Fluoroscopy systems with rapid filter exchange

Abstract

Excitation and emission filters can be arranged on different platforms, such as two distinct filter wheels. In this way, any permutation of excitation and emission filters can be used in combination with one another. Filters can be arranged in a filter wheel using a combination of magnetic and mechanical features that provide quick replacement while maintaining alignment and positioning precision.

Description

[0001] FLUOROSCOPY SYSTEMS WITH RAPID FILTER EXCHANGE

[0002] Cross-Reference To Related Applications

[0003] This application is being filed as a PCT International application and claims the benefit of and priority to U.S. Provisional Application Nos. 63 / 677,847, filed July 31, 2024, and 63 / 707,977, filed October 16, 2024, the disclosures of which are incorporated herein by reference in their entirety.

[0004] Background

[0005] Optical filter cube exchange systems are utilized in various scientific and industrial applications to achieve precise control over light wavelengths and filtering. These systems allow for the rapid exchange of filters within an unchanged optical beam path, enabling users to adapt their setups for different imaging or data acquisition requirements.

[0006] One common application of filter cube exchange systems is in the screening of fluorescently labeled samples. By automatically switching between different filter sets and imaging channels, these systems enhance throughput and efficiency, enabling quick analysis of one or more samples that contain a variety of fluorophores. Additionally, in confocal microscopy, filter cube exchange systems play a role in selecting specific excitation and emission wavelengths. This selection helps reduce or eliminate out-of- focus light, resulting in clear and high-resolution images. An example of a filter cube exchange system is shown and described in the co-pending application US 63 / 677,847, filed on 31 July 2024, the contents of which are incorporated herein by reference in their entirety.

[0007] In any given fluoroscopy system, there may be a need for a variety of filter cubes that have various combinations of excitation and emission filters. The excitation filter is tuned to the excitation source (e.g., and incoming laser beam) and removes all but a desired wavelength or set of wavelengths that are routed to the sample. The emission filter is likewise tuned to the emitted light that emanates from the sample, and may be tuned to particular fluorophores or autofluorescent emissions. To provide the desired variety of excitation and emission filter combinations, a filter wheel as described in US 63 / 677,847 may have a relatively large number of filter cubes installed. However, due to space constraints within the equipment, the number of filter cubes on the wheel may necessarily be fewer than the quantity of different excitation and emission filter combinations that are desired. Therefore filter cubes are typically removable and replaceable so that the wheel can be re-loaded with different filter cubes during analysis, or between analysis of different samples, for example.

[0008] Summary

[0009] According to a first embodiment, a system for rapid filter exchange is described. The system includes an excitation light source arranged to produce an excitation light beam along an optical path towards a detector. The system further includes excitation filters arranged on a first platform, the first platform movable to position any selected one of the plurality of excitation filters within the optical path between the excitation light source and a sample holder. Emission filters are arranged on a second platform, the second platform movable to position any selected one of the plurality of emission filters within the optical path and opposite the sample holder from the excitation light source.

[0010] The platform and the second platform can be independently movable to position any permutation of the selected one of the excitation filters with any selected one of the emission filters. The first platform can include dichroic elements, each of the dichroic elements corresponding to one of the plurality of excitation filters. The optical path can include an unfiltered light portion that extends from the excitation light source to selected one of the plurality of excitation filters, an excitation light portion that extends from the selected one of the plurality of excitation filters to the sample holder, an unfiltered emission light portion that extends from the sample holder to the selected one of the plurality of emission filters, and a filtered emission light portion that extends from the selected one of the plurality of emission filters to the detector. The system can include sample arranged on the optical path at the sample holder. The second platform can include pockets and a magnet arranged to attract each one of the emission filters into a corresponding pockets. Alternatively, the second platform can include a magnet corresponding to each of the pockets, the magnets each arranged to attract a corresponding one of the emission filters into the corresponding pocket. The system can include other optical components arranged along the optical path. The optical path can be non-linear. Either or both of the first platform and the second platform can be a filter wheel. The emission filters can each have an optical filter arranged in a housing. Each of the pockets can define three stops arranged along a perimeter thereof corresponding to an installed position of the plurality of emission filters in each of the plurality of pockets. The housing of each of the emission filters can include a housing magnet. The system can also include a light trap arranged adjacent the plurality of emission filters. The first platform can include a machined engagement surface for each of the dichroic elements, the reflective surface of each dichroic element substantially in-plane with a corresponding one of the plurality of machined engagement surfaces.

[0011] According to a second embodiment, a method for rapid filter exchange is disclosed. The method includes generating an excitation light beam at an excitation light source, the excitation light beam extending along an optical path from the excitation light source towards a detector. The method further includes applying a selected excitation filter from a plurality of excitation filters to the excitation light beam to form a filtered excitation light beam, the plurality of excitation filters arranged on a first platform. The method includes interacting the filtered excitation light beam with a sample, collecting light emitted from the sample in response to interaction with the filtered excitation light beam as emission light, and applying a selected emission filter from a plurality of emission filters to the emission light to form filtered emission light, the plurality of emission filters arranged on a second platform. The method includes detecting a characteristic of the filtered emission light at the detector.

[0012] The method can further include independently moving the first platform and the second platform to position any permutation of the selected excitation filter with the selected emission filter. The first platform can include dichroic elements, each of which corresponds to one of the excitation filters. The optical path can include an unfiltered light portion, an excitation light portion, an unfiltered emission light portion, and a filtered emission light portion. The method can also include arranging a sample on the optical path at a sample holder. The second platform can include attracting the emission filters into pockets defined in the sample holder at a set of corresponding pockets. The second platform can include pockets and magnets corresponding to each one of the pockets and arranged to attract a corresponding emission filter into the corresponding pocket. The method can further include arranging optical components along the optical path. The optical path may be non-linear. At least one of the first platform and the second platform can be a filter wheel. Each of the plurality of emission filters can include an optical filter arranged in a housing. Each pocket can define three stops arranged along a perimeter of each pocket, corresponding to an installed position of each of the emission filters in each pocket. The housing of each of the excitation filters can include a housing magnet. The first platform can define machined engagement surfaces, each of the plurality of dichroic elements having a reflective surface that is substantially in-plane with a corresponding one of the machined engagement surfaces.

[0013] Brief Description of the Figures

[0014] Aspects and advantages of the embodiments provided herein are described with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, reference numbers may be re-used to indicate correspondence between referenced elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure.

[0015] FIG. 1 is a schematic view of an optical pathway extending from an excitation light source to a detector according to an embodiment.

[0016] FIG. 2 is a detailed partial view of the system of FIG. 1 , showing the first platform for excitation filtering in more detail.

[0017] FIG. 3 A is a detailed partial view of the system of FIG. 1, showing the light trap thereof.

[0018] FIGS. 3B and 3C are partial views of the system of FIG. 1, showing the alignment of the dichroic with a machined engagement surface of the first platform.

[0019] FIG. 4 is a detailed partial view of the system of FIG. 1, showing the second platform for emission filtering in more detail.

[0020] FIG. 5 is a detailed partial view of the system of FIG. 1 , showing an installed position of an emission filter in a pocket of the second platform shown in FIG. 4.

[0021] FIG. 6 is an exploded partial view of an emission filter and a corresponding magnet of the second platform of FIG. 4.

[0022] FIG. 7 is a detailed partial view of a portion of the second platform, in particular showing the perimeter of a single pocket thereof.

[0023] FIG. 8 is a method flowchart for a method of using the system of FIGS. 1-7. While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims.

[0024] Detailed Description

[0025] In microscopes it is advantageous to have the capability to exchange optical elements in order to produce the desired image qualities. Many microscopes incorporate epi filter cubes (also referred to herein simply as “filter cubes”) which may include optical components such as dichroic mirrors and other types of filters or optical elements to modify the propagated light. In sophisticated or automated microscopes multiple filter cubes may be used to address different imaging requirements. These filter cubes must be aligned accurately and repeatably to maintain image positioning and quality. This is a challenge because of the number of mechanical components that must be assembled in order to produce the multiple filter cubes and the exchange mechanism.

[0026] Filter cubes contain two types of filters. The first, excitation filters, are used to filter light from a light source to those which are useful in exciting the sample, such as to create fluorescence in the sample. The second, emission filters, are used to remove light reflected from the sample that is not of interest for detection. In one example, a particular wavelength band may be used to cause a fluorophore to fluoresce in a different wavelength band. In this example, the excitation filter may be used to pass only the light that causes fluorescence in the sample. The emission filter may block those same wavelengths that are transmitted by the excitation filter. The emission filter may, however, transmit the wavelengths of the fluoresced emission from the sample.

[0027] The combination of excitation and emission filters is therefore specific to characteristics of the light source, as well as the sample, or even for particular fluorophores in the sample. Accordingly, multiple filter cubes may be used and exchanged during analysis of a sample or set of samples. Changing between filter cubes takes time, and ensuring that the filter cube is appropriately selected and aligned in the optical pathway from the light source to the sample and then to the detector creates technical challenges. Systems and methods are described herein for rapid filter exchange in fluoroscopy. The system includes an excitation light source that produces an excitation light beam along an optical path towards a detector. A first platform can be provided with a plurality of excitation filters that can be positioned within the optical path between the excitation light source and a sample holder. Similarly, a second platform can be equipped with a plurality of emission filters that can be positioned within the optical path opposite the sample holder.

[0028] The excitation light beam can be filtered by applying a selected excitation filter from the first platform, resulting in a filtered excitation beam. This filtered excitation beam then interacts with a sample, causing the emission of light. The emitted light is collected and further filtered by applying a selected emission filter from the second platform, forming filtered emission light. Finally, a detector detects a characteristic of the filtered emission light.

[0029] The first platform and the second platform can be independently moved to position any combination of excitation and emission filters. The first platform also includes dichroic elements that correspond to the excitation filters. The optical path includes unfiltered light portions, excitation light portions, unfiltered emission light portions, and filtered emission light portions. The system may also include a sample arranged on the optical path at the sample holder and optical components along the optical path. At least one of the platforms can be a filter wheel, and the emission filters may be housed in magnetic pockets on the second platform.

[0030] The method for rapid filter exchange involves generating an excitation light beam, applying a selected excitation filter to the beam, and interacting the filtered excitation beam with a sample. The emitted light is then collected and filtered using a selected emission filter. The system allows for independent movement of the first and second platforms to achieve any desired combination of excitation and emission filters. The method also encompasses the use of dichroic elements on the first platform, arranging a sample on the optical path, and the inclusion of optical components. The method can be performed with a non-linear optical path and with at least one filter wheel platform.

[0031] In addition to the rapid filter exchange capabilities, the disclosed system and method use magnetic components for efficient filter handling. The second platform, which holds the emission filters, is equipped with magnets that attract and securely hold the filters in corresponding pockets. This magnetic arrangement ensures precise and reliable positioning of the emission filters within the optical path. Similarly, the housing of each emission filter includes a housing magnet, further enhancing the stability and ease of filter installation. By incorporating magnetic elements, the invention streamlines the filter exchange process, minimizing the risk of misalignment or displacement, and enabling rapid and accurate adjustments for optimal fluoroscopy imaging.

[0032] As shown and described with respect to the drawings herein, the excitation filters and the emission filters are arranged on separate platforms or filter wheels. In this way, any permutation of excitation and emission filters can be used by manipulating either or both of the platforms.

[0033] FIG. 1 shows an example of a system for rapid filter exchange 100. System 100 includes an excitation light source 102, a detector 104, a plurality of excitation filters 106, a first platform 108, a sample holder 110 holding a sample 112, a plurality of emission filters 114, a second platform 116, and a plurality of dichroic elements 118.

[0034] Excitation light source 102 can be, for example, a laser, an LED, a lamp (e.g., xenon, mercury, or halogen lamp), a globar, or any of a variety of narrowband or broadband light sources. In some embodiments, excitation light source 102 can be collimated and coherent, though this is not required in all embodiments.

[0035] Detector 104 is a camera, photodiode, or other light-sensitive device that collects light from the excitation light source 102 that has interacted with the sample 112, a selected one of the plurality of excitation filters 106S, a selected one of the plurality of emission filters 114S, and any of a variety of optical components 128 (not shown) which can include lenses, mirrors, filters, or other similar devices that steer, focus, or modify the light.

[0036] Excitation filters 106 are arranged on the first platform 108. As shown in FIG. 1, first platform 108 is a turret that includes four excitation filters 106 mounted thereon. In alternative embodiments, platform 108 could be a linear array of excitation filters 106, or a filter wheel that includes a plurality of excitation filters 106, or any other structure that permits the positioning of a selected one of the plurality of excitation filters 106S within the optical path (indicated by arrows in FIG. 1).

[0037] Sample holder 110 is positioned along the optical path (shown by arrows) such that the sample 112 is also positioned along the optical path. Sample holder 110 is shown as a substrate for a reflective sample in FIG. 1, but it should be understood that in other embodiments there may be samples 112 that are tested in a transmission mode. In such embodiments, the sample holder 110 can include a window or aperture such that the optical pathway is routed through the sample rather than reflecting from it. In some embodiments, sample 112 may be transmissive and sample holder 110 may be a mirror or otherwise reflective in wavelengths of interest such that light that has interacted with the sample 112 is routed towards the detector 104.

[0038] A plurality of emission filters 114 are arranged on the second platform 116. Emission filters 114 are arranged along the optical pathway (indicated by arrows) to receive light that has interacted with the sample 112. Similar to the first platform 108 described above, the second platform 116 can be manipulated such that a selected one of the plurality of emission filters 114S is arranged along the optical pathway indicated by arrows. As shown in FIG. 1, second platform 116 is a filter wheel, though in alternative embodiments it could take the form of a linear array of emission filters, or any other shape.

[0039] Dichroic elements 118 are arranged on the first platform 108 in FIG. 1. Dichroic elements 118 are reflective in some wavelength ranges and transmissive in others. For example, dichroic elements 118 can be reflective to expected wavelengths of fluoresced light while being transmissive in wavelengths of incoming light from the excitation light source 102. In some embodiments, the plurality of dichroic elements 118 can be used as a filter of the light from the excitation light source 102. As shown in FIG. 1, light in the reflective bandwidth of the dichroic 118 is deflected towards the center of the first platform 108 rather than being transmitted towards the sample 112. Light traps can be used (as described in more detail with respect to FIG. 3, below) to prevent such reflected light from arriving at detector 104.

[0040] As shown by the optical path indicated with arrows in FIG. 1, light passes from the excitation light source 102 to the detector 104 through a variety of intervening structures. Unfiltered light portion 120 is the portion of light emitted by the excitation light source 102 that has not been filtered or interacted with any other optical element or component. Unfiltered light portion 120 passes through a selected one of the plurality of excitation filters 106S and is reflected by one of the plurality of dichroics 118 toward the sample holder 110 and sample 112 at the first platform 108. The portion of the unfiltered light portion 120 that is reflected by the dichroic 118 after passing through the selected one of the plurality of excitation filters 106S is passed towards the sample 112 as excitation light portion 122. The portion of the unfiltered light portion 120 that is transmitted by dichroic 118 is received at a light trap (see FIG. 3A). A portion of the unfiltered light portion 120 may also be filtered by the selected one of the plurality of excitation filters 106S prior to arriving at the dichroic 118.

[0041] The excitation light portion 122 interacts with sample 112 on the sample holder 110, and is reflected back towards dichroic 118. Interaction with the sample 112 causes changes to the incoming excitation light portion 122. Specifically, excitation light portion 122 may be absorbed, reflected, or diffracted by the sample 112. In addition, sample 112 can also emit light in response to interaction with the excitation light portion 122. For example, sample 112 may be fluorescent at the wavelengths of the incoming excitation light portion 122. Alternatively or additionally, sample 112 may cause wavelength shift responses to the incoming excitation light portion 122, such as a Raman wavelength shift. In embodiments, the emitted light from sample 112 can have a wavelength that is lower than the incoming light of the excitation light portion 122 (such as in traditional fluorescence or Raman shifting responses). In other examples, sample 112 can produce a higher- wavelength emission than the incoming excitation light portion 122 (such as in a two-photon emission sample).

[0042] Light emanating from the sample 112 after interaction between the excitation light portion 122 and the sample 112 can include the reflected, refracted, transmitted, or wavelength-shifted excitation light portion 122, and can also include fluoresced or otherwise stimulated emitted light from the sample 112. This combined light that emanates from the sample 112 in response to the interaction between the sample 112 and the incoming excitation light portion 122 is referred to herein as the unfiltered emission light portion 124.

[0043] Unfiltered emission light portion 124 returns towards dichroic 118, as shown by the optical path indicated with arrows in FIG. 1. At dichroic 118, the unfiltered emission light portion 124 is at least partially transmitted towards the plurality of emission filters 114 arranged on the second platform 116. The unfiltered emission light portion 124 passes through a selected one of the plurality of emission filters 114S to become filtered emission light portion 126. It is this filtered emission light portion 126 that is received at the detector 104.

[0044] The optical path indicated with arrows therefore takes unfiltered light portion 120 from the excitation light source 102 and routes the light to a selected one of the plurality of excitation filters 106S, the dichroic 118, the sample 112, and the selected one of the plurality of emission filters 114S prior to interaction with the detector 104. This provides for selection of characteristics of the light at the time of interaction with the sample 112, as well as characteristics of the light at the time it interacts with the detector 104. Selecting a different one of the plurality of excitation filters 106 for use as the selected one of the plurality of excitation filters 106S can be accomplished by rotating the turret shown as the first platform 108 in FIG. 1. Likewise, selecting a different one of the plurality of emission filters 114 for use as the selected one of the plurality of emission filters 114S can be accomplished by rotating the filter wheel shown as the second platform 116 in FIG. 1.

[0045] By rotating the first platform 108 and the second platform 116, any permutation of selected filters (106S, 114S) can be used. That is, by using excitation and emission filters that are positioned on separate structures for selection, the limitation of filter cubes (in which one emission filter and one excitation filter are paired together) are overcome.

[0046] Additional optical components 128 can be used along the optical path indicated with the arrows in FIG. 1. Though these optical components 128 are not shown specifically in FIG. 1 , they will be readily understood by a person having ordinary skill in the art. For example, these optical components 128 can include lenses, filters, objectives, relays, mirrors, or the like. The position of the dichroic and excitation filters (106 and 118) can be positioned in the imaging path between the relay lenses where the light is not collimated rather than the last lens closer to the detector (104). This reduction of lenses that are in the excitation path can improve contrast by reducing background which could be generated from fluorescence and stray light in the system, for example Nipkow confocal microscope relay. The additional optical components 128 can be used to improve the efficiency of the system for rapid filter exchange 100 in some examples. For example, use of an objective at the sample 112, such as by mounting an objective at the sample holder 110, can be used to collect a greater portion of the emitted light that makes up the unfiltered emission light portion 124. Other optical components 128, such as mirrors or lenses, can be used to modify the optical path shown by arrows to be more space-efficient or follow a desired path for integration of the optical path into a larger optical system. Optical components 128 such as polarizing beam splitters, pinholes, 4f relays or the like could be implemented along the optical path indicated by arrows in order to interfere light and improve the signal-to-noise ratio of the filtered emission light portion 126 that arrives at the detector 104.

[0047] FIG. 2 is a detailed view of the first platform 108 of FIG. 1.

[0048] As described above, incoming unfiltered light portion 120 passes through a selected one of the plurality of excitation filters 106S and then is deflected by dichroic 118 to the sample 112 (indicated schematically as a box in FIG. 2) as excitation light portion 122. After interaction of excitation light portion 122 with the sample 112, the resulting unfiltered emission light portion 124 is returned through dichroic 118 and proceeds to the second platform (see FIG. 4).

[0049] In addition to the features previously described with respect to FIG. 1, FIG. 2 shows light traps 130. A light trap 130 is associated with each of the plurality of excitation filters 106. When a particular one of the plurality of excitation filters 106 is oriented along the optical path indicated with the arrows, light will pass through the selected one of the plurality of excitation filters 106S and then typically the filtered, excitation light portion 122 is directed in its entirety towards the sample 112 as shown in FIG. 2. However, it may be the case that some of the unfiltered light portion 120 is not absorbed by the selected one of the plurality of excitation filters 106S nor is it reflected by the dichroic 118. If such light is not handled, it may be received at the detector 104 or could cause other unwanted interference or optical artifacts or effects. Light traps 130 are therefore positioned to reduce the amount of unwanted light that does not follow the optical path indicated by the arrows in FIGS. 1 and 2.

[0050] In alternative embodiment, the emission excitation filter 106 may be omitted. For example, dichroic 118 may sufficiently filter for the wavelengths that are used for excitation of the sample. In such alternative embodiments, a different dichroic can optionally be used that is tuned to the light source 102 and / or the sample. An appropriately tuned dichroic that reflects the wavelengths that are emitted by the light source 102 and useful to excite fluorophores of interest in the sample 112, as well as being transmissive in the wavelengths of interest for light emitted by the sample, can therefore accomplish the same outcome as a paired dichroic 118 and selected one of the plurality of excitation filters 106S that are shown in FIG. 2.

[0051] FIG. 3 A is a detailed partial view of the first platform 108, showing one of the plurality of excitation filters 106 with its corresponding dichroic 118 and light trap 130. Additionally, FIG. 3 A shows excitation filter coupling magnet 132. Excitation filter coupling magnet 132 can be used for mounting the plurality of excitation filters 106 to the first platform 108. As described in the co-pending application US 63 / 677,847, magnetic mounting has advantages over conventional mechanical fastening. In addition to the reduction of optical errors that is described in that reference, magnetic attachments are fast and simple to remove and replace, such as to remove and replace individual ones of the plurality of excitation filters 106. Removal and replacement of individual ones of the plurality of excitation filters 106 can be accomplished either between uses of the system for rapid filter exchange 100, or even during use (such as when a different one of the plurality of excitation filters 106 is in use as the selected one of the plurality of excitation filters 106S).

[0052] FIG. 3B shows an arrangement of the dichroic 118 relative to a machined engagement surface 109 of the first platform 108. Machined engagement surface 109 can be formed to a high level of tolerance, and have all portions thereof substantially inplane. Machined engagement surface 109 is shown at a 45 degree angle from the axis of rotation of the first platform 108, consistent with the right angles of the optical path shown in FIG. 2. However, in other embodiments the angle of the machined engagement surface 109 relative to the remainder of the first platform 108 can be modified to deflect light from dichroic 118 in any desired direction.

[0053] Dichroic 118 is mounted against machined engagement surface 109, as described in more detail with respect to FIG. 3C, with the reflective surface thereof facing downwards (i.e., towards the sample in the light path depicted by arrows in FIG. 2). Pads 111 are arranged outside of the optical path and have a level of elasticity to act as compliant members to compress dichroic 118 against machined engagement surface 109 when pushed upon, as described in FIG. 3C.

[0054] Although machining is a typical and efficient manner to form machined engagement surface 109, it should be understood that in other embodiments the machined engagement surface 109 could be replaced by any other surface that is substantially flat, formed either by subtractive or additive processes.

[0055] FIG. 3C shows the structure of FIG. 3B, as well as a faceplate 113 that holds the dichroic 118 against the machined engagement surface 109 of the first platform 108. Faceplate 113 includes flange 115 that extends across both the machined engagement surface 109 and the dichroic 118, such that the dichroic is held substantially in-plane and parallel to the machined engagement surface 109. FIG. 3C also shows that faceplate 113 retains excitation filter coupling magnet 132, which is retained by corresponding magnet 133 of the first platform 108. Magnets 133 and 132 are arranged to be offset which produces a strong radial and normal alignment force. The magnetic retention is strong enough to resist the centripetal force caused by rotation of the first platform 108.

[0056] FIG. 4 shows the second platform 116, in this case a filter wheel. The plurality of emission filters 114 are arranged in a circle about the outer perimeter of the second platform 116. Second platform 116 is rotatable such that a selected one of the plurality of emission filters 114S is positioned in an expected optical path, as described above with respect to FIGS. 1 and 2.

[0057] FIG. 5 is a detailed view of one of the plurality of emission filters 114 in the second platform 116. The second platform 116 includes a plurality of pockets 134, which is more visible in this detailed view, each extending around a corresponding one of the plurality of emission filters 114. The plurality of pockets 134 are recessed into the second platform 116 and shaped to receive the plurality of emission filters 114.

[0058] As also shown in FIG. 5, each of the plurality of emission filters 114 includes a housing magnet 136. Housing magnet 136 is arranged on or within a housing 138 that also holds an optical filter 140. As described above, the optical filter 140 may be an emission filter.

[0059] Housing magnet 136 can be used to hold the plurality of emission filters 114 in their corresponding ones of the plurality of pockets 134. In some embodiments, there may be a plurality of magnets in the second housing 116, with a corresponding magnet located in the second platform 116 for each of the housing magnets 136, whereas in other embodiments the second platform 116 may be made of a magnetically susceptible material such that the housing magnet 136 causes an attraction inwards in the filter wheel that makes up the second platform 116. In still further embodiments there may be a single magnet located in the second platform 116 that attracts any or all housing magnets 136 for whichever plurality of emission filters 114 are inserted into any of the plurality of pockets 134. The magnets are offset to create both an attractive force normal to the housing 138 and the second platform 116 and an attractive force parallel to the housing 138 which draws the housing 138 into the pocket 134.

[0060] FIG. 5 further depicts stops 142. Stops 142 are provided to define the orientation and position of the plurality of emission filters 114 within their corresponding pockets 134, referred to herein as the installed position 500. Installed position 500 is the furthest inward that any of the plurality of emission filters 114 can be positioned in its corresponding one of the plurality of pockets 134. It has been found that two stops 142 in any given pocket 134 would permit rotation of the plurality of emission filters 114 within their corresponding ones of the plurality of pockets 134. Four stops 142 could result in the emission filters 114 being caught against only three stops 142 and not being pulled forward entirely into the corresponding pocket 134. By using three stops 142, the housing magnet 136 can pull the housing 138 into a well-defined installed position 500.

[0061] FIG. 6 is a partial view of the system for rapid filter exchange 100 depicting only one of the plurality of emission filters 114, including the housing 138, its corresponding optical filter 140, and its housing magnet 136. Second platform 116 is cut away from the partial view in FIG. 6 except for magnet 144, which is embedded in the second platform 116. Magnet 144 is arranged to attract its counterpart, housing magnet 136, and draw the housing 138 forward into the installed position (500, FIG. 5). The magnets 136 and 144 are arranged to be offset which produces a strong radial and normal alignment force. The magnetic retention is strong enough to resist or counteract the effect of the centripetal force caused by rotation of the platform.

[0062] FIG. 7 shows one of the plurality of pockets 134 that are defined in the second platform 116. Each of the plurality of pockets 134 defines a perimeter 146 that is substantially shaped as a larger version of the housing 138 of the plurality of emission filters 114. However, perimeter 146 also includes three stops 142, described above with respect to FIG. 5. Magnet 144 is embedded within the second platform 116 in the embodiment shown in FIG. 7. In alternative embodiments, magnet 144 could be arranged in an accessible region, such as on the surface of the platform 116 at the pocket 134 that it corresponds to.

[0063] FIG. 7 also shows how, when in the installed position 500 of FIG. 5, the optical filter 140 of the plurality of emission filters 114 will be aligned with an aperture defined in the second platform 116.

[0064] In sum, the magnets (136, 144) hold the plurality of emission filters 114 in the installed position and flat against the bottom of the pocket 134, while the stops 142 provide for correct orientation and alignment of the optical filter 140 with the aperture defined by the second platform 116. By holding the optical filter 140 substantially in alignment, diffraction and occlusion of the optical path is reduced or avoided. As used throughout this specification and the claims, “substantially” aligned or “substantially” in plane refers to a system that is nominally designed to maintain these components aligned or in-plane with one another, even if they may vary in some instances. A substantially in-plane system is one in which the contribution to locational or rotational errors that is caused by the out-of-plane condition is negligible.

[0065] The magnetic coupling and alignment and positioning improvements described herein provides users with an improved ability to change filter sets in filter cube systems without incurring optical alignment errors common to other implementations. Additionally, the excitation and emission filters in these systems are all independently changeable and permutable with one another, which reduces the need for a large number of filter cubes and time for changes therebetween during use of the system 100.

[0066] FIG. 8 is a method 800 for using a system such as the system for rapid filter change 100 described with respect to FIGS. 1-7.

[0067] According to method 800, at 802 a permutation of excitation and emission filters is selected. Selection of the permutation of excitation and emission filters can be based upon a sample that is being tested, or a particular fluorophore or other emission source of interest in a sample. To select the permutation of excitation and emission filters, a first platform (such as a turret or a filter wheel) that holds a plurality of excitation filters can be manipulated to arrange a selected one of the plurality of excitation filters in an optical pathway. Likewise, a second platform (such as a turret or a filter wheel) that holds a plurality of emission filters can be manipulated to arrange a selected one of the plurality of emission filters in the optical pathway.

[0068] At 804, the method 800 further includes generating an excitation beam. The excitation beam can be, for example, a laser beam or a collimated or focused beam of light from some other light source as described above. The excitation light beam can extend along an optical path from the excitation light source towards a detector, with various optical components arranged in the path therebetween.

[0069] At 806, the selected excitation filter is applied to the beam of light generated at 802. Applying the excitation filter at 806 can result in the generation of an excitation light portion from an unfiltered light portion.

[0070] At 808, the excitation light portion interacts with a sample. As described above, this interaction can result in emission by the sample, such as of fluoresced light, polarized light, phase-shifted light, or wavelength-shifted light (e.g. from two-photon emission, Raman shifted emissions, or stimulated fluorescent emissions). At 810, the emission light from the sample is collected. In some embodiments, the light may be collected at an objective, or by a focusing lens or mirror. The collected emission light can be routed towards an emission filter.

[0071] At 812, an emission filter is applied to the emission light. Similarly to the excitation filter, the emission filters can be arranged on a turret or filter wheel that can be manipulated to select an appropriate one of a plurality of emission filters. Applying the selected emission filter from the plurality of emission filters to the emission light at 812 forms filtered emission light.

[0072] At 814, a characteristic of the filtered emission light is detected at a detector. The characteristic can be simple (e.g., the existence or absence of light). For example, where the emission filter is a band-pass filter that only transmits light from a particular type of fluorescence, the presence of light at the detector may be sufficient to determine that that particular fluorophore is present in a sample. In other embodiments, more complex characteristics can be determined, including intensity, timing, wavelength, phase, polarity, wide-field or spatially-resolved images corresponding to the sample that indicate the presence or absence of a particular feature in different portions of the sample, or the like.

[0073] In embodiments, a dichroic may be used as well as the excitation and emission filters at 806 and 812 to transmit or reflect desired portions of light. In one embodiment, the first platform comprises a plurality of dichroic elements, each corresponding to one of the plurality of excitation filters.

[0074] This disclosure described some examples of the present technology with reference to the accompanying drawings, in which only some of the possible examples were shown. Other aspects can, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein. Rather, these examples were provided so that this disclosure was thorough and complete and fully conveyed the scope of the possible examples to those skilled in the art.

[0075] Although specific examples were described herein, the scope of the technology is not limited to those specific examples. One skilled in the art will recognize other examples or improvements that are within the scope of the present technology. Therefore, the specific structure, acts, or media are disclosed only as illustrative examples. Examples according to the technology may also combine elements or components of those that are disclosed in general but not expressly exemplified in combination, unless otherwise stated herein. The scope of the technology is defined by the following claims and any equivalents therein.

[0076] ASPECTS

[0077] Aspect 1. A system for rapid filter exchange, the system comprising: an excitation light source arranged to produce an excitation light beam along an optical path towards a detector; a plurality of excitation filters arranged on a first platform, the first platform movable to position any selected one of the plurality of excitation filters within the optical path between the excitation light source and a sample holder; and a plurality of emission filters arranged on a second platform, the second platform movable to position any selected one of the plurality of emission filters within the optical path and opposite the sample holder from the excitation light source.

[0078] Aspect 2. The system for rapid filter exchange of aspect 1, wherein the first platform and the second platform are independently movable to position any permutation of the selected one of the plurality of excitation filters with any selected one of the plurality of emission filters.

[0079] Aspect 3. The system for rapid filter exchange of any preceding aspect, wherein the first platform further comprises a plurality of dichroic elements, each of the plurality of dichroic elements corresponding to one of the plurality of excitation filters.

[0080] Aspect 4. The system for rapid filter exchange of aspect 3, wherein the optical path includes: an unfiltered light portion that extends from the excitation light source to selected one of the plurality of excitation filters, an excitation light portion that extends from the selected one of the plurality of excitation filters to the sample holder, an unfiltered emission light portion that extends from the sample holder to the selected one of the plurality of emission filters, and a filtered emission light portion that extends from the selected one of the plurality of emission filters to the detector.

[0081] Aspect 5. The system for rapid filter exchange of any preceding aspect, further comprising a sample arranged on the optical path at the sample holder.

[0082] Aspect 6. The system for rapid filter exchange of any preceding aspect, the second platform defining a plurality of pockets, the second platform further comprising a magnet arranged to attract one of the plurality of emission filters into a corresponding one of the plurality of pockets.

[0083] Aspect 7. The system for rapid filter exchange of any of aspects 1-5, the second platform defining a plurality of pockets, the second platform further comprising a plurality of magnets each corresponding to one of the plurality of pockets, the plurality of magnets each arranged to attract a corresponding one of the plurality of emission filters into the corresponding one of the plurality of pockets.

[0084] Aspect 8. The system for rapid filter exchange of any preceding aspect, further comprising optical components arranged along the optical path.

[0085] Aspect 9. The system for rapid filter exchange of aspect 8, wherein the optical path is non-linear.

[0086] Aspect 10. The system for rapid filter exchange of any preceding aspect, wherein at least one of the first platform and the second platform is a filter wheel.

[0087] Aspect 11. The system for rapid filter exchange either of aspects 6 or 7, wherein the plurality of emission filters each comprise an optical filter arranged in a housing.

[0088] Aspect 12. The system for rapid filter exchange of aspect 6 or 7, wherein each of the plurality of pockets defines three stops arranged along a perimeter of each of the plurality of pockets, corresponding to an installed position of the plurality of emission filters in each of the plurality of pockets.

[0089] Aspect 13. The system for rapid filter exchange of aspect 11 or 12, wherein the housing of each of the plurality of emission filters includes a housing magnet.

[0090] Aspect 14. The system for rapid filter exchange of any preceding aspect, further comprising a light trap arranged adjacent the plurality of emission filters.

[0091] Aspect 15. The system for rapid filter exchange of any of aspects 3-14, wherein the first platform defines a plurality of machined engagement surfaces, each of the plurality of dichroic elements having a reflective surface that is substantially in-plane with a corresponding one of the plurality of machined engagement surfaces.

[0092] Aspect 16. A method for rapid filter exchange, comprising: generating an excitation light beam at an excitation light source, the excitation light beam extending along an optical path from the excitation light source towards a detector; applying a selected excitation filter from a plurality of excitation filters to the excitation light beam to form a filtered excitation light beam, the plurality of excitation filters arranged on a first platform, interacting the filtered excitation light beam with a sample; collecting light emitted from the sample in response to interaction with the filtered excitation light beam as emission light; applying a selected emission filter from a plurality of emission filters to the emission light to form filtered emission light, the plurality of emission filters arranged on a second platform; and detecting a characteristic of the filtered emission light at the detector.

[0093] Aspect 17. The method of aspect 16, further comprising independently moving the first platform and the second platform to position any permutation of the selected excitation filter with the selected emission filter.

[0094] Aspect 18. The method of aspect 16 or 17, wherein the first platform comprises a plurality of dichroic elements, each corresponding to one of the plurality of excitation filters.

[0095] Aspect 19. The method of any of aspects 16-18, wherein the optical path includes an unfiltered light portion, an excitation light portion, an unfiltered emission light portion, and a filtered emission light portion.

[0096] Aspect 20. The method of any of aspects 16-19, further comprising arranging a sample on the optical path at a sample holder.

[0097] Aspect 21. The method of any of aspects 16-20, wherein the second platform defines a plurality of pockets and comprises a magnet arranged to attract one of the plurality of emission filters into a corresponding one of the plurality of pockets.

[0098] Aspect 22. The method of any of aspects 16-20, wherein the second platform defines a plurality of pockets and comprises a plurality of magnets, each of the plurality of magnets corresponding to one of the plurality of pockets and arranged to attract a corresponding emission filter into the corresponding one of the plurality of pockets.

[0099] Aspect 23. The method of any of aspects 16-22, further comprising arranging optical components along the optical path.

[0100] Aspect 24. The method of aspect 23, wherein the optical path is non-linear.

[0101] Aspect 25. The method of any of aspects 16-24, wherein at least one of the first platform and the second platform is a filter wheel. Aspect 26. The method of any of aspects 21 or 22, wherein each of the plurality of emission filters comprises an optical filter arranged in a housing.

[0102] Aspect 27. The method of aspect 26, wherein each pocket defines three stops arranged along a perimeter of each pocket, corresponding to an installed position of each of the plurality of emission filters in each pocket.

[0103] Aspect 28. The method of aspect 26 or 27, wherein the housing of each of the plurality of excitation filters includes a housing magnet.

[0104] Aspect 29. The method of any of aspects 18-28, wherein the first platform defines a plurality of machined engagement surfaces, each of the plurality of dichroic elements having a reflective surface that is substantially in-plane with a corresponding one of the plurality of machined engagement surfaces.

Claims

1. ClaimsWhat is claimed is:

1. A system for rapid filter exchange, the system comprising: an excitation light source arranged to produce an excitation light beam along an optical path towards a detector; a plurality of excitation filters arranged on a first platform, the first platform movable to position any selected one of the plurality of excitation filters within the optical path between the excitation light source and a sample holder; and a plurality of emission filters arranged on a second platform, the second platform movable to position any selected one of the plurality of emission filters within the optical path and opposite the sample holder from the excitation light source.

2. The system for rapid filter exchange of claim 1 , wherein the first platform and the second platform are independently movable to position any permutation of the selected one of the plurality of excitation filters with any selected one of the plurality of emission filters.

3. The system for rapid filter exchange of any preceding claim, wherein the first platform further comprises a plurality of dichroic elements, each of the plurality of dichroic elements corresponding to one of the plurality of excitation filters.

4. The system for rapid filter exchange of claim 3, wherein the optical path includes: an unfiltered light portion that extends from the excitation light source to selected one of the plurality of excitation filters, an excitation light portion that extends from the selected one of the plurality of excitation filters to the sample holder,an unfiltered emission light portion that extends from the sample holder to the selected one of the plurality of emission filters, and a filtered emission light portion that extends from the selected one of the plurality of emission filters to the detector.

5. The system for rapid filter exchange of any preceding claim, further comprising a sample arranged on the optical path at the sample holder.

6. The system for rapid filter exchange of any preceding claim, the second platform defining a plurality of pockets, the second platform further comprising a magnet arranged to attract one of the plurality of emission filters into a corresponding one of the plurality of pockets.

7. The system for rapid filter exchange of any of claims 1-5, the second platform defining a plurality of pockets, the second platform further comprising a plurality of magnets each corresponding to one of the plurality of pockets, the plurality of magnets each arranged to attract a corresponding one of the plurality of emission filters into the corresponding one of the plurality of pockets.

8. The system for rapid filter exchange of any preceding claim, further comprising optical components arranged along the optical path.

9. The system for rapid filter exchange of claim 8, wherein the optical path is nonlinear.

10. The system for rapid filter exchange of any preceding claim, wherein at least one of the first platform and the second platform is a filter wheel.

11. The system for rapid filter exchange either of claims 6 or 7, wherein the plurality of emission filters each comprise an optical filter arranged in a housing.

12. The system for rapid filter exchange of claim 6 or 7, wherein each of the plurality of pockets defines three stops arranged along a perimeter of each of theplurality of pockets, corresponding to an installed position of the plurality of emission filters in each of the plurality of pockets.

13. The system for rapid filter exchange of claim 11 or 12, wherein the housing of each of the plurality of emission filters includes a housing magnet.

14. The system for rapid filter exchange of any preceding claim, further comprising a light trap arranged adjacent the plurality of emission filters.

15. The system for rapid filter exchange of any of claims 3-14, wherein the first platform defines a plurality of machined engagement surfaces, each of the plurality of dichroic elements having a reflective surface that is substantially in-plane with a corresponding one of the plurality of machined engagement surfaces.

16. A method for rapid filter exchange, comprising: generating an excitation light beam at an excitation light source, the excitation light beam extending along an optical path from the excitation light source towards a detector; applying a selected excitation filter from a plurality of excitation filters to the excitation light beam to form a filtered excitation light beam, the plurality of excitation filters arranged on a first platform, interacting the filtered excitation light beam with a sample; collecting light emitted from the sample in response to interaction with the filtered excitation light beam as emission light; applying a selected emission filter from a plurality of emission filters to the emission light to form filtered emission light, the plurality of emission filters arranged on a second platform; and detecting a characteristic of the filtered emission light at the detector.

17. The method of claim 16, further comprising independently moving the first platform and the second platform to position any permutation of the selected excitation filter with the selected emission filter.

18. The method of claim 16 or 17, wherein the first platform comprises a plurality of dichroic elements, each corresponding to one of the plurality of excitation filters.

19. The method of any of claims 16-18, wherein the optical path includes an unfiltered light portion, an excitation light portion, an unfiltered emission light portion, and a filtered emission light portion.

20. The method of any of claims 16-19, farther comprising arranging a sample on the optical path at a sample holder.

21. The method of any of claims 16-20, wherein the second platform defines a plurality of pockets and comprises a magnet arranged to attract one of the plurality of emission filters into a corresponding one of the plurality of pockets.

22. The method of any of claims 16-20, wherein the second platform defines a plurality of pockets and comprises a plurality of magnets, each of the plurality of magnets corresponding to one of the plurality of pockets and arranged to attract a corresponding emission filter into the corresponding one of the plurality of pockets.

23. The method of any of claims 16-22, further comprising arranging optical components along the optical path.

24. The method of claim 23, wherein the optical path is non-linear.

25. The method of any of claims 16-24, wherein at least one of the first platform and the second platform is a filter wheel.

26. The method of any of claims 21 or 22, wherein each of the plurality of emission filters comprises an optical filter arranged in a housing.

27. The method of claim 26, wherein each pocket defines three stops arranged along a perimeter of each pocket, corresponding to an installed position of each of the plurality of emission filters in each pocket.

28. The method of claim 26 or 27, wherein the housing of each of the plurality of excitation filters includes a housing magnet.

29. The method of any of claims 18-28, wherein the first platform defines a plurality of machined engagement surfaces, each of the plurality of dichroic elements having a reflective surface that is substantially in-plane with a corresponding one of the plurality of machined engagement surfaces.

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