Systems and methods

Abstract

Method and apparatus for modifying a substrate - Patents.com A method for modifying a substrate comprises generating a pulsed laser beam comprising a train of laser pulses, the train of laser pulses comprising at least three consecutive laser pulses; and controlling a direction of the pulsed laser beam and / or a position of the substrate for each laser pulse such that the at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence defining relative spatial positions of the at least three regions of the substrate and an order of irradiation of the at least three regions of the substrate. An apparatus for modifying a substrate is also described. The method and apparatus may be particularly, but not exclusively, used to form optical devices.

Description

[Technical Field]

[0001] The present disclosure relates to methods and apparatus for modifying substrates using pulsed laser beams, particularly but not exclusively for use in the formation of optical devices. [Background technology]

[0002] It is known to use laser processing methods to modify substrates or bodies containing materials such as fused silica by irradiating the substrate with a pulsed laser beam. The pulsed laser beam can be used to irradiate one or more localized regions or volumes of the substrate, thereby modifying the one or more irradiated regions or volumes. For example, it is known to irradiate a region of a substrate with a pulsed laser beam to modify the refractive index of the substrate material in the irradiated region. It is also known to irradiate a region of a substrate with a pulsed laser beam to modify the chemical etchability of the substrate material in the irradiated region. This may enable 3D micromachining of the substrate using a chemical etching step after irradiating the substrate with the pulsed laser beam. It is also known to irradiate a region of a substrate with a pulsed laser beam to remove at least a portion of the substrate material in the irradiated region.

[0003] In some applications, it is known to irradiate multiple regions of a substrate by moving the pulsed laser beam and the substrate relative to each other to modify the material of the substrate according to a desired spatial profile. To modify the material of the substrate according to the desired spatial profile while avoiding excessive damage to the substrate, the characteristics of the pulsed laser beam and the relative movement between the pulsed laser beam and the substrate need to be carefully controlled to comply with a set of laser processing conditions or rules, i.e., so that the characteristics of the pulsed laser beam and the relative movement between the pulsed laser beam and the substrate fall within a predetermined laser processing condition window.

[0004] However, for a given predetermined laser processing condition window, the throughput of such known laser processing methods for modifying multiple regions of a substrate may be limited. Summary of the Invention

[0005] According to an aspect of the present disclosure, there is provided a method for modifying a substrate, the method comprising: generating a pulsed laser beam comprising a train of laser pulses, the train of laser pulses comprising at least three consecutive laser pulses; and controlling a direction of the pulsed laser beam and / or a position of the substrate for each laser pulse such that the at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence defining relative spatial positions of the at least three regions of the substrate and an order of irradiation of the at least three regions of the substrate.

[0006] Optionally, the at least three regions of the substrate are different, separate, and / or non-overlapping regions of the substrate.

[0007] Such methods may allow a substrate to be modified according to a desired spatial profile at higher laser pulse repetition rates than prior art methods without excessively damaging the substrate. Such methods may allow a substrate to be modified more rapidly than prior art methods, thereby achieving higher laser processing throughput.

[0008] The method may comprise irradiating the substrate with a pulsed laser beam to modify the refractive index of the material of the substrate.

[0009] The method may comprise irradiating the substrate with a pulsed laser beam to modify the chemical etchability of a material of the substrate.The method may comprise exposing the substrate to a chemical etchant after irradiating the substrate with the pulsed laser beam.

[0010] The method may comprise irradiating the substrate with a pulsed laser beam to remove material of the substrate.

[0011] The method may comprise controlling one or more properties of the pulsed laser beam.

[0012] The method may comprise controlling one or more of the energy of each pulse in the pulsed laser beam, the repetition frequency of the pulsed laser beam, the pulse duration, the wavelength of the pulsed laser beam, and the polarization of the pulsed laser beam.

[0013] The pulsed laser beam may include visible or non-visible light, for example, the pulsed laser beam may include one or more of infrared, visible, or ultraviolet light.

[0014] The pulsed laser beam may have a wavelength greater than 400 nm. For example, the pulsed laser beam may have a wavelength substantially equal to 520 nm, 800 nm, 1035 nm, or 1550 nm.

[0015] The substrate may include a material, such as a dielectric material, that is at least partially transparent to the pulsed laser beam. For example, the substrate may include a glass or glass-ceramic material, such as fused silica, silicates, borosilicates, aluminosilicates, doped or modified silicates, phosphate glasses, doped or modified phosphates, chalcogenide glasses, or doped or modified chalcogenides. The substrate may include materials other than glass. The substrate may include a laser or amplifier gain medium, such as a quartz crystal material, lithium niobate, such as periodically poled lithium niobate or neodymium-doped yttrium aluminum garnet, yttrium aluminum garnet, or a doped, poled, or modified quartz crystal, rare earth-doped glass or quartz crystal.

[0016] Optionally, controlling the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse such that the at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence includes synchronizing movement of the pulsed laser beam and / or the substrate with the timing of the at least three successive laser pulses such that the at least three regions of the substrate are sequentially irradiated with the at least three successive laser pulses according to a predetermined spatial sequence, which may allow for more precise control of the positions of the at least three irradiated regions of the substrate.

[0017] Optionally, controlling the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse such that at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence comprises: controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate such that a first of the at least three successive laser pulses irradiates a first region of the substrate centered at the first position; controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate along a first direction from a first position on the substrate to a second position on the substrate such that a second of the at least three successive laser pulses irradiates a second region of the substrate centered at the second position; and controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate along a second direction from a second position on the substrate to a third position on the substrate such that a third of the at least three successive laser pulses irradiates a third region of the substrate centered at the third position. wherein the first and second directions are different.

[0018] Optionally, the first, second and third regions of the substrate are different, separate and / or non-overlapping regions of the substrate.

[0019] Optionally, the first, second and third locations on the substrate are different locations on the substrate.

[0020] Optionally, the third region of the substrate is located closer to the first region than the second region.

[0021] Optionally, a third region of the substrate is located between the first and second regions of the substrate.

[0022] Optionally, the method comprises irradiating any two nearest neighboring regions of the substrate with laser pulses separated by a duration greater than or equal to a predetermined minimum duration.

[0023] The minimum period may be selected for compliance of the method with a predetermined laser processing condition window.

[0024] The predetermined minimum period may be selected such that the temperature of any two nearest neighboring regions of the substrate is less than or equal to a predetermined threshold temperature.

[0025] The laser pulse characteristics of the pulsed laser beam can be selected so that irradiation of an area of ​​the substrate with the laser pulse results in multiphoton absorption of the laser pulse in the material of the substrate in the irradiated area and heating of the material of the substrate in the irradiated area. The resulting thermal energy generated in the irradiated area diffuses from the irradiated area through the substrate, causing the irradiated area to cool over time. Thus, by selecting a predetermined minimum period such that the temperature of any two nearest neighboring areas of the substrate is less than or equal to a predetermined threshold temperature, the method can ensure compliance with a predetermined laser processing condition window, thereby allowing the substrate to be modified according to a desired spatial profile at higher laser pulse repetition rates than prior art methods without excessively damaging the substrate.

[0026] Optionally, the method comprises irradiating any two regions of the substrate with successive laser pulses, wherein the any two regions of the substrate are separated by a distance greater than or equal to a predetermined minimum spatial separation.

[0027] The minimum spatial separation may be selected for compliance of the method with a predetermined laser processing condition window.

[0028] The predetermined minimum spatial separation may be selected such that the temperature of any two regions of the substrate is less than or equal to a predetermined threshold temperature.

[0029] The laser pulse characteristics of the pulsed laser beam can be selected such that irradiation of an area of ​​the substrate with the laser pulse results in multiphoton absorption of the laser pulse in the material of the substrate in the irradiated area and heating of the material of the substrate in the irradiated area. The resulting thermal energy generated in the irradiated area diffuses from the irradiated area through the substrate, causing the irradiated area to cool over time. Thus, by selecting a predetermined minimum spatial separation such that the temperature of any two areas of the substrate exceeds a predetermined threshold temperature, the method can ensure compliance with a predetermined laser processing condition window, thereby allowing the substrate to be modified according to a desired spatial profile at higher laser pulse repetition rates than prior art methods without excessively damaging the substrate.

[0030] The at least three regions of the substrate may be arranged in an array, such as a 1D array, a 2D array, or a 3D array.

[0031] Compared to irradiating a 1D array of regions of a substrate, irradiating a 2D array of regions of a substrate may provide additional degrees of freedom for selecting the sequence in which the regions of the substrate are irradiated. For example, compared to irradiating a 1D array of regions of a substrate, irradiating a 2D array of regions of a substrate may allow the use of higher laser pulse repetition frequencies while still operating within the laser processing condition window because sequential laser pulses can be used to irradiate regions of the substrate that are spaced a greater distance apart and / or because nearest neighboring regions of the substrate can be irradiated with non-sequential laser pulses that are spaced a longer period apart.

[0032] Compared to irradiating a 2D array of regions of a substrate, irradiating a 3D array of regions of a substrate may provide additional degrees of freedom for selecting the sequence in which the regions of the substrate are irradiated. For example, compared to irradiating a 2D array of regions of a substrate, irradiating a 3D array of regions of a substrate may allow the use of higher laser pulse repetition frequencies while still operating within the laser processing condition window because sequential laser pulses can be used to irradiate regions of the substrate that are spaced a greater distance apart and / or because nearest neighboring regions of the substrate can be irradiated with non-sequential laser pulses that are spaced a longer period apart.

[0033] The multiple regions of the substrate may be arranged in a uniform array, such as a uniform 1D array, a uniform 2D array, or a uniform 3D array.

[0034] The method may comprise irradiating at least three regions of the substrate with a pulsed laser beam to modify the substrate according to a desired spatial profile.

[0035] The method may include irradiating a substrate with a pulsed laser beam to create or define one or more features or structures in the substrate. Each feature or structure may be configured to transmit, reflect, refract, and / or diffract light. Each feature or structure may comprise an optical device. Each feature or structure may be configured to guide light. Each feature or structure may be configured to position and / or align a separately formed optical component with respect to the substrate. Each feature or structure may be configured to position and / or align a separately formed optical waveguide or optical fiber with respect to the substrate.

[0036] Optionally, the method comprises irradiating one or more of the at least three regions of the substrate with a corresponding single laser pulse of the series of laser pulses.

[0037] Optionally, the method includes irradiating one or more of the at least three regions of the substrate with a corresponding plurality of non-contiguous laser pulses of the series of laser pulses. Such a method may allow different regions of the at least three regions of the substrate to receive different total amounts of irradiation while still complying with the laser processing condition window. This may be useful for varying the degree of modification between different regions of the substrate, for example, for varying refractive index modification between different regions of the substrate according to a desired refractive index profile.

[0038] Optionally, controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis includes controlling movement of the pulsed laser beam relative to the substrate on a laser pulse-by-laser pulse basis, for example by steering the pulsed laser beam relative to the substrate.

[0039] Optionally, controlling the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse includes controlling movement of the substrate relative to the pulsed laser beam. For example, the method may comprise controlling movement of the substrate relative to the pulsed laser beam in a direction parallel to the surface of the substrate. The method may comprise controlling movement of the substrate relative to the pulsed laser beam in a direction perpendicular to the surface of the substrate. The method may comprise controlling movement of the substrate in a direction of propagation of the pulsed laser beam. The method may comprise controlling movement of the substrate in a direction opposite to the direction of propagation of the pulsed laser beam. Such a method may allow the substrate to be modified in 3D.

[0040] Optionally, controlling the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse includes controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate at a varying speed during which at least three consecutive laser pulses irradiate at least three regions of the substrate.

[0041] Optionally, the velocity includes first and second velocity components.

[0042] Optionally, the first velocity component is constant and the second velocity component is variable.

[0043] Optionally, the first velocity component varies slower than the second velocity component.

[0044] Optionally, the first velocity component is unidirectional.

[0045] Optionally, the second velocity component varies in magnitude and / or direction.

[0046] Optionally, the first velocity component is associated with movement of the substrate relative to the pulsed laser beam.

[0047] Optionally, the second velocity component is associated with movement of the pulsed laser beam relative to the substrate, for example, the second velocity component is associated with beam steering of the pulsed laser beam relative to the substrate.

[0048] The method may include using a beam scanner to control the direction of the pulsed laser beam on a laser pulse-by-laser pulse basis, such that at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence defining the relative spatial positions of the at least three regions of the substrate and an irradiation order of the at least three regions of the substrate.

[0049] The method may comprise using a further beam scanner to impart additional relative motion between the pulsed laser beam and the substrate to the relative motion between the pulsed laser beam and the substrate provided by the beam scanner.

[0050] The beam scanner may have a response time that is faster than the response time of the further beam scanner.

[0051] Response time may refer to the time between when the beam scanner (or further beam scanner) receives an input signal specifying a new configuration or state for the beam scanner (or further beam scanner) and when the beam scanner (or further beam scanner) changes its configuration or state to match the new configuration or state.

[0052] The beam scanner may be configured to move, eg steer, the pulsed laser beam faster than the further beam scanner.

[0053] The additional beam scanner may provide an associated range of movement of the pulsed laser beam that is greater than the range of movement of the pulsed laser beam associated with the beam scanner. The additional beam scanner may be operable to steer the pulsed laser beam over a greater angular range than the beam scanner.

[0054] By using the beam scanner and the further beam scanner in this combination, it may be possible to move the pulsed laser beam relative to the substrate over a greater distance than would be possible using the beam scanner alone, while also being able to irradiate at least three regions of the substrate according to a desired spatial profile at a higher laser pulse repetition frequency than prior art methods, without excessively damaging the substrate.

[0055] The beam scanner may include a non-mechanical beam scanner. The beam scanner may include a solid-state beam scanner. The beam scanner may include an acousto-optic modulator beam scanner. The beam scanner may include an electro-optic modulator beam scanner.

[0056] The further beam scanner may include a mechanical beam scanner. The further beam scanner may include one or more moving parts. The further beam scanner may include a galvanometer beam scanner. The further beam scanner may include a tilt mirror beam scanner.

[0057] The method may include moving the substrate relative to the pulsed laser beam using a movable stage, such as a motion-controlled stage or a translation stage to which the substrate is fixed. The use of a movable stage may allow a larger area of ​​the substrate to be irradiated with the pulsed laser beam than would be possible by using a beam scanner and / or further beam scanner to move the pulsed laser beam relative to the substrate.

[0058] The method can include moving the substrate relative to the pulsed laser beam while moving the pulsed laser beam relative to the substrate.

[0059] The method may include moving the substrate relative to the pulsed laser beam using a movable stage while moving the pulsed laser beam relative to the substrate using a beam scanner, and optionally also using a further beam scanner.

[0060] The method may include generating a synchronization control or trigger signal and using the synchronization control or trigger signal to synchronize relative movement between the substrate and the pulsed laser beam with the timing of the laser pulses of the series of laser pulses.

[0061] The method may include using a photodetector, such as a high-speed photodetector, to detect a portion of the pulsed laser beam and thereby generate a synchronization control signal.

[0062] The method may include using a pulse picker to control timing of laser pulses of the series of laser pulses in accordance with a synchronization control signal to synchronize relative movement between the substrate and the pulsed laser beam with the timing of the laser pulses of the series of laser pulses.

[0063] The method may include using a synchronization control signal to trigger or initiate emission of each laser pulse of the series of laser pulses from the pulsed laser, and using the synchronization control signal to synchronize relative movement between the substrate and the pulsed laser beam with the timing of the laser pulses of the series of laser pulses.

[0064] The method may comprise using a synchronized control signal to trigger generation of a predetermined waveform for controlling the sequence of irradiation of at least three areas of the substrate by the pulsed laser beam, which may allow for more precise control of the location of the irradiation areas on the substrate.

[0065] The method may comprise using a synchronized control signal to trigger an arbitrary waveform generator to generate a predetermined waveform for controlling the sequence of irradiation of at least three regions of the substrate by the pulsed laser beam.

[0066] The method may comprise determining or measuring emission timing data for one or more of the laser pulses. For example, the method may comprise detecting a portion of a pulsed laser beam to thereby measure emission timing data for one or more laser pulses emitted from the pulsed laser.

[0067] The method may include determining or measuring a nominal writing position of the pulsed laser beam at the substrate. The method may include determining or measuring a velocity of the nominal writing position of the pulsed laser beam across the substrate. The method may include calculating a predicted nominal writing position of the pulsed laser beam at the substrate upon emission of a future laser pulse at the substrate using the measured emission timing data and at least one of the determined or measured nominal writing position of the pulsed laser beam at the substrate and the determined or measured velocity of the nominal writing position of the pulsed laser beam at the substrate. The method may include compensating for any difference between the predicted nominal writing position of the pulsed laser beam at the substrate and a corresponding desired nominal writing position of the pulsed laser beam at the substrate. For example, the method may include controlling a beam steering configuration of a beam scanner and / or a rate of change of the beam steering configuration of the beam scanner to compensate for any difference between the predicted nominal writing position of the pulsed laser beam at the substrate and the desired nominal writing position of the pulsed laser beam at the substrate.

[0068] The method may comprise adjusting the timing of the emission of future laser pulses to compensate for any difference between the predicted nominal writing position of the pulsed laser beam on the substrate and the desired nominal writing position of the pulsed laser beam on the substrate.

[0069] By compensating for any differences between the predicted nominal writing position of the pulsed laser beam on the substrate and the desired nominal writing position of the pulsed laser beam on the substrate in this manner, it may be possible to irradiate multiple regions of the substrate with greater positional accuracy. This may improve the positional accuracy of any features created by modifying the substrate. This may minimize any unwanted spatial variations in the resulting substrate modification. For example, this may minimize any unwanted variations in the refractive index of the substrate. This may minimize any unwanted variations in the etchability of the substrate. This may minimize any unwanted surface roughness of the substrate following subsequent chemical etching of the substrate and / or modification of the substrate by removal of material from the substrate.

[0070] The method may include determining or measuring a beam steering configuration, such as one or more tilt angles, of the slower beam scanner. The method may include measuring the beam steering configuration of the slower beam scanner using one or more sensors, such as one or more rotary encoders. The method may include determining or measuring a rate of change of the beam steering configuration, such as a rate of change of one or more tilt angles of the slower beam scanner. The method may include using one or more sensors, such as one or more rotary encoders, to measure the rate of change of the beam steering configuration of the slower beam scanner. The method may include calculating a predicted beam steering configuration of the slower beam scanner at the time of emission of a future laser pulse using at least one of the determined or measured emission timing data, the determined or measured beam steering configuration of the slower beam scanner, and the determined or measured rate of change of the beam steering configuration of the slower beam scanner. The method may include using the faster beam scanner to compensate for any difference between the predicted beam steering configuration of the slower beam scanner at the time of emission of a future laser pulse and a desired beam steering configuration of the slower beam scanner. For example, the method may include controlling the beam steering configuration of the faster beam scanner and / or the rate of change of the beam steering configuration of the faster beam scanner to compensate for any difference between the predicted beam steering configuration of the slower beam scanner at the time of emission of the future laser pulse and the desired beam steering configuration of the slower beam scanner at the time of emission of the future laser pulse.

[0071] The faster beam scanner may be used in this manner to allow each region of the substrate to be irradiated with greater positional accuracy by compensating for any difference between the beam steering configuration of the slower beam scanner at the time of emission of a future laser pulse and the desired beam steering configuration of the slower beam scanner. This may improve the positional accuracy of any features created by modifying the substrate. This may minimize any unwanted spatial variations in the resulting substrate modification. For example, this may minimize any unwanted variations in the refractive index of the substrate. This may minimize any unwanted variations in the etchability of the substrate. This may minimize any unwanted surface roughness of the substrate following subsequent chemical etching of the substrate and / or modification by removal of material from the substrate. As the speed of the slower beam scanner is increased, the difference between the measured beam steering configuration of the slower beam scanner and the desired future beam steering configuration of the slower beam scanner may increase. Therefore, using the faster beam scanner in this manner to compensate for any differences between the predicted beam steering configuration of the slower beam scanner and the desired future beam steering configuration of the slower beam scanner can mean that the slower beam scanner can be operated faster without unduly reducing the positional accuracy with which the pulsed laser beam can irradiate each region of the substrate, thereby increasing overall laser processing throughput.

[0072] The series of laser pulses may be periodic.

[0073] The train of laser pulses may have a repetition rate of at least 100 KHz, at least 1 MHz, at least 2 MHz, at least 5 MHz, or at least 10 MHz.

[0074] The train of laser pulses can be generated using a Q-switched or mode-locked laser.

[0075] The train of laser pulses can be generated using a laser in combination with an optical modulator.

[0076] According to an aspect of the present disclosure, there is provided an apparatus for modifying a substrate, the apparatus comprising: a pulsed laser for generating a pulsed laser beam comprising a train of laser pulses comprising at least three consecutive laser pulses; and an irradiation control mechanism for controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence defining the relative spatial positions and order of irradiation of the at least three regions of the substrate; Equipped with.

[0077] Optionally, the at least three regions of the substrate are different, separate, and / or non-overlapping regions of the substrate.

[0078] The irradiation control mechanism may be configured to control the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse, such that at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence by synchronizing movement of the pulsed laser beam and / or the substrate with the timing of the at least three successive laser pulses, such that at least three regions of the substrate are sequentially irradiated with the at least three successive laser pulses according to a predetermined spatial sequence.

[0079] by controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate such that a first of the at least three successive laser pulses irradiates a first region of the substrate centered at the first position; by controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate along a first direction from a first position on the substrate to a second position on the substrate such that a second of the at least three successive laser pulses irradiates a second region of the substrate centered at the second position; and by controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate along a second direction from a second position on the substrate to a third position on the substrate such that a third of the at least three sequential laser pulses irradiates a third region of the substrate centered at the third position; The irradiation control mechanism may be configured to control the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis, such that at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence, where the first and second directions are different.

[0080] Optionally, the first, second and third regions of the substrate are different, separate and / or non-overlapping regions of the substrate.

[0081] Optionally, the first, second and third locations on the substrate are different locations on the substrate.

[0082] The third region of the substrate may be located closer to the first region than the second region.

[0083] The illumination control mechanism may include a beam scanner for controlling a nominal writing position of the pulsed laser beam on the substrate. The beam scanner may include a non-mechanical beam scanner. The beam scanner may include a solid-state beam scanner. The beam scanner may include an acousto-optic modulator beam scanner. The beam scanner may include an electro-optic modulator beam scanner.

[0084] The illumination control mechanism may include a further beam scanner for controlling the nominal writing position of the pulsed laser beam on the substrate.

[0085] The further beam scanner may include a mechanical beam scanner. The further beam scanner may include one or more moving parts. The further beam scanner may include a galvanometer beam scanner. The further beam scanner may include a tilt mirror beam scanner.

[0086] The beam scanner may be configured to rotate the direction of the pulsed laser beam about one axis.

[0087] The beam scanner may be configured to rotate the direction of the pulsed laser beam about two non-parallel axes, for example, two orthogonal axes.

[0088] The beam scanner may include a first beam scanner element for varying the angle of the pulsed laser beam about a corresponding first axis, and a second beam scanner element for varying the angle of the pulsed laser beam about a corresponding second axis, where the first and second axes are non-parallel, e.g., orthogonal.

[0089] The beam scanner may include a first lens and a second lens. The first and second lenses may be arranged in a 4f configuration, where the first and second lenses are separated by a distance of 2f, the first beam scanner element is located at the back focal plane of the first lens, and the second beam scanner element is located at the front focal plane of the second lens. Alternatively, the beam scanner may include a half-pitch GRIN rod lens. The first beam scanner element may be located at a first end of the half-pitch GRIN rod lens, and the second beam scanner element may be located at a second end of the half-pitch GRIN rod lens. Such a beam scanner including a half-pitch GRIN rod lens may function to reduce variations in optical path length experienced by the pulsed laser beam because the direction of the pulsed laser beam is scanned by the first beam scanner element compared to a beam scanner including a first and second lens in a 4f configuration. Such a beam scanner including a half-pitch GRIN rod lens may also improve robustness and / or facilitate optical alignment compared to a beam scanner including a first and second lens in a 4f configuration.

[0090] One or each of the first and second beam scanner elements may include a non-mechanical beam scanner element. One or each of the first and second beam scanner elements may include a solid-state beam scanner element. One or each of the first and second beam scanner elements may include an acousto-optic modulator beam scanner element. One or each of the first and second beam scanner elements may include an electro-optic modulator beam scanner element.

[0091] The further beam scanner may be configured to rotate the direction of the pulsed laser beam about one axis.

[0092] The further beam scanner may be configured to rotate the direction of the pulsed laser beam about two non-parallel axes, for example two orthogonal axes.

[0093] The illumination control mechanism may include a third lens and a fourth lens. The beam scanner, the third and fourth lenses, and the further beam scanner may be arranged in a 4f configuration, where the third and fourth lenses are separated by a distance of 2f, the beam scanner is located at a back focal plane of the third lens, and the further beam scanner is located at a front focal plane of the fourth lens.

[0094] The illumination control mechanism may include a fifth lens, a sixth lens, and a microscope objective lens. The further beam scanner, the fifth and sixth lenses, and the microscope objective lens may be arranged in a 4f configuration, where the fifth and sixth lenses are separated by a distance of 2f, and the further beam scanner is located at a back focal plane of the fifth lens and the microscope objective lens is located at a front focal plane of the sixth lens.

[0095] The irradiation control mechanism may include a movable stage for moving the substrate relative to the pulsed laser beam, which may include a motion control stage or a translation stage to which the substrate is fixed.

[0096] The apparatus may be configured to generate a synchronization control signal and use the synchronization control signal to synchronize relative movement between the substrate and the pulsed laser beam with the timing of the laser pulses in the series of laser pulses.

[0097] The apparatus may include a detector, such as a high speed photodetector, for detecting a portion of the pulsed laser beam, thereby generating a synchronization control signal.

[0098] The illumination control mechanism may be configured to generate a predetermined sequence for irradiating at least three regions of the substrate with the pulsed laser beam using a synchronized control signal.

[0099] The illumination control mechanism may include an arbitrary waveform generator configured to use a synchronized control signal to generate a predetermined waveform for controlling the sequence of illumination of the at least three regions of the substrate with the pulsed laser beam.

[0100] It should be understood that any one or more of the features of any one of the above aspects of the present disclosure may be combined with any one or more of the features of any of the other above aspects of the present disclosure. [Brief explanation of the drawings]

[0101] These and other aspects of the present disclosure will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0102] [Figure 1] 1 shows a schematic diagram of an apparatus for modifying a substrate. [Figure 2] 1 shows a flow chart detailing a method for modifying a substrate. [Figure 3] Using the method of FIG. 2, first, second, third, and fourth pulse spatial sequences for use in modifying a substrate in 1D are shown. [Figure 4A] 4 shows a graph illustrating the position of the area of ​​the substrate irradiated by each laser pulse as a function of time for the laser pulse according to the first pulse spatial sequence of FIG. 3. [Figure 4B] 4B shows a graph showing the contribution of a faster beam scanner to the graph of FIG. 4A separated from the contribution of a slower additional beam scanner. [Figure 5A] 4 shows a graph illustrating the position of the area of ​​the substrate irradiated by each laser pulse as a function of time for the laser pulse according to the second pulse spatial sequence of FIG. 3. [Figure 5B] 5B shows a graph showing the contribution of a faster beam scanner to the graph of FIG. 5A separated from the contribution of a slower additional beam scanner. [Figure 6A] 4 shows a graph illustrating the position of the area of ​​the substrate irradiated by each laser pulse as a function of time for the laser pulse according to the third pulse spatial sequence of FIG. 3; [Figure 6B] 6B shows a graph showing the contribution of a faster beam scanner to the graph of FIG. 6A separated from the contribution of a slower additional beam scanner. [Figure 7A]4 shows a graph illustrating the position of the area of ​​the substrate irradiated by each laser pulse as a function of time for the laser pulse according to the fourth pulse spatial sequence of FIG. 3. [Figure 7B] 7B shows a graph showing the contribution of a faster beam scanner to the graph of FIG. 7A separated from the contribution of a slower additional beam scanner. [Figure 8] 3 shows a first pulse spatial sequence for use in modifying a substrate in 2D using the method of FIG. 2, showing the 2D location of the area of ​​the substrate irradiated by each laser pulse. [Figure 9] 3 shows a second pulse spatial sequence for use in modifying a substrate in 2D using the method of FIG. 2, showing the 2D location of the area of ​​the substrate irradiated by each laser pulse. [Figure 10] 10 shows a third pulse spatial sequence for use in modifying a substrate in 2D using the method of FIG. 2, showing the 2D location of the area of ​​the substrate irradiated by each laser pulse. [Figure 11] 10 shows a fourth pulse spatial sequence for use in modifying a substrate in 2D using the method of FIG. 2, showing the 2D location of the area of ​​the substrate irradiated by each laser pulse. [Figure 12] 10 shows a fifth pulse spatial sequence for use in modifying a substrate in 2D using the method of FIG. 2, showing the 2D location of the area of ​​the substrate irradiated by each laser pulse. [Figure 13] FIG. 2 shows a schematic diagram of an alternative two-axis beam scanner for use in the apparatus of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0103] 1 shows a schematic diagram of an apparatus 100 for modifying a substrate 108. The apparatus 100 includes a pulsed laser 102 and an irradiation control mechanism 103.

[0104] The pulsed laser 102 is a pulsed femtosecond laser for emitting a pulsed laser beam 150 in the form of a train of laser pulses, having a wavelength in the region of 1035 nm, a repetition rate in the range of 100 KHz to 10 MHz, and a pulse energy in the range of 100 to 2000 nJ.

[0105] The irradiation control mechanism 103 includes a beam steering mechanism 104 and a movable stage 109. The substrate 108 is fixed to the movable stage 109.

[0106] The beam steering mechanism 104 includes a two-axis beam scanner 120 in the form of a two-axis acousto-optic modulator (AOM) beam scanner, an optical relay system 126, a further two-axis beam scanner 122 in the form of a two-axis galvanometer beam scanner, a further optical relay system 144, and a microscope objective lens 148.

[0107] Two-axis AOM beam scanner 120 includes a first one-axis beam scanner element 130 in the form of a first one-axis acousto-optic modulator (AOM) beam scanner element, and a second one-axis beam scanner element in the form of a second one-axis AOM beam scanner element 134. Beam scanner 120 further includes a first lens 132 and a second lens 133. First beam scanner element 132, first lens 132, second lens 133, and second beam scanner element 134 are arranged in a 4f configuration, where first and second lenses 132, 133 are separated by a distance of 2f, first beam scanner element 130 is located at the back focal plane of first lens 132, and second beam scanner element 134 is located at the front focal plane of second lens 133.

[0108] To achieve 2D beam steering, the first and second beam scanner elements 130, 134 are arranged orthogonal to each other. Specifically, the first beam scanner element 130 is configured to control the direction of the pulsed laser beam 150 by rotating the pulsed laser beam 150 about the y-axis, and the second beam scanner element 134 is configured to control the direction of the pulsed laser beam 150 by rotating the pulsed laser beam 150 about the x-axis.

[0109] The optical relay system 126 includes a third lens 136 and a fourth lens 137. The second beam scanner element 134, the third lens 136, the fourth lens 137, and the further beam scanner 122 are arranged in a 4f configuration. Specifically, the third and fourth lenses 136, 137 are separated by a distance of 2f, with the second beam scanner element 134 of the beam scanner 120 located at the back focal plane of the third lens 136 and the galvanometer beam scanner 122 located at the front focal plane of the fourth lens 137.

[0110] The further optical relay system 144 includes a fifth lens 140 in the form of a scan lens and a sixth lens 142 in the form of a tube lens. The galvanometer beam scanner 122, the fifth lens 140, the sixth lens 142, and the microscope objective lens 148 are arranged in a 4f configuration, where the fifth and sixth lenses 140, 142 are separated by a distance of 2f, the galvanometer beam scanner 122 is located at the back focal plane of the fifth lens 140, and the microscope objective lens 148 is located at the front focal plane of the sixth lens 142.

[0111] The illumination control mechanism 103 further includes a photodetector 110 in the form of a high-speed photodetector, a beam splitter 111 for diverting a portion of the pulsed laser beam 150 to the high-speed photodetector 110, a signal generator 112 in the form of an arbitrary waveform generator (AWG), and a controller 114. The galvanometer scanner 122 also includes one or more sensors 123 in the form of one or more rotary encoders for measuring the beam steering configuration of the galvanometer beam scanner 122.

[0112] 1, the controller 114 is configured to communicate with the photodetector 110, the AWG 112, and one or more rotary encoders 123 of the galvanometer beam scanner 122. Additionally, the AWG 112 is electrically connected to the first and second beam scanner elements 130, 134 of the AOM beam scanner 120.

[0113] As described in more detail below, the arbitrary waveform generator 112 is configured to generate waveforms or signals used to control the first and second beam scanner elements 130, 134 of the AOM beam scanner 120 to steer the pulsed laser beam 150 emitted by the pulsed laser 102 according to a beam steering spatial sequence, thereby controlling the direction of the pulsed laser beam 150 on a laser pulse-by-laser pulse basis, such that at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate 108 according to a predetermined spatial sequence defining the relative spatial positions of the at least three regions of the substrate 108 and the order of irradiation of the at least three regions of the substrate 108.

[0114] In use, the apparatus 100 modifies a substrate 108 according to a method 200 shown in FIG. 2 . The substrate 108 includes at least three regions. The method 200 begins at step 202, in which the pulsed laser 102 generates a pulsed laser beam 150 comprising a train of laser pulses including at least three consecutive laser pulses. The method 200 continues at step 204, in which the illumination control mechanism 103 controls the illumination of the substrate 108 with the pulsed laser beam 150 to modify the substrate 108. Specifically, the illumination control mechanism 103 controls the direction of the pulsed laser beam 150 and / or the position of the substrate on a laser pulse-by-laser pulse basis, such that the at least three consecutive laser pulses sequentially illuminate the at least three regions of the substrate 108 according to a predetermined spatial sequence defining the relative spatial positions of the at least three regions of the substrate 108 and the order of illumination of the at least three regions of the substrate 108.

[0115] More specifically, following emission from laser 102, pulsed laser beam 150 is received by two-axis AOM beam scanner 120. A first beam scanner element 130 of two-axis AOM beam scanner 120 controls the direction of pulsed laser beam 150 in 1D by rotating pulsed laser beam 150 about the y-axis, and a second beam scanner element 134 of two-axis AOM beam scanner 120 controls the direction of pulsed laser beam 150 in 1D by rotating pulsed laser beam 150 about the x-axis.

[0116] An optical relay system 126 couples a pulsed laser beam 150 from the second beam scanner element 134 of the two-axis AOM beam scanner 120 to the galvanometer beam scanner 122 .

[0117] The galvanometer beam scanner 122 provides additional steering of the pulsed laser beam 150 in two dimensions (ie, about both the x-axis and the y-axis).

[0118] A further optical relay system 144 couples the pulsed laser beam 150 into a microscope objective 148. The microscope objective 148 focuses the pulsed laser beam 150 onto the substrate.

[0119] The irradiation control mechanism 103 moves the pulsed laser beam 150 relative to the substrate 108 by steering the pulsed laser beam 150 in two dimensions in a plane parallel to the top surface of the substrate 108 using the AOM beam scanner 120 and the galvanometer beam scanner 122. Specifically, the AOM beam scanner 120 steers the pulsed laser beam 150 to irradiate a first region with a first laser pulse, a third region with a second laser pulse, and then the second region with the third laser pulse. The galvanometer beam scanner 122 imparts additional motion to the pulsed laser beam 150 relative to the substrate 108, where the additional motion is in addition to the motion of the pulsed laser beam 150 relative to the substrate 108 imparted by the AOM beam scanner 120. For example, the galvanometer beam scanner 122 imparts additional linear motion to the pulsed laser beam 150 relative to the substrate 108.

[0120] AOM beam scanner 120 steers pulsed laser beam 150 faster than galvanometer beam scanner 122 and / or has a faster response time than galvanometer beam scanner 122. Consequently, the combined use of AOM beam scanner 120 and galvanometer beam scanner 122 allows pulsed laser beam 150 to be steered faster than is possible using galvanometer beam scanner 122 alone and over a larger area of ​​substrate 108 than is possible using AOM beam scanner 120 alone. Furthermore, by using movable stage 109 to move substrate 108 relative to pulsed laser beam 150, a larger area of ​​substrate 108 can be irradiated.

[0121] Beam splitter 111 deflects a portion of pulsed laser beam 150 onto photodetector 110, causing photodetector 110 to generate a synchronization control signal containing timing information for each pulse in pulsed laser beam 150. The synchronization control signal is electrically transmitted to controller 114. Controller 114 uses the synchronization control signal to trigger AWG 112. When triggered by the synchronization control signal, AWG 112 generates waveforms that are used to control first and second AOM beam scanner elements 130, 132 of AOM beam scanner 120 to control movement of pulsed laser beam 150 relative to substrate 108 according to a desired pulse spatial sequence.

[0122] Additionally, the one or more rotary encoders 123 generate signals representative of the beam steering configuration of the galvanometer beam scanner 122 and / or the rate of change of the beam steering configuration of the galvanometer beam scanner 122. Specifically, the one or more rotary encoders 123 generate signals representative of the one or more tilt angles of the mirrors of the galvanometer beam scanner 122 and / or the rate of change of the one or more tilt angles of the mirrors of the galvanometer beam scanner 122. The signals representative of the beam steering configuration of the galvanometer beam scanner 122 and / or the rate of change of the beam steering configuration of the galvanometer beam scanner 122 are electrically transmitted from the one or more rotary encoders 123 to the controller 114. The controller 114 then predicts the beam steering configuration of the galvanometer beam scanner 122 at the time of emission of a future laser pulse using the synchronization control signal and the signal representing the beam steering configuration of the galvanometer beam scanner 122 and / or the rate of change of the beam steering configuration of the galvanometer beam scanner 122, and the controller 114 adjusts the beam steering configuration of the galvanometer beam scanner 122 to compensate for any difference between the predicted beam steering configuration of the galvanometer beam scanner 122 and the desired future beam steering configuration of the galvanometer beam scanner 122 at the time of emission of the future laser pulse. Faster AOM beam scanner 120 Controls the rate of change of the beam steering configuration and / or beam steering configuration of the faster AOM beam scanner 120.

[0123] In this manner, the faster AOM beam scanner 120 may be used to compensate for any differences between the predicted beam steering configuration of the slower galvanometer beam scanner 122 at the time of emission of a future laser pulse and the desired future beam steering configuration of the slower galvanometer beam scanner 122, allowing each region of the substrate 108 to be irradiated with greater positional accuracy. This may improve the positional accuracy of any features created by modifying the substrate 108. This may minimize any unwanted spatial variations in the resulting modification of the substrate 108. For example, this may minimize any unwanted variations in the refractive index of the substrate 108. This may minimize any unwanted variations in the etchability of the substrate 108. This may minimize any unwanted surface roughness of the substrate 108 following subsequent chemical etching of the substrate 108 and / or when the substrate 108 is modified by removal of material from the substrate 108. As the speed of the slower galvanometer beam scanner 122 is increased, there may be an increasing difference between the measured beam steering configuration of the slower galvanometer beam scanner 122 and the intended beam steering configuration of the slower galvanometer beam scanner 122. Therefore, using the faster AOM beam scanner 120 in this manner to compensate for any difference between the beam steering configuration of the slower galvanometer beam scanner 122 and the intended beam steering configuration of the slower galvanometer beam scanner 122 may also mean that the slower galvanometer beam scanner 122 may be operated faster without unduly reducing the positional accuracy with which the pulsed laser beam 150 may irradiate each of the regions of the substrate 108, thereby increasing overall laser processing throughput.

[0124] 3 lists an example 300 of a first linear pulse spatial sequence 302, a second linear pulse spatial sequence 304, a third linear pulse spatial sequence 306, and a fourth linear pulse spatial sequence 308. In FIG. 3, different regions of the substrate 108 are arranged in a 1D uniform array along a linear path and labeled "0" through "11." Each of the linear pulse spatial sequences 302, 304, 306, and 308 specifies the sequence or order in which each of the different regions "0" through "11" of the substrate 108 is irradiated with a corresponding laser pulse.

[0125] As explained in more detail below, each linear pulse spatial sequence 302, 304, 306, 308 involves "jumping" the pulsed laser beam 150 forward along a linear path and then "jumping" the pulsed laser beam 150 backward along the linear path, so that successive laser pulses irradiate non-neighboring regions of the substrate 108. As a result, neighboring regions of the substrate 108 are irradiated with non-sequential laser pulses.

[0126] Each linear pulse spatial sequence has a duration defined as the number of laser pulses in the sequence before the sequence repeats. Furthermore, each linear pulse spatial sequence is characterized by two parameters. The first parameter is the minimum spatial jump n between successive pulses (in units of interpulse intervals). The second parameter is the minimum temporal duration m between adjacent irradiated areas of the substrate 108 in units of 1 / RR, where RR is the repetition rate of the laser pulses in the pulsed laser beam 150. To increase m or n, the duration of the linear spatial sequence must be increased.

[0127] For example, the first linear pulse spatial sequence 302 (n=2, m=2) has a period of 5 before the sequence repeats, the second linear pulse spatial sequence 304 (n=2, m=3) has a period of 7 before the sequence repeats, the third linear pulse spatial sequence 306 (n=3, m=3) has a period of 8 before the sequence repeats, and the fourth linear pulse spatial sequence 308 (n=3, m=4) has a period of 11 before the sequence repeats.

[0128] 4A shows a graph 400 illustrating the position of an area of ​​the substrate 108 irradiated by each laser pulse as a function of time according to the first linear pulse spatial sequence 302. The graph 400 corresponds to steering the pulsed laser beam 150 using the irradiation control mechanism 103 to irradiate different areas of the substrate 108 with different laser pulses along a linear path according to the first linear pulse spatial sequence 302. As a function of time, the position of the irradiated area follows a sawtooth pattern resulting from the beam steering of the faster AOM beam scanner 120 superimposed on a positive linear ramp indicated by the dashed line, where the positive linear ramp is due to the constant beam steering speed of the slower galvanometer beam scanner 122, e.g., a linear rate of change of the beam steering angle resulting from operation of the slower galvanometer scanner 122.

[0129] More specifically, according to the first linear pulse spatial sequence 302, the first pulse in the sequence is incident on region 0, the second pulse in the sequence is incident on region 2 (i.e., jumps forward past region 1), the third pulse in the sequence is incident on region 4 (i.e., jumps forward past region 3), the fourth pulse in the sequence is incident on region 1 (i.e., jumps backward to region 1), and the fifth pulse in the sequence is incident on region 3 (i.e., jumps forward past region 2). The sequence then repeats. However, because the galvanometer beam scanner 122 imparts a constant rate of movement of the pulsed laser beam 150 relative to the substrate 108, indicated by the dashed line, the sixth pulse in the sequence (i.e., the first pulse of the new sequence) is incident on region 5 (i.e., instead of region 0, as would be the case in the absence of a constant rate of movement of the pulsed laser beam 150 relative to the substrate 108). Thus, the first linear pulse spatial sequence 302 defines the illumination of different areas of the substrate 108 where successive laser pulses are not used to illuminate areas of the substrate 108 that are adjacent to each other.

[0130] FIG. 4B shows a graph 402 illustrating the contribution of the AOM beam scanner 120 of graph 400 of FIG. 4A separated from the contribution of the galvanometer beam scanner 122. Because graph 402 does not include the contribution of the galvanometer beam scanner 122, the constant velocity of movement of the pulsed laser beam 150 relative to the substrate 108 due to the slower operation of the galvanometer beam scanner 122 is not shown in FIG. 4B. Thus, graph 402 shows a periodic sawtooth pattern that repeats every iteration of the sequence. As can be seen from FIG. 4B, the periodic sawtooth pattern includes multiple teeth, where each tooth includes a gentler positive slope portion defined by multiple positions having a value that gradually increases over time, followed by a steeper negative slope portion.

[0131] Figure 5A shows a graph 500 illustrating the position of the area of ​​the substrate 108 irradiated by each laser pulse as a function of time for the laser pulse according to the second linear pulse spatial sequence 304 of Figure 3. Figure 5B shows a graph 502 illustrating the contribution of the AOM beam scanner 120 to the graph 500 of Figure 5A separated from the contribution of the galvanometer beam scanner 122.

[0132] Figure 6A shows a graph 600 illustrating the position of the area of ​​the substrate 108 irradiated by each laser pulse as a function of laser pulse time according to the third linear pulse spatial sequence 306 of Figure 3. Figure 6B shows a graph 602 illustrating the contribution of the AOM beam scanner 120 to the graph 600 of Figure 6A, separated from the contribution of the galvanometer beam scanner 122.

[0133] Figure 7A shows a graph 700 illustrating the position of the area of ​​the substrate 108 irradiated by each laser pulse as a function of laser pulse time according to the fourth linear pulse spatial sequence 308 of Figure 3. Figure 7B shows a graph 702 illustrating the contribution of the AOM beam scanner 120 to the graph 700 of Figure 7A, separated from the contribution of the galvanometer beam scanner 122.

[0134] 4A-7B, the linear pulse spatial sequence of FIG. 3 allows for the use of laser pulses with increased repetition rates, and a corresponding increase in the speed of the additional scans provided by the galvanometer beam scanner 122 along the linear path, without causing a significant change in the morphology of the induced modifications of the substrate 108. Consequently, the above-described method 200 for modifying a substrate 108 increases the laser processing throughput of the substrate 108.

[0135] 8 illustrates a first pulse spatial sequence 800 for use in the method 200 of FIG. 2 , showing the 2D positions of regions of the substrate irradiated by each laser pulse in a sequence of five laser pulses. Specifically, the first pulse spatial sequence 800 defines an irradiation order of five distinct regions of the substrate 108 using five laser pulses, where the five distinct regions are arranged along the y-direction by steering the pulsed laser beam 150 in the y-direction using the AOM beam scanner 120 and steering the pulsed laser beam 150 in the x-direction indicated by arrow 820 using the galvanometer beam scanner 122. The positions of the irradiated regions of the substrate 108 in the first pulse spatial sequence 800 are arranged as a uniform linear array having a width (i.e., along the y-direction) five times the spacing between neighboring regions. For the first pulse spatial sequence 800, n=2 and m=2.

[0136] 9 illustrates a second pulse spatial sequence 900 for use in the method 200 of FIG. 2 , showing the 2D positions of regions of the substrate 108 irradiated by each laser pulse in a sequence of 12 laser pulses. Specifically, the second pulse spatial sequence 900 defines the order of irradiation of 12 distinct regions of the substrate 108 using 12 laser pulses, where the 12 distinct regions are positioned in 2D by steering the pulsed laser beam 150 in 2D using the AOM beam scanner 120 and steering the pulsed laser beam 150 in the x-direction indicated by arrow 920 using the galvanometer beam scanner 122. The second pulse spatial sequence 900 has a width (i.e., along the y-direction) that is three times the spacing between neighboring regions. The second pulse spatial sequence 900 has a length (i.e., along the x-direction) that is four times the spacing between neighboring regions. For the second pulse spatial sequence 900, n=2 and m=2.

[0137] FIG. 10 illustrates a third pulse spatial sequence 1000 for use in the method 200 of FIG. 2 , showing the 2D positions of regions of the substrate 108 irradiated by each laser pulse in a sequence of 36 laser pulses. Specifically, the third pulse spatial sequence 1000 defines an irradiation order of 36 distinct regions of the substrate 108 using 36 laser pulses, where the 36 distinct regions are positioned in 2D by steering the pulsed laser beam 150 in 2D using the AOM beam scanner 120 and steering the pulsed laser beam 150 in the x-direction indicated by arrow 1020 using the galvanometer beam scanner 122. The third pulse spatial sequence 1000 has a width (i.e., along the y-direction) that is six times the spacing between neighboring regions. The third pulse spatial sequence 1000 has a length (i.e., along the x-direction) that is six times the spacing between neighboring regions. For the third pulse spatial sequence 1000, n=3 and m=4.

[0138] 11 illustrates a fourth pulse spatial sequence 1100 for use in the method 200 of FIG. 2 , showing the 2D locations of regions of the substrate 108 irradiated by each laser pulse in a sequence of 32 laser pulses. Specifically, the fourth pulse spatial sequence 1100 defines an irradiation order of 32 distinct regions of the substrate 108 using 32 laser pulses, where the 32 distinct regions are positioned in 2D by steering the pulsed laser beam 150 in 2D using the AOM beam scanner 120 and steering the pulsed laser beam 150 in the x-direction indicated by arrow 1120 using the galvanometer beam scanner 122. The fourth pulse spatial sequence 1100 has a width (i.e., along the y-direction) that is eight times the spacing between neighboring regions. The fourth pulse spatial sequence 1100 has a length (i.e., along the x-direction) that is four times the spacing between neighboring regions. For the fourth pulse spatial sequence 1100, n=4 and m=4.

[0139] FIG. 12 illustrates a fifth pulse spatial sequence 1200 for use in the method 200 of FIG. 2 , showing the 2D locations of regions of the substrate 109 irradiated by each laser pulse in a sequence of 18 laser pulses. Specifically, the fifth pulse spatial sequence 1200 defines an irradiation order of 18 distinct regions of the substrate 108 using 18 laser pulses, where the 18 distinct regions are positioned in 2D by steering the pulsed laser beam 150 in 2D using the AOM beam scanner 120 and steering the pulsed laser beam 150 in the x-direction indicated by arrow 1220 using the galvanometer beam scanner 122. The fifth pulse spatial sequence 1200 has a width (i.e., along the y-direction) that is nine times the spacing between neighboring regions. The fifth pulse spatial sequence 1200 has a length (i.e., along the x-direction) that is twice the spacing between neighboring regions. For the fifth pulse spatial sequence 1200, n=4 and m=3.

[0140] As can be seen from the descriptions of the spatial sequences shown in Figures 8 through 12, using the AOM beam scanner 120 and the galvanometer beam scanner 122 in combination to irradiate the substrate 108 according to the pulse spatial sequence 800, 900, 1000, 1100, 1200 can result in a substrate laser processing speed that is higher than can be achieved using the galvanometer beam scanner 122 alone, and can also result in a higher laser processing throughput of the substrate 108 compared to prior art methods for laser processing substrates.

[0141] Referring now to FIG. 13 , there is shown a schematic diagram of an alternative two-axis AOM beam scanner 1300 for use in the apparatus 100 of FIG. 1 . The alternative two-axis beam scanner 1300 is identical to the two-axis AOM beam scanner 120 described with respect to FIG. 1 , except that the first and second lenses 132, 133 are replaced with half-pitch graded-index (GRIN) rods 1324. FIG. 13 shows a first beam scanner element 130 receiving a pulsed laser beam 150 emitted by a pulsed laser 102 and deflecting (i.e., steering) the pulsed laser beam 150 into one of two deflected rays: an x+ ray 1352 and an x− ray 1353. The x+ ray 1352 is deflected by the first scanner element 130 in the positive x-direction. The x− ray 1352 is deflected by the first scanner element 130 in the negative x-direction. The x+ ray 1352 and the x- ray 1353 correspond to the rays that are maximally displaced from the optical axis 1360 of the two-axis beam scanner 1300 .

[0142] In use, the two-axis beam scanner 1300 steers the pulsed laser beam 150 along any direction between the x+ ray 1352 and the x- ray 1353. Unlike the lenses 132, 133 of the two-axis AOM beam scanner 120 described with respect to FIG. 1 , the GRIN rod 1324 is a single optical element. Because the GRIN rod 1324 is one single optical element, the GRIN rod 1324 minimizes alignment complexity. The GRIN rod 1324 reduces pulse delay variations between different optical paths through the GRIN rod 1324, which is important for processing substrates 108 using ultrafast pulsed laser beams 150. For example, a ray traveling along optical axis 1360 has a shorter optical path than x+ ray 1352, but the ray traveling along optical axis 1360 passes through a region of GRIN rod 1324 that has a higher refractive index than the region of GRIN rod 1324 through which x+ ray 1352 passes.

[0143] It should be understood that the different apparatus and methods described above are merely exemplary, and the claims are not limited to the apparatus and methods described above. Those skilled in the art will understand that various modifications can be made to the above-described apparatus and methods without departing from the scope of the appended claims. For example, although beam scanner 120 is described above as an AOM beam scanner, beam scanner 120 can be a non-mechanical beam scanner or any type of solid-state beam scanner. For example, beam scanner 120 can be an electro-optic modulator (EOM) beam scanner.

[0144] The first beam scanner element 130 of the beam scanner 120 is described above as rotating the pulsed laser beam 150 about the y-axis, and the second beam scanner element 134 of the scanner 120 is described above as rotating the pulsed laser beam 150 about the x-axis. However, in an alternative beam scanner, the first beam scanner element 130 may rotate the pulsed laser beam 150 about the x-axis, and the second beam scanner element 134 may rotate the pulsed laser beam 150 about the y-axis.

[0145] Although the further beam scanner 122 described above is a two-axis beam scanner, the further beam scanner 122 may be a one-axis beam scanner. Although the further beam scanner 122 described above is a galvanometer beam scanner, the further scanner 122 may be a tilting mirror beam scanner.

[0146] 4A-7B, the contribution of the AOM beam scanner 120 to the position of different regions of the substrate 108 irradiated by different laser pulses as a function of time is shown in FIGS. 4B, 5B, 6B, and 7B and includes a corresponding periodic sawtooth pattern including multiple teeth, where each tooth includes a more gradual positive slope portion defined by multiple positions having values ​​that gradually increase with time, followed by a steeper negative slope portion. In variations of any of the methods of modifying a substrate described with reference to FIGS. 4A-7B, the contribution of the AOM beam scanner 120 to the position of different regions of the substrate 108 irradiated by different laser pulses as a function of time may include a corresponding periodic sawtooth pattern including multiple teeth, where each tooth includes a more gradual negative slope portion defined by multiple positions having values ​​that gradually decrease with time, followed by a steeper positive slope portion.

[0147] In addition to or instead of using the faster AOM beam scanner 120 to compensate for any differences between the measured beam steering configuration of the slower galvanometer beam scanner 122 and the intended beam steering configuration of the slower galvanometer beam scanner 122, the timing of the emission of laser pulses from the pulsed laser 102 can be controlled to compensate for any differences between the measured beam steering configuration of the slower galvanometer beam scanner 122 and the intended beam steering configuration of the slower galvanometer beam scanner 122.

[0148] The method may comprise moving the substrate 108 in the direction of propagation of the pulsed laser beam 150 and / or in a direction opposite to the direction of propagation of the pulsed laser beam 150, for example using a movable stage 109. Such a method may allow the substrate 108 to be modified in 3D.

[0149] Although each region of the substrate 108 is described above as being irradiated with a single laser pulse, one or more of the regions of the substrate 108 may be irradiated with two or more non-sequential laser pulses.

[0150] Although the beam steering mechanism 104 is described above as including a photodetector 110, an AWG 112, and a controller 114, one or more of these components may be provided by the pulsed laser 102.

[0151] Although pulsed laser 102 is described above as a pulsed femtosecond laser for emitting pulsed laser beam 150 in the form of a train of laser pulses having a wavelength in the region of 1035 nm, the pulsed laser may be configured to emit a pulsed laser beam in the form of a train of laser pulses having a wavelength greater than 400 nm. For example, the pulsed laser may be configured to emit a pulsed laser beam in the form of a train of laser pulses having a wavelength substantially equal to 520 nm, 800 nm, or 1550 nm.

[0152] The train of laser pulses can be generated using a Q-switched or mode-locked laser. The train of laser pulses can be generated using a laser in combination with an optical modulator.

[0153] Each feature disclosed or described herein may be incorporated into any of the different apparatus and methods described above, either alone or in any suitable combination with any other feature disclosed or described herein. One or more of the features of any of the apparatus or methods described above with reference to the drawings may provide advantages or advantages when used separately from one or more of the other features of the same apparatus or method. Aside from the specific combinations of features of the apparatus and methods described above, different combinations of features are possible.

[0154] Those skilled in the art will appreciate that in the foregoing description and in the appended claims, terms of location such as "on," "along," and "beside" refer to conceptual illustrations such as those shown in the accompanying drawings. These terms are used for ease of reference and are not intended to be limiting in nature. Thus, these terms should be understood to refer to objects in the orientation shown in the accompanying drawings. [Item 1] 1. A method for modifying a substrate, comprising: generating a pulsed laser beam comprising a train of laser pulses, the train of laser pulses comprising at least three consecutive laser pulses; and controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that the at least three consecutive laser pulses sequentially irradiate the at least three regions of the substrate according to a predetermined spatial sequence defining relative spatial positions of the at least three regions of the substrate and an order of irradiation of the at least three regions of the substrate. A method for providing [Item 2] 2. The method of claim 1, wherein controlling the direction of the pulsed laser beam and / or the position of the substrate for each laser pulse such that the at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to the predetermined spatial sequence comprises synchronizing movement of the pulsed laser beam and / or the substrate with timing of the at least three successive laser pulses such that the at least three regions of the substrate are sequentially irradiated with the at least three successive laser pulses according to the predetermined spatial sequence. [Item 3] controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that the at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to the predetermined spatial sequence, comprises: controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate such that a first of the at least three sequential laser pulses irradiates a first region of the substrate centered at the first position; controlling movement of the pulsed laser beam and / or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a first direction from the first position on the substrate to the second position on the substrate such that a second of the at least three consecutive laser pulses irradiates a second region of the substrate centered at a second position; and controlling movement of the pulsed laser beam and / or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along the second direction from the second position on the substrate to the third position on the substrate such that a third of the at least three consecutive laser pulses irradiates a third region of the substrate centered at the third position. Including, 3. The method according to claim 1 or 2, wherein the first and second directions are different. [Item 4] Item 4. The method of item 3, wherein the third region of the substrate is located closer to the first region than the second region. [Item 5] 5. The method according to claim 3, wherein the third region of the substrate is located between the first and second regions of the substrate. [Item 6] 10. The method of any preceding item, comprising irradiating any two nearest neighboring regions of the substrate using laser pulses separated by a duration greater than or equal to a predetermined minimum duration. [Item 7] 7. The method of claim 6, wherein the predetermined minimum period is selected such that the temperature of any two nearest neighboring regions of the substrate is less than or equal to a predetermined threshold temperature. [Item 8] 10. The method of any preceding item, comprising irradiating any two regions of the substrate with successive laser pulses, wherein the any two regions of the substrate are separated by a distance greater than or equal to a predetermined minimum spatial separation. [Item 9] Item 9. The method of item 8, wherein the predetermined minimum spatial separation is selected such that the temperature of any two regions of the substrate is less than or equal to a predetermined threshold temperature. [Item 10] The method of any preceding item, wherein controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis comprises controlling movement of the pulsed laser beam relative to the substrate on a laser pulse-by-laser pulse basis, for example by steering the pulsed laser beam relative to the substrate. [Item 11] Controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis can, for example, be achieved by: in a direction parallel to the surface of the substrate; in a direction perpendicular to the surface of said substrate; in the direction of propagation of the pulsed laser beam; and / or in a direction opposite to the direction of propagation of the pulsed laser beam 10. The method of any preceding item, comprising controlling movement of the substrate relative to the pulsed laser beam by controlling movement of the substrate. [Item 12] Controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis comprises: controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate at a varying rate during a period in which at least three successive laser pulses irradiate the at least three regions of the substrate. Including, wherein the velocity includes first and second velocity components; wherein the first velocity component is constant and the second velocity component is variable; or the first velocity component varies slower than the second velocity component; The method according to any preceding item. [Item 13] Item 13. The method of item 12, wherein the first velocity component is unidirectional. [Item 14] 14. The method of claim 12 or 13, wherein the second velocity component varies in magnitude and / or direction. [Item 15] 15. The method of any one of items 12 to 14, wherein the first velocity component is associated with a movement of the substrate relative to the pulsed laser beam. [Item 16] 16. The method of any one of items 12 to 15, wherein the second velocity component is associated with movement of the pulsed laser beam relative to the substrate, for example, the second velocity component is associated with beam steering of the pulsed laser beam relative to the substrate. [Item 17] determining or measuring emission timing data for one or more of said laser pulses; determining or measuring a nominal writing position of the pulsed laser beam on the substrate and / or determining or measuring a velocity of the nominal writing position of the pulsed laser beam across the substrate; calculating a predicted nominal writing position of the pulsed laser beam at the substrate upon emission of a future laser pulse at the substrate using the determined or measured emission timing data, and at least one of the determined or measured nominal writing position of the pulsed laser beam at the substrate and the determined or measured velocity of the nominal writing position of the pulsed laser beam across the substrate; and Compensating for any difference between the predicted nominal writing position of the pulsed laser beam on the substrate and a corresponding desired future nominal writing position of the pulsed laser beam on the substrate, for example by controlling a beam steering configuration of a beam scanner and / or a rate of change of the beam steering configuration of the beam scanner; 10. The method of any preceding item, comprising: [Item 18] determining or measuring emission timing data for one or more of said laser pulses; determining or measuring a beam steering configuration, such as one or more tilt angles of a slower beam scanner, and / or determining or measuring a rate of change of a beam steering configuration, such as a rate of change of the one or more tilt angles of the slower beam scanner; calculating a predicted beam steering configuration of the slower beam scanner at the time of emission of the future laser pulse using the determined or measured emission timing data, the determined or measured beam steering configuration of the slower beam scanner, and at least one of the determined or measured rate of change of the beam steering configuration of the slower beam scanner; and using a faster beam scanner to compensate for any difference between the predicted beam steering configuration of the slower beam scanner at the time of emission of the future laser pulse and a corresponding desired beam steering configuration of the slower beam scanner, for example by controlling the beam steering configuration of the faster beam scanner and / or the rate of change of the beam steering configuration of the faster beam scanner; 17. The method of any one of items 1 to 16, comprising: [Item 19] the series of laser pulses is periodic; The train of laser pulses has a repetition rate of at least 100 KHz, at least 1 MHz, at least 2 MHz, at least 5 MHz, or at least 10 MHz; The train of laser pulses is generated using a Q-switched or mode-locked laser; and The train of laser pulses is generated using a laser in combination with an optical modulator. The method according to any preceding item, wherein at least one of [Item 20] 10. The method of any preceding item, wherein the at least three regions of the substrate are arranged in a 1D array, a 2D array, or a 3D array, such as a uniform 1D array, a uniform 2D array, or a uniform 3D array. [Item 21] sequentially irradiating the at least three regions of the substrate with the at least three successive laser pulses to modify the substrate according to a desired spatial profile; and optionally Modifying the substrate comprises: modifying the refractive index of the substrate material; Modifying the chemical etchability of the material of the substrate; or removing said material from said substrate; including at least one of The method according to any preceding item. [Item 22] 1. An apparatus for modifying a substrate, comprising: a pulsed laser for generating a pulsed laser beam comprising a train of laser pulses comprising at least three consecutive laser pulses; and an irradiation control mechanism for controlling the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that the at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to a predetermined spatial sequence defining relative spatial positions and an order of irradiation of the at least three regions of the substrate. An apparatus comprising: [Item 23] 23. The apparatus of claim 22, wherein the irradiation control mechanism is configured to control the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that the at least three successive laser pulses sequentially irradiate at least three regions of the substrate according to the predetermined spatial sequence by synchronizing movement of the pulsed laser beam and / or the substrate with timing of the at least three successive laser pulses, such that the at least three regions of the substrate are sequentially irradiated with the at least three successive laser pulses according to the predetermined spatial sequence. [Item 24] by controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate such that a first of the at least three sequential laser pulses irradiates a first region of the substrate centered at the first position; by controlling movement of the pulsed laser beam and / or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a first direction from the first position on the substrate to the second position on the substrate such that a second of the at least three sequential laser pulses irradiates a second region of the substrate centered at a second position; and by controlling movement of the pulsed laser beam and / or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a second direction from the second position on the substrate to the third position on the substrate such that a third of the at least three consecutive laser pulses irradiates a third region of the substrate centered at the third position; the irradiation control mechanism is configured to control the direction of the pulsed laser beam and / or the position of the substrate on a laser pulse-by-laser pulse basis such that the at least three consecutive laser pulses sequentially irradiate at least three regions of the substrate according to the predetermined spatial sequence; 24. The apparatus of claim 22 or 23, wherein the first and second directions are different. [Item 25] Item 25. The apparatus of item 24, wherein the third region of the substrate is located closer to the first region than the second region. [Item 26] the irradiation control mechanism includes a scanner for controlling the position of the pulsed laser beam on the substrate on a laser pulse-by-laser pulse basis, and optionally: the scanner comprises at least one of a non-mechanical scanner, a solid-state scanner, an acousto-optic modulator scanner, or an electro-optic modulator scanner, and optionally the scanner is configured to rotate a direction of the pulsed laser beam about one or two axes, such as two non-parallel axes and / or two orthogonal axes, and optionally The scanner includes a first scanner element for varying the angle of the pulsed laser beam about a corresponding first axis and a second scanner element for varying the angle of the pulsed laser beam about a corresponding second axis, wherein the first and second axes are non-parallel and / or orthogonal, and optionally: the scanner includes a first lens and a second lens arranged in a 4f configuration, the first and second lenses being separated by a distance of 2f, the first scanner element being located at a back focal plane of the first lens, and the second scanner element being located at a front focal plane of the second lens; or the scanner includes a half-pitch GRIN rod lens, wherein the first scanner element is located at a first end of the half-pitch GRIN rod lens and the second scanner element is located at a second end of the half-pitch GRIN rod lens; 26. The device according to any one of items 22 to 25,

Claims

1. a pulsed laser for generating a pulsed laser beam; a beam splitter for receiving the pulsed laser beam; an arrangement of optical elements for receiving a first portion of the pulsed laser beam from the beam splitter, the optical elements comprising: a first two-axis beam scanner element; a second two-axis beam scanner element disposed after the first two-axis beam scanner element, steering the pulsed laser beam slower than the first two-axis beam scanner element and / or having a response time slower than the response time of the first two-axis beam scanner element; and a microscope objective lens after the second two-axis beam scanner element; Includes; a stage for receiving a substrate, the stage being positioned such that a substrate coupled to the stage receives a pulsed laser beam from the arrangement of optical elements; a photodetector for receiving a second portion of the pulsed laser beam; and a controller for controlling the beam steering configuration of the first two-axis beam scanner element and / or the rate of change of the beam steering configuration of the first two-axis beam scanner element using a signal from the photodetector and the beam steering configuration of the second two-axis beam scanner element and / or the rate of change of the beam steering configuration of the second two-axis beam scanner element. A system comprising:

2. 2. The system of claim 1, wherein the controller operates the first two-axis beam scanner element to control the direction of the pulsed laser beam on a laser pulse-by-laser pulse basis, such that at least three consecutive laser pulses sequentially irradiate the at least three regions of the substrate according to a predetermined spatial sequence that defines the relative spatial positions and order of irradiation of the at least three regions of the substrate.

3. 3. The system of claim 1, wherein the controller controls the pulsed laser such that at least three successive laser pulses sequentially irradiate the at least three regions of the substrate according to a predetermined spatial sequence that defines the relative spatial positions and order of irradiation of the at least three regions of the substrate.

4. An irradiation control mechanism including the beam splitter, the optical element, the photodetector, and the controller, The illumination control mechanism comprises: controlling a direction of the pulsed laser beam or a position of the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate, such that a first of at least three successive laser pulses irradiates a first region of the substrate centered at the first position; controlling a direction of the pulsed laser beam or a position of the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a first direction from the first position on the substrate to a second position on the substrate, such that a second of the at least three consecutive laser pulses irradiates a second region of the substrate centered at the second position; and controlling a direction of the pulsed laser beam or a position of the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a second direction from the second position on the substrate to a third position on the substrate, such that a third of the at least three consecutive laser pulses irradiates a third region of the substrate centered at the third position, wherein the first direction and the second direction are different; 3. The system according to claim 1 or 2.

5. 3. The system of claim 1, wherein the first two-axis beam scanner element is a two-axis acousto-optic modulator (AOM) beam scanner element including a first one-axis AOM beam scanner element for controlling the direction of the pulsed laser beam in a first direction and a second one-axis AOM beam scanner element for controlling the direction of the pulsed laser beam in a second direction.

6. The system of claim 5 , wherein the first direction and the second direction are orthogonal.

7. 6. The system of claim 5, further comprising a first lens and a second lens between the first one-axis AOM beam scanner element and the second one-axis AOM beam scanner element, wherein the first lens is separated from the first one-axis AOM beam scanner element by a focal length f, the second lens is separated from the first lens by a focal length 2f, and the second one-axis AOM beam scanner element is separated from the second lens by a focal length f.

8. The system of claim 1 or 2, wherein the arrangement of optical elements further comprises a first lens and a second lens between the first two-axis beam scanner element and the second two-axis beam scanner element.

9. 9. The system of claim 8, wherein the first lens is spaced a focal length f from the first two-axis beam scanner element, the second lens is spaced a focal length 2f from the first lens, and the second two-axis beam scanner element is spaced a focal length f from the second lens.

10. The system of claim 1 or 2, wherein the second two-axis beam scanner element is a two-axis galvanometer beam scanner.

11. The system of claim 1 or 2, wherein the arrangement of optical elements further comprises an optical relay system between the second two-axis beam scanner element and the microscope objective lens.

12. 12. The system of claim 11, wherein the optical relay system includes a first lens spaced a focal length f from the second two-axis beam scanner element, a second lens spaced a focal length 2f from the first lens, and the microscope objective lens spaced a focal length f from the second lens.

13. 3. The system of claim 1 or 2, wherein the pulsed laser generates a train of periodic laser pulses at a repetition rate of at least 100 KHz.

14. The system of claim 1 or 2, wherein the pulsed laser comprises a Q-switched laser or a mode-locked laser.

15. 3. The system of claim 1, wherein the controller uses the signal from the photodetector and the beam steering configuration of the second two-axis beam scanner element and / or the rate of change of the beam steering configuration of the second two-axis beam scanner element to predict a beam steering configuration of the second two-axis beam scanner element at a future laser pulse emission, and controls the beam steering configuration of the first two-axis beam scanner element and / or the rate of change of the beam steering configuration of the first two-axis beam scanner element to compensate for any difference between the predicted beam steering configuration of the second two-axis beam scanner element and a corresponding desired beam steering configuration of the second two-axis beam scanner element at the future laser pulse emission.

16. generating a pulsed laser beam; receiving the pulsed laser beam with a beam splitter; receiving a first portion of the pulsed laser beam from the beam splitter with an arrangement of optical elements, the optical elements comprising: a first two-axis beam scanner element; a second two-axis beam scanner element disposed after the first two-axis beam scanner element, steering the pulsed laser beam slower than the first two-axis beam scanner element and / or having a response time slower than the response time of the first two-axis beam scanner element; and a microscope objective lens after the second two-axis beam scanner element; Including; positioning the stage such that a substrate coupled to the stage receives the pulsed laser beam from the arrangement of optical elements; receiving a second portion of the pulsed laser beam with a photodetector; and controlling the beam steering configuration of the first two-axis beam scanner element and / or the rate of change of the beam steering configuration of the first two-axis beam scanner element using a signal from the photodetector and the beam steering configuration of the second two-axis beam scanner element and / or the rate of change of the beam steering configuration of the second two-axis beam scanner element; A method comprising:

17. generating the pulsed laser beam comprises generating the pulsed laser beam comprising a train of laser pulses, the train of laser pulses comprising at least three consecutive laser pulses; The method comprises: sequentially irradiating at least three regions of the substrate with the at least three consecutive laser pulses to modify the substrate according to a desired spatial profile, wherein modifying the substrate includes at least one of modifying a refractive index of a material of the substrate, modifying a chemical etchability of the material of the substrate, or removing the material of the substrate; and controlling the direction of the pulsed laser beam or the direction of the pulsed laser beam and the position of the substrate for each laser pulse, such that the at least three consecutive laser pulses sequentially irradiate the at least three regions of the substrate according to a predetermined spatial sequence that defines relative spatial positions of the at least three regions of the substrate and an order of irradiation of the at least three regions of the substrate. The method of claim 16 further comprising:

18. 18. The method of claim 17, wherein controlling the direction of the pulsed laser beam or the direction of the pulsed laser beam and the position of the substrate comprises synchronizing movement of the pulsed laser beam and / or the substrate with timing of the at least three consecutive laser pulses, such that the at least three regions of the substrate are sequentially irradiated with the at least three consecutive laser pulses according to the predetermined spatial sequence.

19. Controlling the direction of the pulsed laser beam or the direction of the pulsed laser beam and the position of the substrate comprises: controlling movement of the pulsed laser beam or the substrate to move a nominal writing position of the pulsed laser beam to a first position on the substrate, such that a first of the at least three consecutive laser pulses irradiates a first region of the substrate centered at the first position; controlling movement of the pulsed laser beam or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a first direction from the first position on the substrate to a second position on the substrate, such that a second of the at least three consecutive laser pulses irradiates a second region of the substrate centered at the second position; and controlling movement of the pulsed laser beam or the substrate to move the nominal writing position of the pulsed laser beam across the substrate along a second direction from the second position on the substrate to a third position on the substrate, such that a third of the at least three consecutive laser pulses irradiates a third region of the substrate centered at the third position, wherein the first direction and the second direction are different; 19. The method of claim 17 or 18, comprising:

20. 19. A method according to claim 17 or 18, comprising irradiating any two nearest neighboring regions of the substrate using laser pulses separated by a period greater than or equal to a predetermined minimum period, wherein the predetermined minimum period is selected such that the temperature of any two nearest neighboring regions of the substrate is less than or equal to a predetermined threshold temperature.

21. 19. A method according to claim 17 or 18, comprising irradiating any two regions of the substrate with successive laser pulses, wherein the any two regions of the substrate are separated by a distance greater than or equal to a predetermined minimum spatial separation, wherein the predetermined minimum spatial separation is selected such that the temperature of the any two regions of the substrate is less than or equal to a predetermined threshold temperature.

22. controlling the direction of the pulsed laser beam or the direction of the pulsed laser beam and the position of the substrate on a laser pulse-by-laser pulse basis comprises controlling movement of the pulsed laser beam and / or the substrate to move a nominal writing position of the pulsed laser beam across the substrate at a rate that varies during a period in which the at least three successive laser pulses irradiate the at least three regions of the substrate; wherein the velocity comprises a first velocity component and a second velocity component, wherein the first velocity component is constant and the second velocity component is variable; or wherein the first velocity component varies slower than the second velocity component.

19. The method of claim 17 or 18.

23. 23. The method of claim 22, wherein the first velocity component is unidirectional and the second velocity component varies in magnitude and / or direction.

24. 23. The method of claim 22, wherein the first velocity component is associated with movement of the substrate relative to the pulsed laser beam.

25. determining or measuring emission timing data for one or more of the laser pulses; determining or measuring a nominal writing position of the pulsed laser beam on the substrate and / or determining or measuring a velocity of the nominal writing position of the pulsed laser beam across the substrate; calculating a predicted nominal writing position of the pulsed laser beam on the substrate upon emission of a future laser pulse on the substrate using the determined or measured emission timing data, the determined or measured nominal writing position of the pulsed laser beam on the substrate, and at least one of the determined or measured velocity of the nominal writing position of the pulsed laser beam across the substrate; and compensating for any difference between the predicted nominal writing position of the pulsed laser beam at the substrate and the corresponding desired future nominal writing position of the pulsed laser beam at the substrate by controlling a beam steering configuration of the first two-axis beam scanner element and / or a rate of change of the beam steering configuration of the first two-axis beam scanner element to compensate for any difference between the predicted nominal writing position of the pulsed laser beam at the substrate and the corresponding desired future nominal writing position of the pulsed laser beam at the substrate.

19. The method of claim 17 or 18, comprising:

26. determining or measuring emission timing data for one or more of the laser pulses; determining or measuring a beam steering configuration of the second two-axis beam scanner element including one or more tilt angles and / or determining or measuring a rate of change of the beam steering configuration of the second two-axis beam scanner element including a rate of change of the one or more tilt angles; calculating a predicted beam steering configuration of the second two-axis beam scanner element at the time of emission of a future laser pulse using the determined or measured emission timing data and at least one of the determined or measured beam steering configuration of the second two-axis beam scanner element and the determined or measured rate of change of the beam steering configuration of the second two-axis beam scanner element; and using the first two-axis beam scanner element to control a beam steering configuration of the first two-axis beam scanner element and / or a rate of change of the beam steering configuration of the first two-axis beam scanner element to compensate for any difference between the predicted beam steering configuration of the second two-axis beam scanner element and a corresponding desired beam steering configuration of the second two-axis beam scanner element at the time of emission of the future laser pulse.

19. The method of claim 17 or 18, comprising:

27. 19. The method of claim 17 or 18, wherein the at least three regions of the substrate are arranged in a 1D, 2D or 3D array, or in a uniform 1D, 2D or 3D array.

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