Ablation method and analysis method

Abstract

An ablation method according to one aspect of the present disclosure comprises: determining a plurality of regions for an object to be irradiated with pulse laser light; and sequentially or alternately irradiating the plurality of regions having been determined with pulse laser light having a preset number of pulses.

Description

Ablation and Analysis Methods

[0001] The present disclosure relates to ablation and analysis methods.

[0002] An analytical unit that irradiates a target object with a laser beam and analyzes the elements contained in the target object is known. One such analytical unit is an analytical device that includes a laser ablation device that includes a laser beam emitted from a laser light source and an optical system that reflects the laser beam toward the target object, and an analyzer that performs analysis using an inductively coupled plasma method (see JP 2021-173553 A).

[0003] Japanese Patent Application Laid-Open No. 2021-173553

[0004] In the analytical device described in Patent Document 1, a laser ablation device irradiates a laser beam onto a sample contained in a cell, and the aerosol generated from the sample by the laser beam irradiation is transported to an analyzer for analysis. In the analysis, it may be necessary to ablate multiple regions of the sample, or one or multiple regions of multiple samples, and mix the generated aerosols for analysis.

[0005] In view of the above circumstances, the present disclosure aims to provide an ablation method that can ablate multiple regions of a target object and easily adjust the mixing ratio of the generated aerosol to a desired ratio.

[0006] An ablation method according to one aspect of the present disclosure, which has been made to solve the above problem, includes the steps of determining multiple regions on an object to be irradiated with pulsed laser light, and sequentially or alternately irradiating the determined multiple regions with pulsed laser light of a set number of pulses.

[0007] An ablation method according to one aspect of the present disclosure can ablate multiple regions of a target object and can produce aerosols with any mixing ratio.

[0008] Fig. 1 is a schematic side view showing a state in which a pulsed laser beam of an ablation unit used in an ablation method according to an embodiment of the present disclosure passes through an objective lens. Fig. 2 is a schematic side view showing a state in which a pulsed laser beam of the ablation unit of Fig. 1 passes through an fθ lens. Fig. 3 is a schematic side view showing a state in which a pulsed laser beam of the ablation unit of Fig. 1 passes through an fθ lens in a manner different from that of Fig. 2.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) An ablation method according to one aspect of the present disclosure includes a step of determining multiple regions on one or more objects to be irradiated with pulsed laser light, and a step of sequentially or alternately irradiating the determined multiple regions with pulsed laser light of a set number of pulses.

[0011] In this ablation method, a set number of pulses of pulsed laser light is irradiated onto multiple regions (irradiation regions) of one or multiple objects, and the number of ablation events in each irradiation region can be varied depending on the set number of pulses. This allows the amount of aerosol generated in each irradiation region to be controlled, and the mixing ratio of the aerosols can be set to a desired ratio.

[0012] (2) In the above (1), the determining step may determine a plurality of regions in one object. That is, the ablation method is suitable for ablating a plurality of regions in one object.

[0013] (3) In the above (1), the determining step may determine one or more regions in each of a plurality of objects. That is, the ablation method is also suitable for ablating one or more regions in each of a plurality of objects.

[0014] (4) In any one of (1) to (3), the repetition frequency of the pulsed laser light may be 1 kHz or more. By setting the repetition frequency to 1 kHz or more, it is possible to increase the speed at which the target object is ablated.

[0015] (5) In any of (1) to (4), the set number of pulses may be 1. By irradiating each of the determined regions with the pulsed laser light for one pulse at a time, it is possible to suppress the time difference in aerosol generation and make the mixture ratio approximately uniform.

[0016] (6) An ablation method according to another aspect of the present disclosure includes a step of determining one area on each of two objects to be irradiated with pulsed laser light, and a step of irradiating each of the determined areas with pulsed laser light alternately, one pulse at a time.

[0017] In this ablation method, one pulse of pulsed laser light is irradiated onto one irradiation area on each of two objects, thereby making it possible to substantially equalize the mixing ratio while suppressing the time difference in aerosol generation in each irradiation area.

[0018] (7) An analysis method according to another aspect of the present disclosure includes the steps of ablating an object using any of the ablation methods (1) to (6) above, transporting the aerosol generated by the ablation to an analysis unit, and analyzing the transported aerosol in the analysis unit.

[0019] Since the analysis method analyzes the aerosol generated by the ablation method, analysis of the mixed aerosol can be easily performed.

[0020] It should be noted that the region includes points (caused by one ablation) and lines (continuous straight lines, curved lines, and combinations thereof caused by multiple ablations).

[0021] [Details of the embodiment of the present disclosure] Hereinafter, the embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the drawings are illustrative of the embodiment, and the shape, size, scale, arrangement, etc. of each component (member) may differ from the actual ones.

[0022] <First embodiment> The analysis method includes a step of ablating an object using the ablation method, a step of transporting an aerosol generated by the ablation to an analysis unit, and a step of analyzing the transported aerosol in the analysis unit.

[0023] [Ablation Method] This ablation method includes the steps of determining a plurality of regions on one or a plurality of objects to be irradiated with pulsed laser light, and sequentially or alternately irradiating the determined regions with pulsed laser light of a set number of pulses. The object is not particularly limited and may be a solid or a liquid, but this ablation method is particularly suitable for solid objects.

[0024] The ablation method can be performed using, for example, an ablation unit 100 shown in Figures 1, 2, and 3. The ablation unit 100 is connected to, for example, an analysis unit 200 that performs elemental analysis, and analyzes the elements contained in a target object (not shown).

[0025] [Analysis Unit] The analysis unit 200 is not particularly limited, and may be, for example, a device that performs a known analysis method such as inductively coupled plasma mass spectrometry or high frequency inductively coupled plasma atomic emission spectrometry.

[0026] [Ablation Unit] Ablation unit 100 mainly includes a laser emission unit 110 that emits pulsed laser light L (shown by a dashed line in each drawing), a light reflection unit that reflects pulsed laser light L (hereinafter also referred to as laser light L) to an arbitrary position, and a stage 180 on which a cell 170 that contains an object to be treated (not shown) is placed. Ablation unit 100 of this embodiment also includes an image processing unit 190 that includes cameras 191, 192, and 193 that capture images of the object to be treated and a monitor 195 that displays images from cameras 191, 192, and 193, and a light reflection control unit 196 that controls the light reflection unit so that laser light L is irradiated onto an irradiation area.

[0027] (Cell) The target object is housed in a cell 170 and irradiated with the laser light L. The cell 170 is a container that houses one or more target objects and prevents the aerosol generated by ablation from scattering. A transparent plate (not shown) through which the laser light L is incident is disposed on the top surface of the cell 170. That is, the cell 170 has a light incident portion formed of a transparent plate on the incident surface of the laser light L.

[0028] The cell 170 has a gas supply port 171 through which a carrier gas that transports the aerosol to the analysis unit 200 is supplied, and a gas exhaust port 172 through which the carrier gas containing the aerosol is exhausted. A gas supply pipe P1 is connected to the gas supply port 171, and a gas exhaust pipe P2 is connected to the gas exhaust port 172.

[0029] The surface of the object contained in the cell 170 is irradiated with laser light L to ablate it, thereby partially aerosolizing the object. Specifically, the surface of the object is vaporized by irradiation with laser light L, and a portion of the vaporized material is ionized. The laser light L then penetrates the object to a depth of several nanometers to several micrometers from the surface and releases most of its energy, vaporizing and fragmenting the object's constituent components. This ablation releases the ionized and vaporized elements, some of which recondense into solid particles, and fragmented fragments from the object as an aerosol. The aerosol is transported to the analysis unit 200 via the gas exhaust pipe P2 by a carrier gas, such as helium, supplied into the cell 170, where the chemical composition of the object is analyzed.

[0030] (Stage) The cell 170 is placed on the stage 180. Specifically, the cell 170 containing the object is placed on the mounting surface (top surface) of the stage 180 so as not to move relative to the stage 180.

[0031] The means for preventing the cell 170 from moving relative to the stage 180 is not particularly limited, and may be fixed with bolts, pins, or the like, but is preferably fixed by magnetic force. Specifically, it is preferable that a magnet (not shown) is placed on the stage 180, and the cell 170, which is made of a magnetic material such as metal, is fixed by the magnetic force of the magnet. A coil (not shown) that generates a magnetic force when energized may also be placed on the stage 180. The magnet or the coil may be placed on the cell 170, or may be placed on both the stage 180 and the cell 170. It is preferable that a guide portion (not shown) is provided on the mounting surface of the stage 180 to determine the position at which the cell 170 is placed.

[0032] The stage 180 is preferably capable of moving the cell 170 in the axial direction (Z direction) of the laser light L incident on the object, and in two directions (X direction and Y direction) that are perpendicular to this axial direction and perpendicular to each other. In other words, it is preferable that the mounting surface of the stage 180 is movable in the X-Y-Z directions. This makes it possible to easily adjust the irradiation position of the laser light L on the object in the X-, Y-, and Z-directions.

[0033] The Z-direction movement means (height adjustment means) on the mounting surface of the stage 180 is not particularly limited, but is preferably configured to be adjustable by piezoelectric element drive. The upper limit of the minimum movement unit (resolution) for the Z-direction movement is preferably 5 nm, more preferably 2 nm, and even more preferably 1 nm. The lower limit of the minimum movement unit is not particularly limited and may be, for example, 0.1 nm. By setting the minimum movement unit within the above range, the focusing position of the laser light L in the Z direction can be efficiently determined. In other words, the focus of the fθ lens 130 and the objective lens 140, the depth to which the laser light L penetrates the object, and the like can be adjusted with high precision, resulting in efficient aerosolization and improved analysis accuracy by the analysis unit 200. The stage 180 may be a goniostage capable of changing the angle in the X-Y plane.

[0034] (Laser Emitter) The laser emitter 110 emits laser light L to irradiate the surface of the target object (hereinafter also referred to as the target surface). The laser emitter 110 includes a known laser oscillator (not shown), such as a solid-state laser, a semiconductor laser, or a gas laser. The wavelength range of the laser light L can preferably be set arbitrarily. The wavelength of the laser light L is preferably deep ultraviolet. That is, the laser emitter 110 can preferably set the wavelength range of the laser light L to deep ultraviolet. Specifically, the wavelength of the laser light L can preferably be set to 280 nm or less, more preferably 270 nm or less, and even more preferably 260 nm or less. The lower limit of the wavelength that can be set is not particularly limited and may be, for example, 100 nm. Irradiating the target surface with laser light L having a deep ultraviolet wavelength can promote the reduction of aerosol (fragments) by ablation.

[0035] It is preferable that the pulse width of the pulse wave of the laser light L emitted from the laser emission unit 110 can be set arbitrarily. The pulse width can be set preferably to 600 femtoseconds or less, and more preferably to 300 femtoseconds or less. By irradiating the target surface with laser light L having such a pulse width, it is possible to further promote the aerosolization by ablation.

[0036] By setting the wavelength and pulse width of the laser light L within the above ranges, the absorption efficiency of the energy of the laser light L (laser energy) on the target surface is improved, and if the target object is a solid object, the depth to which the laser light L penetrates into the surface (surface layer) of the target object is reduced. In other words, the laser energy can be absorbed in a small volume.

[0037] When a solid object is analyzed (e.g., for the analysis of contained elements), irradiating the solid object with laser light L having a deep ultraviolet wavelength and a short pulse of 600 femtoseconds or less improves the absorption efficiency of laser energy on the surface of the solid object, thereby reducing the depth of the ablation marks. Specifically, the depth of the ablation marks can be controlled in nanometer units. By reducing the depth of the ablation marks, accurate analysis of the depth direction of the solid object can be performed. In other words, a precise depth profile of the solid object can be obtained. Note that the ablation marks (also called spots, craters, etc.) refer to grooves (holes) formed in a solid object by ablation with laser light.

[0038] Furthermore, efficient absorption of laser energy by the surface of the solid object promotes the fragmentation of fragments broken up at the surface, improving aerosolization and ultimately improving the analytical accuracy by the analysis unit 200. Specifically, the average particle size of the fragments broken up at the surface can be set to 400 nm or less, or 300 nm or less, or 200 nm or less. This promotes ionization of the fragments by plasma in the analysis unit 200, improving the analytical accuracy. The average particle size means the particle size at 50% of the integrated value in the particle size distribution determined by the laser diffraction scattering method.

[0039] The repetition frequency of the pulse wave of the laser light L can be set arbitrarily. The repetition frequency can be set to 1 kHz or more, more preferably 10 kHz or more, and even more preferably 100 kHz or more. By setting such a repetition frequency, ablation of the determined multiple irradiation regions can be performed at high speed.

[0040] (Lens) The ablation unit 100 has a lens that adjusts the focused diameter of the laser light L on the target surface. The ablation unit 100 of this embodiment includes an fθ lens 130 and an objective lens 140 so that the focused diameter of the laser light L can be selected arbitrarily. In the laser ablation unit 100 of this embodiment, the fθ lens 130 and the objective lens 140 are arranged parallel to each other in the X direction. The fθ lens 130 focuses the laser light L on the surface of the target object with a relatively large focused diameter, while the objective lens 140 focuses the laser light L with a smaller focused diameter than the fθ lens 130. A beam expander lens (not shown) that expands the beam diameter may be arranged upstream of the fθ lens 130 and the objective lens 140.

[0041] The objective lens 140 of this embodiment includes three objective lenses 141, 142, and 143. The three objective lenses 141, 142, and 143 are held in parallel in the X direction by a lens holder 144. The lens holder 144 is mounted on an objective lens moving means (not shown), such as a known one-axis stage, and can move in the X direction. By moving the lens holder 144, the ablation unit 100 can arbitrarily select one of the three objective lenses 141, 142, and 143 to vary the focused diameter of the laser light L on the target surface.

[0042] The focused diameter of the laser light L by at least one objective lens 140 is preferably 2 μm or less. That is, it is preferable that any one of the three objective lenses 141, 142, and 143 has a magnification that can make the focused diameter of the laser light L on the target surface 2 μm or less. The upper limit of the focused diameter at the above magnification is more preferably 1.5 μm, even more preferably 1.0 μm, and particularly preferably 0.5 μm. By irradiating the target surface with the laser light L at such a focused diameter, precise ablation can be performed. The lower limit of the focused diameter at the above magnification is not particularly limited and may be, for example, 0.1 μm.

[0043] Specifically, it is preferable to select the lens magnification so that the focused light diameter is 0.5 μm for the first objective lens 141, 3.0 μm for the second objective lens 142, and 5.0 μm for the third objective lens 143. The lens magnifications of the three objective lenses 141, 142, and 143 may be, for example, 60x, 40x, 20x, or 50x, 20x, 10x, etc. The focused light diameter of the fθ lens 130 may be, for example, 10 μm. In this way, the focused light diameter on the target surface can be arbitrarily selected using multiple lenses, allowing ablation to be performed according to the purpose of analysis, the characteristics of the target object, etc.

[0044] (Light Reflecting Unit) The light reflecting unit reflects the laser light L so that the laser light L irradiates a desired position on the target surface. That is, the light reflecting unit controls the irradiation position of the laser light L on the target surface. The light reflecting unit is not particularly limited, but is preferably galvano units 121 and 122 including a galvanometer mirror. The ablation unit 100 of this embodiment has a first galvano unit 121 that controls the irradiation position of the laser light L passing through the objective lens 140, and a second galvano unit 122 that controls the irradiation position of the laser light L passing through the fθ lens 130. By using such galvano units 121 and 122, the laser light L passing through the fθ lens 130 and the objective lens 140 can be moved to a desired position on the target surface, making it easy to ablate a desired area of ​​the target surface.

[0045] The first galvanometer unit 121 has a first galvanometer mirror 121a and a second galvanometer mirror 121b. Each of the two galvanometer mirrors 121a and 121b has a driver (not shown) that changes the reflection angle by being rotated. That is, the first galvanometer unit 121 has two drivers. Each of these two drivers is electrically connected to the light reflection control unit 196. The first galvanometer mirror 121a reflects the laser light L emitted by the laser emission unit 110 and moves the irradiation position in one direction (X direction). The second galvanometer mirror 121b reflects the laser light L reflected by the first galvanometer mirror 121a and moves the irradiation position in a direction (Y direction) perpendicular to the one direction.

[0046] Similar to the first galvano unit 121, the second galvano unit 122 has a third galvano mirror 122a that moves the irradiation position of the laser light L that passes through the fθ lens 130 in the X direction, and a fourth galvano mirror 122b that moves the irradiation position of the laser light L reflected by the third reflecting mirror 122a in the Y direction. The second galvano unit 122 has two drive units (not shown) that change the reflection angle by rotationally driving the two galvano mirrors 122a and 122b, respectively, and each of the two drive units is electrically connected to the light reflection control unit 196.

[0047] It is preferable that the galvanometer units 121 and 122 can change the reflection angle in accordance with the repetition frequency of the laser light L. That is, it is preferable that the first galvanometer mirror 121a and the second galvanometer mirror 121b and the third galvanometer mirror 122a and the fourth galvanometer mirror 122b can change the reflection angle in synchronization with the repetition frequency of the laser light L. This makes it possible to increase the speed of the laser light L scanning the target surface. Furthermore, it is possible to sequentially or alternately irradiate multiple regions of the target object or respective regions of multiple target objects contained in the cell 170 with the laser light L at high speed.

[0048] The ablation unit 100 of this embodiment has an objective lens reflecting mirror 151 that reflects the laser light L reflected by the first galvano section 121, and an fθ lens reflecting mirror 152 that reflects the laser light L reflected by the second galvano section 122. The objective lens reflecting mirror 151 reflects the laser light L toward the objective lens 140. The fθ lens reflecting mirror 152 reflects the laser light L toward the fθ lens 130.

[0049] The objective lens reflecting mirror 151 is preferably a dichroic mirror. The dichroic mirror reflects the laser light L reflected by the first galvano unit 121 toward the objective lens 140 and transmits other light. By using a dichroic mirror as the objective lens reflecting mirror 151, it is possible to easily position the first camera 191 so as to face the entrance surface of the cell 170, as will be described later.

[0050] (Switching means) The ablation unit 100 of this embodiment has a first laser reflecting mirror 161 that reflects laser light L toward the first galvano section 121, a second laser reflecting mirror 162 that reflects laser light L toward the second galvano section 122, and a third laser reflecting mirror 163 that reflects laser light L emitted from the laser emitting section 110 toward the first laser reflecting mirror 161 and the second laser reflecting mirror 162.

[0051] The second laser reflecting mirror 162 is disposed on the optical axis of the laser light L reflected by the third laser reflecting mirror 163. The first laser reflecting mirror 161 is configured to move between on the optical axis of the laser light L reflected by the third laser reflecting mirror 163 and outside the optical axis. That is, the first laser reflecting mirror 161 moves between a position where it reflects the laser light L reflected by the third laser reflecting mirror 163 and a position where it does not reflect the laser light L. When the first laser reflecting mirror 161 moves to a position where it reflects the laser light L reflected by the third laser reflecting mirror 163 toward the first galvano unit, the laser light L passes through the objective lens 140. When the first laser reflecting mirror 161 moves to a position where it does not reflect the laser light L reflected by the third laser reflecting mirror 163, the laser light L is reflected by the second laser reflecting mirror 162 and passes through the fθ lens 130. That is, the first laser reflecting mirror 161 is configured as a means for switching the optical path of the laser light L. The ablation unit 100 can selectively ablate the object using laser light L that has passed through the fθ lens 130 and ablate the object using laser light L that has passed through the objective lens 140 by switching the optical path through the movement of the first laser reflector 161.

[0052] The means by which the first laser reflecting mirror 161 moves between a position where it reflects the laser light L reflected by the third laser reflecting mirror 163 and a position where it does not reflect the laser light L is not particularly limited. For example, as shown in FIG. 2, the first laser reflecting mirror 161 may be configured to move in the X direction, or as shown in FIG. 3, the first laser reflecting mirror 161 may be rotated so that the third laser reflecting mirror 163 moves away from the optical axis of the reflected laser light L.

[0053] The stage 180 can move between a first position (see FIG. 1 ) where the object is ablated by the objective lens 140 and a second position (see FIG. 2 ) where the object is ablated by the fθ lens 130. That is, the ablation unit 100 has a stage moving means (not shown) that moves the stage 180 between the first position and the second position. The stage moving means is not particularly limited, and the stage 180 may be disposed on a known one-axis stage, for example.

[0054] It is preferable that the switching means and the stage moving means are configured to operate in synchronization with each other. That is, when the first laser reflecting mirror 161 moves to a position where it reflects the laser light L toward the first galvano unit 121, the stage 180 is moved to the first position (on the optical axis of the laser light L reflected by the objective lens reflecting mirror 151) by the stage moving means, and when the first laser reflecting mirror 161 moves to a position where it does not reflect the laser light L toward the first galvano unit, the stage 180 is moved to the second position (on the optical axis of the laser light L reflected by the fθ lens reflecting mirror 152) by the stage moving means.

[0055] (Image Processing Unit) The ablation unit 100 includes an image processing unit 190 including cameras 191, 192, and 193 that capture images of the target object and a monitor 195 that displays images from the cameras 191, 192, and 193. In this embodiment, the image processing unit 190 includes a first camera 191 that captures images of the target object to be ablated by the objective lens 140, a second camera 192 and a third camera 193 as fθ lens cameras that capture images of the target object to be ablated by the fθ lens 130, and a monitor 195 that displays images captured by these cameras 191, 192, and 193. The monitor 195 may be, for example, a display screen of a personal computer. The monitor 195 may be a device (e.g., a touch panel) that allows input by touching the screen. Preferably, the operator can determine the area to be irradiated with the laser light L by touching any portion of the target surface displayed on the monitor 195.

[0056] The first camera 191 and the objective lens 140 are preferably disposed on the axis of the laser light L incident on the object. In other words, the first camera 191 is preferably disposed in the axial direction of the laser light L incident on the object so as to face the incident surface of the cell 170 across the objective lens 140. The first camera 191 in this embodiment is disposed above the objective lens reflector 151 (the side opposite to where the laser light L is reflected) on an extension of the optical axis of the laser light L passing through the objective lens 140. This allows the image captured by the first camera 191 from the normal direction of the object surface to be displayed on the monitor 195, thereby improving the accuracy of the determined area.

[0057] The second camera 192 may be disposed at an angle with respect to the optical axis of the laser light L passing through the fθ lens 130. In other words, the second camera 192 may be disposed so as to capture an image of the object housed in the cell 170 from an oblique angle.

[0058] The second camera 192 is a camera for determining the position of an object to be irradiated with the laser light L transmitted through the fθ lens 130. That is, the operator determines the position of the object while checking the image captured by the second camera 192 on the monitor 195.

[0059] The third camera 193 is a camera that enlarges and captures an image of the target surface positioned by the second camera 192. The worker determines the irradiation area of ​​the target object while checking the image captured by the third camera 193 on the monitor 195. The third camera 193 captures an image that is enlarged compared to that captured by the second camera 192. In other words, the third camera 193 enlarges and captures a part of the area captured by the second camera 192.

[0060] The third camera 193 is disposed between the fθ lens 130 and the cell 170 so that the imaging direction (the direction in which the third camera 193 captures the subject) is perpendicular to the optical axis of the laser light L that irradiates the object. A periscope 194 for reflecting the object to be imaged at approximately 90° is disposed in the imaging direction of the third camera 193. That is, the third camera 193 images the object via the periscope 194, which changes the position (direction) of the viewpoint by approximately 90°.

[0061] The periscope 194 includes a reflecting mirror, a prism, a lens, etc. The periscope 194 preferably includes a telecentric lens. The periscope 194 is disposed so as to be movable in the image capturing direction (X direction) of the third camera 193. The means for moving the periscope 194 in the X direction is not particularly limited, and for example, the periscope 194 may be equipped with a drive source (such as a motor), the periscope 194 may be disposed on a one-axis stage, or the periscope 194 may be manually operated by an operator.

[0062] The operator positions the target object while checking the image captured by the second camera 192 and moves the periscope 194 so that the target object can be imaged by the third camera 193. Next, the operator determines the irradiation area on the monitor 195 while checking the image captured by the third camera 193 via the periscope 194 (see FIG. 3 ). After determining the irradiation area, the operator moves the periscope 194 so that it is positioned outside the optical axis of the laser light L, and begins irradiation with the laser light L (see FIG. 2 ). This arrangement facilitates positioning of the target object and improves the accuracy of determining the irradiation area of ​​the target object to be ablated by the f-theta lens 130. Note that FIG. 3 also illustrates, for reference, the laser light L passing through the f-theta lens 130 and the periscope 194 moved onto its optical axis.

[0063] (Light Reflection Control Unit) The light reflection control unit 196 controls the light reflection unit so that the determined region is irradiated with the laser light L. That is, the light reflection control unit 196 controls the galvano units 121 and 122 so that the region is irradiated with the laser light L. Specifically, the light reflection control unit 196 controls the drive units of the galvano units 121 and 122 so that the laser light L is reflected onto the determined region. The light reflection control unit 196 is not particularly limited, and examples thereof include a personal computer. When a personal computer is used as the light reflection control unit 196, it is preferable that its display unit be the monitor 195 of the image processing unit 190. The light reflection control unit and the image processing unit may be provided separately.

[0064] By using the ablation unit 100 having such a configuration, the analysis method and the ablation method can be easily performed.

[0065] (Determining Step) In the determining step, multiple regions are determined for one or multiple objects to be irradiated with the pulsed laser light. The irradiation regions are preferably determined by tracing the image displayed on the monitor 195. Specifically, the region is determined by tracing the displayed object with a touch pen or the like, and the laser light L is irradiated onto this determined region. The light reflection control unit 196 converts the determined region into coordinate information and controls the drive unit based on this coordinate information. Note that tracing means moving the touch pen or the like across the monitor 195 while maintaining contact with the monitor 195, and also includes contacting the touch pen or the like with the monitor 195 at a single point.

[0066] In the determining step, multiple regions may be determined for one object, or one or multiple regions may be determined for each of multiple objects. That is, one object may be accommodated in cell 170, and multiple irradiation regions may be determined for this object, or multiple objects may be accommodated in cell 170, and one or multiple irradiation regions may be determined for each of the multiple objects.

[0067] The above-mentioned determining step includes a procedure of placing cell 170 containing the object to be measured on stage 180. Cell 170 is preferably fixed so as not to move relative to stage 180. A gas supply pipe P1 and a gas exhaust pipe P2 are connected to cell 170 placed on stage 180, and preparations are made for the supply and exhaust of carrier gas.

[0068] The determining step also includes a procedure for selecting either transmission of the laser light L through the fθ lens 130 or transmission of the objective lens 140. The switching unit switches between transmission of the laser light L through the fθ lens 130 and the objective lens 140. When a relatively large number of regions are involved, or when the areas of the regions are relatively large, efficient ablation can be achieved by selecting the fθ lens 130. For ablation of a relatively small region, analysis of the object in the depth direction, or high-precision analysis of the object, it is preferable to select the objective lens 140.

[0069] The determining step includes a procedure of displaying images of the object captured by cameras 191, 192, and 193 on monitor 195. Specifically, the object placed on stage 180 and captured by first camera 191, second camera 192, or third camera 193 is displayed on monitor 195. It is preferable to determine the irradiation area by tracing the image displayed on monitor 195. It is preferable that the object is displayed on monitor 195 until irradiation of laser light L is completed. In this way, the operator can observe the state of the object before and after irradiation with laser light L, and the state of the object being ablated.

[0070] (Irradiation Step) In the irradiation step, the determined regions are sequentially or alternately irradiated with a set number of pulses of pulsed laser light L. That is, the number of pulses of the pulsed laser light L to be irradiated is set for each of the determined regions, and one region and the other regions are partially ablated sequentially or alternately with the set number of pulses. That is, the multiple regions are simultaneously ablated with the set number of pulses.

[0071] Specifically, when three regions are determined in the above-mentioned determination step, the m １ irradiating a first region with m pulses; １ + m including 1st time ２ irradiating a second region with m pulses; １ +m ２ + m including 1st time ３The third region is irradiated with a pulse of the pulsed laser light, and this is repeated sequentially to ablate the three regions in parallel. １ irradiating a first region with m pulses; １ + m including 1st time ２ The second region is irradiated with pulses m, and this is repeated alternately to ablate the two regions in parallel. １ , m ２ and m ３ is an integer of 1 or more, and m １ , m ２ , m ３ may be the same integer.

[0072] By arbitrarily setting the number of pulses of the pulsed laser light L to be irradiated to each region, the time ratio for ablation of each region can be changed, and therefore the aerosols generated in each of the above regions can be mixed in the desired ratio within the cell 170.

[0073] The number of pulses to be set may be one. That is, one pulse may be irradiated sequentially or alternately to each of the determined irradiation regions. In this way, the aerosols generated in each irradiation region can be mixed at a substantially uniform ratio while suppressing the time difference between the generation of these aerosols.

[0074] The conditions of the laser light L in the irradiation step, such as the output, wavelength, focused diameter, and pulse width, may be set appropriately depending on the physical properties of the object, the analysis method, the purpose of the analysis, etc. For example, when analyzing elements contained in a solid object, the analysis accuracy of the analysis unit 200 can be improved by setting the laser light L to a focused diameter of 2 μm or less, a wavelength region in the deep ultraviolet, a pulse width of 600 femtoseconds or less, and a repetition frequency of 1 kHz or more.

[0075] In the transporting step, the aerosol generated by the ablation is transported to the analysis unit 200. Specifically, the aerosol is discharged from the cell 170 together with the supplied carrier gas, and is transported to the analysis unit 200 through the gas exhaust pipe P2.

[0076] [Analyzing Step] In the analyzing step, the transported aerosol is analyzed by the analyzing unit 200. The analysis by the analyzing unit 200 is not particularly limited, and for example, the components of the target substance may be analyzed by a known analytical method such as inductively coupled plasma mass spectrometry or high frequency inductively coupled plasma atomic emission spectrometry.

[0077] Second Embodiment Another embodiment of the ablation method includes a step of determining one region on each of two objects to be irradiated with pulsed laser light L, and a step of irradiating the determined regions with the pulsed laser light alternately, one pulse at a time.

[0078] [Determining Step] In the determining step, two objects are placed in the cell 170, and one irradiation area is determined for each of the two objects.

[0079] [Irradiation Step] In the irradiation step, the two determined regions are alternately irradiated with one pulse of pulsed laser light L each.

[0080] This ablation method alternately irradiates one irradiation area on two objects with one pulse each, thereby reducing the time difference in aerosol generation in each irradiation area. By alternately irradiating one pulse each, the ablated volume in each irradiation area can be made approximately uniform, and the time difference in aerosol generation can be reduced. This makes it possible to promote simultaneous aerosol generation and equalize the mixing ratio.

[0081] [Other Embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention.

[0082] The ablation method and the ablation unit are not limited to being used in an analysis unit, but may also be used in, for example, a laser processing machine that processes an object with laser light.

[0083] The ablation unit may include another fθ lens (second fθ lens) upstream of the objective lens, i.e., the laser light may be configured to pass through the second fθ lens and then pass through the objective lens to ablate the target object.

[0084] The ablation unit is not limited to the above-described configuration. For example, it may be one that includes either an fθ lens or an objective lens, or one that includes two laser emission units, one for the fθ lens and one for the objective lens. The ablation unit may also have only one objective lens. The stage may be immovable, and may have two stages, for example, a first stage for the objective lens and a second stage for the fθ lens.

[0085] The ablation unit may also include other optical lenses such as an imaging lens, other optical mirrors such as a half mirror, and an illumination device for illuminating the object, as long as the ablation of the object is not hindered.

[0086] An ablation method according to one aspect of the present disclosure can be used in an ablation unit connected to an analysis unit that uses a laser to analyze elements contained in a target object, thereby enabling efficient analysis.

[0087] 10 Analysis unit 100 Ablation unit 110 Laser emission section 121, 122 Galvano section 121a First reflecting mirror 121b Second reflecting mirror 122a Third reflecting mirror 122b Fourth reflecting mirror 130 fθ lens 140 Objective lens 141 First objective lens 142 Second objective lens 143 Third objective lens 144 Lens holder 151 Reflecting mirror for objective lens 152 Reflecting mirror for fθ lens 161 First laser reflecting mirror 162 Second laser reflecting mirror 163 Third laser reflecting mirror 170 Cell 171 Gas supply port 172 Gas exhaust port 180 Stage 190 Image processing section 191 First camera 192 Second camera 193 Third camera 194 Periscope 195 Monitor 196 Light reflection control unit 200 Analysis unit L Laser light P1 Gas supply pipe P2 Gas exhaust pipe

Claims

1. An ablation method comprising the steps of: determining a number of regions on one or more objects to be irradiated with pulsed laser light; and sequentially or alternately irradiating the determined regions with a set number of pulses of pulsed laser light.

2. The ablation method according to claim 1, wherein said determining step determines a plurality of regions in one object.

3. The ablation method according to claim 1, wherein said determining step determines one or more regions in each of a plurality of objects.

4. The ablation method according to claim 1, wherein the repetition frequency of said pulsed laser light is 1 kHz or more.

5. Ablation according to any one of claims 1 to 4, wherein the set number of pulses is one pulse.

6. An ablation method comprising the steps of: determining an area on each of two objects to be irradiated with pulsed laser light; and irradiating each of the determined areas with the pulsed laser light alternately, one pulse at a time.

7. An analytical method comprising the steps of: ablating an object using the ablation method according to claim 1 or 6; transporting an aerosol generated by said ablation to an analytical unit; and analyzing the transported aerosol in said analytical unit.

Images