System for cutting ocular tissue into base parts

Abstract

The invention relates to a cutting device comprising a femtosecond laser source for emitting a Gaussian laser beam, a shaping system comprising a spatial light modulator for modulating the Gaussian laser beam, an optical scanner for moving the modulated laser beam, an optical focusing system for focusing the modulated laser beam, characterized in that: the optical scanner is configured to scan the modulated laser beam; the treatment device further comprises a control unit for controlling the femtosecond laser source, the shaping system, the optical scanner and the optical focusing system to create a first and a second set of vertical cutting planes (V1, V2) separated from one another by a horizontal cutting plane (H2), the second set of vertical planes (V2) being laterally offset with respect to the first set of vertical planes (V1).

Description

Technical Field

[0001] The present invention relates to the technical field of surgical operations using femtosecond lasers, and more particularly to the field of ophthalmic surgery, and in particular to applications for cutting corneas or lenses.

[0002] The present invention relates to a device for cutting human or animal tissue (such as the cornea or lens) by means of a femtosecond laser source.

[0003] A “femtosecond laser source” refers to a light source capable of emitting a laser beam in the form of ultrashort pulses, with a duration between 1 femtosecond and 100 picoseconds, preferably between 1 and 1000 femtoseconds, and typically on the order of hundreds of femtoseconds. Background Art

[0004] In certain surgeries (eg, cataract surgery), it is necessary to segment tissue such as the lens C into small particles such as cubes 108 for extraction, such as through the area of ​​the suction cannula CA. Figure 1 shown.

[0005] In order to divide the lens into cubes 108 that can be sucked by the suction cannula, horizontal cutting planes 104a, 104b and vertical cutting plane 107 can be formed, such as Figure 2 These plan views are formed by successively stacking vertical cutting planes 107 and horizontal cutting planes 104b starting from the deepest horizontal cutting plane 104a in the lens, up to the superficial horizontal cutting plane in the lens.

[0006] Document WO 2022 / 090408 specifically describes a cutting device capable of creating horizontal and vertical cutting planes. The cutting device comprises:

[0007] - a femtosecond laser source for emitting a Gaussian laser beam in pulsed form,

[0008] a shaping system, located downstream of the laser source, for modulating the phase of the wavefront of the Gaussian laser beam, the shaping system comprising a spatial light modulator (SLM) and configured to generate a modulated laser beam from the Gaussian laser beam,

[0009] - a sweeping optical scanner, which is arranged downstream of the shaping system to move the modulated laser beam,

[0010] an optical focusing system, downstream of the sweeping optical scanner, for focusing the modulated laser beam in a focal plane of the cutting device and for moving the focal plane to a plurality of positions along the propagation optical axis of the modulated laser beam,

[0011] - A control unit configured to drive the femtosecond laser source, the shaping system, the sweeping optical scanner, and the optical focusing system to create continuous horizontal and vertical cutting planes.

[0012] Reference Figure 3 ,The working principle of this cutting device is as follows.

[0013] In the first step, an initial horizontal cutting plane 104a (ie the deepest layer) is created. Control unit:

[0014] - applying a multi-point phase mask to the shaping system to generate a multi-point modulated laser beam capable of producing multiple impact points simultaneously,

[0015] - controlling the movement of the focusing system so that the focal plane of the cutting device coincides with the desired initial cutting plane,

[0016] - Start the femtosecond laser source, and

[0017] - driving the sweeping optical scanner along a (eg saw-toothed) optical path.

[0018] A series of shots are performed in the focal plane of the cutting device. During each shot, multiple impact points—arranged in a pattern—are simultaneously focused on the focal plane. Each impact point forms a bubble. An optical scanner enables the multi-point modulated laser beam to be moved within the focal plane between shots, thereby shifting the pattern. When the entire surface of the horizontal cutting plane is covered by the bubble, the initial horizontal cutting plane 104a is complete.

[0019] In the second step, a plurality of adjacent vertical cutting planes 107a are created. For each vertical cutting plane, the control unit:

[0020] - applying a conical phase mask (i.e. capable of applying a linear phase modulation with rotational symmetry) to the shaping system to generate a Bessel-type modulated laser beam,

[0021] - controlling the movement of the focusing system to focus the modulated laser beam to the desired depth,

[0022] - Start the femtosecond laser source, and

[0023] - driving the sweeping optical scanner to move along (eg a section of) the optical path.

[0024] A series of shots are performed. With each shot, a line of action is formed. Each line of action generates an elliptical bubble along the optical axis of the modulated laser beam. The optical scanner allows the modulated laser beam, and thus the line of action, to be moved between shots. If the depth of the line of action is less than the desired depth of the vertical cutting plane, the control unit 60 can adjust the optical focusing system 50 to change the depth of the cutting device's focal plane.

[0025] When the entire moving path is covered by the elliptical bubble, the vertical cutting plane 107a is completed.

[0026] The steps of creating horizontal planes 104 b , 104 c , 104 d and vertical planes 107 b , 107 c are repeated to create a stack of lens cubes 108 .

[0027] When a large number of bubbles are formed in different horizontal and vertical planes, the lens cube thus formed can be separated from the uncut portion of tissue by using a tool to separate the existing tissue bridges between the bubbles.

[0028] However, if Figure 4 As shown, the formation of the stack of cubes 108 results in gas accumulation in the upper portion of the planar stack. More specifically, as the stack of cubes 108 is formed, bubbles 109 formed deep within the tissue 2 move toward the most superficial region of the tissue.

[0029] This gas accumulation can extend beyond the laser cutting plane and into the tissue, for example, into the anterior chamber of the eye when cutting the lens. This can cause problems with the laser beam penetrating the tissue. In effect, the gas bubbles form an opaque barrier that prevents the energy generated by the laser beam from propagating below the bubbles, making it impossible to cut the tissue in the area below the gas accumulation.

[0030] This gas accumulation may also cause tissue deformation during cutting, which may result in defects in cube size, making it difficult to aspirate through the cannula.

[0031] One object of the present invention is to propose a device for cutting human or animal tissue that prevents the formation of gas accumulations that could hinder the propagation of the laser beam energy below said accumulations.

[0032] More specifically, an object of the present invention is to propose a cutting device capable of completely cutting tissue, in particular ocular tissue such as the cornea or the lens, while avoiding shielding of the laser beam during the cutting process.

[0033] Another object of the present invention is to provide a device for cutting human or animal tissue that is capable of forming tissue cubes of more uniform size. Summary of the Invention

[0034] To this end, the present invention provides a device for cutting human or animal tissue, the device comprising a femtosecond laser source configured to emit a Gaussian laser beam in a pulsed form and a device for processing the Gaussian laser beam, the processing device being arranged downstream of the femtosecond laser source, the processing device comprising:

[0035] a shaping system located on the trajectory 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 configured to generate a modulated laser beam from the Gaussian laser beam,

[0036] - a sweeping optical scanner, which is arranged downstream of the shaping system to move the modulated laser beam,

[0037] an optical focusing system, downstream of the shaping system, for focusing the modulated laser beam on a focal plane of a cutting device and for moving the focal plane of the cutting device to a plurality of positions along the optical axis of propagation of the modulated laser beam,

[0038] Characterized in that the processing device further includes a control unit for driving the femtosecond laser source, the shaping system, the sweeping optical scanner, and the optical focusing system to create continuous horizontal cutting planes and vertical cutting planes, wherein the horizontal cutting plane extends perpendicular to the optical axis and the vertical cutting plane extends parallel to the optical axis, and the control unit is configured to:

[0039] -Controls the creation of the first horizontal cutting plane,

[0040] - controlling the creation of a first plurality of vertical cutting planes above the first horizontal cutting plane,

[0041] - controlling the creation of a second horizontal cutting plane above the first plurality of vertical cutting planes, the first horizontal cutting plane being positioned deeper in the tissue than the second horizontal cutting plane,

[0042] - controlling creation of a second plurality of vertical planes above the second horizontal plane, wherein the second plurality of vertical cutting planes are laterally offset (in at least one direction perpendicular to the optical axis) relative to the first plurality of vertical planes.

[0043] Within the framework of the present invention, a “horizontal cutting plane” is understood to mean a plane which lies in the tissue to be treated and extends perpendicularly to the propagation optical axis of the laser beam originating from the cutting device.

[0044] Within the framework of the present invention, a “vertical cutting plane” is understood to mean a plane which lies in the tissue to be treated and extends parallel to the optical axis of propagation of the laser beam originating from the cutting device.

[0045] Within the framework of the present invention, a “point of action” is understood to be a point region of the laser beam comprised in the focal plane of the cutting device, wherein the intensity of the laser beam is sufficient to generate gas bubbles in the tissue.

[0046] Within the framework of the present invention, "line of action" refers to a linear region of the laser beam extending perpendicular to the focal plane of the cutting device (i.e. a section of the laser beam extending parallel to the optical axis), wherein the intensity of the laser beam is sufficient to generate elliptical bubbles in the tissue.

[0047] Within the framework of the present invention, “adjacent action points” are understood to mean two action points which are arranged opposite one another and are not separated by another action point.

[0048] "Neighboring action points" refer to the two points with the smallest distance between them in a group of adjacent points.

[0049] Within the framework of the present invention, a "pattern" is understood to mean a plurality of laser impact points generated simultaneously.

[0050] Thus, the present invention is able to generate multiple sets of vertical cutting planes separated by horizontal cutting planes to form a basic cube of tissue that can be aspirated by the suction cannula.Advantageously, each set of vertical cutting planes is laterally offset relative to its adjacent set of vertical cutting planes.

[0051] Specifically, each group is defined by a plurality of vertical cutting planes formed between two horizontal cutting planes. In the case where three superimposed horizontal cutting planes are provided in the tissue, namely:

[0052] - Deep horizontal cutting planes,

[0053] - a middle horizontal cutting plane, and

[0054] - shallow horizontal cutting plane,

[0055] Then two sets of vertical cutting planes are formed between the horizontal cutting planes:

[0056] - forming a first set of vertical cutting planes between the deep horizontal cutting plane and the intermediate horizontal cutting plane, and

[0057] A second set of vertical planes is formed between the intermediate cutting plane and the shallow cutting plane, the second set of vertical cutting planes being laterally offset relative to the first set of vertical cutting planes.

[0058] Such lateral offsets between adjacent groups of vertical cutting planes can prevent gas contained in bubbles formed in one group of vertical cutting planes from propagating toward bubbles formed in a more shallow adjacent group of vertical cutting planes, as will be apparent from the following description.

[0059] Optical phase modulation is performed using a phase mask. The energy of the incident laser beam remains unchanged after modulation, and beam shaping is achieved by acting on its wavefront. The phase of an electromagnetic wave represents the instantaneous amplitude of the wave. Phase depends on both time and space. In the case of spatial shaping of a laser beam, only the spatial variation of the phase is considered.

[0060] The wavefront is defined as the surface formed by points on a beam of light with equivalent phase (i.e., the surface consisting of points with equal travel times from the source emitting the beam). Therefore, a change in the spatial phase of a beam involves a change in its wavefront.

[0061] Within the framework of the present invention, the phase modulation of the wavefront enables the generation of a single modulated laser beam, which forms:

[0062] - multiple action points only within the cutting plane (for forming a horizontal cutting plane); in this case, the modulated laser beam is unique over the entire propagation path, and the phase modulation of the wavefront enables the phase of different points on the beam surface to be delayed or advanced relative to the initial wavefront, so that each of these points produces constructive interference at N different points in the focal plane of the lens, and the energy redistribution to the multiple action points occurs only in a single plane (i.e., the focal plane), rather than in the entire propagation path of the modulated laser beam,

[0063] - or perpendicular to the line of action of the focal plane of the cutting device (for forming a vertical cutting plane).

[0064] Preferred but non-limiting aspects of the cutting device are as follows:

[0065] - the second plurality of vertical cutting planes may be laterally offset relative to the first plurality of vertical cutting planes by a distance between 5 μm and 500 μm;

[0066] - the second plurality of vertical cutting planes may be laterally offset relative to the first plurality of vertical cutting planes along a first axis and a second axis perpendicular to the optical axis, the first axis and the second axis being orthogonal to each other;

[0067] - To create each horizontal cutting plane, the control unit can be configured to:

[0068] o applying a multi-point phase mask to the shaping system to generate a single multi-point modulated laser beam, calculating the multi-point phase mask to distribute the energy of the multi-point modulated laser beam to at least two impact points in the focal plane of the cutting device,

[0069] o controlling the movement of the focusing system so that the focal plane of the cutting device coincides with the desired depth of the horizontal cutting plane,

[0070] o driving the scanning optical scanner to move the action point of the single beam multi-point modulated laser beam along a first movement path,

[0071] oStart the femtosecond laser source;

[0072] - For creating each of the first plurality of vertical cutting planes, the control unit may be configured to:

[0073] o applying an axicon modulation setpoint to a shaping system to generate a Bessel-type modulated laser beam from a Gaussian laser beam, the modulation setpoint comprising a phase mask simulating an axicon applied to a spatial light modulator, the Bessel-type modulated laser beam generating a line of action capable of generating an elliptical bubble in tissue,

[0074] o driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam along a second optical movement path to form a group of adjacent elliptical bubbles;

[0075] - For creating each of the second plurality of vertical cutting planes, the control unit is configured to:

[0076] oApply the axicon modulation set point to the shaping system,

[0077] o driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam along a third optical path that is laterally offset relative to the second optical path;

[0078] - Each vertical cutting plane is composed of a stack of multiple groups of adjacent elliptical bubbles, and the control unit (60) is configured as follows:

[0079] o driving the optical focusing system so as to position the focal plane of the cutting device at a predetermined non-zero distance from the first horizontal cutting plane, said predetermined distance being less than the length of the line of action of the Bessel-type modulated laser beam, such that the line of action partially intersects the first horizontal cutting plane,

[0080] o driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam to form a first group of adjacent elliptical bubbles,

[0081] o driving the optical focusing system so as to position the focal plane of the cutting device at a predetermined distance from the first group of adjacent elliptical bubbles so that the line of action partially intersects the first group of adjacent elliptical bubbles,

[0082] o driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam to form a second group of adjacent elliptical bubbles;

[0083] - The predetermined distance may be between 1 / 5 and 1 / 3 of the length of the line of action.

[0084] The present invention also relates to a method for cutting tissue, such as previously collected human or animal tissue, by means of a cutting device comprising:

[0085] - a femtosecond laser source configured to emit a Gaussian laser beam in a pulsed form,

[0086] a shaping system downstream of the femtosecond laser source and located on the trajectory 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 configured to generate a modulated laser beam from the Gaussian laser beam,

[0087] - a sweeping optical scanner, which is arranged downstream of the shaping system to move the modulated laser beam,

[0088] an optical focusing system, downstream of the shaping system, for focusing the modulated laser beam on a focal plane of a cutting device and for moving the focal plane of the cutting device to a plurality of positions along the optical axis of propagation of the modulated laser beam,

[0089] The cutting method includes a stage of creating continuous horizontal cutting planes and vertical cutting planes by driving a femtosecond laser source, a shaping system, a sweeping optical scanner, and an optical focusing system, wherein the horizontal cutting plane extends perpendicular to the optical axis and the vertical cutting plane extends parallel to the optical axis, and the creation stage includes the following steps:

[0090] - forming a first horizontal cutting plane,

[0091] - forming a first plurality of vertical cutting planes above the first horizontal cutting plane,

[0092] - forming a second horizontal cutting plane above the first plurality of vertical cutting planes, the first horizontal cutting plane being located deeper in the tissue than the second horizontal cutting plane,

[0093] A second plurality of vertical planes is formed above the second horizontal plane and is laterally offset relative to the first plurality of vertical planes.

[0094] Preferred but non-limiting aspects of the method according to the invention are as follows:

[0095] - the second plurality of vertical cutting planes may be laterally offset relative to the first plurality of vertical cutting planes by a distance between 5 μm and 500 μm;

[0096] - the second plurality of vertical cutting planes may be laterally offset relative to the first plurality of vertical cutting planes along a first axis and a second axis perpendicular to the optical axis, the first axis and the second axis being orthogonal to each other;

[0097] Each step of forming a horizontal cutting plane may include the following sub-steps:

[0098] o applying a multi-point phase mask to the shaping system to generate a single multi-point modulated laser beam, calculating the multi-point phase mask to distribute the energy of the multi-point modulated laser beam to at least two points in the focal plane of the cutting device,

[0099] o Using a focusing system to move the focal plane of the cutting device to the desired depth of the horizontal cutting plane,

[0100] o moving the point of impact of the single multi-spot modulated laser beam along a first movement path using a sweeping optical scanner, and

[0101] oEmitting a Gaussian laser beam through a femtosecond laser source;

[0102] Each step of forming a first plurality of vertical cutting planes may comprise the following sub-steps:

[0103] o applying an axicon modulation setpoint to a shaping system so as to generate a Bessel-type modulated laser beam, the modulation setpoint comprising a phase mask simulating an axicon applied to a spatial light modulator, the phase mask having rotational symmetry about a center point of symmetry, the grayscale of each point of the phase mask varying according to the distance between the point and the center point of symmetry, the Bessel-type modulated laser beam generating a line of action capable of generating an elliptical bubble in tissue,

[0104] o moving the line of action of the Bessel-type modulated laser beam along a second optical movement path using a sweeping optical scanner to form a set of adjacent elliptical bubbles;

[0105] Each step of forming a second plurality of vertical cutting planes may comprise the following sub-steps:

[0106] oApply the axicon modulation set point to the shaping system,

[0107] o moving the line of action of the Bessel-type modulated laser beam along a third optical movement path that is laterally offset relative to the second optical path using a sweeping optical scanner;

[0108] Each vertical cutting plane may be composed of a stack of multiple groups of adjacent elliptical bubbles, and each step of forming a vertical cutting plane includes the following sub-steps:

[0109] o moving the focal plane of the cutting device to a predetermined non-zero distance from the first horizontal cutting plane using an optical focusing system, the predetermined distance being less than the length of the line of action of the Bessel-type modulated laser beam, such that the line of action partially intersects the first horizontal cutting plane,

[0110] o moving the line of action of the Bessel-type modulated laser beam using a sweeping optical scanner to form a first set of adjacent elliptical bubbles,

[0111] o moving the focal plane of the cutting device to a predetermined distance from the first group of adjacent elliptical bubbles using an optical focusing system so that the line of action partially intersects the first group of adjacent elliptical bubbles,

[0112] o moving the line of action of the Bessel-type modulated laser beam using a sweeping optical scanner to form a second set of adjacent elliptical bubbles;

[0113] - The predetermined distance may be between 1 / 5 and 1 / 3 of the length of the line of action. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Other characteristics and advantages of the invention will emerge clearly from the following description given by way of information and not limitation, with reference to the accompanying drawings, in which:

[0115] - Figure 1 is a schematic diagram of the patient's eye.

[0116] - Figure 2 It is a schematic diagram of bubbles generated when forming a basic tissue cube through horizontal cutting planes and vertical cutting planes.

[0117] - Figure 3 is a schematic diagram of a stack of horizontal and vertical cutting planes obtained using the cutting device described in document WO 2016 / 055539,

[0118] - Figure 4 is a schematic diagram showing gas accumulation after forming superimposed vertical cutting planes using the cutting device described in document WO 2016 / 055539,

[0119] - Figure 5 is a schematic diagram of a cutting device according to the present invention,

[0120] - Figure 6 is a schematic diagram showing the focusing of a Bessel-type non-diffracting beam,

[0121] - Figure 7a is an image of a first phase mask of the SLM of the cutting device according to the present invention capable of simulating the behavior of a negative axicon,

[0122] - Figure 7b is an image of a second phase mask of the SLM of the cutting device according to the present invention capable of simulating the behavior of an axicon,

[0123] - Figure 8 This is a partial installation diagram of the cutting device.

[0124] - Figure 9 is a schematic diagram of a Bessel beam,

[0125] - Figure 10 is a schematic diagram of the control steps during the creation of the horizontal cutting plane,

[0126] - Figure 11 is a schematic diagram of the control steps during the creation of the vertical cutting plane,

[0127] - Figure 12 is a schematic diagram showing the formation of a vertical cutting plane by a Bessel laser beam,

[0128] - Figure 13 is a schematic diagram showing a set of lines of action for creating stacked elliptical bubble sections,

[0129] - Figure 14 is a schematic diagram of the control steps during the creation of successive horizontal and vertical cutting planes,

[0130] - Figure 15 It is a schematic diagram of the horizontal and vertical cutting planes that are created successively. DETAILED DESCRIPTION

[0131] The present invention relates to a system for cutting human tissue by means of a femtosecond laser.In the remainder of this specification, the present invention will be described by way of example for cutting a lens of a human or animal eye.

[0132] 1. Cutting device

[0133] Reference Figure 5 , shows an embodiment of a cutting device according to the present invention. The device can be arranged between a femtosecond laser source 10 and a target 2 to be processed.

[0134] The femtosecond laser source 10 can emit 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.

[0135] The target 2 is, for example, human or animal tissue to be cut, such as a cornea or a lens.

[0136] The cutting device includes:

[0137] a shaping system 30 located on the trajectory of the laser beam 110 originating from the femtosecond laser 10 ,

[0138] - a sweeping optical scanner 40 , downstream of the shaping system 30 ,

[0139] - an optical focusing system 50 downstream of the sweeping optical scanner 40, and

[0140] - Control unit 60.

[0141] The shaping system 30 is capable of modulating the phase of the laser beam 110 originating from the femtosecond laser source 10. The shaping system 30 is advantageously a programmable component.

[0142] The sweeping optical scanner 40 is capable of directing the phase modulated laser beam 310 originating from the shaping system 30 to move the cutting pattern along a user predefined movement path in the focal plane 101 of the cutting system.

[0143] The optical focusing system 50 is capable of moving the focal plane 101 (corresponding to the cutting plane) of the modulated and deflected laser beam 410 .

[0144] The control unit 60 is capable of driving the shaping system 30 , the sweeping optical scanner 40 and the optical focusing system 50 .

[0145] The cutting device is suitable for forming a horizontal cutting plane and a vertical cutting plane. Depending on the type of cutting plane required (vertical or horizontal), the control unit 60:

[0146] - configuring the shaping system to modulate the laser beam 110 according to the desired appearance of the point / line of action, and

[0147] - Adjusting the sweeping optical scanner 40 and the optical focusing system 50 to produce the desired cutting plane.

[0148] As will be described in more detail below, the inventors have developed an original solution for configuring a cutting device to form a vertical cutting plane.

[0149] 2. Cutting device components

[0150] 2.1. Plastic surgery system

[0151] The laser beam spatial shaping system 30 is capable of changing the wavefront of the laser beam 110 according to the desired shape:

[0152] - in the case of forming a horizontal cutting plane, for the point of impact of the modulated laser beam, or

[0153] - In the case of forming a vertical cutting plane, the line of action for the modulated laser beam.

[0154] The shaping system 30 preferably comprises a spatial light modulator, known as an SLM.

[0155] The SLM is capable of modulating the final energy distribution of the laser beam 110 originating from the laser source 10. The SLM is a device composed of a liquid crystal layer with controllable orientation, which can dynamically shape the wavefront, thereby changing the phase of the laser beam 110. The liquid crystal layer of the SLM is organized into a grid (or matrix) of pixels. The optical thickness of each pixel is electrically controlled by the orientation of the liquid crystal molecules (which belong to the surface corresponding to the pixel). The SLM uses the principle of liquid crystal anisotropy, that is, the refractive index of the liquid crystal is changed according to the spatial orientation of the liquid crystal. The liquid crystal can be oriented using an electric field. Therefore, the change in the refractive index of the liquid crystal causes the wavefront of the laser beam to change.

[0156] In a known manner, the SLM implements a phase mask, that is to say a map that determines how the phase of the laser beam 110 must be varied in order to obtain a given amplitude distribution. A phase mask is a two-dimensional image, each point of which is associated with a corresponding pixel of the SLM. Such a phase mask is capable of driving the refractive index of each liquid crystal of the SLM by converting the values ​​associated with each point of the mask (expressed in grayscale between 0 and 255, therefore from black to white) into control values ​​(expressed in phase between 0 and 2π). The phase mask is therefore a modulation set point displayed on the SLM to induce, upon reflection, an inhomogeneous spatial phase shift of the laser beam 110 irradiating the SLM. Of course, a person skilled in the art will understand that the grayscale range may vary depending on the SLM model used. For example, in some cases the grayscale range may be between 0 and 220.

[0157] Depending on the type of cutting plane the user wishes to create, different phase masks can be applied to the SLM, namely:

[0158] - vertical cutting plane,

[0159] - or horizontal cutting plane.

[0160] In order to create the vertical cutting plane, the phase mask used (hereinafter referred to as "conical phase mask") is capable of applying a linear phase modulation with rotational symmetry, thereby obtaining a Bessel-type modulated laser beam.

[0161] To create a horizontal cutting plane, the phase mask used (hereinafter referred to as a "multi-point phase mask") is capable of applying phase modulation to distribute the laser beam energy to at least two points forming a pattern in the focal plane of the cutting system. Thus, a multi-point modulated laser beam is obtained.

[0162] 2.1.1. Vertical cutting plane

[0163] Regarding the cutting of vertical surfaces, the inventors propose to modulate the phase of the laser beam 110 originating from the femtosecond laser source 10 in order to generate a Bessel-type modulated laser beam 310 downstream of the shaping system 30 .

[0164] A Bessel beam is called a "diffraction-free" beam because it has the property of maintaining a constant intensity distribution along the optical axis of laser beam propagation (hereinafter referred to as the "optical axis"), which is different from the behavior of a Gaussian laser beam (such as the laser beam 110 originating from the femtosecond laser source 10) which diverges when focused.

[0165] 2.1.1.1. Bessel beam

[0166] An ideal zero-order Bessel beam can be mathematically defined as a beam whose electric field € is formally described by the zero-order Bessel function of the first kind J0:

[0167] E(r,Φ,z)A0J0(k r r)e jk z z

[0168] in:

[0169] -A0 is the amplitude of the electric field,

[0170] -K z and k r are the longitudinal and radial wave vectors,

[0171] -z, r and Φ are the longitudinal, radial and azimuthal components.

[0172] Reference Figure 6 , the formation of the Bessel beam 313 is caused by the interference of plane waves whose wave vectors form a conical surface.

[0173] Theoretically, the lateral extension of the ring structure is infinite, and the diffraction-free propagation distance is also infinite.

[0174] In practice, due to the finite propagation and finite energy observed in optics, the experimentally obtained Bessel beam has a finite undiffraction propagation distance Z along the optical axis B This limited non-diffraction propagation distance Z B A non-diffraction zone ZND is defined.

[0175] Assumption Z B >>Z R , Z R is the Rayleigh distance of an ordinary Gaussian beam of similar lateral dimensions. In other words, the depth of each impact point of a Bessel beam (i.e., the dimension along a direction parallel to the optical axis of the laser beam propagation) is much greater than the depth of each impact point of a Gaussian laser beam (e.g., a laser beam originating from a femtosecond laser source).

[0176] Therefore, Bessel beams can be used to ablate tissue to a much greater depth than Gaussian beams. Specifically, a single line of action of a Bessel beam can ablate tissue to a depth equivalent to the depth of the four combined points of action of a Gaussian beam. Using a swept optical scanner, the line of action of a Bessel beam can be moved to produce a perfectly vertical ablation plane at four times the speed of the points of action of a Gaussian beam.

[0177] Due to the unique formation of the Bessel beam based on a conical wavefront, it has a significant self-reconstruction property. This means that the beam can reconstruct itself even if it encounters any obstacles along its path within the non-diffraction zone ZND. Even when a portion of the modulated laser beam 310 is blocked by an obstacle, this property ensures that the cutting quality of the vertical surface is guaranteed by ensuring that an extended bubble is formed with each shot of the laser source 10.

[0178] 2.1.1.2. Conical phase mask for forming a Bessel-type modulated laser beam

[0179] There are various techniques for generating Bessel beams from Gaussian laser beams. These techniques usually involve axicon phase modulation.

[0180] Specifically, Bessel beams can be obtained by using a conical lens called an "axicon." A conical lens can be concave / hollow (called a "negative axicon") or convex / convex (called a "positive axicon").

[0181] The inventors propose using a shaping system 30 including an SLM to generate a Bessel beam, eliminating the need for optical / mechanical components. To this end, a control unit 60 applies a conical phase mask (which can simulate an axicon) to the SLM. The SLM then performs conical phase modulation on the Gaussian laser beam 110 originating from the femtosecond laser source 10. Thus, using the same SLM, without changing optical components, it is possible to create horizontal cutting planes in multi-spot mode and then vertical cutting planes in Bessel beam mode. This significantly reduces the surgical time to between 30 seconds and 1 minute, meeting the application requirement of completing the procedure on the patient's eye within 3 minutes.

[0182] The SLM to be applied to the shaping system to form a conical phase mask for the Bessel-type modulated laser beam can be calculated:

[0183] - by using the partitioning algorithm (Vellekoop and Mosk, 2008),

[0184] - or any other algorithm known to those skilled in the art.

[0185] Figure 7a and Figure 7bWhen one of the first and second phase masks is applied to the SLM, the SLM can superimpose the phase distribution of the axicon on the input Gaussian laser beam 110 to obtain a Bessel-type modulated laser beam 310 at the output of the shaping system 30.

[0186] Reference Figure 7a , the first conical phase mask (reference numeral 314) can simulate the behavior of a negative axicon (ie, a concave axicon). Figure 7b The second conical phase mask (reference numeral 315) can simulate the behavior of a positive axicon (i.e., a convex axicon). These first and second phase masks each have rotational symmetry around a center point of symmetry, and the grayscale of each pixel varies with the distance between the pixel and the center point of symmetry.

[0187] when Figure 7a and Figure 7b When one of the phase masks shown is applied to the SLM, the shaping system 30 can form the Gaussian laser beam 110 originating from the femtosecond laser source 10 (at the input end of the shaping system 30) into a Bessel-type modulated laser beam 310 (at the output end of the shaping system 30). Thus, a modulated laser beam with a Bessel beam spatial intensity distribution is obtained.

[0188] 2.1.1.3. Mounting of a cutting device as part of tissue cutting by a Bessel-type modulated laser beam

[0189] Figure 8 The schematic diagram of the installation of the cutting device is shown. This schematic diagram is partial because it does not show the femtosecond laser source and the scanning optical scanner. Figure 8 In FIG. 5 , the optical focusing system 50 is represented (as a whole) by an equivalent lens 51 . It should be understood by those skilled in the art that the optical focusing system 50 is not composed of only fixed lenses.

[0190] Reference Figure 8 The Bessel beam 313 is formed after the conical phase modulation surface, that is, after the SLM of the shaping system 30. The SLM simulates a conical lens (negative or positive axicon), and the center point of the maximum intensity of the Bessel beam is formed in the image-side focal plane 32 of the SLM.

[0191] The equivalent lens 51 of the optical focusing system 50 is arranged downstream of the shaping system 30 and arranged so that the object-side focal plane 52 of the equivalent lens extends a non-zero distance from the image-side focal plane 32 of the shaping system 30 along the optical axis.

[0192] Therefore, the object focal plane 52 of the equivalent lens 51 of the optical focusing system 50 extends outside the non-diffraction zone ZND of the Bessel beam, so that the output end of the cutting system is obtained as follows: Figure 9More specifically, a Bessel beam consists of:

[0193] - a Bessel ring 33a, which is focused on the image-side focal plane 53 of the equivalent lens 51 (corresponding to the focal plane of the cutting device),

[0194] A light concentration line 33 b of the Bessel beam (corresponding to the image of the non-diffraction zone ZND), said line 33 b being formed outside the image-side focal plane 53 of the equivalent lens 51 .

[0195] Within the framework of the invention, line 33b constitutes the line of action for creating the vertical cutting plane (the energy contained in the Bezier ring is insufficient to form a bubble).

[0196] Depending on the sign of the phase modulation, line 33b can be formed before or after ring 33a. In other words, the position of line 33b relative to ring 33a depends on the type of axicon (positive or negative) simulated by the conical phase mask.

[0197] Because the Bessel non-diffraction zone ZND (i.e., line 33b) is moved out of the focal plane of the cutting system, the unmodulated light does not interfere. This allows for better control of the intensity distribution without the energy losses associated with beam filtering.

[0198] 2.1.2. Horizontal cutting plane

[0199] Regarding cutting of the horizontal plane, the inventors propose to modulate the phase of the laser beam 110 originating from the femtosecond laser source 10 in order to generate a multi-spot modulated laser beam downstream of the shaping system 30 .

[0200] To this end, a multi-point phase mask is calculated to be applied to the SLM to obtain a multi-point modulated laser beam. The multi-point phase mask is typically calculated as follows:

[0201] - an iterative algorithm based on the Fourier transform, for example an algorithm of the IFTA (Iterative Fourier Transform Algorithm) type, or

[0202] - Various optimization algorithms, such as genetic algorithms or simulated annealing.

[0203] The multi-point phase mask is calculated to form intensity peaks in the focal plane of the cutting device, each intensity peak generating a corresponding impact point in the focal plane of the cutting device.

[0204] More specifically, a multi-point phase mask is calculated to distribute the energy of the laser beam originating from the laser source to multiple points of impact in the focal plane of the cutting device, forming a pattern. This wavefront modulation can be viewed as a two-dimensional interference phenomenon. Each portion of the initial laser beam originating from the light source is delayed or advanced relative to the initial wavefront, causing each of these portions to be redirected to produce constructive interference at N different points in the focal plane of the lens. This redistribution of energy to multiple points of impact occurs only in a single plane (i.e., the focal plane), rather than along the entire propagation path of the modulated laser beam. Therefore, the resulting multi-point laser beam (at the output of the shaping system 30) is unique: because this phenomenon is similar to constructive interference (it occurs only in one plane, rather than throughout the entire propagation process as in the case of the initial laser beam being split into multiple secondary laser beams), observation of the modulated laser beam before or after the focal plane of the cutting device (corresponding to the focal plane of the optical focusing system 50) cannot identify the energy redistribution to multiple different points of impact.

[0205] The use of a single multi-point modulated laser beam facilitates integration with a scanning system (e.g., an optical scanner) to achieve movement of multiple points of action in the focal plane. In fact, the input diameter of the scanning system is approximately the diameter of the initial laser beam originating from the laser source 10. The use of a single multi-point modulated laser beam (whose diameter is substantially equal to the diameter of the initial laser beam) limits the risk of aberrations that may occur with beam splitting techniques such as those described in document US 2010 / 0133246.

[0206] Therefore, the shaping system 30 can distribute the laser beam energy through phase modulation using a multi-point phase mask applied to the SLM, using a Gaussian laser beam that generates a single impact point. This allows the single laser beam shaped by phase modulation (the single beam upstream and downstream of the SLM) to simultaneously generate multiple impact points in the focal plane of the cutting device. This can reduce the time required to create a horizontal cutting plane.

[0207] 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). A person skilled in the art knows how to calculate the value of each point of a multi-point phase mask for distributing the energy of the laser beam to the different impact points in the focal plane of the cutting device.

[0208] 2.2. Scanning optical scanner

[0209] The sweeping optical scanner 40 is capable of deflecting a (Bessel or multi-point) modulated laser beam 310 such that:

[0210] - To create a horizontal cutting plane, move the action point to multiple positions along the first movement path,

[0211] - To create the vertical cutting plane, the line of action is moved to a plurality of positions along the second movement path.

[0212] The scanning optical scanner 40 comprises:

[0213] an input aperture for receiving the phase-modulated laser beam 31 originating from the shaping unit 30,

[0214] - one (or more) optical mirrors pivoting about at least two axes to deflect the phase-modulated laser beam 310, and

[0215] An output aperture for transmitting the deflected modulated laser beam 410 towards the optical focusing system 50 .

[0216] The optical scanner 40 used is, for example, the scanning head IntelliScan III from SCANLAB AG.

[0217] The diameters of the input aperture and the output aperture of the optical scanner 40 are approximately 10 to 20 mm, and the achievable scanning speed is approximately 1 m / s to 10 m / s.

[0218] The reflector is connected to one or more motors to enable it to pivot. The motors for pivoting the reflector are advantageously driven by a control unit 60, which will be described in more detail below.

[0219] The control unit 60 is programmed to drive the sweeping optical scanner 40 so that:

[0220] - moving the point of action along a first movement path,

[0221] - moving the line of action along a second movement path.

[0222] In case of a horizontal cutting plane, the first movement path comprises a plurality of cutting segments.The first movement path may advantageously have a sawtooth shape.

[0223] In the case of a vertical cutting plane, the second movement path includes a segment. The control unit 60 can be configured to command the optical scanner 40 to move the Bezier line of action back and forth along the segment so as to cut the vertical cutting plane across its entire depth. For example, if the optical scanner 40 starts the segment from the left, it will start the segment from the right on its way back, then from the left, then from the right, and so on, until the entire height of the vertical cutting plane is covered.

[0224] The sweep of the beam has an impact on the cutting result obtained. In fact, the sweep speed and the sweep spacing used are parameters that affect the cutting quality.

[0225] Advantageously, the control unit 60 can be programmed to activate the femtosecond laser 10 when the sweep speed of the optical scanner 40 is greater than a threshold value. This enables the emission of the laser beam 110 to be synchronized with the sweep of the optical scanner 40. More specifically, the control unit 60 activates the femtosecond laser 10 when the pivoting speed of the mirror of the optical scanner 40 is constant. This can improve the cutting quality by performing a uniform surface treatment of the cutting plane.

[0226] 2.3. Optical focusing system

[0227] The optical focusing system 50 is able to move the focal plane of the cutting device depending on the type of cutting plane to be created.

[0228] The optical focusing system 50 comprises:

[0229] an input aperture for receiving a phase-modulated and deflected laser beam originating from a sweeping optical scanner 40,

[0230] - one (or more) motorized lenses for enabling translation along the optical path of the modulated and deflected laser beam, and

[0231] - An output aperture for sending the focused laser beam towards the tissue to be treated.

[0232] The control unit 60 is programmed to drive the movement of the lens of the optical focusing system 50 and thereby move the focal plane of the cutting device according to the type of cutting plane to be created.

[0233] In case of a horizontal cutting plane, the cutting plane corresponds to the focal plane of the cutting device.The control unit 60 drives the movement of the lenses of the optical focusing system 50 to focus the modulated and deflected laser beam 410 to a desired depth corresponding to the depth of the cutting plane to be created.

[0234] In the case of a vertical cutting plane, the cutting plane can be located at:

[0235] - in the case where the conical phase mask used enables the SLM to simulate an axicon (Bessel ring 33a is located above the line of action used to perform the cutting), below the focal plane of the cutting device,

[0236] - above the focal plane of the cutting device in case the conical phase mask used enables the SLM to simulate a negative axicon (Bessel ring 33a is located below the line of action used to perform the cutting),

[0237] Preferably, the distance between two consecutive cutting planes is between 2 μm and 500 μm, in particular:

[0238] - between 2 and 20 μm, preferably with a pitch of 5 to 10 μm, when working with volumes requiring high precision (e.g. in refractive surgery); or

[0239] - When processing volumes that do not require high precision (for example when destroying the central part of the lens nucleus), between 20 and 500 μm, preferably with a pitch between 50 and 300 μm.

[0240] Of course, this distance may vary within the volume consisting of the stack of cutting planes.

[0241] 2.4. control unit

[0242] As mentioned above, the control unit 60 is capable of regulating various components of the cutting device, namely, the femtosecond laser source 10 , the shaping system 30 , the sweeping optical scanner 40 and the optical focusing system 50 .

[0243] The control unit 60 is connected to these various components via one (or more) communication buses so that:

[0244] -Control signals can be transmitted, such as:

[0245] The start signal of the femtosecond laser source 10,

[0246] a phase mask of the shaping system 30,

[0247] the scanning speed of the sweeping optical scanner 40,

[0248] the position of the sweep optical scanner 40 along the movement path,

[0249] • Cutting depth of the optical focusing system 50 .

[0250] - Measurement data from various elements of the system can be received, such as:

[0251] The sweep speed achieved by the optical scanner, or

[0252] The location of the optical focusing system, etc.

[0253] The control unit 60 may be composed of one or more workstations and / or one or more computers, or may be of any other type known to those skilled in the art. The control unit 60 may include, for example, a mobile phone, a tablet computer (e.g. ), personal digital assistants (PDAs), etc.

[0254] In all cases, the control unit 60 includes a processor that is programmed to drive the femtosecond laser source 10, the shaping system 30, the sweeping optical scanner 40, the optical focusing system 50, and the like.

[0255] Advantageously, the control unit 60 is programmed to vary the shape of the modulated laser beam between two consecutive cutting planes, in particular between a horizontal cutting plane and a vertical cutting plane.

[0256] 2.5. How it works

[0257] The working principle of the cutting device according to the present invention will now be described in more detail by detailing the following:

[0258] - the operation of creating a horizontal cutting plane,

[0259] - the operation of the device to create a vertical cutting plane,

[0260] - The device creates a superposition of stacked horizontal cutting planes and vertical cutting planes.

[0261] 2.5.1. Formation of horizontal cutting plane

[0262] Within the framework of the present invention, the formation of the horizontal cutting plane is carried out as follows.

[0263] Reference Figure 10 , the control unit 60 sends a control signal to the optical focusing system 50 to drive it to move, so that the focal plane of the cutting device coincides with the desired horizontal cutting plane (step E110).

[0264] The control unit 60 transmits the multi-point phase mask to the shaping system 30 to generate a multi-point modulated laser beam (step E120 ).

[0265] The control unit 60 also starts the movement of the scanning optical scanner 40 to the initial position of the first scanning optical path. Since the scanning is performed in the X and Y directions, the scanner is equipped with one or more reflective mirrors. For example, Figure 5 In the embodiment shown, the sweeping optical scanner 40 comprises a first mirror X and a second mirror Y, the pivoting of which enables the modulated laser beam to move along a first movement path. As a variant embodiment, the scanner can be equipped with a single mirror configured to pivot about two different axes.

[0266] When the following conditions are met:

[0267] - the focusing system 50 and the optical scanner 40 are in position (i.e. the scanner has reached the starting position of the target line),

[0268] - a multi-point phase mask is loaded into the shaping system 30, and

[0269] - the pivoting speed of the mirror of the optical scanner 40 is constant,

[0270] The control unit 60 activates the femtosecond laser source 10 to emit laser pulses (step E130 ).

[0271] The femtosecond laser source 10 generates a laser beam 110 that passes through a shaping system 30. The shaping system 30 modulates the phase of the laser beam to generate a single multi-spot modulated laser beam.

[0272] 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 .

[0273] The modulated and deflected laser beam 410 enters the optical focusing system 50, which focuses the beam into the focal plane of the cutting device. Within the focal plane, the modulation setpoints (i.e., the multi-point phase mask) applied to the shaping system 30 distribute the energy to multiple impact points. These multiple, simultaneously generated impact points form a pattern. Each impact point in the pattern simultaneously generates a bubble.

[0274] 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 pivots by a certain angle, which causes the pattern 8 to move and a new bubble to be generated along the first optical path, offset relative to the previous bubble (step E140 ).

[0275] The operation of driving the femtosecond laser source 10 and scanning the optical scanner 40 is repeated to form a horizontal cutting plane.

[0276] By changing the moving speed of the mirror and / or the rate at which the femtosecond laser source 10 generates pulses, the distance between two consecutive patterns can be changed.

[0277] Once the cutting line has been completed, the control unit 60 deactivates the femtosecond laser source 10 and controls the optical scanner 40 to move to the next cutting position according to the first movement path.

[0278] When the optical scanner 40 is in position and the mirror has reached its constant set point speed, the control unit 60 restarts the femtosecond laser source 10. The laser beam 110 passes through the shaping system 30, the optical scanner 40, and the optical focusing system 50. A new bubble line is formed on the cutting plane, parallel to the previous bubble line.

[0279] When the optical scanner 40 has scanned all positions of the first moving path, the horizontal cutting plane is completed.

[0280] In summary, to create a horizontal cutting plane, the control unit 60 is configured to:

[0281] - applying a multi-point phase mask to the shaping system 30 to generate a single multi-point modulated laser beam, calculating the multi-point phase mask to distribute the energy of the multi-point modulated laser beam to at least two points of action in the focal plane of the cutting device,

[0282] - controlling the movement of the focusing system 50 so that the focal plane of the cutting device coincides with the desired depth of the horizontal cutting plane,

[0283] - driving the scanning optical scanner 40 to move the point of action of the single beam multi-point modulated laser beam along a first movement path, and

[0284] - Start the femtosecond laser source 10 (after the movement speed of the scanner has stabilized).

[0285] 2.5.2. Formation of vertical cutting plane

[0286] Within the framework of the invention, the formation of the vertical cutting plane is carried out as follows.

[0287] Reference Figure 11 , the control unit 60 sends a control signal to the optical focusing system 50 to drive its movement, thereby positioning the focal plane of the cutting device at a given depth relative to the desired position of the vertical cutting plane (step E210). In fact, as mentioned above, in the case of a vertical cutting plane, the cutting plane can be located at:

[0288] if the conical phase mask used enables the SLM to simulate an axicon (the Bessel ring 33a is located above the line of action for performing the cutting), the cutting plane is above the focal plane of the cutting device, in which case the control unit 60 drives the optical focusing system 50 to focus the modulated and deflected laser beam 410 to a desired depth that is less than the maximum depth of the vertical cutting plane to be created,

[0289] - In the case where the conical phase mask used enables the SLM to simulate a negative axis prism (the Bessel ring 33a is located below the line of action used to perform the cutting), the cutting plane is below the focal plane of the cutting device, in which case the control unit 60 drives the optical focusing system 50 to focus the modulated and deflected laser beam 410 to a desired depth greater than the maximum depth of the cutting plane to be created.

[0290] The control unit 60 sends the conical phase mask (ie, the axicon modulation set points) to the shaping system 30 to generate a Bessel-type modulated laser beam (step E220 ).

[0291] The control unit 60 also initiates movement of the sweeping optical scanner 40 to the initial position of the second optical scanning path.

[0292] When the following conditions are met:

[0293] - the focusing system 50 and the optical scanner 40 are in place,

[0294] - the conical phase mask is loaded into the shaping system 30, and

[0295] - the pivoting speed of the mirror of the optical scanner 40 is constant,

[0296] The control unit 60 activates the femtosecond laser source 10 to emit laser pulses (step E230 ).

[0297] The femtosecond laser source 10 generates a laser beam 110 that passes through a shaping system 30. The shaping system 30 modulates the phase of the laser beam to generate a single Bessel-type modulated laser beam.

[0298] The Bessel-type modulated laser beam 310 exits the shaping system 30 and enters the optical scanner 40 which deflects the Bessel-type modulated laser beam 310 .

[0299] The modulated and deflected laser beam 410 enters the optical focusing system 50 which focuses the beam. Above or below the focal plane, the modulation setpoints (i.e., the conical phase mask) applied to the shaping system 30 enable the energy to be distributed to the lines of action. Figure 12 As shown in step 620a, the line of action generates an elliptical bubble extending parallel to the optical axis AA' of the cutting device.

[0300] The femtosecond laser 1 continues to emit further pulses in the form of a laser beam at a determined rate. Between each pulse, the mirror is pivoted by a specific angle so that the line of action moves along the second optical path and a new elliptical bubble is formed (step E240). Figure 12 As shown in step 620b, after a certain number of pulses, the new bubble is adjacent to the previously formed elliptical bubble, thereby forming a vertical cutting plane segment.

[0301] The operations of driving the femtosecond laser source 10 and scanning the optical scanner 40 are repeated to form a vertical cutting plane.

[0302] More specifically, the pivoting of the mirror between each pulse of the femtosecond laser source 10 causes the line of action to move and create a new elliptical bubble that is offset relative to the previous bubble until a cut portion is formed in the cutting plane, as shown in FIG. Figure 12 As shown in step 620c.

[0303] Once the cut portion has been completed, the control unit 60 deactivates the femtosecond laser source 10 and controls the movement of the optical focusing system to generate a second portion of the elliptical bubble above the first portion, and then controls the mirror to pivot in the opposite direction and activates the femtosecond laser source 10 again. Figure 12 As shown in step 630c.

[0304] The laser beam 110 passes through the shaping system 30, the optical scanner 40 and the optical focusing system 50. A new elliptical bubble portion is formed in the cutting plane, located above the previous portion and extending in the same plane as the previous portion.

[0305] When the optical scanner 40 has scanned all positions of the second moving path, the vertical cutting plane is completed.

[0306] In summary, in order to create a vertical cutting plane, the control unit 60 is configured to:

[0307] - applying an axicon modulation setpoint to a shaping system 30 in order to generate a Bessel-type modulated laser beam from a Gaussian laser beam, said modulation setpoint comprising a phase mask 314, 315 simulating an axicon applied to a spatial light modulator (SLM), said Bessel-type modulated laser beam generating a line of action capable of generating an elliptical bubble in tissue,

[0308] - Driving the sweeping optical scanner 40 to move the line of action of the Bessel-type modulated laser beam along the second optical movement path, thereby forming a vertical plane consisting of a group of adjacent elliptical bubbles.

[0309] Reference Figure 13 , partially illustrating a set of action lines L1 , L2 and L3 for creating stacked elliptical bubble portions, these action lines extending in a single vertical cutting plane between two horizontal cutting planes H1 , H2 .

[0310] like Figure 13 As shown, the lines of action used to form two consecutive stacked sections partially overlap. In fact, the inventors found that the ends of the lines of action did not have enough energy to form an elliptical bubble. Therefore, the inventors proposed overlapping the lines of action used to create the stacked elliptical bubble sections.

[0311] Specifically, after creating the horizontal cutting plane H1, the elliptical bubble segments are stacked (e.g. Figure 13 The first, second and third parts in the illustrated embodiment) are used to create a vertical cutting plane located above the horizontal cutting plane H1.

[0312] To create the first portion (i.e., the portion closest to the horizontal cutting plane H1), the control unit 60 is configured to drive the optical focusing system 50 so as to position the focal plane of the cutting device at a predetermined non-zero distance from the first horizontal cutting plane. This predetermined distance is less than the length of the line of action L1 of the Bessel-type modulated laser beam. In particular, the predetermined distance can be between 1 / 5 and 1 / 3 of the line of action length. Thus, each line of action L1 used to create the first portion partially intersects the horizontal cutting plane H1. The control unit 60 then drives the scanning optical scanner 40 to move the line of action L1 along the second optical movement path to form the first portion of the adjacent elliptical bubble.

[0313] To create the second portion (i.e., the portion located above the first portion), the control unit 60 is configured to drive the optical focusing system 50 to position the focal plane of the cutting device at a predetermined distance from the first portion of the elliptical bubble. Thus, each line of action L2 used to create the second portion partially overlaps the elliptical bubble of the first portion. The control unit 60 then drives the scanning optical scanner 40 to move the line of action L2 along a second optical movement path to form the second portion of the adjacent elliptical bubble.

[0314] In order to create the third portion (i.e., the portion farthest from the horizontal cutting plane H1), the control unit 60 is configured to drive the optical focusing system 50 so as to position the focal plane of the cutting device at a predetermined distance from the second portion so that the end of the action line L3 contacts the elliptical bubble of the second portion.

[0315] This ensures that the tissue bridges between the different stacked sections are narrow enough to enable the practitioner to perform a dissection of acceptable quality across the entire height of each vertical cutting plane.

[0316] 2.5.3. Forming stacked horizontal and vertical cutting planes to create an organizational cube

[0317] The working principle of the cutting device in lens destruction as part of cataract surgery will now be described in more detail.

[0318] In order to divide the lens into cubes that can be aspirated by the suction cannula, horizontal and vertical cutting planes are formed by starting from the deepest horizontal cutting plane in the lens and stacking consecutive vertical and horizontal cutting planes until the shallowest horizontal cutting plane in the lens.

[0319] Reference Figure 14 and Figure 15 , in the first step (E310, F310), the deepest horizontal cutting plane H1 is created. The control unit 60:

[0320] - applying a multi-point phase mask to the shaping system 30 to generate a multi-point modulated laser beam,

[0321] - controlling the movement of the focusing system 50 so that the focal plane of the cutting device coincides with the desired deepest cutting plane,

[0322] - driving the sweeping optical scanner along a (e.g. sawtooth-like) first optical path to a target position, and

[0323] - Start the femtosecond laser source 10 (after the scanner movement speed stabilizes and reaches the target position).

[0324] A series of shots are performed in the focal plane of the cutting device. During each shot, multiple points are simultaneously focused on the focal plane. Each point forms a bubble. The optical scanner is able to move the multiple points in the focal plane between shots. When the entire surface of the horizontal cutting plane is covered by the bubble, the horizontal cutting plane H1 is complete.

[0325] In the second step (E320 and F320), a first set of adjacent vertical cutting planes V1 are created using the cutting device. For each vertical cutting plane V1, the control unit 60:

[0326] - applying a conical phase mask to the shaping system 30 to produce a Bessel-type modulated laser beam,

[0327] - controlling the movement of the focusing system 50 so as to position the line of action in the cutting plane (the focusing plane is above or below the cutting plane depending on whether the axicon simulated by the shaping system is a positive or negative axicon),

[0328] - driving the sweeping optical scanner to move along a second optical path (e.g., a segment) to a target position, and

[0329] - Start the femtosecond laser source 10 (after the scanner movement speed stabilizes and reaches the target position).

[0330] A series of shots are performed. Each shot generates a line of action. Each line of action forms an elliptical bubble along the optical axis of the modulated laser beam. The sweeping optical scanner 40 can move the line of action above or below the focal plane between shots. When the entire second movement path is covered by the bubble, the vertical cutting plane V1 is complete.

[0331] If the depth of the line of action is less than the desired depth of the vertical cutting plane, the control unit 60 may regulate the sweeping optical scanner 40 and the optical focusing system 50 to move the line of action back and forth along the second optical path by changing the depth of the focal plane of the cutting device.

[0332] Thus, a plurality of vertical cutting planes V1 above the initial horizontal cutting plane H1 are obtained. These cutting planes V1 are divided into two subgroups ( Figure 2 The first subgroup plane 107' and the second subgroup plane 107" in the figure form parallel planes within the same subgroup, but the two different subgroups are perpendicular to each other, so that vertical cutting planes forming a grid pattern can be obtained, and each basic square represents the side wall of the cube cut thereby.

[0333] In the third step (E330, F330), an intermediate horizontal plane H2 is created to overlap the vertical cutting plane V1. This horizontal cutting plane H2 is created using the same method as described with reference to the first step. Thus, a lens cube is obtained, defined between the horizontal and vertical planes created in the first, second, and third steps.

[0334] In the fourth step (E340, F340), a second set of adjacent vertical cutting planes V2 is created using the cutting device. This second set of vertical cutting planes V2 is laterally offset relative to the first set of vertical cutting planes V1. To this end, the control unit 60 drives the scanning optical scanner 40 along a third movement path that is different from (specifically, laterally offset from) the second optical path. Consequently, none of the second set of vertical cutting planes V2 are coplanar with the first set of vertical cutting planes V1.

[0335] In a fifth step ( E350 , F350 ), the upper horizontal plane H3 is created using the same method as described with reference to step 1. Thus, a stack of two lens cubes is obtained, the second layer being laterally offset relative to the first.

[0336] The above steps can be repeated to perform a stacking of more than two layers of lens cubes, wherein the cubes of one layer are laterally offset relative to the underlying lens cubes supported thereunder.

[0337] 3. in conclusion

[0338] The lateral offset of the vertical cutting plane located above the horizontal cutting plane relative to the vertical cutting plane located below the horizontal cutting plane can limit the propagation of gas bubbles to the surface of the tissue to be treated.

[0339] As previously mentioned, in the case of ocular tissue cutting, this propagation may cause gas to accumulate above the cutting plane in the lens, or even above the lens in the anterior chamber of the eye, and obscure the laser beam, thereby preventing cutting of the anterior portion of the lens.

[0340] The present invention thus provides an efficient three-dimensional cutting tool which enables cutting into elementary parts of small dimensions of equal size.

[0341] The reader will appreciate that many modifications may be made to the above-described invention without materially departing from the novel teachings and advantages described herein.

Claims

1. A device for cutting human or animal tissue, the device comprising a femtosecond laser source (10) configured to emit a Gaussian laser beam in pulsed form 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) located on the trajectory of the Gaussian laser beam to modulate the phase of the wavefront of the Gaussian laser beam, the shaping system (30) comprising a spatial light modulator (SLM) and configured to generate a modulated laser beam from the Gaussian laser beam, - a sweeping optical 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 on the focal plane of the cutting device and for moving the focal plane of the cutting device to a plurality of positions along the optical axis of propagation (A-A') of the modulated laser beam, The processing device further comprises a control unit (60) for driving the femtosecond laser source (10), the shaping system (30), the sweeping optical scanner (40) and the optical focusing system (50) to create continuous horizontal cutting planes and vertical cutting planes, wherein the horizontal cutting planes extend perpendicular to the optical axis (A-A') and the vertical cutting planes extend parallel to the optical axis (A-A'), and the control unit (60) is configured as follows: - Control (E310) the creation of the first horizontal cutting plane (H1), - controlling ( E320 ) the creation of a first plurality of vertical cutting planes ( V1 ) above the first horizontal cutting plane ( H1 ), - controlling ( E330 ) the creation of a second horizontal cutting plane ( H2 ) above the first plurality of vertical cutting planes ( V1 ), the first horizontal cutting plane ( H1 ) being located deeper in the tissue than the second horizontal cutting plane ( H2 ), - Controlling ( E340 ) the creation of a second plurality of vertical planes ( V2 ) above the second horizontal plane ( H2 ), wherein the second plurality of vertical cutting planes ( V2 ) are laterally offset relative to the first plurality of vertical planes ( V1 ).

2. The cutting device according to claim 1, wherein The second plurality of vertical cutting planes are laterally offset relative to the first plurality of vertical cutting planes by a distance between 5 μm and 500 μm.

3. The cutting device according to any one of claims 1 or 2, wherein: The second plurality of vertical cutting planes are laterally offset relative to the first plurality of vertical cutting planes along first and second axes perpendicular to the optical axis (AA'), the first and second axes being orthogonal to each other.

4. The cutting device according to any one of claims 1 to 3, wherein: In order to create each horizontal cutting plane, the control unit (60) is configured to: o applying a multi-point phase mask to a shaping system (30) to generate a single multi-point modulated laser beam (E120), calculating the multi-point phase mask to distribute the energy of the multi-point modulated laser beam to at least two points in the focal plane of the cutting device, o controlling the movement of the focusing system (50) so that the focal plane of the cutting device coincides with the desired depth of the horizontal cutting plane (E110), o driving the scanning optical scanner so that the point of action of the single multi-point modulated laser beam moves along a first movement path (E140), o Start the femtosecond laser source (10) (E130).

5. The cutting device according to any one of claims 1 to 4, wherein: In order to create each of the first plurality of vertical cutting planes (V1), the control unit (60) is configured to: o applying an axicon modulation setpoint to a shaping system (30) to generate a Bessel-type modulated laser beam (E220) from a Gaussian laser beam, the modulation setpoint comprising a phase mask (314, 315) simulating an axicon applied to a spatial light modulator (SLM), the Bessel-type modulated laser beam generating a line of action capable of generating an elliptical bubble in tissue, o Driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam along the second optical movement path to form a group of adjacent elliptical bubbles (E240).

6. The cutting device according to claim 5, wherein: In order to create each of the second plurality of vertical cutting planes (V2), the control unit (60) is configured to: o Applying the axicon modulation setpoint to the shaping system (30) (E220), o Driving the sweep optical scanner to move the line of action of the Bessel-type modulated laser beam along a third optical path that is laterally offset relative to the second optical path ( E240 ).

7. The cutting device according to any one of claims 5 or 6, wherein: Each vertical cutting plane is composed of a stack of multiple groups of adjacent elliptical bubbles, and the control unit (60) is configured as follows: actuating the optical focusing system so as to position the focal plane of the cutting device at a predetermined non-zero distance (50) from the first horizontal cutting plane, said predetermined distance being less than the length of the line of action of the Bessel-type modulated laser beam, so that the line of action partially intersects the first horizontal cutting plane, o driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam to form a first group of adjacent elliptical bubbles, o driving the optical focusing system (50) so as to position the focal plane of the cutting device at a predetermined distance from the first group of adjacent elliptical bubbles so that the line of action partially intersects the first group of adjacent elliptical bubbles, o Driving the sweeping optical scanner to move the line of action of the Bessel-type modulated laser beam to form a second group of adjacent elliptical bubbles.

8. The cutting device according to claim 7, wherein: The predetermined distance is between 1 / 5 and 1 / 3 of the length of the line of action.

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