Illumination device for microscopy

Abstract

An illumination device comprises one or more light sources each configured to generate a beam of light, one or more single-mode fibers each having a first end coupled to a respective one of the light source(s) and a second end opposite the first end, and a photonic lantern having one or more single-mode input ports and a multimode output port, each single-mode input port connected to the second end of a respective one of the one or more single-mode fibers. The photonic lantern is configured to receive, from the single-mode fiber(s), one or more single-mode light inputs each having one propagation mode associated therewith, to combine the one or more single-mode light inputs into one light output having one or more higher order propagation modes associated therewith, and to provide, via the multimode output port, the light output to an imaging setup for illumination of a sample under examination.

Description

ILLUMINATION DEVICE FOR MICROSCOPYCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of United States Provisional Patent Application No. 63 / 618,495 filed on January 8, 2024, the contents of which are hereby incorporated by reference.FIELD

[0002] The improvements generally relate to the field of imaging, and more particularly to illumination devices for microscopy.BACKGROUND

[0003] Microscopy is a key tool for drug development and biological research. While traditional drug development has focused on small molecules, promising new classes of therapeutic medicines such as biologies (e.g., Ribonucleic acid (RNA) therapeutics and antibody-drug conjugates) are being introduced. These approaches rely on targeted drug delivery methods and biological interactions that are more complex than small molecule therapeutics. Many of the features that must be investigated are on a subcellular scale, such as organelles and protein structures and are in the tens of nanometers. Microscopy provides high quality data but standard confocal microscopes have limited resolution due to the diffraction limit, which is larger than the sizes of many of the features of interest, and have limited contrast due to finite signal and background.

[0004] Super-resolution fluorescence microscopy (SRFM) is one solution that can image biological features with nanoscale resolution. In SRFM, one or more targets of interest are labelled with fluorophores and the microscope’s lasers control which fluorophores emit light. This emission light is then collected and measured by the microscope, effectively enabling a controlled smaller imaging spot that yields high resolution images. This approach is revolutionizing bioimaging, yielding unprecedented spatial detail down to the scale of biomolecular complexes (e.g., about tens of nanometers). STimulated Emission Depletion (STED), which is one of the leading SRFM techniques, has several key advantages overthe confocal microscope including improved resolution. However, despite the improvement in resolution, and intrinsic compatibility and similar workflow, STED instruments have yet to be widely adopted in place of confocal due to the high cost and complexity of commercial instruments. Indeed, SRFM requirestedious and extremely fine alignment of multiple beams on the target sample to control and image fluorophores, which in turn requires expensive and precise components.

[0005] Although fluorescence imaging techniques, which require sample staining and preparation, are widely used in live-cell imaging, they can often be toxic to the samples. Alternative approaches, named dark-field microscopy, enable the visualization of structures in biological samples with enhanced contrast without the need for staining. Dark-field microscopy employs oblique illumination and spatial filtering to selectively collect scattered and diffracted light from the sample while preventing unscattered light beams from being detected. This is achieved using a ring-shaped beam of light focused onto the specimen. The specimen scatters and diffracts the light, which is then collected by the microscope objective. The oblique illumination light that passes through the sample without deviation falls outside the collection cone of the objective, creating the characteristic dark background. While dark-field microscopy does not inherently overcome the diffraction limit of light, it is still considered as a super-resolution technique. It enables the visualization of structures smaller than the diffraction limit, down to a few tens of nanometers, due to the enhanced detection of scattered and diffracted light. However, dark-field microscopes face similar alignment challenges as SRFM. To achieve optimal imaging performance, the on-axis light detection system must be precisely co-aligned with the oblique ring-shaped illumination.

[0006] Thus, there is a need for improvement.SUMMARY

[0007] In accordance with one aspect, there is provided an illumination device comprising one or more light sources, each light source configured to generate a beam of light, one or more single-mode fibers, each single-mode fiber having a first end coupled to a respective one of the one or more light sources and a second end opposite the first end, and a photonic lantern having one or more single-mode input ports and a multimode output port, each single-mode input port connected to the second end of a respective one of the one or more single-mode fibers, the photonic lantern configured to receive, via the one or more single-mode fibers, one or more single-mode light inputs each having one propagation mode associated therewith, to combine the one or more single-mode light inputs into one light output having one or more higher order propagation modes associatedtherewith, and to provide, via the multimode output port, the light output to an imaging setup for illumination of a sample under examination.

[0008] In at least one embodiment in accordance with any previous / other embodiment described herein, the illumination device further comprises one or more fiber connectors connecting the one or more light sources to the photonic lantern via the one or more singlemode fibers.

[0009] In at least one embodiment in accordance with any previous / other embodiment described herein, the illumination device further comprises one or more polarization controllers coupled to a respective one of the one or more fiber connectors, each polarization controller configured to alter a polarization of light transmitted in the respective one of the one or more single-mode fibers connected to the respective one of the one or more fiber connectors.

[0010] In at least one embodiment in accordance with any previous / other embodiment described herein, the illumination device further comprises a few-mode fiber connected between the multimode output port of the photonic lantern and the imaging setup, and the photonic lantern is configured to provide the light output via the multimode output port for propagation in the few-mode fiber towards the imaging setup.

[0011] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to provide the light output via the multimode output port for propagation in free space towards the imaging setup.

[0012] In at least one embodiment in accordance with any previous / other embodiment described herein, the light output is provided to the imaging setup for illumination of the sample comprising one or more fluorophores, and a position of the light output relative to the sample is modulated to track the one or more fluorophores.

[0013] In at least one embodiment in accordance with any previous / other embodiment described herein, the one or more light sources comprise a first laser operating at a first wavelength and two second lasers each operating at a second wavelength different from the first wavelength, each of the first wavelength and the second wavelength being in one of the visible spectrum, the infrared spectrum, and / or the ultraviolet spectrum.

[0014] In at least one embodiment in accordance with any previous / other embodiment described herein, the first laser is configured to generate a fluorescence excitation beam, and the two second lasers are configured to generate a STimulated Emission Depletion (STED) beam.

[0015] In at least one embodiment in accordance with any previous / other embodiment described herein, the one or more light sources comprise a laser configured to generate a fluorescence excitation beam, and the one or more single-mode fibers comprise a first single-mode fiber and a second single-mode fiber, the illumination device further comprising a beam splitter connected to the laser, the first single-mode fiber, and the second single-mode fiber, the beam splitter configured to split the excitation beam into a transmitted beam guided through the first single-mode fiber and a reflected beam guided through the second single-mode fiber.

[0016] In at least one embodiment in accordance with any previous / other embodiment described herein, backscattered light and / or fluorescent light emitted from the sample in response to the illumination thereof is guided through the photonic lantern and through the one or more single-mode fibers.

[0017] In at least one embodiment in accordance with any previous / other embodiment described herein, the illumination device further comprises one or more light detectors and one or more circulators, each light detector coupled to a respective one of the one or more single-mode fibers via a respective circulator, the one or more light detectors configured to detect the backscattered light and / or the fluorescent light.

[0018] In at least one embodiment in accordance with any previous / other embodiment described herein, the one or more light detectors are further configured to one of spectrally and spatially filter the backscattered light and / or the fluorescent light.

[0019] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to combine the one or more singlemode light inputs into the light output having one or more linearly polarized (LP) propagation modes associated therewith.

[0020] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to combine the one or more single-mode light inputs into the light output having at least one of a fundamental LP mode and one or more higher order LP modes associated therewith.

[0021] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to combine the one or more singlemode light inputs into the light output having associated therewith at least two orthogonal propagation modes having unequal power levels.

[0022] In at least one embodiment in accordance with any previous / other embodiment described herein, the illumination device further comprises at least one polarizing controller configured to adjust the power level associated with at least one of the at least two propagation modes.

[0023] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to provide the light output to the imaging setup comprising a microscope.

[0024] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is configured to provide the light output to the imaging setup comprising a super-resolution microscope.

[0025] In at least one embodiment in accordance with any previous / other embodiment described herein, the photonic lantern is a mode selective photonic lantern (MSPL).

[0026] In at least one embodiment in accordance with any previous / other embodiment described herein, each light source has an input power, a polarization, and a wavelength associated therewith, and the one or more light sources are connected at an input thereof to a controller configured to provide a control signal to each light source for adjusting at least one of the input power, the polarization, and the wavelength to control an intensity distribution of the light output.

[0027] Many further features and combinations thereof concerning embodiments described herein will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE FIGURES

[0028] In the figures,

[0029] Fig. 1A is a schematic diagram of an example of an imaging system, in accordance with one embodiment;

[0030] Fig. 1 B is a detailed schematic diagram of the imaging system of Fig. 1A, in accordance with one embodiment;

[0031] Fig. 2A is a schematic diagram of the illumination device of Fig. 1A, in accordance with one embodiment;

[0032] Fig. 2B is a schematic diagram showing free space used as the connections in the illumination device of Fig. 2A, in accordance with one embodiment;

[0033] Fig. 2C is a schematic diagram showing fiber connectors used as the connections in the illumination device of Fig. 2A, in accordance with one embodiment;

[0034] Fig. 2D is a schematic diagram showing fiber connectors and polarization controllers used as the connections in the illumination device of Fig. 2A, in accordance with one embodiment;

[0035] Fig. 3A illustrates the intensity pattern generated by the illumination device of Fig. 2A, in accordance with one embodiment;

[0036] Fig. 3B illustrates the resolution enhancement achieved using the illumination device of Fig. 2A, in accordance with one embodiment;

[0037] Fig. 4A is a schematic diagram of the illumination device of Fig. 1A, in accordance with another embodiment;

[0038] Fig. 4B illustrates the intensity pattern generated by the illumination device of Fig. 4A, in accordance with one embodiment;

[0039] Fig. 4C illustrates the emitter intensity and localization for the illumination device of Fig. 4A, based on the minimal photon fluxes (MINFLUX) technique, in accordance with one embodiment;

[0040] Fig. 5 is a schematic diagram of the illumination device of Fig. 1A, in accordance with yet another embodiment; and

[0041] Fig. 6 is a block diagram of an example computing device, in accordance with one embodiment.

[0042] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.DETAILED DESCRIPTION

[0043] There is described herein an illumination device configured to be integrated or coupled to an imaging system, such as an imaging system for super-resolution imaging (i.e., imaging that breaks the diffraction limit and offers resolution down to the nanometer scale ), and other light-based imaging techniques. The imaging system may be used for any suitable application, including, but not limited to, super-resolution fluorescence microscopy, dark-field microscopy, and / or fully contained endoscope applications. In some embodiments, the illumination device may be coupled to a fluorescence microscope. The illumination device may, in some preferred embodiments, plug directly into the illumination path of a scanning optical microscope (e.g., a confocal microscope).

[0044] Fig. 1 A illustrates an example of an imaging system 100, in accordance with one embodiment. The imaging system 100 comprises a control unit 102, an illumination device 104, and an imaging setup 106. Although not illustrated, it should be understood that the imaging system 100 may, in some embodiments, comprise one or more additional components (e.g., optical components).

[0045] As will be described further below, the control unit 102 is configured to control the operation of the illumination device 104, which connects to the imaging setup 106 to provide thereto a light beam (referred to herein as “multimode light”, an “excitation beam”, or “light output”) that is projected onto a sample (reference 107 in Fig. 1 B) for illumination thereof. The sample 107, once illuminated, is imaged using the imaging setup 106. In some embodiments, the sample 107 may comprise biological tissue, provided in either in vivo or ex vivo conditions. In some embodiments, fluorophores may be attached to target molecules in the sample 107, which are then visualized using the imaging setup 106. In one embodiment, the photophysical state of the fluorophores may be manipulated using the light beam output by the illumination device 104.

[0046] Referring now to Fig. 1 B, in one embodiment, the imaging setup 106 comprises a microscope 108 used to examine the sample 107, and a light detector (also referred toherein as a “photodetector”) 110. The light detector 1 10 may comprise any suitable detector (such as a photodiode or a camera) configured to receive, collect, and measure light backscattered from the sample 107 in response to illumination of the sample 107 with the light beam output by the illumination device 104. In some embodiments, the light detector 110 is configured to carry out processing or post-processing of the light received from the sample 107. In some embodiments, the light detector 110 may implement analog- to-digital (ADC or A / D) conversion of the received light prior to transmission, e.g., to a computing device (not shown) communicatively coupled thereto via any suitable communication link (e.g., wired and / or wireless) and configured to perform analysis of the data received from the light detector 1 10. In some embodiments, the light detector 110 may be partially or wholly integrated into the computing device. In some embodiments, the imaging setup 106 may be further configured to filter (e.g., spatially or spectrally) the light received by the light detector 110. In some embodiments, the illumination device 104 may also be configured to measure the light backscattered from the sample 107.

[0047] Referring now to Fig. 2A, the illumination device 104 will now be described in accordance with one embodiment. As will be described further below, operation of the illumination device 104 is controlled by a controller 202 which is part of the control unit 102. The illumination device 104 comprises one or more light sources as in 204i, 2042, 2043 and a beam shaping device 208. The illumination device 104 may further optionally comprise one or more connections as in 206i, 2062, 2063 (described further below with reference to Fig. 2B, Fig. 2C, and Fig. 2D) used to interconnect the light sources as in 204i, 2042, 2043 and the beam shaping device 208, via a first set of single-mode fibers 205i, 2052 , 2053 and a second set of single-mode fibers 207i, 2072 , 2073. The beam shaping device 208 then provides its output to a few-mode fiber 210 which connects directly to the imaging setup 106 (e.g., into the illumination path of the microscope 108 of Fig. 1 B). As can be seen from Fig. 2A, the illumination device 104 is free of moving parts and only requires connections to the controller 202 and to the imaging setup 106, thus allowing for a simplified design.

[0048] As used herein, the term “single-mode fiber” (or SMF) refers to an optical fiber which is configured to only allow transmission of a single propagation mode of light. This is in contrast to a “multimode fiber” (or MMF), which refers to an optical fiber which is configured to allow multiple propagation modes of light to be transmitted. As used herein,the term “few-mode fiber) (or FMF) refers to a MMF which is configured to allow transmission of only a few propagation modes of light (e.g., higher order modes).

[0049] As used herein, the term “mode”, “propagation mode”, or “light mode” refers to one of the possible orthogonal electromagnetic field configurations that are guided in a fiber. Linearly polarized (LP) propagation modes (e.g., the fundamental LP01 mode and / or one or more higher order modes) are illustratively provided in the embodiments illustrated and described herein. For example (and as illustrated in Fig. 2A), the first connection 206i may provide the LP01 mode at the output port 213b of the photonic lantern 208 (described further below), and the second and third connections 2062, 2063 may provide the two degenerate LP1 1 modes, with the second connection 2062 providing the LP11 a mode at the output port 213b, and the third connection 2063 providing the LP1 1 b mode at the output port 213b. It should however be understood that more propagation modes (e.g., three (3) or more modes including, but not limited to, LP01 , LP1 1 , and LP21) or any combination of propagation modes may apply depending on the application. For example, higher order propagation modes may be used to improve and / or parallelize the imaging process (e.g., modifying the intensity gradient in two-photon STED). As such, although reference is made herein to the sample 107 being illuminated with multimode light, it should be understood that illumination of the sample 107 with selected higher order propagation modes may also apply. In particular, any suitable number of higher order propagation modes may be exploited for illumination. For example, two higher order propagation modes may be combined to obtain a doughnut-shaped pattern. It should also be understood that, in some embodiments, only the two degenerate LP11 modes (LP11 a and LP11 b) may apply. As a result, the illumination device 104 may be configured to generate an output intensity distribution with one node or multiple nodes (e.g., a doughnut-shaped pattern with a zero node at the center). Alternatively, a single (i.e. fundamental) propagation mode or higher order propagation mode may be used for other imaging applications including, but not limited to, confocal microscopy or structured illumination microscopy.

[0050] As used herein, the term “path” or “light path” refers to the physical channel through which light propagates. This can be confined propagation in optical systems, such as in fiber optics, or through a fiber input directed towards the beam shaping device 208. Alternatively, a light path can also describe free-space propagation, where the light travels through an open medium (e.g., air or vacuum) along a defined propagation axis. The lightpath encompasses the entire trajectory where light travels, including where light enters, propagates, and potentially exits the optical system. This definition applies regardless of whether the medium is confined (e.g., like a waveguide) or open (e.g., like a laser beam in free space).

[0051] Still referring to Fig. 2A, in the illustrated embodiment, the illumination device 104 comprises three (3) light sources (e.g., lasers) 204i, 2042, and 204s each connected, via a respective one of the first set of (e.g., three (3)) single-mode optical fibers 205i, 2052, and 205s, to the beam shaping device 208. Optionally, each of the three (3) single-mode optical fibers 205i, 2052, and 2053 may be coupled at a first (or proximal) end to a respective one of the light sources 204i, 2042, and 204s, and at a second (or distal) end opposite to the first (or proximal) end to the input of a respective one of three (3) connections 206i, 2062, and 2063, and the beam shaping device 208 may be coupled to the outputs of the connections 206i, 2062, and 2063 via the second set of (e.g., three (3)) single-mode optical fibers 207i, 2072, and 207s.

[0052] It should however be understood that any suitable number of components other than three (3) may apply. The illumination device 104 illustrated in Fig. 2A may indeed be used with one color or used with a variety of colors, over the visible, infrared (near-infrared and mid-infrared), and / or ultraviolet spectrum, in orderto perform multi-color imaging (e.g., super-resolution or standard imaging). It should thus be understood that, although the illumination device 104 is illustrated herein as comprising three (3) light sources 204i, 2042, and 204s (and accordingly three (3) single-mode fibers 205i, 2052, and 205s, three (3) single-mode fibers 207i, 2072, and 207s, and three (3) connections 206i, 2062, and 2063), any suitable number of components may apply. For example, the illumination device 104 may comprise a single light source, as will be described further below with reference to Fig. 4A, or two (2) light sources. Depending on the application, the illumination device 104 may also be used to perform microscopy with a beam shaping device 208 having any suitable number of propagation modes associated therewith, including, but not limited to, four (4) modes, five (5) modes, six (6) modes, seven (7) modes, or eight (8) modes. As such, other embodiments than the ones illustrated herein may apply.

[0053] Still referring to Fig. 2A, in one embodiment, each light source 204i, 2042, 204s illustratively comprises a single-mode input port 211 a connected to the controller 202 and a single-mode output port 21 1 b connected to a respective single-mode fiber 205i, 2052,205s. It should however be understood that the light sources 204i, 2042 , 204s may comprise any suitable number of single-mode input ports 211 a and single-mode output ports 211 b, depending on the application. In addition, although one input port 21 1 a and one output port 211 b are illustrated in Fig. 2A in relation to the first light source 204i, it should be understood that this is for sake of simplicity and that each light source 204i, 2042, 2043 has a single-mode input port 211 a and a single-mode output port 211 b associated therewith.

[0054] The controller 202 is configured to individually control each light source 204i, 2042, 2043 (e.g., by providing a control signal thereto) in order to cause the light source 204i, 2042, 2043 to emit a beam of single-mode light having an adjustable output intensity distribution (or intensity pattern). The controller 202 may be configured to control the intensity distribution produced at the output of the illumination device 104 (i.e. at the output of the beam shaping device 208) by adjusting (or modulating) the input power, the polarization, and / or the wavelength associated with each light source 204i, 2042, 2043. The beam of single-mode light generated by each light source 204i, 2042, 204s is then provided, via the respective fiber 205i, 2052, 2053, as an input to the beam shaping device 208, optionally via a respective connection 206i, 2062, and 2063 as described above.

[0055] Although reference is made herein to each light source 204i, 2042, 204s emitting a beam of single-mode light, it should be understood that, in other embodiments, one or more the light sources 204i, 2042, 2043 may each be configured to emit a beam of multimode light with each single-mode fiber 205i, 2052 , 205s allowing for only a single propagation mode associated with the beam of multimode light to be input into the beam shaping device 208.

[0056] In one embodiment, the first light source 204i is a laser configured to operate at a first wavelength and to emit a fluorescence excitation beam, while each of the second and third light sources 2042, 204s is a laser configured to operate at a second wavelength and to emit a doughnut-shaped pattern referred to herein as a “STED beam”. While reference is made herein to the light sources 204i, 2042, 204s being lasers, it should be understood that any suitable light source 204i, 2042, 204s other than a laser may apply. For example, in some embodiments, a diode may be used as one or more of the light sources 204i, 2042, 204s. In addition, it should be understood that the pattern (as well as the light emitted by each light source 204i, 2042, 204s) may be pulsed or illuminatedcontinuously over times. This results in the combined projection of a center laser spot at the first wavelength and a doughnut-shaped pattern at the second wavelength. Any suitable wavelength within the visible spectrum (e.g., between about 400 nm and about 750 nm), the infrared (near-infrared and mid-infrared) spectrum, and / or the ultraviolet spectrum may be used for each of the first wavelength and the second wavelength. For example, the first wavelength and the second wavelength may be any wavelength including, but not limited to, 405 nm, 425 nm, 488 nm, 514 nm, 561 nm, 633 nm, 640 nm, 647 nm, 650 nm, 732 nm, 750 nm. In one embodiment, the second wavelength is longer (i.e., greater) than the first wavelength. For example, the first wavelength may be 650 nm and the second wavelength may be 750 nm. Other embodiments may apply.

[0057] Referring now to Fig. 2B, in one embodiment, the connections as in 206i, 2062, 2063 interconnecting the light sources 204i, 2042, 204s and the beam shaping device 208 involve direct splicing between the first set of single-mode fibers 205i, 2052, 205s and the second set of single-mode fibers 207i, 2072, 207s. It should however be understood that the illumination device 104 may comprise any suitable connection(s) as in 2061, 2062, 2063 including, but not limited to, splicing, fiber connector(s), polarization controller(s) (also referred to herein as polarization filter(s) or polarizing filter(s)), and any other suitable coupling device(s). Although not illustrated, it should also be understood that, in yet other embodiments, the connections 206i, 2062, 2063 may involve free space.

[0058] For example, Fig. 2C illustrates an embodiment in which the connections 206i, 2062, and 2063 comprise fiber connectors 212i, 2122, 212s. Each fiber connector 212i, 2122, 2123 has a single-mode input port 214a (also referred to herein as a “fiber input”) connected to a respective single-mode fiber 205i, 2052 , 205s and a single-mode output port 214b (also referred to herein as a “fiber output”) connected to the beam shaping device 208 (i.e. to single-mode inputs thereof, not shown) via a respective single-mode fiber 207i, 2072, 207s. Although one input port 214a and one output port 214b are illustrated in Fig. 2C in relation to the first fiber connector 212i (and similarly in Fig. 4A described further below), it should be understood that this is for sake of simplicity and that each fiber connector 212i, 2122, and 2123 has an input port 214a and an output port 214b associated therewith. In the illustrated embodiment, each single-mode fiber 207i, 2072, 2073 is a mode-selective optical fiber device designed for visible wavelengths and configured to guide therein a given propagation mode, and all single-mode fibers 207i, 2072, 2073 are brought through the beam shaping device 208.

[0059] Fig. 2D illustrates another embodiment, where the connections (references 206i, 2062, 2063 in Fig. 2A) of the illumination device 104 comprise a first plurality of fiber connectors as in 2161, 2162, 2163, (each coupled to a respective one of the single-mode fibers 205i, 2052, 205s), a second plurality of fiber connectors 217i, 2172, 21 ?3 (coupled to the single-mode input of the beam shaping device 208), and a plurality of polarization controllers 2181, 2182, 2183. Although the polarization controllers 218i, 2182, 2183 are illustrated as being part of (i.e. integrated into) the connections 206i, 2062, 2063, it should be understood that the polarization controllers 2181, 2182, 2183 may be external to the connections 206i, 2062, 2063 and connected thereto. Each polarization controller (e.g., polarization controller 2181) is coupled, via a single-mode fiber 219, to the output of a respective fiber connector (e.g., fiber connector 216i) from the first plurality of fiber connectors and to the input of a respective fiber connector (e.g., fiber connector 217i) from the second plurality of fiber connectors. As understood by those skilled in the art, each polarization controller (e.g., polarization controller 2181) is configured to alter the polarization of the light transmitted in the respective first single-mode fiber 219 coupled to a respective fiber connector (e.g., fiber connector 2161). This is achieved by wrapping the fiber 219 around two spools or three spools (as shown in Fig. 2D) to create independent wave plates that will alter the polarization of the light. The spools may achieve fiber loops having any suitable diameter, depending on the application. Each polarization controller 2181, 2182, 2183 can generate every polarization state of the Poincare sphere within the respective single mode fiber 219. Ultimately, the polarization controller 2181, 2182, 2183 manages the polarization of the light (in the fundamental propagation mode or the high- order propagation modes) at the output of the illumination device 104.

[0060] Referring back to Fig. 2A, the beam shaping device 208 is configured to receive one or more single-mode light inputs via its single-mode input ports 213a (which are connected to respective light sources 204i, 2042 , 204s through the single-mode fibers 205i, 2052, 205s), and optionally via the connections 206i, 2062, 2063. The beam shaping device 208 is further configured to perform a conversion from single-mode to multimode (i.e. to convert the one or more single-mode light inputs into a single light output having associated therewith one or more higher-order modes comprising at least two orthogonal propagation modes), and to provide the light output at its multimode output port 213b. The multimode output port 213b of the beam shaping device 208 is connected to the few-mode fiber 210, which may be connected to an imaging head of the imaging system 106 (e.g.,a scanning optical microscope such as a confocal microscope) to emit and collect light. In one embodiment, the beam shaping device 208 is configured to output multimode light for propagation in the few-mode fiber 210, the multimode light comprising at least two orthogonal light modes (e.g., a fundamental propagation mode and at least one higher order propagation mode orthogonal to the fundamental mode). Each orthogonal light mode of the multimode light has a given power level associated therewith. The power levels may be unequal, such that the power level associated with one of the light paths may be greater than the power level associated with remaining ones of the light paths. Any suitable means may be used to adjust the power level in one or more of the light paths.

[0061] In one embodiment, the polarization controllers 2181, 2182, 2183 described above with reference to Fig. 2D may be used to adjust the power level. For example, a given one ofthe polarization controllers 2181 , 2182, 2183 (e.g., polarization controller 2183) may be configured to independently adjust the power level associated with a center one of the light paths (e.g., when the multimode light comprises three (3) light paths).

[0062] In another embodiment, the power level may be controlled using a fiber-based acoustic optical modulator (AOM) or acousto-optics tunable filter (AOTF) for wavelength and power control. In yet another embodiment, free space components or a software and / or hardware configuration involving fiber optics (e.g., a fiber-based polarization controller) may be used to directly alter the output of the light sources 204i, 2042, 2043 and thus adjust the power level in one or more of the light paths. Other embodiments may apply.

[0063] While a few-mode fiber 210 is illustrated and described herein as being connected to the multimode output port 213b of the beam shaping device 208, it should be understood that, in some embodiments, no few-mode fiber as in 210 may be provided and the multimode light may be output via the multimode output port 213b for propagation in free space towards the imaging system 106.

[0064] Fig. 3A illustrates the intensity pattern 300 of the excitation beam generated by the illumination device 104 of Fig. 2A and provided to the sample (reference 107 in Fig. 1 B) being examined by the imaging setup 106. The intensity pattern 300 shows the center LP01 laser spot 302 and the LP1 1 doughnut-shaped pattern 304. When the sample 107is illuminated, the illuminated spot from the LP01 light path of the beam shaping device 208 is centered concentrically within the illuminated spot from the LP11 light path of the beam shaping device 208. In some embodiments, the illuminated spot may be displaced with respect to the sample 107, using any suitable means.

[0065] In one embodiment, the beam shaping device 208 is a photonic lantern. A photonic lantern is understood to be a fiber coupler that adiabatically merges several single-mode waveguides into one multimode waveguide (e.g., through fusing and tapering). In other words, the photonic lantern is an N-by-one fiber optic component that maps the propagation modes of a bundle of N single-mode fibers (SMFs) to the modes of a multimode structure. In one embodiment, the beam shaping device 208 is a mode- selective photonic lantern (MSPL) that takes multiple light inputs from the light sources 204i, 2042, and 204s and combines them into a single output within a fiber optic cable, which can be inserted directly into the laser illumination port of a scanning optical microscope. In particular, the MSPL emits two or more modes in a concentric pattern. The MSPL is a variant of the photonic lantern that has little or no crosstalk and is ideal for mode control. It provides a low-loss interface between single-mode and multimode for a large bandwidth (e.g., > 100 nm) and allows parallel measurement and control on mode propagation. One example embodiment of such a photonic lantern is described in International Patent Application Publication No. WO 2021 / 151194 A1 , the entire contents of which are incorporated herein by reference. In some embodiments, the photonic lantern is implemented using the embodiments described in International Patent Application Publication No. WO 2019 / 148276, the entire contents of which are incorporated herein by reference. A MSPL is a sub-category of photonic lanterns that features a one-to-one mapping between individual SMFs and LP modes of a multimode fiber. The modal mapping does not depend on the excitation wavelength, making MSPLs wavelength independent.

[0066] In one embodiment, the MSPL that is used as part of the illumination device 104 has the ability to discriminate between modes, e.g., up to about 30 dB, ensuring there is effectively no crosstalk between the light in the doughnut-shaped pattern and the center spot, an essential property for STED where the laser powers in the two output intensity distributions are precisely controlled. Additionally, the MSPL may achieve the production of output intensity distributions in an ultrashort illumination device (i.e. within a range between about 2 mm and about 5 mm, as opposed to about tens of centimeters forconventional techniques), allowing to develop devices respecting the adiabatic criterion, resulting in quasi-lossless devices (i.e., having an insertion loss lower than about 0.5 dB, as opposed to several dB for conventional techniques). Thus, the MSPL used herein may pass the necessary laser frequencies with little cross talk, produce two or more output intensity distributions used for STED at desired frequencies, and produce the necessary output intensity distributions at multiple frequencies in the visible spectrum, the intensity patterns being positioned concentrically as required for STED.

[0067] While reference is made herein to a photonic lantern, and more specifically an MSPL, being used as the beam shaping device 208, it should be understood that any suitable technique or device may apply. For example, a non-coupling fiber component (i.e., null coupler) that adiabatically merges several single-mode waveguides into one multimode waveguide and is designed in accordance with the desired characteristics of the illumination device 104 may be used.

[0068] Fig. 3B illustrates a plot 310 showing the resolution enhancement achieved using the systems and method described herein on a standard sample (also referred to as a “nanoruler super-resolution calibration kit”) consisting of fluorophores (e.g., ATTO- 647N fluorophores) separated on DNA origami scaffolds by 120 nanometers. The sample is first (see image 312) illuminated with the LP01 excitation beam as a regular confocal image and then (see image 314) illuminated with the co-aligned LP01 excitation and doughnut-shaped depletion beam composed of the two LP11 modes from the illumination device. Image 312 shows a clear resolution enhancement with a decrease by a factor of about two (2) of the width of the point-spread function, i.e. the width of the spot (or “dot”) of light coming from the fluorescent sample. The inlets 3161, 3181 at the bottom of the image 312 and the inlets 3162, 3182 at the bottom of the image 314 respectively show two zoomed regions of interest (labelled A and B on the images 312, 314) where the resolution enhancement of two distinct light emitters (image 312) superimposed on the image 314 can be seen.

[0069] Referring now to Fig. 4A, the illumination device 104 will now be described in accordance with another embodiment. The illumination device 104 illustrated in Fig. 4A may be used to achieve one-color super-resolution. For this purpose, the illumination device 104 illustrated in Fig. 4A comprises a single light source 402, a variable beam splitter 404, a first fiber input 406i, a second fiber input 4062, a first single-mode fiber 408i,a second single-mode fiber 4082, a first fiber connector 41 O-i, a second fiber connector 4102, a beam shaping device 412 (e.g., an MSPL as described herein above or a non- mode-selective photonic lantern), and a few-mode fiber 414.

[0070] The light source 402 may be a time-varying light source used to create a dynamic (i.e. moving) excitation pattern. Alternatively, the light beam used to illuminate the sample (reference 107 in Fig. 1 B) may be moved relative to the sample by translating either the light beam or the sample 107 itself. In one embodiment, the light source 402 is a laser having a single-mode input port 415a connected to a controller 416 and a singlemode output port 415b connected to the beam splitter 404. The operation of the light source 402 is controlled by the controller 416 in order to cause a fluorescence excitation beam to be output at the output port 415b.

[0071] The beam splitter 404 is configured to split the excitation beam generated by the light source 402 into a transmitted beam which is directed to the first fiber input 406i and a reflected beam which is directed to the second fiber input 4062. Each of the first and the second fiber input 406i, 4062 is in turn connected, via a respective single-mode fiber 408i, 4082, to the input of a respective fiber connector 410i, 4102. The beam shaping device 412 is coupled (via its single-mode input ports 418a) to the outputs of the fiber connectors 410i, 4102 and provides (via its multimode output port 418b) its output to the few-mode fiber 414 which connects to the imaging setup 106 (e.g., into the illumination path of the microscope 108 of Fig. 1 B). In particular, each fiber connector 410i, 4102 illustratively comprises a single-mode input port 417a connected to a respective single-mode fiber 408i, 4082, and a single-mode output port 417b connected to the beam shaping device 412 via a respective single-mode fiber 411 i, 41 12. In the illustrated embodiment, the two degenerate LP1 1 modes are provided via the single-mode output port 417b of each fiber connector 410i, 4102. The single-mode output fibers 4111, 4112 are then brought through the beam shaping device 412 which provides a multimode output at the multimode output port 418b thereof, the multimode output port 418b being connected to the few-mode fiber 414.

[0072] Fig. 4B illustrates the intensity pattern 420 of the excitation beam generated by the illumination device 104 of Fig. 4A and provided to the sample 107. The intensity pattern 420 shows the LP1 1 doughnut-shaped pattern 422. In the embodiment illustrated in Fig. 4A, the illumination spot can be modulated regarding spatial position, polarization, orshape, e.g., by temporally changing the beam’s position relative to an emitter. For example, the position of the excitation beam relative to the sample 107 is updated such that the excitation beam is centered on fluorophore(s) of the sample 107, or the excitation beam is scanned across the sample 107 for imaging or tracking of said fluorophore(s). Fig. 4C illustrates the emitter intensity and localization for the illumination device 104 of Fig. 4A, based on the MINFLUX technique. As can be seen from Fig. 4C, the resulting fluorescence emission from a single molecule near the excitation spot can be correlated with the position of the beam to extract the emitter’s position. By modifying the beam’s position relative to the sample, it becomes possible to track an emitter or localize multiple emitter positions. Furthermore, the fluorescence emission intensity can be correlated to the illumination spot’s polarization to measure the emitter’s orientation.

[0073] Referring now to Fig. 5, the illumination device 104 will now be described in accordance with yet another embodiment, in which light is collected and recorded through the illumination device 104. In particular, in the embodiment shown in Fig. 5, the illumination device 104 is configured to receive, collect, and measure the light backscattered from the sample (reference 107 in Fig. 1 B). Similarly to the illumination device 104 of Fig. 2A, the illumination device 104 of Fig. 5 comprises one or more (e.g., up to three (3)) light sources (e.g., lasers) 204i, 2042, and 204s each connected, via a respective one of one or more (e.g., up to three (3)) single-mode optical fibers 205i, 2052, and 205s, to a respective single-mode input (not shown) of the beam shaping device 208. The beam shaping device 208 provides its output to the few-mode fiber 210 which connects to the imaging setup 106. In particular, the few-mode fiber 210 is configured to emit light into the illumination path of the microscope (reference 108 of Fig. 1 B) and towards the sample 107, and to receive, from the collection path of the microscope 108, light from the sample 107 (either fluorescence or backscattered light). For this purpose, the illumination device 104 of Fig. 5 comprises one or more (e.g., up to three (3)) circulators 502i, 5022, and 502s interposed between the outputs of the single-mode optical fibers 205i, 2052, and 205s and the single-mode input of the beam shaping device 208.

[0074] One or more (e.g., up to three (3)) light detectors 504i, 5042, 504s are further provided, with the input of each light detector 504i, 5042, 504s being connected to a respective one of the circulators 502i, 5022, 502s via a respective one of one or more (e.g., up to three (3)) fibers 506i, 5062, 5063. It should be understood that each fiber 506i, 5062, 5063 may be a single-mode fiber or a multimode fiber. The light detectors 504i, 5042, 504smay comprise any suitable detector (such as a photodiode, photomultiplicator tubes, or a camera) configured to detect (i.e. receive, collect, and measure) the light from the sample 107 (fluorescence or backscatter). In some embodiments (and similarly to the light detector 110 described herein above with reference to Fig. 1 B), each light detector 504i, 5042, 504s may be configured to carry out processing or post-processing of the received light. For example, each light detector 504i, 5042, 5043 may implement ADC conversion of the received light.

[0075] As used herein, the term “circulator” refers to a non-reciprocal, passive device that conveys light between multiple ports in a specific direction in an optical fiber. The circulator ensures that light entering one port exits through the next port in a cyclic order. In the embodiment of Fig. 5, each circulator 502i, 5022, 502s has three (3) ports, labelled “1 ”, “2”, and “3” (see circulator 502s), with port 1 being coupled to a respective one of the light sources 204i, 2042, 204s (via a respective one of the single-mode optical fibers 205i, 2052 , 205s), port 2 being coupled to the single-mode input of the beam shaping device 208 (via a respective one of the single-mode fibers 207i, 2072, 207s), and port 3 being coupled to the input of a respective light detector 504i, 5042, 5043 (via a respective one of the fibers 506i, 5062, 506s). In each circulator 502i, 5022, 502s, light circulates from port 1 to port 2, and from port 2 to port 3.

[0076] The addition of the circulators 502i, 5022, 502s allows for both illumination and collection with any of the propagation modes (e.g., LP01 , LP11 a, or LP11 b) guided in the respective fibers 207i, 2072, 2073. In the illustrated example, the circulator 502i allows for both illumination and collection with the LP01 mode, the circulator 5022 allows for both illumination and collection with the LP11 a mode, and the circulator 5023 allows for both illumination and collection with the LP11 b mode. Following illumination of the sample 107, the backscattered light is coupled into the few-mode fiber 210 which guides therein one or more propagation modes associated with the backscattered light. The propagation modes are then separately extracted from the few-mode fiber 210 to the individual singlemode fibers 207i, 2072, 207s using the beam shaping device 208. The light coming from each propagation mode can then be separately detected using a respective one of the light detectors 504i, 5042, 504s. In the illustrated example, the light detector 504i is configured to detect the light coming from the LP01 mode guided through fiber 506i, the light detector 5042 is configured to detect the light coming from the LP11 a mode guidedthrough fiber 5062, and the light detector 5043 is configured to detect the light coming from the LP11 b mode guided through fiber 5063. Other embodiments may apply.

[0077] Fig. 5 shows a full illumination and detection setup that can be used for various applications including, but not limited to, for performing dark-field illumination, STED, and MINFLUX. In one embodiment, the illumination device 104 illustrated in Fig. 5 may indeed be used in dark-field imaging applications, e.g., for dark-field microscopy. In this case, one or more of the light sources 204i, 2042, 204s may be configured (e.g., controlled by the control unit, reference 102 in Fig. 1A) to generate simultaneous angled (i.e. oblique) illumination at different wavelengths. For example, two light sources (e.g., two lasers) as in 204i 2042 may be used to generate single-mode light for illuminating the sample 107. Alternatively, a single light source (e.g., a split laser) as in 204i may be used to illuminate the sample 107 at an angle (i.e. from the side) using higher order modes. The light beam generated by each of the one or more light source(s) 204i, 2042, 204s is routed to port 1 of a respective circulator 502i, 5022, 502s via the respective single-mode optical fiber 205i, 2052, 2053. The light then circulates from port 1 to port 2 of the respective circulator 502i,5022, 5023 and is guided, through the respective single-mode fiber 207i, 2072 , 2073 towards the single-mode input of the beam shaping device 208. The beam shaping device 208 then outputs multimode light which propagates in the few-mode fiber 210 for illuminating the sample 107. In particular, a ring-shaped beam of light is focused onto the sample 107 via the imaging setup 106.

[0078] The light scattered and diffracted by the sample 107 is then collected by the objective of the microscope 108, and the oblique illumination light which passes through the sample 107 without deviation falls outside of the collection cone of the microscope’s objective, thereby creating the dark background used in dark-field microscopy. The backscattered light is thus selectively collected while preventing undesired light (e.g., unscattered light beams) from being detected. The backscattered light is guided through the beam shaping device 208 via the few-mode fiber 210, and through the respective single-mode fibers 207i, 2072, 2073towards port 2 of the respective circulators 502i, 5022,5023. The light then circulates from port 2 to port 3 of each respective circulator 502i , 5022, 5023 and is guided through the respective fiber 506i, 5062, 5063 towards the respective light detector 504i, 5042, 5043.

[0079] In some embodiments, the output of each light detector 504i, 5042, 504s is communicatively coupled (via any suitable wired and / or wireless communication link) to a signal acquisition unit 508 configured to process (e.g., using any suitable processing means) and perform analysis of the data received from the light detectors 504i, 5042, 504s. In some embodiments, the signal acquisition unit 508 may be configured to filter (e.g., spatially or spectrally) and measure the light backscattered by the sample 107 and detected by the light detectors 504i, 5042, 504s. The result(s) of the processing and / or analysis performed by the signal acquisition unit 508 may be output in any suitable manner (e.g., displayed on an output device, such as a screen, associated with the signal acquisition unit 508). It should however be understood that, in some embodiments, the functionality of the signal acquisition unit 508 may be partially or wholly integrated into the light detectors 504i, 5042, 5043Such that the signal acquisition unit 508 may be omitted.

[0080] With reference to Fig. 6, part or all of the embodiments of the devices, systems and methods described herein may be implemented in a combination of both hardware and software. Fig. 6 illustrates an example computing device 600 which may be used to implement the imaging system 100 of Fig. 1A (e.g., the control unit 102 and / orthe imaging setup 106). The computing device 600 comprises a processing unit 602 and a memory 604 which has stored therein computer-executable instructions 606. The processing unit 602 may comprise any suitable devices configured to implement the functionality of the imaging system 100 such that instructions 606, when executed by the computing device 600 or other programmable apparatus, may cause the functions / acts / steps performed by the imaging system 100 as described herein to be executed. The processing unit 602 may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, custom-designed analog and / or digital circuits, or any combination thereof.

[0081] The memory 604 may comprise any suitable known or other machine-readable storage medium. The memory 604 may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory 604 may include a suitable combination of any type of computer memory that is located either internally or externally to device, forexample random-access memory (RAM), read-only memory (ROM), compact disc readonly memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory 604 may comprise any storage means (e.g., devices) suitable for retrievably storing machine- readable instructions 606 executable by processing unit 602.

[0082] The computing device 600 may be any suitable computing device, such as a desktop computer, a laptop computer, a mainframe, a server, a distributed computing system, a portable computing device, a mobile phone, a tablet, or the like.

[0083] In some embodiments, by eliminating the need for expensive optical components that require alignment and calibration, the illumination device described herein may allow to circumvent the complicated alignment procedures of STED and may allow to achieve a smaller footprint for the microscope, thus significantly reducing costs and simplifying use compared to existing techniques. In addition, the proposed device may be used to achieve imaging at multiple wavelengths (i.e., it is wavelength agnostic) without recalibration and may be available in a smaller form factor than competing products. For example, components of the illumination device proposed herein may be mounted to a breadboard of about 25 x 25 cm2and transported separately from the higher-cost illumination sources that may be mounted upon arrival. In one embodiment, the illumination device described herein may be produced as a plug-in to existing scanning optical (e.g., confocal) microscopes, which are the go-to imaging instrument option for researchers in life science due to their high signal-to-noise in 3D samples. The illumination device proposed herein may allow to upgrade existing scanning optical microscopy systems into super-resolution microscopes by replacing the external light path. The illumination device may also allow for reverting to regular operation of a scanning optical microscope with no physical changes being required, thus allowing to retain all existing capabilities of a microscope.

[0084] The following discussion provides many example embodiments. Although each embodiment represents a single combination of inventive elements, other examples may include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, other remaining combinations of A, B, C, or D, may also be used.

[0085] The term “connected” or "coupled to" may include both direct connection or coupling (in which two elements that are connected or coupled to each other contact each other) and indirect connection or coupling (in which at least one additional element is located between the two elements).

[0086] As can be understood, the examples described above and illustrated are intended to be exemplary only. The scope is indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An illumination device comprising: one or more light sources, each light source configured to generate a beam of light; one or more single-mode fibers, each single-mode fiber having a first end coupled to a respective one of the one or more light sources and a second end opposite the first end; and a photonic lantern having one or more single-mode input ports and a multimode output port, each single-mode input port connected to the second end of a respective one of the one or more single-mode fibers, the photonic lantern configured to receive, via the one or more single-mode fibers, one or more single-mode light inputs each having one propagation mode associated therewith, to combine the one or more single-mode light inputs into one light output having one or more higher order propagation modes associated therewith, and to provide, via the multimode output port, the light output to an imaging setup for illumination of a sample under examination.

2. The illumination device of claim 1 , further comprising one or more fiber connectors connecting the one or more light sources to the photonic lantern via the one or more singlemode fibers.

3. The illumination device of claim 2, further comprising one or more polarization controllers coupled to a respective one of the one or more fiber connectors, each polarization controller configured to alter a polarization of light transmitted in the respective one of the one or more single-mode fibers connected to the respective one of the one or more fiber connectors.

4. The illumination device of any one of claims 1 to 3, further comprising a few-mode fiber connected between the multimode output port of the photonic lantern and the imaging setup, wherein the photonic lantern is configured to provide the light output via the multimode output port for propagation in the few-mode fiber towards the imaging setup.

5. The illumination device of any one of claims 1 to 3, wherein the photonic lantern is configured to provide the light output via the multimode output port for propagation in free space towards the imaging setup.

6. The illumination device of any one of claims 1 to 5, wherein the light output is provided to the imaging setup for illumination of the sample comprising one or more fluorophores,further wherein a position of the light output relative to the sample is modulated to track the one or more fluorophores.

7. The illumination device of any one of claims 1 to 5, wherein the one or more light sources comprise a first laser operating at a first wavelength and two second lasers each operating at a second wavelength different from the first wavelength, each of the first wavelength and the second wavelength being in one of the visible spectrum, the infrared spectrum, and / or the ultraviolet spectrum.

8. The illumination device of claim 7, wherein the first laser is configured to generate a fluorescence excitation beam, and the two second lasers are configured to generate a STimulated Emission Depletion (STED) beam.

9. The illumination device of any one of claims 1 to 5, wherein the one or more light sources comprise a laser configured to generate a fluorescence excitation beam, and the one or more single-mode fibers comprise a first single-mode fiber and a second single-mode fiber, further comprising a beam splitter connected to the laser, the first single-mode fiber, and the second single-mode fiber, the beam splitter configured to split the excitation beam into a transmitted beam guided through the first single-mode fiber and a reflected beam guided through the second single-mode fiber.

10. The illumination device of any one of claims 1 to 9, wherein backscattered light and / or fluorescent light emitted from the sample in response to the illumination thereof is guided through the photonic lantern and through the one or more single-mode fibers.11 . The illumination device of claim 10, further comprising one or more light detectors and one or more circulators, each light detector coupled to a respective one of the one or more single-mode fibers via a respective circulator, the one or more light detectors configured to detect the backscattered light and / or the fluorescent light.

12. The illumination device of claim 11 , wherein the one or more light detectors are further configured to one of spectrally and spatially filter the backscattered light and / or the fluorescent light.

13. The illumination device of any one of claims 1 to 12, wherein the photonic lantern is configured to combine the one or more single-mode light inputs into the light output having one or more linearly polarized (LP) propagation modes associated therewith.

14. The illumination device of claim 13, wherein the photonic lantern is configured to combine the one or more single-mode light inputs into the light output having at least one of a fundamental LP mode and one or more higher order LP modes associated therewith.

15. The illumination device of any one of claims 1 to 14, wherein the photonic lantern is configured to combine the one or more single-mode light inputs into the light output having associated therewith at least two orthogonal propagation modes having unequal power levels.

16. The illumination device of claim 15, further comprising at least one polarizing controller configured to adjust the power level associated with at least one of the at least two propagation modes.

17. The illumination device of any one of claims 1 to 16, wherein the photonic lantern is configured to provide the light output to the imaging setup comprising a microscope.

18. The illumination device of claim 17, wherein the photonic lantern is configured to provide the light output to the imaging setup comprising a super-resolution microscope.

19. The illumination device of any one of claims 1 to 18, wherein the photonic lantern is a mode selective photonic lantern (MSPL).

20. The illumination device of any one of claims 1 to 19, wherein each light source has an input power, a polarization, and a wavelength associated therewith, further wherein the one or more light sources are connected at an input thereof to a controller configured to provide a control signal to each light source for adjusting at least one of the input power, the polarization, and the wavelength to control an intensity distribution of the light output.21 . The illumination device of any one of claims 1 to 20, wherein the light output is provided to the imaging setup for illumination of the sample comprising one or more fluorophores, the light output being used to manipulate a photophysical state of the one or more fluorophores in the sample.

Images