Infinitely corrected microscope objective for scanning applications

Abstract

An infinitely corrected microscope objective (2) for scanning applications exhibits high image quality across the entire field of view and a small number of lenses dependent on the étendue (G), such that it has a first étendue (G1) in the range of 0.8 mm 2 up to 1.8 mm 2 and has at most nine lenses (Li; 1 ≤ i ≤ 9) or that it has a second etendue (G2) in the range of more than 1.8 mm 2 and has at most 15 lenses (Li; 1 ≤ i ≤ 15).

Description

[0001] The invention relates to an infinity-corrected microscope objective for scanning applications. The invention also relates to an optical assembly and a microscope with such an objective. Finally, the invention relates to the use of such an objective and a method for automated scanning of a sample.

[0002] Depending on the application, microscope lenses must meet different requirements.

[0003] Microscope objectives with a high light conductivity (etendue) are known from the state of the art.

[0004] US 2019 - 0324246, US 9746658, and US 8350904 concern dry lenses with high light transmittance. US 9939622, US 8988780, JP 2011075982, and DE 102011109783 concern immersion lenses with high light transmittance.

[0005] On the one hand, these lenses are very complex, but on the other hand, the image quality drops significantly towards the edges.

[0006] One object of the invention is to improve a microscope objective. A particular object is to provide an infinity-corrected microscope objective with a simplified design and improved optical properties.

[0007] This object is achieved by a microscope objective according to the present invention.

[0008] According to a first aspect, the lens may have an etendue in the range of 0.8 mm 2 up to 1.8 mm 2 and a maximum of 9 lenses. It can also have an etendue in the range of more than 1.8 mm 2 and have a maximum of 15 lenses. In this case, the etendue may in particular be smaller than 5.1 mm 2 .

[0009] Despite their reduced complexity, the lenses according to the invention exhibit a Strehl ratio of at least 0.8 across the entire field of view. This ensures high resolution across the entire field of view. This facilitates the merging of a plurality of partially overlapping images into a mosaic image.

[0010] In particular, the lenses may exhibit vignetting of less than 5%.

[0011] In particular, they can be apochromatically corrected over a spectral bandwidth of at least 200 nm, in particular in the range from 400 nm to 800 nm. They can be apochromatically corrected over a spectral bandwidth of at least 200 nm, in particular in the range from 400 nm to 700 nm. They can be apochromatically corrected in particular in the range from 460 nm to 660 nm.

[0012] They may preferably have a numerical aperture of at least 0.9.

[0013] The lenses according to the invention are particularly cost-effective to manufacture. They nevertheless result in a high degree of robustness of the optical system.

[0014] According to the invention, it was recognized that, particularly for scanning applications in which large, especially large-area, samples are examined, it is advantageous if the microscope objectives used for this purpose have a large field of view while simultaneously offering high resolution across the entire field of view. The Strehl ratio can be used to characterize the resolution. For the objectives according to the invention, this ratio is at least 0.8, in particular at least 0.83, in particular at least 0.89, in particular at least 0.9, across the entire field of view.

[0015] Especially for scanning applications, it may be necessary to capture a large number of images and then combine them into a mosaic image. This is preferably done automatically.

[0016] For high throughput, the total time required to acquire each image is a critical factor. This time depends on the acquisition time for each image and the number of images to be acquired. It is always desirable to reduce the total time required to acquire each image. This leads to faster results and increased throughput. Generally, this leads to lower costs.

[0017] An important factor influencing the total time required to acquire individual images is—in addition to the acquisition time for a single image—the field of view of the optical system. A larger field of view allows for larger areas to be captured in individual images. This means that fewer individual images are needed to image an extended sample. This leads to a reduced scanning time and a reduction in the effort required to combine the images into a mosaic image.

[0018] However, when increasing the field of view, it is critically important that the lens delivers high resolution across all relevant wavelength ranges. This requirement for high resolution with a simultaneously large field of view corresponds to an increase, specifically a maximization, of the optical conductance (etendue). The etendue is proportional to the square of the linear dimension, specifically the diameter, of the field of view. It is also proportional to the square of the numerical aperture (NA).

[0019] At the same time, it may be desirable, especially for routine applications, to reduce the complexity of the microscope objective. This can lead to cost savings. Reduced complexity refers, in particular, to a reduction in the number of required optical elements, especially lenses. Preferably, the number of aspherical lenses is reduced. This has been shown to lead to significant cost savings.

[0020] Finally, it can be advantageous for many applications if lenses with different properties, especially with different magnifications, can be used interchangeably. This makes it possible, for example, to initially acquire an overview image with a relatively lower resolution. The overview image can then be used to capture regions of interest (ROIs). These can then be examined in detail using a high-resolution lens.

[0021] To simplify lens exchange and ensure compatibility with standard microscope stands, it is advantageous if the lens is infinity corrected. This means that it is designed for infinity optics. In this case, the imaging light exits the lens as a parallel beam. This allows the use of a tube of any length.

[0022] The invention further recognizes that the complexity of lenses generally increases with increasing optical conductivity. Therefore, the lens can have a number of lenses that depends on the etendue (G).

[0023] Lenses according to the invention exhibit significantly reduced complexity, in particular a smaller number of lenses for a given optical conductance. However, due to their high Strehl ratio, they still ensure high resolution across the entire field of view.

[0024] The lenses with a maximum of nine lenses can have an object field height, ie half an object field diameter, of more than 0.3 mm.

[0025] The lenses with a maximum of 15 lenses can have an object field height, ie half an object field diameter, of more than 0.6 mm.

[0026] Vignetting may not exceed 5%, in particular not exceed 3%.

[0027] In the case of a lens with 9 elements, these can be arranged in 6 subgroups. These could, for example, be 3 single elements and 3 double elements.

[0028] In the case of a lens with a maximum of 15 elements, these can be arranged in 8 or 9 subgroups. The subgroups can include 2 triple cemented elements, 3 double cemented elements, and 3 single elements, or 2 triple cemented elements, 2 double cemented elements, and 5 single elements.

[0029] With such arrangements of the lenses, particularly advantageous optical properties could be achieved.

[0030] According to one aspect, the lens can be designed as a dry lens. It can have a numerical aperture (NA) in the range of 0.9-1.0. This leads to a particularly high resolution.

[0031] According to a further aspect, the lens can be designed as an immersion lens. It can have a numerical aperture (NA) of at least 1.0, in particular at least 1.1. This results in a particularly high resolution of the lens.

[0032] According to a further aspect, the lens can be designed entirely without aspherical lenses. This further reduces the complexity of the lens. This leads, in particular, to a reduction in costs.

[0033] In the case of 9 lenses, these must be made from at least 5, in particular at least 6, in particular at least 7, in particular at least 8 different types of glass.

[0034] In the case of a lens with a maximum of 15 lenses, these can be made of at least 8, in particular at least 10, in particular at least 12 different types of glass.

[0035] It has been shown that particularly good optical properties of the lens can be achieved by a suitable selection of different types of glass.

[0036] According to a further aspect, the second lens group of the objective may comprise two cemented elements.

[0037] For a lens with an etendue of less than 1.8 mm 2 These may be double cemented links.

[0038] For a lens with a rescue of more than 1.8 mm 2 These may be triple cemented links.

[0039] According to a further aspect, the lens can be apochromatically corrected over a bandwidth of at least 200 nm, in particular in a wavelength range between 400 nm and 800 nm, in particular in the range from 400 nm to 700 nm, in particular in the range from 460 nm to 660 nm. It has been shown that by reducing the bandwidth over which the lens is apochromatically corrected, the number of required lenses could be reduced.

[0040] Apochromatically corrected means that the maximum deviation of the focus position within the spectrum with respect to the reference wavelength lies within the depth of field.

[0041] According to a further aspect, the third lens group can have three subgroups (G31, G32, and G33). The first subgroup (G31) can have a positive refractive power. The second subgroup (G32) can have a negative refractive power. The third subgroup (G33) can have a negative refractive power.

[0042] Here and below, the order of the lens's optical elements is given in the direction from the object field to the image field. In relation to the lens, "front" refers to the side facing the object field, and "back" refers to the side facing away from the object field.

[0043] Further possible details of the lens are described below.

[0044] The lens may have a relatively short working distance. This may apply in particular: d:L<4.9×10−3, where d indicates the distance from the cover glass to the edge of the front lens surface of the objective, and L indicates the total distance between the object field and the vertex of the rear lens surface of the objective in the direction of the rays.

[0045] The working distance of the objective can also satisfy the following conditions: d0:L < 9×10−3, where d0 indicates the distance from the object field to the vertex of the front lens surface of the objective.

[0046] If the greatest distance of light rays, which emanate from an object on the optical axis, to the optical axis in the three subgroups G31, G32 and G33 of the third lens group G3 is denoted by h1, h2 and h3, then these quantities can in particular satisfy the following inequalities: 1.1 < h1:h2 < 1.8 and / or 1.2 < h2:h3 < 1.6.

[0047] In a lens with a maximum of 9 lenses, the third lens group G3 can have a first lens with positive refractive power and a second lens with negative refractive power.

[0048] Together with a tube lens unit, in particular with a tube lens with a focal length of 200 mm or with a focal length of 164.5 mm, the microscope objective according to the previous description can form an optical assembly.

[0049] A further object of the invention is to improve a microscope, in particular for scanning applications, in particular for optical mapping.

[0050] This task is solved by a microscope with an objective lens as described above. The advantages arise from those described above.

[0051] The microscope can be equipped with an automated scanning device. The scanning device can enable one-dimensional (linear) displacement of the sample, two-dimensional displacement of the sample, or three-dimensional displacement of the sample. In addition to linear displacements, the scanning device can also have one, two, or three rotational degrees of freedom. This allows for very flexible arrangement, especially for displacement, of the samples.

[0052] The scanning device may comprise an image capture device, in particular a digital image capture device, in particular a digital camera.

[0053] The scanning device may include an image processing device. This may, in particular, enable automated processing. This facilitates, in particular, the stitching of individual images into a mosaic image.

[0054] The microscope objectives described above are particularly advantageous for use in scanning applications, especially for optical mapping. They facilitate automated scanning of large, especially large-area, samples.

[0055] A further object of the invention is to improve a method for automated scanning of a sample. This object is achieved by a method comprising the following steps: - Providing a microscope according to the previous description, - Providing a sample to be examined, - taking at least two images of different sections of the sample, with the sections having an overlapping area and - Putting the pictures together to create a mosaic image.

[0056] The method can in particular be an optical mapping method.

[0057] Before the images are stitched together, they can be analyzed and / or processed using an image processing algorithm. This can simplify and / or improve the stitching process.

[0058] It is also possible to analyze and / or edit the composite mosaic image after the images have been combined using an image processing algorithm. This can further improve the quality.

[0059] To capture images of different sections of the sample, it can be moved linearly, two-dimensionally, or three-dimensionally. In particular, it can be moved stepwise.

[0060] The movement of the sample and the acquisition of successive images of different sections of the sample can be carried out in an automated manner.

[0061] Further details of the invention will become apparent from the description of exemplary embodiments with reference to the figures. They show: Fig. 1 schematically shows the structure of a microscope, Fig. 2 a schematic longitudinal section through the optical components of the microscope objective according to a first variant (E1), Fig. 3 a schematic longitudinal section through the optical components of the microscope objective according to a second variant (E2), Fig. 4 a schematic longitudinal section through the optical components of the microscope objective according to a third variant (E3), Fig. 5 a comparison of the object field height (h obj ) and the numerical aperture of the three lenses according to the variants E1, E2 and E3, Fig. 6-8 schematically show the course of the Strehl ratio over the field of view for light of different wavelengths and Fig. 9-11 schematically show the course of an intensity of the incident light illumination over the field of view of the three objectives according to the variants E1, E2 and E3.

[0062] In the Fig. Figure 1 shows an exemplary and schematic representation of the basic structure of a microscope 1. This illustration is intended to be exemplary and not restrictive.

[0063] The microscope 1 has infinity optics. This means that the beam path 3 runs parallel behind the objective lens 2. The area between the objective lens 2 and a tube lens 5 of a tube lens unit 6 is also referred to as the infinity space 4. An intermediate image is generated in an intermediate image plane 7 by the tube lens unit 6. The intermediate image can be viewed using an eyepiece 8. It can also be directed to an image capture device, in particular in the form of a camera 9. The camera 9 can be a digital camera, in particular.

[0064] An example is shown in the Fig. 1 also includes an illumination device 10. The illumination device 10 has a radiation source unit 11. A laser can serve as the radiation source unit 11, in particular.

[0065] The illumination device 10 may also comprise a beam splitter 12. With the aid of the beam splitter 12, the illumination radiation 3 can be guided through the objective 2 to a sample 13 to be observed. Fig. The beam path schematically illustrated in Figure 1 is particularly suitable for epifluorescence systems. The illumination can be implemented as Köhler illumination. Critical illumination is also possible. Instead of the beam splitter 12, a prism, particularly a cubic prism, can also be provided. Alternative variants for coupling the illumination radiation are known from the prior art.

[0066] Also shown schematically is the Fig. 1 a scanning device 14. The scanning device 14 has one or more displacement devices 15. Using the displacement devices 15, the sample 13 can be displaced relative to the beam path 3 in the microscope 1, in particular relative to the objective 2.

[0067] To clarify the working distance of lens 2, the Fig. 1 shows, as an example, the distance d from the cover glass 16 to the outer edge of the front lens surface 17 of the objective 2.

[0068] The distance from an object plane 18 to the vertex 19 of the front lens surface 17 is shown as d0.

[0069] L denotes the total distance between the object plane 18 and the vertex 19 of the rearmost lens surface of the objective 2 in the beam direction. The latter is in the Fig. 1 not explicitly shown.

[0070] The microscope 1 can have a footprint with a width b of at most 250 mm, in particular at most 205 mm.

[0071] Fig. 2 shows a longitudinal section through the arrangement of the optical components of the lens 2.

[0072] All variants (E1, E2 and E3) are suitable for use with cover glasses 16 with a thickness of 0.17 mm, a refractive index of nd=1.523 and the Abbe number vd=54.52 (related to a d-line of 587.562 nm).

[0073] In the Fig. 2 to 4 show the course of a central main ray HS and two marginal rays RS1, RS2 as an example.

[0074] For reasons of clarity, mechanical components of lens 2 are not shown in the figures.

[0075] In the Fig. 2, Fig. 3 and Fig. 4 also shows the cover glass (DG) 16.

[0076] Lens 2 is specifically an apochromatic lens 2.

[0077] In the Fig. The variant (E1) shown in Figure 2 is in particular a dry lens.

[0078] The lens 2 according to Fig. 2 has 9 lenses L1 to L9.

[0079] The optical design data of lens 2 according to Fig. 2 are summarized in Table 1. Table 1: optical design data of lens 2 according to Fig. 2: Oberfläche Nr. r (mm) d (mm) nd vd 1 -16.730 15.067 1.804 46.50 2 9.846 4.663 1.717 29.62 3 -59.780 4.416 4 Infinity 0.154 5 13.962 9.317 1.439 94.95 6 -13.757 2.902 1.691 54.71 7 -22.985 1.525 8 18.606 5.402 1.569 71.34 9 -13.522 1.000 2.003 28.27 10 45.162 0.673 11 15.918 3.165 1.569 71.34 12 66.860 0.354 13 9.509 4.089 1.592 68.37 14 12.624 0.130 15 5.477 6.684 1.883 40.76 16 4.311 0.288

[0080] The information on the refractive index (nd) and the Abbe number (vd) refers to the d-line (587.562 nm).

[0081] Further data of lens 2: Magnification: 40x NA: 0.95 L: 60.00 mm d: 0.150 mm d0: 0.288 mm d:L = 2.5 × 10 -3 d0:L = 4.8 × 10 -3 h ovj : 0.3125 mm G = 0.8699 mm 2

[0082] Lens 2 is suitable for use with a tube lens 5 with a focal length of 200 mm.

[0083] Lens 2 has three lens groups, G1, G2, and G3. The first lens group, G1, has a positive refractive power. It includes the lenses L1, L2, and L3.

[0084] The second lens group, G2, has a positive refractive power. The second lens group, G2, includes the lenses L4, L5, L6, and L7.

[0085] The lenses L4 and L5 form a double cemented element.

[0086] The lenses L6 and L7 form a double cemented element.

[0087] The third lens group G3 has a negative refractive power.

[0088] The third lens group G3 includes the lenses L8 and L9.

[0089] Lenses L8 and L9 form a double cemented element. Lens L8 is also known as optical element OE31. It has a positive refractive power.

[0090] The lens L9 is also known as optical element OE32. It has a negative refractive power.

[0091] The Fig. 2 lens 2 shown has an etendue of G = 0.8699 mm 2 on.

[0092] In the Fig. 3 shows a second variant (E2) of a lens 2.

[0093] The lens 2 according to Fig. 3 has 15 lenses L1 to L15.

[0094] The first lens group G1 includes the lenses L1 to L4.

[0095] The second lens group G2 includes the lenses L5 to L10.

[0096] The lenses L5 to L7 form a triple cemented element.

[0097] The lenses L8 to L10 form a triple cemented element.

[0098] The third lens group G3 has the lenses L11 to L15.

[0099] The lens L11 forms the subgroup G31.

[0100] The lenses L12 and L13 of the subgroup G32 form a double cemented element.

[0101] The lenses L14 and L15 of the subgroup G33 form a double cemented element.

[0102] The lens 2 according to Fig. 3 has an etendue G = 3.4799 mm 2 on.

[0103] For lens 2 according to Fig. 3 is a dry lens.

[0104] The optical design data of lens 2 according to Fig. 3 are summarized in Table 2. Table 2: optical design data of lens 2 according to Fig. 3: Oberfläche Nr. r (mm) d (mm) nd vd 1 142.661 1.000 1.855 24.80 2 28.105 1.000 1.883 40.76 3 17.981 3.915 4 -26.827 4.524 1.847 23.78 5 -38.436 3.193 1.883 40.76 6 -40.831 0.622 7 48.267 18.410 1.855 24.80 8 -169.890 0.100 9 85.109 10.276 1.592 68.37 10 -17.345 7.048 1.651 55.89 11 98.636 11.441 1.456 90.90 12 -52.386 1.652 13 41.646 7.455 1.439 94.95 14 -35.234 1.000 1.638 42.41 15 17.276 11.139 1.592 68.37 16 -80.941 0.226 17 22.295 7.149 1.618 63.39 18 36.105 0.154 19 13.395 3.409 1.497 81.55 20 16.175 2.613 21 9.008 7.079 1.456 90.90 22 22.142 0.205 23 7.450 3.319 1.816 46.62 24 5.590 0.894

[0105] The information on the refractive index (nd) and the Abbe number (vd) refers to the d-line (587.562 nm).

[0106] Further data of lens 2 according to Fig. 3: Magnification: 20x NA: 0.95 L: 107.99 mm d: 0.411 mm d0: 0.894 mm d:L = 3.8 × 10 -3 d0:L = 8.3 × 10-3 h obj : 0.625 mm G = 3.4799 mm 2

[0107] Lens 2 is suitable for use with a tube lens 5 with a focal length of 164.5 mm.

[0108] If the greatest distance of light rays emanating from an object on the optical axis to the optical axis in the three subgroups G31, G32 and G33 of the third lens group G3 is designated with h1, h2 and h3, then: h1 = 14.36 mm, h2 = 11.00 mm, h3 = 7.71 mm and thus h1 : h2 = 1.305 and h2 : h3 = 1.427.

[0109] In the Fig. 4 shows another variant (E3) of lens 2.

[0110] For lens 2 according to Fig. 4 is a water immersion lens.

[0111] The optical design data of lens 2 according to Fig. 4 are summarized in Table 3. Table 3: optical design data of lens 2 according to Fig. 4: Oberfläche Nr. r (mm) d (mm) nd vd 1 -44.873 1.000 1.581 40.75 2 14.040 25.000 1.613 44.49 3 22.604 6.243 4 -42.712 6.106 1.589 61.27 5 -18.702 1.669 1.673 38.26 6 -42.806 0.631 7 88.252 8.081 1.847 23.78 8 -142.575 10.312 9 77.638 25.000 1.637 42.41 10 45.052 17.776 1.439 94.95 11 -26.083 10.845 1.713 53.83 12 -37.642 4.540 13 60.618 8.938 1.439 94.95 14 -46.368 2.138 1.637 42.41 15 24.348 9.896 1.592 68.37 16 -205.611 0.544 17 25.823 13.153 1.487 84.47 18 73.714 0.664 19 13.538 7.990 1.456 90.90 20 25.889 0.100 21 8.331 6.725 1.883 40.76 22 2.084 1.957 1.459 67.82 23 Infinity 0.302 1.333 55.80

[0112] The information on the refractive index (nd) and the Abbe number (vd) refers to the d-line (587.562 nm).

[0113] Further data of lens 2 according to Fig. 4: Magnification: 20x NA: 1.0 (water immersion) L: 169.78 mm d: 0.302 mm d0: 0.302 mm d:L = 1.8 x 10-3 d0:L = 1.8 x 10-3 hobj: 0.625 mm G = 4.6649 mm 2

[0114] Lens 2 is suitable for use with a tube lens 5 with a focal length of 164.5 mm.

[0115] The lens 2 (E3) according to Fig. 4 has an etendue G = 4.6649 mm 2 on.

[0116] If the greatest distance of light rays emanating from an object on the optical axis to the optical axis in the three subgroups G31, G32 and G33 of the third lens group G3 is designated with h1, h2 and h3, then: h1 = 16.55 mm, h2 = 13.78 mm, h3 = 9.79 mm and thus h1 : h2 = 1.301 and h2 : h3 = 1.408.

[0117] In the Fig. 5 schematically shows the field heights (hobj), ie half the field diameter in relation to the numerical aperture (NA) of the objectives (E1, E2, and E3). Fig. 5 the curves for an etendue G = 0.8 mm 2 , G = 1.8 mm 2 and G = 5.1 mm 2Objectives 2 with a numerical aperture of at least 1 are immersion objectives. Objectives with a numerical aperture NA < 1 can be designed as dry objectives. Accordingly, the figure distinguishes three different areas of the etendue. These are designated "Level 1," "Level 2," and "Level 3."

[0118] In the Fig. 6-8 are the Strehl ratios of the three lenses 2 according to the Fig. 2, Fig. 3 and Fig. 4 for light with a wavelength λ1 = 460 nm, λ2 = 546 nm and λ3 = 660 nm.

[0119] As can be seen from the figures, the Strehl ratio across the entire field of view is greater than 0.8. For individual wavelengths or a limited wavelength range, the Strehl ratio across the entire field of view is even greater, in particular greater than 0.83, and in particular greater than 0.9.

[0120] In the Fig.To illustrate the marginal light falloff, the relative illumination intensity at a wavelength of 546.074 nm is shown across the field of view in Figures 9-11.

[0121] As can be seen from the figures, the lenses 2 lead to a homogeneous illumination of the field of view with a small vignetting when illuminated by incident light. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2019 - 0324246

[0004] US 9746658

[0004] US 8350904

[0004] US 9939622

[0004] US 8988780

[0004] JP 2011075982

[0004] FROM 102011109783

[0004]

Claims

[1] Infinity corrected microscope objective (2) for scanning applications having 1.

1. a first lens group (G1) with positive refractive power, 1.

2. a second lens group (G2) with positive refractive power and 1.

3. a third lens group (G3) with negative refractive power, 1.

4. where the microscope objective (2) 1.4.

1. has a numerical aperture (NA) of at least 0.9, 1.4.

2. has a Strehl ratio of at least 0.8 across the entire field of view, 1.4.

3. has less than 5% vignetting, 1.4.4 is apochromatically corrected over a spectral bandwidth of at least 200 nm and 1.4.

5. has a small number of lenses depending on the etendue (G), such that 1.4.5.

1. that there is a first etendue (G1) in the range of 0.8 mm 2 up to 1.8 mm 2 and has a maximum of nine lenses (Li; 1 ≤ i ≤ 9) or 1.4.5.

2. that there is a second etendue (G2) in the range of more than 1.8 mm 2 and has a maximum of 15 lenses (Li; 1 ≤ i ≤ 15). [2] Microscope objective (2) according to claim 1, characterized by that it is designed as a dry lens and has a numerical aperture (NA) in the range of 0.9 to 1.

0. [3] Microscope objective (2) according to claim 1, characterized by that it is designed as an immersion lens and has a numerical aperture (NA) of at least 1.

0. [4] Microscope objective (2) according to one of the preceding claims, characterized by that it does not have aspherical lenses. [5] Microscope objective (2) according to one of the preceding claims, characterized by that the second lens group (G2) has two cemented elements (G21, G22). [6] Microscope objective (2) according to one of the preceding claims, characterized bythat it is apochromatically corrected over a bandwidth of at least 200 nm in a wavelength range between 400 nm and 800 nm. [7] Microscope objective (2) according to one of the preceding claims characterized by that the third lens group (G3) has three subgroups (G31, G32 and G33), wherein the first subgroup (G31) has a positive refractive power, the second subgroup (G32) has a negative refractive power and the third subgroup (G33) has a negative refractive power. [8] Microscope objective (2) according to one of the preceding claims characterized by following optical design data: Surface No. r (mm) d (mm) and vd 1 -16.730 15.067 1.804 46.50 2 9.846 4.663 1.717 29.62 3 -59.780 4.416 4 Infinity 0.154 5 13.962 9.317 1.439 94.95 6 -13.757 2.902 1.691 54.71 7 -22.985 1.525 8 18.606 5.402 1.569 71.34 9 -13.522 1.000 2.003 28.27 10 45.162 0.673 11 15.918 3.165 1.569 71.34 12 66.860 0.354 13 9.509 4.089 1.592 68.37 14 12.624 0.130 15 5.477 6.684 1.883 40.76 16 4.311 0.288 [9] Microscope objective (2) according to one of claims 1 to 7 characterized by following optical design data: Surface No. r (mm) d (mm) and vd 1 142.661 1.000 1.855 24.80 2 28.105 1.000 1.883 40.76 3 17.981 3.915 4 -26.827 4.524 1.847 23.78 5 -38.436 3.193 1.883 40.76 6 -40.831 0.622 7 48.267 18.410 1.855 24.80 8 -169.890 0.100 9 85.109 10.276 1.592 68.37 10 -17.345 7.048 1.651 55.89 11 98.636 11.441 1.456 90.90 12 -52.386 1.652 13 41.646 7.455 1.439 94.95 14 -35.234 1.000 1.638 42.41 15 17.276 11.139 1.592 68.37 16 -80.941 0.226 17 22.295 7.149 1.618 63.39 18 36.105 0.154 19 13.395 3.409 1.497 81.55 20 16.175 2.613 21 9.008 7.079 1.456 90.90 22 22.142 0.205 23 7.450 3.319 1.816 46.62 24 5.590 0.894 [10] Microscope objective (2) according to one of claims 1 to 7 characterized by following optical design data: Surface No. r (mm) d (mm) and vd 1 -44.873 1.000 1.581 40.75 2 14.040 25.000 1.613 44.49 3 22.604 6.243 4 -42.712 6.106 1.589 61.27 5 -18.702 1.669 1.673 38.26 6 -42.806 0.631 7 88.252 8.081 1.847 23.78 8 -142.575 10.312 9 77.638 25.000 1.637 42.41 10 45.052 17.776 1.439 94.95 11 -26.083 10.845 1.713 53.83 12 -37.642 4.540 13 60.618 8.938 1.439 94.95 14 -46.368 2.138 1.637 42.41 15 24.348 9.896 1.592 68.37 16 -205.611 0.544 17 25.823 13.153 1.487 84.47 18 73.714 0.664 19 13.538 7.990 1.456 90.90 20 25.889 0.100 21 8.331 6.725 1.883 40.76 22 2.084 1.957 1.459 67.82 23 Infinity 0.302 1.333 55.80 [11] Optical assembly comprising 11.

1. a microscope objective (2) according to one of the preceding claims and 5 11.

2. a tube lens unit (6) with a tube lens (5) with a focal length of 200 mm or 164.5 mm. [12] Microscope (1) with a microscope objective (2) according to one of claims 1 to 10. [13] Microscope (1) according to claim 12, characterized by an automated scanning device (14). [14] A method for automated scanning of a sample comprising the following steps: 14.

1. Providing a microscope (1) according to one of claims 12 to 13, 14.

2. Providing a sample to be examined, 14.

3. Taking at least two images of different sections of the sample, with the sections having an overlapping area, 14.

4. Assemble the images into a mosaic.

Images