Cover glass thickness compensation by tube lens arrangement

Abstract

The microscope imaging system includes an objective lens (18) configured to collect light from the biological sample to form a magnified image of the biological sample (S). The microscope imaging system also includes a camera (14) including an imaging sensor. The imaging sensor is configured to detect the magnified image of the biological sample. The microscope imaging system further includes a tube lens (16) disposed between the objective lens and the camera. The tube lens is configured to project the magnified image of the biological sample onto the imaging sensor of the camera. The tube lens is spaced from the imaging sensor of the camera by a distance (D2) that is less than a focal length of the tube lens.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a PCT International Application and claims the benefit of priority from U.S. Provisional Patent Application No. 63 / 321,996, entitled "Cover Glass Thickness Correction By Tube Lens Placement," filed March 21, 2022, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] Various types of testing related to the diagnosis and treatment of a patient may be performed by analysis of a patient sample. This may include analysis of the patient's microorganism (or "microbe"), in addition to analysis of the sample to determine chemistry, antigens, antibodies, blood counts, particulates (e.g., sediments), and other factors that may affect the patient's health. A microorganism is a microscopic organism, such as a bacteria, fungus, or virus, and may be unicellular or multicellular. In analyzing a microorganism, a biological sample containing the patient's microorganism may be taken from the patient's infectious material, bodily fluids, or abscess, combined with various reagents, placed in a test panel or array, cultured, and analyzed to aid in the treatment of the patient. Analysis of the patient's chemistry, immunoassays, blood counts, particulates, and other characteristics may be performed as well. For these various analyses, automated biochemical analyzers or biological testing systems have been developed to meet the needs of medical facilities and other institutions to facilitate the analysis of patient samples and improve the accuracy and reliability of results when compared to analyses using manual operations, and to aid in the determination of the effectiveness of various antimicrobial agents.

[0003] A biological sample may be passed through a flow cell of a biological testing system for analysis. For example, such testing systems may include a microscopic imaging system that may include an imaging device, such as a high-speed, high-resolution camera, configured to capture an image of the biological sample (e.g., urine) as it passes through an analysis region of the flow cell. Such microscopic imaging systems typically include an optical element called an "objective lens" that collects light from the biological sample to form a magnified image of the sample, which may then be focused onto an imaging sensor of the camera at an image plane, for example via a tube lens.

[0004] The medium between the biological sample and the objective lens affects the manner in which light is focused onto the imaging plane and therefore the quality of the image acquired by the camera. Many readily available objective lenses are designed for imaging samples through standard microscope glass coverslips having a thickness of approximately 170 μm (e.g., 170 μm + / - 5 μm). For example, such objective lenses may be configured to correct for distortions that may otherwise be caused by the 170 μm layer of glass. However, the thickness of the walls of the flow cell may be thicker for some applications (e.g., approximately 1 mm), limiting the optical performance with objective lenses designed for standard coverslips. This thickness may be desirable to provide sufficient strength to the flow cell to facilitate reliable operation, and reducing the thickness of the flow cell walls to more closely approximate the thickness of a standard coverslip may be impractical. Therefore, specialized objective lenses may be used to maintain the optical performance required to facilitate high-precision imaging through the flow cell. For example, such specialized objectives may include cover glass thickness adjustment mechanisms, which undesirably add significant cost and limit the available product selection. Alternatively, such specialized objectives may be custom designed and optimized for a particular set of requirements, which also undesirably add significant cost. In other cases, additional optical elements for cover glass correction may be incorporated to mitigate degradation of image quality caused by cover glass thicknesses outside the design range, which undesirably increases the overall complexity of the optical system and also adds significant cost.

[0005] While this specification describes the invention in detail and concludes with claims which distinctly claim the same, it is believed the invention will be better understood from the following description of specific examples read in conjunction with the accompanying drawings, in which like reference numerals identify the same elements, and in which: [Brief description of the drawings]

[0006] [Figure 1]FIG. 1 is a schematic diagram of a biological analysis system including an exemplary microscope imaging system for imaging a sample through a coverslip. [Diagram 2] 2 is an image acquired by the microscope imaging system of FIG. 1 through the cover slip of FIG. 1. [Diagram 3] FIG. 1 is a schematic diagram of another biological analytical system including another exemplary microscope imaging system for imaging a sample through a flow cell wall. [Figure 4] 4 is a series of images acquired by the microscope imaging system of FIG. 3 through the flow cell wall of FIG. 3 with the tube lens of the microscope imaging system positioned at various distances from the camera of the microscope imaging system. [Diagram 5] FIG. 4 is a schematic diagram of the biological analysis system of FIG. 3 including an exemplary oblique illumination system. [Figure 6] 4 is a schematic diagram of another exemplary microscopic imaging system for use in the biological analysis system of FIG. 3. Summary of the Invention

[0007] The drawings are not intended to be limiting in any respect, and it is contemplated that the various embodiments of the invention may be embodied in a variety of other ways, including ways not necessarily depicted in the drawings. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the invention and, together with the description, serve to explain the principles of the invention. It is understood, however, that the invention is not limited to the precise configurations shown.

[0008] In some embodiments, a microscopic imaging system is described. The microscopic imaging system includes an objective lens configured to collect light from a biological sample to form a magnified image of the biological sample. The microscopic imaging system also includes a camera including an imaging sensor. The imaging sensor is configured to detect the magnified image of the biological sample. The microscopic imaging system further includes a tube lens disposed between the objective lens and the camera. The tube lens is configured to project the magnified image of the biological sample onto the imaging sensor of the camera. The tube lens is spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens. In some embodiments, the objective lens includes an infinity corrected objective lens. Additionally or alternatively, the objective lens may be optimized to collect light from the biological sample through a coverslip having a thickness of about 170 μm. The focal length of the tube lens may be between about 50 mm and about 250 mm. In some embodiments, the distance that the tube lens is spaced from the imaging sensor of the camera is less than about one-half the focal length of the tube lens. Additionally or alternatively, the tube lens may be fixed to prevent movement relative to the imaging sensor of the camera. The tube lens may be fixed to prevent movement relative to the objective lens. In some embodiments, the objective lens is fixed to prevent movement relative to the imaging sensor of the camera. Additionally or alternatively, the microscope imaging system may further include a lens housing, and the tube lens is housed within the lens housing. For example, the tube lens may be held within the lens housing by at least one retaining ring. Additionally or alternatively, the lens housing may include a first end configured to be coupled to the camera. The lens housing may also include a second end configured to be coupled to the objective lens. Additionally or alternatively, the lens housing may include first and second lens housing portions coupled to each other. The biological sample may be housed within the flow cell, and the objective lens may be configured to collect light from the biological sample through a flow cell wall of the flow cell.In some embodiments, a biological analysis system includes the above-described microscopic imaging system and a flow cell configured to receive a biological sample, the flow cell including a flow cell wall. The objective lens is configured to collect light from the biological sample through the flow cell wall. The flow cell wall may have a thickness between about 0.2 mm and about 2 mm.

[0009] In some embodiments, a biological analysis system is described. The biological analysis system includes a flow cell configured to accommodate a biological sample. The flow cell includes a flow cell wall having a thickness of about 1 mm. The biological analysis system also includes a microscope imaging system, the microscope imaging system includes an infinity corrected objective configured to collect light from the biological sample through the flow cell wall to form a magnified image of the biological sample. The microscope imaging system also includes a camera including an imaging sensor. The imaging sensor is configured to detect the magnified image of the biological sample. The microscope imaging system further includes a tube lens disposed between the infinity corrected objective and the camera. The tube lens is configured to project the magnified image of the biological sample onto the imaging sensor of the camera. The tube lens is spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens. In some embodiments, the infinity corrected objective is optimized to collect light from the biological sample through a cover slip having a thickness of about 170 μm. Additionally or alternatively, the focal length of the tube lens may be about 100 mm.

[0010] In some embodiments, a method of imaging a biological sample is described. The method includes collecting light from the biological sample through an objective lens and forming a magnified image of the biological sample through the objective lens. The method also includes projecting the magnified image of the biological sample onto an imaging sensor of the camera through a tube lens disposed between the objective lens and the camera. The tube lens is spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens. The method further includes detecting the magnified image of the sample through the imaging sensor of the camera. In some embodiments, the objective lens is optimized to collect light from the biological sample through a cover slip having a thickness of about 170 μm, and collecting light includes collecting light from the biological sample through a flow cell wall having a thickness of about 1 mm.

[0011] In some embodiments, a microscopic imaging system is described. The microscopic imaging system includes an objective lens configured to collect light from a biological sample to form a magnified image of the biological sample, the biological sample being contained within a flow cell. The microscopic imaging system also includes a camera with an imaging sensor, the imaging sensor configured to detect the magnified image of the biological sample. The microscopic imaging system further includes a tube lens disposed between the objective lens and the camera. The tube lens is configured to project the magnified image of the biological sample onto the imaging sensor of the camera, the tube lens being spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following description of a specific example of the present invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the present invention will become apparent to those skilled in the art from the following description. The following description is, by way of example, one of the best modes contemplated for carrying out the present invention. As will be appreciated, the present invention is capable of other distinct and obvious aspects, none of which deviates from the present invention. Thus, the drawings and description should be regarded as illustrative in nature, and not restrictive.

[0013] It will be appreciated that one or more of the teachings, expressions, versions, examples, etc. described herein may be combined with one or more of the other teachings, expressions, versions, examples, etc. described herein. Thus, the teachings, expressions, versions, examples, etc. described below should not be taken in isolation with respect to each other. Various suitable ways in which the teachings herein can be combined will be apparent to those skilled in the art in light of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0014] The terms "about," "approximately," and the like, as used herein in connection with any numerical value or range of values, are intended to encompass the exact value recited, as well as an appropriate tolerance that allows the recited feature or combination of features to function for the intended purpose described herein.

[0015] FIELD OF THE DISCLOSURE The present disclosure relates to devices, systems, compositions and methods for analyzing biological samples. An exemplary biological analysis system (10, 110) including an exemplary microscopic imaging system (12, 112, 212) is described in detail with reference to Figures 1-5.

[0016] A. First Exemplary Biological Analysis System Embodiment Including First Exemplary Microscopic Imaging System Embodiment 1 illustrates at least a portion of an exemplary biological analysis system (10), including, among other components, an exemplary microscopic imaging system (12). As illustrated, the microscopic imaging system (12) includes an imaging device in the form of a camera (14), a tube lens (16), and an objective lens (18). The tube lens (16) may be housed within a lens housing or lens tube (not shown), which may be coupled to each of the camera (14) and the objective lens (18) to secure each of the camera (14), the tube lens (16), and the objective lens (18) in a fixed position relative to one another.

[0017] The microscopic imaging system (12) is configured to image a biological sample, such as a urine sample (S), to aid in the analysis of the sample (S) by the biological analysis system (10). Although imaging of a urine sample (S) is illustrated and described herein, the microscopic imaging system (12) may image a variety of fluids, including, but not limited to, other bodily fluids, such as synovial fluid, blood, bone marrow, etc.

[0018] The objective lens (18) is configured to collect light from the sample (S) to form a magnified image of the sample (S). In the embodiment shown, the objective lens (18) is configured to collect light transmitted through a medium in the form of a glass cover slip (20) of the biological analysis system (10). More specifically, the cover slip (20) is of standard construction and has a thickness of approximately 170 μm. In this regard, the objective lens (18) may be configured to compensate for distortions that may otherwise be caused by the cover slip (20) when the cover slip is spaced from the objective lens (18) a predetermined working distance (W) such that the sample (S) is spaced from the objective lens (18) a distance (X) substantially equal to the sum of the working distance (W) and the thickness of the cover slip (20). For example, the objective lens (18) may include an optical train (not shown) configured to correct for image blurring that may otherwise be caused by the cover slip (20) when spaced apart from the objective lens (18) by the working distance (W). Additionally or alternatively, the thickness and material of the cover slip (20) may be considered as input parameters into the optical design of the objective lens (18), along with other parameters such as the wavelength of light and the required optical performance. It will be appreciated that the optical performance of the optical design is highly sensitive to the operating conditions and may degrade significantly for even small deviations from the optimal operating conditions. In this example, the objective lens (18) is designed to work optimally with a 170 μm thick glass cover slip (20) placed over the sample (S).

[0019] It will be appreciated that such optimization of the objective lens (18) for imaging through a cover slip (20) having a thickness of about 170 μm may render the objective lens (18) undesirable for imaging through a cover slip having a thickness significantly less than or significantly greater than about 170 μm and / or through other types of media, because the objective lens (18) may not be able to adequately correct for the distortions caused thereby, or may otherwise lead to degraded and / or suboptimal optical performance. Thus, the objective lens (18) may be specifically designed for imaging through a cover slip (20) having a thickness of about 170 μm, spaced apart from the objective lens (18) by a predetermined working distance (W). Additionally or alternatively, the objective lens (18) may be configured as an infinity corrected objective lens (also referred to as an "infinity back focal length objective lens"), such that light exiting the objective lens (18) may be focused to infinity. By way of example, the objective lens (18) may include a CFI Achromat LWD 20X 0.40NA objective lens sold by Nikon®, which has a working distance (W) of approximately 3.90 mm. It will be appreciated that any other suitable type of objective lens may be used, such as an objective lens with a similar magnification and similar working distance as the CFI Achromat LWD 20X 0.40NA objective lens sold by Nikon®.

[0020] The tube lens (16) is disposed between the objective lens (18) and the camera (14), and the tube lens (16) is configured to project a magnified image of the sample (S) onto an imaging sensor (not shown) of the camera (14). In some embodiments, the tube lens (16) may have a focal length between about 50 mm and about 250 mm, such as between about 100 mm and about 200 mm. For example, the tube lens (16) may have a focal length between about 80 mm and about 120 mm, or between about 90 mm and 110 mm. In one example, the tube lens (16) has a focal length of about 100 mm. In either case, the imaging sensor of the camera (14) is configured to detect an image of the sample (S) focused onto the image sensor by the tube lens (16) after being magnified by the objective lens (18). The camera (14) may be in operative communication with a processor (not shown) to facilitate transmission of signals to and from the processor. For example, such a processor may be configured to send command signals to the camera (14), such as to initiate the capture of one or more images by the camera (14), and / or to receive data signals from the camera (14) corresponding to the captured images.

[0021] As shown in FIG. 1, the tube lens (16) of the microscope imaging system (12) is spaced from the imaging sensor of the camera (14) by a first distance (D1) substantially equal to the focal length of the tube lens (16) such that the position of the imaging sensor of the camera (14) can be substantially coincident with the focal point of the tube lens (16). For example, if the tube lens has a focal length of about 100 mm, the first distance (D1) can be about 100 mm. Such an arrangement of the tube lens (16) relative to the imaging sensor of the camera (14) can define a nominal design configuration of the microscope imaging system (12) in which the objective lens (18) is optimized for use with a coverslip (20) having a thickness of about 170 μm. This is because the tube lens (16) can form a properly focused image of the sample (S) at the focal point of the tube lens (16) for acquisition by the imaging sensor of the camera (14). An example of such a properly focused image (I) acquired by the camera (14) is shown in FIG. 2. The image (I) shown in Figure 2 is of a resolution target pattern with 228 line pairs per millimeter imaged using the objective lens (18) with the microscope imaging system (12) in its nominal design configuration. It will be recognized that varying the distance between the tube lens (16) and the camera (14) from the nominal design configuration may degrade the quality of the image (I) acquired by the camera (14) through the coverslip (20).

[0022] B. Second Exemplary Biological Analysis System Embodiment Including a Second Exemplary Microscopic Imaging System Embodiment 3 illustrates at least a portion of another exemplary biological analysis system (110), including, among other components, another exemplary microscopic imaging system (112). The microscopic imaging system (112) is structurally and functionally similar to the microscopic imaging system (12) described above, except as described below as different. In this regard, the microscopic imaging system (112) includes the camera (14), tube lens (16), and objective lens (18) described above in connection with FIG. 1. The tube lens (16) may be housed within a lens housing or lens tube (not shown), which may be coupled to each of the camera (14) and objective lens (18) to secure each of the camera (14), tube lens (16), and objective lens (18) in a fixed position relative to each other.

[0023] As explained above, the objective lens (18) is optimized for imaging through a glass cover slip (20) having a thickness of about 170 μm. However, in the embodiment shown, the objective lens (18) is used to collect light from a sample (S) that has been transmitted through a medium in the form of a glass flow cell wall (120) of the biological analysis system (110), which acts like the glass cover slip (20) in terms of transmitting light. More specifically, the flow cell wall (120) has a thickness of between about 0.2 mm and about 2 mm, about 0.5 mm to about 1.5 mm, about 0.8 mm to about 1.2 mm, or about 1 mm. Increasing the thickness of the glass flow cell wall to something thicker than 170 μm (e.g., between about 0.2 mm and about 2 mm, or about 1 mm) can help increase the structural strength to handle system pressures and reduce or eliminate the possibility of glass breakage. Due to the significant increase in thickness of the flow cell wall (120) relative to the cover slip (20), the objective lens (18) may not be configured to compensate for distortions caused by the flow cell wall (120) or may not be expected to lead to reduced and / or suboptimal optical performance. Furthermore, the flow cell wall (120) may be spaced from the objective lens (18) by a distance less than the working distance (W) of the objective lens (18) to space the sample (S) from the objective lens (18) by the same distance (X) as described above in relation to FIG. 1. Thus, the sample (S) may be spaced from the objective lens (18) by a distance greater than the nominal working distance (W) of the objective lens (18). In some cases, the distance the sample (S) is spaced from the objective lens (18) may be determined using the following formula: X=W+D * (1-n1 / n2) Where: X is the distance that the sample (S) is separated from the objective lens (18). W is the working distance of the objective lens (18). D is the thickness of the flow cell wall (120). n1 is the refractive index of air. n2 is the refractive index of the flow cell wall (120) (eg, glass).

[0024] As a result, the objective lens (18) may be focused at a point significantly farther away than the specimen (S) because the greater thickness of the flow cell wall (120) relative to the coverslip (20) may cause the focal point to be shifted farther away from the objective lens (18). Rather than the objective lens (18) being specifically reconfigured to correct for distortions that might otherwise be caused by the flow cell wall (120) and / or its spacing relative to the objective lens (18), the spacing between the imaging sensor of the camera (14) and the tube lens (16) is adjusted away from the nominal design configuration shown in FIG. 1 to correct for such distortions.

[0025] In this regard, the tube lens (16) of the microscope imaging system (12) is spaced from the imaging sensor of the camera (14) by a second distance (D2) that is significantly smaller than the focal length of the tube lens (16) such that the position of the imaging sensor of the camera (14) can be between the focal point of the tube lens (16) and the tube lens (16) itself. For example, if the tube lens has a focal length of about 100 mm, the second distance (D2) can be significantly smaller than 100 mm. In some embodiments, the second distance (D2) can be approximately half the focal length of the tube lens (16). For example, if the tube lens has a focal length of about 100 mm, the second distance (D2) can be approximately 50 mm. In some embodiments, the second distance (D2) that the tube lens (16) of the microscope imaging system (12) is spaced from the imaging sensor of the camera (14) can be determined according to the table below.

[0026] [Table 1]

[0027] Such an arrangement of the tube lens (16) relative to the imaging sensor of the camera (14) may deviate significantly from the nominal design configuration of the microscope imaging system (12), in which the objective lens (18) is optimized for use with a cover slip (20) having a thickness of about 170 μm. However, this deviation can compensate for distortions caused by the increased thickness of the flow cell wall (120) relative to the cover slip (20), thereby allowing the imaging sensor of the camera (14) to acquire an image of improved quality compared to an image acquired through the flow cell wall (120) using the microscope imaging system (12) in the nominal design configuration of FIG. 1. Examples of such images (I1, I2, I3, I4, I5) acquired by the camera (14) with the tube lens (16) in various positions are shown in FIG. 4. The distances that the tube lens (16) is spaced from the imaging sensor of the camera (14) are shown in the table below.

[0028] [Table 2]

[0029] The images (I1, I2, I3, I4, I5) shown in Figure 4 are of a resolution target pattern with 228 line pairs per millimeter imaged using the objective lens (18) with the microscope imaging system (12) in a non-nominal design configuration. More specifically, the first image (I1) corresponds to the tube lens (16) being at or near the position shown in Figure 3, the fifth image (I5) corresponds to the tube lens (16) being in a position close to the position shown in Figure 1, and the second, third, and fourth images (I2, I3, I4) correspond to the tube lens (16) being in a position in between. As shown, reducing the distance between the tube lens (16) and the camera (14) compared to the nominal design configuration improves, rather than degrades, the quality of the images (I1, I2, I3, I4, I5) acquired by the camera (14) through the flow cell wall (120). More specifically, the illustrated images (I1, I2, I3, I4, I5) show that image contrast generally increases as the tube lens (16) is moved closer to the camera (14) from the nominal placement of the tube lens (16) in its nominal design configuration, with the quality of the first image (I1) acquired with the tube lens (16) positioned closest to the camera (14) being better than the quality of the fifth image (I5) acquired with the tube lens (16) positioned farthest from the camera (14) (e.g., at or near the nominal placement of the tube lens (16) in its nominal design configuration). In the example shown, the quality of the second image (I2) may be the most favorable (e.g., when the second distance (D2) is about 31.32 mm), with the quality of the first image (I1) degrading slightly compared to the quality of the second image (I2). In some embodiments, optimal image quality may be achieved when the second distance (D2) is between about one-quarter the focal length of the tube lens (16) and about one-half the focal length of the tube lens (16), such as about one-third the focal length of the tube lens (16).

[0030] In some embodiments, the spacing between the imaging sensor of the camera (14) and the tube lens (16) may be further adjusted away from the nominal design configuration to compensate for distortions that may be caused by a fluid film layer between the optically transmitted sample (S) and the flow cell wall (120). For example, such a fluid film layer may have a thickness of about 80 μm.

[0031] Thus, an objective lens (18) originally optimized for imaging through a coverslip (20) having a thickness of about 170 μm may be incorporated into a microscopic imaging system (112) and used to facilitate high-precision imaging of a sample (S) through a flow cell wall (120) having a thickness of about 1 mm, without specially reconfiguring the objective lens (18) itself or adding additional components, complexity, or cost compared to the microscopic imaging system (12). Although the microscopic imaging system (112) has been described with respect to imaging a sample (S) through a flow cell wall (120) having a thickness between about 0.2 mm and about 2 mm (e.g., about 1 mm) (and / or through a fluid membrane layer having a thickness of about 80 μm), it will be appreciated that the microscopic imaging system (112) may be used to image a sample (S) through any other type of medium. For example, the microscopic imaging system (112) may be used to image the sample (S) through a glass cover slip (not shown) having a thickness between about 0.2 mm and about 2 mm (e.g., about 1 mm). Additionally or alternatively, the microscopic imaging system (112) may be used to image the sample (S) through a dish (not shown) containing the sample (S) and having a thickness between about 0.2 mm and about 2 mm (e.g., about 1 mm).

[0032] 5 illustrates exemplary additional components of the biological analytical system (110). In the embodiment shown, the flow cell wall (120) described above is incorporated into a flow cell (121) that receives sample (S) and / or additional fluids (e.g., surrounding ambient fluids) from one or more conduits (122) of the biological analytical system (110) that are disposed upstream relative to the flow cell (121).

[0033] As shown, an oblique illumination system (124) is disposed on the opposite side of the flow cell (121) from the microscopic imaging system (112) along its optical axis to illuminate the sample (S) to facilitate capturing an image of the sample (S) by the microscopic imaging system (112). In the example shown, the oblique illumination system (124) includes a light emitter (125), a collection lens (126), an aperture mask (127), and a condenser lens (128). The light emitter (125) may be any suitable light source, including, for example, an arc lamp, a light emitting diode (LED), or any suitable light emitter for providing either pulsed or continuous illumination. The collection lens (126) may be any suitable collection lens that collects light emitted from the light emitter (125) and transmits the light uniformly onto the aperture mask (127). In this regard, the aperture mask (127) may be opaque and may block light from the collection lens (126) everywhere except through its decentered aperture (129), such that light transmitted through the aperture (129) reaches the condenser lens (128) decentered from the optical axis. The condenser lens (128) may be any suitable condenser lens that angles the light it receives toward the sample (S) such that the sample (S) is illuminated with light at an oblique angle.

[0034] C. Third Exemplary Microscopy Imaging System Embodiment 6 illustrates another exemplary microscopic imaging system (212) for use with a biological analysis system, such as biological analysis system (110). The microscopic imaging system (212) is structurally and functionally similar to the microscopic imaging system (112) described above, except as differentiating as described below. In this regard, the microscopic imaging system (212) includes a camera (214), a tube lens (216), and an objective lens length (L) similar to the objective lens (18) described above in connection with FIGS. 1 and 3. obj ) and a working distance (W). In some variations, the objective lens includes an objective lens (218) having an objective lens length (L obj ) may be approximately 2.212 inches. Additionally or alternatively, the working distance (W) may be approximately 0.154 inches. The tube lens (216) is housed within a lens housing or lens tube (230) that is coupled to the camera (214) at or near a first (e.g., proximal) end of the lens tube (230). The lens tube (230) is coupled to the objective lens (218) at or near a second (e.g., distal) end of the lens tube (230) to secure each of the camera (214), tube lens (216), and objective lens (218) in a fixed position relative to one another.

[0035] In the embodiment shown, the lens tube (230) includes a first (e.g., proximal) lens tube portion (230a) and a second (e.g., distal) lens tube portion (230b) coupled to one another. The tube lens (216) is housed within the first lens tube portion (230a) proximate to the camera (214) and has a tube lens effective length (L tube ) from the distal end of the second lens tube section (230b). In some variations, the tube lens effective length (L tube) may be approximately 4.049 inches. In either case, the tube lens (216) is spaced from the imaging sensor (not shown) of the camera (214) by a distance significantly less than the focal length of the tube lens (216), such that the location of the imaging sensor of the camera (214) can be between the focal point of the tube lens (216) and the tube lens (216) itself. In the example shown, the imaging sensor of the camera (214) is spaced from the imaging sensor (not shown) by a sensor offset (O sens ) from the flange or other mating surface of the camera (214) and from the tube lens (216) by a sensor distance (D sens ) apart. In some variations, such as when the focal length of the tube lens (216) is about 100 mm, the sensor distance (D sens ) may be approximately 1.233 inches. Additionally or alternatively, the sensor offset (O sens ) may be approximately 0.690 in. As shown, the tube lens (216) is fixedly held within the first lens tube section (230a) by a pair of lens retaining rings (232).

[0036] The second lens tube portion (230b) is configured to be coupled to the objective lens (218). In this regard, the second lens tube portion (230b) includes a coupling mechanism (234), such as a thread or a socket, configured to mate with a corresponding coupling mechanism of the objective lens (218) to couple the objective lens (218) to the second lens tube portion (230b). In some embodiments, the objective lens (218) is at least partially received within the second lens tube portion (230b). Additionally or alternatively, the objective lens (218) may at least partially extend away (e.g., distally) from the second lens tube portion (230b). In either case, the objective lens (218) may be optimized for imaging through a glass coverslip (20) having a thickness of about 170 μm, as described above. Nevertheless, due to the positioning of the tube lens (216) relative to the imaging sensor of the camera (214) in a manner similar to that described above in connection with FIG. 3, an objective lens (218) may be incorporated into the microscope imaging system (212) and used to facilitate high-precision imaging of the sample (S) through a flow cell wall (120) or glass cover slip / dish having a thickness of approximately 1 mm.

[0037] Different configurations of the components shown in the figures or described above, as well as components and steps not shown or described, are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Although embodiments of the invention have been described for purposes of illustration and not of limitation, alternative embodiments will become apparent to the reader of this patent. In certain cases, method steps or operations may be performed or executed in a different order, or operations may be added, deleted, or modified. It will be understood that in certain aspects of the invention, a single component may be replaced with multiple components, and multiple components may be replaced with a single component, to provide an element or structure or to perform a given function or functions. Except where such a substitution would not operate to implement a particular embodiment of the invention, such substitution is deemed to be within the scope of the invention. Thus, the invention is not limited to the embodiments described above or shown in the figures, and various embodiments and modifications may be made without departing from the scope of the following claims. [Explanation of symbols]

[0038] 12, 112, 212 Microscope Imaging System 10, 110 Biological analysis system 14,214 Camera 16, 216 tube lens 18, 218 Objective Lens 20 Coverslips S sample W Working distance X distance D1 First Distance D2 Second distance I, I1, I2, I3, I4, I5 images 120 Flow cell wall 124 Oblique Lighting System 125 Illuminant 126 Condenser Lens 127 Aperture Mask 128 Condenser Lens 129 Aperture 230 Lens Tube 230a 230b Lens tube part 232 Lens Retaining Ring

Claims

1. (a) an objective lens configured to collect light from a biological sample to form a magnified image of the biological sample; (b) a camera comprising an imaging sensor, the imaging sensor configured to detect the magnified image of the biological sample; and (c) a tube lens disposed between the objective lens and the camera, the tube lens configured to project the magnified image of the biological sample onto the imaging sensor of the camera, the tube lens being spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens; and A microscope imaging system comprising:

2. The microscope imaging system of claim 1 , wherein the objective lens comprises an infinity corrected objective lens.

3. 10. The microscope imaging system of claim 1, wherein the objective lens is optimized to collect the light from the biological sample through a coverslip having a thickness of about 170 μm.

4. 2. The microscope imaging system of claim 1, wherein the focal length of the tube lens is between about 50 mm and about 250 mm.

5. 2. The microscope imaging system of claim 1, wherein the distance that the tube lens is spaced from the imaging sensor of the camera is less than about half the focal length of the tube lens.

6. The microscope imaging system of claim 1 , wherein the tube lens is fixed to prevent movement relative to the imaging sensor of the camera.

7. The microscope imaging system of claim 1 , wherein the tube lens is fixed to prevent movement relative to the objective lens.

8. The microscope imaging system of claim 1 , wherein the objective lens is fixed to prevent movement relative to the imaging sensor of the camera.

9. 10. The microscope imaging system of claim 1, further comprising a lens housing, the tube lens being housed within the lens housing.

10. The microscope imaging system of claim 9 , wherein the tube lens is held in the lens housing by at least one retaining ring.

11. The microscope imaging system of claim 9 , wherein the lens housing includes a first end configured to be coupled to the camera.

12. The microscope imaging system of claim 11 , wherein the lens housing includes a second end configured to be coupled to the objective lens.

13. The microscope imaging system of claim 9 , wherein the lens housing includes first and second lens housing portions coupled to one another.

14. 2. The microscopy imaging system of claim 1, wherein the biological sample is contained within a flow cell, and the objective lens is configured to collect the light from the biological sample through a flow cell wall of the flow cell.

15. (a) the microscopy imaging system of claim 1; (b) a flow cell configured to contain a biological sample, the flow cell including a flow cell wall, and an objective lens configured to collect light from the biological sample through the flow cell wall; A biological analysis system comprising:

16. 16. The biological analytical system of claim 15, wherein the flow cell wall has a thickness between about 0.2 mm and about 2 mm.

17. (a) a flow cell configured to receive a biological sample, the flow cell comprising a flow cell wall having a thickness of about 1 mm; (b) a microscopy imaging system, comprising: (i) an infinity corrected objective lens configured to collect light from the biological sample through the flow cell wall to form a magnified image of the biological sample; (ii) a camera comprising an imaging sensor, the imaging sensor configured to detect the magnified image of the biological sample; and (iii) a tube lens disposed between the infinity corrected objective lens and the camera, the tube lens configured to project the magnified image of the biological sample onto the imaging sensor of the camera, the tube lens being spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens. A microscope imaging system comprising: A biological analysis system comprising:

18. 20. The biological analysis system of claim 17, wherein the infinity corrected objective lens is optimized to collect the light from the biological sample through a coverslip having a thickness of about 170 μm.

19. 1. A method of imaging a biological sample, comprising: (a) collecting light from the biological sample via an objective lens; (b) forming a magnified image of the biological sample through the objective lens; and (c) projecting the magnified image of the biological sample onto an imaging sensor of the camera via a tube lens disposed between the objective lens and a camera, the tube lens being spaced from the imaging sensor of the camera by a distance less than a focal length of the tube lens; (d) detecting the magnified image of the sample via the imaging sensor of the camera.

20. 21. The method of claim 20, wherein the objective lens is optimized to collect the light from the biological sample through a coverslip having a thickness of about 170 μm, and wherein collecting the light comprises collecting light from the biological sample through a flow cell wall having a thickness of about 1 mm.

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