Broadband illumination tuning

Abstract

A tunable optical filter can include an input focusing optic, an output focusing optic, a linearly varying optical filter positioned at a back focal plane of the input focusing optic and a front focal plane of the output focusing optic, an input angular scanning component configured to receive an input beam positioned at a front focal plane of the input focusing optic, and an output angular scanning component positioned at a back focal plane of the output focusing optic. The input focusing optic can receive the input beam from the input angular scanning component and direct the input beam to the linearly varying optical filter, where a position of the input beam on the linearly varying optical filter can be selected based on an angle of the input angular scanning component. The output focusing optic can receive a filtered beam from the linearly varying optical filter and direct the filtered beam to the output angular scanning component.

Description

[0001] Cross-reference of related applications

[0002] This application claims the right to U.S. Provisional Application No. 62 / 971,982, entitled “Broadband Laser Tuning,” filed February 9, 2020, pursuant to 35 U.S. SC §119(e), the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to tuning broadband lighting sources and, more specifically, to rapidly tuning coherent broadband lighting sources using scanning optics and linearly varying filters. Background Technology

[0004] Tunable light sources can provide illumination tuned to one or more selected wavelengths within a given spectral range. However, typical tunable light sources suffer from limited ability to rapidly and precisely modify the intensity or spectrum of the tuned illumination beam. Furthermore, typical external tunable filters suffer from slow tuning speeds, limited spectral bandwidth, or limited polarization requirements. Therefore, it is desirable to provide a system and method for addressing, for example, the aforementioned drawbacks. Summary of the Invention

[0005] A tunable filter according to one or more illustrative embodiments of the present disclosure is disclosed. In one illustrative embodiment, the tunable filter includes an input focusing optics. In another illustrative embodiment, the tunable filter includes an output focusing optics. In another illustrative embodiment, the tunable filter includes a linearly varying filter, wherein the filtering parameters of the linearly varying filter differ based on its spatial position on the linearly varying filter. In another illustrative embodiment, the linearly varying filter is positioned at the rear focal plane of the input focusing optics and the front focal plane of the output focusing optics. In another illustrative embodiment, the tunable filter includes an input angle scanning assembly positioned at the front focal plane of the input focusing optics to receive an input beam, wherein the input focusing optics receives the input beam from the input angle scanning assembly and guides the input beam to the linearly varying filter. In another illustrative embodiment, the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning assembly. In another illustrative embodiment, the tunable filter includes an output angle scanning assembly positioned at the back focal plane of an output focusing optics, wherein the output focusing optics receives an input beam from a linearly varying filter as a filtered beam and guides the filtered beam to the output angle scanning assembly. In another illustrative embodiment, the output angle scanning assembly provides the filtered beam as an output beam along an output path selectable based on the angle of the output angle scanning assembly.

[0006] A system according to one or more illustrative embodiments of the present disclosure is disclosed. In one illustrative embodiment, the system includes two or more tunable filters. In another illustrative embodiment, one of the two or more tunable filters includes an input focusing optics. In another illustrative embodiment, one of the two or more tunable filters includes an output focusing optics. In another illustrative embodiment, one of the two or more tunable filters includes a linearly varying filter, wherein the filtering parameters of the linearly varying filter differ based on its spatial position on the linearly varying filter, and wherein the linearly varying filter is positioned at the rear focal plane of the input focusing optics and the front focal plane of the output focusing optics. In another illustrative embodiment, one of the two or more tunable filters includes an input angle scanning component positioned at the front focal plane of the input focusing optics to receive an input beam, wherein the input angle scanning component receives the input beam from the input focusing optics and guides the input beam to the linearly varying filter. In another illustrative embodiment, the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning component. In another illustrative embodiment, one of the two or more tunable filters includes an output angle scanning component positioned at the back focal plane of an output focusing optics, wherein the output focusing optics receives the input beam from the linearly varying filter as a filtered beam and guides the filtered beam to the output angle scanning component. In another illustrative embodiment, the output beam, excluding the last tunable filter among the two or more tunable filters, is the input beam for the subsequent tunable filters among the two or more tunable filters.

[0007] An illumination system according to one or more illustrative embodiments of the present disclosure is disclosed. In one illustrative embodiment, the illumination system includes an illumination source for generating an input light beam. In another illustrative embodiment, the illumination system includes a filter subsystem comprising two or more tunable filters. In another illustrative embodiment, one of the two or more tunable filters includes an input focusing optics. In another illustrative embodiment, one of the two or more tunable filters includes an output focusing optics. In yet another illustrative embodiment, one of the two or more tunable filters includes a linearly varying filter, wherein the filtering parameters of the linearly varying filter differ based on its spatial position on the linearly varying filter, and wherein the linearly varying filter is positioned at the rear focal plane of the input focusing optics and the front focal plane of the output focusing optics. In another illustrative embodiment, one of the two or more tunable filters includes an input angle scanning component positioned at the front focal plane of an input focusing optics to receive an input beam, wherein the input focusing optics receives the input beam from the input angle scanning component and guides the input beam to a linearly varying filter, and wherein the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning component. In another illustrative embodiment, one of the two or more tunable filters includes an output angle scanning component positioned at the rear focal plane of an output focusing optics, wherein the output focusing optics receives the input beam from the linearly varying filter as a filtered beam and guides the filtered beam to the output angle scanning component. In another illustrative embodiment, the input angle scanning component of the first tunable filter among the two or more tunable filters is the input angle scanning component of the filtering subsystem and receives illumination from an illumination source as an input beam. In another illustrative embodiment, the output beam, excluding the last tunable filter among two or more tunable filters, is the input beam for the subsequent tunable filters among the two or more tunable filters. In another illustrative embodiment, the output angle scanning component of the last tunable filter among the two or more tunable filters is the output angle scanning component of the filtering subsystem.

[0008] It should be understood that the above overview and the following detailed description are merely exemplary and illustrative, and do not necessarily limit the invention as claimed. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the overview, serve to explain the principles of the invention. Attached Figure Description

[0009] By referring to the accompanying drawings, those skilled in the art can better understand the many advantages of this disclosure, among which:

[0010] Figure 1A This is a schematic diagram of a tunable filter system according to one or more embodiments of the present disclosure.

[0011] Figure 1B This is a schematic diagram of a portion of a tunable filter including an input angle scanning component, a linearly varying filter, and an input focusing optics, according to one or more embodiments of the present disclosure.

[0012] Figure 1C This is a schematic diagram illustrating the path of a collimated input beam according to one or more embodiments of the present disclosure.

[0013] Figure 2A This is a schematic diagram illustrating the path of an input beam that interacts with a linearly varying filter at a central position according to one or more embodiments of the present disclosure.

[0014] Figure 2B This describes a linearly varying filter (δ) along a linear filtering direction, which varies according to the angle φ1 of the input angle scanning component based on one or more embodiments of the present disclosure. x A plot of the position of the input beam on the graph.

[0015] Figure 2C This describes the provision of a filtered beam as an output beam along a common output path for any selected angle φ1 of the input angle scanning component, according to one or more embodiments of the present disclosure. Figure 2B The plot of the output angle scanning component is a change of the angle φ2 of the input angle scanning component, which is the angle φ1 of the input angle scanning component.

[0016] Figure 3 This is a schematic diagram of a plurality of tunable filters having different linearly varying properties for filtering an input beam, according to one or more embodiments of the present disclosure.

[0017] Figure 4A This is a schematic diagram of an illumination system comprising two illumination sources providing an input beam along a common input path, according to one or more embodiments of the present disclosure.

[0018] Figure 4B This is a schematic diagram of an illumination system comprising illumination sources that provide input beams along different input paths, according to one or more embodiments of the present disclosure. Detailed Implementation

[0019] Reference will now be made in detail to the disclosed subject matter illustrated in the accompanying drawings. This disclosure has been particularly shown and described with respect to certain embodiments and their specific features. The embodiments set forth herein are to be considered illustrative rather than restrictive. It will be readily apparent to those skilled in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of this disclosure.

[0020] Embodiments of this disclosure relate to systems and methods for rapidly and flexibly tuning various properties of a broadband illumination source using linearly varying filters and scanning optics. A linearly varying filter may comprise a filter having a filtering rotation property that varies along a linear filtering direction. For example, a linearly varying neutral density filter may provide a varying amount of broadband intensity reduction based on the spatial position of the input beam along a linear axis. By another example, a linearly varying low-pass (or high-pass) filter may provide low-pass filtering with a cutoff wavelength that varies based on the spatial position of the input beam along a linear filtering direction. By yet another example, a linearly varying filter may be configured as a polarizer, wherein the polarization direction passing through the linearly varying filter may differ in different directions along the linear filtering direction. The systems and methods disclosed herein are contemplated that can utilize linearly varying filters that modify any selected properties of the input beam.

[0021] In one embodiment, the tunable filter includes a pair of focusing lenses (e.g., an input focusing lens and an output focusing lens) configured in a 4-f arrangement, a linearly varying filter in the pupil plane (e.g., the back focal plane of the input focusing lens and the front focal plane of the output focusing lens), and angle scanning components at other focal planes of the focusing lenses. For example, a collimated input beam can be incident on an input tilting lens, guided by the input tilting lens at a selected angle to the input focusing lens, focused on a linearly varying filter located at a selected position based on the selected angle, collimated again by the output focusing lens, and guided by the output tilting lens along any selected output angle. In this configuration, the position of the input beam on the linearly varying filter and thus the effect of the linearly varying filter on the input beam can be selected by controlling the angle of the input angle scanning component. Furthermore, the output focusing lens guides the filtered input beam (e.g., the filtered beam) to the output angle scanning component regardless of the selected angle of the input angle scanning component. Therefore, the angles of the input and output angle scanning components can be jointly selected to guide the filtered beam along any selected path.

[0022] Additional embodiments of this disclosure relate to stacking multiple tunable filters to provide tuning of multiple parameters of an input beam. In this manner, multiple tunable filters, each having a different linear variation filter, can be arranged in series to sequentially filter the input beam. For example, a stack of tunable filters may include one or more tunable filters having a linear variation neutral density filter for power (or intensity) control and one or more tunable filters having a linear variation spectral filter for spectral control. In one embodiment, the output angle scanning component of a first tunable filter is operable as the input angle scanning component of a second tunable filter. In another embodiment, each tunable filter may have separate input and output tunable filters.

[0023] Additional embodiments of this disclosure pertain to simultaneous filtering and channel selection. Tunable filters as disclosed herein are contemplated to provide selection of input or output sources in addition to filtering. For example, two or more input sources may be positioned to provide two or more input beams to an input angle scanning assembly of the tunable filter. In this configuration, the input and / or output angle scanning assembly may be configured to guide an input beam from a selected input source through a selected position on a linearly varying filter within the tunable filter, and exit as a filtered beam along a selected output beam path. By another example, the output angle scanning assembly may guide the filtered beam along any of two or more output beam paths.

[0024] Additional embodiments of this disclosure pertain to reducing spotting when using a filter beam from a tunable filter. In one embodiment, an output angle scanning component can be controlled to scan the filter beam around a selected angle range to mitigate spotting associated with a coherent filter beam. For example, the output angle scanning component can scan the filter beam along the input surface of an optical fiber to reduce or eliminate spotting associated with illuminating a sample using a filter beam from the output surface of the optical fiber.

[0025] For reference Figures 1A to 4B The present disclosure provides more detailed information on systems and methods for tunable filtering according to one or more embodiments of the present disclosure.

[0026] Figure 1A This is a schematic diagram of a tunable filter system 100 according to one or more embodiments of the present disclosure.

[0027] In one embodiment, the tunable filtering system 100 includes at least one tunable filter 102. The tunable filter 102 may include a pair of focusing optics 104 (e.g., an input focusing optics 104a and an output focusing optics 104b), a linearly varying filter 106 positioned at a pupil plane (e.g., the rear focal plane of the input focusing optics 104a and the front focal plane of the output focusing optics 104b), and an angle scanning assembly 108 positioned at other focal planes of the focusing optics 104. For example, the input angle scanning assembly 108a may be positioned at the front focal plane of the input focusing optics 104a, and the output angle scanning assembly 108b may be positioned at the rear focal plane of the output focusing optics 104b.

[0028] The tunable filter 102 can accept any input beam 110 having any spectral wavelength or wavelength range. For example, the input beam 110 may include (but is not limited to) wavelengths in the extreme ultraviolet, ultraviolet, visible, and / or infrared spectral regions. Furthermore, the input beam 110 can be generated by any suitable illumination source (or combination of sources) including (but not limited to) a narrowband laser source, a supercontinuum laser source, a light-emitting diode (LED), a laser-driven plasma source, or a lamp source. Additionally, the input beam 110 may include light from multiple illumination sources propagating along a common input path. For example, the input beam 110 may include light from a supercontinuum laser source and one or more additional illumination sources to supplement 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 to supplement the spectrum of the supercontinuum laser.

[0029] The linear variation filter 106 may comprise any type of filter, the amplitude or effect of which varies along the linear filtering direction. In this respect, the effect of the linear variation filter 106 on the input beam 110 may vary (e.g., may be tuned) based on the spatial position of the input beam 110 on the linear variation filter 106. In one embodiment, the linear variation filter 106 comprises a neutral density filter. For example, the linear variation filter 106 may provide a varying amount of broadband intensity reduction based on the spatial position of the input beam 110 along the linear filtering direction. In another embodiment, the linear variation filter 106 comprises a spectral filter. For example, the linear variation filter 106 configured as an edge filter (e.g., a low-pass filter or a high-pass filter) may provide a varying cutoff wavelength based on the spatial position of the input beam 110 on the linear variation filter 106. By another example, at least one of the width or center wavelength of the bandpass or bandstop filter can vary based on the spatial position of the input beam 110 on the linearly varying filter 106. By another example, the linearly varying filter 106 can be formed as a polarizer, wherein the polarized light passing through (e.g., transmitted) through the linearly varying filter can be different in different directions along the linear filtering direction. By another example, the linearly varying filter 106 can include one or more waveplates, wherein the thickness varies along the linear filtering direction.

[0030] Furthermore, the optical rotation properties of the linearly varying filter 106 can be varied in any manner along the linear filtering direction. In one embodiment, the optical rotation properties vary continuously along the filtering direction, allowing the properties of the input beam 110 to be finely tuned by small adjustments to the spatial position of the input beam 110 on the linearly varying filter 106. For example, the linearly varying filter 106, which provides spectrally controlled intensity, is well-suited, but not limited to, providing continuously varying optical rotation properties. However, the linear filtering direction need not be monotonic or continuous. In another embodiment, the linearly varying filter 106 comprises one or more discrete segments with discrete properties. In this configuration, the input beam 110 can be directed to any discrete position to provide discrete filtering. For example, the linearly varying filter 106 may comprise discrete segments providing discrete polarization transmission directions, waveplate configurations, or the like.

[0031] Furthermore, the linear variation filter 106 can provide variations in multiple properties (e.g., intensity and spectrum) that vary depending on the position along the linear filtering direction, such that the linear variation filter 106 can generally be understood as providing any desired optical rotation property that varies depending on the position along the linear filtering direction.

[0032] The focusing optics 104 may comprise any type of optical element known in the art and may be selected based on the desired spectrum of the input beam 110. In one embodiment, at least one of the focusing optics 104 comprises a reflective optical element. In this respect, the focusing optics 104 may be suitable for broadband and / or UV applications. For example, the focusing optics 104 may comprise (but is not limited to) a parabolic mirror or an elliptical mirror. In another embodiment, at least one of the focusing optics 104 comprises a reflective optical element. For example, the focusing optics 104 may comprise (but is not limited to) a refractive scanning lens.

[0033] The focusing optics 104 may have any selected focal length. Furthermore, the focusing optics 104 may have, but need not have, the same focal length. In the case of the focusing optics 104, the tunable filter 102 may expand or shrink the diameter of the input beam 110 based on the ratio of the focal lengths.

[0034] The angle scanning assembly 108 may include any type of adjustable mirror that provides an adjustable tip and / or tilt, including (but not limited to) a flow detector, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system (MEMS) deflector.

[0035] For reference Figure 1B This illustrates the selective tuning of the linear variation filter 106 according to one or more embodiments of the present disclosure. Figure 1B This is a schematic diagram of a portion of a tunable filter 102 comprising an input angle scanning component 108a, a linear variation filter 106, and an input focusing optics 104a, according to one or more embodiments of the present disclosure.

[0036] In one embodiment, the input angle scanning component 108a is positioned at the front focal plane of the input focusing optics 104a, and the linear variation filter 106 is positioned at the rear focal plane of the input focusing optics 104a. In this configuration, the light distribution at the input angle scanning component 108a and the linear variation filter 106 is correlated by a Fourier transform, and the spatial position of the light on the linear variation filter 106 is based on the angle 112 of the light from the input angle scanning component 108a. Therefore, the properties of the filtered beam 114 (e.g., the input beam 110 filtered by the linear variation filter 106) can be tuned by controlling the angle 112 of the input focusing optics 104a. For example, the collimated input beam 110 incident on the input angle scanning component 108a will thus be focused onto the linear variation filter 106 by the input focusing optics 104a located at a position controlled by the angle 112 of the input angle scanning component 108a. By another example, a Gaussian beam positioned at the waist of the input angle scanning assembly 108a can be relayed to have another waist on the linearly varying filter 106.

[0037] Figure 1C This is a schematic diagram illustrating the path of a collimated input beam 110 according to one or more embodiments of the present disclosure, using a tunable filter 102. For illustrative purposes, Figure 1C The path of the input beam 110 is represented as a single ray. Specifically, Figure 1C This describes five selectable paths for the input beam 110, generated by five different angles 112 of the input angle scanning component 108a, to interact with the linearly varying filter 106 at five different positions along the linear filtering direction to provide different properties for the filtered beam 114. Furthermore, Figure 1C This describes how the filter beam 114 can be guided from the output angle scanning component 108b as the output beam 120 along the common output path 118 regardless of the selected angle 112 of the input angle scanning component 108a.

[0038] In one embodiment, the tunable filter 102 includes an output focusing optics 104b and an output angle scanning assembly 108b, wherein a linearly varying filter 106 is positioned at the front focal plane of the output focusing optics 104b and the output angle scanning assembly 108b is positioned at the rear focal plane of the output focusing optics 104b. In this respect, the output focusing optics 104b can collect the filtered beam 114 emitted from any position of the linearly varying filter 106 and provide the filtered beam 114 as an output beam 120 along a common output axis (e.g., along a common output direction). Furthermore, this configuration of the tunable filter 102 corresponds to a 4-f system such that both the input beam 110 and the filtered beam 114 can have the same divergence properties. For example, the collimated input beam 110 will be emitted from the tunable filter 102 as the collimated filtered beam 114.

[0039] In another embodiment, such as Figure 1C The description indicates that the tunable filter 102 may include a transverse angle scanning assembly 108c. Furthermore, the tunable filter 102 may include one or more relay lenses 122 to relay the output beam 120 from the output angle scanning assembly 108b to the transverse angle scanning assembly 108c. For example, the transverse angle scanning assembly 108c may provide deflection along an orthogonal angle compared to the deflection provided by the output angle scanning assembly 108b. In this respect, the output path 118 can typically be located in any direction in three dimensions, which facilitates precise positioning of the output beam 120. For example, a combination of the output angle scanning assembly 108b and the transverse angle scanning assembly 108c can provide precise positioning of the output beam 120 on the output fiber.

[0040] For reference Figures 2A to 2CThe following describes in more detail how, according to one or more embodiments of the present disclosure, the position of the input beam 110 on the linearly varying filter 106 is selected by controlling the angle scanning component 108.

[0041] Figure 2A This is a schematic diagram illustrating the path of an input beam 110 interacting with a linearly varying filter 106 at a central position 202, according to one or more embodiments of the present disclosure. Figure 2A In the middle, the position δ of the input beam 110 on the linearly varying filter 106 is measured relative to the center position 202. x It also has a maximum absolute value D corresponding to the length of the usable portion from the center position 202 to the edge of the linearly varying filter 106. The angle θ corresponds to the angle between the incident and reflected light beam 110 by the input focusing optics 104a corresponding to this center position 202. The angle φ1 of the input angle scanning assembly 108a is measured relative to the nominal angle corresponding to this center position 202.

[0042] In one embodiment, the position δ of the input beam 110 on the linearly varying filter 106 is... x It can be characterized as follows:

[0043]

[0044] Where f is the focal length of the input angle scanning component 108a.

[0045] Figure 2B This describes a linearly varying filter 106 (δ) along a linear filtering direction, which varies according to the angle φ1 of the input angle scanning component 108a based on one or more embodiments of the present disclosure. x A plot of the position of the input beam 110 on the graph. Specifically, Figure 2B The plot in the diagram corresponds to the configuration of the tunable filter 102, where f = 160 mm and D = 60 mm. For example... Figure 2B The description states that the position δ of the input beam 110 on the linearly varying filter 106 is... x It can change linearly according to the angle φ1 of the input angle scanning component 108a.

[0046] Figure 2C This illustrates that, according to one or more embodiments of the present disclosure, a filter beam 114 is provided along a common (e.g., fixed) output path 118 for any selected angle φ1 of the input angle scanning assembly 108a as required for the output beam 120. Figure 2B The plot of the angle φ2 of the output angle scanning component 108b varies with the angle φ1 of the input angle scanning component 108a.

[0047] In one embodiment, a filter beam 114 is provided along the common output path 118 according to any selected angle φ1 for the input angle scanning component 108a as the required source for the output beam 120. Figure 2B The angle φ2 of the output angle scanning component 108b, which varies with the angle φ1 of the input angle scanning component 108a, can be characterized as follows:

[0048]

[0049] Where relative to the corresponding Figure 2A The center position 202 (e.g., δ) x The nominal angle measurement outputs the angle φ2 of the angle scanning component 108b, where the focal length of the output angle scanning component 108b is also equal to f. Furthermore, the angle φ2 is generated based on the configuration of a tunable filter 102, wherein the focal length of the output angle scanning component 108b is also equal to f. Figure 2C The plot in the image. For example... Figure 2C The description states that the angle φ2 of the output angle scanning component 108b required to provide the output beam 120 along the common output path 118 can vary linearly based on the selection of the angle φ1 of the input angle scanning component 108a.

[0050] For reference Figure 3 The present disclosure describes in more detail combinations of multiple tunable filters 102 according to one or more embodiments. Contemplate herein that multiple tunable filters 102 may be combined in series to provide customized filtering of multiple properties of an input beam. In this configuration, the multiple tunable filters 102 may form a filtering subsystem 302, wherein the input beam 110 of a first tunable filter 102 may be the input beam of the filtering subsystem 302, the output beam 120 of all but the last tunable filter 102 is the input beam 110 of subsequent tunable filters 102, and the output beam 120 of the last tunable filter 102 is the output beam 120 of the filtering subsystem 302.

[0051] Furthermore, the various tunable filters 102 in the filter subsystem 302 may share, but need not share, any components that include (but are not limited to) the focusing optics 104 or the angle scanning assembly 108.

[0052] Figure 3 This is a schematic diagram of a plurality of tunable filters 102 having different linearly varying properties for filtering an input beam 110, according to one or more embodiments of the present disclosure. Specifically, Figure 3The description describes a series of three tunable filters: a first tunable filter 102-1 comprising an input angle scanning component 108a-1 and an output angle scanning component 108b-1; a second tunable filter 102-2 comprising an input angle scanning component 108a-2 and an output angle scanning component 108b-2; and a third tunable filter 102-3 comprising an input angle scanning component 108a-3 and an output angle scanning component 108b-3. For example, the linearly varying filter 106 of the three tunable filters 102 can include (but is not limited to) a neutral density filter, a low-pass spectral filter, and a high-pass spectral filter in any order.

[0053] This document considers that the tunable filter 102 can be combined in various ways to filter multiple properties of the input beam 110. In one embodiment, such as Figure 3 As explained, 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 respect, 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 may include a separate input angle scanning component 108a and an output angle scanning component 108b.

[0054] In one embodiment, such as Figure 3 The description states that the continuously tunable filter 102 (e.g., Figure 3 The tunable filters 102-1, 102-2, and 102-3 can share, but do not need to share, the focusing optics 104. For example, such as Figure 3 As described, 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 may include a separate focusing optics 104.

[0055] Figure 3 Further explanation is provided regarding the horizontal axis angle scanning assembly 108c and the relay lens 122, which provide control over the output path 118 from the filter subsystem 302. Specifically, Figure 3 This indicates two possible output paths, 118.

[0056] Refer again Figure 1AThe tunable filter system 100 may include a controller 124, which may be communicatively coupled to any component of the tunable filter system 100, such as (but not limited to) the angle scanning component 108 (e.g., the input angle scanning component 108a, the output angle scanning component 108b, and / or the horizontal axis angle scanning component 108c).

[0057] In another embodiment, controller 124 includes one or more processors 126 configured to execute program instructions held on memory device 128 or memory. The one or more processors 126 of controller 124 may include any processing element 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. Furthermore, memory device 128 may include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 126. For example, memory device 128 may include non-transitory memory media. As additional examples, memory device 128 may include (but is not limited to) read-only memory (ROM), random access memory (RAM), magnetic or optical memory devices (e.g., magnetic disks), magnetic tape, solid-state drives, and the like. It should further be noted that memory device 128 may be housed with one or more processors 126 within a common controller housing.

[0058] In this regard, one or more processors 126 of controller 124 may perform any of the various process steps described throughout this disclosure. For example, one or more processors 126 of controller 124 may control the angle of angle scanning assembly 108 (e.g., input angle scanning assembly 108a, output angle scanning assembly 108b, and / or transverse angle scanning assembly 108c) to provide tunable filtering of input beam 110.

[0059] In one embodiment, user interface 130 is communicatively coupled to controller 124. In one embodiment, user interface 130 may include (but is not limited to) one or more desktop computers, laptop computers, tablet computers, and the like. In another embodiment, user interface 130 includes a display for displaying data of the tunable filter system 100 to a user. The display of user interface 130 may include any display 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 will recognize that any display device capable of being integrated with user interface 130 is suitable for implementation in this disclosure. In another embodiment, a user may input selections and / or commands in response to data displayed to the user via user input devices of user interface 130.

[0060] For reference Figure 4A and 4B The following describes in more detail an illumination system 402 comprising at least one tunable filter 102 according to one or more embodiments of the present disclosure. Specifically, Figure 4A and 4B The lighting system 402 in the middle includes Figure 3 The three tunable filters 102 described herein (e.g., first tunable filter 102-1, second tunable filter 102-2, and third tunable filter 102-3) are shown. However, it should be understood that this particular configuration is provided for illustrative purposes only and the lighting system 402 may contain any number of tunable filters 102 in any configuration.

[0061] Figure 4A This is a schematic diagram of an illumination system 402 comprising two illumination sources 404 providing an input beam 110 along a common input path 116, according to one or more embodiments of the present disclosure.

[0062] In one embodiment, the lighting system 402 includes one or more lighting sources 404 in one or more lighting channels 406. For example, in Figure 4A In this configuration, light from two illumination sources 404 is combined along a common input path 116 (e.g., using a beam combiner 408) to form a common input beam 110. In one embodiment, the first illumination source 404 comprises a supercontinuum laser source and the second illumination source 404 comprises a laser diode (e.g., having a wavelength of approximately 405 nm).

[0063] In another embodiment, the lighting system 402 includes one or more output channels 410. Specifically, Figure 4A Two output channels 410 are described, each coupled to an output fiber 412 via a coupling lens 414. In this respect, an output beam 120 from one or more tunable filters 102 can be selectively directed into any of the output channels 410. For example, different output channels 410 can be used to provide illumination with different characteristics. In one example, a controller 124 can selectively direct light with different optical rotation properties (e.g., generated by the input beam 110 at different selected positions on one or more linearly varying filters 106 of one or more tunable filters 102) to different output channels 410. In another example, different output channels 410 can be configured to provide (e.g., sample) illumination at different incident angles, polarization, or similar settings.

[0064] Figure 4A Further explanation as to... Figure 1CThe description includes the transverse angle scanning assembly 108c and the relay lens 122. In this respect, the combination of the output angle scanning assembly 108b-3 and the transverse angle scanning assembly 108c can provide three-dimensional control over the output path 118 of the output beam 120.

[0065] For reference Figure 4B The present disclosure describes in more detail the use of a tunable filter 102 (or a series of tunable filters 102) to provide selection of illumination channel 406 and / or output channel 410 according to one or more embodiments of the present disclosure.

[0066] Figure 4B This is a schematic diagram of an illumination system 402 comprising an illumination source 404 providing an input beam 110 along different input paths 116, according to one or more embodiments of the present disclosure.

[0067] In one embodiment, any combination of adjustable angle scanning components 108 can be used to select a specific lighting source 404. For example, adjustable input angle scanning component 108a (e.g., Figure 4B The angle of the input angle scanning component 108a-1 is adjusted to guide light from any selected illumination source 404 to a selected position on the linearly varying filter 106 to provide tunable filtering of the input beam 110 from the selected illumination source 404. By another example, the output angle scanning component 108b (e.g., ...) can be adjusted. Figure 4B The output angle scanning components 108b-3 and / or the horizontal axis angle scanning component 108c are used to select the illumination source 404 by guiding light from the selected illumination source 404 along the desired output path 118. In this regard, it is considered herein that the tunable filter 102 is symmetrical and any combination of the input angle scanning components 108a and the output angle scanning components 108b can select the illumination source 404. Furthermore, it should be understood that any of the angle scanning components 108 can be adjusted to provide selection of the illumination source 404.

[0068] In another embodiment, any combination of adjustable angle scanning components 108 can be used to provide the output beam 120 from any illumination source 404 to a selected output channel 410. It is contemplated herein that the same concept as described above for selecting illumination source 404 can be used to select output channel 410, but in reverse. For example, adjustable input angle scanning components 108a (e.g., Figure 4B The input angle scanning component 108a-1 and the output angle scanning component 108b (e.g., Figure 4B Any combination of the output angle scanning components 108b-3 in ...

[0069] In another embodiment, a tunable filter 102 (or a series of tunable filters 102) can be used to mitigate spotting. For example, spotting may be present when the sample is illuminated with coherent light (e.g., a coherent output beam 120 from a tunable filter 102 as disclosed herein), due to the surface roughness of the sample. In one embodiment, the output angle scanning assembly 108b and / or the transverse angle scanning assembly 108c of the tunable filter 102 can be controlled to modulate the output angle of the output beam 120 along the output path 118 to mitigate spotting. For example, the output angle scanning assembly 108b and / or the transverse angle scanning assembly 108c can rapidly oscillate the output beam 120 along any pattern (e.g., randomization, scanning, or the like) within a selected output angle range to introduce smaller fluctuations in the output path 118. If the oscillation timescale is shorter than the measurement timescale (e.g., exposure time), the effect of spotting can be averaged out by the oscillation of the output beam 120. Furthermore, this paper considers that oscillation reduction of the spot by the output angle scanning component 108b and / or the transverse axis angle scanning component 108c can facilitate faster oscillations than typical spot reduction techniques (e.g., rotating diffusers or mechanically vibrating illumination fibers). Therefore, the tunable filter 102 as described herein can achieve a shorter measurement timescale (e.g., exposure time) than typical spot reduction techniques, which in turn improves measurement processing capabilities without sacrificing performance.

[0070] In one embodiment, the output angle scanning assembly 108b and / or the transverse axis angle scanning assembly 108c of the tunable filter 102 can rapidly oscillate the output beam 120 at the input surface of the optical fiber. In this way, the emission conditions of the spatially coherent output beam 120 at the entrance of the modulated optical fiber (e.g., multimode fiber) can modulate the near-field and far-field spot distribution of the light emitted from the fiber. If the oscillation occurs within the collecting numerical aperture (NA) of the optical fiber, then the full power of the output beam 120 can be captured. For example, in... Figure 4B In this configuration, the output angle scanning components 108b-3 and / or the horizontal axis angle scanning components 108c can be configured (e.g., using a controller 124) to oscillate the output beam 120 on the input surface of either of the output optical fibers 412.

[0071] The objects described herein sometimes refer to different components contained within or connected to other components. It should be understood that such depicted architectures are merely exemplary, and many other architectures can in fact be implemented to achieve the same functionality. Conceptually, any arrangement of components used to achieve the same functionality is effectively “associated” to achieve the desired functionality. Therefore, any two components combined herein to achieve a particular functionality can be considered “associated” with each other to achieve the desired functionality, regardless of the architecture or intermediate components. Similarly, any two such associated components can also be considered “connected” or “coupled” to each other to achieve the desired functionality, and any two components that can be suchly associated can also be considered “coupleable” to each other to achieve the desired functionality. Specific examples of coupleability include, but are not limited to, components that can physically interact and / or physically interact with each other, and / or components that can wirelessly interact and / or wirelessly interact with each other, and / or components that can logically interact and / or logically interact with each other.

[0072] It is believed that this disclosure and its many accompanying advantages will be understood from the foregoing description, and it will be apparent that various changes can be made to the form, construction, and arrangement of the components without departing from the subject matter of the disclosure or sacrificing all its significant advantages. The forms described are merely illustrative, and the appended claims are intended to cover and encompass such changes. Furthermore, it should be understood that the invention is defined by the appended claims.

Claims

1. A tunable filter, comprising: Input focusing optics; Output focusing optics; A linearly variable filter, wherein the filtering parameters of the linearly variable filter vary based on the spatial position on the linearly variable filter, wherein the linearly variable filter is positioned at the back focal plane of the input focusing optics and the front focal plane of the output focusing optics; An input angle scanning assembly is formed as a first reflector with an adjustable angle and positioned at the front focal plane of the input focusing optics, wherein the input focusing optics receives an input beam from the input angle scanning assembly and guides the input beam to the linearly varying filter, wherein the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning assembly; and An output angle scanning assembly is formed as a second reflector with an adjustable angle and positioned at the back focal plane of the output focusing optics, wherein the output focusing optics receives the input beam from the linearly varying filter as a filter beam and guides the filter beam to the output angle scanning assembly, wherein the output angle scanning assembly provides the filter beam as an output beam along an output path selectable based on the angle of the output angle scanning assembly.

2. The tunable filter according to claim 1, further comprising: A controller communicatively coupled to the input angle scanning component and the output angle scanning component, the controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: The angle of the input angle scanning component is selected to select the position of the input beam on the linearly varying filter.

3. The tunable filter of claim 2, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: The angle of the output angle scanning component is selected based on the angle of the input angle scanning component to guide the output beam along a fixed output path.

4. The tunable filter of claim 2, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: Select the angle of at least one of the output angle scanning component or the input angle scanning component to guide the output beam to a selected output channel among two or more output channels.

5. The tunable filter of claim 2, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: Select the angle of at least one of the output angle scanning component or the input angle scanning component to receive the input beam from a selected lighting source among two or more lighting sources.

6. The tunable filter according to claim 1, further comprising: A transverse angle scanning component for receiving the output beam from the output angle scanning component, wherein the scanning plane of the transverse angle scanning component is orthogonal to the scanning plane of the output angle scanning component, wherein the output beam can be guided along any output angle by controlling the output angle scanning component and the transverse angle scanning component.

7. The tunable filter according to claim 6, further comprising: A controller communicatively coupled to the input angle scanning component and the output angle scanning component, the controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: The output angle scanning component and the horizontal axis angle scanning component are modulated to modulate the output angle to reduce speckle.

8. The tunable filter according to claim 7, further comprising: A coupling lens is used to guide the output beam from the transverse angle scanning assembly to the input surface of the optical fiber, wherein the output angle scanning assembly and the transverse angle scanning assembly are modulated to modulate the output angle to modulate at least one of the position or angle of the output beam on the input surface of the optical fiber.

9. The 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.

10. The tunable filter according to claim 1, wherein the linearly varying filter comprises: Linear variation spectral filter.

11. The tunable filter according to claim 10, wherein the linearly varying spectral filter comprises: At least one of a long-pass filter or a short-pass filter, wherein the cutoff wavelength varies based on the position on the linearly varying spectral filter.

12. The tunable filter according to claim 10, wherein the linearly varying spectral filter comprises: A bandpass filter, wherein at least one of the center pass wavelength or spectral pass width varies based on the position on the linearly varying spectral filter.

13. The tunable filter according to claim 1, wherein the linearly varying filter comprises: A linearly varying neutral density filter, wherein the transmittance varies based on the position on the linearly varying neutral density filter.

14. The tunable filter according to claim 1, wherein the linearly varying filter comprises: A linearly variable polarizer, wherein the polarized light varies based on the position on the linearly variable polarizer.

15. The tunable filter of claim 1, wherein at least one of the input angle scanning component or the output angle scanning component comprises: At least one of a galvanometer, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system deflector.

16. A system comprising: Two or more tunable filters, wherein the tunable filters among the two or more tunable filters include: Input focusing optics; Output focusing optics; A linearly variable filter, wherein the filtering parameters of the linearly variable filter vary based on the spatial position on the linearly variable filter, wherein the linearly variable filter is positioned at the rear focal plane of the input focusing optics and the front focal plane of the output focusing optics; An input angle scanning assembly is formed as a first reflector with an adjustable angle and positioned at the front focal plane of the input focusing optics, wherein the input angle scanning assembly receives an input beam from the input focusing optics and guides the input beam to the linearly varying filter, wherein the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning assembly; and An output angle scanning assembly is formed as a second reflector with an adjustable angle and positioned at the back focal plane of the output focusing optics, wherein the output focusing optics receives the input beam from the linearly varying filter as a filter beam and guides the filter beam to the output angle scanning assembly, wherein the output beam other than the last tunable filter among the two or more tunable filters is the input beam of the subsequent tunable filter among the two or more tunable filters.

17. A lighting system comprising: A lighting source configured to produce an input beam of light; and A filtering subsystem comprising two or more tunable filters, wherein the tunable filters among the two or more tunable filters include: Input focusing optics; Output focusing optics; A linearly variable filter, wherein the filtering parameters of the linearly variable filter vary based on the spatial position on the linearly variable filter, wherein the linearly variable filter is positioned at the rear focal plane of the input focusing optics and the front focal plane of the output focusing optics; An input angle scanning assembly is formed as a first reflector with an adjustable angle and positioned at the front focal plane of the input focusing optics, wherein the input focusing optics receives the input beam from the input angle scanning assembly and guides the input beam to the linearly varying filter, wherein the position of the input beam on the linearly varying filter can be selected based on the angle of the input angle scanning assembly; and An output angle scanning assembly is formed as a second reflector with an adjustable angle and positioned at the back focal plane of the output focusing optics, wherein the output focusing optics receives the input beam from the linearly varying filter as a filter beam and guides the filter beam to the output angle scanning assembly; and The input angle scanning component of the first tunable filter among the two or more tunable filters is the input angle scanning component of the filtering subsystem and receives illumination from the illumination source as the input beam, wherein the output beam other than the last tunable filter among the two or more tunable filters is the input beam of the subsequent tunable filters among the two or more tunable filters, and the output angle scanning component of the last tunable filter among the two or more tunable filters is the output angle scanning component of the filtering subsystem.

18. The lighting system of claim 17, further comprising: A controller, communicatively coupled to the two or more tunable filters, the controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: The angle of the input angle scanning component of the filter subsystem is selected to select the position of the input beam on the linearly varying filter.

19. The lighting system of claim 18, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: The angle of the output angle scanning component of the filter subsystem is selected based on the angle of the input angle scanning component to guide the output beam along a fixed output path.

20. The lighting system of claim 18, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: Select the angle of at least one of the output angle scanning component or the input angle scanning component of the filter subsystem to guide the output beam to a selected output channel among two or more output channels.

21. The lighting system of claim 18, wherein the lighting source is a first lighting source of two or more lighting sources, and wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to: The angle of at least one of the output angle scanning component or the input angle scanning component of the filter subsystem is selected to receive light from a selected illumination source from two or more illumination sources as the input beam of the filter subsystem.

22. The lighting system of claim 18, further comprising: A horizontal axis angle scanning component for receiving the output beam of the filter subsystem from the output angle scanning component of the filter subsystem, wherein the scanning plane of the horizontal axis angle scanning component is orthogonal to the scanning plane of the output angle scanning component of the filter subsystem, wherein the output beam can be guided along any output angle by controlling the output angle scanning component and the horizontal axis angle scanning component of the filter subsystem.

23. The lighting system of claim 22, further comprising: A controller communicatively coupled to the input angle scanning component and the output angle scanning component, the controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: The output angle scanning component and the horizontal axis angle scanning component of the filter subsystem are modulated to modulate the output angle to reduce speckle.

24. The lighting system of claim 23, further comprising: A coupling lens is used to guide the output beam from the transverse angle scanning assembly to the input surface of the optical fiber, wherein the output angle scanning assembly and the transverse angle scanning assembly of the filter subsystem are modulated to modulate the output angle to modulate at least one of the position or angle of the output beam of the filter subsystem on the input surface of the optical fiber.

25. The lighting system of claim 17, wherein at least one of the input focusing optics or the output focusing optics of any one of the two or more tunable filters comprises: At least one of a parabolic mirror, an elliptical mirror, or a refractive scanning lens.

26. The lighting system of claim 17, wherein the linear variation filter of any one of the two or more tunable filters comprises: At least one of a linearly variable spectral filter, a linearly variable neutral density filter, a linearly variable polarizer, or a linearly variable waveplate.

27. The lighting system of claim 17, wherein at least one of the input angle scanning assembly or the output angle scanning assembly of any one of the two or more tunable filters comprises: At least one of a galvanometer, an acousto-optic deflector, an electro-optic deflector, a polygon scanner, or a microelectromechanical system deflector.

28. The lighting system of claim 17, wherein the lighting source comprises: At least one of a supercontinuum laser source, a laser-driven plasma source, or a laser diode.

29. The lighting system of claim 17, wherein the two or more tunable filters comprise: A first tunable filter, wherein the linearly varying filter of the first tunable filter includes a neutral density filter; A second tunable filter, wherein the linear variation filter of the second tunable filter includes a low-pass spectral filter; and A third tunable filter, wherein the linear variation filter of the third tunable filter includes a high-pass spectral filter.

30. The lighting system of claim 29, wherein the lighting source comprises: Supercontinuum laser source.

31. The lighting system of claim 17, wherein at least one of the input focusing optics or the output focusing optics of any one of the two or more tunable filters comprises: Parabolic mirror.

32. The lighting system of claim 17, wherein at least one of the input angle scanning assembly or the output angle scanning assembly of any one of the two or more tunable filters comprises: galvanometer.

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