Rescanning optical system, microscope and method

Abstract

A rescan optical system is provided, which includes a scanning element and a first optical element that defines an incident illumination beam path leading to the scanning element for guiding a beam of illumination light onto the scanning element to provide a scanned illumination beam from the scanning element; a second optical element that defines a scanned sample optical path for guiding the scanned illumination beam from the scanning element towards the sample and illuminating the sample to generate sample light, and for guiding the captured sample beam onto the scanning element to provide a reverse-scanned sample beam from the scanning element; a third optical element that defines a reverse-scanned beam path for guiding at least a portion of the reverse-scanned sample beam from the scanning element back onto the scanning element to provide a reverse-scanned sample beam from the scanning element; and a fourth optical element that defines a rescan beam path for guiding the rescan sample beam towards the imaging plane of the imaging system.

Description

Technical Field

[0001] The present invention relates to a re-scanning optical system and method. Background Art

[0002] From De Luca GM, Breedijk RM, Brandt RA, et al., "Re-scan confocal microscopy: scanning twice for better resolution", Biomed Opt Express. 2013;4(11):2644–2656, published on October 25, 2013, doi:10.364 / BOE.4.002644, a re-scanning confocal microscope, hereinafter referred to as "De Luca", is known. This microscope has two units: 1) a standard confocal microscope with a set of scanning mirrors that have a dual function: scanning the excitation light and back-scanning the sample light, and 2) a re-scanning unit that "writes" the light passing through the pinhole to the camera. By controlling the ratio of the angular amplitudes of the respective scanning mirrors and the re-scanning mirror, the characteristics of the microscope can be controlled.

[0003] In such a re-scanning system, it is important that the scanning and re-scanning mirrors perform synchronous actions. Preferably, each scan of the scanning mirror starts and ends exactly at the start and end, respectively, of the corresponding scan of the re-scanning mirror. If the scanning and re-scanning mirrors move asynchronously, the obtained image will have a lower quality. As will be understood, at higher scanning speeds, the mirrors move faster, and the acceptable absolute error tolerance for synchronization becomes smaller. Since the degree of synchronization of the mirrors in DeLuca's system is limited, the scanning speed is also limited.

[0004] Similar systems are also described in B. Straub Benedikt et al., "Versatile high-speed confocal microscopy using a single laser beam", Rev. Sci. Instrum., 91, 033706 (2020); doi 10.1063 / 1.5122311, using two scanning elements (fx, fy) in each direction; G. Steinbach et al., "Fluorescence-detected linear dichroism imaging in a re-scan confocal microscope equipped with differential polarization attachment", European Biophysics Journal (2019) 48:457-463; doi 10.1007 / s00249-019-01365-4, which uses the system of De Luca (2013) mentioned above; G. M. R. DeLuca et al., "Configurations of the Re-scan Confocal Microscope (RCM) for biomedical applications", J. Microscopy 266(2) 2017.pp, 166-177 doi:10.1111 / jmi.12526; and WO2018 / 127566A1.

[0005] To overcome this synchronization problem, a single scanning mirror can be used to scan the excitation light, which is more commonly referred to as illumination light, or to rescan the fluorescence, which is more commonly referred to as sample light. For example, "Optical photon reassignment microscopy (OPRA)" by Roth et al., Optical Nanoscopy 2013 2:5, hereinafter referred to as "Roth", discloses an optical photon reassignment microscope. In this microscope, a laser emits excitation light at 488 nm, which is directed to a dichroic beam splitter that reflects the excitation light onto a scanning unit. The scanning unit scans the excitation light onto an objective lens, which focuses the excitation light onto the sample. The returned fluorescence is then directed back to the scanning unit and anti-scanned. Subsequently, the fluorescence is separated from the excitation light using the dichroic beam splitter. After this separation, the fluorescence beam passes through an adjustable detection pinhole that can be used to achieve confocal sectioning. The pinhole is located between two lenses that expand the fluorescence beam. After expansion, the fluorescence beam is rescaned using the same scanning system and projected onto a camera via a lens.

[0006] A disadvantage of this latter microscope setup is that since both the scanning and rescan use the same scanning system, the optical setup is rather large: the anti-scanned fluorescence beam is directed around the scanning system and then onto the scanning system that rescanes the fluorescence beam onto the camera.

[0007] WO 2020 / 263094 discloses a rescan microscope that relies on a rotatable element that includes at least two non-parallel reflective surfaces.

[0008] In view of the above, there is a need in the art for a more compact optical rescan system. SUMMARY OF THE INVENTION

[0009] In view of the above, a rescan optical system as described below is provided herein.

[0010] In one aspect, a rescan optical system includes a scanning element and a first optical element that defines an incident illumination beam path leading to the scanning element, the incident illumination beam path for directing a beam of illumination light onto the scanning element to provide a scanned illumination beam from the scanning element;

[0011] a second optical element that defines a scan beam path, the scan beam path for directing the scanned illumination beam from the scanning element towards the sample and illuminating the sample to produce sample light, and for directing a beam of captured sample light ("scanned sample beam") onto the scanning element to provide an anti-scanned sample beam from the scanning element;

[0012] A third optical element that defines a retroscan beam path for guiding at least a portion of a retroscanned sample beam from a scanning element back onto the scanning element to provide a rescan sample beam from the scanning element; and

[0013] A fourth optical element that defines a rescan beam path for guiding the rescan sample beam toward an imaging plane of an imaging system.

[0014] In this system, the third optical element defines a first beam path segment of the retroscan beam path that extends from the scanning element and a second beam path segment of the retroscan beam path that extends to the scanning element.

[0015] In addition, the fourth optical element defines a third path segment that extends from the scanning element between the first and second beam path segments and / or extends from the scanning element at a closed angle within a range of 80 - 100 degrees with respect to the scanned sample optical path.

[0016] Thus, the rescan optical system can be constructed to be compact. The retroscan beam path can define at least a portion of the size of the system. In addition, the system can be constructed with a relatively small number of optical elements, which can be of simple construction (mirrors, lenses, filters, etc.). Thus, the system is versatile.

[0017] The rescan optical system can be combined with an imaging system that defines and / or includes an imaging plane and / or with a microscope that holds a sample. The microscope can include an objective lens, and the scanning beam path and the scanned sample beam path can pass through the objective lens. The provided rescan optical system simplifies providing such a combination with a small footprint and / or in an arrangement where the rescan optical system can be selectively used or not used. This can be particularly applicable in the case of a fourth optical element that defines a third path segment that extends from the scanning element at a closed angle within a range of 80 - 100 degrees with respect to the scanned sample optical path, for example, at a substantially 90 - degree angle.

[0018] Optionally, the first and second path segments are each defined by a reflector, and there are no beam guiding optical elements for sample light between the reflector and the scanning element. The reflector can be a beam splitter for selectively reflecting a beam and / or a portion thereof, such as a dichroic mirror and / or a polarization - dependent reflector.

[0019] The one or more optical elements can be or include one or more of lenses, mirrors, beam splitters, filters, light guides, optical fibers, prisms, apertures, electro - optic modulators and / or acousto - optic modulators, polarizers, and / or any suitable combination thereof.

[0020] The scanning element can be a reflector defining a reflection side, in particular a mirror, preferably a dielectric mirror. In this case, the anti-scanning beam path and preferably the scanning sample optical path and / or the re-scanning beam path can be arranged on the reflection side, thus allowing for a small footprint of the system. The reflection side can be a half-space defined by the reflective surface of the scanning element, such as a mirror surface.

[0021] The provided re-scanning optical system can include a spatial filter in the anti-scanning beam path (DSc) to improve the image quality.

[0022] The third optical element can include an aperture and a lens or a lens system on both of its sides, each defining a focal point in the anti-scanning beam path. The focal points thus formed can overlap to form a common focal point, and the aperture can be arranged in the common focal point.

[0023] This is beneficial for the spatial filtering of the sample light and / or can simplify confocal microscopy.

[0024] Preferably, at least one of the scanning element and the lens or lens system, more preferably each of the lens and / or lens system, is separated along the anti-scanning beam path by the focal length of the corresponding lens or lens system. In a sense, the aperture and the scanning element can be considered to be on opposite sides of the lens or lens system.

[0025] This can avoid additional lenses or lens systems in the anti-scanning beam path, and / or increase the simplicity and / or robustness of the alignment of the third optical element, and possibly increase the simplicity and / or robustness of the alignment of the entire system and / or the system combined with another system.

[0026] The lens and / or lens system in the anti-scanning beam path can have the same focal length. This can simplify one or more of the design, manufacture, and alignment of the system. Similarly or alternatively, the manufacturing cost can be reduced since fewer different elements need to be provided.

[0027] In this system, the first optical element can include a lens or a lens system having a (first) focal length in the incident illumination beam, and a scanning element arranged along the illumination optical path at a distance of one (first) focal length from the lens or lens system.

[0028] Similarly or alternatively, the second optical element can include a lens or a lens system having a (second) focal length in the scanning beam path, and a scanning element arranged along the scanning beam path at a distance of one (second) focal length from the lens or lens system.

[0029] Alternatively or additionally, the fourth optical element may include a lens or lens system having a (fourth) focal length in the rescan beam path, and a scanning element arranged along the rescan beam path at a distance of one (fourth) focal length from the lens or lens system.

[0030] Any of these options, especially in combination, can improve the robustness of the optical system, especially with respect to alignment. Also, and in particular, this can help to provide one or more of the incident illumination beam path, the scan beam path, and the rescan beam path as a telecentric beam path, simplifying the combination of the rescan optical system with other optical systems. At least two of the first focal length, the second focal length, and the fourth focal length, preferably each of the focal lengths, may be equal.

[0031] Thus, in one aspect, there is also provided a rescan optical system, optionally incorporating any other embodiments discussed herein, including: a scanning element and a first optical element that defines an incident illumination beam path leading to the scanning element for guiding a beam of illumination light onto the scanning element to provide a scanned illumination beam from the scanning element; a second optical element that defines a scan beam path for guiding the scanned illumination beam from the scanning element towards the sample and illuminating the sample to generate sample light, and defines a scanned sample optical path for guiding the captured sample beam ("scanned sample beam") onto the scanning element to provide a backscanned sample beam from the scanning element; a third optical element that defines a backscanned beam path for guiding at least a portion of the backscanned sample beam from the scanning element back onto the scanning element to provide a backscanned sample beam from the scanning element; and a fourth optical element that defines a rescan beam path for guiding the rescan sample beam towards the imaging plane of the imaging system. This rescan optical system is also telecentric with respect to at least one of the scan beam path and the rescan beam path. Preferably, the system is doubly telecentric with respect to both the scan beam path and the rescan beam path. This can simplify the combination of the rescan optical system with other optical systems, especially considering the optical alignment of the various systems. Such additional optical systems may particularly include a microscope or microscope objective in or connected to the scan beam path and / or an imaging system in or connected to the rescan beam path.

[0032] The system may be configured to provide illumination light for illuminating the sample and generating a linear intensity distribution of sample light. Thus, a portion of the sample can be illuminated simultaneously. The rescan optical system may be configured such that the linear intensity distribution has a main extension direction perpendicular to the scanning direction of the illumination light at the sample, for illuminating the sample and causing the sample light to follow along the line. The main extension direction may be parallel to the rotation axis of the scanning element. Thus, by scanning the illumination light, the sample can be scanned by line scanning.

[0033] The first optical element may include incident light for defining a linear intensity distribution along the incident illumination beam path and / or one or more optical elements for providing light with a linear intensity distribution along the scanned illumination beam.

[0034] The incident illumination beam path may include one or more illumination point defining elements that define a linear intensity distribution. Specifically, the first optical element may include the one or more illumination point defining elements. The one or more illumination point defining elements may include lenses and / or beam masks; then, the lens may be or include, for example, a Powell lens and / or a cylindrical lens. Similarly or alternatively, the one or more excitation point defining elements may include one or more diffractive optical elements, such as diffraction gratings. The first optical element may include a lens or a lens system in the incident illumination beam having a (first) focal length. Then, the beam mask, if provided, may be arranged along the illumination optical path at a distance of one (first) focal length from the lens or lens system and in front of the lens or lens system. Similarly or alternatively, the scanning element may be arranged along the illumination optical path at a distance of one (first) focal length from the lens or lens system and behind the lens or lens system. Note that terms such as "in front" and "behind" refer to the direction of propagation of the light under discussion and / or the direction of propagation of the light associated with the optical element under discussion.

[0035] In the system, the scanned sample beam path, in particular the scanned illumination beam path and / or the scanned sample beam path, and the third beam path segment may define a closed angle in the range of 80 - 100 degrees, preferably in the range of 85 - 95 degrees, more preferably about 90 degrees. This can simplify the inclusion of the system in a microscope setup. For example, the system can be easily inserted into a right-angle beam line between a detection objective and an imaging system. In addition, this can simplify the arrangement of cables and / or other peripheral components and parts.

[0036] Note that here, the "closed angle" between two path segments refers to the minimum angle between the corresponding path segments with respect to the vertex of the path segments.

[0037] In the system, the incident illumination beam path and the scanned beam path may define a closed angle of less than 130 degrees, for example in the range of 100 - 125 degrees, preferably in the range of 105 - 120 degrees, more preferably in the range of 110 - 115 degrees.

[0038] The sample beam path and the first beam path segment may define a closed angle of less than 130 degrees, for example in the range of 100 - 125 degrees, preferably in the range of 105 - 120 degrees, more preferably in the range of 110 - 115 degrees.

[0039] The first beam path segment and the second beam path segment can define a closed angle that is less than 110 degrees, such as an acute angle and / or within the range of 80 - 100 degrees, preferably within the range of 85 - 95 degrees, and more preferably about 90 degrees.

[0040] The second beam path segment and the third beam path segment can define a closed angle of 90 degrees or an acute angle; this closed angle is preferably within the range of 90 - 50 degrees, preferably within the range of 80 - 60 degrees, and more preferably within the range of 75 - 65 degrees.

[0041] The scanning element can include a reflector that defines a normal, preferably a mirror, and more preferably a dielectric mirror, where each of the incident illumination beam path, the scanning beam path, the scanning sample beam, the anti - scanning beam path, and the rescan beam path is incident on the reflector at and / or is reflected by the reflector at respective angles with respect to the normal, where each of these respective angles with respect to the normal is less than 65 degrees, preferably less than 60 degrees, more preferably 55 degrees or less, and where each of these angles with respect to the normal is greater than 25 degrees, preferably greater than 30 degrees, such as 35 degrees or greater.

[0042] For a reflector, especially a mirror, such as a dielectric mirror, an incident angle close to or at an angle close to 45 degrees with respect to the normal of the reflective surface or reflective layer may be preferred compared to other incident angles. Thus, it is preferred that the various beam paths incident on the scanning element (and / or any other reflector in the system) and reflected by the scanning element are arranged at such an angle or close to such an angle.

[0043] Therefore, the arrangement of the optical elements and the alignment of the various beams can be arranged such that the closed angle between any of the previously discussed beams incident on the scanning element and reflected by the scanning element and the normal defined by the scanning element is less than 65 degrees, preferably less than 60 degrees, more preferably 55 degrees or less, and may also be greater than 25 degrees, preferably greater than 30 degrees, such as 35 degrees; thus, the beams are arranged within an angular spread of 20 degrees at an angle of 45 degrees with respect to the normal, preferably within an angular spread of 15 degrees, and more preferably within an angular spread of 10 degrees.

[0044] It should be noted that the smaller the angle between the incident beam on the mirror and the normal, the smaller the beam surface area on the mirror. Therefore, a smaller mirror may be sufficient to reflect most or all of the beam; reducing the size of the mirror can allow for a reduction in its inertia, which can enable a higher scanning speed.

[0045] The optical system can be combined with a microscope and / or can itself include an objective lens for focusing at least a portion of an illumination beam onto and / or into a sample. The objective lens can be an immersion objective lens for immersively focusing the at least a portion of the illumination beam onto and / or into the sample. The optical system can also include a sample holder for holding the sample, preferably for holding the sample at or near the focal point of the objective lens. Integrating the objective lens into the system can allow for an improvement in one or more of alignment, robustness, controllability, and image quality.

[0046] The optical system can be combined with an imaging system defining an image plane, and / or can itself include an imaging system that can define the image plane and can include a camera. In any case, the optical system can be configured to focus at least a portion of the rescan sample light onto the respective image planes. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above aspects will be explained in more detail with further details and benefits below with reference to the drawings showing, by way of example, a plurality of embodiments.

[0048] Figure 1 A first embodiment of the rescan optical system is shown;

[0049] Figure 2 A second embodiment of the rescan optical system is shown;

[0050] Figure 3 A third embodiment of the rescan optical system is shown. DETAILED DESCRIPTION

[0051] Note that the drawings are schematic, not necessarily drawn to scale, and details not necessary for understanding the invention may be omitted. Unless otherwise specified, terms such as "upward", "downward", "below", "above", etc. relate to the embodiments oriented in the drawings. In addition, elements that are at least substantially the same or perform at least substantially the same function are denoted by the same reference signs, distinguished by hundreds and / or by diacritical marks and / or letter suffixes where useful.

[0052] Furthermore, unless otherwise specified, terms such as "detachable" and "removably connected" are intended to mean that the respective components can be disconnected substantially without damaging or destroying any component, e.g., excluding structures where the components are integral (e.g., welded or molded together), but including structures where the components are connected by or as mating connectors, fasteners, releasable self-fastening features, etc. The verb "facilitate" is intended to mean "make easier and / or less complex", rather than "enable".

[0053] Figure 1Rescanning optical system 100 is schematically shown including optical elements 1-13, sample 14, optical elements 15-21, and camera 22 defining image plane 23. Optical elements 1-13 include scanning element 10. Most of the optical elements (here elements 1-11, 15-21) are enclosed in an optional light- and dust-tight housing 24. Scanning element 10 is rotatable, here about a rotation axis A perpendicular to the plane of the figure, i.e., the "scanning axis A" (see the curved double arrow); however, scanning element 10 can be rotated about another axis or about two perpendicular axes for scanning / anti-scanning / rescanning in other directions.

[0054] In system 100, illumination light from a light source (not shown, but typically including a laser light source) provided at the bold arrow travels along illumination optical path L in the order of reference numerals 1-14 via optical elements 1-13 to sample 14. Illumination optical path L includes incident illumination beam path IL and scanning beam path Sc. Some segments of illumination optical path L between consecutive optical elements among optical elements 1-13 are indicated alphabetically as a-f. The illumination light can be configured to excite fluorescence and / or one or more other luminescence processes in the sample rather than reflect and / or scatter the illumination light.

[0055] The first part of incident illumination beam path IL of illumination optical path L is defined by collimating lens 1, beam control mirror 2, illumination point defining lens 3 such as a Powell lens, focusing lens 4, and illumination point defining beam mask 5. Any of these elements is optional and can be used to direct the incident light (especially mirror 2) and / or to define a linear illumination point intensity pattern (lenses 1-4 and beam mask 5). The Powell lens (lens 3) tends to provide a more uniform intensity pattern along the main extension direction of the linear intensity distribution than a cylindrical lens for a Gaussian incident intensity distribution, yet provides a relatively higher intensity at the ends of the line. To improve the uniform illumination intensity over the intensity distribution, the intensity pattern of illumination point defining lens 3 can be focused on beam mask 5 by skimming the ends with beam mask 5. However, cylindrical lenses and / or more and / or other optical elements, such as diffractive elements, can also be used to define a suitable illumination point intensity pattern. Note that other illumination point intensity patterns, such as dot-shaped (e.g., Gaussian focus) or Bessel beam focus, and / or more complex illumination light intensity patterns can also be defined and used. The illumination light can be multi-color, but is preferably monochromatic.

[0056] Starting from the beam mask 5, the incident illumination beam path IL of the illumination optical path L reaches the reflective scanning element 10 via the first optical elements 6 - 9 along the segment a - e. In the illustrated embodiment, the first optical elements 6 - 9 sequentially include optional beam control mirrors 6 and 7, a lens 8, and a beam splitter 9. The beam splitter 9 can be one or more of a partial reflector, a polarization - dependent beam splitter, a wavelength - dependent beam splitter, and / or a wavelength - dependent reflector such as a dichroic mirror, especially a dichroic mirror, and the latter option may be preferred.

[0057] At the scanning element 10, the illumination light is reflected at the reflection angle γ+β+α as shown, and the illumination optical path L continues via the second optical elements 11, 12 that define the scanning beam path and via the objective 13 to the sample 14. In the illustrated embodiment, the second optical elements 11 and 12 are lenses. By rotating the scanning element 10 about the scanning axis A, the reflection angle γ+β+α at which the illumination beam leaves the scanning element 10 changes, and the illumination beam scans the sample 14 (see the straight double - arrow), illuminating the sample 14 at consecutive positions for generating sample light at these consecutive positions. The sample light can include one or more of the reflected illumination light and the light generated by and / or in the sample via any optical process such as fluorescence, phosphorescence, bioluminescence, multi - photon up - conversion, and / or down - conversion, etc. Thus, the illumination beam is directed onto the scanning element 10 to provide a scanning illumination beam from the scanning element 10 by reflection from the scanning element 10, and the scanning illumination beam is directed from the scanning element 10 towards the sample 14 for illuminating the sample 14 and generating sample light.

[0058] Preferably, the optical path L extends substantially in a plane preferably perpendicular to the scanning axis A for ease of alignment. Also, or alternatively, the linear intensity distribution of the illumination point intensity pattern is preferably aligned parallel to the scanning axis A at the scanning element 10.

[0059] In the system 100, the sample light from the sample 14 reaches the camera 22 along the sample optical path S via the optical elements 13 - 9 and 15 - 21 in the indicated order of the reference numerals 13 - 9, 15 - 21.

[0060] The sample optical path S includes a scanned sample optical path ScS, an anti - scanned beam path DSc, and a re - scanned beam path RSc that substantially coincide or overlap with the scanning beam path Sc here. Some segments of the sample optical path S are denoted as (in order) f, e, g - o.

[0061] Specifically, at least a part of the sample light is captured by the objective 13, thereby forming a scanned sample beam, and is directed onto the scanning element 10 via the second optical elements 12, 11, and the segment f.

[0062] At the scanning element 10, the sample light is reflected at the reflection angle α+β+γ as shown in the figure. By rotating the scanning element 10 about the scanning axis A, the reflection angle α+β+γ of the sample light leaving the scanning element 10 changes, the scanned sample light beam from the sample 14 (successive portions) is reverse-scanned, and a reverse-scanned sample light beam is provided from the scanning element 10. Starting from the scanning element 10, the sample optical path S continues through the third optical elements 9, 15 - 20, via sections e, g - m, and returns to the scanning element 10. The optical element 9 is a beam splitter that allows the sample light to pass through while it can block and / or reflect any illumination light reflected from the sample. Specifically, the sample light can have another wavelength and / or polarization direction different from the illumination light, and the beam splitter 9 can be a dichroic mirror or a filter and / or a polarization beam splitter.

[0063] In the illustrated embodiment, the third optical elements 15 - 20 sequentially include: a lens 15, a beam control mirror 16, an aperture 17, a beam control mirror 18, a lens 19, and a beam control mirror 20. Thus, a reverse-scanning beam path DSc is defined for guiding at least a portion of the reverse-scanned sample light beam from the scanning element 10 back to the scanning element 10 to provide a re-scanned sample light beam from the scanning element 10. Each of the lenses 15 and 19 defines a focus in the reverse-scanning beam path DSc, and these foci overlap to form a common focus, and the aperture 17 is arranged in the common focus. This can be used for spatial filtering and / or confocal sectioning. The aperture 17 can be a pinhole or a slit associated with the shape of the illumination point (here, a slit in terms of a linear illumination intensity distribution).

[0064] At the scanning element 10, the sample light is reflected at the reflection angle β as shown in the figure, and the sample optical path S continues along section n - o via the fourth optical element 21 and along the re-scanning beam path RSc towards the camera 22. By rotating the scanning element 10 about the scanning axis A, the reflection angle β of the reverse-scanned sample light leaving the scanning element 10 changes, and the re-scanned sample light beam from the scanning element 10 scans on the imaging plane 23 of the camera 22. Thus, the re-scanning beam path RSc is defined for guiding the re-scanned sample light beam towards the imaging plane 23 of the camera 22 of the imaging system.

[0065] Therefore, the incident illumination beam path IL and the reverse-scanning beam path DSc are static paths, while the scanning beam path Sc, the scanned sample optical path ScS, and the re-scanning beam path RSc are dynamic paths.

[0066] From Figure 1It can be clearly seen that the rescan beam path (section n) extends from the scanning element 10 between sections e and m of the reverse scan beam path. The rescan beam path (section o) crosses or intersects the reverse scan beam path (at section i). In particular, as shown, the rescan beam path RSc crosses or intersects the reverse scan beam path DSc, and there is no intervening reflector in the rescan beam path RSc between the scanning element 10 and the imaging system (camera 22). Preferably, one or more of the following options apply: the beam sections and their respective enclosed (reflected) angles α, β, and γ are arranged such that one or more of the following: the reflected angle β defined and enclosed by sections m and n is an acute angle; the angle α enclosed between sections f and m is approximately equal to the angle γ enclosed between sections e and n; the angle α + β enclosed between sections f and n is approximately equal to the angle γ + β enclosed between sections e and m; when the scanning element 10 rotates about the scan axis A, the angle α + β enclosed between sections f and n is approximately constant; the angle α + β enclosed between sections f and n is approximately 90 degrees. Specifically, the angles can be arranged such that angles α and γ are each approximately 15 - 30 degrees, e.g., 20 - 25 degrees, and angle β is approximately 55 - 75 degrees, e.g., 65 - 70 degrees.

[0067] Thus, with an angle α + β in the range of 80 - 100 degrees, preferably in the range of 85 - 95 degrees, and more preferably approximately 90 degrees, the scan beam path Sc and / or the scan sample optical path ScS, i.e., the optical path towards and / or from the sample 14, and the rescan beam path RSc towards the imaging system are at least approximately perpendicular at the scanning element.

[0068] The reflected angles δ, ε, ζ at the beam control mirrors 16, 18, 20 can be approximately perpendicular (the angle incident on each mirror and the angle emitted from each mirror are approximately 45 degrees with respect to the normal of each mirror). However, in the illustrated embodiment, these angles are slightly deviated to allow for a smaller device, while the various optical elements 4, 5, 9, 15, 17, 19, 21 do not interfere with the various beams; the lenses and mirrors can conform to a common optical size, e.g., having a diameter of 0.5 inches (12.7 mm), 20 mm, 25 mm, 1 inch (25.4 mm), 30 mm, 1.5 inches (38.1 mm), or even 50 mm or 2 inches (50.8 mm), and are mounted in optical mounts that should not or minimally intercept and / or obstruct the beam path segments to prevent signal loss.

[0069] In the illustrated embodiment, as an option, the lengths of the sections along each beam path are arranged such that:

[0070] Lens 4 projects the effective focus onto the mask 5;

[0071] a + b + c = d + e = focal length of lens 8;

[0072] f = focal length of lens 11;

[0073] e + g = h + i = focal length of lens 15, where g may include the effective optical length of beam splitter 9;

[0074] j + k = l + m = focal length of lens 19;

[0075] n = focal length of lens 21 = o (optionally).

[0076] Thus, if lenses 8, 11, 15, 19, and 21 are equal, the lengths of the respective segments can be arranged such that a + b + c = d + e = f = e + g = h + i = j + k = l + m = n = o (optionally), and a system is provided that provides a double telecentric system and does not provide intermediate magnification of the image.

[0077] Figure 2 A rescan optical system 200 of another embodiment is shown. For example, compared with Figure 1 the incident illumination beam path L is simplified, resulting in differently divided beam path segments g' and h', and the angles δ, ε, ζ between the beam segments are different. The microscope objective and the sample are not shown but are represented as microscope M. In system 200, the illumination light is optionally provided via optical fiber F, and the intensity distribution of the sample light used to illuminate the sample and caused by the sample can be defined by the exit lens and / or the end face of optical fiber F.

[0078] In this embodiment, as an option, the lengths of the segments along each beam path are arranged such that:

[0079] d’ + e = focal length of lens 208;

[0080] f = focal length of lens 211;

[0081] e + g’ + h’ = i = focal length of lens 215, where g’ may include the effective optical length of beam splitter 209;

[0082] j + k = l + m = focal length of lens 219;

[0083] n = focal length of lens 221 = o (optionally).

[0084] Thus, if lenses 208, 215, 219, and 221 have equal focal lengths, the lengths of the respective segments can be arranged such that d’ + e = f = e + g’ + h’ = i = j + k = l + m = n = o (optionally), providing a double telecentric system with a constant magnification.

[0085] Figure 3Shows a rescan optical system 300 of another embodiment. The incident illumination beam path L extends through a first optical element, here including a collimating lens 301, a beam control mirror 302, an illumination point defining lens 303, along segments d'' and d''' via the beam control mirror 306 to the beam splitter 309, and from there along segments e'-e''' via the optical element lenses 315 and the mirror 316 to the reflective scanning element 310. At the scanning element 310, the illumination light is reflected at the reflection angle γ+β+α as shown, and the illumination light path L continues along segment f via a second optical element, here including lenses 311 and 312, defining the scanning beam path Sc, and reaches the sample 314 via the objective lens 313 (possibly in a sample holder and / or with additional optical elements in between).

[0086] Light from the sample 314 travels along the sample optical path S, along the scanned sample optical path ScS, via the second optical elements 313 - 311 to the scanning element 310 (including segment f). The sample light further travels from the scanning element 310 along the reverse scanning beam path DSc via a third optical element, here including the first beam control mirror 316, the lens 315, the beam splitter 309 transmissive to the sample light, the beam control mirror 318, the aperture 317, the beam control mirror 320, the lens 319, along the sample light path S, and returns to the scanning element 310 (sequentially including segments e''', e'', e', g, i, j, k, and m). The optional lenses 315 and 319 disposed at the foci of the lenses 315 and 319 and the aperture 317 can be used for spatial filtering. Then, the sample light further travels from the scanning element 310 along the rescan optical path RSc via a fourth optical element, here including the lens 321 (sequentially including segments n and o) along the sample optical path S towards the imaging plane (23; 223; 323) of the imaging system, and the imaging system includes, for example, a camera 322 and an optional filter 324 here.

[0087] Compared with Figure 1 and Figure 2 the scanning beam path Sc and the scanned sample optical path ScS (segment f thereof) extend out from and extend to the scanning element 10 between segments e''' and m of the reverse scanning beam path, rather than on the rescan beam path RSc (segment n thereof). Now, the scanning beam path Sc and the scanned sample optical path ScS cross or intersect with the reverse scanning beam path (for example, at segment i or j, the latter case is shown). However, again as Figure 1 and Figure 2 shown, the scanned sample optical path (ScS) and the rescan beam path (RSc) extend substantially perpendicular to each other at the scanning element 10, defining a closed angle χ+ψ. The angle χ+ψ can be in the range of 80 - 100 degrees, preferably in the range of 85 - 95 degrees, more preferably about 90 degrees, as shown.

[0088] The second beam path segment m and the third beam path segment n define an enclosed angle that is an obtuse angle The first beam path segment e''' and the second beam path segment m define an enclosed angle χ+ψ that is less than 110 degrees, for example in the range of 80 - 100 degrees, preferably in the range of 85 - 95 degrees, and more preferably about 90 degrees.

[0089] Preferably, the lenses 308 and 315, 319 and 321 have equal focal lengths and are arranged relative to each other along the beam path appropriately, in particular separated by one or two times the focal length (d''+d'''+e' = e''+e''' = f = e'+g+i = j+k = m = n = focal length), such that Figure 3 the system is double telecentric.

[0090] The present disclosure is not limited to the above embodiments and can vary in many ways within the scope of the claims.

[0091] For example, the system can include more and / or differently arranged lenses and / or lens systems. Equally or alternatively, the static beam path can include more or fewer reflectors and / or be provided with one or more prisms.

[0092] Unless otherwise explicitly stated, the elements and aspects discussed with respect to a particular embodiment or in relation to a particular embodiment can be appropriately combined with the elements and solutions of other embodiments.

Claims

1. A rescan optical system (100; 200; 300) comprising a rotary scanning element (10; 210; 310) and one or more first optical elements (1-9; 201-209; 301-309) that define an incident illumination beam path (IL) leading to the scanning element (10; 210; 310), the incident illumination beam path (IL) for guiding a beam of illumination light onto the scanning element (10; 210; 310) to provide a scanned illumination beam from the scanning element (10; 210; 310) by rotating the scanning element (10; 210; 310); one or more second optical elements (11-12; 211-212; 311-312) that define a scan beam path (Sc) for guiding the scanned illumination beam from the scanning element (10; 210; 310) towards a sample (14; 214; 314) and illuminating the sample (14; 214; 314) to generate sample light, and that define a scanned sample optical path (ScS) for guiding a beam of captured sample light onto the scanning element (10; 210; 310) to provide a reverse-scanned sample beam from the scanning element (10; 210; 310) by rotating the scanning element (10; 210; 310); one or more third optical elements (15-20; 215-220; 315-320) that define a reverse-scan beam path (DSc) for guiding at least a portion of the reverse-scanned sample beam from the scanning element (10; 210; 310) back onto the scanning element (10; 210; 310) to provide a rescan sample beam from the scanning element (10; 210; 310) by rotating the scanning element (10; 210; 310); one or more fourth optical elements (21; 221; 321) that define a rescan beam path (RSc) for guiding the rescan sample beam towards an imaging plane (23; 223; 323) of an imaging system (22; 222; 322); wherein the one or more third optical elements (15-20; 215-220; 315-320) define a first beam path segment (e; e; e''') of the reverse-scan beam path (DSc) extending from the scanning element (10; 210; 310) and a second beam path segment (m; m; m) of the reverse-scan beam path (DSc) extending to the scanning element (10; 210; 310), and - the one or more fourth optical elements (21; 221; 321) define a third path segment (n; n; n) as part of the rescan beam path (RSc), the third path segment (n; n; n) · in the first beam path segment (e; e) and the second beam path segment (m; m) extending from and / or between the scanning element (10; 210; 310) · With respect to the scanning beam path (Sc) and / or the scanning sample optical path (ScS, f; The ScS, f; ScS, f) forms a closed angle within the range of 80 - 100 degrees extending from the scanning element (10; 210; 310); or - The one or more second optical elements (11 - 12; 211 - 212; 311 - 312) define a path segment (f) as part of the scanning beam path (Sc) and / or the scanning sample optical path (ScS), and the path segment (f) extends from the scanning element (10; 210; 310) between the first beam path segment (e''') and the second beam path segment (m) and / or extends to the scanning element (10; 210; 310); and / or where a) the scanning beam path (Sc) and / or the scanning sample optical path (ScS) and b) the rescan beam path (RSc) define a closed angle (α + β; χ + ψ) within the range of 80 - 100 degrees at the scanning element (10; 210; 310).

2. The rescan optical system (100; 200; 300) according to claim 1, wherein the rescan beam path (RSc) defines a closed angle (α + β; χ + ψ) within the range of 85 - 95 degrees at the scanning element (10; 210; 310).

3. The rescan optical system (100; 200; 300) according to claim 1, wherein the rescan beam path (RSc) defines a closed angle (α + β; χ + ψ) of 90 degrees at the scanning element (10; 210; 310).

4. The rescan optical system (100; 200; 300) according to claim 1, which includes a spatial filter in the anti - scan beam path (DSc).

5. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the one or more third optical elements (15 - 20; 215 - 220; 315 - 320) include apertures (17; 217; 317) and lenses (15, 19; 215, 219; 315, 319) or lens systems on both sides thereof, each defining a focus in the anti - scan beam path (DSc), wherein the foci overlap to form a common focus, and the aperture (17; 217; 317) is arranged in the common focus, and Among them, the scanning element (10; 210; 310) and each of the lenses (15, 19; 215, 219; 315, 319) or lens systems are separated along the anti - scan beam path (DSc) by the focal lengths of the respective lenses (15, 19; 215, 219; 315, 319) or lens systems.

6. The rescan optical system (100; 200; 300) according to claim 3, wherein the lenses (15, 19; 215, 219; 315, 319) and / or lens systems in the anti - scan beam path (DSc) have the same focal length.

7. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the one or more first optical elements (1-9; 201-209; 301-309) include a lens (8; 208; 308) or a lens system having a focal length in the incident illumination beam path (IL), and the scanning element (10; 210; 310) is arranged along the incident illumination beam path (IL) at a distance of one focal length from the lens (8; 208; 308) or the lens system, and / or the one or more second optical elements (11-12; 211-212; 311-312) include a lens (11; 211; 311) or a lens system having a focal length in the scanning beam path, and the scanning element (10; 210; 310) is arranged along the scanning beam path at a distance of one focal length from the lens (11; 211; 311) or the lens system, and / or the one or more fourth optical elements (21; 221; 321) include a lens (21; 221; 321) or a lens system having a focal length in the rescan beam path, and the scanning element (10; 210; 310) is arranged along the rescan beam path at a distance of one focal length from the lens (21; 221; 321) or the lens system.

8. The rescan optical system (100; 200; 300) according to the preceding claim 1 or 2, which includes a rotary scanning element (10; 210; 310) and one or more first optical elements (1-9; 201-209; 301-309) that define an incident illumination beam path (IL) leading to the scanning element (10; 210; 310), the incident illumination beam path (IL) being for guiding a beam of illumination light onto the scanning element (10; 210; 310) to provide a scanned illumination beam from the scanning element (10; 210; 310) by rotating the scanning element (10; 210; 310); one or more second optical elements (11-12; 211-212; 311-312) that define a scanned illumination beam path (Sc), the scanned illumination beam path (Sc) being for guiding the scanned illumination beam from the scanning element (10; 210; 310) towards the sample (14; 214; 314) and illuminating the sample (14; 214; 314) to generate sample light, and It defines a scanned sample optical path (ScS) for guiding a captured sample light beam ( " scanned sample light beam ” ) onto the scanning element (10; 210; 310) to provide a reverse scanned sample light beam from the scanning element (10; 210; 310) by rotating the scanning element (10; 210; 310). one or more third optical elements (15-20) that define a reverse scan beam path (DSc), the reverse scan beam path (DSc) being for guiding at least a portion of the reverse scan sample beam from the scanning element (10; 210; 310) back onto the scanning element (10; 210; 310) to provide a rescan sample beam from the scanning element by rotating the scanning element (10; 210; 310); One or more fourth optical elements (21; 221; 321) defining a rescan beam path (RSc) for directing the rescan sample beam towards the imaging plane (23; 223; 323) of the imaging system; wherein the rescan optical system is telecentric with respect to at least one of the scan beam path and the rescan beam path.

9. The rescan optical system (100; 200; 300) according to claim 8, wherein the rescan optical system is double telecentric with respect to both the scan beam path and the rescan beam path.

10. The rescan optical system (100; 200; 300) according to claim 1 or 2, configured to provide illumination light for illuminating the sample (14; 214; 314) and generating a linear intensity distribution of the sample light, wherein in particular the main extension direction of the linear intensity distribution is perpendicular to the direction of scanning the sample.

11. The rescan optical system (100; 200; 300) according to claim 10, wherein the incident illumination beam path (IL) is provided with one or more illumination point defining elements (3; 203; 303) defining the linear intensity distribution, Among them, in particular, the one or more first optical elements (1-9; 201-209; 301-309) include the one or more illumination point defining elements (3; 203; 303).

12. The rescan optical system (100; 200; 300) according to claim 11, wherein the one or more illumination point defining elements include a Pawell lens and / or a beam mask.

13. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the path segment (f) and the third path segment (n) define a closed angle (α + β) of less than 110 degrees.

14. The rescan optical system (100; 200; 300) according to claim 13, wherein the closed angle (α + β) is an acute angle and / or in the range of 80-100 degrees.

15. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the first beam path segment (e; e; e''') and the second beam path segment (m; m; m) define a closed angle (β + γ; ) that is less than 110 degrees.

16. The rescan optical system (100; 200) according to claim 1 or 2, wherein the second beam path segment (m) and the third path segment (n) define a closed angle of 90 degrees or an acute angle.

17. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the scanning element (10; 210; 310) includes a reflector defining a normal, wherein each of the incident illumination beam path (IL), the scan beam path (Sc), the scan sample optical path (ScS), the reverse scan beam path (DSc) and the rescan beam path (RSc) is incident on the reflector at respective angles with respect to the normal and / or is reflected by the reflector at respective angles with respect to the normal, wherein the respective angles with respect to the normal are less than 65 degrees, and wherein the respective angles with respect to the normal are greater than 25 degrees.

18. The rescan optical system (100; 200; 300) according to claim 17, wherein the reflector comprises a mirror and / or a dielectric mirror.

19. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the optical system (100) comprises an objective lens (13; 213; 313) for focusing at least a part of the illumination beam onto the sample (14) and / or into the sample (14).

20. The rescan optical system (100; 200; 300) according to claim 1 or 2, wherein the optical system (100) comprises an imaging system (22; 222; 322) defining the imaging plane (23; 223; 323), and the optical system (100; 200; 300) is configured to focus at least a part of the rescan sample light onto the imaging plane (23; 223; 323).

Images