Target metrology for EUV light sources

Abstract

Disclosed are apparatus and methods for aligning a target comprised of a target material with a conditioning beam provided to condition the target by changing the target's shape, mass distribution, etc., where the conditioning beam includes structured light in the form of a non-uniform distribution of propagation modes, such as polarization modes, across the spatial modes of the target.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. patent application Ser. No. 63 / 058,987, filed July 30, 2020, entitled "STRUCTURED BEAM FOR EUV LIGHT SOURCE TARGET CONDITIONING WITH FEATURE FOR SELF-MONITORING OF ALIGNMENT," and U.S. patent application Ser. No. 63 / 212,793, filed June 21, 2021, entitled "EUV LIGHT SOURCE TARGET METROLOGY," each of which is incorporated by reference in its entirety into this specification.

[0002] This disclosure relates to light sources that produce extreme ultraviolet light by excitation of a target material, and in particular to measurement, eg, detection, of the target material within such light sources. [Background technology]

[0003]

[0003] Extreme ultraviolet ("EUV") light, for example, electromagnetic radiation having a wavelength of approximately 50 nm or less (sometimes also called soft x-ray), including light with a wavelength of about 13 nm, is used in photolithography processes to create extremely small features in and on substrates, such as silicon wafers.

[0004]

[0004] Methods for generating EUV light include, but are not limited to, converting the physical state of a target material into a plasma state. The target material includes elements having emission lines in the EUV range, such as xenon, lithium, or tin. In one such method, often referred to as laser-produced plasma ("LPP"), the required plasma is generated by irradiating the target material, for example in the form of droplets, streams, or clusters of the target material, with an amplified light beam, which may be referred to as a drive laser. For this process, the plasma is typically generated in a closed vessel, such as a vacuum chamber, and is monitored using various types of metrology.

[0005]

[0005] CO2 amplifiers and lasers that output an amplified light beam at a wavelength of about 10600 nm can offer certain advantages as a driving laser for irradiating a target material in an LPP process. This may be particularly true for certain target materials, such as materials that contain tin. For example, one advantage is the ability to provide a relatively high conversion efficiency between the driving laser input power and the output EUV power.

[0006]

[0006] In an EUV light source, EUV may be generated in a multi-step process in which a target, e.g., a droplet, is bombarded before reaching the irradiation site by one or more pulses that condition the target for eventual phase transformation at the irradiation site. Conditioning in this context may include changing the shape of the droplet, e.g., flattening the droplet, or changing the distribution of the droplet, e.g., at least partially dispersing some of the droplet as a mist, or even a partial phase change. For the purposes of this disclosure, these pulses that are preliminary to the main heating pulse are referred to as target conditioning beams, whether generated by the main driving laser or a separate laser.

[0007]

[0007] Also, as alluded to above, as a result of conditioning, the droplet of target material undergoes preliminary physical changes to irradiation by the main pulse, including a change in shape and a change in mass distribution. A mass of target material may be referred to as a droplet before conditioning and as a target after at least one conditioning. As used herein, "droplet" refers to the mass of target material before conditioning, while target refers to the mass of target material both before and after conditioning, and a droplet is a type of target unless the context indicates otherwise.

[0008]

[0008] One objective in efficient generation of EUV light is to achieve proper relative positioning of the conditioning beam and the target. This relative positioning is also referred to as alignment of the conditioning beam and the target. In general, for efficient and debris-minimized operation of the light source, it is important to align the target and conditioning beam within a few micrometers. In general, the alignment condition is determined by determining the position of the beam, determining the position of the target, and taking the difference. Thus, much effort has been put into determining the position of the target. For example, U.S. Patent No. 7,372,056, entitled "LPP EUV Plasma Source Material Target Delivery System," filed May 13, 2008, discloses the use of a droplet detection radiation source and a droplet radiation detector to detect droplet detection radiation reflected from droplets of target material. U.S. Patent No. 8,158,960, filed April 17, 2012, entitled "Laser Produced Plasma EUV Light Source," discloses the use of a droplet position detection system that may include one or more droplet imagers that provide an output indicative of the position of one or more droplets, e.g., relative to an irradiation area. The imagers may provide this output to a droplet position detection feedback system that may calculate, e.g., a droplet position and trajectory, and from the droplet position and trajectory, a droplet error. The droplet error may then be provided as an input to a controller that may provide, e.g., position, direction, and / or timing correction signals to a system to control a radiation source timing circuit and / or to control a beam position and shaping system, e.g., to change the position and / or focusing power of light pulses being delivered to the irradiation area.See also U.S. Patent No. 9,241,395, filed January 19, 2016, entitled "System and Method for Controlling Droplet Timing in an LPP EUV Light Source," and U.S. Patent No. 9,497,840, filed November 15, 2016, entitled "System and Method for Creating and Utilizing Dual Laser Curtains from a Single Laser in an LPP EUV Light Source."

[0009]

[0009] All patent applications, patents, and publications cited in this specification are incorporated herein by reference in their entirety, except for any definitions, subject matter disclaimers or disclaimers, and except to the extent that the incorporated material is not inconsistent with an explicit disclosure in this specification, in which case the language in the present disclosure will control.

[0010]

[0010] In some systems, the conditioning pulse reflected from the target is used to determine the location of the target in space by collecting the reflected light and imaging it on a sensor. In other systems, a secondary light source is used in addition to the conditioning pulse laser to illuminate the target, and a camera is positioned to image the illuminated target. This system introduces the challenge that the measurement does not directly determine the location of the droplet relative to the conditioning laser beam itself, but only relative to the camera. Therefore, an additional step is required to relate the reference frame of the measurement system to the reference frame of the target conditioning beam or heating laser. This has the disadvantage of trying to determine a small quantity as the difference between two relatively large quantities.

[0011]

[0011] Therefore, it is important to determine the relative position of the adjustment laser beam and the target material that the laser beam will hit. In existing technology, the adjustment laser beam and the target position are measured separately, and then the difference between the two large numbers is taken to obtain a small number. As a result, the accuracy is affected by noise and optical-mechanical drift between the subsystems that measure the two positions. This leads to inaccurate measurement results at high frequencies due to noise, and at high frequencies due to drift.

[0012] Therefore, there is a need for a target-to-beam alignment system that avoids these drawbacks. Summary of the Invention

[0013]

[0013] The following presents a brief summary of one or more embodiments in order to provide a basic understanding of the embodiments. This summary is not an extensive overview of all possible embodiments, and is not intended to identify key or critical elements of all embodiments or to limit the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description presented below.

[0014]

[0014] According to one aspect of the embodiment, an apparatus and method are disclosed for aligning a target with a conditioning beam, where the conditioning beam includes structured light or radiation having a non-uniform distribution of properties such as polarization across and intertwined with transverse spatial modes, thereby enabling information about the interaction of the target with the conditioning beam to be recovered, including a direct measurement of the position of the target material within the spatial mode of the conditioning beam. This involves only a single coordinate reference frame, instead of a transformation between two reference frames that must be calibrated to match.

[0015] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic, not to scale, diagram of an overall broad concept of a laser-produced plasma EUV radiation source system. [Diagram 2]

[0017] 1 is a schematic, not to scale, diagram of a target material measurement system; [Figure 3A]

[0018] FIG. 3 illustrates a particular targeting principle in a system such as that shown in FIGS. 1 and 2. [Figure 3B] FIG. 3 illustrates a particular targeting principle in a system such as that shown in FIGS. 1 and 2. [Figure 4A]

[0019] FIG. 2 illustrates certain operating principles of a target / adjustment beam alignment system according to an aspect of an embodiment. [Figure 4B]

[0020] FIG. 2 illustrates certain operating principles of a target / adjustment beam alignment system according to an aspect of an embodiment. [Figure 5A]

[0021] 1 is a schematic diagram, not to scale, illustrating certain operating principles of a target / adjustment beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 5B]

[0022] 1 is a schematic diagram, not to scale, illustrating certain operating principles of a target / adjustment beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 5C]

[0023] 1 is a schematic diagram, not to scale, illustrating certain operating principles of a target / adjustment beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 6A]

[0024] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 6B]

[0025] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 6C]

[0026] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 7A]

[0027] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 7B]

[0028] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 7C]

[0029] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 7D]

[0030] FIG. 8 is an example diagram of an imager that may be used in the embodiment of FIGS. 7A-7C. [Figure 7E] FIG. 4 is an illustration of an imager that may be used in the embodiments of FIGS. 7A-7C. [Figure 8A]

[0031] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 8B]

[0032] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 8C]

[0033] 1 is a schematic, not to scale, illustration of a target / conditioning beam alignment system in accordance with an aspect of an embodiment; FIG. [Figure 9]

[0034] 1 is a flow chart illustrating a mode of operation of a target / conditioning beam alignment system in accordance with an aspect of an embodiment. [Figure 10]

[0035] 1 is a flow chart illustrating a mode of operation of a target / conditioning beam alignment system in accordance with an aspect of an embodiment. [Figure 11]

[0036] 1 is a flow chart illustrating a mode of operation of a target / conditioning beam alignment system in accordance with an aspect of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017]

[0037] Further features and advantages of the subject matter of the present disclosure, as well as the structure and operation of various embodiments of the subject matter of the present disclosure, are described in detail below with reference to the accompanying drawings. It should be noted that the subject matter of the present disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings contained herein.

[0018]

[0038] Various embodiments will now be described with reference to the drawings, in which like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate a thorough understanding of the embodiments. However, it may be apparent that in some or all instances, any of the embodiments described below can be practiced without adopting the specific design details described below.

[0019]

[0039] Referring initially to FIG. 1, a schematic diagram of an exemplary EUV radiation source, e.g., a laser-produced plasma EUV radiation source 10, is shown in accordance with one aspect of an embodiment of the subject matter of the present disclosure. As shown, the EUV radiation source 10 may include a pulsed or continuous laser source 22, which may be a pulsed gas discharge CO2 laser source that generates a radiation beam 12 generally at a wavelength less than 20 μm, e.g., in the range of about 10.6 μm to about 0.5 μm or less. The pulsed gas discharge CO2 laser source may provide DC or RF excitation and operate at high power and high pulse repetition rates. The EUV radiation source 10 may also include one or more modules, such as a conditioned laser 23 that emits a beam 25 of conditioned radiation as described above.

[0020]

[0040] The EUV radiation source 10 also includes a target delivery system 24 that delivers the target material in the form of liquid droplets or a continuous liquid stream. In this example, the target material is liquid, but it could be, for example, solid. The target material could be comprised of tin or a tin compound, but other materials could be used. In the illustrated system, the target material delivery system 24 introduces droplets 14 of the target material inside a vacuum chamber 26 that leads to an irradiation region 28 where the target material can be irradiated to generate a plasma. In some cases, an electric charge is applied to the target material to allow steering the target material towards or away from the irradiation region 28. It should be noted that, as used herein, the irradiation region is the region where the target material irradiation takes place, even when irradiation is not actually taking place. The EUV light source may also include a beam focusing and steering system 32.

[0021]

[0041] In the illustrated system, the components are arranged such that the droplets 14 move in a generally horizontal direction. The direction from the laser source 22 towards the illumination region 28, i.e., the nominal propagation direction of the beam 12, may be considered the Z-axis. The path that the droplets 14 take from the target material delivery system 24 to the illumination region 28 may be considered the X-axis. Thus, the diagram in FIG. 1 is perpendicular to the XZ plane. Also, while a system is illustrated in which the droplets 14 travel in a substantially horizontal direction, one skilled in the art will appreciate that other configurations may be used in which the droplets travel vertically or at an angle between 90 degrees (horizontal) and 0 degrees (vertical) inclusive with respect to gravity.

[0022]

[0042] EUV radiation source 10 may also include an EUV source controller system 60, and may also include a laser firing control system 65, along with beam steering system 32. EUV radiation source 10 may also include a detector, such as a target position detection system, which may include, for example, one or more droplet imagers 70, that generate an output indicative of the absolute or relative position of the target droplet with respect to irradiation region 28 and provide this output to target position detection feedback system 62.

[0023]

[0043] The target position detection feedback system 62 may use the output of the droplet imager 70 to calculate the target position and trajectory, from which the target error may be calculated. The target error may be calculated on a droplet-by-droplet basis, or on an average, or on some other basis. The target error may then be provided as an input to the light source controller 60. In response, the light source controller 60 may generate and provide control signals, such as laser position, direction, and timing correction signals, to the laser beam steering system 32. The laser beam steering system 32 may use the control signals to change the position and / or focusing power of the laser beam focal point within the chamber 26. The laser beam steering system 32 may also use the control signals to change the geometry of the interaction of the beam 12 with the droplet 14. For example, the beam 12 may strike the droplet 14 off-center or at an angle of incidence other than head-on.

[0024]

[0044] 1, the target material delivery system 24 may include a target delivery control system 90. The target delivery control system 90 may be operable in response to a signal, such as the target error described above or some amount derived from the target error provided by the system controller 60, to adjust the path of the target droplets 14 through the irradiation region 28. This may be accomplished, for example, by repositioning the point at which the target delivery mechanism 92 releases the target droplets 14. Thus, the droplet release point may be repositioned by tilting the target delivery mechanism 92 or by offsetting the target delivery mechanism 92. The target delivery mechanism 92 extends into the chamber 26, and the target material and a source of gas are provided externally to place the target material in the target delivery mechanism 92 under pressure.

[0025]

[0045] Continuing with reference to FIG. 1, the radiation source 10 may also include one or more optical elements. In the following discussion, the collector 30 is used as an example of such an optical element, but the discussion also applies to other optical elements. The collector 30 may be a normal incidence reflector, for example realized as a multi-layer mirror (MLM) made by depositing multiple pairs of Mo / Si layers on a substrate with an additional thin barrier layer, e.g., B4C, ZrC, Si3N4 or C, deposited at each interface to effectively block thermally induced interlayer diffusion. The collector 30 may be in the shape of an oblong with a central aperture that allows the laser radiation to pass through and reach the illumination region 28. Collector 30 may, for example, be elliptical in shape with a first focal point at illumination region 28 and a second focal point at a so-called midpoint 40 (also referred to as intermediate focus 40), in which case EUV radiation may be output from EUV radiation source 10 and input to, for example, an integrated circuit lithography scanner or stepper 50, which uses the radiation to process a silicon wafer workpiece 52 in a known manner, for example with a reticle or mask 54. Silicon wafer workpiece 52 is then additionally processed in a known manner to obtain an integrated circuit device.

[0026]

[0046] As previously mentioned, one droplet detection metrology utilizes dark field illumination where backscatter from a target passing through a laser curtain is focused near the primary focus. The metrology device detects a droplet traversing a particular location in space and triggers the system control to enable all subsequent sequences to generate EUV. This is shown diagrammatically in FIG. 2, where a droplet detection controller 122 causes a droplet illumination module 124 to illuminate a droplet 14. A droplet detection module 126 detects radiation backscattered from the droplet, enabling the droplet detection controller 122 to determine the location of the droplet 14.

[0027]

[0047] Also, as mentioned above, generally as shown in Figure 3A, in the reference coordinate system, Z is the direction in which the laser beam 12 propagates, which is also the direction from the collector 30 to the irradiation site 110 and the EUV intermediate focus. X is in the droplet propagation plane. Y is orthogonal to the XZ plane. To make this a right-handed coordinate system, the trajectory of the droplet 14 is considered to be in the -X direction.

[0028]

[0048] The main components of the target alignment error are ΔX and ΔY, as shown in Figure 3B. These errors typically need to be kept below about 5um. Due to the relatively long Rayleigh length of the laser focus, errors in the Z direction are less critical and can be tolerated up to 100μm or worse.

[0029]

[0049] The X position error ΔX is mainly the result of timing errors, i.e., the timing of the laser firing, assuming a constant droplet velocity. Correction of the timing error can be very well achieved by detecting the time when the droplet crosses the laser curtain 115 in the vicinity of the illuminated site 110 in the illuminated area. This measurement can be done even when the laser is in operation, since the laser curtain 115 is provided by a separate laser source and can therefore always be on. Also, measurements performed using the laser curtain 115 are relatively tolerant to misalignments in Y, Z, since the curtain is made wide in the YZ plane. However, the determination of ΔX and Y needs improvement.

[0030]

[0050] To determine the (X,Y) error (X,ΔY), it is possible to use the reflection of the target conditioning beam 12 from the droplet 14 and a fast detector. The fast detector can be any suitable type of detector, for example an imaging detector or a quadrant detector. However, an imaging detector can only measure the position of the droplet relative to the imaging system geometry and the beam, as desired. When the target conditioning beam hits the droplet, the droplet scatters its light nearly isotropically in all directions that can be imaged by the camera. However, all that can be determined from this interaction is that enough of the pulse hit the droplet to scatter some light, and where the resulting image is located in the image plane of the imaging system. What is missing is the exact position of the target conditioning beam relative to the imaging system. A measurement of the position of this conditioning beam gives the droplet position, which must be combined with a second measurement of the beam positioning to obtain the droplet position in or relative to the beam, which is prone to error.

[0031]

[0051] In principle it is also possible to use a separate illuminator, such as the laser curtain 115 used for arrival time, to measure the Y position of the droplet. This requires the use of a high frame rate imaging 2D detector (camera) to resolve the position, whereas arrival timing only requires a non-imaging scattered light detector.

[0032]

[0052] According to aspects of the embodiment, the above objectives are achieved using structured light. Structured light refers to the ability to tailor (structure) light in several properties, such as amplitude, phase, and polarization, and combine the properties of light in an inseparable sense with the spatial properties of the beam ("classically entangled"). For example, a moving electromagnetic plane has E and B components. Adding these components with various amplitude and phase weightings results in polarization. At the same time, the magnitude of E at each point in the plane determines the transverse spatial mode. A vector state refers to a state in which the polarization pattern is unevenly distributed across the transverse spatial modes, in which the transverse spatial modes and polarization are classically entangled, i.e., inseparable. See C. Rosales-Guzman et al., "A review of complex vector light fields and their applications," J. Opt. 20 123001 (2018). The non-separable nature of cylindrically polarized vector beams is used to enable two-dimensional real-time sensing of fast moving objects. These systems rely on the object to perturb the spatial dependence of the beam but not its polarization. The required information about the beam and object is recovered by relating the resulting spatial modulation to the overall polarization state through the classically entangled modal structure of the beam.

[0033]

[0053] The Schmidt form of the field E(ρ,z) has measurable Stokes parameters that can be written as s0, s1, s2, and s3. When an opaque object traverses a non-uniformly polarized beam, the spatial and polarization patterns of the non-uniformly polarized beam change over time depending on the object's position, as expressed in central coordinates. Measurements of the Stokes parameters can be viewed as the solution of a non-linear algebraic system of four equations in two variables. Solving these equations provides information about the object's position in the spatial modes of the beam, or, if measurements of the time dependence are available, about the object's trajectory through the spatial modes of the beam.

[0034]

[0054] A mode converter as referred to herein intertwines a spatial polarization distribution with the spatial mode of a beam: rather than simply imprinting a polarization structure onto the input beam, the mode converter converts the input mode into some other spatial distribution of the electromagnetic field.

[0035]

[0055] If only linear polarization diversity is used to identify the location of a target in the conditioning beam, the mirror image degeneracy inherent in Stokes parameter measurements prevents unambiguous identification of the location. Assuming that the interaction occurs in the X, Y plane, both the X and Y positions of the target are always ambiguous until sufficient information about the trajectory is available that allows identifying the region the target is actually traversing. For example, in FIG. 4A, targets 430' and 430'' at the illustrated moment both provide reflected radiation with the same polarization direction and magnitude. Based on the understanding that the magnitude of the polarization is a function of radius and is zero at the center of the beam, the radial lines represent the polarization directions.

[0036]

[0056] One way to resolve the ambiguity is to use a continuous wave (CW) laser (which in some applications can be a quasi-continuous laser instead) to obtain time series measurements and then use the time dependence of the Stokes parameters to identify the location. For a radially polarized continuous beam, the interaction of the beam with the target can be conceptualized as shown in FIG. 4A. The polarization of the interacted light rotates from a negative angle to a positive angle, as shown in the inset, when the target 430′ crosses the half (e.g., the top half) of the radially polarized beam 435 traveling perpendicular to the plane of the figure. Meanwhile, the polarization of the interacted light rotates from a positive angle to a negative angle when the target 430″ crosses the other half (e.g., the bottom half) of the radially polarized beam 435. In other words, when the target 430′ crosses the beam 435 from left to right in the top half of the beam 435, first the angle of the polarization axis of the interacted light becomes negative, then zero, and then positive over time. When the target traverses the lower half, the time evolution of the interacted polarization is the exact opposite: it first becomes positive, then zero, and then negative. This information can be used to break the degeneracy and provide an unambiguous localization of the target's position relative to the beam.

[0037]

[0057] In this specification, including the description of all embodiments, and in the claims, terms such as interacted light or interacted beam refer to light or a beam that has interacted with a target in a way that changes the polarization structure of the beam, for example, by obscuration, reflection, or scattering. The term scattering is sometimes used generically to refer to interactions other than classical scattering.

[0038]

[0058] FIG. 5A illustrates a system that utilizes these principles. In FIG. 5A, a continuous wave laser 400 emits a beam 410. A mode converter 420 prepares the beam 410 in a radial polarization mode to form a converted beam 415. The mode converter 420 and other mode converters disclosed herein can be any suitable device for imparting entangled polarization states to the spatial modes of a beam. The mode converter can be, for example, a liquid crystal mode converter, a fused silica waveplate (s-plate for radial or azimuth polarization conversion) or a q-plate (for generating a light beam with optical orbital angular momentum (OAM) from a beam with a well-defined optical spin angular momentum (SAM), constructed of, for example, liquid crystal, polymer, or sub-wavelength gratings). The beam 415 impinges on and interacts with a target 430 traveling along a trajectory 450. The motion of the target 430 modulates the Stokes parameters of the traveling beam 417. A polarimetry module 460 splits the traveling beam 417 for projection into its linearly polarized components, in a known manner. The projections are measured simultaneously. The Stokes parameters of the time-varying beam are obtained by linear combination of the projection signals, allowing the instantaneous trajectory of the target 430 to be reconstructed.

[0039]

[0059] In the embodiment of Figure 5A, the mode converter 420 is positioned in the beam path between the CW (or quasi-continuous) laser 400 and the target 430. In other words, the mode converter 420 is external to the CW laser 400. According to another aspect of the embodiment, the mode converter can be positioned internal to the CW laser 400. This internal positioning is illustrated in Figure 5B, where the mode converter 420 is positioned within the CW laser 400, e.g., within the optical cavity of the CW laser 400.

[0040]

[0060] 5A and 5B use a bright field configuration in which light that has interacted with the target 430 reaches the polarimetry module 460. The system can also be implemented using dark field illumination in which the polarimetry module 460 is positioned to receive radiation 417 reflected from or scattered by the target 430. Such a configuration is shown in FIG. 5C.

[0041]

[0061] Thus, the time evolution of the signal provides information about the path of the target through the beam. According to one embodiment, in order to take advantage of this without introducing an additional reference frame of a separate measurement beam, the continuous beam is superimposed (i.e., made collinear) on the adjustment beam. The interaction of the beam with the target provides direct information about the offset of the target from the beam, which can be used to control the alignment of the beam with respect to the target, thereby optimizing the target adjustment process. The polarization of the interacting light provides a direct measurement of the alignment, rather than an indirect measurement. Measuring the changes caused by the interaction with the target requires only a polarization analyzer and a pair of "bucket" optical detectors, such as simple photodiodes. See S. Berg-Johansen et al., "Classically entangled optical beams for high-speed kinematic sensing," Optica 2, 864-868 (2015).

[0042]

[0062] Thus, according to an aspect of the embodiment, as shown in FIG. 6A, the beam 410 is converted into a structured beam by the mode converter 420 and made collinear with the conditioned beam 510 from the laser source 500 by the mirror 520 and the beam combiner 530 in a known manner. In this sense, structured light is added or introduced to the conditioned beam 510. The combined superimposed beam 535 interacts with the target 430 traveling along the trajectory 450 to produce a traveling beam 537 that includes the beam 520 that is modified by the interaction with the target 430. In other words, the motion of the target 430 modulates the Stokes parameters of the beam 520 component of the beam 537. The polarimetry module 460 measures the Stokes parameters of the beam 520 component of the beam 537 by splitting the beam 520 component for projection into its linearly polarized components in a known manner that allows the recovery of the trajectory of the target 430 through the combined beam 535.

[0043]

[0063] In the embodiment of Figure 6A, the mode converter 420 is positioned in the beam path between the CW laser 400 and the target 430. In other words, the mode converter 420 is external to the CW laser 400. According to another aspect of the embodiment, the mode converter can be positioned internal to the CW laser 400. This internal positioning is shown in Figure 6B, where the mode converter 420 is positioned within the CW laser 400, e.g., within the optical cavity of the CW laser 400.

[0044]

[0064] In some applications, it may be necessary or desirable to separate the beam 520 component of beam 537 within or prior to the polarimetry module 460. Thus, according to aspects of an embodiment, beam 520 may have a different wavelength than beam 510, and polarimetry module 460 may be adapted to evaluate only the polarization state of light having the wavelength of beam 510. Alternatively or additionally, beam 520 may be slightly offset from beam 510 in the path between beam combiner 530 and polarimetry module 460, and polarimetry module 460 may be adapted to evaluate only the polarization state of light at the position of beam 520 (spatial separation). Alternatively or additionally, polarimetry module 460 may be adapted to evaluate the polarization state of beam 520 when pulsed beam 510 is not generating light pulses (temporal separation).

[0045]

[0065] In the embodiment of Figures 6A and 6B, a bright-field configuration is used in which light intercepted by the target 430 reaches the polarimetry module 460. The principles disclosed herein are also applicable to a dark-field configuration in which the polarimetry module 460 is positioned to receive radiation that has interacted with the target 430. Such a configuration is shown in Figure 6C. Thus, according to aspects of the embodiment, as shown in Figure 6C, the beam 410 is converted into a structured beam by the mode converter 420 and made collinear with the conditioned beam 510 from the laser source 500 in a known manner by the mirror 520 and the beam combiner 530. In this sense, structured light is added or introduced to the conditioned beam 510. The motion of the target 430 modulates the Stokes parameters of the beam 520 components of the combined interacted beam 537. Polarimetry module 460 measures the Stokes parameters of beam 520 component of combined beam 537 by splitting it for projection into its linearly polarized components in a known manner that allows recovery of the trajectory of target 430 through combined beam 535. Again, wavelength or time separation may be used to extract beam 520 components of combined beam 537 to the extent necessary or desired. Separation may also be used in other embodiments disclosed herein as needed or desired.

[0046]

[0066] Pulses from pulsed lasers are generally too short to provide enough useful information about the target's trajectory to resolve the degeneracy of linear polarimetry. An analogy is the "picture" from a CW laser as opposed to the "snapshot" from a pulsed laser. When a time series is not available, one way to resolve the ambiguity inherent in pulsed lasers is to detect in which degenerate region the target is located, for example using an imaging detector or wavelength diversity in the degenerate region of the beam.

[0047]

[0067] In other words, when using pulsed lasers, it is generally possible to determine at best only partial trajectories that provide insufficient information about the rotation of the polarization vector to eliminate ambiguity in the target position. In a single sample, when measuring the polarization angle and the degree of polarization with the polarization angle, there is enough information to determine which of two possible positions the target occupies. If this process is considered to be taking place in the X,Y plane, then again X and Y are ambiguous at the same time. It is possible to resolve both of these ambiguities with another single measurement, for example using an imaging detector that is accurate enough to indicate whether the target is to the right or left of the center or above or below the center. This is a kind of parity ambiguity of the two possible positions + / -X and + / -Y. Additional measurements will eliminate this parity ambiguity.

[0048]

[0068] Therefore, according to another aspect of the embodiment, the vector properties of the beam are used to sense two possible positions of the target relative to the modal structure of the beam, and a conventional imaging configuration with a 1D or 2D array of detectors is used to remove the ambiguity of the instantaneous position relative to the modal structure of the beam.

[0049]

[0069] FIG. 7A shows a configuration in which a conditioned laser 500 emits a laser beam 510. The polarization mode of the laser beam 510 is transformed by a mode transformer 600. In this sense, structured light is added or introduced to the conditioned beam 510. The transformed beam 615 interacts with a target 430. The transformed interacted beam 617 is then split into beams 630 and 640 by a beam splitter 620. The Stokes parameters of a portion 630 of the interacted split beam 617 are measured by a polarimetry module 660 to identify the location of the target 430 with parity ambiguity. An imager 650 receives the other portion 640 of the interacted split light beam 617 to resolve the parity ambiguity of the instantaneous position of the target relative to the mode structure of the beam 615.

[0050]

[0070] In the embodiment of Figure 7A, the mode converter 600 is positioned in the beam path between the conditioned laser 500 and the target 430. In other words, the mode converter 600 is external to the conditioned laser 500. In accordance with another aspect of the embodiment, the mode converter can be positioned internal to the conditioned laser. This internal positioning is shown in Figure 7B, where the mode converter 680 is positioned within the laser 670, e.g., within the optical cavity of the laser 670.

[0051]

[0071] Again, the embodiment of Figures 7A and 7B uses a bright-field configuration in which light interacting with the target 430 reaches the polarimetry module 660 and imager 650. The principles disclosed herein are also applicable to a dark-field configuration in which the polarimetry module 660 and imager 650 are arranged to receive radiation reflected or scattered by the target 430. Such a configuration is shown in Figure 7C. The transformed beam 615 interacts with the target 430. A beam splitter 620 is arranged to receive the reflected or scattered beam 617. The beam splitter 620 splits the transformed, reflected or scattered beam 615 into beam 630 and beam 640. The Stokes parameters of the split reflected or scattered beam part 630 are measured by the polarimetry module 660 to identify the location of the target with parity ambiguity. The imager 650 receives the other part 640 of the scattered split light beam to remove the ambiguity of the instantaneous position of the target relative to the spatial mode structure of the beam.

[0052]

[0072] Imager 650 can be, for example, a one-dimensional array, such as one-dimensional array 650b of FIG. 7D, or a two-dimensional array, such as two-dimensional array 650c of FIG. 7E.

[0053]

[0073] Another way to resolve the ambiguity inherent when using pulsed lasers is to resolve its degeneracy using vector polarized beams that exploit the handedness of elliptically polarized light. In this approach, an azimuthal vector beam with a small circular / elliptical component is used. By analyzing the handedness of the circular component, the location of the target can be distinguished as up / down or right / left relative to the beam center without using a transit time series (e.g., with a single pulse). According to aspects of the embodiment, this is extended with a beam that has both vector and vortex diversity. Simultaneous polarization and angular momentum diversity with both vector and vortex properties allows for unambiguous association of any position in the mode with a unique polarization state. The orientation of the polarization principal axis distinguishes left from right, and handedness distinguishes up from down. See P. Lochab et al., “Robust laser beam engineering using polarization and angular momentum diversity,” Opt. Express 25, 17524-17529 (2017).

[0054]

[0074] Thus, as shown in FIG. 4B, the polarization states are mapped onto the Poincaré sphere using a technique similar to the latitude and longitude system used to locate points on the Earth. The coordinates of points across and within the Poincaré sphere are specified using two angle values ​​(azimuth and ellipticity) and a radius. The azimuth and ellipticity parameters are obtained from the polarization elliptical representation of the polarization states. The radius is specified by the degree of polarization of the light. The state mapped to the equator of the sphere is perfectly linearly polarized. The states mapped to values ​​of ±1 on the s3 axis are circularly polarized. All elliptical polarization states that are not linearly or circularly polarized are mapped to other regions of the sphere. Thus, light interacting with the target 430''' is right-hand elliptically polarized with a degree of ellipticity and tilt specified by its location.

[0055]

[0075] To resolve position ambiguity in two dimensions, a beam with both vector and vortex, or OAM, properties is used. Measuring the tilt of the interacted polarization ellipse locates the target relative to the laser mode, but with a parity ambiguity, and measuring the handedness of the polarization eliminates the parity ambiguity in the position measurement by determining which of two possible positions is correct.

[0056]

[0076] According to this approach, FIG. 8A shows a tuned laser 500 emitting a beam 510. A mode converter 700 converts the beam 510 into a beam 715 with diversity in both polarization and angular momentum. The converted beam 715 interacts with a target 430. An analyzer 710 positioned to receive a scattered beam 717 then identifies the orientation of the polarization principal axis to distinguish whether the target 430 was in the right or left hemisphere of the spatial modes of the beam 715, while using the handedness of the angular momentum to determine whether the target 430 was in the right or left hemisphere of the intertwined spatial modes of the beam 715.

[0057]

[0077] In the embodiment of Figure 8A, the mode converter 700 is positioned in the beam path between the tuned laser 500 and the target 430. In other words, the mode converter 700 is external to the tuned laser 500. In accordance with another aspect of the embodiment, the mode converter can be positioned internal to the tuned laser. This internal positioning is shown in Figure 8B, where the mode converter 720 is positioned within the laser 710, e.g., within the optical cavity of the laser 710.

[0058]

[0078] Again, the embodiments of Figures 8A and 8B use a bright-field configuration in which light that has interacted with the target 430 reaches the analyzer 710. The principles disclosed herein are also applicable to a dark-field configuration in which the polarimetric analyzer 710 is positioned to receive radiation backscattered from the target 430. Such a configuration is shown in Figure 8C.

[0059]

[0079] Additionally, other variations are possible, for example using a two-color vector beam for the adjustment beam to resolve ambiguities when making measurements with a single pulse of illumination, or using a hybrid approach in which a polarization-sensitive detector on the backscattered beam achieves some spatial discrimination through polarization and some spatial discrimination using spot displacement.

[0060]

[0080] Instead of using a full frame camera, the subject matter of this disclosure offers the possibility to inspect the target shape using only two photodiodes and process the image to extract image features that are sensitive to the alignment of the beam with the target. Some embodiments require at most two ports, or even a single port, in some schemes with light that is at least partially scattered in a direction opposite to the beam direction.

[0061]

[0081] The subject matter of this disclosure provides a vector beam approach for sensing the position of a target within a beam used for both metrology and target adjustment. The vector beam approach allows for direct connection of the coordinate systems of the adjustment beams, since the metrology vector beam providing the data for alignment measurements is the same beam or collinear with the adjustment beam, providing direct "laser-to-droplet" or "laser-to-target" measurements for control and optimization.

[0062]

[0082] In configurations where multiple conditioning lasers or laser beams are used, such as a separate target conditioning beam and a separate pedestal beam, each can be provided with its own target / beam alignment system as described above.

[0063]

[0083] FIG. 9 is a flow chart illustrating a procedure for aligning a target with a conditioning beam according to one aspect of an embodiment. In step S10, a conditioning beam is generated. At the same time, in step S20, a measurement beam is generated. The measurement beam is converted into a beam having structured radiation in step S30. In step S40, the conditioning beam and the converted measurement beam are combined, for example, by a beam combiner. In step S50, the combined beam is used to align the target. The interaction also changes the polarization state of the structured radiation. In step S60, the interacted beam is analyzed, and in step S70, data obtained from the analysis of the interacted beam is used to determine the alignment of the conditioning beam with the target. In step S80, the alignment of the conditioning beam with the target is controlled, for example, by bringing the conditioning beam and the target into a desired alignment state. This alignment can be achieved, for example, by providing control signals to the beam focusing and steering system 32 of FIG. 1.

[0064]

[0084] FIG. 10 is also a flow chart illustrating a procedure for aligning a target with a conditioning beam according to another aspect of the embodiment. As shown, in step S10, a conditioning beam is generated. In step S100, the conditioning beam is transformed by non-uniformly changing the polarization mode of the beam to obtain a structured beam. In step S110, the structured and transformed beam is used to condition a target, and the structured beam, i.e., a structured portion of the beam, interacts with and modifies this portion upon interaction. In step S120, the interacted beam is split. In step S140, a partial or full polarization of one of the beams resulting from the splitting is used as an image data source, e.g., a one-dimensional image data source. In step S130, a partial or full polarization of another beam resulting from the splitting is analyzed. In step S150, data obtained from the image analysis in step S140 and the polarization analysis in step S130 are used to determine the alignment of the conditioning beam with the target. In step S160, the alignment of the conditioning beam with the target is controlled, for example, by bringing the conditioning beam with the target into a desired alignment, which can be accomplished, for example, by providing control signals to beam focusing and steering system 32 of FIG.

[0065]

[0085] FIG. 11 is also a flow chart illustrating a procedure for aligning a target with a conditioning beam according to another aspect of an embodiment. As described above, a conditioning beam is generated in step S10. In steps S200 and S210, which may be performed in any order, a vector polarization transformation is performed on the conditioning beam (step S200) and an OAM (vortex polarization) transformation is performed on the conditioning beam (step 210). These steps result in a structured beam with non-uniform vector and vortex polarization. In step S220, the transformed beam interacts with a target. Then, in steps 230 and 240, which may be performed simultaneously or in any order, the polarization of the interacted beam is analyzed and the OAM of the interacted beam is analyzed, respectively. In step S250, data from the polarization analysis and the angular momentum analysis are used to determine the alignment of the beam with the target. In step S260, the alignment of the conditioning beam with the target is controlled, for example, by bringing the conditioning beam with the target into a desired alignment state. This alignment can be achieved, for example, by providing control signals to beam focusing and steering system 32 of FIG.

[0066]

[0086] The present disclosure is made with the aid of functional building blocks that illustrate the implementation of and relationships between specified functions. The boundaries of these functional building blocks are arbitrarily defined herein for convenience of description. Alternative boundaries can be defined so long as the specified functions and relationships between them are appropriately performed. For example, the control module functions can be divided among several systems or can be performed at least in part by an entire control system.

[0067]

[0087] The above description includes examples of one or more embodiments. Of course, it is not possible to describe every conceivable combination of components or methods for purposes of describing the foregoing embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to encompass all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, the term "comprises" is intended to be interpreted as a transitional term when used in the claims, so that to the extent the term "comprises" is used in either the detailed description or the claims, such term is intended to be as inclusive as "comprises." Furthermore, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is also contemplated unless expressly stated to be limited to the singular. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless otherwise stated.

[0068]

[0088] The embodiments can be further described using the following clauses. 1. An apparatus for aligning a target of target material with a beam of conditioned radiation, comprising: a source of structured conditioned radiation; an analyzer arranged to receive a beam of structured conditioned radiation generated from the beam of structured conditioned radiation after the beam of structured conditioned radiation interacts with a target, the analyzer adapted to analyze polarization of the interacted structured conditioned radiation to determine alignment of the beam of structured conditioned radiation with the target; An apparatus comprising: 2. The apparatus of claim 1, further comprising an alignment system that controls alignment of a source of structured conditioning radiation with a target based at least in part on the alignment determined by the analyzer. 3. The apparatus of claim 2, wherein the alignment system comprises a beam steering system. 4. The apparatus described in clause 1, wherein the source of structured conditioned radiation comprises a laser system comprising a laser configured to generate a beam of conditioned radiation and a module arranged to receive the beam of conditioned radiation and configured to add structured radiation having a spatially non-uniform polarization distribution to the beam of conditioned radiation. 5. The apparatus described in clause 4, wherein the module comprises a measurement laser system configured to generate a beam of structured radiation having a spatially non-uniform polarization distribution, and a beam combiner arranged to receive and combine the beam of conditioned radiation and the beam of structured radiation to form a combined beam. 6. An apparatus as described in clause 4, wherein the module comprises a mode converter arranged to convert the polarization mode of the conditioned radiation to generate a beam including structured radiation having a non-uniform linear polarization. 7. An apparatus as described in clause 6, wherein the mode converter is positioned to receive the beam of conditioned radiation from the laser. 8. The apparatus of claim 6, wherein the mode converter is disposed within an optical cavity of the laser. 9. An apparatus for determining alignment between a target of target material and a beam including conditioned radiation, comprising: a first laser system configured to generate a beam of conditioned radiation; a second laser system configured to generate a structured radiation beam having a spatially non-uniform polarization distribution; and a beam combiner arranged to receive and combine the beam of conditioned radiation and the beam of structured radiation to form a combined beam; an analyzer positioned to receive radiation from the combined beam after the combined beam interacts with the target, the analyzer adapted to analyze polarization of the combined beam; An apparatus comprising: 10. The apparatus of clause 9, wherein the first laser system configured to generate the beam of conditioned radiation includes a pulsed laser. 11. The apparatus of clause 9, wherein the second laser system configured to generate a beam of structured radiation comprises a continuous wave or quasi-continuous wave laser. 12. Apparatus according to clause 9, wherein the laser system configured to generate a beam of structured radiation comprises a continuous wave or quasi-continuous wave laser and a mode converter arranged to receive radiation from the continuous wave or quasi-continuous wave laser. 13. An apparatus for determining alignment of a target of target material with a beam of conditioning radiation, comprising: a laser system configured to generate a beam of conditioned radiation propagating in a first direction; a mode converter arranged to receive a beam of conditioned radiation from the laser system and convert a polarization mode of the conditioned radiation from the laser system to generate a beam of structured radiation propagating in a first direction; a beam splitter / combiner positioned to receive the structured radiation after the beam of structured radiation interacts with the target and to split the interacted radiation into at least a first beam and a second beam; an analyzer arranged to receive the first beam, the analyzer adapted to analyze a polarization of the first beam to obtain a first portion of information indicative of a position of the target relative to the beam of conditioning radiation; a detector positioned to receive the second beam, the detector adapted to use image information in the second beam to obtain a second portion of information indicative of a position of the target relative to the detector; a system arranged to receive a first portion of information and a second portion of information, the system being adapted to obtain a position of the target relative to the beam of conditioned radiation based on the first portion of information and the second portion of information; An apparatus comprising: 14. An apparatus for determining alignment of a target of target material with a beam of conditioning radiation, comprising: a laser system configured to generate a beam of conditioned radiation, the laser system including mode conversion means arranged to receive the conditioned radiation from the laser system and convert a vector polarization mode of the conditioned radiation and a spiral polarization mode of the conditioned radiation to obtain a structured radiation beam having a non-uniform vector polarization and a non-uniform spiral polarization; an analyzer arranged to receive the structured radiation beam after it has interacted with a target, the analyzer being adapted to analyze the polarization orientation of the scattered structured radiation and the handedness of the vortex polarization of the scattered structured radiation to obtain a position of the target relative to the beam of conditioned radiation; An apparatus comprising: 15. A method for aligning a target with a beam of conditioning radiation, comprising: generating a beam of conditioned radiation using a laser system; adding structured radiation having a spatially non-uniform polarization distribution to a beam of tailored radiation; impinging a beam of conditioned radiation having structured radiation on a target to interact with the target and generate interacted radiation; Analyzing the interacted radiation to determine an alignment state between the target and the adjustment beam; A method comprising: 16. The method of claim 15, further comprising controlling alignment of the beam of tailored radiation with the structured radiation and the target based on alignment conditions determined by analysis of the interacted radiation. 17. A method for aligning a target with a conditioning beam, comprising: generating a conditioned beam traveling in a first direction; generating a measurement beam; converting the metrology beam into a structured metrology beam having structured radiation; combining the conditioning beam and the structured metrology beam into a combined beam traveling in a first direction; impinging the combined beam on a target to interact with the target and generate interacted radiation; Analyzing the interacted radiation to determine an alignment state between the target and the adjustment beam; A method comprising: 18. The method of claim 17, wherein generating the conditioned beam includes generating the pulsed beam using a laser. 19. The method of claim 17, wherein generating the measurement beam includes using a continuous wave or quasi-continuous wave laser to generate a continuous or quasi-continuous beam. 20. A method for aligning a target with a conditioning beam, comprising: generating a conditioned beam; transforming the conditioned beam by changing a polarization mode of the conditioned beam by spatially non-uniformly intertwining one or more spatial polarization distributions with one or more spatial modes of the conditioned beam to obtain a structured beam; impinging the structured beam on a target to interact with the target and generate a beam of interacted radiation; splitting the interacted beam of radiation into at least a first beam and a second beam; acquiring image data from the first beam; Obtaining polarization data from the second beam; and determining alignment of the adjustment beam with the target using the image data and the polarization data; A method comprising: 21. A method for aligning a target with a conditioning beam, comprising: generating a conditioned beam; performing a vector polarization conversion on the conditioned beam and performing a vortex polarization on the conditioned beam, in any order, to obtain a structured beam having a non-uniform vector polarization and a non-uniform vortex polarization; impinging the interacted beam on a target to interact with the target and generate a beam of interacted radiation; performing, in any order or simultaneously, an analysis of vector polarization of the interacted beam and a analysis of vortex polarization of the interacted beam; Identifying beam and target alignment from analysis A method comprising:

Claims

1. 1. An apparatus for aligning a target of target material with a beam of conditioned radiation, comprising: a source of structured conditioned radiation; an analyzer arranged to receive the beam of structured conditioned radiation generated from the beam of structured conditioned radiation after the beam of structured conditioned radiation interacts with the target, an analyzer adapted to analyze polarization of the interacted structured conditioning radiation to determine alignment of the target with the beam of structured conditioning radiation; An apparatus comprising:

2. The apparatus of claim 1 , further comprising an alignment system that controls alignment of the source of structured conditioned radiation with the target based at least in part on the alignment determined by the analyzer.

3. The apparatus of claim 2 , wherein the alignment system comprises a beam steering system.

4. 2. The apparatus of claim 1, wherein the source of structured tailored radiation comprises a laser system comprising a laser configured to generate the beam of tailored radiation and a module arranged to receive the beam of tailored radiation, the module configured to add structured radiation having a spatially non-uniform polarization distribution to the beam of tailored radiation.

5. 5. The apparatus of claim 4, wherein the module comprises: a measurement laser system configured to generate a beam of structured radiation having a spatially non-uniform polarization distribution; and a beam combiner arranged to receive and combine the beam of tailored radiation and the beam of structured radiation to form a combined beam.

6. 5. The apparatus of claim 4, wherein the module comprises a mode converter arranged to convert a polarization mode of the conditioned radiation to generate a beam comprising structured radiation having a non-uniform linear polarization.

7. The apparatus of claim 6 , wherein the mode converter is positioned to receive the beam of conditioned radiation from the laser.

8. The apparatus of claim 6 , wherein the mode converter is disposed within an optical cavity of the laser.

9. 1. An apparatus for determining an alignment between a target of target material and a beam including conditioned radiation, the apparatus comprising: a first laser system configured to generate a beam of conditioned radiation; a second laser system configured to generate a beam of structured radiation having a spatially non-uniform polarization distribution; a beam combiner arranged to receive and combine said beam of conditioned radiation and said beam of structured radiation to form a combined beam; an analyzer positioned to receive radiation from the combined beam after it interacts with the target, the analyzer adapted to analyze polarization of the combined beam; An apparatus comprising:

10. The apparatus of claim 9 , wherein the first laser system configured to generate the beam of conditioned radiation comprises a pulsed laser.

11. The apparatus of claim 9 , wherein the second laser system configured to generate a beam of structured radiation comprises a continuous wave or quasi-continuous wave laser.

12. 10. The apparatus of claim 9, wherein the laser system configured to generate a beam of structured radiation comprises a continuous wave or quasi-continuous wave laser and a mode converter positioned to receive radiation from the continuous wave or quasi-continuous wave laser.

13. 1. An apparatus for determining alignment of a target of target material with a beam of conditioned radiation, comprising: a laser system configured to generate the beam of conditioned radiation propagating in a first direction; a mode converter arranged to receive the beam of conditioned radiation from the laser system and convert a polarization mode of the conditioned radiation from the laser system to generate a beam of structured radiation propagating in the first direction; a beam splitter / combiner positioned to receive the beam of structured radiation after it interacts with the target and to split the interacted radiation into at least a first beam and a second beam; an analyzer arranged to receive the first beam, the analyzer adapted to analyze a polarization of the first beam to obtain a first portion of information representative of a position of the target relative to the beam of conditioned radiation; a detector positioned to receive the second beam, the detector adapted to use image information in the second beam to obtain a second portion of information indicative of a position of the target relative to the detector; a system arranged to receive the first portion of information and the second portion of information, the system adapted to obtain a position of the target relative to the beam of conditioned radiation based on the first portion of information and the second portion of information; An apparatus comprising:

14. 1. An apparatus for determining alignment of a target of target material with a beam of conditioned radiation, comprising: a laser system configured to generate said beam of conditioned radiation, said laser system including mode conversion means arranged to receive the conditioned radiation from said laser system and convert a vector polarization mode of the conditioned radiation and a spiral polarization mode of the conditioned radiation to obtain a structured radiation beam having a non-uniform vector polarization and a non-uniform spiral polarization; an analyzer arranged to receive the structured radiation beam after it has interacted with the target, the analyzer adapted to analyze a polarization orientation of the scattered structured radiation beam and a handedness of the circular polarization of the scattered structured radiation beam to obtain a position of the target relative to the beam of conditioned radiation; An apparatus comprising:

15. 1. A method for aligning a target with a beam of conditioned radiation, comprising the steps of: generating said beam of conditioned radiation using a laser system; adding structured radiation having a spatially non-uniform polarization distribution to said beam of tailored radiation; impinging the beam of conditioned radiation having structured radiation on the target to interact with the target and generate interacted radiation; analyzing the interacted radiation to determine an alignment of the target with the beam; A method comprising:

16. 16. The method of claim 15, further comprising controlling an alignment of the beam of tailored radiation with the structured radiation and the target based on the alignment condition determined by analysis of the interacted radiation.

17. 1. A method for aligning a target with a conditioning beam, comprising: generating a conditioned beam; transforming the conditioned beam by changing a polarization mode of the conditioned beam by spatially non-uniformly intertwining one or more spatial polarization distributions with one or more spatial modes of the conditioned beam to obtain a structured beam; impinging the structured beam on the target to interact with the target and generate a beam of interacted radiation; splitting the interacted beam of radiation into at least a first beam and a second beam; acquiring image data from the first beam; acquiring polarization data from the second beam; and determining an alignment of the conditioning beam with the target using the image data and the polarization data; and A method comprising:

18. 1. A method for aligning a target with a conditioning beam, comprising: generating a conditioned beam; performing a vector polarization conversion on the conditioned beam and performing a circular polarization on the conditioned beam, in any order, to obtain a structured beam having a non-uniform vector polarization and a non-uniform circular polarization; impinging the interacted beam on the target to interact with the target and generate a beam of interacted radiation; performing, in any order or simultaneously, an analysis of vector polarization of the interacted beam and a analysis of vortex polarization of the interacted beam; determining an alignment of the beam with the target from the analysis; and A method comprising:

Images