Broadband irradiation coherence

Abstract

The tunable filter 102 may include an input focusing optic 104a, an output focusing optic 104b, a linear variable filter 106 disposed at the back focal plane of the input focusing optic 104a and the front focal plane of the output focusing optic 104b, an input angle scanning component 108a disposed at the front focal plane of the input focusing optic 104a and configured to receive an input beam 110, and an output angle scanning component 108b disposed at the back focal plane of the output focusing optic 104b. The input focusing optic 104a may receive the input beam 110 from the input angle scanning component 108a and direct the input beam 110 to the linear variable filter 106, the position of the input beam 110 on the linear variable filter 106 being selectable based on the angle of the input angle scanning component 108a. The output focusing optic 104b may receive a filtered beam 114 from the linear variable filter 106 and direct the filtered beam 114 to the output angle scanning component 108b.

Description

Technical Field

[0001] The present disclosure generally relates to the synchronization of broadband irradiation sources, and more particularly to the high-speed synchronization of coherent broadband irradiation sources using scanning optical components and linear variable filters.

Background Art

[0002] Cross-reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 62 / 971,982, filed on February 9, 2020, under 35 U.S.C. § 119(e), which is hereby incorporated by reference in its entirety.

[0003] Wavelength-variable light sources can provide illumination synchronized to one or more selected wavelengths within a given spectral range. However, typical wavelength-variable light sources may have limited ability to rapidly and precisely modify the brightness or spectrum of the synchronized irradiation beam. Furthermore, typical external wavelength-variable filters may have a low synchronization speed, a limited spectral width, or limited polarization requirements.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, it should be desirable to provide a system and method for resolving defects such as those identified above.

Means for Solving the Problems

[0006] According to one or more exemplary embodiments of the present disclosure, a wavelength-variable filter is disclosed. In an exemplary embodiment, the wavelength-variable filter includes an input focusing optical component. In another exemplary embodiment, the wavelength-variable filter includes an output focusing optical component. In another exemplary embodiment, the wavelength-variable filter includes a linear variable filter, and the filtering parameters of the linear variable filter are different based on the spatial position on the linear variable filter. In another exemplary embodiment, the linear variable filter is disposed at the rear focal plane of the input focusing optical component and the front focal plane of the output focusing optical component. In another exemplary embodiment, the wavelength-variable filter includes an input angle scanning component disposed at the front focal plane of the input focusing optical component to receive an input beam, the input focusing optical component receives the input beam from the input angle scanning component and directs the input beam to the linear variable filter. In another exemplary embodiment, the position of the input beam on the linear variable filter is selectable based on the angle of the input angle scanning component. In another exemplary embodiment, the wavelength-variable filter includes an output angle scanning component disposed at the rear focal plane of the output focusing optical component, the output focusing optical component receives the input beam as a filtered beam from the linear variable filter and directs the filtered beam to the output angle scanning component. In another exemplary embodiment, the output angle scanning component supplies the filtered beam as an output beam along an output path selectable based on the angle of the output angle scanning component.

[0007] A system is disclosed in accordance with one or more exemplary embodiments of the present disclosure. In one exemplary embodiment, the system includes two or more wavelength-variable filters. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an input focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an output focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes a linear variable filter, and the filtering parameters of the linear variable filter vary based on the spatial position on the linear variable filter, and the linear variable filter is disposed at the rear focal plane of the input focusing optical component and the front focal plane of the output focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an input angle scanning component disposed at the front focal plane of the input focusing optical component to receive an input beam, and the input angle scanning component receives the input beam from the input focusing optical component and directs the input beam to the linear variable filter. In another exemplary embodiment, the position of the input beam on the linear variable filter is selectable based on the angle of the input angle scanning component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an output angle scanning component disposed at the rear focal plane of the output focusing optical component, and the output focusing optical component receives the input beam as a filtered beam from the linear variable filter and directs the filtered beam to the output angle scanning component. In another exemplary embodiment, the output beams of all but the last of the two or more wavelength-variable filters are the input beams of the next wavelength-variable filter of the two or more wavelength-variable filters.

[0008] An irradiation system is disclosed in accordance with one or more exemplary embodiments of the present disclosure. In one exemplary embodiment, the irradiation system includes an irradiation source for generating an input beam. In another exemplary embodiment, the irradiation system includes a filtering subsystem that includes two or more wavelength-variable filters. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an input focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an output focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes a linear variable filter, and the filtering parameters of the linear variable filter vary based on the spatial position on the linear variable filter, and the linear variable filter is disposed at the rear focal plane of the input focusing optical component and the front focal plane of the output focusing optical component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an input angle scanning component disposed at the front focal plane of the input focusing optical component to receive the input beam, the input focusing optical component receives the input beam from the input angle scanning component, directs the input beam to the linear variable filter, and the position of the input beam on the linear variable filter is selectable based on the angle of the input angle scanning component. In another exemplary embodiment, one of the two or more wavelength-variable filters includes an output angle scanning component disposed at the rear focal plane of the output focusing optical component, and the output focusing optical component receives the input beam as a filtered beam from the linear variable filter and directs the filtered beam to the output angle scanning component. In another exemplary embodiment, the input angle scanning component of the first wavelength-variable filter among the two or more wavelength-variable filters is the input angle scanning component of the filtering subsystem and receives irradiation as an input beam from the irradiation source. In another exemplary embodiment, the output beam of all but the last of the two or more wavelength-variable filters is the input beam of the next wavelength-variable filter among the two or more wavelength-variable filters. In another exemplary embodiment, the output angle scanning component of the last wavelength-variable filter among the two or more wavelength-variable filters is the output angle scanning component of the filtering subsystem.

[0009] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the claimed invention. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the general description, serve to explain the principles of the invention.

[0010] Those skilled in the art can better understand the numerous advantages of this disclosure by referring to the accompanying drawings.

Brief Description of the Drawings

[0011]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4A

Figure 4B

DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, reference is made in detail to the disclosed subject matter as shown in the accompanying drawings. The present disclosure is illustrated and described in particular with respect to several embodiments and specific features thereof. The embodiments described herein are to be understood as illustrative and not restrictive. It should be immediately apparent to those skilled in the art that various changes and modifications in form and detail can be made without departing from the spirit and scope of the present disclosure.

[0013] Embodiments of the present disclosure are directed to systems and methods for the rapid and flexible tuning of various characteristics of a broadband irradiation source using a linear variable filter and scanning optics. The linear variable filter can include a filter having filtering characteristics that vary along a linear filtering direction. For example, a linear variable neutral filter can achieve various amounts of broadband luminance reduction based on the spatial position of the input beam along a straight axis. As another example, a linear variable low-pass (or wideband) filter can achieve low-pass filtering with a cutoff wavelength that varies based on the spatial position of the input beam along the linear filtering direction. As another example, the linear variable filter can be formed as a polarizer, and the direction of polarization that the linear variable filter passes through can vary in different directions along the linear filtering direction. It is contemplated herein that the systems and methods disclosed herein can utilize a linear variable filter that modifies any selected characteristic of the input beam.

[0014] In one embodiment, a wavelength tunable filter includes a pair of focusing mirrors in a 4-f configuration (e.g., an input focusing mirror and an output focusing mirror), a linear variable filter in the pupil plane (e.g., the rear focal plane of the input focusing mirror and the front focal plane of the output focusing mirror), and an angular scanning component in the other focal plane of the focusing mirrors. For example, a parallel input beam is incident on an input tilting mirror, which directs it at a selected angle toward the input focusing mirror, focuses it on the linear variable filter at a selected position based on the selected angle, collimates it again by the output focusing mirror, and can be directed along any selected output angle by the output tilting mirror. In this configuration, the position of the input beam on the linear variable filter, and thus the effect of the linear variable filter on the input beam, can be selected by controlling the angle of the input angle scanning component. Further, the output focusing mirror will direct the filtered input beam (e.g., the filtered beam) toward the output angle scanning component regardless of the selected angle of the input angle scanning component. Thus, the angles of both the input and output angle scanning components can be selected to direct the filtered beam along any selected path.

[0015] Additional embodiments of the present disclosure are directed to stacking multiple wavelength tunable filters to achieve synchronization of multiple parameters of an input beam. In this way, multiple wavelength tunable filters, each having a different linear variable filter, can be arranged in series to filter the input beam in sequence. For example, a stack of wavelength tunable filters can include one or more wavelength tunable filters having a linear variable neutral filter for output (or luminance) control and one or more wavelength tunable filters having a linear variable spectral filter for spectrum control. In one embodiment, the output angle scanning component of the first wavelength tunable filter can operate as the input angle scanning component of the second wavelength tunable filter. In another embodiment, each wavelength tunable filter can have separate input and output wavelength tunable filters.

[0016] Additional embodiments of the present disclosure are directed to simultaneous filtering and channel selection. It is contemplated herein that the wavelength tunable filters disclosed herein may be capable of realizing the selection of an input source or an output source in addition to filtering. For example, two or more input sources may be positioned to supply two or more input beams to the input angle scanning component of the wavelength tunable filter. In this configuration, the input and / or output angle scanning component may be configured to direct the input beam so that it exits as a filtered beam along the selected output beam path through a selected position on the linear variable filter within the wavelength tunable filter from the selected input source. As another example, the output angle scanning component may direct the filtered beam along any of two or more output beam paths.

[0017] Additional embodiments of the present disclosure are directed to speckle reduction using filtered beams from a wavelength tunable filter. In one embodiment, the output angle scanning component may be controlled to scan the filtered beam around a selected angular range to reduce the speckle associated with the coherent filtered beam. For example, the output angle scanning component may scan the filtered beam along the input surface of the fiber to reduce or eliminate the speckle associated with the illumination of a sample using the filtered beam from the output surface of the fiber.

[0018] Next, with reference to FIGS. 1A-4B, systems and methods for wavelength tunable filtering are disclosed in more detail in accordance with one or more embodiments of the present disclosure.

[0019] FIG. 1A is a schematic diagram of a wavelength tunable filtering system 100 according to one or more embodiments of the present disclosure.

[0020] In one embodiment, the wavelength-variable filtering system 100 includes at least one wavelength-variable filter 102. The wavelength-variable filter 102 may include a pair of focusing optical components 104 (for example, an input focusing optical component 104a and an output focusing optical component 104b), a linear variable filter 106 disposed within a pupil plane (for example, the rear focal plane of the input focusing optical component 104a and the front focal plane of the output focusing optical component 104b), and an angular scanning component 108 disposed on another focal plane of the focusing optical component 104. For example, the input angular scanning component 108a may be disposed on the front focal plane of the input focusing optical component 104a, and the output angular scanning component 108b may be disposed on the rear focal plane of the output focusing optical component 104b.

[0021] The wavelength-variable filter 102 may accept any input beam 110 having any spectral wavelength or wavelength range. For example, the input beam 110 may include wavelengths within the extreme ultraviolet, ultraviolet, visible, and / or infrared spectral regions, without limitation. Further, the input beam 110 may be generated by any suitable illumination source (or combination of illumination sources) including, without limitation, a narrowband laser source, a supercontinuum laser source, a light-emitting diode (LED), a laser-driven plasma source, or a lamp source. Further, the input beam 110 may include light from a plurality of illumination sources propagating along a common input path. For example, the input beam 110 may include light from a supercontinuum laser source and light from one or more additional illumination sources for supplementing the spectrum of the supercontinuum laser. In one embodiment, the input beam 110 includes light from a supercontinuum laser source and a laser diode having a spectrum including 405 nm for supplementing the spectrum of the supercontinuum laser.

[0022] The linear variable filter 106 can include any type of filter in which the amplitude or effect of the filtering varies along the linear filtering direction. In this regard, the effect of the linear variable filter 106 on the input beam 110 can vary (e.g., be tunable) based on the spatial position of the input beam 110 on the linear variable filter 106. In one embodiment, the linear variable filter 106 includes a neutral filter. For example, the linear variable filter 106 can achieve various amounts of broadband luminance reduction based on the spatial position of the input beam 110 along the linear filtering direction. In another embodiment, the linear variable filter 106 includes a spectral filter. For example, a linear variable filter 106 configured as an edge filter (e.g., a low-pass filter or a high-pass filter) can achieve a varying cutoff wavelength based on the spatial position of the input beam 110 on the linear variable filter 106. As another example, at least one of the width or the center wavelength of a band-pass filter or a band-stop filter can vary based on the spatial position of the input beam 110 on the linear variable filter 106. As another example, the linear variable filter 106 can be formed as a polarizer, and the direction of polarization that the linear variable filter passes (e.g., transmits) can be different in different directions along the linear filtering direction. As another example, the linear variable filter 106 can include one or more waveplates, and the thickness varies along the linear filtering direction.

[0023] Furthermore, the filtering characteristics of the linear variable filter 106 can vary in an arbitrary manner along the linear filtering direction. In one embodiment, the filtering characteristics vary continuously along the filtering direction such that the characteristics of the input beam 110 can be finely tuned by a small adjustment of the spatial position of the input beam 110 on the linear variable filter 106. For example, a linear variable filter 106 that realizes spectral luminance control may be well suited to realizing continuously varying filtering characteristics, although not limited thereto. However, the linear filtering direction need not be monotonic or continuous. In another embodiment, the linear variable filter 106 includes one or more distinct sections having distinct characteristics. In this configuration, the input beam 110 can be directed to any distinct position to realize distinct filtering. For example, the linear variable filter 106 may include distinct sections that realize distinct polarization passing directions, waveplate configurations, and the like.

[0024] Furthermore, it can be generally understood that the linear variable filter 106 can realize variations of a plurality of characteristics (e.g., luminance and spectrum) as a function of the position along the linear filtering direction so as to realize any desired filtering characteristics as a function of the position along the linear filtering direction.

[0025] The focusing optical component 104 can include any type of optical element well known in the art and can be selected based on the expected spectrum of the input beam 110. In one embodiment, at least one of the focusing optical components 104 includes a reflective optical element. In this regard, the focusing optical component 104 may be suitable for broadband and / or UV applications. For example, the focusing optical component 104 may include, although not limited thereto, a parabolic mirror or an elliptical mirror. In another embodiment, at least one of the focusing optical components 104 includes a reflective optical element. For example, the focusing optical component 104 may include, although not limited thereto, a refractive scanning lens.

[0026] The focusing optical component 104 can have an arbitrarily selected focal length. Further, the focusing optical component 104 can have the same focal length, although not necessarily. In the case of the focusing optical component 104, the wavelength-variable filter 102 can expand or contract the diameter of the input beam 110 based on the ratio of the focal lengths.

[0027] The angular scanning component 108 can include any type of adjustable mirror that implements an adjustable tip and / or tilt, including but not limited to a galvanometer mirror, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system (MEMS) deflector.

[0028] Referring now to FIG. 1B, selective tuning using the linear variable filter 106 is shown in accordance with one or more embodiments of the present disclosure. FIG. 1B is a schematic diagram of a portion of the wavelength-variable filter 102 that includes an input angular scanning component 108a, a linear variable filter 106, and an input focusing optical component 104a, in accordance with one or more embodiments of the present disclosure.

[0029] In one embodiment, the input angle scanning component 108a is disposed on the front focal plane of the input focusing optical component 104a, and the linear variable filter 106 is disposed on the rear focal plane of the input focusing optical component 104a. In this configuration, the dispersion of light at the input angle scanning component 108a and the linear variable filter 106 is related by Fourier transform, and the spatial position of the light on the linear variable filter 106 is based on the angle 112 of the light from the input angle scanning component 108a. Accordingly, the characteristics of the filtered beam 114 (e.g., the input beam 110 filtered by the linear variable filter 106) can be tuned by controlling the angle 112 of the input focusing optical component 104a. Thus, for example, the parallel input beam 110 incident on the input angle scanning component 108a is focused onto the linear variable filter 106 by the input focusing optical component 104a at a position controlled by the angle 112 of the input angle scanning component 108a. As another example, a Gaussian beam positioned with a beam waist on the input angle scanning component 108a can be relayed to have another beam waist on the linear variable filter 106.

[0030] FIG. 1C is a schematic diagram of the wavelength variable filter 102 showing the path of the parallel input beam 110 according to one or more embodiments of the present disclosure. For purposes of illustration, the path of the input beam 110 in FIG. 1C is represented as a single ray of light. Specifically, FIG. 1C shows five selectable paths of the input beam 110 from the input path 116, generated by five different angles 112 of the input angle scanning component 108a, that interact with the linear variable filter 106 at five different locations along the linear filtering direction to achieve different characteristics of the filtered beam 114. Further, FIG. 1C shows how the filtered beam 114 can be directed as the output beam 120 along a common output path 118 from the output angle scanning component 108b, regardless of the selected angle 112 of the input angle scanning component 108a.

[0031] In one embodiment, the wavelength tunable filter 102 includes an output focusing optical component 104b and an output angle scanning component 108b. The linear variable filter 106 is disposed on the front focal plane of the output focusing optical component 104b, and the output angle scanning component 108b is disposed on the rear focal plane of the output focusing optical component 104b. In this regard, the output focusing optical component 104b can collect the filtered beam 114 emerging from any location of the linear variable filter 106 and supply the filtered beam 114 as an output beam 120 along a common output axis (e.g., along a common output direction). Further, this configuration of the wavelength tunable filter 102 can correspond to a 4-f system such that the input beam 110 and the filtered beam 114 can both have the same divergence characteristics. For example, the parallel input beam 110 will emerge from the wavelength tunable filter 102 as a parallel filtered beam 114.

[0032] In another embodiment, as shown in FIG. 1C, the wavelength tunable filter 102 can include a cross-axis angle scanning component 108c. Further, the wavelength tunable filter 102 can include one or more relay lenses 122 for relaying the output beam 120 from the output angle scanning component 108b to the cross-axis angle scanning component 108c. For example, the cross-axis angle scanning component 108c can provide deflection along an orthogonal angle that is greater than that provided by the output angle scanning component 108b. In this regard, the output path 118 can generally exist along any direction in three dimensions, thereby facilitating the precise placement of the output beam 120. For example, the combination of the output angle scanning component 108b and the cross-axis angle scanning component 108c can achieve the precise placement of the output beam 120 on the output fiber.

[0033] Next, with reference to FIGS. 2A - 2C, the selection of the position of the input beam 110 on the linear variable filter 106 through the control of the angle scanning component 108 will be described in more detail in accordance with one or more embodiments of the present disclosure.

[0034] FIG. 2A is a schematic diagram of a wavelength-variable filter 102 showing the path of an input beam 110 interacting with a linear variable filter 106 at a central position 202 according to one or more embodiments of the present disclosure. In FIG. 2A, the position δ of the input beam 110 on the linear variable filter 106 x is measured with respect to the central position 202 and has a maximum absolute value D corresponding to the length from the central position 202 to the end of the usable portion of the linear variable filter 106. The angle θ corresponds to the angle between the incidence and reflection of the input beam 110 by the input focusing optical component 104a corresponding to this central position 202. The angle φ1 of the input angle scanning component 108a is measured with respect to the nominal angle corresponding to this central position 202.

[0035] In one embodiment, the position δ of the input beam 110 on the linear variable filter 106 x can be characterized as follows,

Equation

[0036] FIG. 2B is a plot showing the position (δ x ) of the input beam 110 on the linear variable filter 106 along the linear filtering direction as a function of the angle φ1 of the input angle scanning component 108a according to one or more embodiments of the present disclosure. Specifically, the plot of FIG. 2B corresponds to the configuration of the wavelength-variable filter 102 where f = 160 mm and D = 60 mm. As shown in FIG. 2B, the position δ of the input beam 110 on the linear variable filter 106 x can vary linearly as a function of the angle φ1 of the input angle scanning component 108a.

[0037] FIG. 2C is a plot showing the angle φ2 of the output angle scanning component 108b as a function of the angle φ1 of the input angle scanning component 108a of FIG. 2B required to supply the filtered beam 114 as the output beam 120 along a common (e.g., fixed) output path 118 for any selected angle φ1 of the input angle scanning component 108a according to one or more embodiments of the present disclosure.

[0038] In one embodiment, for any selected angle φ1 of the input angle scanning component 108a, the angle φ2 of the output angle scanning component 108b as a function of the angle φ1 of the input angle scanning component 108a of FIG. 2B required to supply the filtered beam 114 as the output beam 120 along the common output path 118 is characterized as follows:

Equation

[0039] Next, referring to FIG. 3, a combination of a plurality of wavelength-variable filters 102 is described in more detail in accordance with one or more embodiments of the present disclosure. It is contemplated herein that the plurality of wavelength-variable filters 102 can be combined in series to achieve adjusted filtering of a plurality of characteristics of an input beam. In this configuration, the plurality of wavelength-variable filters 102 can form a filtering subsystem 302, the input beam 110 for the first of the wavelength-variable filters 102 can be the input beam to the filtering subsystem 302, the output beam 120 of all but the last of the wavelength-variable filters 102 can be the input beam 110 for the subsequent wavelength-variable filter 102, and the output beam 120 of the last of the wavelength-variable filters 102 can be the output beam 120 of the filtering subsystem 302.

[0040] Furthermore, the various wavelength-variable filters 102 within the filtering subsystem 302 can share any components, although not necessarily, and without limitation, focusing optics 104 or angular scanning components 108.

[0041] FIG. 3 is a schematic diagram of a plurality of wavelength-variable filters 102 having different linear variable filters 106 for filtering a plurality of characteristics of an input beam 110, according to one or more embodiments of the present disclosure. Specifically, FIG. 3 shows a first wavelength-variable filter 102-1 including an input angular scanning component 108a-1 and an output angular scanning component 108b-1 in series, a second wavelength-variable filter 102-2 including an input angular scanning component 108a-2 and an output angular scanning component 108b-2, and a third wavelength-variable filter 102-3 including an input angular scanning component 108a-3 and an output angular scanning component 108b-3. For example, the linear variable filters 106 of the three wavelength-variable filters 102 can include, without limitation, a neutral filter, a low-pass spectral filter, and a high-pass spectral filter in any order.

[0042] It is contemplated herein that the tunable filter 102 can be combined in various ways to filter multiple characteristics of the input beam 110. In one embodiment, as shown in FIG. 3, the output angle scanning component 108b-1 of the first tunable filter 102-1 is also the input angle scanning component 108a-2 of the second tunable filter 102-2. Similarly, the output angle scanning component 108b-2 of the second tunable filter 102-2 is also the input angle scanning component 108a-3 of the third tunable filter 102-3. In this regard, any number of tunable filters 102 can be provided in series to filter the input beam 110. In another embodiment, although not shown, each tunable filter 102 can include separate input angle scanning component 108a and output angle scanning component 108b.

[0043] In one embodiment, as shown in FIG. 3, consecutive tunable filters 102 (e.g., tunable filters 102-1, 102-2, 102-3 in FIG. 3) may share the focusing optics 104, although not necessarily. For example, as shown in FIG. 3, the output focusing optics 104b-1 and the input focusing optics 104a-2 are formed as a common optical element. Similarly, the output focusing optics 104b-2 and the input focusing optics 104a-3 are formed as a common optical element. However, the input focusing optics 104a-1 and the output focusing optics 104b-3 are formed as separate elements. In another embodiment, although not shown, each tunable filter 102 can include separate focusing optics 104.

[0044] FIG. 3 further shows a cross-axis angle scanning component 108c and a relay lens 122 for implementing control regarding the output path 118 from the filtering subsystem 302. Specifically, FIG. 3 shows two possible output paths 118.

[0045] Referring again to FIG. 1A, the wavelength-variable filtering system 100 may include a controller 124, which may be communicatively coupled to any component of the wavelength-variable filtering system 100, such as, but not limited to, an angle scanning component 108 (e.g., an input angle scanning component 108a, an output angle scanning component 108b, and / or a cross-axis angle scanning component 108c).

[0046] In another embodiment, the controller 124 includes one or more processors 126 configured to execute program instructions maintained in a memory device 128 or in memory. The one or more processors 126 of the controller 124 may include any processing element well known in the art. In this sense, the one or more processors 126 may include any microprocessor-type device configured to execute algorithms and / or instructions. Further, the memory device 128 may include any storage medium well known in the art suitable for storing program instructions executable by the associated one or more processors 126. For example, the memory device 128 may include a non-transitory memory medium. As an additional example, the memory device 128 may include, but is not limited to, a read-only memory (ROM), a random access memory (RAM), a magnetic or optical memory device (e.g., a disk), a magnetic tape, a solid state drive, and the like. It should be further noted that the memory device 128 may be housed within a common controller housing with the one or more processors 126.

[0047] In this regard, the one or more processors 126 of the controller 124 may execute any of the various process steps described throughout the present disclosure. For example, the one or more processors 126 of the controller 124 may control the angle of the angle scanning component 108 (e.g., the input angle scanning component 108a, the output angle scanning component 108b, and / or the cross-axis angle scanning component 108c) to effect wavelength-variable filtering of the input beam 110.

[0048] In one embodiment, the user interface 130 is communicatively coupled to the controller 124. In one embodiment, the user interface 130 may include, but is not limited to, one or more desktops, laptops, tablets, etc. In another embodiment, the user interface 130 includes a display used to display data of the wavelength-variable filtering system 100 to the user. The display of the user interface 130 may include any display well-known in the art. For example, the display may include, but is not limited to, a liquid crystal display (LCD), an organic light emitting diode (OLED)-based display, or a CRT display. Those skilled in the art should understand that any display device that can be integrated with the user interface 130 is suitable for implementation in the present disclosure. In another embodiment, the user may input selections and / or commands in response to the data displayed to the user via the user input device of the user interface 130.

[0049] Next, with reference to FIGS. 4A and 4B, an illumination system 402 including at least one wavelength-variable filter 102 will be described in more detail in accordance with one or more embodiments of the present disclosure. Specifically, the illumination system 402 of FIGS. 4A and 4B includes three wavelength-variable filters 102 (e.g., a first wavelength-variable filter 102-1, a second wavelength-variable filter 102-2, and a third wavelength-variable filter 102-3) shown in FIG. 3. However, it should be understood that this particular configuration is provided for illustrative purposes only, and the illumination system 402 may include any number of wavelength-variable filters 102 of any configuration.

[0050] FIG. 4A is a schematic diagram of an illumination system 402 including two illumination sources 404 that supply an input beam 110 along a common input path 116, according to one or more embodiments of the present disclosure.

[0051] In one embodiment, the irradiation system 402 includes one or more irradiation sources 404 within one or more irradiation channels 406. For example, in FIG. 4A, light from two irradiation sources 404 is combined as a common input beam 110 along a common input path 116 (e.g., using a beam combiner 408). In one embodiment, the first irradiation source 404 includes a supercontinuum laser source, and the second irradiation source 404 includes a laser diode (e.g., having a wavelength of about 405 nm).

[0052] In another embodiment, the irradiation system 402 includes one or more output channels 410. Specifically, FIG. 4A shows two output channels 410 each coupled to an output fiber 412 through a coupling lens 414. In this regard, the output beam 120 from one or more wavelength-variable filters 102 can be selectively directed into any of the output channels 410. For example, different output channels 410 can be used to provide irradiation with different characteristics. As an example, a controller 124 can selectively direct light having different filtered characteristics (e.g., generated by different selected positions of the input beam 110 on one or more linear variable filters 106 within one or more wavelength-variable filters 102) into different output channels 410. As another example, different output channels 410 can be configured to effect irradiation (e.g., of a sample) at different incident angles, polarizations, etc.

[0053] FIG. 4A further shows the cross-axis angle scanning component 108c and relay lens 122 described with respect to FIG. 1C. In this regard, the combination of the output angle scanning component 108b-3 and the cross-axis angle scanning component 108c can achieve three-dimensional control with respect to the output path 118 of the output beam 120.

[0054] Next, with reference to FIG. 4B, the use of a wavelength-variable filter 102 (or a series of wavelength-variable filters 102) to effect selection of the irradiation channel 406 and / or output channel 410 is described in more detail in accordance with one or more embodiments of the present disclosure.

[0055] FIG. 4B is a schematic diagram of an illumination system 402 that includes an illumination source 404 that supplies an input beam 110 along different input paths 116, according to one or more embodiments of the present disclosure.

[0056] In one embodiment, any combination of the angular scanning components 108 can be adjusted to select a particular illumination source 404. For example, the angle of the input angular scanning component 108a (e.g., input angular scanning component 108a-1 of FIG. 4B) can be adjusted to direct light from any selected illumination source 404 to a selected position on the tunable filter 106, and tunable filtering of the input beam 110 from the selected illumination source 404 can be achieved. As another example, the output angular scanning component 108b (e.g., output angular scanning component 108b-3 of FIG. 4B) and / or the cross-axis angular scanning component 108c can be adjusted to select the illumination source 404 by directing light from the selected illumination source 404 along a desired output path 118. In this regard, it is contemplated herein that the tunable filter 102 is symmetric and that any combination of the input angular scanning component 108a and the output angular scanning component 108b can select the illumination source 404. Further, it should be understood that any of the angular scanning components 108 can be adjusted to effect selection of the illumination source 404.

[0057] In another embodiment, any combination of the angular scanning components 108 can be adjusted to supply an output beam 120 to a selected output channel 410 from any illumination source 404. Although the selection of the illumination source 404 is the same as described above, it is contemplated herein that the output channel 410 can be selected using the reverse concept. For example, any combination of the input angular scanning component 108a (e.g., input angular scanning component 108a-1 of FIG. 4B) and the output angular scanning component 108b (e.g., output angular scanning component 108b-3 of FIG. 4B) can be adjusted to supply the output beam 120 from any selected illumination source 404 to any selected output channel 410.

[0058] In another embodiment, a wavelength-variable filter 102 (or a series of wavelength-variable filters 102) can be used to reduce speckle. For example, when irradiating a sample with coherent light (e.g., the coherent output beam 120 from the wavelength-variable filter 102 disclosed herein) for surface profiling of the sample, speckle can be present. In one embodiment, the output angle scanning component 108b and / or the cross-axis angle scanning component 108c of the wavelength-variable filter 102 are controlled to modulate the output angle of the output beam 120 along the output path 118, and the speckle can be reduced. For example, the output angle scanning component 108b and / or the cross-axis angle scanning component 108c can rapidly vibrate the output beam 120 along an arbitrary pattern (e.g., a randomized pattern, a scanned pattern, etc.) within a selected range of the output angle, introducing a small fluctuation in the output path 118. If the time scale of the vibration is shorter than the measurement time scale (e.g., the exposure time), the effect of the speckle can be averaged by the vibration of the output beam 120. Further, reducing speckle through the vibration of the output angle scanning component 108b and / or the cross-axis angle scanning component 108c is contemplated herein to enable faster vibrations than typical speckle reduction techniques such as rotating a diffuser plate or mechanically vibrating an illumination fiber. Thus, the wavelength-variable filter 102 described herein can enable a shorter measurement time scale (e.g., exposure time) than typical speckle reduction techniques, which can also enable improving the measurement throughput without sacrificing performance.

[0059] In one embodiment, the output angle scanning component 108b and / or the cross-axis angle scanning component 108c of the wavelength tunable filter 102 can rapidly vibrate the output beam 120 on the input surface of the optical fiber. In this way, modulating the emission conditions of the spatially coherent output beam 120 at the entrance of the optical fiber (e.g., multimode optical fiber) can modulate the near-field and far-field speckle distributions of the light emerging from the fiber. Provided that the vibration is within the numerical aperture (NA) of the fiber's collection aperture, the entire output of the output beam 120 can be captured. For example, in FIG. 4B, the output angle scanning component 108b-3 and / or the cross-axis angle scanning component 108c can be configured to vibrate the output beam 120 on the input surface of any of the output fibers 412 (e.g., using the controller 124).

[0060] The subject matter described herein may show different components that are included within or connected to other components. It should be understood that such illustrated architectures are merely exemplary and that many other architectures that actually achieve the same functionality may be implemented. In a conceptual sense, any combination of components for achieving the same functionality is substantially "associated" so that the desired functionality is achieved. Thus, any two components of this specification combined to achieve a particular function can be understood to be "associated" with each other such that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated can also be considered to be "connected" or "coupled" to each other to achieve the desired function, and any two components that can be so associated can also be considered to be "couplable" to each other to achieve the desired function. Specific examples of couplable include, but are not limited to, components that can physically interact and / or are physically interacting, and / or components that can wirelessly interact and / or are wirelessly interacting, and / or components that can logically interact and / or are logically interacting.

[0061] It is believed that many of the present disclosure and its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes in the shape, construction, and combination of the components can be made without departing from the disclosed subject matter or sacrificing all of its material advantages. The forms described are illustrative only and such changes are intended to be embraced and included by the following claims. Further, it is to be understood that the invention is defined by the appended claims.

Claims

1. an input focusing optical component, an output focusing optical component, a linear variable filter, wherein the filtering parameter of the linear variable filter varies based on a spatial position on the linear variable filter, and the linear variable filter is disposed at a rear focal plane of the input focusing optical component and a front focal plane of the output focusing optical component; an input angle scanning component disposed at a front focal plane of the input focusing optical component configured to receive an input beam, wherein the input focusing optical component receives the input beam from the input angle scanning component, directs the input beam to the linear variable filter, and a position of the input beam on the linear variable filter is selectable based on an angle of the input angle scanning component; an output angle scanning component disposed at a rear focal plane of the output focusing optical component, wherein the output focusing optical component receives the input beam as a filtered beam from the linear variable filter, directs the filtered beam to the output angle scanning component, and the output angle scanning component supplies the filtered beam as an output beam along an output path selectable based on an angle of the output angle scanning component; comprising a cross-axis angle scanning component for receiving the output beam from the output angle scanning component, wherein a scanning plane of the cross-axis angle scanning component is orthogonal to a scanning plane of the output angle scanning component, and the output beam can be directed along an arbitrary output angle by controlling the output angle scanning component and the cross-axis angle scanning component; a wavelength variable filter further comprising the cross-axis angle scanning component.

2. The wavelength variable filter according to claim 1, a controller communicably coupled to the input angle scanning component and the output angle scanning component, the controller including one or more processors configured to execute program instructions to cause the one or more processors to select the angle of the input angle scanning component to select the position of the input beam on the linear variable filter a controller including the one or more processors. The wavelength variable filter further comprising the controller.

3. The wavelength variable filter according to claim 2, wherein the one or more processors cause the one or more processors to Select the angle of the output angle scanning component based on the angle of the input angle scanning component so as to direct the output beam along a fixed output path A wavelength tunable filter further configured to execute program instructions to cause. **Claim 4** The wavelength tunable filter according to claim 2, wherein the one or more processors cause the one or more processors to Select at least one of the output angle scanning component or the input angle scanning component to direct the output beam to a selected output channel among two or more output channels A wavelength tunable filter further configured to execute program instructions to cause. **Claim 5** The wavelength tunable filter according to claim 2, wherein the one or more processors cause the one or more processors to Select at least one of the output angle scanning component or the input angle scanning component to receive the input beam from a selected irradiation source among two or more irradiation sources A wavelength tunable filter further configured to execute program instructions to cause. **Claim 6** The wavelength tunable filter according to claim 1, A controller communicatively coupled to the input angle scanning component and the output angle scanning component, the one or more processors causing the one or more processors to Modulate the output angle scanning component and the cross-axis angle scanning component to modulate the output angle and reduce speckle A controller including the one or more processors configured to execute program instructions to cause A wavelength tunable filter further comprising. **Claim 7** The wavelength tunable filter according to claim 6, A coupling lens for directing the output beam from the cross-axis angle scanning component to an input surface of an optical fiber, wherein modulating the output angle scanning component and the cross-axis angle scanning component to modulate the output angle modulates at least one of the position or angle of the output beam on the input surface of the optical fiber, the coupling lens A wavelength tunable filter further comprising. **Claim 8** The wavelength tunable filter according to claim 1, wherein at least one of the input focusing optics or the output focusing optics Comprises at least one of a parabolic mirror, an elliptical mirror, or a refractive scanning lens A wavelength tunable filter comprising. **Claim 9** The wavelength tunable filter according to claim 1, wherein the linear variable filter Wavelength-variable filter including a linear variable spectral filter A wavelength-variable filter including a linear variable spectral filter

10. The wavelength-variable filter according to claim 9, wherein the linear variable spectral filter is At least one of a long-pass filter or a short-pass filter, and the cut-off wavelength varies based on the position on the linear variable spectral filter, at least one of a long-pass filter or a short-pass filter A wavelength-variable filter including a linear variable spectral filter

11. The wavelength-variable filter according to claim 9, wherein the linear variable spectral filter is A band-pass filter, and at least one of the center pass wavelength or the spectral pass width varies based on the position on the linear variable spectral filter, a band-pass filter A wavelength-variable filter including a linear variable spectral filter

12. The wavelength-variable filter according to claim 1, wherein the linear variable filter is A linear variable neutral filter, and the transmittance varies based on the position on the linear variable neutral filter, a linear variable neutral filter A wavelength-variable filter including a linear variable spectral filter

13. The wavelength-variable filter according to claim 1, wherein the linear variable filter is A linear variable polarizer, and the transmitted polarization varies based on the position on the linear variable polarizer, a linear variable polarizer A wavelength-variable filter including a linear variable spectral filter

14. The wavelength-variable filter according to claim 1, wherein at least one of the input angle scanning component or the output angle scanning component is At least one of a galvanometer, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system (MEMS) deflector A wavelength-variable filter including a linear variable spectral filter

15. Two or more wavelength-variable filters, wherein one of the two or more wavelength-variable filters is An input focusing optical component, An output focusing optical component, A linear variable filter, wherein the filtering parameter of the linear variable filter is different based on the spatial position on the linear variable filter, and the linear variable filter is disposed at the rear focal plane of the input focusing optical component and the front focal plane of the output focusing optical component, a linear variable filter An input angle scanning component disposed on the front focal plane of the input focusing optical component configured to receive an input beam, wherein the input angle scanning component receives the input beam from the input focusing optical component, directs the input beam to the linear variable filter, and the position of the input beam on the linear variable filter is selectable based on the angle of the input angle scanning component. An output angle scanning component disposed on the rear focal plane of the output focusing optical component, wherein the output focusing optical component receives the input beam as a filtered beam from the linear variable filter, directs the filtered beam to the output angle scanning component, and the output beams of all but the last of the two or more wavelength variable filters are the input beams of the next wavelength variable filter among the two or more wavelength variable filters. A cross-axis angle scanning component for receiving the output beam from the output angle scanning component, wherein the scanning plane of the cross-axis angle scanning component is orthogonal to the scanning plane of the output angle scanning component, and the output beam can be directed along an arbitrary output angle by controlling the output angle scanning component and the cross-axis angle scanning component. Comprising two or more wavelength variable filters A system comprising **Claim 16** An irradiation system, comprising An irradiation source configured to generate an input beam, A filtering subsystem including two or more wavelength variable filters, wherein one of the two or more wavelength variable filters is An input focusing optical component, An output focusing optical component, A linear variable filter, wherein the filtering parameters of the linear variable filter are different based on the spatial position on the linear variable filter, and the linear variable filter is disposed on the rear focal plane of the input focusing optical component and the front focal plane of the output focusing optical component. An input angle scanning component disposed on the front focal plane of the input focusing optical component configured to receive the input beam, wherein the input focusing optical component receives the input beam from the input angle scanning component, directs the input beam to the linear variable filter, and the position of the input beam on the linear variable filter is selectable based on the angle of the input angle scanning component. An output angle scanning component disposed on the rear focal plane of the output focusing optical component, wherein the output focusing optical component receives the input beam as a filtered beam from the linear variable filter and directs the filtered beam to the output angle scanning component. A filtering subsystem comprising: Comprising: A cross-axis angle scanning component for receiving the output beam of the filtering subsystem from the output angle scanning component of the filtering subsystem, wherein the scanning plane of the cross-axis angle scanning component is orthogonal to the scanning plane of the output angle scanning component of the filtering subsystem, and the output beam can be directed along an arbitrary output angle by controlling the output angle scanning component and the cross-axis angle scanning component of the filtering subsystem. Further comprising: An irradiation system, wherein the input angle scanning component of the first wavelength variable filter among the two or more wavelength variable filters is the input angle scanning component of the filtering subsystem, receives irradiation as the input beam from the irradiation source, the output beam of all wavelength variable filters other than the last one among the two or more wavelength variable filters is the input beam of the next wavelength variable filter among the two or more wavelength variable filters, and the output angle scanning component of the last wavelength variable filter among the two or more wavelength variable filters is the output angle scanning component of the filtering subsystem. Claim 17 The irradiation system according to claim 16, A controller communicatively coupled to the two or more wavelength variable filters, and to one or more processors, selects the angle of the input angle scanning component of the filtering subsystem to select the position of the input beam on the linear variable filter A controller including the one or more processors configured to execute program instructions to cause An irradiation system further comprising.

18. The irradiation system according to claim 17, wherein the one or more processors cause the one or more processors to Select an angle of the output angle scanning component of the filtering subsystem based on the angle of the input angle scanning component so as to direct the output beam along a fixed output path An irradiation system further configured to execute program instructions to cause.

19. The irradiation system according to claim 17, wherein the one or more processors cause the one or more processors to Select at least one of the angle of the output angle scanning component of the filtering subsystem or the angle of the input angle scanning component of the filtering subsystem so as to direct the output beam to a selected output channel among two or more output channels An irradiation system further configured to execute program instructions to cause.

20. The irradiation system according to claim 17, wherein the irradiation source is the first irradiation source among two or more irradiation sources, and the one or more processors cause the one or more processors to Select at least one of the angle of the output angle scanning component of the filtering subsystem or the angle of the input angle scanning component of the filtering subsystem so as to receive light from a selected irradiation source among two or more irradiation sources as the input beam to the filtering subsystem An irradiation system further configured to execute program instructions to cause.

21. The irradiation system according to claim 17, wherein A controller communicatively coupled to the input angle scanning component and the output angle scanning component, the one or more processors causing the one or more processors to Modulate the output angle scanning component and the cross-axis angle scanning component of the filtering subsystem to modulate the output angle and reduce speckle A controller including the one or more processors configured to execute program instructions to cause An irradiation system further comprising.

22. The irradiation system according to claim 21, wherein A coupling lens for directing the output beam from the cross-axis angle scanning component to the input surface of the optical fiber, wherein modulating the output angle scanning component and the cross-axis angle scanning component of the filtering subsystem to modulate the output angle modulates at least one of the position or angle of the output beam of the filtering subsystem on the input surface of the optical fiber. An irradiation system further comprising the same.

23. The irradiation system according to claim 16, wherein at least one of the input focusing optical component or the output focusing optical component of any one of the two or more wavelength variable filters comprises at least one of a parabolic mirror, an elliptical mirror, or a refractive scanning lens An irradiation system.

24. The irradiation system according to claim 16, wherein the linear variable filter of any one of the two or more wavelength variable filters comprises at least one of a linear variable spectral filter, a linear variable neutral filter, a linear variable polarizer, or a linear variable wave plate An irradiation system.

25. The irradiation system according to claim 16, wherein at least one of the input angle scanning component or the output angle scanning component of any one of the two or more wavelength variable filters comprises at least one of a galvanometer, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system (MEMS) deflector An irradiation system.

26. The irradiation system according to claim 16, wherein the irradiation source comprises at least one of a supercontinuum laser source, a laser-driven plasma source, or a laser diode An irradiation system.

27. The irradiation system according to claim 16, wherein the two or more wavelength variable filters comprise a first wavelength variable filter, wherein the linear variable filter of the first wavelength variable filter comprises a neutral filter, a first wavelength variable filter, and a second wavelength variable filter, wherein the linear variable filter of the second wavelength variable filter comprises a low-pass spectral filter, a second wavelength variable filter, and a third wavelength variable filter, wherein the linear variable filter of the third wavelength variable filter comprises a high-pass spectral filter, a third wavelength variable filter An irradiation system.

28. The irradiation system according to claim 27, wherein the irradiation source is supercontinuum laser source The irradiation system including.

29. The irradiation system according to claim 28, wherein at least one of the input focusing optical component or the output focusing optical component of any one of the two or more wavelength variable filters is parabolic mirror The irradiation system provided with.

30. The irradiation system according to claim 29, wherein at least one of the input angle scanning component or the output angle scanning component of any one of the two or more wavelength variable filters is galvanometer The irradiation system provided with.

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