Kinematic path method for laser-induced breakdown spectroscopy

Abstract

A method for composition analysis includes providing a sample having a surface and determining, with a controller, a plurality of equidistant locations following an oscillatory path along the surface. The oscillatory path is sinusoidal in at least one orthogonal dimension within a plane generally parallel to the surface. The method further includes, for each of the plurality of equidistant locations, moving an ablation spot along the oscillatory path to each equidistant location, causing an energy source to fire a pulse to provide a beam of electromagnetic energy to ablate material at the ablation spot, and collecting, in response to causing the energy source to fire the pulse, an emission spectrum with a spectroscopic instrument. The method further includes analyzing the emission spectrum to determine a composition at the surface.

Description

Technical Field

[0001] This disclosure generally relates to systems and methods for performing laser-induced breakdown spectroscopy. Background Technology

[0002] Elemental analysis techniques help determine the elemental composition of materials in a wide variety of forms. The range of elemental analysis techniques is from destructive (e.g., the material is destroyed during testing) to semi-destructive (e.g., the material is sampled or its surface is damaged) to fully non-destructive (e.g., the material remains intact). Example techniques may include inductively coupled plasma atomic emission spectrometry (e.g., ICP-AES), ICP-mass spectrometry (e.g., ICP-MS), electrothermal atomization atomic absorption spectrometry (e.g., ETA-AAS), X-ray fluorescence spectrometry (e.g., XRF), X-ray diffraction (e.g., XRD), and laser-induced breakdown spectroscopy (e.g., LIBS). Elemental analysis can be qualitative or quantitative and typically requires calibration against known standards.

[0003] Laser-induced breakdown spectroscopy (LIBS) is an analytical technique used to analyze a wide variety of materials, including metals, polymers, glasses, ceramics, and minerals. LIBS can detect and quantify elements in the periodic table with very high accuracy. It can perform analysis on samples of varying sizes, requires little or no sample preparation, and can be used for bulk elemental analysis and microscanning imaging. LIBS relies on the emission of pulsed energy (such as pulsed laser emission) directed at the sample to ablate the material, causing it to atomize and ionize. The impact of each laser pulse on the sample surface generates a plasma plume, from which the light can be analyzed to perform qualitative or quantitative spectroscopic measurements. Therefore, LIBS offers easy-to-use, rapid in-situ chemical analysis with high accuracy, detection limits, and low cost.

[0004] The interaction of lasers with matter depends on quantum mechanics, which describes how photons are absorbed or emitted by atoms. If an atom absorbs a photon, one or more electrons move from the ground state to a higher energy quantum state. Electrons tend to occupy the lowest possible energy level, and during cooling / decay, the atom emits a photon to return to the lower energy level. For each atom, different energy levels produce different photon energies, resulting in narrow-band emission due to their quantization. These emission lines correspond to the spectral emission lines present in the LIBS spectrum.

[0005] Plasma lifetime consists of three basic phases. The first phase is the ignition process, which includes initial bond breaking and plasma formation during the laser pulse. This ignition process is influenced by the laser type, laser power, and pulse duration. The second phase of plasma lifetime is the most critical for optimizing LIBS spectral acquisition and measurement because the plasma induces atomic emission during the cooling process. After ignition, the plasma continues to expand and cool. Simultaneously, electron temperature and density change. This process depends on the ablation quality, spot size, energy coupled to the sample, and environmental conditions (sample state, pressure, etc.).

[0006] The final stage of the plasma lifetime is less useful for LIBS measurements. A certain amount of ablation mass is not excited into vapor or plasma; therefore, the material is ablated into particles, and these particles generate non-radiative condensed vapor, liquid sample ejection, and solid sample stripping. Furthermore, the ablated atoms cool and generate nanoparticles during plasma recombination. Attached Figure Description

[0007] This disclosure will be better understood by referring to the accompanying drawings, and its many features and advantages will become apparent to those skilled in the art.

[0008] Figure 1 Includes an illustration of an example laser-induced breakdown spectroscopy system.

[0009] Figure 2 Includes an illustration of an example laser-induced breakdown spectroscopy system.

[0010] Figure 3 and Figure 4 An illustration of an example apparatus for performing laser-induced breakdown spectroscopy.

[0011] Figure 5 Includes a beam diagram of an example laser-induced breakdown spectroscopy system.

[0012] Figure 6 and Figure 7 Includes a block flowchart illustrating an example method for performing laser-induced breakdown spectroscopy.

[0013] Figure 8 and Figure 9 Illustrations of example scan patterns used by a laser-induced breakdown spectroscopy system.

[0014] Figure 10 Includes a block flowchart illustrating an example method used by a laser-induced breakdown spectroscopy system.

[0015] Figure 11 , Figure 12 , Figure 13 and Figure 14 Illustrations of example scan patterns used by a laser-induced breakdown spectroscopy system.

[0016] Figure 15 An illustration of an example pattern including ablation points.

[0017] Figure 16 and Figure 17 Includes a diagram showing the movement pattern to adjacent ablation points.

[0018] Using the same reference numerals in different figures indicates similar or identical items. Detailed Implementation

[0019] In an embodiment, the system for compositional analysis includes an energy source to provide an energy beam directed at ablation points on the surface of a sample. The energy source may be, for example, a laser. The ablation points can be sequentially moved along an oscillating path to various locations (sample points) on the surface. In an example, the locations may be set at equidistant positions along the oscillating path. In an example, the oscillating path comprises a sinusoidal pattern in at least one orthogonal dimension in a planar dimension. The system may include a controller that guides the movement of the ablation points to positions along the oscillating path. The system may also include lenses and mirrors, or optionally a linear stage platform, to facilitate the movement of the ablation points. The energy beam ablates the material from the surface of the sample at the ablation points. The ablated material emits an emission spectrum. The system may include a collection system to collect the emission spectrum. In an example, the collection system includes a collection lens optically connected to a spectrometer or spectrometer to determine the wavelengths emitted by the ablated material. The system can use the emission spectrum to determine which elements are present and, optionally, in what quantities.

[0020] In yet another example, the method for compositional analysis includes providing a sample having a surface. At each location (sample point) sequentially along an oscillation path, the surface material at that location is ablated, emission spectra are collected, and the emission spectra are analyzed to determine the composition at the surface. Optionally, the emission spectra are converted into digital signals for further analysis to determine the composition. The composition can be analyzed, for example, by averaging, to determine the average surface composition. In another example, the composition at a location can be used to form an image or graph of the composition resolved according to location.

[0021] It has been found that conventional scanning methods, especially when used with irregular shapes, fail to provide rapid, distributed coverage of surfaces. When averaging the composition on a surface, conventional methods tend to overemphasize one area of ​​the surface relative to another. The system and method described in this paper advantageously provide uniform coverage and testing speed, among other benefits.

[0022] Figure 1This diagram includes a system 1 for performing compositional analysis, for example, by laser-induced breakdown spectroscopy. A sample 2 is placed on a platform 4. An energy source 6 directs an energy beam 8 via an optical system (such as a lens 10) to an ablation point 12 located on the surface of the sample 2. Material is ablated from the surface of the sample 2, and at least a portion of the ablated material is atomized or ionized, thereby generating an emission spectrum 14, which is collected by a collecting lens 16, for example, optically connected to a spectrometer 18 using an optical fiber cable.

[0023] Energy source 6 can be a laser. In this example, energy source 6 is a pulsed laser with a wavelength range of 200 nm to 1100 nm, such as 1064 nm, 532 nm, or 266 nm. Furthermore, the peak power of energy source 6 can range from 0.5 MW / cm². 2 Up to 2GW / cm 2 Such as at least 1MW / cm 2 This is sufficient to ablate materials from the surface of a sample and probe its elemental composition. For example, the laser pulse can have an energy in the range of 100 μJ to 100 mJ and a pulse width in the femtosecond, picosecond, or nanosecond range, with pulse repetition rates up to the MHz level. The laser can be a mode-locked laser or a Q-switched laser. For example, the laser can be a passive Q-switched laser or an active Q-switched laser.

[0024] Lens 10 may include a spherical lens, a flat-field scanning lens (e.g., an F-tan(θ) scanning lens), or an F-θ scanning lens. In particular, lens 10 is an F-θ scanning lens.

[0025] The collection system may include a collection lens 16 and a spectrometer 18. In one example, the spectrometer includes an imaging device, such as a charge-coupled device (CCD) imaging device. In yet another example, the emission spectrum may be guided to the spectrometer by one or more mirrors. In additional examples, the spectrometer may include various optical components, such as one or more mirrors, lenses, apertures, gratings, prisms, and emission collection devices. In this example, the emission collection device is a charge-coupled device (CCD). However, in other examples, other emission detectors may be used.

[0026] Specifically, system 1 includes a controller 20. In this example, controller 20 controls the relative movement of the ablation point 12 to its position on the surface of sample 2. For example, controller 20 controls a linear stage translation stage (such as platform 4) to move sample 2 relative to the fixed beam 8. In another example, mirrors such as galvanometers, prisms, or lenses can be used to change the relative position of the ablation point on the fixed sample. Controller 20 controls the relative movement of the ablation point 12 along an oscillation path to its position on the surface of sample 2. Based on the collection of emission spectra at each position on the surface of sample 2, it is possible to construct a compositional map of the scanned surface.

[0027] The controller 20 can also control the timing of the laser 6 to ablate the material only at desired locations on the sample surface. In addition, the controller 20 can control a collection system (such as a spectrometer 18) to collect the emission spectrum at a certain time relative to the activation of the laser 6.

[0028] In this example, controller 20 may also allow selection of a test area on the surface of sample 2. For example, controller 20 may use a laser system to detect the edges of the surface and select the entire surface area. In another example, controller 20 may use an optional camera 11 to detect the edges of the surface. In yet another example, controller 20 may provide an interface to a user that allows the user to select an area on the surface for testing.

[0029] As an alternative to a translation stage, the system may include a set of one or more fixed mirrors and movable positioning mirrors (such as galvanometers) that guide the electromagnetic energy beam through the lens to the ablation point on the surface of the sample. In the example, the motor-driven mirrors can be automatically controlled and adjusted to guide the ablation point to a position (sample point) sequentially set along an oscillation path on the surface of sample 2. In the example, controller 20 controls the adjustable mirrors to adjust the position (sample point) of the ablation point 12 on the surface of sample 2. Specifically, controller 20 is configured, for example, to move the ablation point to a position sequentially set along an oscillation path by controlling the motor driving the adjustable mirrors.

[0030] Controller 20 may include a computer (not shown): for example, including a storage medium, memory, processor, and one or more interfaces connected together, such as a user output interface, a user input interface, and a network interface. The storage medium may be any form of non-volatile data storage device, such as one or more of a hard disk drive, magnetic disk, optical disk, ROM, etc. The storage medium may store one or more computer programs to cause controller 20 to adjust the location of ablation points 12 on the surface of sample 2. The memory may be any random access memory suitable for storing data or computer programs. The processor may be any processing unit suitable for executing one or more computer programs (such as those stored on the storage medium or in memory). The processor may include a single processing unit or multiple processing units operating in parallel, individually, or cooperatively with each other. During processing operations, the processor may store data to or from the storage medium or memory. An interface may be provided, which is any unit that provides an interface between the computer and the movable mirror or translation platform 4 and the energy source 6. The user input interface may be arranged to receive input from a user or operator. Users may provide such input via one or more input devices of the controller (such as a mouse (or other pointing device) or a keyboard), which are connected to or communicate with the user input interface. However, it should be understood that users may provide input to the computer via one or more additional or alternative input devices (such as a touchscreen). The computer may store input received from the input device via the user input interface in memory for subsequent access and processing by the processor, or may pass the input directly to the processor so that the processor can respond accordingly to the user input. The user output interface may be arranged to provide graphical / visual output to the user or operator. For example, emission spectra collected from samples may be provided to the user or operator as graphical / visual output. Therefore, the processor may be arranged to instruct the user output interface to form an image / video signal representing the desired graphical output and to provide this signal to a video display unit (VDU) connected to the user output interface, such as a monitor (or screen or display unit). It should be understood that the above computer architecture is merely exemplary, and other computer systems with different architectures (e.g., with fewer components or with additional or alternative components) may be used. As an example, a computer may include one or more of the following: a personal computer; a server computer; a laptop computer; etc.

[0031] Figure 2The illustration includes a laser-induced breakdown spectroscopy (LIBS) system 100, comprising a pulsed laser 113, a beam expander 111, a biaxial scanning galvanometer system 110, a lens 108, a chamber 103, one or more mirrors 105, associated lenses 116, and one or more spectrometers 117. A sample 101 may be positioned on a stage including an opening or analysis aperture to expose the sample surface to the interior of the chamber 103.

[0032] Laser source 113 emits light pulses 112, for example, having the characteristics described above relative to... Figure 1 The wavelength or power described. The pulse frequency of the laser source 113 can range from 1 Hz to 1000 Hz. Each pulse 112 is directed onto the surface of the sample 101, where a plasma 102 is generated. Light emitted from the plasma 102 can be collected by mirror 105 and directed through lens 116 to spectrometer 117. Corresponding detection of light intensity can be used to perform qualitative or quantitative spectroscopy, thereby producing the identification of elements and possible compositions on the surface.

[0033] Optionally, a beam expander 111 is positioned in the path of the laser beam 112 originating from the laser source 113 to increase the diameter of the laser beam 112. Increasing the diameter of the laser beam 112 reduces the power per unit area, thereby avoiding damage to optical components of mirrors such as the galvanometer system 110, and subsequently achieving a tighter focused spot on the sample surface. Therefore, the beam 112 is reflected from a larger area 109 upon impact with the mirror 110. In this example, the beam expander 111 includes an entrance lens 111B and an exit lens 111A.

[0034] The galvanometer system 110 may include two motorized mirrors 110A and 110B. Such motorized mirrors 110A and 110B, coupled to a lens 108 (such as an F-θ lens), can guide a drawn beam onto the surface of the sample 101. In this example, the lens 108 can focus a laser beam 112 onto the sample surface as a spot of approximately 10 μm. The laser intensity per unit area on the spot is sufficient to generate plasma 102. A portion of the light 104 emitted by the plasma 102 is recovered by one or more mirrors 105A, 105B, 105C, or 105D and focused onto one or more spectrometers 117 by one or more lenses 116A, 116B, 116C, or 116D. Although four mirrors 105A, 105B, 105C, and 105D and four corresponding lenses 116A, 116B, 116C, and 116D are shown, it should be understood that embodiments may include one or more such mirrors and one or more corresponding lenses.

[0035] The spectrometer 117 uses a slit 117A and a grating 117B to split the light 104 according to wavelength, and uses a linear array sensor 117C or a single-channel sensor 117D to detect the light. The sensor signal from the sensor 117C or 117D can be used to determine the elemental composition of the sample.

[0036] The sample 101 is coupled to the chamber 103 to allow the surface of the sample 101 to be exposed to the interior of the chamber 103. The chamber 103 may be hermetically sealed in other ways. For example, the lens 108 or 116 may include an O-ring 107 or 115.

[0037] Chamber 103 can be purged with a gas such as argon, nitrogen, helium, or air. The interior of chamber 103 can be maintained under pressure or vacuum. Gas can be injected into chamber 103 through opening 106 and exit from chamber 103 through second opening 114. Optionally, a vacuum pump can be connected to second opening 114 to evacuate chamber 103 as gas moves through it. The location of openings 106 or 114 allows gas flow through the chamber to reduce dead volume and remove dust generated by plasma 102. When a vacuum pump is connected to second opening 114, dust can be removed by the vacuum pump. In particular, the quality and properties of plasma 102 and the generated emitted light 104 depend on the environment within chamber 103. Therefore, a sealed chamber 103 for dust removal is highly desirable.

[0038] like Figure 3 As shown in the example LIBS system, a sample stage 201 with an analysis aperture 202 is positioned above chamber 210. The sample can be held in place by a sample press 209. A laser system 207 is coupled to a lens 205 via a beam expander 206 and a galvanometer system, which directs the laser pulses to the surface of the sample exposed through the analysis aperture 202.

[0039] Light emitted from the plasma generated by the impact of a laser pulse on the sample surface through the analysis aperture 202 can be collected by mirrors held by plasma viewing mirror holders 204A and 204B. In one example, the light collected by the mirror coupled to plasma viewing mirror holder 204A is guided to the spectral lens 208. In another example, the light collected by the mirror attached to plasma viewing mirror holder 204B is projected onto the spectrometer 203.

[0040] Figure 4 Further examples of... Figure 1Details related to the LIBS system. The sample press 301 secures the sample to the sample stage 303, which has an analysis aperture 304 leading to the interior of the chamber 313. Laser pulses guided through the beam expander 309 and the F-θ lens 308 can impact the sample through the analysis aperture 304. The F-θ lens 308 can be supported by an F-θ lens holder 310. A galvanometer system (such as...) is used... Figure 2 (As shown), laser pulses passing through beam expander 309 and F-θ lens 308 can irradiate the surface of the sample exposed through analysis aperture 304.

[0041] Light emitted from the generated plasma can be collected by mirrors 307A or 307B and can be guided through spectral lens 302 or directed to spectrometer 311. For example, light collected by mirror 307A can be redirected to spectrometer 311. In another example, light collected by mirror 307B can be guided to spectral lens 302. Mirrors 307A or 307B can be held in place by plasma observation mirror holders 306A or 306B, respectively.

[0042] In another example, chamber 313 may be configured for gas flow to draw away dust particles generated by plasma from the sample surface and sample aperture 304. For example, chamber 313 may have a gas inlet (not shown) located near the bottom of the chamber close to lens 308. Gas may flow upward through chamber 313 toward analysis aperture 304. Chamber 313 may define a flow tube 305 or a wall. Gas flows through the wall into an annulus connected to outlet 312. Optionally, outlet 312 may be connected to a vacuum pump that draws gas through chamber 313, through flow tube 305, into the annulus, and out of outlet 312.

[0043] Figure 5 An example path of light propagation through the system is shown. For example, a laser beam 410 may be guided to an electric mirror 409A or 409B of a galvanometer system and through an F-θ lens 408, which focuses the laser beam onto a sample plane 401. Upon impact with the sample at the sample plane 401, the laser beam generates a plasma 404 emitting light 405. The light 405 from the plasma 404 may impact mirrors 406A or 406B, which guide the collected light 405 onto a spectral lens 402 or through an inlet 403 into a spectrometer. In this example, the spectrometer (such as...) Figure 1 , Figure 2 or Figure 3 The spectrometer shown can collect spectra emitted by plasma and determine the elemental composition based on those spectra.

[0044] Figure 2 , Figure 3 , Figure 4 and Figure 5 Each of the components in the system shown may include each other or Figure 1 The system components and features are shown. In the example, Figure 2 , Figure 3 , Figure 4 and Figure 5 Each of the systems may also include those having relative to Figure 1 The controller described in terms of form and functionality. In yet another example, Figure 2 , Figure 3 , Figure 4 and Figure 5 Each of the components in the system may have, relative to Figure 1 The camera described.

[0045] A certain feature of the system (such as) Figures 1 to 5 Those shown are oscillatory scans on the surface of the sample used for bulk element analysis. In the example, oscillatory scans allow for averaging of a large number of sample points to obtain the desired statistical results after each measurement. The collection of numerous sample points on the surface of the sample under consideration improves the accuracy of qualitative or quantitative analysis. Measurements collected from numerous sample points on the surface are more representative of the sample composition than those from a single point. For example, the system can analyze surface areas with diameters from 1 mm to 10 mm compared to a single point with a diameter of approximately 10 μm.

[0046] Without the scanning capabilities of the aforementioned system, the laser ablates the same portion of the sample with each pulse, and the sample composition is analyzed at different depths after each pulse. This measurement technique is limited by a depth limit beyond which further analysis is impossible. For example, plasma may penetrate the pit until it is blocked by the pit's depth, or the laser's focus may no longer be sufficient to generate reliable plasma. In contrast, the scanning capability of the system of this invention increases the number of measurements while continuously detecting plasma at the focal point of the F-θ lens.

[0047] To perform accurate and representative analysis of a sample surface, it is desirable to use, for example, a scan path to perform distributed sampling on the surface. This scan path provides distributed sampling of the surface and improves mirror movement by reducing accelerated jitter. Specifically, the scan path can define the movement in at least one orthogonal dimension (e.g., the x or y dimension of the surface) as a sinusoidal pattern (e.g., sine or cosine). In the example, the sinusoidal pattern can be a function of time. For example, the sinusoidal pattern can include a periodic parameter. Furthermore, the sinusoidal pattern can have an amplitude that can be constant or a function of time or position. Generally, the first derivative of the sinusoidal pattern is also sinusoidal. For example, the sinusoidal pattern can be a sine or cosine pattern. In the example, when the sinusoidal pattern is sinusoidal, the first derivative is cosine and the second derivative is sine. The sinusoidal pattern and the sinusoidal derivative are beneficial for reducing accelerated jitter in mirror movement and for achieving continuity at the end of the scan path, allowing for multiple scans to increase the number of sampling points and thus increasing the accuracy of the analysis results.

[0048] Sample points can be defined, for example, along a sample path using a sinusoidal pattern. Sample points can be defined at equal intervals along the path. In the example, the equidistant sample points can be linearly equidistant or curvilinearly equidistant. The sinusoidal path and the equidistant sample points along it allow the mirror to make the desired movement, enabling it to quickly move the beam to the next sample point while remaining stationary at each point long enough for the laser to produce the desired plasma.

[0049] Figure 6 Includes a block flowchart illustrating an example method 600 for analyzing a sample. Method 600 includes inserting a sample, as shown at block 602. For example, the sample may be inserted into a chamber or placed on a platform within the chamber. In another example, the sample may be placed against a sample stage having an analytical aperture that exposes the surface of the sample to the interior of the chamber.

[0050] As shown in box 604, the system can determine an oscillation path defined on the surface of a sample. For example, an analytical orifice can define an area of ​​the sample exposed for testing. The oscillation path can utilize a sinusoidal pattern in at least one dimension of the area exposed on the surface of the sample. Alternatively, an irregular shape can be exposed on the surface, or an irregular shape can be selected by the instrument user. The system can define an oscillation path that provides a desired distribution of sample points across the surface of the irregularly shaped test area. In this example, the controller of the system can be as follows: Figure 1 The diagram illustrates how a camera is used to determine the shape of a surface and define an appropriate oscillation path that provides the desired distribution of sample points across the surface.

[0051] In the example, the oscillation path follows a sinusoidal pattern along at least one of the two orthogonal dimensions along the surface of the sample. For example, the oscillation path may have a sine or cosine pattern along at least one of the two orthogonal dimensions. For example, the oscillation path may have a sinusoidal pattern along the height dimension. The sinusoidal pattern can be characterized by a periodicity parameter and amplitude. The periodicity parameter can be specified to provide the number of oscillations across the surface in one orthogonal dimension. The amplitude can be constant. In another example, the amplitude can be a function of time. In yet another example, the amplitude can be a function of position.

[0052] In yet another example, both orthogonal dimensions are defined by sinusoidal patterns. In this example, the sinusoidal pattern in the first orthogonal dimension can be a sine pattern, while the sinusoidal pattern in the second orthogonal dimension is a cosine pattern. Each pattern can be defined by a periodicity parameter. The periodicity parameters of the two patterns along the two orthogonal dimensions can be the same. In another example, the periodicity parameters are different. For example, the ratio of the two periodicity parameters can be an integer. In this example, the ratio is an even integer. Alternatively, the ratio is an odd integer. The amplitudes associated with the sinusoidal patterns in the two orthogonal dimensions can be the same. For example, the amplitudes can be the same time function or the same constant. In another example, the amplitudes of each of the sinusoidal patterns in the two orthogonal dimensions are different. Furthermore, the amplitude of the sinusoidal pattern in the second dimension can be a constant, while the amplitude associated with the sinusoidal pattern in the first orthogonal dimension can be a position function.

[0053] In another example, an oscillatory path defining at least one sinusoidal pattern along at least one of the orthogonal dimensions may include a non-sinusoidal pattern in a second orthogonal dimension. For example, the sinusoidal pattern in the y-dimensional dimension may be a sinusoidal pattern with desired periodicity and amplitude, while the pattern in the x-dimensional dimension is linear, such as a linear time function.

[0054] Furthermore, sample points are defined along the oscillation path. For example, equidistant sample points can be defined sequentially along the oscillation path. The equidistant ablation points can be linearly equidistant or curvilinearly equidistant.

[0055] As shown in box 606, the ablation point of the laser can be guided to the next sample point along the oscillating path. Laser redirection can be achieved by moving the mirror to guide the ablation point to a new location. The inertial nature of the mirror may not allow it to completely stop its movement at each ablation point. However, the advantage of using the oscillating movement presented here is that the rotation of the mirror remains constant, allowing the mirror to smoothly continue its path. Since the laser pulses are several orders of magnitude faster than the mirror movement, each pulse impacts as if the mirror were effectively fixed in place. This results in each ablation point being guided to the desired location on the sample without any noticeable distortion of the ablation point.

[0056] The laser is activated, for example, as shown in box 608. As a result of the laser activation, one or more pulses strike the surface of the sample at the ablation point, thereby causing the formation of plasma that emits a spectrum characteristic of the sample at that point along the surface.

[0057] As shown in box 610, the emission spectrum is collected. For example, the emission spectrum can be collected by a mirror that directs the collected emission spectrum to a spectral lens or spectrometer. The spectrometer converts the emission spectrum into a signal, as shown in box 612.

[0058] As shown in box 614, the system can determine whether it has reached the last sample point along the oscillation path. If the last sample point has not been reached, the system can repeatedly move the ablation point along the oscillation path to the next sample point (as shown in box 606), activate the laser (as shown in box 608), collect the emission spectrum (as shown in box 610), and convert the emission spectrum into a signal (as shown in box 612).

[0059] Once the end of the oscillation path is reached, and the last sample point has been tested, the system can analyze the transformed signal, as shown in box 616. For example, the system can analyze the signal to determine the composition at each point. Furthermore, the system can average the measurements. In the example, the system can determine the mean, median, or mode of the measurements. For example, the system can determine the average composition of the measurements across the test sample points. Although the analysis is shown as occurring after the sampling process is complete, the analysis can be performed simultaneously with testing the sample points along the oscillation path.

[0060] Figure 7 A block flowchart of another method 700 for testing samples is included. Method 700 is particularly useful when the test surface is not defined by an orifice or other regularly shaped mechanical features associated with the device. In particular, samples including irregularly shaped test areas benefit from this method. Figure 7 The method.

[0061] In the example, method 700 includes inserting a sample into the system, as shown in block 702. For example, inserting the sample may include placing the sample on a stage such as a translation stage, or placing the sample above an opening exposed to the chamber.

[0062] Select a test area on the sample, as shown in box 704. For example, an image of the sample can be provided to the user to select the desired test area. In another example, the system can determine the edges associated with the surface of the sample and select the test area based on the edges of the sample surface. In some examples, the test area may have a regular shape, such as a circle or rectangle. In other examples, the selected test area may have an irregular shape.

[0063] As shown in box 706, the system can determine centerline and boundary parameters. For example, the system can determine the width of the test area at the centerline and the distance from the centerline to the boundary or edge.

[0064] Oscillation parameters (e.g., periodicity parameters or amplitude) can be determined to define the oscillation path, as shown in box 710. For example, a periodicity parameter can be defined as associated with a sinusoidal pattern following one or two orthogonal dimensions along the surface. Furthermore, an amplitude parameter can be determined for one or both patterns along two orthogonal dimensions.

[0065] As shown in box 712, the system can determine equidistant points along the oscillation path. For example, these points can be linearly equidistant along the oscillation path. In another example, these points can be curvilinearly equidistant along the oscillation path.

[0066] This system can test each sample point defined along an oscillation path. For example, the system can move the ablation point of the laser along the oscillation path to the next sample point, as shown in box 714. The laser can be pulsed once or multiple times to generate plasma, as shown in box 716.

[0067] The emission spectrum emitted by the plasma can be collected, as shown in box 718. The emission spectrum can then be converted into a signal, for example, by a spectral lens or spectrometer, as shown in box 720.

[0068] As shown in box 722, the system can determine whether it has reached the end of the sample points along the oscillation path or whether it has moved along the oscillation path to subsequent sample points. Once it has reached the end of the oscillation path, the system can analyze the transformed signal, as shown in box 724. For example, the system can determine the composition at each point along the surface. Furthermore, the system can determine the average composition. In the example, the system can determine the mean, median, or mode of the measurements. The system can average the measurements of the transformed signal and determine the composition based on the sum of the signals. Alternatively, the system can determine the composition at each point and calculate the average composition across the sample points.

[0069] Such methods can be used to define a pattern that provides a desired distribution of sample points across the surface of a test area of ​​various shapes. For example, the test area could be circular. In another example, the test area could be rectangular. In yet another example, the test area could be irregular.

[0070] For example, Figure 8An illustration of an example oscillation path covering a circular test area is provided. This path follows a spiral pattern. This pattern can be generated using sine curve patterns in all two orthogonal dimensions. In the example, the sine curve pattern in the first orthogonal dimension is a sine pattern, while the sine curve pattern in the second orthogonal dimension is a cosine pattern. Each sine curve pattern is a function of time. Furthermore, in the example shown, the periodicity parameter associated with each pattern is equal. The amplitude associated with each sine curve pattern is the same and is a function of time. For example, the pattern can be generated using the following equation (Equation 1). As described, the amplitude increases with time (t) until it reaches a maximum value, at which point the amplitude decreases.

[0071] (Equation 1)

[0072] x(t) = r(t)·cos(k·t); and

[0073] y(t) = r(t)·sin(k·t), where:

[0074] r(t) = k r ·t for 0 < t < t rmax And r(t) = r max -k r ·t for t rmax <t<t rzero

[0075] Where t rmax It is the time to reach the maximum radius (r(t)), and t rzero It is the time it takes for the radius (r(t)) to return to zero. k and k r It is a constant. Figure 9 Another example is shown of an oscillating path generated using a sinusoidal pattern along at least one of the two orthogonal dimensions of a surface. For example, the oscillating path could have a sinusoidal pattern in the y-dimension. A periodicity parameter can be defined to provide the number of oscillations across the surface. The amplitude α of the sinusoidal pattern is a constant, and k... y It is a constant.

[0076] (Equation 2) y(t)=α·sin(k y ·t)

[0077] The second dimension (such as the x-dimensionality) can be defined using a linear pattern or a sinusoidal pattern (such as a cosine pattern). In the example, the x-dimensionality is defined as a linear function that increases over time until it reaches the endpoint or full width, at which point the pattern uses a constant (k) at the same rate. x To reverse the direction.

[0078] (Equation 3) x(t)=k x ·t for 0 < t < txmax And x(t) = x max -k x ·t for t xmax <t<t xzero

[0079] Where t xmax It is the time when x(t) reaches its maximum width, and t xzero It is the time when x(t) returns to zero.

[0080] Alternatively, a sinusoidal pattern (such as a cosine pattern) with a periodicity different from that of the sinusoidal pattern in the first orthogonal dimension can be used to define the second dimension. In the example shown, the periodicity parameter of the sinusoidal pattern is 14 times that of the cosine pattern in the second orthogonal dimension. Therefore, for each oscillation across the width in the x-dimensional dimension, the oscillation path oscillates seven times between the boundaries in the y-dimensional dimension.

[0081] (Equation 4) x(t)=β·cos(k x ·t), where For example, i = 14)

[0082] Where β is a constant, and k x It is a constant.

[0083] Although Figure 8 and Figure 9 The diagram shows an oscillation path with an amplitude that is a constant or a function of time; however, it is alternatively possible to define the oscillation path using a pattern in which the amplitude in at least one dimension is a function of position.

[0084] Figure 10 A block flowchart illustrating a method 1000 for determining a sinusoidal pattern with amplitude varying with position is shown. For example, as shown in block 1002, the system can determine a centerline when a test area is selected. For example, the centerline can be defined along one of the orthogonal dimensions (e.g., the x-axis). In particular, the centerline can be selected at the maximum width along the x-axis.

[0085] As shown in box 1004, the system measures the width of the centerline. Based on the width of the centerline, the expected number of oscillations across the surface, and the expected number of sample points, the system can determine the periodicity parameter of a sinusoidal pattern in one or two orthogonal dimensions, as shown in box 1006. In this example, the ratio of the periodicity parameter is an even integer. Alternatively, the ratio of the periodicity parameter is an odd integer.

[0086] Once the periodicity parameter is determined, the position of each peak in the period of a sine curve pattern in at least one orthogonal dimension is known. For example, if a sine function or pattern is assigned to the y-dimensional dimension, the x-dimensional position of the peak of the sine curve pattern in the y-dimensional dimension can be determined based on the linear pattern or sine curve pattern in the x-dimensional dimension.

[0087] As shown in box 1008, the distance from the centerline to the edge of the test area at the x-position of each peak of the sine pattern in the y-dimensional dimension can be determined. In box 1010, the amplitude parameter of the sine pattern in the y-dimensional dimension can be determined based on the measured distance from the centerline at each peak. For example, whenever the sine pattern in the y-dimensional dimension crosses the centerline, the system can assign a new amplitude parameter to the sine pattern in the y-dimensional dimension.

[0088] Once the oscillation path is determined, the system can identify equidistant points along the oscillation path, as shown in box 1012. These equidistant points can serve as sample points.

[0089] For example, Figure 11 and Figure 12 An example oscillation path across a circular test area is shown. In the example shown, the oscillation path has a sinusoidal pattern in the y-dimensional direction, such as a sine pattern. In yet another example, the pattern may include a sinusoidal pattern in the x-dimensional direction, such as a cosine pattern. The periodicity parameter of the sinusoidal pattern in the y-dimensional direction is 14 times that of the sinusoidal pattern in the x-dimensional direction. The amplitude of the cosine pattern in the x-dimensional direction is constant. However, the amplitude of the sinusoidal pattern in the y-dimensional direction is a position function. For example, the amplitude α of the sinusoidal function in the y-dimensional direction can change based on the distance to the outer edge whenever the oscillation path crosses the center line.

[0090] (Equation 5)

[0091] x(t)=β·cos(k x ·t); and

[0092] y(t)=α(x)·sin(k y ·t),

[0093] in (For example, i = 14).

[0094] Where k x k y And β are constants.

[0095] For example, such as Figure 12As shown, the system can determine a centerline with a width W in the x-axis. The amplitude of the cosine pattern in the x-axis can be selected such that the pattern spans the entire width in each period. The periodicity of the sine pattern associated with the y-axis can be selected such that the ratio of the periodicity of the sine pattern to the periodicity parameter of the cosine pattern is an integer, such as 14.

[0096] Based on a known cosine pattern extending in the x-axis, the x-position of each peak of a sine pattern in the y-axis is known. The system can then determine the distance from the centerline to the edge at each peak of the sine pattern, and determine the amplitude of the sine pattern based on this distance. For example, whenever the sine pattern crosses the centerline downwards, the distance to the edge can be determined, and the amplitude of the sine pattern can be determined based on the distance H'. Similarly, when the sine pattern crosses the centerline upwards, the distance H can be determined, and the amplitude of the sine pattern can be determined based on the distance H.

[0097] Figure 13 and Figure 14 This includes additional illustrations of applying this method to irregular test areas. A centerline and its width W can be determined. Based on the determined centerline, a pattern associated with the x-axis can be determined. In one example, the pattern can be linear (e.g., Equation 3). In another example, the pattern can be sinusoidal, such as a cosine pattern (e.g., Equation 4).

[0098] The periodicity parameter of the sinusoidal pattern in the y-dimensional dimension can be determined based on the expected number of oscillations across the surface during each period of the cosine pattern in the x-dimensional dimension. In the example shown, the ratio of the periodicity parameter in the y-dimensional dimension to the periodicity parameter in the x-dimensional dimension is 11. The amplitude of the sinusoidal pattern in the y-dimensional dimension can be a position function (e.g., Equation 5). For example, for each peak, the distance H or H' from the center line can be determined. The amplitude can be set based on the intersection of the center line with a given peak of the sinusoidal pattern in the y-dimensional dimension. Thus, an irregular pattern can be traversed from edge to edge, thereby providing a sample distribution.

[0099] For each oscillation path, the system can determine equidistant sample points along that path for testing using laser ablation of the surface. For example, as Figure 15 As shown, the oscillation path may include equidistant sample points. These equidistant sample points can be determined based on a linear distance, as shown at 1504 (e.g., Equation 6). Alternatively, the distance can be determined based on a curved distance along the oscillation path, as shown at 1506 (e.g., Equation 7).

[0100] (Equation 6)

[0101] (Equation 7)

[0102] When a laser pulse is directed to a surface to generate plasma, the mirror guiding the laser can be stationary. The laser pulse can be stopped when the laser is redirected. For example, as... Figure 16 As shown, the laser is activated during a time period (P) when the ablation point is stationary at a sample point along the oscillating path. Once the pulse has stopped, the system can redirect the laser, thereby moving the ablation point during a time period (M). The movement during the time period (M) can have an S-shape when considered as a change in position over time. The first derivative of the S-shaped movement provides a velocity with a triangular shape, and the second derivative provides an acceleration described as a square wave. Therefore, an oscillating path with equidistant sample points along the path provides a rapid movement between the position and time period of a point along the oscillating path when the system is stationary.

[0103] For example, such as Figure 17 As shown, after a period (P) in which one or more pulses are directed at the sample surface, there is a rapid movement during a period (M) to redirect the ablation point of the laser to the next sample point. Therefore, based on the positioning of points along the path, the kinematic properties between each point can be defined, where, in one cycle, the mirror remains stationary for a period long enough to allow the laser to generate multiple pulses at the same point on the sample surface. This period is typically on the order of milliseconds. This stationary positioning provides stable and reproducible plasma, thus improving analytical performance. During the second part or cycle of the kinematic movement, an sigmoid profile (displacement varying over time) is used to move the ablation point to the next sample point. This profile provides the desired velocity between points and an acceleration distribution that ensures smooth mirror dynamics. By utilizing both the sinusoidal pattern with equidistant sample points and the kinematic properties with the sigmoid profile, a system with low scan errors and desired analytical performance is provided. Furthermore, the analysis can be repeated at desired rates of approximately kilohertz or greater.

[0104] In a first embodiment, a method for compositional analysis includes: providing a sample having a surface; and determining, with a controller, a plurality of equidistant locations along an oscillation path following the surface. The oscillation path is sinusoidal in at least one orthogonal dimension in a plane substantially parallel to the surface. For each of the plurality of equidistant locations, the method includes: moving an ablation point along the oscillation path to each equidistant location; causing an energy source to transmit a pulse to provide an electromagnetic energy beam to ablate the material at the ablation point; and collecting an emission spectrum with a spectrometer in response to causing the energy source to transmit the pulse. The method further includes analyzing the emission spectrum to determine the composition at the surface.

[0105] In an example of the first implementation, moving the ablation point involves moving the sample using a translation plate.

[0106] In another example of the first implementation scheme and in the example above, moving the ablation point includes positioning the mirror.

[0107] In another example of the first embodiment and in the example above, multiple equidistant positions are linearly equidistant along the oscillation path.

[0108] In the additional example of the first embodiment and the example above, multiple equidistant positions are equidistant along the oscillation path curve.

[0109] In another example of the first implementation scheme and in the example above, the oscillation path varies proportionally with time in another orthogonal dimension within the plane.

[0110] In another example of the first embodiment and the examples above, the oscillation path is sinusoidal in another orthogonal dimension of the plane. For example, the oscillation path is continuously differentiable. In another example, the oscillation path varies with one of the sine or cosine functions of time in at least one orthogonal dimension of the plane, and with the other of the sine or cosine functions of time in another orthogonal dimension of the plane. In yet another example, the oscillation path varies with a first periodicity in at least one orthogonal dimension of the plane, and with a second periodicity in another orthogonal dimension of the plane, where the first periodicity is an integer multiple of the second periodicity. For example, this integer multiple is in the range of 1 to 100, such as in the range of 2 to 20. In an additional example, the integer multiple is 1 and the amplitude of the oscillation path in both the first and second dimensions is proportional to time. In another example, the amplitude of the oscillation path in the first dimension is a function of the position in the other orthogonal dimension.

[0111] In the additional example of the first embodiment and the example above, analyzing the emission spectrum includes averaging the composition of each of a plurality of equidistant locations.

[0112] In another example of the first embodiment and the examples described above, the method further includes selecting a test region on the surface of the sample, within which the oscillation path lies. For example, the method further includes determining a centerline of the test region and determining the width of the centerline, which extends in another orthogonal dimension within the plane. In the example, the method further includes using a controller to determine the distance from the centerline of the test region to the edge in at least one orthogonal dimension at the peak of the sinusoidal oscillation, and adjusting the amplitude of the sinusoidal oscillation based on this distance.

[0113] In a second embodiment, a system for laser-induced breakdown spectroscopy includes: a stage for receiving a sample; a laser source for providing a laser beam; and a mirror system for guiding the laser beam to a surface of the sample. The laser beam ablates a portion of the sample at the ablation point and induces plasma that emits an emission spectrum. The system also includes a spectroscopic instrument for receiving the spectrum and a controller in communication with the mirror system. The controller determines a plurality of equidistant locations along an oscillation path following the surface. The oscillation path is sinusoidal in at least one orthogonal dimension in a plane substantially parallel to the surface. The controller controls the mirror system to move the ablation point along the oscillation path to each equidistant location.

[0114] In an example of the second implementation, the controller communicates with the laser source and directs the laser to send laser beams in pulses.

[0115] In another example of the second implementation scheme and the example described above, the controller communicates with a spectrometer and guides the spectrometer to collect emission spectra. For example, the controller analyzes the emission spectra to determine the composition at the surface.

[0116] In another example of the second embodiment and the example above, the system further includes a beam expander in the path of the laser beam prior to the mirror system.

[0117] In the additional example of the second embodiment and the example above, the system also includes an F-θ lens in the path of the laser beam following the mirror system.

[0118] In another example of the second implementation scheme and the example above, multiple equidistant positions are linearly equidistant along the oscillation path.

[0119] In another example of the second implementation scheme and the example above, multiple equidistant positions are equidistant along the oscillation path curve.

[0120] In the additional example of the second implementation scheme and the example above, the oscillation path varies proportionally with time in another orthogonal dimension within the plane.

[0121] In another example of the second embodiment and the examples above, the oscillation path is sinusoidal in another orthogonal dimension of the plane. For example, the oscillation path is continuously differentiable. In another example, the oscillation path varies with one of the sine or cosine functions of time in at least one orthogonal dimension of the plane, and with the other of the sine or cosine functions of time in another orthogonal dimension of the plane. In yet another example, the oscillation path varies with a first periodicity in at least one orthogonal dimension of the plane, and with a second periodicity in another orthogonal dimension of the plane, where the first periodicity is an integer multiple of the second periodicity. For example, the integer multiple is in the range of 1 to 100, such as in the range of 2 to 20. In the example, the integer multiple is 1 and the amplitude of the oscillation path in both the first and second dimensions is proportional to time. In an additional example, the amplitude of the oscillation path in the first dimension is a function of the position in the other orthogonal dimension.

[0122] In another example of the second implementation scheme and the example above, the controller analyzes the emission spectrum by averaging the composition of each of a plurality of equidistant locations.

[0123] In an additional example of the second embodiment and the example described above, the controller selects a test area on the surface of the sample, within which the oscillation path lies. For example, the controller determines the centerline of the test area and the width of the centerline, which extends in another orthogonal dimension within the plane. In the example, the controller determines the distance from the centerline of the test area to the edge in at least one orthogonal dimension at the peak of the sinusoidal oscillation, and adjusts the amplitude of the sinusoidal oscillation based on this distance.

[0124] In a third embodiment, a method for compositional analysis includes: providing a sample having a surface; and determining, with a controller, multiple locations along an oscillation path following the surface. The oscillation path is sinusoidal in two orthogonal dimensions in a plane generally parallel to the surface. The oscillation path varies over time in the two orthogonal dimensions. For each of the multiple locations, the method includes: moving an ablation point along the oscillation path to each location; causing an energy source to send a pulse to provide an electromagnetic energy beam to ablate the material at the ablation point; and collecting an emission spectrum with a spectrometer in response to causing the energy source to send the pulse. The method also includes analyzing the emission spectrum to determine the composition at the surface.

[0125] In the example of the third implementation scheme, the multiple locations are multiple equidistant locations set sequentially along the oscillation path.

[0126] In another example of the third implementation scheme and the example above, multiple equidistant positions are linearly equidistant along the oscillation path.

[0127] In another example of the third implementation scheme and the example above, multiple equidistant positions are equidistant along the oscillation path curve.

[0128] In the additional example of the third implementation scheme and the example above, the oscillation path is continuously differentiable.

[0129] In another example of the third implementation scheme and the example above, the oscillation path varies with one of the two orthogonal dimensions in the plane as a function of the sine or cosine of time, while in the other of the two orthogonal dimensions in the plane, the oscillation path varies with the other of the two orthogonal dimensions of time.

[0130] In another example of the third embodiment and the example above, the oscillation path varies with a first periodicity in one of the two orthogonal dimensions in the plane, and with a second periodicity in the other of the two orthogonal dimensions in the plane, wherein the first periodicity is an integer multiple of the second periodicity. For example, this integer multiple is in the range of 1 to 100, such as in the range of 2 to 20. In an additional example, the integer multiple is 1 and the amplitude of the oscillation path in at least one dimension and the other dimension is proportional to time. In yet another example, the amplitude of the oscillation path in at least one dimension is a function of the position in the other orthogonal dimension.

[0131] In the additional example of the third implementation scheme and the example above, analyzing the emission spectrum includes averaging the composition of each of a plurality of equidistant locations.

[0132] In another example of the third embodiment and the examples described above, the method includes selecting a test region on the surface of the sample, with the oscillation path within the test region. For example, the method further includes determining a centerline of the test region and determining the width of the centerline, which extends in another orthogonal dimension within the plane. In the example, the method further includes using a controller to determine the distance from the centerline of the test region to the edge in at least one orthogonal dimension at the peak of the sinusoidal oscillation, and adjusting the amplitude of the sinusoidal oscillation based on this distance.

[0133] In a fourth embodiment, a system for laser-induced breakdown spectroscopy includes: a stage for receiving a sample; a laser source for providing a laser beam; and a mirror system for guiding the laser beam to a surface of the sample. The laser beam ablates a portion of the sample at the ablation point and induces plasma that emits an emission spectrum. The system also includes a spectroscopic instrument for receiving the spectrum and a controller in communication with the mirror system. The controller determines multiple locations along an oscillation path following the surface. The oscillation path is sinusoidal in two orthogonal dimensions in a plane generally parallel to the surface. The oscillation path varies over time in the two orthogonal dimensions. The controller controls the mirror system to move the ablation point along the oscillation path to each location.

[0134] In an example of the fourth implementation, the controller communicates with the laser source and directs the laser to send laser beams in pulses.

[0135] In yet another example of the fourth embodiment and the examples above, the controller communicates with a spectrometer and guides the spectrometer to collect emission spectra. For example, the controller analyzes the emission spectra to determine the composition at the surface.

[0136] In another example of the fourth embodiment and the examples above, the system also includes a beam expander in the path of the laser beam prior to the mirror system.

[0137] In the additional example of the fourth embodiment and the example above, the system also includes an F-θ lens in the path of the laser beam following the mirror system.

[0138] In another example of the fourth embodiment and the examples above, the multiple locations are multiple equidistant locations arranged sequentially along the oscillation path. For example, the multiple equidistant locations are linearly equidistant along the oscillation path. In another example, the multiple equidistant locations are curvilinearly equidistant along the oscillation path.

[0139] In another example of the fourth implementation scheme and in the example above, the oscillation path is continuously differentiable.

[0140] In the additional example of the fourth embodiment and the example above, the oscillation path varies with one of the two orthogonal dimensions in the plane as a function of the sine or cosine of time, while in the other of the two orthogonal dimensions in the plane, the oscillation path varies with the other of the two orthogonal dimensions of time.

[0141] In another example of the fourth embodiment and the examples above, the oscillation path varies with a first periodicity in one of the two orthogonal dimensions in the plane, and with a second periodicity in the other of the two orthogonal dimensions in the plane, wherein the first periodicity is an integer multiple of the second periodicity. For example, this integer multiple is in the range of 1 to 100, such as in the range of 2 to 20. In another example, the integer multiple is 1 and the amplitude of the oscillation path in at least one dimension and the other dimension is proportional to time. In yet another example, the amplitude of the oscillation path in at least one dimension is a function of the position in the other orthogonal dimension.

[0142] In another example of the fourth implementation scheme and the example above, the controller analyzes the emission spectrum by averaging the composition of each of a plurality of equidistant locations.

[0143] In the additional example of the fourth embodiment and the example above, the controller selects a test area on the surface of the sample, within which the oscillation path lies. For example, the controller determines the centerline of the test area and the width of the centerline, which extends in another orthogonal dimension within the plane. In the example, the controller determines the distance from the centerline of the test area to the edge in at least one orthogonal dimension at the peak of the sinusoidal oscillation, and adjusts the amplitude of the sinusoidal oscillation based on this distance.

[0144] It should be noted that not all activities described above in the general description or examples are required; some specific activities may not be required; and one or more additional activities may be performed besides those described. Furthermore, the order in which the activities are listed is not necessarily the order in which they are performed.

[0145] In the foregoing specification, the concepts have been described with reference to specific embodiments. However, those skilled in the art will understand that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims. Therefore, the specification and drawings are to be regarded as illustrative rather than restrictive, and all such modifications are intended to be included within the scope of the invention.

[0146] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of features is not necessarily limited to those features, but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, unless expressly stated to the contrary, “or” refers to inclusive or not exclusive or. For example, any of the following satisfy conditions A or B: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and both A and B are true (or exist).

[0147] Additionally, the use of "a" or "an" is used to describe the elements and components described herein. This is done merely for convenience and to give a general meaning regarding the scope of the invention. This description should be understood to include one or at least one, and the singular includes the plural, unless it clearly refers to something else.

[0148] The benefits, other advantages, and solutions to the problems have been described above with respect to specific embodiments. However, the benefits, advantages, solutions to the problems, and any features that may cause any benefit, advantage, or solution to become apparent or more significant should not be construed as key, necessary, or essential features of any or all claims.

[0149] After reading this specification, those skilled in the art will understand that certain features described herein in the context of individual embodiments for clarity may also be provided in combination in a single embodiment. Conversely, various features described in the context of a single embodiment for brevity may also be provided individually or in any sub-combination. Furthermore, values ​​mentioned in the scope include every value within that scope.

Claims

1. A method for compositional analysis, the method comprising: Provide samples with surfaces; The controller determines multiple equidistant positions along an oscillation path that is sinusoidal in at least one orthogonal dimension in a plane substantially parallel to the surface, wherein the oscillation path is determined by the following steps: A test area is selected on the surface of the sample, and the oscillation path is within the test area; Determine the centerline of the test area and the width of the centerline, which extends in another orthogonal dimension within the plane; The controller is used to determine the distance from the center line of the test area to the edge of the test area in at least one orthogonal dimension at the peak of the sinusoidal oscillation; as well as The controller adjusts the amplitude of the sinusoidal oscillation based on the distance. For each of the plurality of equidistant positions: The ablation point is moved along the oscillation path to each of the equidistant positions; The energy source sends pulses to provide an electromagnetic energy beam to ablate the material at the ablation point; as well as The emission spectrum is collected by a spectrometer in response to the energy source emitting a pulse; as well as The emission spectrum is analyzed to determine the composition at the surface.

2. The method of claim 1, wherein moving the ablation point comprises moving the sample using a translation plate.

3. The method according to claim 1 or claim 2, wherein moving the ablation point includes positioning the mirror.

4. The method according to claim 1 or claim 2, wherein the plurality of equidistant positions are linearly equidistant along the oscillation path.

5. The method according to claim 1 or claim 2, wherein the plurality of equidistant positions are equidistant along the oscillation path curve.

6. The method according to claim 1 or claim 2, wherein the oscillation path varies proportionally with time in another orthogonal dimension within the plane.

7. The method according to claim 1 or claim 2, wherein the oscillation path is sinusoidal in another orthogonal dimension within the plane.

8. The method of claim 7, wherein the oscillation path is continuously differentiable.

9. The method of claim 7, wherein on the at least one orthogonal dimension in the plane, the oscillation path varies with one of the sine or cosine functions of time, and on the other orthogonal dimension in the plane, the oscillation path varies with the other of the sine or cosine functions of time.

10. The method of claim 7, wherein the oscillation path varies with a first periodicity in the at least one orthogonal dimension in the plane, and with a second periodicity in the other orthogonal dimension in the plane, wherein the first periodicity is an integer multiple of the second periodicity.

11. The method of claim 10, wherein the integer multiple is in the range of 1 to 100.

12. The method of claim 11, wherein the integer multiple is in the range of 2 to 20.

13. The method of claim 10, wherein the integer multiple is 1 and the amplitude of the oscillation path in both the at least one dimension and the other dimension is proportional to time.

14. The method of claim 10, wherein the amplitude of the oscillation path in the at least one dimension is a function of its position in the other orthogonal dimension.

15. The method of claim 1 or claim 2, wherein analyzing the emission spectrum comprises averaging the composition of each of the plurality of equidistant locations.

16. A system for laser-induced breakdown spectroscopy, the system comprising: The platform is used to receive samples; A laser source, wherein the laser source is used to provide a laser beam; A mirror system for guiding the laser beam to the surface of the sample, the laser beam ablates a portion of the sample at the ablation point and induces plasma, the plasma emitting an emission spectrum; A spectroscopic instrument, the spectroscopic instrument being used to receive the spectrum; and A controller, communicating with the mirror system, determines multiple equidistant positions along an oscillation path following the surface, the oscillation path being sinusoidal in at least one orthogonal dimension in a plane substantially parallel to the surface, and the controller controls the mirror system to move the ablation point along the oscillation path to each equidistant position, wherein the oscillation path is determined by the following steps: A test area is selected on the surface of the sample, and the oscillation path is within the test area; Determine the centerline of the test area and the width of the centerline, which extends in another orthogonal dimension within the plane; The controller determines the distance from the centerline of the test area to the edge of the test area in at least one orthogonal dimension at the peak of the sinusoidal oscillation; and The controller adjusts the amplitude of the sinusoidal oscillation based on the distance.

17. The system of claim 16, wherein the controller communicates with the laser source and directs the laser to transmit the laser beam in pulses.

18. The system of claim 16 or claim 17, wherein the controller communicates with the spectrometer, and the controller directs the spectrometer to collect the emission spectrum.

19. The system of claim 18, wherein the controller analyzes the emission spectrum to determine the composition at the surface.

20. The system of claim 16 or claim 17, further comprising an F-θ lens in the path of the laser beam following the mirror system.

21. The system of claim 16 or claim 17, wherein the plurality of equidistant positions are linearly equidistant along the oscillation path.

22. The system of claim 16 or claim 17, wherein the plurality of equidistant positions are equidistant along the oscillation path curve.

Images