Microscope objective and microscope

Abstract

Microscope objective (1, 100, 200) with a first lens unit (3, 103, 203), at least one second lens unit (5, 105, 205) and a real pupil (7, 107, 207, wherein - the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205) are arranged spaced apart from each other along an optical axis (OA) of the lens, so that there is a space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205), and the second lens unit (5, 105, 205) is arranged image-side to the first lens unit (3, 103, 203); - the first lens unit (3, 103, 203) is designed in such a way that it produces a collimated beam of rays; - the real pupil (7, 107, 207) is located in the space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205), characterized in that it has a numerical aperture of at least 0.8.

Description

[0001] The present invention relates to a microscope objective comprising a first lens unit, at least one second lens unit, and a pupil. The invention also relates to a microscope.

[0002] Optical observation devices such as microscopes, endoscopes, etc., typically feature lenses optimized for their respective applications. Adding another optical element to the lens usually requires a redesign of the lens. This means that such lenses can often only be used optimally within a narrow range of observation conditions, because they cannot be flexibly adapted to other observation conditions.

[0003] For example, in microscopy with high-aperture objectives such as immersion objectives, where a liquid film forms between the objective and the coverslip covering the sample, high lateral resolution is accompanied by a shallow depth of field on the object side. While the smallest laterally resolvable structure d min at diffraction-limited resolution according to the equation dmin∼λNA At a wavelength λ that varies proportionally to the inverse of the numerical aperture NA, the longitudinal resolution l, also called depth of field, varies according to the equation l∼λNA2 proportional to the inverse of the square of the numerical aperture. The depth of field given by the last equation for a wavelength λ is also called the Rayleigh length or Rayleigh unit (RE). As can be seen from the two equations, the usable depth of field decreases rapidly when the numerical aperture (NA) is increased to improve the lateral resolution. Therefore, in order to acquire image information of the entire object volume with diffraction-limited resolution when microscopy three-dimensionally extended sample areas, such as entire cells within natural tissues or cell organelles embedded in physiological saline solution, it is necessary to acquire up to several hundred so-called Z-sections. A Z-section represents an image of high lateral resolution at a predetermined focus position, i.e., at a specific depth of the object. From the individual Z-sections, it may be possible to...Using image processing methods, a two-dimensional image with increased depth of field can be generated, which can then be displayed on an image display device. The focus positions of the Z-scans can be adjusted by refocusing the microscope.

[0004] Refocusing the microscope, for example by adjusting the stage relative to the microscope, induces significant image aberrations at the microscope objective, as the objective is optimized for a specific focus position. Modifying the objective to optimize it for a different focus position typically requires extensive modification of its optical components.

[0005] The image aberrations that arise during refocusing can be conceptually divided into two types: those that exhibit large but predictable magnitudes at a medium wavelength and those that exhibit a predictable chromatic dependence. Examples of the first type of aberration are different orders of aperture error, i.e., different orders of spherical aberration. Examples of the second type of aberration include, in particular, longitudinal chromatic aberration (CHL) as a primary, secondary, and tertiary spectrum. Similarly, aberrations are induced when refocusing is performed by changing the focal length of the lens using an internal focusing lens. In both cases, the image quality deteriorates drastically even with a slight change in the object distance or focal length. A slight change is already present when the object distance or focal length is changed by a factor of 1.A change in the focal length of a few Rayleigh units is possible. However, adding elements that could compensate for the deterioration in image quality requires a significant change in the optical design of the lens.

[0006] US Patent 4,457,592 A describes a lens with a first lens unit and a second lens unit, as well as a physical aperture diaphragm located between the two lens units. An Alvarez element is located between the two lens units, near the aperture diaphragm.

[0007] US patent 2007 / 0247725 A1 describes a zoom lens system with a wavefront manipulator.

[0008] It would therefore be desirable to have a microscope objective that can be easily optimized for different observation conditions without having to change the design of its optical components.

[0009] The object of the present invention is to provide an advantageous microscope objective that offers the possibility of adding at least one element with which the microscope objective can be adapted to different observation conditions, without requiring a redesign of the microscope objective. A further object of the present invention is to provide an advantageous microscope.

[0010] The first problem is solved by a microscope objective according to claim 1, the second problem by a microscope according to claim 17.

[0011] A microscope objective according to the invention comprises a first lens unit, which may be configured as a single lens or a lens group, at least one second lens unit, which may also be configured as a single lens or a lens group, and a real pupil, which may be realized by a physical aperture diaphragm or the real image of a beam-limiting opening. The first lens unit and the second lens unit are arranged at a distance from each other along an optical axis of the microscope objective (which may optionally be folded), such that a space exists between the first lens unit and the second lens unit. The real pupil is located in the space between the first lens unit and the second lens unit.

[0012] The first lens unit is designed to produce a collimated beam of light. In other words, the first lens unit projects an object-side image field telecentrically to infinity. A beam of light is considered collimated when the marginal rays form an angle of no more than 5°, preferably no more than 3°, with the optical axis of the microscope objective. If an image with particularly low aberrations is desired and / or if a very high aperture microscope objective (NA ≥ 1.0) is used, it is advantageous if the marginal rays form an angle of no more than 2° with the optical axis of the microscope objective.

[0013] The microscope objective according to the invention thus has an accessible real pupil and a collimated beam of light present at the pupil. An accessible real pupil is understood here to be a real pupil that is not located within other optical components of the microscope objective, so that the microscope objective allows the arrangement of at least one pupil filter in the region of the pupil. At least one pupil filter could, in particular, be a wavefront manipulator, a phase mask such as an annular phase plate for carrying out a Zernike phase contrast method, an apodization filter, a spectral filter, a spatial light modulator (SLM), etc., or combinations thereof.Unlike prior art microscope objectives, the microscope objective according to the invention allows the insertion of such pupil filters without requiring any significant changes to the design of the other optical components of the microscope objective. The space between the first and second lens units thus provides a kind of internal interface for pupil filters, thanks to the arrangement of the real pupil within this space. The microscope objective according to the invention is therefore advantageous in that it enables a quasi-modular design in conjunction with pupil filters. By arranging at least one pupil filter in the space between the first and second lens units, the microscope objective can be optimized for specific observation conditions or adapted to other applications.

[0014] In an advantageous embodiment of the invention, the first lens unit of the microscope objective fulfills the condition for all rays of an aperture beam. |h1−fFG⋅sin σ0h1|≤x, where x = 0.3, preferably x = 0.2, and more preferably x = 0.1. Here, h1 denotes the incidence height of the aperture beam at the wavefront manipulator, and σ0 the beam inclination angle of the marginal beam relative to the optical axis. fFG=−n0⋅fFG' the front (object-side) focal length of the first lens unit, and n0 the refractive index of the medium or immersion medium between the object and the first lens unit.

[0015] To achieve particularly good image quality with microscope objectives according to the invention, and especially with high-aperture microscope objectives according to the invention (NA ≥ 0.8), the marginal rays of all rays of an aperture bundle located within 71% of the pupil radius (corresponding to a circular area of ​​50% of the total pupil area) should exhibit a deviation of no more than half the limits specified in the respective inequality. In other words, the rays should satisfy the above inequality for in the region within 71% of the pupil radius, or preferably for and further preferably for .

[0016] The inequality above states that the optical sine condition is approximately satisfied, thus preventing redistribution of the rays within the pupil. This prevents the rays from striking the wavefront manipulator at the wrong location at the edge or in the central regions of the pupil. The smaller the value of x, the better the sine condition is fulfilled.

[0017] In the case of a microscope objective with an extremely high aperture (NA ≥ 1.0), it can be advantageous with regard to image quality if, in the above inequality, x = 0.1, preferably and further preferably x = 0.1, holds true for all rays of an aperture beam that lie within 71% of the pupil radius. In this case, the rays between 71% and 100% of the pupil radius should still satisfy the above inequality at least for , preferably for , and further preferably for x = 0.1.

[0018] Fulfilling the above formula can be achieved in particular if the first lens unit comprises an aspherical lens. With such a lens, the sine condition can be fulfilled simply and quite accurately.

[0019] The use of at least one aspherical lens is particularly advantageous in microscope objectives with high aperture or large aperture angles, and then helps not only in correcting the usual spherical aberration, i.e. spherical aberration, but also in complying with the sine condition in the first lens unit.

[0020] It should be noted here that the sine condition is usually fulfilled for an entire microscope objective, as otherwise a sharp image of an extended field of view would not be possible. However, fulfilling the sine condition for individual lens units of the microscope objective is typically neither necessary nor common. Furthermore, unlike the microscope objective according to the invention, the pupil in prior art microscope objectives is generally located in the region of the objective's exit point.

[0021] The first lens assembly of the microscope objective can also be designed to be telecentric on the object side. The first lens assembly is considered telecentric on the object side if the angle of a principal ray (i.e., the central ray of a beam, also called the centroidal ray) from an object point at the edge of the field of view with the optical axis is less than 3°, and preferably less than 1°. The angle between such a principal ray and the optical axis is also called the telecentricity error.

[0022] As mentioned earlier, refocusing a microscope, for example by adjusting the stage relative to the microscope, causes significant image aberrations at the microscope objective. These aberrations drastically degrade the image quality even with slight changes in the object distance or focal length. A change in object distance or focal length of just a few Rayleigh units is considered slight.

[0023] In addition to the intended changes in focus position during Z-scans, changes in focus position also occur due to external influences. For example, thermally induced or otherwise caused fluctuations in the refractive index of optical media typically cause changes in the system's refractive power, which can also exhibit a wavelength dependency. While the change in refractive power at a mean wavelength can usually be adequately compensated for by a sliding lens, changes in air space, or other suitable mechanisms to compensate for defocus errors, the wavelength dependency of the defocus remains as a residual error that cannot be compensated for otherwise.Furthermore, changes in the refractive index of the immersion medium cause not only a focus shift at the fundamental wavelength—which, as mentioned above, could be compensated for by conventional refocusing—but also spherical aberration, which is very difficult to compensate for using conventional methods. Disturbing spherical aberration always occurs when the phase thickness of the immersion medium, i.e., its spatial thickness multiplied by its refractive index, changes in the divergent beam path in front of the microscope objective, since the basic objective can only ever be designed for a fixed phase thickness of the immersion medium.

[0024] The difficulties described above can be overcome with an advantageous further development of the microscope objective according to the invention. In this further development, at least one wavefront manipulator is located in the space between the first lens unit and the second lens unit as a pupil filter. This wavefront manipulator comprises a first optical component with at least one refractive freeform surface or a diffractive surface and at least one second optical component with at least one refractive freeform surface or a diffractive surface. The first optical component and the second optical component are arranged one behind the other along the optical axis and are each movable relative to each other in a direction of movement perpendicular to the optical axis. Wavefront manipulators with refractive freeform surfaces are described, for example, in US 3,305,298, and those with diffractive surfaces in IM Barton et al., "Diffractive Alvarez Lens," OPTICS LETTERS Vol. 25, No.This information was published on January 1, 2000. Regarding possible configurations and the construction of the wavefront manipulators, reference is therefore made to these documents.

[0025] The described advanced training provides an adaptive microscope objective with which the optical effect of at least one variable influencing factor in a given application can be compensated, whereby the adaptive microscope objective exhibits an almost constant and diffraction-limited image quality across the entire adjustment range.

[0026] The wavefront manipulator can be positioned in the space between the first and second lens units such that the real pupil is located at the wavefront manipulator. Alternatively, it can be positioned so that the real pupil is located in the space between the first and second lens units, either in front of or behind the wavefront manipulator, in which case the wavefront manipulator should be positioned as close as possible to the pupil. If the wavefront manipulator is located at the pupil, the pupil can be situated, in particular, between the first and second optical components of the wavefront manipulator. It is especially advantageous if the pupil is designed as a real image of a beam-limiting aperture, as it then requires no installation space in the area of ​​the wavefront manipulator.Furthermore, a real image can be positioned more freely within the wavefront manipulator than a physical aperture diaphragm, since the image can, in principle, be located within the first or second optical component. With a physical aperture diaphragm, however, the wavefront manipulator is preferably positioned directly in front of or behind the aperture diaphragm. Positioning it in front of or behind the aperture diaphragm is advantageous because the optical components of the wavefront manipulator can be arranged closer together than would be the case with a physical aperture diaphragm positioned between the optical components. However, a physical aperture diaphragm can also be positioned between the optical components of the wavefront manipulator if sufficient space is available between them.

[0027] With the described further development of the microscope objective according to the invention, at least one image aberration, such as focusing, spherical aberration, astigmatism, or coma, can be continuously and variably adjusted, while the other image aberrations remain essentially unaffected. The continuous adjustability of the image aberration makes it possible, for example, to eliminate image aberrations caused by changes in the focus position by adjusting a corresponding compensating image aberration using the wavefront manipulator. For example, defocusing caused by a change in the focus position can be compensated for by a corresponding negative defocus generated using the wavefront manipulator, provided the wavefront manipulator has suitable freeform surfaces.Accordingly, other externally caused image aberrations, such as astigmatism or coma, can also be compensated by inducing a corresponding negative image aberration using a wavefront manipulator with suitably designed freeform surfaces, which cancels out the externally caused aberration. More generally, the wavefront manipulator in the adaptive microscope objective according to the invention can be used to change at least one predetermined monochromatic aberration coefficient at a given reference wavelength. In particular, it can be designed such that the change in the corresponding aberration coefficient varies as little as possible across the wavelength range used for imaging, thus enabling the realization of an achromatic wavefront manipulator.However, it can also be designed in such a way that it allows for the targeted adjustment of the chromatic aberration coefficient of the wavefront of a beam of light. In particular, this enables variable adjustment of the primary or secondary longitudinal chromatic aberration (CHL) of the microscope objective.

[0028] By using the wavefront manipulator and its arrangement in the microscope objective according to the invention, a high-aperture microscope objective, i.e., a microscope objective with a numerical aperture of at least 0.8 and, in particular, at least 1.0, can be designed such that high-quality imaging is ensured over a wide range of adjustment of the aberration coefficient. In particular, the present invention also makes it possible to design such an adaptive microscope objective in such a way that it enables diffraction-limited imaging. Of particular importance here is that the objective-side guiding lens unit generates a collimated beam of light and the wavefront manipulator is arranged between the two lens units in the region of the collimated beam of light.

[0029] With the previously described further development of the adaptive microscope objective according to the invention, it is possible to influence an image aberration (represented by an aberration coefficient) independently of the other image aberrations. In almost all practically relevant cases, however, it is also desirable to keep the optical image largely free of chromatic aberrations across the entire focusing range. This is, however, very difficult to achieve with conventional means, if at all. For example, thermally or otherwise caused fluctuations in the refractive index of an optical medium often produce changes in the system's refractive power that exhibit a strong wavelength dependence. While the change in refractive power at a mean wavelength can usually be compensated for by a known defocus compensator (e.g., a sliding lens, a change in the air space between two lenses, etc.),Although the wavelength dependence of the defocus can be adequately compensated, it remains as a residual error that cannot be compensated for otherwise. Therefore, a further development of the adaptive microscope objective with wavefront manipulator also allows for a reduction in the wavelength dependence of the compensating image error. To achieve this, an immersion medium can be placed between the first and second optical components of the wavefront manipulator, allowing contact between the two components. Without such a measure, a variable chromatic aberration can occur when adjusting the aberration coefficient. This would essentially manifest as longitudinal chromatic aberration (CHL).In other words, while monochromatic aberrations, such as defocus, could be compensated independently of other aberration coefficients, the set compensating defocus could lead to different focal lengths at different wavelengths. As long as the focal length differences are not too large when using compensating defocus, this has little to no impact on the image. However, if large deviations in focal length occur, this can lead to longitudinal chromatic aberration, noticeably degrading image quality. Similar considerations apply to the other monochromatic aberrations, since the compensating aberration set using the wavefront manipulator also exhibits a wavelength dependency in these cases.

[0030] Suitable immersion media include liquids such as highly purified water, saline solutions, immersion oils, etc., and elastic opto-cements. Since only lateral movement of the first and second optical components occurs, the wavefront manipulator with immersion medium can have a flat design, i.e., a small dimension perpendicular to the lateral direction of movement.

[0031] By appropriately matching the refractive index and Abbe number of the immersion medium to the refractive index and Abbe number of the material from which the optical elements are made, a variably adjustable wavefront manipulation can be achieved. The effect of this manipulation is independent of the wavelength over an extended wavelength range, allowing the wavefront manipulator according to the invention to be used as an achromatic wavefront manipulator. With this design of the wavefront manipulator, the chromatic aberrations described above, particularly longitudinal chromatic aberration, can therefore be largely avoided when the compensating image error is set.

[0032] If the immersion medium or the material of the first and second optical components of the wavefront manipulator exhibits a dispersion pattern that deviates from the normal line, higher orders of chromatic aberration, i.e., secondary and tertiary spectra of chromatic aberration, can also be corrected. For the correction of tertiary chromatic aberration, both the immersion medium and the material of the wavefront manipulator components must exhibit a dispersion pattern that deviates from the normal line.

[0033] In a particular embodiment of the microscope objective with wavefront manipulator according to the invention, at least one second wavefront manipulator is arranged between the first lens unit and the second lens unit. With the second wavefront manipulator, a second image aberration can be corrected independently of the other image aberrations, as has already been described with reference to the first wavefront manipulator. By increasing the number of wavefront manipulators located between the first and second lens units, any number of image aberrations can be corrected independently of one another. The design of the wavefront manipulators is governed by the same principles as described above regarding the possible design of the wavefront manipulator. The lateral movements of the optical components of at least two wavefront manipulators can also be coupled.

[0034] In the microscope objective according to the invention, the second lens unit can be designed to be afocal, i.e., it neither converges nor diverges, so that parallel incident beams also exit as parallel beams. In this way, an afocal optical interface can be provided, which makes it possible to freely combine the microscope objective with various other optical systems. For example, a suitably designed afocal microscope objective can be freely combined with different microscope tube systems. Such an interface is also called an infinity interface.

[0035] The microscope objective according to the invention can, in particular, be a microscope objective designed to interact with an immersion medium adjacent to the first lens unit on the object side. In this way, microscope objectives with high numerical apertures (NA ≥ 0.8) to very high numerical apertures (NA ≥ 1.0) can be realized.

[0036] According to a further aspect of the invention, a microscope with a microscope objective according to the invention is provided. The advantages and properties described with regard to the microscope objective according to the invention can thus be realized in the microscope according to the invention.

[0037] If the microscope objective has an infinity interface, a third lens unit can be attached to it, which, together with the first and second lens units, produces a real intermediate image that can either be viewed visually magnified or captured by an image receptor. Such a third lens unit can, in particular, be designed as a tube lens group.

[0038] Further features, properties and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Fig. Figure 1 shows the basic structure of a microscope objective according to the invention. Fig. Figure 2 shows a special design of the wavefront manipulator, as it can be used in the microscope objective. Fig. Figure 3 shows an alternative embodiment for the microscope objective according to the invention. Fig. Figure 4 shows another embodiment of the microscope objective according to the invention. Fig. Figure 5 shows a first concrete example of a microscope with a microscope objective according to the invention. Fig. Figure 6 shows the microscope objective. Fig. 5 in a first position of the optical component of the wavefront manipulator relative to each other. Fig. Figure 7 shows the microscope objective from Fig. 5 in a second position of the optical components of the wavefront manipulator relative to each other. Fig. Figure 8 shows the microscope objective from Fig. 5 in a third position of the optical components of the wavefront manipulator relative to each other. Fig. Figure 9 shows the design data of the microscope. Fig. 5 in tabular form. Fig. Figure 10 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. position shown in 6. Fig. Figure 11 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. 7 is in the position shown. Fig. Figure 12 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. position shown in 8. Fig. 13, Fig. 14 to Fig. Figure 15 shows the wavefront errors that arise in the microscope objective from the Fig. 6, Fig. 7 to Fig. 8 would occur without the wavefront manipulator Fig. Figure 16 shows a second concrete example of a microscope with a microscope objective according to the invention. Fig. Figure 17 shows the microscope objective from Fig. 16 in a first position of the optical component of the wavefront manipulator relative to each other. Fig. Figure 18 shows the microscope objective from Fig. 16 in a second position of the optical components of the wavefront manipulator relative to each other. Fig. Figure 19 shows the microscope objective from Fig. 16 in a third position of the optical components of the wavefront manipulator relative to each other. Fig. Figure 20 shows the design data of the microscope. Fig. 16 in tabular form. Fig. Figure 21 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. Position 17 is shown. Fig. Figure 22 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. Position shown in 18. Fig. Figure 23 shows the wavefront errors caused by the microscope objective when the wavefront manipulator is in the Fig. position shown in 19.

[0039] A first embodiment of a microscope objective according to the invention is described in Fig. Figure 1 shows a schematic embodiment. This schematic embodiment simultaneously illustrates the simplest structure of the microscope objective according to the invention and enables a basic understanding of its operation. The microscope objective 1 of the first embodiment, which is designed as an adaptive microscope objective, comprises a single lens 3 as the first lens unit, a single lens 5 as the second lens unit, an aperture diaphragm 7, and a wavefront manipulator 9, all of which are arranged along an optical axis OA of the microscope objective. The wavefront manipulator 9 is located between the first lens 3, which represents the object-side lens of the microscope objective 1, and the second lens 5, which represents the image-side lens of the microscope objective. The aperture diaphragm 7 is arranged immediately adjacent to the wavefront manipulator 9. In the present embodiment, it is positioned downstream of the wavefront manipulator 9 in the direction of the image-side lens 5.Alternatively, it can also be positioned in front of the wavefront manipulator 9 in the direction of the object-side lens 3. If the microscope objective 1 is designed such that the aperture diaphragm is the real image of a diaphragm, the virtual diaphragm can also be located at the position of the wavefront manipulator 9.

[0040] The wavefront manipulator 9 has two optical components 11, 13, each possessing a planar surface 14, 16 and a freeform surface 15, 17. In the present embodiment, the optical components 11, 13 of the wavefront manipulator 9 are arranged relative to each other such that the freeform surfaces 15, 17 are opposite each other. The planar surfaces 14, 16 then form the input surface to the wavefront manipulator 9 and the output surface from the wavefront manipulator 9, respectively. Fig. It should be noted that the extent of the wavefront manipulator and the profile depths of the freeform surfaces are exaggerated for the sake of clarity in the figures.

[0041] The optical components 11, 13 of the wavefront manipulator 9 are arranged one behind the other in the direction of the optical axis OA and are laterally displaceable relative to each other, i.e., perpendicular to the optical axis, as indicated in the figure by the arrows -y and +y. In the zero position shown in the figure, the refractive freeform surfaces 11, 13 are exactly complementary to each other, so that in this position the two optical components essentially exhibit the optical effect of a plane-parallel plate, i.e., an optical zero element.

[0042] The optical components 11 and 13 can be made of glass, plastic, or crystalline material, for example. The choice of material can depend, in particular, on the intended use of the wavefront manipulator 9 in the microscope objective 1. If the microscope objective is used in the visible optical spectral range, glass or plastic will generally be chosen. If the microscope objective is to be used in the ultraviolet spectral range, the components 11 and 13 can be made of quartz glass or a crystalline material such as calcium fluid or barium fluid, for example.

[0043] As from Fig. As can be seen in Figure 1, a collimated beam path exists in the microscope objective 1 between the object-side lens 3 and the image-side lens 5; that is, the object-side image field O is imaged to infinity by the object-side lens 3. A beam of light can be considered sufficiently collimated if its marginal rays form an angle of no more than 5° with the optical axis of the microscope objective. A beam of light can be considered to be collimated to a good approximation if its marginal rays form an angle of no more than 3° with the optical axis of the microscope objective, and to be collimated to a very good approximation if its marginal rays form an angle of no more than 2° with the optical axis of the microscope objective.The very good approximation of 2° is particularly advantageous when especially low, unintentionally induced image aberrations are desired and / or when the microscope objective has a very high aperture, i.e., a numerical aperture (NA) ≥ 1.0.

[0044] Furthermore, the object-side lens 3 is designed such that it approximately fulfills Abbe's sine condition. This is stated as follows: h1=fFG⋅sin σ0=n0⋅fFG'⋅sin σ0

[0045] It can be considered a sufficient approximation if, for all rays of a beam of light that are within 71% of the maximum pupil radius, the value of the expression f FG· sin σ0 deviates from the value of h1 by no more than 15% of the value of h1, as a good approximation if it deviates by no more than 10%, as a very good approximation if it deviates by no more than 5%, and as an excellent approximation if it deviates by no more than 3%. In other words, the first lens unit of the microscope objective satisfies the condition for all rays of an aperture beam that lie within 71% of the pupil radius. |h1−fFG⋅sin σ0h1|≤x, where x = 0.15, preferably x = 0.1, further preferably x = 0.05 and in particular x = 0.03.

[0046] The rays of a beam of light that are within 71% of the maximum pupil radius enter the inner circular area of ​​the pupil that makes up 50% of the pupil area.

[0047] In the prior art, the sine condition is typically fulfilled by a microscope objective as a whole, since this is necessary to generate a sharp image of both objects located on the optical axis OA and objects located outside the optical axis OA. In the microscope objective according to the invention, the first lens unit, which is a subunit of the objective lens system, also fulfills the sine condition. Fulfillment of the sine condition by the object-side lens unit of the microscope objective prevents redistribution of the rays in the pupil, which would cause the rays at the edge or center of the pupil to strike the wavefront manipulator at the wrong location.

[0048] It should be noted at this point that it is clear to a person skilled in the art that an optical system cannot produce a perfectly collimated beam path, but only an approximation, and that the sine condition can also only be fulfilled approximately, not exactly. Therefore, when the exemplary embodiments of the present invention refer to a collimated beam path or the fulfillment of the sine condition, this should always be understood to mean that a beam path is sufficiently collimated or that the sine condition is fulfilled to a sufficiently approximate degree.

[0049] In the adaptive microscope objective 1, the wavefront manipulator 9 serves to induce defined image aberrations that cancel out image aberrations generated in the microscope objective by external conditions, such as variations in focus position or temperature variations. The generation of a defined image aberration is achieved by manipulating the wavefront of the beam. The wavefront of a beam is defined by the points of the electromagnetic wave that have the same phase. Mathematically, the wavefront can be represented by a superposition of functions from a complete system of functions. Typically, Zernike polynomials are used as the system of functions, with each Zernike polynomial representing a different image aberration. In the wavefront representation, each Zernike polynomial is assigned a Zernike coefficient, and the wavefront is described by these Zernike coefficients.The freeform surfaces 15, 17 of the optical components 11, 13 of the wavefront manipulator 9 can be chosen such that they generate a wavefront manipulation that can be described by a Zernike polynomial. The corresponding Zernike coefficient is determined by the magnitude of the relative displacement of the two optical components 11, 13. A mathematically equivalent description can also be achieved by expansion in terms of other complete function systems, such as a Taylor expansion. The basic principles for constructing the freeform profiles using a Taylor expansion are explained below.

[0050] The freeform surface, when explicitly represented in the form z(x,y), can be described by a polynomial that, in a coordinate x perpendicular to the direction of motion of the optical components 11, 13, contains only even powers of x, and in a coordinate y parallel to the direction of motion, contains only odd powers of y. The freeform surface z(x,y) can initially be described generally, for example, by a polynomial expansion of the form z=∑m,n=1∞Cm,nxmyn described, where C m,nThis represents the expansion coefficient of the polynomial expansion of the freeform surface in order m with respect to the x-direction and order n with respect to the y-direction. Here, x, y, and z denote the three Cartesian coordinates of a point lying on the surface in the local area-related coordinate system. The coordinates x and y are to be inserted into the formula as dimensionless measurements in so-called lens units. Lens units means that all lengths are initially given as dimensionless numbers and subsequently interpreted in such a way that they are consistently multiplied by the same unit of measurement (nm, µm, mm, m). The reason for this is that geometric optics is scale-invariant and, unlike wave optics, does not have a natural unit of length.

[0051] A pure defocusing effect can be achieved according to Alvarez's theory if the freeform surface of the optical components 11, 13 can be described by the following 3rd order polynomial: z(x,y)=K⋅(x2⋅y+y33)

[0052] It is assumed here that the lateral displacement of the optical components 11, 13 occurs along the y-axis, which is defined by the equation. If the displacement is to occur along the x-axis, the roles of x and y in the above equation must be reversed accordingly. The parameter K essentially scales the profile depth and thus determines the achievable change in refractive power per unit of lateral displacement s.

[0053] For beams incident parallel to the optical axis OA and air (refractive index n = 1) between the two optical components 11, 13, the lateral displacement of the optical components by a distance s = |±y| causes a change in the wavefront according to the equation: ΔW(x,y)=K⋅(2⋅s⋅(x2+y2)+2⋅s33) This involves a change in focus position through a change in the parabolic wavefront component plus a so-called piston term (Zernike polynomial with j=1, n=0 and m=0), where the latter corresponds to a constant phase and does not affect the imaging properties if and only if the optical element according to the invention is located in the infinity beam path, i.e., in the region of a collimated beam. Otherwise, the piston term can usually be neglected with regard to the imaging properties.

[0054] The refractive power of such a wavefront manipulator functioning as a varifocal lens is given by the following formula: Φv=4⋅K⋅s(n−1)

[0055] Here, s is the lateral displacement path of an element along the y-direction, K is the scaling factor of the profile depth, and n is the refractive index of the material from which the lens is formed at the respective wavelength.

[0056] To minimize the element's center thickness, a term proportional to y (wedge or tilt term) can be added. Its optical effect on the two freeform surfaces then almost cancels itself out, but still allows for a minimization of the element's center thickness. A pure tilt term on the freeform surfaces is, to a first approximation, optically ineffective and therefore does not cause any color aberrations.

[0057] It is possible that the two optical components 11, 13, moving relative to each other, behave as in Fig. Figure 1 shows the optical components 11 and 13 oriented so that the two freeform surfaces 15 and 17 face each other. In this case, adjusting the zero position is particularly easy, namely by reducing the distance between the two optical components 11 and 13 until they touch. In this position, the optical components are automatically centered. The distance can then be increased axially just enough so that the two optical components 11 and 13 do not touch during lateral movement during normal operation. Alternatively, it is also possible to orient the two optical components 11 and 13 so that the freeform surfaces 15 and 17 face away from each other.

[0058] It is also possible that the freeform surfaces may contain additional higher-order terms to influence individual image defects. For example, a term of the form z(x,y)=K⋅(y⋅x4+23⋅(x2⋅y3)+y55) This primarily affects the primary spherical aberration and could therefore help correct spherical aberration that occurs when focusing to a different sample depth, for example in microscopy applications. Partial or complete compensation of spherical aberration caused by changes in the thickness of the element (piston term) in the convergent beam path can also be achieved in this way.

[0059] The structural profiles can be freely superimposed, i.e., a structure for changing the refractive power and a structure for changing the spherical aberration can be superimposed in a freeform surface 15, 17, so that a corresponding wavelength manipulator, when the optical components 11, 13 are shifted relative to each other, varies a refractive power effect and simultaneously changes a spherical aberration, with both changes being proportional to each other by an arbitrarily but fixedly preselectable proportionality factor.

[0060] Furthermore, it is also possible that both sides of the moving optical components 11, 13 exhibit an effective shape according to the forms described above. For example, a symmetrical division of the surface profile according to the formula above onto the front and back surfaces of a component could ensure that the profile depths on each surface remain sufficiently small, thus facilitating, for example, photolithographic fabrication of the elements, which typically only allows maximum profile depths in the range of < 10–30 µm. In addition to simplified fabrication, smaller profile depths also offer the advantage of causing fewer undesirable image aberrations compared to larger profile depths.Undesired image aberrations arise at the profiles of the optical components of a freeform element due to the finite distance between them. This means that a beam refracted at the freeform surface of the first optical component at a specific distance from the optical axis does not strike the second freeform surface at the exact corresponding point, but rather slightly offset. The resulting aberrations increase dramatically (superlinearly) with the profile depth, because greater profile depths not only have a greater refractive power but also require a greater distance between the elements. Therefore, splitting the freeform profiles onto the front and back of the freeform elements is always advantageous from an optical standpoint, even if it is more complex to manufacture.

[0061] According to Lohmann (cf. Appl. Opt. Vol. 9, No. 7, (1970), p. 1669-1671), it is possible to represent a variolens largely equivalent to the theory of Alvarez, in which two freeform surfaces are, for example, in the lowest order by an equation of the form z(x,y)=A⋅(x3+y3) The relative motion of the optical components 11 and 13 to each other is described as occurring along a straight line perpendicular to the optical system axis, running at an angle of 45° to the x- and y-axes. The constant A is a free scaling constant that describes the maximum profile depth of the freeform surface and thus the change in refractive power per unit path length. Lohmann's description is not an independent solution, but essentially only an alternative representation.

[0062] Further details regarding the construction of the freeform surfaces 15, 17, which enable the variable refractive effect, are described in US 3,305,294. Reference is made to this document regarding the construction of the freeform surfaces.

[0063] The wavefront manipulator described so far can correct monochromatic image aberrations at a specific wavelength by canceling out an existing aberration with a specifically induced, counteracting aberration. However, it is also possible to design the wavefront manipulator to correct not only monochromatic but also chromatic aberrations. A wavefront manipulator capable of correcting chromatic aberrations is described in Fig. 2 shown.

[0064] Before on the in Fig. In addition to the wavefront manipulator shown in Figure 2, the conditions for dichromacy, trichromacy and for the correction of the secondary spectrum are briefly described.

[0065] The condition for achromatism of a varifocal lens made of any number of elements is: ∑j=1kφjvj(λ1,λ2)=0

[0066] Here, φ denotes j the refractive power of the j-th lens and v j (λ1, λ2) the Abbe number of the medium from which the lens is formed, with reference to the collateral wavelengths λ1, λ, defined by: v(λ1,λ2)=n(λ0)−1n(λ2)−n(λ1)

[0067] If at the same time a predetermined system refractive power Φ ges Furthermore, the following additional condition must be met to achieve this: ∑j=1kφj=ϕges

[0068] In a dichromatically (“achromatically”) corrected lens, the refractive power is exactly the same at the two wavelengths λ1 and λ2. In this case, the primary longitudinal chromatic aberration is said to disappear. However, at all other wavelengths, especially the middle wavelength, λ0, it still deviates. This deviation is called the “secondary spectrum” of the longitudinal chromatic aberration.

[0069] The above argument can be directly applied, in a similar manner, to other wavefront effects of the wavefront manipulator element. The dichromacy condition remains exactly the same, and the second equation (constant refractive power) is replaced by an analogous equation that establishes a requirement (constraint) for the overall system effect on the desired wavefront error (e.g., spherical aberration).

[0070] To correct the secondary spectrum, the so-called partial dispersion coefficient P of a medium at the reference wavelength λ0 and the secondary wavelengths λ1 and λ2 is defined as follows: Pλ0,λ1,λ2=n(λ0)−n(λ1)n(λ2)−n(λ1)

[0071] The condition for the disappearance of the secondary spectrum at λ0 is explicitly stated: ∑j=1kφjvj⋅Pj,λ0,λ1,λ2=0

[0072] This additional condition can only be met if at least one medium has a partial dispersion coefficient P that deviates significantly from the so-called normal line.

[0073] It turns out that, for example, organic immersion oils deviate significantly from the normal line of the dispersion relation known for optical glasses. Consequently, a variable lens or a wavefront manipulator according to the invention can be designed such that the secondary spectrum vanishes. More explicitly, this means that, if the above condition is met, the wavefront effect of the wavefront manipulator according to the invention can exhibit an exactly identical (predefined) effect at three wavelengths λ0, λ1, and λ2. In the case of a trichromatic lens ("apochromatic lens"), the wavefront effect of a wavefront manipulator according to the invention is, in generalization of the above conditions, exactly the same at precisely three wavelengths λ0, λ1, and λ2. The explicit condition for trichromatism in a system with at least three independently adjustable refractive powers and media can be found in standard textbooks.

[0074] The in Fig. The wavefront manipulator shown in Figure 2 comprises two optical components 21, 23 arranged one behind the other along an optical axis OA and laterally displaceable relative to each other, i.e., perpendicular to the optical axis OA, as indicated in the figure by the arrows in the -y and +y directions. In this wavefront manipulator, each of the two optical components 21, 23 has a refractive freeform surface 25, 27 on one side and a planar surface 24, 26 on the side facing away from the freeform surface. The optical components 21, 23 are arranged relative to each other such that their freeform surfaces 25, 27 are opposite each other. The freeform surfaces 25, 27 are exactly complementary to each other in a zero position, so that the two optical components 21, 23 are equivalent to a plane-parallel plate in a zero position.

[0075] Between the two optical elements 21, 23 is an immersion medium 22, which in the Fig. The wavefront manipulator shown in Figure 2 can contain a liquid such as highly purified water, a saline solution, immersion oil, etc. To retain the liquid in the space between the two optical components 21, 23, the circumferential surface of the wavefront manipulator is provided with an elastic cuff 28. This cuff prevents leakage of the liquid immersion medium 22 and maintains a tight seal even during lateral movement of the optical components 21, 23 relative to each other. The cuff 28 can be formed, for example, from a plastic film or, in particular, an elastic sealing ring, which may be made of highly elastic rubber. However, instead of a cuff made of elastic material, another liquid-tight seal can also be used, for example, in the form of a bellows construction.Since the lateral movement of the optical components 21, 23 is in many cases only fractions of a millimeter, a variety of common liquid-tight seals are generally applicable. As a further alternative, the surfaces to be wetted by the immersion fluid can be coated with an adhesive layer that holds a thin immersion film between the freeform surfaces by means of adhesive forces, thus preventing leakage of the immersion fluid.

[0076] The optical components 21 and 23 themselves can be made of glass, plastic, or crystalline material, for example. The choice of material can depend particularly on the intended application of the wavefront manipulator. If it is to be used in the optical spectral range, glass or plastic will generally be chosen. If, on the other hand, it is to be used in the ultraviolet spectral range, the optical components 21 and 23 will typically be made of quartz glass or a crystalline material, such as calcium fluoride or barium fluoride. For the immersion fluid in the ultraviolet spectral range, highly purified water, for example, is a suitable option.

[0077] The following describes the adaptation of the immersion medium 22 to the material of the optical components 21, 23 using two specific examples. First, an adaptation for providing an achromatic varifocal lens is described, followed by an adaptation for providing a defined setting of the longitudinal chromatic aberration without changing the focus position.

[0078] For the provision of an achromatic varifocal lens, the condition for the adaptation of the immersion medium 22 to the material of the optical components 21, 23 in the wavefront manipulator can be derived as follows:

[0079] The two optical components 21, 23 moving relative to each other form a refractive power Φ1 =4·k·s-(n1-1) and the variable “immersion medium lens” between the plates forms a refractive power -Φ2=4·k·s·(n2-1), where k is the scaling factor of the freeform profile function, s is the displacement of the elements and n1 and n2 are the refractive indices of the material of the optical components 21, 23 and of the immersion medium 22 respectively at a mean wavelength of the considered spectral range.

[0080] The condition for achromatopsia in two closely spaced lenses is generally: Φ1ν1+Φ2ν2=0

[0081] Here, v1 and v2 denote the Abbe number of the material of the optical components 21, 23 and the Abbe number of the immersion medium 22, respectively. By substituting the equations for the refractive powers Φ1 and Φ2 into equation (7), the following condition can be established for the achromatic varifocal lens: n1−1ν1−n2−1ν2=0

[0082] Of course, due to the limited selection of available optical materials, especially when considering specific requirements such as aging resistance, thermal expansion, etc., slight deviations from the above condition are possible in practice without departing from the scope of the invention. A parameter range for a varifocal lens can be characterized approximately by the following conditions: |n1−1ν1−n2−1ν2|<0.05

[0083] Ideally, the following should even apply: |n1−1ν1−n2−1ν2|<0.01

[0084] And even more preferentially, the following may apply: |n1−1ν1−n2−1ν2|<0.001

[0085] An achromatic wavefront manipulator that is intended to influence a specific Zernike term instead of defocusing must also satisfy the same achromatization condition (7) or (8a) to (8c).

[0086] An element that provides, for example, a certain amount of spherical aberration independent of wavelength could be provided by two optical components whose freeform surfaces 25, 27 have the following shape z(x,y)=k⋅(y⋅x4+23⋅(x2⋅y3)+y53) and which are formed from a glass which, together with the immersion medium, fulfills condition (7) or (8a) to (8c).

[0087] The achromatization condition also applies analogously in all other cases where an "arbitrary" wavefront change ΔW(x,y) is generated at a fundamental wavelength by designing the freeform profile function z(x,y) to be proportional to the antiderivative of ΔW(x, y) in the direction of the movement of the optical components relative to each other and proportional to the function ΔW(x, y) itself perpendicular to the direction of movement.

[0088] With a wavefront manipulator that incorporates an immersion medium between the optical components, longitudinal chromatic aberration can not only be selectively reduced to zero, but the wavefront manipulator can also be designed to generate defined amounts of longitudinal chromatic aberration, depending on the choice of optical media. If the condition specified in equation (8a), equation (8b), or equation (8c) is not met, a lateral shift of the optical components 21, 23 according to equation (2) simultaneously causes a change in refractive power at the mean wavelength (i.e., a defocus) and, relative to this, a longitudinal chromatic aberration for the marginal or secondary wavelengths. The greater the deviation from the condition specified in equation (8a), equation (8b), or equation (8c), the more pronounced this effect becomes. It is particularly noticeable when equation (8a) is not satisfied.

[0089] In individual cases, such superposition could be useful, for example, if the defocus at the mean wavelength can be compensated for by other optical means. Generally, however, a clear separation between a change in the mean focus position and a change in the longitudinal chromatic aberration is desirable. For this case, the solution proposed here is to use materials and media for the optical components 21, 23 and the immersion medium 22 arranged between them that differ almost exactly in their refractive index n at the mean wavelength, but significantly in their Abbe number v, in particular materials and media where the conditions are simultaneously |n1−n2|≤0.05 and |ν1−ν2|≥5 are met. If a larger change in longitudinal chromatic aberration is desired without changing the focus position, these conditions should be defined more precisely, namely |n1−n2|≤0.01 and |ν1−ν2|≥10 or even |n1−n2|≤0.002 and |ν1−ν2|≥15

[0090] Suitable material combinations can be found and are even widely used, since the dispersion of organic hydrocarbons at typical refractive indices of glass is consistently significantly higher than that of glass. If the optical components 21, 23 are made of plastic, an aqueous (salt) solution doped with suitable alkali ions, for example, can be used as the immersion medium 22.

[0091] Conditions (9a) to (9c) can be understood from the following consideration: The greater the difference between the Abbe number of the optical components 21, 23 and the Abbe number of the immersion medium 22, the smaller the lateral displacement paths can be—and the flatter the freeform surfaces 25, 27 of the optical components 21, 23 can be to achieve a predetermined longitudinal chromatic aberration by the wavefront manipulator. Conversely, the less the refractive index of the optical components 21, 23 differs from the refractive index of the immersion medium 22, the smaller the change in focus position at the mean wavelength when setting a predetermined longitudinal chromatic aberration.

[0092] According to the design principle expressed in equations (8a) to (8c), for example, a wavefront manipulator for influencing the so-called Gaussian error, i.e., the image error that describes the chromatic variation of the spherical aberration, can be provided using two optical components 21, 23, whose freeform surfaces are given by equation (5).

[0093] As already mentioned, several structural profiles can be freely superimposed in the freeform surfaces 25, 27 of the optical components 21, 23. For example, a structure for changing the refractive power and a structure for changing the spherical aberration can be superimposed in the freeform surfaces 25, 27, so that a corresponding varifocal lens, when the optical components 21, 23 are shifted relative to each other, varies the refractive power effect and simultaneously changes the spherical aberration, with both changes being proportional to each other by an arbitrarily but fixedly preselected proportionality factor. The rules outlined above regarding the effect of a corresponding material selection according to conditions (8a), (8b) or (8c) or according to conditions (9a), (9b) or (9c) can also be applied analogously in such more general applications.

[0094] A wavefront manipulator, as it is called in relation to Fig. 2, as described above, can be found in Fig. 1 in place of the one referring to Fig. 1 wavefront manipulator described above.

[0095] A second embodiment of the microscope objective according to the invention is shown schematically in Fig. Figure 3 illustrates this. The microscope objective 100 of the second embodiment, which, like the microscope objective of the first embodiment, is designed as an adaptive microscope objective, differs from the microscope objective 1 of the first embodiment essentially in that the first lens unit 103 and the second lens unit 105 each consist of a lens group. Another difference is that the aperture diaphragm 107 is positioned upstream of the wavefront manipulator 109 towards the object-side first lens unit 103 instead of being downstream of it towards the image-side lens unit 105. But even in the version shown in Fig. In the arrangement of the aperture diaphragm 107 shown in Figure 3, it is advantageous if the diaphragm is arranged as close as possible to the wavefront manipulator 109. The wavefront manipulator 9 itself does not differ from the wavefront manipulator 9 of the first embodiment. As in the first embodiment (and in all other embodiments), a wavefront manipulator such as the one described with reference to Figure 3 can also be used instead of the wavefront manipulator shown in Figure 3. Fig. 2 has been described, especially when chromatic image errors are to be corrected.

[0096] In the microscope objective 100 of the second embodiment, the first lens unit 103 comprises at least two lenses 111, 113, one of which is an aspherical lens. In the present embodiment, the lens 103 closest to the wavefront manipulator 109 is an aspherical lens.

[0097] The second lens unit 105 of the microscope objective 100 of the second embodiment comprises three lenses 115, 117, 119 and is designed as an afocal lens group, i.e., an incident collimated beam of light generates an outgoing collimated beam of light, possibly with a different beam diameter. For this purpose, in the embodiment, the two outer lenses 115, 119 of the lens group 105 are designed as positive lenses and the middle lens 117 as a negative lens. In contrast to the afocal three-lens lens group shown in the embodiment, the second lens unit 105 can also have more than three lenses. In particular, each of the three lenses in Fig. The lenses 115, 117, and 119 shown in the diagram can be configured as a lens group. However, it is also possible to use only one or two of the lenses shown in the diagram. Fig. The lens group of the second lens element 105 shown in section 3 is itself composed of lens groups.

[0098] The design of the second lens unit 105 as an afocal lens group makes it possible to combine the microscope objective 100 with various other optical units, in particular with various microscope tubes.

[0099] It is noted that lens groups 103 and 105 in Fig. 3 are highly schematically represented, and the actual lens groups are usually more complex than in the schematic representation of the Fig. 3 are set up.

[0100] A third embodiment of a microscope objective according to the invention is described in Fig. Figure 4 illustrates the third embodiment of the microscope objective 200, which is also designed as an adaptive microscope objective. It differs from the first embodiment primarily in that it includes two wavefront manipulators 209 and 219. The first lens unit 203 and the second lens unit 205 are shown as individual lenses, as in the first embodiment. However, it is also possible to implement the first lens unit 203 and / or the second lens unit 205 as a lens group or groups, as in the second embodiment. It should be noted that, in principle, it is also possible in the second embodiment to replace one of the two lens groups 103 and 105 with a single lens.

[0101] In the microscope objective 200 of the second embodiment, the aperture diaphragm 207 is located between the two wavefront manipulators 209 and 219. However, it could also be arranged directly in front of the object-side wavefront manipulator 209 or directly behind the image-side wavefront manipulator 219. With the aid of the two wavefront manipulators, two different image aberrations can be corrected independently of each other by inducing opposing image aberrations. If the wavefront manipulators 209 and 219 are arranged as described in the following diagram: Fig. As described in section 1, two monochromatic image errors can be corrected if they are as described in relation to Fig. As described in section 2, the image aberrations can also be corrected achromatically. It is also fundamentally possible to use one of the two wavefront manipulators as described in section 2. Fig. 1 to form and one of the two wavefront manipulators as shown in Fig. Figure 2 illustrates this. Furthermore, it is possible to arrange more than two wavefront manipulators in the adaptive microscope objective, thereby further increasing the number of correctable image aberrations. Each wavefront manipulator is configured as described in Figure 2. Fig. 1 described, can be trained, or how with reference to Fig. 2 described.

[0102] The in Fig. The schematically illustrated embodiment 4 enables two independently adjustable wavefront manipulations. This can be used to simultaneously compensate for changes in two influencing factors, for example, to compensate for a displacement of the object position, typically by ±200 µm (= ±400 RE), and a change in the refractive index of an immersion medium used with the microscope objective. The refractive index typically fluctuates in the range of 1.30 to 1.38. The latter represents the usual range in which the refractive index of aqueous solutions can change with slightly different salt concentrations and temperatures. With the adjustable wavefront manipulators 209, 219 from Fig. 4. Changes in the two influencing variables can be compensated independently. With a constant first influencing variable, a change in the second influencing variable can be compensated simply by adjusting the wavefront manipulator assigned to the second influencing variable, and vice versa. The adjustment range in the wavefront manipulator required to compensate for one influencing variable depends on the value of the second influencing variable.

[0103] For example, the adjustment range required to compensate for a shift in the object's position depends on the refractive index of the immersion medium, and vice versa. Generally, and especially when more than two influencing variables need to be compensated, a parametric model can be created. This model, running on a computing unit connected to the wavefront manipulator(s), determines the necessary control variables and outputs them to the wavefront manipulator(s). Alternatively, lookup tables stored in a control unit connected to the wavefront manipulator(s) can be used. These lookup tables contain the required adjustment ranges for compensating for changes in the influencing variable(s).The adjustment paths of the wavefront manipulator(s) required to compensate for the change in the influencing variable(s) can be determined in practice by an optimization calculation in an optical design program or by calibration measurements, which provides even more accurate results than an optimization calculation.

[0104] Specific embodiments of microscope objectives according to the invention are described below. These are each designed as adaptive microscope objectives.

[0105] As a first concrete embodiment of an optical system with a microscope objective according to the invention, the following is described using the Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11 to Fig. 12 describes a microscope with a high-aperture microscope objective. The microscope objective is an immersion objective designed according to the invention with a numerical aperture of 1.0 for water immersion, with an associated wavefront manipulator designed for refocusing at sample depths of up to ± 200 Rayleigh units (RE) in physiological saline solution (typical for the refractive index of cell fluids). The refocusing range of ± 200 RE within the sample medium corresponds to an adjustment range of ± 100 µm at a mean reference wavelength of 546 nm. The microscope objective has an object-side image field with a diameter of 1.0 mm. It also features a correction that is diffraction-limited throughout the entire adjustment range of ± 200 RE.

[0106] The microscope of the first embodiment is in Fig. Figure 5 is shown schematically. It comprises a microscope objective 41, which consists of a plurality of objective lenses and which converts a divergent beam of rays emanating from an observation object 40 into a collimated beam of rays, as well as a tube lens system 43 downstream of the microscope objective 41, which comprises two achromatic lenses. By means of the tube lens system 43, the collimated beam of rays is focused in the image plane 45.

[0107] The microscope objective 41 comprises, in the direction from the object 40 to the image, a first lens assembly 47, hereinafter referred to as the front positive lens group, which has such a positive refractive power that it transforms a divergent beam of rays emanating from the observation object 40 into a collimated beam of rays. A further lens group 49 with positive refractive power, hereinafter referred to as the middle positive lens group, is arranged downstream of the front positive lens group 47. This lens group converges the collimated beam of rays emanating from the first positive lens group 47. A concave lens 51 is arranged downstream of the middle positive lens group 49. This concave lens group transforms the convergent beam of rays emanating from the middle positive lens group into a divergent beam of rays.The concave lens 51 is followed by another lens group 53 with positive refractive power, hereinafter referred to as the rear positive lens group, which generates a collimated beam of light from the divergent beam emanating from the concave lens 51. The rear positive lens group is the final lens group of the microscope objective 41.

[0108] In the present first concrete embodiment, the first lens combination 47 is designed telecentrically on the object side, with its telecentricity error being 0.34°.

[0109] Table 1 below indicates how well the sine condition is fulfilled for the front positive lens group 47 in the present specific embodiment. NAO = n0 · sinσ0 is the numerical aperture in object space, and σ0 is the angle of inclination of the marginal ray to the optical axis OA. fFG=−n0⋅fFG' The front (object-side) focal length of the front lens group, n0 the refractive index of the immersion medium between the object and the front lens, and h1 the incidence height of the aperture beam. As can be seen, the condition is approximately fulfilled. The deviations can also be partly explained by the fact that the condition of a collimated beam path at the wavefront manipulator is not entirely strictly adhered to. Taking this into account, the agreement of h1 and f must be considered. FG · sinσ0 can be considered very good and therefore significant. Table 1 NAO fFG' / mm f FG / mm σ0 / Grad h1 / mm f FG · sin σ0 0.1 12.785 17.080 4.291 1.272 1.278 0.2 12.785 17.080 8.607 2.552 2.556 0.3 12.785 17.080 12.973 3.848 3.834 0.4 12.785 17.080 17.417 5.169 5.113 0.5 12.785 17.080 21.973 6.527 6.391 0.6 12.785 17.080 26.680 7.934 7.669 0.7 12.785 17.080 31.591 9.411 8.948 0.8 12.785 17.080 36.777 10.984 10.226 0.9 12.785 17.080 42.342 12.698 11.505 1.0 12.785 17.080 48.454 14.642 12.783

[0110] Between the front positive lens group 47 and the middle positive lens group 49 is an air space containing the collimated beam of light emanating from the front positive lens group 47. A wavefront manipulator 57 is arranged in this air space. This manipulator comprises two optical components 59 and 61, which are arranged to be laterally displaceable perpendicular to the optical axis OA and in opposite directions relative to each other. The freeform profiles of the optical components 59 and 61 of the wavefront manipulator 57 are designed such that a displacement of the optical components 59 and 61 in opposite directions perpendicular to the optical axis OA by the same amount of displacement results in a variation of the defocus. A system pupil, i.e., a real image of an aperture diaphragm, is also located in the area of ​​the wavefront manipulator.

[0111] The wavefront manipulator 57 allows a lateral displacement of its optical components 59, 61 perpendicular to the optical axis by up to ± 2.5 mm each, whereby the movement of the two optical components 59, 61 is always exactly opposite to each other, so that the relative movement between the two optical components 59, 61 is up to 5 mm. The lateral displacement of the optical components 59, 61 by up to ± 2.5 mm each enables a variation of the object focal length of up to ± 100 µm around the mean object focal length. It should be noted, however, that the variation of the object focal length by ± 100 µm does not represent the limit of what is possible. Rather, significantly larger effects of the wavefront manipulator are also achievable.

[0112] In the collimated beam between the front positive lens group 47 and the middle positive lens group 49, the inclination angles of the marginal rays with respect to the optical axis OA are less than 2°. Over the adjustment range of the optical components of ± 2.5 mm each, the inclination angles of the marginal rays vary between 1.65° and 1.05°. For non-axis-parallel beams, half the angle between the coma rays (boundary rays of the beams) can be considered instead of the marginal ray inclination angle with respect to the system axis.

[0113] The microscope's design data from Fig. 5 are presented in tabular form in Fig. 9 shown, where the in Fig. The 5 areas shown in the table are numbered from left to right.

[0114] Besides the wavefront manipulator, the microscope objective consists exclusively of spherical lenses, the surface of which is described by the usual vertex form of the sphere equation: z=(x2+y2) / R1+1−(1+k)⋅(x2+y2)R2

[0115] The wavefront manipulator comprises exactly two freeform surfaces, whose shape is generally described by a polynomial expansion according to equation (1). The polynomial coefficients of the two identical freeform surfaces (surface numbers 14 and 18 in Fig. 9) are: X2Y: -5,6320E-05 Y3: -1,8852E-05 X4Y: 1,4094E-08 X2Y3: 9,3457E-09 Y5: 2,7650E-09 X6Y: 3,2102E-11 X4Y3: 3,3091 E-11 X2Y5: 1,9355E-11 Y7: 4,6200E-12

[0116] The refractive indices of the optical media at the wavelengths considered for design are: REFRACTIVE INDICESGLASS CODE 830.00 643.85 546.07 480.00 435.00 404.00 ‚NACL0923‘ 1.329121 1.332899 1.335953 1.338964 1.341788 1.3194314 NK5 SCHOTT 1.515478 1.520241 1.524583 1.529098 1.533470 1.537439 SYGH51_OHARA 1.743583 1.751319 1.758437 1.765879 1.773113 1.779701 SFPL53_OHARA 1.435019 1.437560 1.439854 1.4422 1.444472 1.446499 NKZFS11_SCHOTT 1. 626065 1.633952 1.641325 1.649149 1.656873 1.664018 SNBH53_OHARA 1.721115 1.732356 1.743413 1.755560 1.767954 1.779800 NLASF44_SCHOTT 1.790816 1.799830 1.808316 1.817304 1.826131 1.834245 NSK2 _SCHOTT 1.598950 1.604651 1.609937 1.615470 1.620846 1.625736 NBAK4_SCHOTT 1.560804 1.566238 1.5712 49 1.576493 1.581598 1.586255 NSF1_SCHOTT 1.699812 1.711443 1.723077 1.736046 1.749488 1.762557 SFTM16_OHARA 1.550287 1.588563 1.596670 1.605592 1.614743 1.623555 NBK7_SCHOTT 1.510202 1.514719 1.518722 1.522829 1.526769 1.530324

[0117] The In the Fig. 6, Fig. 7 to Fig. Figure 8 shows the microscope objective 41 with the optical components 59, 61 of the wavefront manipulator 57 in three different relative positions, wherein the in Fig. The relative position shown in Figure 7 is the neutral position, in which the wavefront manipulator 57 does not induce any defocus. In this position, the mean vertex distance between the front lens and the object point is 2.0 mm, so that the microscope objective has a focal length of 2.0 mm. The in Fig. The relative position of the optical components 59, 61 shown in Figure 6 corresponds to a reduction in the object focal length from 2.0 mm to 1.9 mm, and the in Fig. The position shown in Figure 8 corresponds to an increased object section width from 2.0 mm to 2.1 mm. Since the vertex distance lies in the medium "NaCl0923" (physiological saline solution), this corresponds either to a change in the focusing depth in the sample (cell) or to a change in the thickness of the immersion film between the coverslip (made of NK5) and the vertex of the object-side front lens of the anterior positive lens group 47.

[0118] The Fig. 10, Fig. 11 to Fig. 12 show the ones in the Fig. 6, Fig. 7 to Fig. The 8 positions of the wavefront manipulator 57 depict the image aberrations occurring for wavelengths in the range between 404 and 830 nm. The vertical axis denotes the geometric-optical transverse aberration, with the scale ranging from -0.5 mm to +0.5 mm. The left side, labeled Y-Fan in the figure, shows the transverse aberration for a beam of light as a function of the y-coordinate of the aperture beam at the exit pupil, while the right side, labeled Y-Fan, shows the y-coordinate of the aperture beam at the exit pupil. Fig. The X-fan (X-fan) is a corresponding representation of the lateral aberration for the beam of light as a function of the x-coordinate of the aperture beam at the exit pupil. The beam of light has an axial ray as its principal ray; that is, the principal ray is a ray that runs along the optical axis of the microscope objective 41, thus having x and y coordinates of 0,0 and an angle of incidence of 0° with respect to the optical axis in both the yz and xz planes. The optical system... Fig. The 5th pixel produced by a beam of rays designated by an axial ray as the principal ray lies on the optical axis. In the Fig. 10, Fig. 11 to Fig. 12 shows Fig. 10. The image errors for the wavefront manipulator setting are from Fig. 6, Fig. 11 the image errors for the wavefront manipulator setting from Fig. 7 and Fig. 12 the image errors for the wavefront manipulator setting from Fig. 8. It is readily apparent to a person skilled in the art that the microscope objective 41 provides a practically diffraction-limited image over the entire adjustment range of the wavefront manipulator 57.

[0119] To further illustrate, the Fig. 13, Fig. 14 to Fig. 15, which typical wavefront errors would arise if a comparably well-corrected microscope objective without the wavefront manipulator 57 were used for imaging with an equally varying object focal length of ±100µm and pure refocusing (compensation for the defocus, but without compensation of the resulting orders of spherical aberration) were carried out using the tube lens spacing.

[0120] As a second concrete embodiment of an optical system with a microscope objective according to the invention, a microscope with a very high aperture microscope objective (NA = 1.2) is described below.

[0121] The microscope objective is an immersion objective designed according to the invention for water immersion and an object-side numerical aperture of NAO = 1.2 with an associated wavefront manipulator. The refocusing range within the sample medium is up to ± 50 µm, which corresponds to an adjustment range of ± 132 RE at a mean reference wavelength of 546 nm. The microscope objective has a 40x magnification and an object-side field of view of 0.622 mm in diameter and is essentially diffraction-limited corrected over the entire depth adjustment range.

[0122] The microscope of the second embodiment is in Fig. Figure 5 is shown schematically. It comprises a microscope objective 141, which consists of a plurality of objective lenses and which converts a divergent beam of rays emanating from an observation object 140 into a collimated beam of rays, as well as a tube lens system 143 arranged downstream of the microscope objective 141, which focuses the collimated beam of rays in the image plane 145. In contrast to the tube lens system 43 of the microscope from Fig. 5 In the present embodiment, the tube lens system 143 consists of only a single lens.

[0123] The microscope objective 141 comprises, in the direction from the object 140 to the image, a first lens assembly 147, hereinafter referred to as the front positive lens group, which has such a positive refractive power that it transforms a divergent beam of rays emanating from the observation object 140 into a collimated beam of rays. A further lens group 149 with positive refractive power, hereinafter referred to as the middle positive lens group, is arranged downstream of the front positive lens group 147. This lens group converges the collimated beam of rays emanating from the first positive lens group 147. A concave lens 151 is arranged downstream of the middle positive lens group 149. This concave lens group transforms the convergent beam of rays emanating from the middle positive lens group 149 into a divergent beam of rays.The concave lens 151 is followed by another lens group 153 with positive refractive power, hereinafter referred to as the rear positive lens group, which generates a collimated beam of light from the divergent beam emanating from the concave lens 151. The rear positive lens group is the final lens group of the microscope objective 141.

[0124] In the present second concrete embodiment, the first lens combination 147 is designed telecentrically on the object side, with its telecentricity error being 0.77°.

[0125] Table 2 below indicates how well the sine condition is fulfilled for the front positive lens group 47 in the present specific embodiment. NAO = n0 · sinσ0 is the numerical aperture in object space, and σ0 is the angle of inclination of the marginal ray to the optical axis OA. fFG=−n0⋅fFG' The front (object-side) focal length of the front lens group, n0 the refractive index of the immersion medium between the object and the front lens, and h1 the incidence height of the aperture beam. As can be seen, the condition is approximately fulfilled. The deviations can also be partly explained by the fact that the condition of a collimated beam path at the wavefront manipulator is not entirely strictly adhered to. Taking this into account, the agreement of h1 and f must be considered. FG - sinσ0 can be considered very good and therefore significant. Table 2 NAO fFG' / mm f FG / mm σ0 / Grad h1 / mm f FG · sin σ0 0.1 6.870 9.165 4.298 0.673 0.687 0.2 6.870 9.165 8.621 1.348 1.374 0.3 6.870 9.165 12.994 2.026 2.061 0.4 6.870 9.165 17.446 2.711 2.748 0.5 6.870 9.165 22.009 3.403 3.435 0.6 6.870 9.165 26.725 4.105 4.122 0.7 6.870 9.165 31.646 4.822 4.809 0.8 6.870 9.165 36.842 5.559 5.496 0.9 6.870 9.165 42.421 6.323 6.183 1.0 6.870 9.165 48.549 7.127 6.870 1.1 6.870 9.165 55.535 7.994 7.557 1.2 6.870 9.165 63.554 8.915 8.206

[0126] Between the front positive lens group 147 and the middle positive lens group 149 is an air space containing the collimated beam of light emanating from the front positive lens group 147. A wavefront manipulator 157 according to the invention is located in this air space. This manipulator comprises two optical components 159, 161, which are arranged to be laterally displaceable perpendicular to the optical axis OA and in opposite directions relative to each other. The freeform profiles of the optical components 159, 161 of the wavefront manipulator 157 are designed such that a displacement of the optical components 159, 161 perpendicular to the optical axis OA by the same amount of displacement results in a variation of the defocus. A system pupil, i.e., a real image of an aperture diaphragm, is also located in the region of the wavefront manipulator 157.

[0127] The wavefront manipulator 157 enables a lateral displacement of the optical components 159 and 161 perpendicular to the optical axis by up to ± 2.0 mm each, whereby the movement of the two optical components 159 and 161 is always exactly opposite to each other, so that the relative movement between the two optical components 159 and 161 is up to 4 mm. This lateral displacement of up to ± 2.0 mm allows for a variation of the object focal length of up to ± 50 µm around the mean object focal length. It should be noted, however, that a variation of ± 50 µm in the object focal length is not the limit of what is possible. Significantly larger effects of the wavefront manipulator are also achievable.

[0128] In the collimated beam between the front positive lens group 147 and the middle positive lens group 149, the inclination angles of the marginal rays with respect to the optical axis OA are less than 2°. Over the adjustment range of the optical components of ± 2.0 mm each, the inclination angles of the marginal rays vary between 0.20° and 1.31°. For non-axis-parallel beams, half the angle between the coma rays (boundary rays of the beams) can be considered instead of the marginal ray inclination angle with respect to the system axis.

[0129] The microscope's design data from Fig. 16 are listed in tabular form in Fig. 9 shown, where the in Fig. The 16 areas shown in the table are numbered from left to right.

[0130] In addition to the wavefront manipulator and spherical lenses, the microscope objective also features two aspherical surfaces, which are described by the usual vertex shape of a rotational asphere: z=(x2+y2) / R1+1−(1+k)⋅(x2+y2)R2+A⋅(x2+y2)2+B⋅(x2+y2)3+C⋅(x2+y2)4+D⋅(x2+y2)5 the two aspherical surfaces (surfaces 3 and 4 in the table of Fig. 20) exhibit the following aspheric coefficients: Area 3: A = -0,156746E-01 B = -0,119916E+00 C = 0,215754E+00 D = -0,204669E+00 Area 4: A = 0,127444E-02 B = 0,404391 E-04 C = 0,137145E-04 D = -0,1 03400E-05

[0131] The wavefront manipulator comprises exactly two freeform surfaces, whose shape is generally described by a polynomial expansion according to equation (1). The polynomial coefficients of the two identical freeform surfaces (surface numbers 14 and 18 in Fig. 20) are: X2Y: -1,2659E-04 Y3: -4,2124E-05 X4Y: -1,5024E-07 X2Y3: -9,7060E-08 Y5: -2,4566E-08 X6Y: -9,8928E-10 X4Y3: -8,7122E-10 X2Y5: -5,4991E-10 Y7: -1,4515E-10

[0132] The refractive indices of the optical media at the wavelengths considered for design are: GLASS CODE 850.00 643.85 546.07 479.99 435.83 404.00 365.00 ‚W23‘ 1.326855 1.331188 1.334190 1.337167 1.339939 1.342540 1.346757 K5_SCHOTT 1.515107 1.520241 1.524583 1.529099 1.533376 1.537439 1.544127 SLAH58_OHARA 1.865804 1.877573 1.888146 1.899492 1.910498 1.921170 1.939182 SFPL53_OHARA 1.434820 1.437560 1.439854 1.442215 1.444424 1.446499 1.449862 NKZFS2 SCHOTT 1.549486 1.555701 1.560824 1.566120 1.571136 1.575915 1.583828 NLASF44_SCHOTT 1.790134 1.799830 1.808316 1.817305 1.825940 1.834245 1.848126 NKZFS11_SCHOTT 1.625462 1.633952 1.641325 1.649150 1.656705 1.664018 1.676362 SNBH53_OHARA 1.720293 1.732356 1.743413 1.755563 1.767681 1.779800 1.801257 NKZFS4_SCHOTT 1.602051 1.609874 1.616639 1.623803 1.630709 1.637388 1.648656 SNBH52_OHARA 1.659038 1.668601 1.677185 1.686467 1.695574 1.704528 1.719980 SYGH51_OHARA 1.742985 1.751319 1.758437 1.765881 1.772957 1.779701 1.790832 NBALF4_SCHOTT 1.570691 1.576827 1.582122 1.587690 1.593010 1.598106 1.606583 NBK7_SCHOTT 1.509840 1.514719 1.518722 1.522829 1.526685 1.530324 1.536270

[0133] In the Fig. 17, Fig. 18 to Fig. Figure 19 shows the microscope objective 141 with the optical components 159, 161 of the wavefront manipulator 157 in three different relative positions, wherein the in Fig. The relative position shown in Figure 18 is the neutral position in which the wavefront manipulator 157 does not induce any defocus. The position shown in Figure 18 is the neutral position. Fig. The relative position of the optical components 159, 161 shown in 17 corresponds to a reduction of the object focal length by 50 µm and the in Fig. Position 19 shown corresponds to an increase in the object section width of 50 µm.

[0134] The Fig. 21, Fig. 22 to Fig. 23 show the ones in the Fig. 17, Fig. 18 to Fig. The 19 positions of the wavefront manipulator shown in Figure 57 exhibit image errors occurring for wavelengths in the range between 365 and 850 nm. As shown in the Fig. 10, Fig. 11 to Fig. Figure 12 denotes the geometric-optical lateral aberration, with a scale ranging from -0.5 mm to +0.5 mm. The left side, labeled Y-Fan in the figure, shows the lateral aberration for a beam of light as a function of the y-coordinate of the aperture ray at the exit pupil, while the right side, labeled in the Fig. The X-fan (X-fan) is a corresponding representation of the lateral aberration for the beam of light as a function of the x-coordinate of the aperture beam at the exit pupil. The beam of light has an axial ray as its principal ray; that is, the principal ray is a ray that runs along the optical axis of the microscope objective 141, thus having x and y coordinates of 0,0 and an angle of incidence of 0° with respect to the optical axis in both the yz and xz planes. The optical system... Fig. The 16th generated pixel of a beam of rays, characterized by an axial ray as the principal ray, lies on the optical axis. In the Fig. 21, Fig. 22 to Fig. 23 shows Fig. 21 the image errors for the wavefront manipulator setting from Fig. 17, Fig. 22 the image errors for the wavefront manipulator setting from Fig. 18 and Fig. 23 the image errors for the wavefront manipulator setting from Fig. 19. It is readily apparent to the person skilled in the art that the microscope objective 141 provides a practically diffraction-limited image over the entire adjustment range of the wavefront manipulator 157.

[0135] The present invention has been explained in more detail with reference to exemplary embodiments for illustrative purposes. However, the invention is not limited to the illustrated embodiments. Rather, features of the individual embodiments can also be combined with one another, provided that the features do not contradict each other. In addition, modifications of the individual embodiments can be made. The invention is therefore to be limited only by the appended claims. Examples of possible deviations from the exemplary embodiments are set out below: In the described embodiments, the optical components of the wavefront manipulator are shifted in the opposite direction in the y-direction, which corresponds in the figures to a shift perpendicular to the optical axis OA within the plane of the drawing. However, this is not mandatory. The direction of the shift can have any orientation in a plane perpendicular to the optical axis. For example, if a movement in the x-direction were chosen instead of the y-direction, the powers of x and y in the description of the freeform surface would have to be interchanged accordingly. With an arbitrary position of the shift axis relative to the system coordinate system, the coefficients for the perfectly congruent freeform surface would be formally completely different, so the coefficients must always be considered in conjunction with the chosen coordinate system.

[0136] The microscopes described in the specific embodiments were used with an immersion medium positioned between the specimen and the microscope objective. This medium has a significantly higher refractive index than air, thus enabling high numerical apertures of the microscope objectives. Common immersion media have refractive indices between 1.3 and 2.1, often ranging from approximately 1.3 to 1.5. The refractive index can fluctuate by up to 5% or more, for example, due to temperature variations.

[0137] In the exemplary embodiments, wavefront manipulators were used as pupil filters. However, instead of or in addition to a wavefront manipulator, at least one other pupil filter can also be used. Examples of suitable pupil filters are phase masks, such as ring-shaped phase plates, as used to implement the Zernike phase contrast method known to those skilled in the art. Further examples of suitable pupil filters are apodization filters, spectral filters, or spatial light modulators (SLM). The microscope objective according to the invention is advantageous in that it enables a quasi-modular design in conjunction with one or more pupil filters.

Claims

Microscope objective (1, 100, 200) with a first lens unit (3, 103, 203), at least one second lens unit (5, 105, 205) and a real pupil (7, 107, 207), wherein: - the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205) are arranged at a distance from each other along an optical axis (OA) of the objective, such that a space is provided between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205), and the second lens unit (5, 105, 205) is arranged image-side to the first lens unit (3, 103, 203); - the first lens unit (3, 103, 203) is configured such that it collimates a beam of light generated;- the real pupil (7, 107, 207) is located in the space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205), characterized in that it has a numerical aperture of at least 0.

8. Microscope objective (1, 100, 200) according to claim 1, in which the first lens unit (3, 103, 203) for that pupil region which is between 0% and 100% of the pupil radius, at least the condition | h 1 − f FG ⋅ sin σ 0 h 1 | ≤ 0.3, fulfilled, whereby h 1 the angle of incidence of the aperture beam at the location of the pupil, σ 0 the beam inclination angle of the edge beam relative to the optical axis, the object-side focal length of the first lens unit (3, 103, 203) in air and n 0 denote the refractive index of a medium adjacent to the object side of the first lens unit (3, 103, 203). Microscope objective (1, 100, 200) according to claim 2 in which the first lens unit (3, 103, 203) for that pupil region which is between 0 and 71% of the pupil radius, at least the condition: | h 1 − f FG ⋅ sin σ 0 h 1 | ≤ 0.15 fulfilled. Microscope objective (100) according to claim 1 or claim 2 or claim 3, in which the first lens unit (103) comprises an aspherical lens (113). Microscope objective (1, 100, 200) according to one of claims 1 to 4, in which the first lens unit (3, 103, 203) is designed telecentrically on the object side. Microscope objective (1, 100, 200) according to one of claims 1 to 5, in which at least one pupil filter (9, 19, 109, 203) is arranged in the space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205). Microscope objective (1, 100, 200) according to claim 6, in which at least one wavefront manipulator (9, 19, 109, 209, 219) is arranged as a pupil filter in the space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205), and the wavefront manipulator (9, 19, 109, 209, 219) comprises a first optical component (11, 21) with at least one refractive freeform surface (15, 25) or a diffractive surface and at least one second optical component (13, 23) with at least one refractive freeform surface (17, 27) or a diffractive surface, wherein the first optical component (11, 21) and the second optical component (13, 23) are arranged one after the other along the optical axis (OA). are arranged in a direction of movement perpendicular to the optical axis (OA) and are movable relative to each other. Microscope objective (1, 100, 200) according to claim 7, in which an immersion medium contacting the two components is located between the first optical component (21) and the second optical component (23) of the wavefront manipulator (19). Microscope objective (1, 100, 200) according to claim 8, in which the immersion medium is a liquid or an elastic optochet. Microscope objective (1, 100, 200) according to one of claims 8 or 9, in which the immersion medium has a dispersion profile that deviates from the normal line. Microscope objective (1, 100, 200) according to one of claims 8 to 10, in which the material of the first optical component (21) and the second optical component (23) of the wavefront manipulator (19) have a dispersion profile that deviates from the normal line. Microscope objective (1, 100, 200) according to one of claims 7 to 11, in which the real pupil is located between the first optical component (11, 21) and the second optical component (13, 23) of the wavefront manipulator (9, 19, 109, 209, 219). Microscope objective (1, 100, 200) according to one of claims 6 to 12, in which at least one of the following optical elements is arranged in the space between the first lens unit (3, 103, 203) and the second lens unit (5, 105, 205) as a pupil filter: a phase mask, an apodization filter, a spectral filter or a spatial modulator for light. Microscope objective (1, 100, 200) according to one of claims 6 to 13, in which at least one second pupil filter (219) is arranged between the first lens unit (203) and the second lens unit (205). Microscope objective (100) according to one of claims 1 to 14, in which the second lens unit (105) is designed afocally. Microscope objective (1, 100, 200) according to one of claims 1 to 15, which is designed as a microscope objective for interaction with an immersion medium adjacent to the first lens unit (3, 103, 203) on the object side. Microscope with a microscope objective (41, 141) according to one of the preceding claims. Microscope according to claim 17, which further comprises at least a third lens unit (43, 143) which is arranged on the image side of the objective (41, 141) and together with the microscope objective (41, 141) produces a real intermediate image. Microscope according to claim 18, in which the third lens unit (41, 141) is a tube lens group.

Images