MICROSCOPE

Abstract

A microscope (10) for detecting images of an object (14) located in an object plane (12) is described, comprising a microscope stand (18); a microscope objective (20); a light source (22) integrated into the microscope stand (18); and a beam splitter (24), integrated into the microscope objective (20), for coupling in a coaxial incident illumination.

Claims

1. A microscope (10) for detecting images of an object (14) located in an object plane (12), comprising: a microscope stand (18); a microscope objective (20); a light source (22) integrated into the microscope stand (18); and a beam splitter (24), integrated into the microscope objective (20), for coupling in a coaxial incident illumination.

2. The microscope according to claim 1, wherein the beam splitter (24) integrated into the microscope objective (20) is arranged in an observation beam path between the object plane (12) and an image plane (16) of the microscope (10), and in an illumination beam path between the light source (22) and the object plane (12), such that the light generated by the light source (22) is deflectable onto the object (14) located in the object plane (12).

3. The microscope (10) according to claim 1, wherein the observation beam path and the illumination beam path are at least in part coaxial.

4. The microscope (10) according to claim 1, wherein the beam splitter (24) is embodied such that the light generated by the light source (22) is couplable into the observation beam path.

5. The microscope (10) according to claim 1, wherein the beam splitter (24) is arranged relative to the light source (22) such that the light generated by the light source (22) is couplable laterally into the observation beam path, and the light couplable laterally into the observation beam path is deflectable onto the object (14) located in the object plane (12).

6. The microscope (10) according to claim 1, wherein a field diaphragm (30) and an aperture diaphragm are arranged in the illumination beam path between the light source (22) and the object plane (12), in a portion of the microscope stand (18) facing toward the microscope objective (20), such that a Köhler condition for illumination of the object (14) is satisfied.

7. The microscope (10) according to claim 1, wherein the light source (22) is imageable into a field plane and through the microscope objective (20) into the object plane (12), so that critical illumination of the object (12) is achievable.

8. The microscope according to claim 1, wherein a lambda/4 plate (26) is arranged between several objective lenses (40a-40d) arranged after the beam splitter (24) in the illumination direction; and the lens surfaces of the objective lenses (40c, 40d) that are arranged after the lambda/4 plate (26) in the illumination direction are embodied such that light reflected at the lens surfaces is deflected substantially out of the observation beam path.

9. The microscope (10) according to claim 1, wherein a refractive element (28) is integrated into the microscope objective (20), a portion of the microscope objective (20) facing toward the object plane (12) being arranged in the observation beam path between the object plane (12) and the image plane (16), and in the illumination beam path between the light source (22) and the object plane (12), the refractive element (28) integrated into the microscope objective (20) being arranged in front of the beam splitter (24) in the illumination direction, and in the illumination beam path between the light source (22) and the object plane (12) in a portion of the microscope objective (20) facing toward the light source (22), such that an illumination aperture corresponds to an objective aperture of the microscope objective (20).

10. The microscope (10) according to claim 9, wherein a contrasting element (36) is arranged in the microscope objective (20).

11. The microscope (10) according to claim 9, characterized wherein an interface (48) is integrated into the microscope objective (20), for inserting different contrasting elements.

12. The microscope according to claim 1, wherein the microscope objective is a removable microscope objective (20) that is mountable on and demountable from the microscope stand (18).

13. A microscope objective (20), comprising: a microscope objective housing (21); several objective lenses (40a-40d) arranged in the objective housing; and at least one beam splitter (24), integrated into the objective housing, for incoupling of a coaxial incident illumination.

14. The microscope objective according to claim 13, wherein the objective further comprises a lambda/4 plate (26), the plate (26) being integrated into the objective housing such that the plate (26) is arranged between several objective lenses (40a-40d) arranged after the beam splitter (24) in the illumination direction.

15. The microscope objective according to claim 14, wherein the lens surfaces of the objective lenses (40c, 40d) that are arranged after the lambda/4 plate (26) in the illumination direction are embodied such that light reflected at the lens surfaces is deflectable substantially out of an observation beam path.

16. The microscope objective according to claim 13, wherein the objective further comprises a refractive element (28) integrated into the objective housing (21), a portion of the microscope objective (20) facing toward an object plane (12) being arranged in an observation beam path between the object plane (12) and an image plane (16), and in an illumination beam path between the light source (22) and the object plane (12), the integrated refractive element (28) being arranged in front of the beam splitter (24) in the illumination direction, and in the illumination beam path between the light source (22) and the object plane (12) in a portion of the microscope objective (20) facing toward the light source (22), such that an illumination aperture corresponds to an objective aperture of the microscope objective (20).

17. The microscope objective according to claim 13, wherein the microscope objective is a removable microscope objective (20) that is mountable on and demountable from a microscope stand (18).

18. A microscope system, comprising: a microscope according to claim 1, a microscope objective comprising a microscope objective housing (21); several objective lenses (40a-40d) arranged in the objective housing; and at least one beam splitter (24), integrated into the objective housing, for incoupling of a coaxial incident illumination, and at least one further, removable, beam-splitter-free microscope objective (42), the working distance and/or focal length being longer when the beam-splitter-free objective (42) is mounted than when the objective (20) comprising the beam splitter is mounted.

Description

BRIEF DESCRIPTION OF THE DRAWING VIEWS

[0027] Further features and advantages of the invention are evident from the description below, which explains the invention in further detail with reference to exemplifying embodiments in conjunction with the attached Figures, in which:

[0028] FIG. 1 schematically depicts an exemplifying microscope for detecting images of an object located in an object plane, having an image sensor; and

[0029] FIG. 2 schematically depicts the exemplifying microscope according to FIG. 1 with imaging beam paths to illustrate critical illumination of the object.

DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 schematically depicts an exemplifying microscope 10, having an image sensor 16, for detecting images of an object 14 located in an object plane 12. Element 16 can also be assumed to be an intermediate image plane and thus an interface for a visual view into a microscope. As shown in FIG. 1, microscope 10 encompasses a microscope stand 18 and a microscope objective 20. Microscope stand 18 and microscope objective 20 represent two components, separate from one another, of microscope 10. Microscope 10 shown in FIG. 1 furthermore encompasses a light source 22 integrated into microscope stand 18. As shown in FIG. 1, image sensor 16 is a constituent of a detector 11 that is mounted on microscope stand 18. Alternatively, in a visual system a tube can also be provided. Image sensor 16 serves to detect two-dimensional images of object 14 located in object plane 12.

[0031] Also shown in FIG. 1 are the observation beam path between object plane 12 and image sensor 16, having axis 13, and the illumination beam path between light source 22 and object plane 12, having axis 15 at least in part coaxial with axis 13. The observation beam path and the illumination beam path are at least in part coaxial, the coaxial observation and illumination beam path being located perpendicularly to object plane 12. The illumination direction is defined as the direction of the light that is generated by light source 22 and propagates along illumination beam path 15 toward object plane 12.

[0032] As shown in FIG. 1, microscope objective 20 encompasses a portion facing toward light source 22 and a portion facing toward object plane 12. Microscope objective 20 furthermore encompasses an integrated beam splitter 24. Microscope objective 20 furthermore encompasses an integrated refractive element 28, which is arranged before beam splitter 24 in the illumination direction and in which that portion of microscope objective 20 which faces toward light source 22 is arranged. A contrasting element 36 is arranged between refractive element 28 and beam splitter 24. Microscope objective 20 furthermore encompasses an integrated lambda/4 plate 26 that is arranged after beam splitter 24 in the illumination direction and is arranged in that portion of microscope objective 20 which faces toward object plane 12. Lambda/4 plate 26 is arranged between several objective lenses 40a to 40d arranged after beam splitter 24 in the illumination direction. Objective lenses 40a, 40b are arranged before lambda/4 plate 26 in the illumination direction, while objective lenses 40c, 40d are arranged after lambda/4 plate 26 in the illumination direction. Working distance 17 corresponds to the distance between object plane 12 and end face 9, facing toward object plane 12, of microscope objective 20.

[0033] Microscope stand 18 encompasses a portion facing toward microscope objective 20. This portion of microscope stand 18 which faces toward microscope objective 20 encompasses optical elements 38a, 38b that are arranged after light source 22 in the illumination direction, and a field diaphragm 30 that is arranged after optical elements 38a, 38b in the illumination direction. That portion of microscope stand 18 which faces toward microscope objective 20 also encompasses a polarizer 32 that is arranged after field diaphragm 30 in the illumination direction. In addition, an analyzer 34 is arranged in observation beam path 13 between object plane 12 and image sensor 16, after beam splitter 24 in the light flow direction. Analyzer 34 is a constituent of detector 11 mounted on microscope stand 18.

[0034] The position of polarizer 32 shown in FIG. 1 is, by way of example, in stand 18. The polarizer can also be integrated into the objective. The analyzer can also be integrated into the stand rather than into the detector unit.

[0035] In addition to microscope objective 20, microscope 10 encompasses a further, beam-splitter-free microscope objective 42 having several objective lenses 44a to 44c. The microscope system shown in FIG. 1 encompasses in particular microscope objective 20 encompassing beam splitter 24, and the further, beam-splitter-free microscope objective 42. Microscope objectives 20, 42 are each removable microscope objectives. In addition, the focal length and/or working distance 19 is longer when beam-splitter-free objective 42 is mounted than when objective 20 encompassing beam splitter 24 is mounted.

[0036] For the case in which further microscope objective 42 is arranged in observation beam path 13 between object plane 12 and image sensor 16, a transmitted-light illumination, oblique illumination, or ring-light illumination is provided in microscope 10 alternatively or in addition to incident illumination. This alternative or additional illumination is not depicted in FIG. 1. The incident illumination is implemented by introducing microscope objective 20 into observation beam path 13 between object plane 12 and image sensor 16 in the manner depicted in FIG. 1.

[0037] With the arrangement shown in FIG. 1: light source 22 is a light-emitting diode (LED), optical elements 38a, 38b are special lenses for the illumination beam path, refractive element 28 is a planoconvex lens, and objective lenses 40a to 40d and 44a to 44c are lenses constituting an objective lens system of the respective microscope objective 20, 42.

[0038] Beam splitter 24 integrated into microscope objective 20 serves for lateral incoupling into observation beam path 13 of the light generated by light source 22. In addition, the light incoupled laterally into observation beam path 13 is deflected, using beam splitter 24, onto object 14 located in object plane 12. The fact that beam splitter 24 for incoupling the coaxial light into observation beam path 13 is integrated into microscope objective 20 makes possible an optimization of the overall system in terms of working distance. The light referred to as “coaxial light” is the light, coupled into the observation beam path, that is deflected onto object 14 located in object plane 12. Objectives that do not require a coaxial beam splitter, such as further microscope objective 42 shown in FIG. 1, can be implemented with a longer working distance and/or longer focal length, i.e. a greater variation in the magnification factor. The limited installation space for those objectives can thereby advantageously be utilized. In particular, an objective that (like microscope objective 42) does not require a beam splitter can be implemented in weight-optimized fashion and with less volume. This is advantageous for the user in that, inter alia, when such a microscope system is used on a tilting stand, the sample, for example a circuit board having tall components, can occupy a considerably larger volume without having the sample collide with the objective upon tilting.

[0039] Field diaphragm 30, arranged after light source 22 in the illumination direction, serves to furnish Köhler illumination of object 14 located in object plane 12. Field diaphragm 30 is arranged in such a way that the so-called “Köhler condition” for illumination of object 14 is satisfied. In order to provide different microscope objectives with light for full illumination of the object field, the coaxial beam path, i.e. the at least in part coaxial observation and illumination beam path, should satisfy the conditions derivable from the Köhler illumination principle for imaging the pupils and windows. If a strict correlation exists between pupils and fields, the extent of the light spot in field plane F ensures that the field is completely illuminated out to the edge. The maximum extent of the light spot in the aperture diaphragm plane determines the maximum illumination angle in the object. This illumination angle should be selected so that the beam reflected at the object is transmitted along the observation path to the detector (eye or camera).

[0040] So-called “critical illumination” can also be implemented in the coaxial beam path. Here light source 22 is imaged into a field plane F and, with microscope objective 20 or 42, into the vicinity of object plane 12, also referred to as a “specimen plane”. If the structure of the light proceeding from light source 22 is to be destroyed, this can occur, individually and specifically for each microscope objective, by frosting optical surfaces in that portion of microscope objective 20 (also referred to as the “illumination portion”) which faces toward light source 22.

[0041] FIG. 2 schematically depicts the exemplifying microscope 10 according to FIG. 1 with imaging beam paths 21a, 21b to illustrate critical illumination of the object. The object 14 located in object plane 12 is depicted in FIG. 2. Imaging beam paths 21a, 21b shown in FIG. 2 refer respectively to central rays and marginal rays of the light proceeding from light source 22.

[0042] Optical elements 38a, 38b arranged after light source 22 in the illumination direction are used to image light source 22 into field plane F and onto object plane 12.

[0043] After reflection at object 14 located in object plane 12, the corresponding beam paths 23a, 23b are produced for the reflected beams reflected toward detector 11. In particular, imaging beam paths 21a, 21b are depicted only schematically in FIG. 2. The reflected beam paths are also not depicted all the way to image sensor 16 of detector 11.

[0044] Lambda/4 plate 26 integrated into microscope objective 20 serves to influence the polarization direction of the light passing through lambda/4 plate 26. Polarizer 32 and analyzer 34 are furthermore embodied as crossed polarizers; in other words, the passthrough direction of analyzer 34 is rotated 90° with respect to the polarization direction generated by polarizer 32. Polarizer 32, lambda/4 plate 26, and analyzer 34 result in improved bright-field polarization microscopy. Improved bright-field polarization microscopy is achieved in particular by attaching and appropriately orienting lambda/4 plate 26. In addition, dark-field polarization microscopy can also be implemented by removing or rotating lambda/4 plate 26, lambda/4 plate 26 being rotated 45° as compared with the position for bright-field polarization microscope.

[0045] In order to implement improved bright-field polarization microscopy, polarizer 32, lambda/4 plate 26, and analyzer 34 are configured in such a way that the polarization direction of the light that is reflected at object 14 located in object plane 12, and passes through lambda/4 plate 26 in the direction of image sensor 16, and strikes analyzer 34, corresponds to the passthrough direction of analyzer 34. The polarization direction, established by polarizer 32, of the light that is generated by light source 22 and passes through lambda/4 plate 26 in the direction of object plane 12, after reflection at object 14 located in object plane 12 and passage again through lambda/4 plate 26 in the direction of image sensor 16, is rotated 90° with the aid of lambda/4 plate 26. Conversely, the polarization direction, effected by polarizer 32, of the light that is generated by light source 22, and is reflected at lens surfaces of objective lenses 40a, 40b arranged in front of lambda/4 plate 26 in the illumination direction, and strikes analyzer 34 after reflection, is not rotated. In addition, the lens surfaces of objective lenses 40c, 40d arranged after lambda/4 plate 26 in the illumination direction are so strongly curved that light reflected at them is deflected out of the observation beam path. The result is that only the light reflected at object 14 located in object plane 12, said light passing through lambda/4 plate 26 twice (i.e. in the illumination direction and in a direction opposite to the illumination direction), is allowed by analyzer 34 to pass, so that that light is detected by image sensor 16. The light reflected at the lens surfaces of objective lenses 40a to 40d, however, does not arrive at image sensor 16 of detector 11.

[0046] In particular with the arrangement shown in FIG. 1 of lambda/4 plate 26 between the several objective lenses 40a to 40d, the objective lenses 40c, 40d that are arranged after lambda/4 plate 26 in the illumination direction are objective lenses having a high refractive power. This has the advantage, in terms of optical design, that the refractive power of the objective lenses can be positioned at the lower end of microscope objective 20, and working distance 17 can thus be extended. This embodiment is advantageous in particular for objectives having high refractive power and thus strong radii of curvature in the lower lenses.

[0047] Alternatively to the arrangement shown in FIG. 1, lambda/4 plate 26 is preferably arranged at that end of microscope objective 20 which faces toward object plane 20. In other words, in this case lambda/4 plate 26 is arranged after all the objective lenses 40a to 40d in the illumination direction. This prevents reflections from lens surfaces of all these objective lenses 40a to 40d from arriving at image sensor 16 of detector 11.

[0048] The exemplifying coaxial illumination prevents illuminating light, reflected at lens surfaces of objective lenses arranged in the observation beam path, from producing an intrusive bright background in the resulting image. This is prevented by introduction of the crossed polarizers, i.e. polarizer 32 and analyzer 34. Polarizer 32 arranged in the illumination beam path is oriented crosswise to analyzer 34 arranged in the observation beam path. No illumination light can therefore reach image sensor 16 as long as the polarization state of the light is not rotated.

[0049] According to a preferred exemplifying embodiment of the invention, two microscopy methods are made possible in particular. These are dark-field polarization microscopy and bright-field polarization microscopy.

[0050] In the preferred embodiment of dark-field polarization microscopy, the two polarizers 32, 34 are configured in such a way that all light is blocked if its polarization is not disturbed. In this application, polarization disturbance occurs only as a result of interference sites on an otherwise reflective specimen, so that the observer obtains a predominantly dark image with bright interference sites.

[0051] In the preferred embodiment of bright-field polarization microscopy, polarizer 32, lambda/4 plate 26, and analyzer 34 are configured in such a way that the light passes through lambda/4 plate 26 twice, i.e. through and back, with the result that the polarization direction of the returning light is rotated 90°. The observer then obtains a predominantly bright image, since the illuminating light that is reflected back from object 14 is rotated into the passthrough direction of analyzer 34.

[0052] The following advantages are obtained thanks to the provision of lambda/4 plate 26 as an integrated constituent of microscope objective 20: The clear working distance between objective and object can be extended. Optical image quality can be enhanced, since a lambda/4 plate does not need to be introduced below the objective, generating unavoidable spherical and chromatic aberrations. Even high-magnification and high-resolution objectives can be equipped with the integrated lambda/4 plate. In the embodiment in which the lambda/4 plate is arranged not as the lowest element but instead between the lens elements of the objective, reflections from the lens surface that follow below it can in principle once again be observed, but this embodiment has the advantage that it becomes possible to place the refractive power of the lenses at the lower end of the objective.

[0053] Preferably the lambda/4 plate is mounted rotatably. The ratio of polarization-receiving reflected light and non-polarization-receiving remitted light in the image can thereby be controlled. This allows the switchover between the bright-field and dark-field scenarios described above.

[0054] The lambda/4 plate is typically rotatable. Its effect on polarization can thus be adjusted arbitrarily. In particular, the polarizer or polarizing filter in the illumination beam path, and the analyzer in the observation beam path, are permanently preset at the factory at 90° to one another. In addition, the lambda/4 plate can be introduced at the aforesaid location, making it possible, after rotatable adjustment, for the light that is reflected back from the object to be rotated into the passthrough direction of the analyzer. If the lambda/4 plate is rotated 45° with respect to that active position, it then effectively does nothing, i.e. the light is blocked by the analyzer (as if no lambda/4 plate were introduced).

[0055] Refractive element 28 integrated into microscope objective 20 serves to adapt the illumination aperture to the objective aperture of microscope objective 20. Refractive element 28 is selected so that the illumination aperture for coaxial illumination corresponds to the objective aperture of microscope objective 20 respectively arranged in the observation beam path. There is thus no need for a complicated illumination arrangement for coaxial illumination of different objectives each having a different objective aperture. The fact that the illumination aperture corresponds respectively to the objective aperture of microscope objective 20 prevents a decrease in the resolution capability of the respective microscope objective 20. It is advantageous in this context that a portion of the optical system of the illumination branch, i.e. refractive element 28 arranged in that portion of microscope objective 20 which faces toward light source 22, is an integral constituent of the respective microscope objective 20. This portion is therefore exchanged along with the objective, and permits individual adaptation of the illuminating beams for each objective.

[0056] A refractive power defined individually for each objective with the aid of the integrated refractive element 28 furthermore makes it possible to carry out a specific adaptation of the coaxial beam path in such a way that, for example, homogeneity in object plane 12 is improved.

[0057] Oblique illumination can be implemented by introducing contrasting element 36 into the illumination beam path between refractive element 28 and beam splitter 24. The geometry of contrasting element 36 can encompass, for example, a sickle-shaped or round geometry, or a geometry having a straight edge. In particular, this geometry can be adapted to the conditions of the respective objective.

[0058] The exemplifying microscope 10 encompasses in particular: a beam splitter integrated into the objective for incoupling the illumination, and at least one refractive power, integrated into the objective, of the illuminating beam path; a contrasting element integrated permanently into the objective; an interface 48, integrated into the objective, for inserting various contrasting elements; or a lambda/4 plate integrated into the objective, the lambda/4 plate being rotatably mounted.

[0059] The preferred embodiment implements an illumination interface in a microscope. In particular, an illumination interface is furnished between the microscope stand and the object located in the object plane. The illumination interface corresponds here to the beam splitter integrated into the objective, the lambda/4 plate integrated into the objective, and the refractive element integrated into the objective. Simple and flexible adaptation of different objectives is made possible with the aid of the defined illumination interface, thanks to the physical separation of the illumination source and objective. The light source is integrated into the stand, which yields advantages in terms of heat dissipation since the thermal sensitive observation optics or objective are arranged physically, and thus thermally, in a manner clearly separated from the light source. The contrasting unit is integrated into the objective and can thus be specifically configured for the conditions in the objective.

PARTS LIST

[0060] 10 Microscope

[0061] 11 Detector

[0062] 12 Object plane

[0063] 13, 15 Axis of beam path

[0064] 21a, 21b, 23a, 23b Beam path

[0065] 14 Objective

[0066] 16 Image sensor or image plane

[0067] 17, 19 Working distance

[0068] 18 Microscope stand

[0069] 20, 42 Microscope objective

[0070] 21 Microscope objective housing

[0071] 22 Light source

[0072] 24 Beam splitter

[0073] 26 Lambda/4 plate

[0074] 28 Refractive element

[0075] 30 Field diaphragm

[0076] 32 Polarizer

[0077] 34 Analyzer

[0078] 36 Contrasting element

[0079] 38a, 38b Optical elements

[0080] 40a to 40d, 44a to 44c Objective lenses

[0081] 46 Field margin

[0082] 48 Contrasting element interface

[0083] F Field plane