoting around at least two axes to deflect the phase-modulated laser beam 310, and • an output port to send the deflected modulated laser beam 410 towards the focusing optical system 50.

[0118] The optical scanner 40 used is, for example, an IntelliScan III scanning head from SCANLAB AG.

[0119] The inlet and outlet ports of such an optical scanner 40 have a diameter of the order of 10 to 20 millimeters, and the achievable scanning speeds are on the order of Im / s to 10m / s.

[0120] The mirror(s) is / are connected to one or more motors to allow them to pivot. This / these motor(s) for pivoting the mirror(s) is / are advantageously controlled by the control unit 60, which will be described in more detail later.

[0121] The control unit 60 is programmed to control the optical scanning scanner 40 so as to move: • the point(s) of impact along the first path of travel, • the impact line(s) along the second path of displacement.

[0122] In the case of a horizontal cutting plane, the first path of movement comprises a plurality of cutting segments. The first path of movement may advantageously have a crenellated shape.

[0123] In the case of a vertical cutting plane, the second path of movement comprises a segment. The control unit 60 can be configured to command the optical scanner 40 to move back and forth along the Bessel impact line along said segment to cut the vertical cutting plane to its full depth. For example, if the optical scanner 40 starts the segment on the left, it will start this segment on the right on the return, then on the left, then on the right, and so on over the entire height of the vertical cutting plane.

[0124] The beam scanning has an influence on the result of the cut obtained. Indeed, the scanning speed used, as well as the scanning pitch, are parameters influencing the quality of the cut.

[0125] Advantageously, the control unit 60 can be programmed to activate the femtosecond laser 10 when the scanning speed of the optical scanner 40 exceeds a threshold value. This allows the emission of the laser beam 110 to be synchronized with the scanning speed of the optical scanner 40. More specifically, the control unit 60 activates the femtosecond laser 10 when the pivoting speed of the mirror(s) of the optical scanner 40 is constant. This improves the cutting quality by achieving a homogeneous surface finish on the cutting plane.

[0126] 2.3. Optical focusing system

[0127] The optical focusing system 50 allows the focal plane of the cutting device to be moved according to the type of cutting plane to be produced.

[0128] The focusing optical system 50 comprises: • an inlet port to receive the phase-modulated and deflected laser beam from the optical scanning scanner 40, • one (or more) motorized lens(es) to allow its (their) translational movement along the optical path of the modulated and deflected laser beam, and • an output port to send the focused laser beam to the tissue to be treated.

[0129] The control unit 60 is programmed to control the movement of the lens(es) of the focusing optical system 50 so as to move the focal plane of the cutting device according to the type of cutting plane to be made.

[0130] In the case of a horizontal cutting plane, the cutting plane corresponds to the focal plane of the cutting device. The control unit 60 controls the movement of the lens(es) of the focusing optical system 50 to focus the modulated and deflected laser beam 410 to a desired depth corresponding to the depth of the cutting plan to be created.

[0131] In the case of a vertical cutting plane, the cutting plane may be located: • below the focal plane of the cutting device in the case where the conical phase mask used allows the SLM to emulate a positive axicon (the Bessel ring 33a is located above the impact line used to perform the cutting), • above the focal plane of the cutting device in the case where the conical phase mask used allows the SLM to emulate a negative axicon (the Bessel ring 33a is located below the impact line used to perform the cutting).

[0132] Preferably, the distance between two successive cutting planes is between 2 pm and 500 pm, and in particular: • between 2 and 20 µm to treat a volume requiring high precision, for example in refractive surgery, preferably with a spacing between 5 and 1 µm, or • between 20 and 500pm to treat a volume not requiring high precision, such as for destroying the central part of a crystallinian nucleus, preferably with a spacing between 50 and 300pm.

[0133] Of course, this distance can vary in a volume composed of a stack of cutting planes.

[0134] 2.4. Control unit

[0135] As previously stated, the control unit 60 allows control of the various components of the cutting device, namely the femtosecond laser source 10, the shaping system 30, the scanning optical scanner 40 and the focusing optical system 50.

[0136] The control unit 60 is connected to these various components via one (or more) communication buses enabling: • the transmission of control signals such as • the activation signal to the femtosecond laser source 10, • the phase mask to the shaping system 30, • the scanning speed to the optical scanning scanner 40, • the position of the optical scanning scanner 40 along the path of investment, • the cutting depth at the focusing optical system 50. • the reception of measurement data from the various elements of the system such as • the scanning speed achieved by the optical scanner, or • the position of the optical focusing system, etc.

[0137] The control unit 60 may consist of one (or more) workstation(s), and / or one (or more) computer(s), or may be of any other type known to a person skilled in the art. The control unit 60 may, for example, include a mobile phone, an electronic tablet (such as an iPad®), a personal digital assistant (PDA), etc.

[0138] In all cases, the control unit 60 includes a processor programmed to allow the control of the femtosecond laser source 10, the shaping system 30, the scanning optical scanner 40, the focusing optical system 50, etc.

[0139] Advantageously, the control unit 60 is programmed to vary the shape of the modulated laser beam between two successive cutting planes, in particular between a horizontal cutting plane and a vertical cutting plane.

[0140] 2.5. Operating principle

[0141] We will now describe in more detail the operating principle of the cutting device according to the invention by detailing: • the operation of the device to create a horizontal cutting plane, • the operation of the device to create a vertical cutting plan, • the operation of the device to create a superposition of planes horizontal and vertical stacked cuts.

[0142] 2.5.1. Formation of a horizontal cutting plane

[0143] Within the framework of the present invention, the formation of a horizontal cutting plane is carried out as follows.

[0144] With reference to [Fig. 10], the control unit 60 emits a control signal to the focusing optical system 50 to control its movement so as to make the focal plane of the cutting device coincide with the desired horizontal cutting plane (step El 10).

[0145] The control unit 60 transmits a multi-point phase mask to the shaping system 30 to produce a multi-point modulated laser beam (step El20).

[0146] The control unit 60 also activates the movement of the scanning optical scanner 40 to an initial position of the first scanning optical path. Since the scanning is performed in X, Y, the scanner is equipped with one or more mirrors. For example, in the embodiment illustrated in [Fig. 5], the scanning optical scanner 40 comprises a first X mirror and a second Y mirror, the pivoting of which allows the modulated laser beam to be moved along the first path. Alternatively, the scanner can be equipped with a single mirror configured to pivot about two separate axes.

[0147] When: • the focusing system 50 and the optical scanner 40 are in position (i.e., the scanner has reached a target start-of-line position), that • the multipoint phase mask is loaded into the formatting system 30, and that • The pivoting speed of the mirror(s) of the optical scanner 40 is constant, • The control unit 60 activates the femtosecond laser source 10 to emit a laser pulse (step El30).

[0148] The femtosecond laser source 10 generates a laser beam 110 which passes through the shaping system 30. The shaping system 30 modulates the phase of the laser beam to produce a single multi-point modulated laser beam.

[0149] The multi-point modulated laser beam 310 exits the shaping system 30 and enters the optical scanner 40 which deflects the multi-point modulated laser beam 310.

[0150] The modulated and deflected laser beam 410 enters the focusing optical system 50, which focuses the beam into the focal plane of the cutting device. In the focal plane, the modulation command (i.e., the multipoint phase mask) applied to the shaping system 30 distributes the energy into a plurality of impact points. This plurality of simultaneously generated impact points forms the pattern. Each impact point of the pattern simultaneously produces a gas bubble.

[0151] The femtosecond laser 10 continues to emit further pulses in the form of a laser beam at a determined rate. Between each pulse, the mirror(s) pivot(s) by a certain angle, which results in the displacement of the pattern 8 and the production of new gas bubbles offset relative to the previous ones along the first optical path (step El40).

[0152] The operations of driving the femtosecond laser source 10 and the scanning optical scanner 40 are repeated to form the horizontal cutting plane.

[0153] By varying the speed of movement of the mirror(s) and / or the rate of generation of pulses by the femtosecond laser source 10, it is possible to vary the distance between two successive patterns.

[0154] Once the cutting line has been completed, the control unit 60 deactivates the femtosecond laser source 10, and commands the movement of the optical scanner 40 to a next cutting position according to the first movement path.

[0155] When the optical scanner 40 is in position and the mirror(s) has (have) reached its (their) constant set speed, the control unit 60 reactivates the femtosecond laser source 10. The laser beam 110 passes through the shaping system 30, the optical scanner 40 and the focusing optical system 50. A new line of gas bubbles - parallel to the previous one - forms in the cutting plane.

[0156] When the optical scanner 40 has scanned all positions of the first de- path The horizontal cutting plan is finalized.

[0157] In summary, for the creation of a horizontal cutting plan, the control unit 60 is configured to: • apply a multi-point phase mask to the shaping system 30 to produce a single multi-point modulated laser beam, the multi-point phase mask being calculated to distribute the energy of the multi-point modulated laser beam into at least two impact points in the focal plane of the cutting device, • control the movement of the focusing system 50 to align the focal plane of the cutting device with the desired depth for the horizontal cutting plane, • to control the 40 optical scanning scanner to move the impact points of the single multi-point modulated laser beam along a first displacement path, and • activate the femtosecond laser source 10 (after stabilization of the scanner's movement speed).

[0158] 2.5.2. Formation of a vertical cutting plane

[0159] Within the framework of the present invention, the formation of a vertical cutting plane is carried out as follows.

[0160] With reference to [Fig. 11], the control unit 60 sends a control signal to the focusing optical system 50 to control its movement so as to position the focal plane of the cutting device at a given depth relative to the desired position for the vertical cutting plane (step E210). Indeed, as indicated previously, in the case of a vertical cutting plane, the cutting plane can be located: • above the focal plane of the cutting device if the conical phase mask used allows the SLM to emulate a positive axicon (the Bessel ring 33a is located above the impact line used to perform the cut), in this case the control unit 60 drives the focusing optical system 50 to focus the modulated and deflected laser beam 410 to a desired depth less than the maximum depth of the vertical cutting plane to be made, • below the focal plane of the cutting device in the case where the conical phase mask used allows the SLM to emulate a negative axicon (the Bessel ring 33a is located below the impact line used to perform the cut) in this case the control unit 60 drives the focusing optical system 50 to focus the modulated and deflected laser beam 410 to a desired depth greater than the maximum depth of the cutting plane at realize.

[0161] The control unit 60 transmits a conical phase mask (i.e. axiconic modulation setpoint) to the shaping system 30 to produce a modulated Bessel laser beam (step E220).

[0162] The control unit 60 also activates the movement of the optical scanning scanner 40 to an initial position of the second optical scanning path.

[0163] When: • The focusing system 50 and the optical scanner 40 are in position, • The conical phase mask is loaded into the shaping system 30, and that • The pivoting speed of the mirror(s) of the optical scanner 40 is constant, • The control unit 60 activates the femtosecond laser source 10 to emit a laser pulse (step E230).

[0164] The femtosecond laser source 10 generates a laser beam 110 which passes through the shaping system 30. The shaping system 30 modulates the phase of the laser beam to produce a single modulated Bessel-type laser beam.

[0165] The Bessel 310 type modulated laser beam exits the shaping system 30 and enters the optical scanner 40 which deflects the Bessel 310 type modulated laser beam.

[0166] The modulated and deflected laser beam 410 enters the focusing optical system 50, which focuses the beam. Above or below the focal plane, the modulation setting (i.e., the conical phase mask) applied to the shaping system 30 distributes the energy into an impact line. This impact line produces an oblong gas bubble extending parallel to the optical axis A-A' of the cutting device, as illustrated in step 620a of [Fig. 12].

[0167] The femtosecond laser 1 continues to emit further pulses in the form of a laser beam at a predetermined rate. Between each pulse, the mirror(s) pivot(s) by a certain angle, which results in the displacement of the impact line and the formation of a new oblong gas bubble along the second optical path (step E240). This new gas bubble is adjacent to the previously formed oblong gas bubble, as illustrated in step 620b of [Fig. 12], after a certain number of pulses, thus forming a vertical cutting plane segment.

[0168] The operations of driving the femtosecond laser source 10 and the scanning optical scanner 40 are repeated to form the vertical cutting plane.

[0169] More specifically, the pivoting of the mirror(s) between each pulse of the femtosecond laser source 10 results in the displacement of the impact line and the production of new oblong gas bubbles offset from the previous ones, until a cutting edge is formed in the cutting plane, as illustrated in step 620c of the [Fig. 12].

[0170] Once a cutting panel has been completed, the control unit 60 deactivates the femtosecond laser source 10, and commands the movement of the focusing optical system to produce a second panel of oblong gas bubbles above the first panel, then commands the restart of the pivoting of the mirror(s) in the opposite direction and reactivates the femtosecond laser source 10, as illustrated in step 630c of [Fig.12].

[0171] The laser beam 110 passes through the shaping system 30, the optical scanner 40 and the optical focusing system 50. A new pan of oblong gas bubbles - located above the previous pan and extending in the same plane as the previous pan - is formed in the cutting plane.

[0172] When the optical scanner 40 has scanned all positions of the second travel path, the vertical cutting plane is complete.

[0173] In summary, for the execution of a vertical cutting plan, the control unit 60 is configured to: • apply to the shaping system 30, an axiconic modulation instruction in order to produce a Bessel-type modulated laser beam from the Gaussian laser beam, said modulation instruction comprising a phase mask 314, 315 emulating an axicon applied to the spatial light modulator (SLM), said Bessel-type modulated laser beam creating an impact line enabling the generation of an oblong gas bubble in the tissue, • to control the scanning optical scanner 40 to move the impact line of the Bessel-type modulated laser beam along a second optical displacement path to form a vertical plane consisting of a set of adjacent oblong gas bubbles.

[0174] With reference to [Fig. 13], a set of impact lines L1, L2, L3 used to produce oblong gas bubble panels stacked and extending in the same vertical cutting plane located between two horizontal cutting planes H1, H2 has been partially illustrated.

[0175] As shown in [Fig. 13], the impact lines used to form two successive stacked facets partially overlap. Indeed, the inventors discovered that the end portions of an impact line do not possess sufficient energy to form the oblong gas bubble. Therefore, the inventors propose an overlap of the impact lines used to create stacked oblong gas bubble facets.

[0176] In particular, after the creation of a horizontal cutting plane Hl, the vertical cutting planes located above the horizontal cutting plane Hl are created in stacking successive oblong gas bubble panels, for example first, second and third panels in the embodiment illustrated in [Fig. 13].

[0177] To produce the first section (i.e., the section closest to the horizontal cutting plane Hl), the control unit 60 is configured to drive the focusing optical system 50 to position the focal plane of the cutting device at a predefined, non-zero distance from the first horizontal cutting plane. This predefined distance is less than the length of the impact line L1 of the modulated Bessel laser beam. In particular, the predefined distance can be between 1 / 5 and 1 / 3 of the impact line length. Thus, each impact line L1 used to produce the first section partially intersects the horizontal cutting plane Hl. The control unit 60 then drives the scanning optical scanner 40 to move the impact line L1 along the second optical path to form the first section of adjacent oblong gas bubbles.

[0178] To create the second pane (i.e., the pane located above the first pane), the control unit 60 is configured to drive the focusing optical system 50 to position the focal plane of the cutting device at the predefined distance from the first pane of oblong gas bubbles. Thus, each impact line L2 used to create the second pane partially overlaps the oblong gas bubbles of the first pane. The control unit 60 then drives the scanning optical scanner 40 to move the impact line L2 along the second optical path of displacement to form the second pane of adjacent oblong gas bubbles.

[0179] For the realization of the third panel (i.e. the panel furthest from the horizontal cutting plane Hl), the control unit 60 is configured to drive the optical focusing system 50 in order to position the focal plane of the cutting device at the predefined distance from the second panel so that an end portion of the impact line L3 is in contact with the oblong gas bubbles of the second panel.

[0180] This ensures that the tissue bridges between the different stacked panels are narrow enough to ensure dissection by the practitioner of acceptable quality over the entire height of each vertical cutting plane.

[0181] 2.5.3. Formation of stacked horizontal and vertical cutting planes to create cubes of fabric

[0182] We will now describe in more detail the operating principle of the cutting device with reference to the destruction of a lens in the context of a cataract operation.

[0183] To partition the lens into cubes that can be aspirated by an aspiration cannula, horizontal and vertical cutting planes are formed by starting with the horizontal cutting plane deepest in the lens and stacking successive vertical and horizontal cutting planes up to the plane of the most superficial horizontal cut in the lens.

[0184] With reference to Figures 14 and 15, the deepest horizontal cutting plane H1 is produced in a first step (E310, F310). The control unit 60: • applies a multi-point phase mask to the shaping system 30 to produce a multi-point modulated laser beam, • controls the movement of the focusing system 50 to align the focal plane of the cutting device with the desired deepest cutting plane, • drives the movement of the optical scanning device to a target position along the first optical path (e.g., in a zigzag pattern), and • activates the femtosecond laser source 10 (after stabilization of the scanner's movement speed and reaching the target position).

[0185] A series of shots is performed in the focal plane of the cutting device. With each shot, several impact points simultaneously focus in the focal plane. Each impact point forms a gas bubble. The optical scanner allows the multiple impact points to be moved in the focal plane between each shot. When the entire surface of the horizontal cutting plane is covered with gas bubbles, the horizontal cutting plane H1 is complete.

[0186] In a second step (E320 and F320), a first set of adjacent vertical cutting planes VI is produced with the cutting device. For each vertical cutting plane VI, the control unit 60: • applies a conical phase mask to the shaping system 30 to produce a modulated Bessel laser beam, • controls the movement of the focusing system 50 to position the impact line in the cutting plane (the focusing plane being above or below the cutting plane depending on whether the axicon emulated on the shaping system is a positive or negative axicon), • drives the movement of the optical scanning scanner to a target position along the second optical path (e.g., a segment), and • activates the femtosecond laser source 10 (after stabilization of the scanner's movement speed and reaching the target position).

[0187] A series of shots is performed. With each shot, an impact line is generated. Each impact line forms an oblong gas bubble along the optical axis of propagation of the modulated laser beam. The scanning optical scanner 40 allows the impact line to be moved above / below the focal plane between each shot. When the entire second path of movement is covered with gas bubbles, the vertical cutting plane V1 is complete.

[0188] If the depth of the impact line is less than the desired depth for the vertical cutting plane, then the control unit 60 can control the scanning optical scanner 40 and the focusing optical system 50 to move the impact line along the second optical path by varying the depth of the focal plane of the cutting device between the forward and return movements.

[0189] This yields several vertical cutting planes VI above the initial horizontal cutting plane H1. These cutting planes VI are divided into 2 subgroups (a first subgroup of planes 107' and a second subgroup of planes 107” in [Fig.2]) forming parallel planes within the same subgroup but perpendicular for 2 different subgroups, thus allowing the vertical cutting planes to form a grid, each elementary square representing the lateral walls of the cubes thus cut.

[0190] In a third step (E330, F330), an intermediate horizontal plane H2 is created to cap the vertical cutting planes VI. This horizontal cutting plane H2 is created using the same method as that described with reference to the first step. This yields defined crystalline cubes between the horizontal and vertical planes created in the first, second, and third steps.

[0191] In a fourth step (E340, F340), a second set of adjacent vertical cutting planes V2 is produced with the cutting device. This second set of vertical cutting planes V2 is laterally offset relative to the first set of vertical cutting planes VI. To achieve this, the control unit 60 drives the movement of the scanning optical scanner 40 along a third, different path of movement—specifically, one that is laterally offset—relative to the second optical path. Thus, none of the vertical cutting planes V2 of the second set is coplanar with a vertical cutting plane VI of the first set.

[0192] In a fifth step (E350, F350), an upper horizontal plane H3 is created using the same method as that described with reference to the first step. This results in a stack of two layers of crystalline cubes, the crystalline cubes of the second layer being laterally offset relative to the crystalline cubes of the first layer.

[0193] The preceding steps can be repeated to achieve a stack of more than two layers of crystalline cubes, the cubes of one layer being laterally offset from the crystalline cubes located in the layer below on which they rest.

[0194] 3. Conclusions

[0195] The lateral offset of the vertical cutting planes located above a horizontal cutting plane relative to the vertical cutting planes located below said horizontal cutting plane makes it possible to limit the propagation of gas bubbles to the surface of the fabric to be treated.

[0196] As stated previously, in the case of a cut of ocular tissue, such propagation can induce the accumulation of gas above the cutting plane in the lens, see above the lens in the anterior chamber of the eye and obscure the laser beam, thus preventing the cutting in the anterior part of the lens from being carried out.

[0197] Thus, the invention makes it possible to have an efficient three-dimensional cutting tool allowing to make cuts into elementary portions of the same size and of small dimensions.

[0198] The reader will have understood that many modifications can be made to the invention described above without materially departing from the new teachings and advantages described here.

Claims

Claims

1. Apparatus for cutting human or animal tissue, said apparatus including a femtosecond laser source (10) configured to emit a Gaussian laser beam in the form of pulses and a device for processing the Gaussian laser beam, the processing device being arranged downstream of the femtosecond laser source (10), the processing device comprising: • a shaping system (30) positioned on the path of the Gaussian laser beam, for modulating the phase of the wavefront of the Gaussian laser beam, the shaping system (30) comprising a spatial light modulator (SLM) and being configured to produce a modulated laser beam from the Gaussian laser beam, • an optical scanning scanner (40) arranged downstream of the shaping system to move the modulated laser beam, • an optical focusing system (50) downstream of the shaping system (30), for focusing the modulated laser beam in a focal plane of the cutting apparatus and for moving the focal plane of the cutting apparatus into a plurality of positions along an optical axis (A-A') of propagation of the modulated laser beam, characterized in that the processing device further comprises a control unit (60) for controlling the femtosecond laser source (10), the shaping system (30), the optical scanning scanner (40), and the optical focusing system (50) in order to produce successive horizontal and vertical cutting planes, the horizontal cutting planes extending perpendicular to the optical axis (A-A') and the vertical cutting planes extending parallel to the optical axis (A-A'), said control unit (60) being configured to: • order (E310) the creation of a first horizontal cutting plan (Hl), • command (E320) the creation of a first plurality of vertical cutting planes (VI) above the first horizontal cutting plane (Hl), • command (E330) the creation of a second horizontal cutting plane (H2) above the first plurality of vertical cutting planes (VI), the first horizontal cutting plane (H1) being deeper in the fabric than the second horizontal cutting plane (H2), • command (E340) the creation of a second plurality of vertical planes (V2) above the second horizontal plane (H2), in which the second plurality of vertical cutting planes (V2) is laterally offset relative to the first plurality of vertical planes (VI).

2. The cutting apparatus of claim 1, wherein the second plurality of vertical cutting planes is laterally offset from the first plurality of vertical cutting planes by a distance of between 5 pm and 500 pm.

3. A cutting apparatus according to any one of claims 1 or 2, wherein the second plurality of vertical cutting planes is laterally offset from the first plurality of vertical cutting planes along first and second axes perpendicular to the optical axis (A-A'), the first and second axes being orthogonal to each other.

4. Cutting apparatus according to any one of claims 1 to 3, wherein for the production of each horizontal cutting plane, the control unit (60) is configured to: • apply (E120) a multi-point phase mask to the shaping system (30) to produce a single multi-point modulated laser beam, the multi-point phase mask being calculated to distribute the energy of the multi-point modulated laser beam into at least two impact points in the focal plane of the cutting apparatus, • control (E110) the movement of the focusing system (50) to make the focal plane of the cutting apparatus coincide with the desired depth for the horizontal cutting plane, • control (E140) the optical scanning scanner to move the impact points of the single multi-point modulated laser beam along a first movement path, • activate (E130) the femtosecond laser source (10).

5.

6.

7. Cutting apparatus according to any one of claims 1 to 4, wherein for the production of each vertical cutting plane (VI) of the first plurality, the control unit (60) is configured to: • applying (E220) to the shaping system (30), an axiconic modulation instruction in order to produce a Bessel-type modulated laser beam from the Gaussian laser beam, said modulation instruction comprising a phase mask (314, 315) emulating an axicon applied to the spatial light modulator (SLM), said Bessel-type modulated laser beam creating an impact line making it possible to generate an oblong gas bubble in the tissue, • drive (E240) the optical scanning scanner to move the impact line of the modulated Bessel-type laser beam along a second optical displacement path to form a set of adjacent oblong gas bubbles. Cutting apparatus according to claim 5, wherein for the production of each vertical cutting plane (V2) of the second plurality, the control unit (60) is configured to: • apply (E220) to the shaping system (30) the axiconic modulation instruction, • drive (E240) the optical scanning scanner to move the impact line of the modulated Bessel-type laser beam along a third optical path laterally offset relative to the second optical path. Cutting apparatus according to one of claims 5 or 6, in which each vertical cutting plane is composed of a stack of several sets of adjacent oblong gas bubbles, the control unit (60) being configured to: • control the optical focusing system (50) in order to position the focal plane of the cutting device at a predefined non-zero distance from the first horizontal cutting plane, said predefined distance being less than the length of the impact line of the modulated Bessel-type laser beam of so that the impact line partially intersects the first horizontal cutting plane, • driving the optical scanning scanner to move the impact line of the modulated Bessel-type laser beam to form a first set of adjacent oblong gas bubbles, • driving the focusing optical system (50) to position the focal plane of the cutting apparatus at the predefined distance from the first set of adjacent oblong gas bubbles so that the impact line partially intersects the first set of adjacent oblong gas bubbles, • driving the optical scanning scanner to move the impact line of the modulated Bessel-type laser beam to form a second set of adjacent oblong gas bubbles.

8. A cutting apparatus according to claim 7, wherein the predefined distance is within a V5 and V3 of the length of the impact line.

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