Variable beam size by homogenizer movement

Abstract

An ablation system for ablating a material can include a laser source, a homogenization optics set, and a homogenization optics adjustment device. The laser source generates a laser beam, and the homogenization optics set receives the laser beam and includes a first homogenizer and a second homogenizer. The homogenization optics adjustment device is equipped with the homogenization optics and selectively adjusts the position of at least one of the first homogenizer and the second homogenizer to change the beam size of the laser beam, and the change in beam size changes the fluence of the laser beam. The ablation system can be incorporated into a laser ablation-based analysis system, which includes a spectrometer.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 978,516, filed February 19, 2020, and entitled "Variable Beam Size Through Homogenizer Movement," the contents of which are incorporated herein by reference. [Background technology]

[0002] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) or laser ablation inductively coupled plasma optical emission spectrometry (LA-ICP-OES) techniques can be used to analyze the composition of a target (e.g., a solid or liquid target material). Often, a sample of the target is provided to the analysis system in the form of an aerosol (i.e., a suspension of solid, and sometimes liquid, particles and / or vapor in a carrier gas, such as helium gas). The sample is typically generated by placing the target in a laser ablation chamber, introducing a flow of carrier gas into the chamber, and ablating a portion of the target with one or more laser pulses to generate a plume. The plume includes particles and / or vapor emitted or otherwise generated from the target (hereinafter referred to as the "target material") and suspended in the carrier gas. The target material entrained in the flowing carrier gas is transported to the analysis system via a transport conduit and delivered to a TCP torch where it is ionized. The plasma containing the ionized particles and / or vapor is then analyzed by an analytical system, such as an MS, OES, an isotope ratio mass spectrometry system (IRMS), or an electrospray ionization (ESI) system.

[0003] Further details are described with reference to the accompanying drawings. [Brief description of the drawings]

[0004] [Figure 1]FIG. 1 is a schematic diagram of an analytical system based on laser ablation, according to an exemplary embodiment of the present disclosure. [Figure 2A] 2 is a series of schematic diagrams of a laser source, a pair of homogenization optics (a first homogenizer and a second homogenizer), and a homogenization optics adjustment device of the laser ablation-based analysis system shown in FIG. 1, showing a confocal position relative to the homogenization optics adjustment device. [Figure 2B] 2 is a series of schematic diagrams of a laser source, a pair of homogenization optics (a first homogenizer and a second homogenizer), and a homogenization optics adjustment device of the laser ablation-based analysis system shown in FIG. 1, showing a minimum beam size position relative to the homogenization optics adjustment device. [Figure 2C] 2 is a series of schematic diagrams of a laser source, a pair of homogenization optics (a first homogenizer and a second homogenizer), and a homogenization optics adjustment device of the laser ablation-based analysis system shown in FIG. 1, showing a maximum beam size position relative to the homogenization optics adjustment device. [Figure 3A] FIG. 2C is a schematic isometric view of a square microlens array that can be used in the homogenizing optical system shown in FIGS. 2A-2C. [Figure 3B] FIG. 2C is a schematic isometric view of a fly's eye microlens condenser that can be used in the homogenizing optical system shown in FIGS. 2A-2C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Aspects of the present disclosure are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof and which show, by way of example, features. Features may, however, be embodied in many different forms and should not be construed as being limited to the combinations set forth herein. Rather, these combinations are provided so that this disclosure will be thorough and complete, and will fully convey its scope.

[0006] The current state of the art for the laser ablation portion of laser ablation based spectroscopy systems has been the use of two fly's eye homogenization (lens set) optics (e.g., used in pairs) to homogenize the laser beam. This beam homogenization method has only been used in 193 nm excimer-based (i.e., ultraviolet (UV) lasers using compounds such as rare gases, halogens, etc. as the laser medium) laser ablation systems, and has only been shown to work in high energy systems, e.g., laser ablation systems manufactured by Teledyne, Coherent, or Applied Spectra. Each of these companies is seen to use the dual fly's eye homogenization method in their systems. None have implemented a method to control the parameters of the laser beam by moving one of the devices and thus change the operating parameters of the system.

[0007] In the process of developing high energy ablation systems, it became clear that there are at least two main use cases desired by customers: one is to generate very large ablation spots at moderate energy densities, and the other is to generate very high energy densities or fluences at relatively small ablation spots. In optics, the fluence F, e.g., of a laser pulse, is the light energy delivered per unit area. Its most common unit is J / cm 2 (Joules per square centimeter). In an attempt to achieve very high energy densities while meeting the requirements for a large beam spot, it was discovered that in one embodiment it is possible to selectively increase or decrease the energy density at the sample by moving the first of two homogenizing optics in the system beam train. In one embodiment, this optical adjustment system can be motorized. Such a motorized adjustment system can be controllable via software and can have at least two (e.g., position / energy density) modes.

[0008] From a purely optical standpoint, the concept may be considered similar to an adjustable telescope. However, the use of movable optics to selectively increase or decrease energy density has not previously been employed in laser ablation for mass spectrometry, nor is there any evidence that such adjustable optics have been used in ablation, photoetching, or micromachining in general.

[0009] (Example) 1 shows a laser ablation-based analytical system 100 according to an exemplary embodiment of the present disclosure. The laser ablation-based analytical system 100 includes an ablation system 105 for ablating a target (not shown) of a sample material, a spectrometer 118 (e.g., an optical emission spectrometry system (OES) or a mass spectrometry system (MS)) that allows chemical analysis of the laser ablated sample (e.g., a sample ablated using the ablation system 105), and a computing system 120 that controls the operation of the entire system 100. The ablation system 105 includes a laser source 110 (e.g., an excimer laser), a pair of homogenization optics 112 (a first homogenizer 112A and a second homogenizer 112B), a homogenization optics adjustment device 114, and a beam adjustment optics 116 (e.g., a reflective or partially reflective surface and / or a window for reducing aberrations and / or expanding the beam). An example of an overall laser ablation based analytical system is shown in U.S. Patent Publication No. 2019 / 0371590A1, the contents of which are incorporated herein by reference. This disclosure focuses on the ablation system 105. Although the ablation system 105 is shown as part of the laser ablation based analytical system 100, it should be understood that the ablation system 105 may be used separately, may be used to ablate materials other than the sample material being analyzed, and / or may not be used in conjunction with a laser ablation based analytical system. In one embodiment, the spectrometer 118 may be configured to receive and analyze the material ablated by the laser.

[0010] The first homogenizer 112A, which initially receives the laser beam of the ablation system 105, may be in the form of a first microlens array, and the second homogenizer 112B, which initially receives the laser beam refracted by the first homogenizer 112A, may be in the form of a second microlens array. In one embodiment, the first microlens array is configured similarly to the second microlens array. In one embodiment, a given first homogenizer 112A and / or a given second homogenizer 112B may be in the form of a square microlens array 112(1) (e.g., a two-dimensional array of microlenses extending laterally and vertically) as shown in FIG. 3A. In one embodiment, a given first homogenizer 112A and / or a given second homogenizer 112B may be in the form of a fly's eye microlens array 112(2) (e.g., a monolithic assembly of double-sided cylindrical microlenses arranged in a one-dimensional array) as shown in FIG. 3B. It should be understood that other microlens array configurations (eg, a hexagonal array of microlenses, or a rectangular array of microlenses) are possible and within the scope of this disclosure.

[0011] The first homogenizer 112A and the second homogenizer 112B can be movably mounted relative to one another (e.g., at least one of the first homogenizer 112A or the second homogenizer 112B is selectively movable relative to the other) as shown in FIGS. 2A-2C. Such selective movement of at least one of the first homogenizer 112A or the second homogenizer 112B relative to the other can be achieved using a homogenization optics adjustment device 114. The homogenization optics adjustment device 114 can take the form of a mechanically adjustable conveyance device (e.g., rack and pinion, slide mount, etc.). In one embodiment, the homogenization optics adjustment device 114 can include fixtures (not shown) for each of the first homogenizer 112A and the second homogenizer 112B and an adjustment mechanism (not shown) for selectively moving the first homogenizer 112A or the second homogenizer 112B relative to one another. In one embodiment, the homogenization optics adjustment device 114 can precisely move the first homogenizer 112A axially (parallel) to the laser beam. The laser beam (not labeled) emitted by the laser source 110 is directed to the pair of homogenization optics 112, where the size of the laser beam can be adjusted (described in more detail below) before passing through optional beam adjustment optics 116 and finally hitting the sample or other material to be ablated. Figures 2A-2C respectively show the confocal position, minimum beam size position, and maximum beam size position of the pair of homogenization optics 112, as determined by the positioning of the homogenization optics adjustment device 114. In one embodiment, after passing through the homogenization optics 112 and optional beam adjustment optics 116, the laser beam can hit the material / sample and ablate the material / sample.

[0012] The homogenization optical adjustment device 114 of the ablation system 105 may be either motorized or non-motorized and may be repositioned (i.e., allowing the relative position between the first homogenizer 112A and the second homogenizer 112B to be changed). For example, moving the first homogenizer 112A may change the beam size (e.g., beam diameter or beam cross section) at the aperture plane, thereby allowing a higher fluence at the sample (ablation) site. By repositioning, the beam size may be adjusted to any size, as desired, within a range including a minimum beam size and a maximum beam size. Adjustment between the confocal beam size and the minimum beam size may be considered to operate as a first mode, in which the beam size (e.g., beam cross section) is smaller, but the energy density is higher than in the confocal position. Conversely, adjustment between the confocal beam size and the maximum beam size is considered to operate as a second mode, in which the beam size (e.g., beam cross-sectional area) is larger, but the energy density is smaller than in the confocal position. In another embodiment, the second homogenizer 112B can be moved by the homogenization optics adjustment device 114 (instead of or in addition to moving the first homogenizer 112A) to facilitate changing the fluence of the laser beam.

[0013] The energy density (e.g., fluence) of the laser beam spot generated by the combination of the laser source 110, a pair of homogenization optics 112 (first and second borogenizers 112A and 112B), and the homogenization optics adjustment device 114 of the ablation system 105 can generally be expressed by the following equation:

[0014]

number

[0015] Where: E = laser energy (e.g., mJ) A = beam cross-sectional area Energy density (e.g., J / cm 2 )

[0016] If the beam has a circular cross section, the energy density can be more specifically expressed by the following equation:

[0017]

number

[0018] Where: E = laser energy (e.g., mJ) D = beam diameter (e.g., cm) Energy density (e.g., J / cm 2 )

[0019] When the beam has a rectangular cross section (such as an excimer laser beam), the energy density can be more specifically expressed by the following formula:

[0020]

number

[0021] Where: E = laser energy (e.g., mJ) L = length of beam cross section (e.g. cm) W = length of beam cross section (e.g. cm) Energy density (e.g., J / cm 2 )

[0022] The laser ablation-based analysis system 100 can be controlled by a computing system 120. The computing system 120 has a processor configured to execute computer-readable program instructions (i.e., control logic) from a non-transitory carrier medium (e.g., a storage medium such as a flash drive, a hard disk drive, a solid-state disk drive, an SD card, an optical disk, etc.). The computing system 120 can be connected to various components of the analysis system via a direct connection or one or more network connections (e.g., a local area network (LAN), a wireless area network (WAN or WLAN), one or more hub connections (e.g., USB hub), etc.). For example, the computing system 120 can be communicatively coupled (e.g., wired or wireless) to the controllable elements of a given laser ablation-based analysis system 100 (e.g., the laser source 110, the homogenization optics adjustment device 114, the beam adjustment optics 116, and / or the spectrometer 118). The program instructions are executed by the processor, thereby enabling the computing system 120 to control the given laser ablation-based analysis system 100. In one implementation, the program instructions form at least a portion of a software program for execution by a processor. It should be understood that if ablation system 105 is used separately, it can be controlled by a computing system similar to computing system 120.

[0023] A processor provides processing capabilities to a computing system and may include any number of processors, microcontrollers, or other processing systems, as well as resident or external memory for storing data and other information accessed or generated by computing system 120. A processor is not limited to the materials from which it is formed or the processing mechanisms employed therein, and thus may be implemented via semiconductors and / or transistors (e.g., electronic integrated circuits (ICs)), etc.

[0024] The non-transitory carrier medium is an example of a device-readable storage medium that provides storage capabilities for storing various data related to the operation of the computing system 120, such as software programs, code segments, or program instructions, or other data that instruct the processor and other elements of the computing system to perform the techniques described herein. The carrier medium can be integrated with the processor, with standalone memory, or with a combination of both. The carrier medium can include removable and non-removable memory elements, such as, for example, RAM, ROM, flash (e.g., SD card, mini-SD card, micro-SD card), magnetic, optical, USB memory devices, and the like. In an embodiment of the computing system 120, the carrier medium can include removable ICC (Integrated Circuit Card) memory provided, for example, by a SIM (Subscriber Identity Module) card, a USIM (Universal Subscriber Identity Module) card, a UICC (Universal Integrated Circuit Card), and the like.

[0025] Computing system 120 may include one or more displays for displaying information to a user of computing system 120. In embodiments, the displays may include CRT (cathode ray tube) displays, LED (light emitting diode) displays, OLED (organic LED) displays, LCD (liquid crystal diode) displays, TFT (thin film transistor) LCD displays, LEP (light emitting polymer), or PLED (polymer light emitting diode) displays, etc., and may be configured to display text and / or graphical information, such as a graphical user interface. The displays may be backlit by a backlight so that they may be viewed in dark or other low light environments. The displays may include a touchscreen for receiving input (e.g., data, commands, etc.) from a user. For example, a user may operate computing system 120 by touching the touchscreen and / or by performing gestures on the touchscreen. In some embodiments, the touchscreen may be a capacitive touchscreen, a resistive touchscreen, an infrared touchscreen, combinations thereof, etc. Computing system 120 may further include one or more input / output (I / O) devices (e.g., a keypad, buttons, wireless input devices, thumbwheel input devices, track tick input devices, etc.) The I / O devices may include one or more audio I / O devices, such as a microphone, a speaker, etc.

[0026] Computing system 120 may also include a communications module that represents communications functionality that enables a computing device to send / receive data between different devices (e.g., components / peripherals) and / or across one or more networks. The communications module may represent various communications components and functionality, including, but not limited to, a browser, a transmitter and / or receiver, a data port, software interfaces and drivers, a networking interface, a data processing component, etc.

[0027] The one or more networks represent a variety of different communication paths and network connections that may be utilized individually or in combination to communicate between components of the laser ablation-based analysis system 100. Thus, the one or more networks may represent communication paths achieved using a single network or multiple networks. Additionally, the one or more networks are representative of a variety of different possible types of networks and connections, including, but not limited to, the Internet, an intranet, a personal area network (PAN), a local area network (LAN) (e.g., Ethernet), a wide area network (WAN), a satellite network, a cellular network, a mobile data network, wired and / or wireless connections, and the like. Examples of wireless networks include, but are not limited to, networks configured for communication according to one or more standards of the Institute of Electrical and Electronics Engineers (IEEE), such as the 802.11 or 802.16 (Wi-Max) standards, the Wi-Fi standard promulgated by the Wi-Fi Alliance, the Bluetooth standard promulgated by the Bluetooth Special Interest Group, and the like. Wired communication via Universal Serial Bus (USB), Ethernet, serial connections, and the like are also contemplated.

[0028] The computing system 120 is described as including a user interface that can be stored in a memory (e.g., a carrier medium) and executed by a processor. The user interface represents functionality that controls the display of information and data to a user of the computing system via a display. In some implementations, the display is not integrated into the computing system, but instead can be connected externally using a universal serial bus (USB), Ethernet, serial connection, or the like. The user interface can provide functionality that allows a user to interact with one or more applications of the computing system by providing input (e.g., sample identity, desired dilution factor, standard identity, eluent identity / location, fluid addition flow rate, etc.) via a touch screen and / or I / O devices. For example, the user interface can generate an application programming interface (API) and expose functionality to an online dilution control module to configure the application to display on the display or in combination with another display. In an embodiment, the API can further expose functionality to configure the in-line dilution control module to enable a user to interact with the application to provide a desired dilution factor for an analysis by providing input via a touch screen and / or I / O devices.

[0029] In an implementation, the user interface may include a browser. The browser may enable a computing device to display and interact with content, such as web pages in the World Wide Web, web pages provided by a web server in a private network, etc. The browser may be configured in a variety of ways. The browser may be a web browser suitable for use on a fully resourced device with sufficient memory and processor resources (e.g., a smart phone, a personal digital assistant (PDA)).

[0030] In general, any of the functions described herein may be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or a combination of these implementations. Terms such as "module" and "function" as used herein generally refer to software, firmware, hardware, or a combination thereof. Communication between components in the laser ablation-based analysis system 100 may be, for example, wired, wireless, or some combination thereof. The program code may be stored in one or more device-readable storage media, an example of which is a non-transitory carrier medium associated with a computing system.

[0031] Although the subject matter of the present disclosure has been described in terms specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. a laser source generating a laser beam; a set of homogenizing optics including a first homogenizer and a second homogenizer, the homogenizing optics receiving the laser beam; a homogenization optical system adjustment device having the homogenization optical system mounted thereon; Equipped with the homogenization optical system adjustment device selectively adjusts a position of at least one of the first homogenizer or the second homogenizer to change a beam size of the laser beam; a change in the beam size of the laser beam changes the fluence of the laser beam, the laser beam being configured to pass through the first homogenizer and the second homogenizer to ablate material. Ablation system.

2. The beam size is adjustable to any size within a range including a minimum beam size and a maximum beam size. The ablation system of claim 1 .

3. The position of the first homogenizer is adjustable. The ablation system of claim 1 .

4. the first homogenizer and the second homogenizer each include a microlens array; The ablation system of claim 1 .

5. the ablation system is incorporated into a laser ablation based analytical system, the laser ablation based analytical system including a spectrometer, the spectrometer configured to receive and analyze the ablated material. The ablation system of claim 1 .

6. the homogenization optics adjustment device is configured to selectively adjust a position of at least one of the first homogenizer and the second homogenizer to increase a beam cross-sectional area of ​​the laser beam and correspondingly reduce a fluence of the laser beam. The ablation system of claim 1 .

7. a laser source generating a laser beam; a set of homogenizing optics including a first homogenizer and a second homogenizer, the homogenizing optics receiving the laser beam; a homogenization optical system adjustment device including the first homogenizer and the second homogenizer; Equipped with the homogenization optical system adjustment device selectively adjusts a position of at least one of the first homogenizer or the second homogenizer to change a beam cross section of the laser beam; the laser beam is configured to ablate the sample after passing through the first homogenizer and the second homogenizer; Ablation system.

8. The beam cross section is adjustable within a range including a minimum beam cross section and a maximum beam cross section. The ablation system of claim 7.

9. The position of the first homogenizer is adjustable. The ablation system of claim 7.

10. At least one of the first homogenizer or the second homogenizer includes a microlens array. The ablation system of claim 7.

11. The ablation system is incorporated into a laser ablation-based analytical system. The ablation system of claim 7.

12. the laser ablation based analytical system includes a spectrometer, the spectrometer configured to receive and analyze the ablated sample; The ablation system of claim 11.

13. the homogenization optics adjustment device is configured to selectively adjust a position of at least one of the first homogenizer and the second homogenizer to increase the beam cross-section of the laser beam and correspondingly reduce the fluence of the laser beam. The ablation system of claim 7.

14. the homogenization optics adjustment device is configured to selectively adjust a position of at least one of the first homogenizer and the second homogenizer to reduce the beam cross-section of the laser beam and correspondingly increase the fluence of the laser beam. The ablation system of claim 7.

15. a laser source generating a laser beam; a set of homogenizing optics including a first homogenizer and a second homogenizer, the homogenizing optics receiving the laser beam; a homogenization optical system adjustment device including the first homogenizer and the second homogenizer; a spectrometer configured to receive and analyze the ablated material; Equipped with the homogenization optical system adjustment device selectively adjusts a position of at least one of the first homogenizer or the second homogenizer to change a beam size of the laser beam; the laser beam is configured to ablate the material after passing through the first homogenizer and the second homogenizer. Laser ablation-based analytical system.

16. the beam size of the laser beam is adjustable within a range including a minimum beam size and a maximum beam size; 16. The laser ablation-based analysis system of claim 15.

17. the first homogenizer and the second homogenizer each include a microlens array; 16. The laser ablation-based analysis system of claim 15.

18. The microlens array comprises either a square microlens array or a fly's eye microlens array.

20. The laser ablation-based analysis system of claim 17.

19. the homogenization optics adjustment device is configured to selectively adjust a position of at least one of the first homogenizer and the second homogenizer to increase the beam size of the laser beam and correspondingly reduce the fluence of the laser beam.

16. The laser ablation-based analysis system of claim 15.

20. the homogenization optics adjustment device is configured to selectively adjust a position of at least one of the first homogenizer and the second homogenizer to reduce the beam size of the laser beam and correspondingly increase the fluence of the laser beam.

16. The laser ablation-based analysis system of claim 15.

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