Abstract:
A variable microscope system, which, beginning at the object plane, includes a main lens system, a zoom lens system consisting of several lens groups, and a relay system connected in series to the zoom lens system. In the microscope system, according to the invention, at least one main lens system for infinite mapping of an object is provided and the zoom lens system is designed in such a way that the infinite beam path from the lens system is mapped in an intermediate image, wherein an aperture collimation is provided in a subsequently positioned relay system. An advantage of the microscope system, according to the invention, versus prior art lies in an improved eye pupil adjustment to the illumination as well as to the observation of samples with the contrast method.

Description:
[0001]    This application claims priority to German Patent Application No. 10 2009 041 994.2 filed on Sep. 18, 2009, said application is incorporated herein by reference in it&#39;s entirety. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a variable microscope system, which, beginning at the object plane, comprises a main lens system, a zoom lens system consisting of several lens groups, and a relay system connected in series to the zoom lens system. 
       BACKGROUND OF THE INVENTION 
       [0003]    In principle, microscope systems of this general type are known. Thereby, the adjustment of the zoom to the lens system and tube interface is of vital importance and must be inventively solved every time a new system of this type is to be developed (see SPIE Vol. 3482 XP009013507). 
         [0004]    If an illumination is to be coupled in via the zoom system—with the advantage of an automatically adjusted field and aperture illumination—the entrance and exit pupils of the individual components must be synchronized as precisely as possible. This applies to the position of the pupils as well as their diameters. 
         [0005]    The pupil adjustment defines the aperture for the imaging beam path across the zoom area as well the high vignetting, which is frequently connected thereto and varies with the zoom position. In this respect problems occur, particularly with the coaxial illumination since the object functions as an additional reflective element requiring a separate pupil adjustment for the illumination light and the reflected light. 
         [0006]    While in higher magnification compound microscopes a magnification change is inevitably connected to a lens change, zoom systems are traditionally used in stereo microscopes due to lower magnifications and smaller apertures seen in stereo microscopes. Beginning with switchable Galilean systems, the transition was made to continuously operating afocal zoom systems with positive angular magnification during the course of further developments, as described, e.g., in DE 202 07 780 U1, DE 198 37 135 A1, and DE 103 59 733 A1. 
         [0007]    Such systems are installed in the parallel beam path between the lens system and the tube lens. They are characterized by a relatively short transfer size and an aperture, usually positioned inside the system. 
         [0008]    Said aperture is mapped on reciprocating pupil images through the respective motion sequence of the zoom components. This also applies to the system described in US 2006/0092504, whereby, however, the mapping of the aperture in the direction of the tube lens, i.e., the exit pupil, is compensated through the additional utilization of a third adjustable lens group. 
         [0009]    Even though this comes closer to a solution for the problem of coupling an illumination via the zoom system, a trouble-free coaxial illumination is still not possible due to the greatly migrating entrance pupil position. 
         [0010]    In US 2006/0114554A1, a stable entrance pupil is created by means of a physical aperture positioned before the afocal zoom. However, hereby it is disadvantageous that the exit pupil position of the afocal zoom system varies greatly. 
       SUMMARY OF THE INVENTION 
       [0011]    Based on the aforementioned, the invention creates a variable microscope system which, compared to prior art, allows for an improved pupil adjustment with regard to illumination as well as with regard to the application of contrast methods. An advantage of the microscope system, according to the invention, versus prior art lies in an improved eye pupil adjustment to the illumination as well as to the observation of samples with the contrast method, such as phase contrast and differential interference contrast (DIC). 
         [0012]    According to the invention, improvements over the prior art are made with a microscope system of the above described type, wherein
       at least one main lens system for infinite mapping of an object is provided, and   the zoom lens system is designed such that the infinite beam path from the lens system is mapped in an intermediate image, wherein   an aperture collimation is provided in a subsequently positioned relay system.       
 
         [0016]    The terms variable magnification system, zoom lens system, and zoom system shall be used as synonyms in the following description. If several main lens systems are assigned to the microscope system, according to the invention, they are interchangeable. Regardless of the deployed main lens system and the adjusted magnification, the intermediate image, according to embodiments of the invention, exhibits not only a fixed position but also a fixed image size. 
         [0017]    The relay system for the mapping of the intermediate image is positioned in an eyepiece image plane or on a camera. 
         [0018]    In connection with the mapping in an eyepiece image plane, the optical relay system can also be designed as an imaging system with a binocular tube. 
         [0019]    Furthermore, the scope of the invention includes the provision of the microscope system, according to the invention, with a device for the reflection of an illumination beam path. In this case, it is advantageous to provide for a field stop in the intermediate image plane. 
         [0020]    With the mapping of the object via the stationary intermediate image it is possible to adjust the entrance pupil as well as the exit pupil of the microscope system to the desired conditions, particularly to an illumination to be coupled in. 
         [0021]    This option for pupil adjustment results primarily in an improved image quality during the application of microscopic contrast methods for reflected light and transmitted light imaging. The field stop adds to further improved contrast. Furthermore, high cleanness tolerances with regard to the optical assemblies near the intermediate image are avoided because, due to the relatively large aperture on the image side, the influence of small contaminants regarding wavefront deformation decreases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    In the following, the invention shall be further explained by embodiment examples. 
           [0023]      FIG. 1  is a first embodiment example with a variable magnification system, which consists of three lens groups, a relay system, consisting of two lens groups with an aperture diaphragm positioned between said two lens groups, and a first variation of the coupling of the illumination light via a fiber; 
           [0024]      FIG. 2  is a second embodiment example with a variable magnification system, which consists of four lens groups, a relay system, consisting, as in  FIG. 1 , of two lens groups with an aperture diaphragm positioned between said two lens groups, and a second variation of the coupling of the illumination light via a fiber. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The design data of the first embodiment example in  FIG. 1  are shown in the following table. For the main lens system applies: 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Area 
                 Radius of 
                 Thickness 
                 Refractive index 
                 Abbe number 
               
               
                 FL 
                 curvature r 
                 d 
                 n e   
                 v e   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0 
                   
                 63.860 
                   
                   
               
               
                 1 
                 −44.931 
                 6.765 
                 1.72341 
                 50.4 
               
               
                 2 
                 70.783 
                 10.087 
                 1.43985 
                 94.6 
               
               
                 3 
                 −40.742 
                 0.100 
               
               
                 4 
                 103.148 
                 12.000 
                 1.43985 
                 94.6 
               
               
                 5 
                 −50.977 
                 0.150 
               
               
                 6 
                 38.280 
                 9.000 
                 1.74791 
                 44.6 
               
               
                 7 
                 64.674 
                 5.000 
                 1.51045 
                 61.0 
               
               
                 8 
                 37.660 
                 7.500 
               
               
                 9 
                 166.541 
                 4.500 
                 1.73739 
                 51.2 
               
               
                 10 
                 26.500 
                 12.500 
                 1.48794 
                 84.1 
               
               
                 11 
                 −370.371 
                 2.000 
               
               
                   
               
             
          
         
       
     
         [0026]    The zoom lens system in this example embodiment is designed with three lens groups LG 1  to LG 3  and the following data, wherein Z 1  to Z 3  designate the variable distances between the lens groups: 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 12 
                 84.234 
                 4.000 
                 1.61664 
                 44.3 
               
               
                 13 
                 33.122 
                 10.000 
                 1.53019 
                 76.6 
               
               
                 14 
                 6565.176 
                 0.150 
               
               
                 15 
                 37.819 
                 6.000 
                 1.53019 
                 76.6 
               
               
                 16 
                 84.405 
                 28.099 
               
               
                 17 
                 −37.135 
                 3.000 
                 1.88815 
                 40.5 
               
               
                 18 
                 −13.938 
                 2.000 
                 1.53430 
                 48.5 
               
               
                 19 
                 11.327 
                 4.842 
               
               
                 20 
                 −10.799 
                 2.000 
                 1.57098 
                 70.9 
               
               
                 21 
                 26.066 
                 4.300 
                 1.74791 
                 44.6 
               
               
                 22 
                 −12.366 
                 2.000 
                 1.75737 
                 52.0 
               
               
                 23 
                 −30.461 
                 17.976 
               
               
                 24 
                 −189.820 
                 2.500 
                 1.80650 
                 34.7 
               
               
                 25 
                 18.443 
                 6.000 
                 1.43985 
                 94.6 
               
               
                 26 
                 −23.746 
                 0.100 
               
               
                 27 
                 28.103 
                 6.000 
                 1.52679 
                 70.1 
               
               
                 28 
                 −26.743 
                 44.507 
               
               
                 ZWB1 
               
               
                   
               
             
          
         
       
     
         [0027]    Through a variation of the distances Z 1  to Z 3  between the lens groups of the zoom lens system, focal lengths can be adjusted for example as follows: 
         [0000]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 f in mm 
               
             
          
           
               
                   
                 11.4 mm 
                 13.8 mm 
                 22.2 mm 
                 34.8 mm 
                 70 mm 
                 140 mm 
               
               
                   
               
             
          
           
               
                 Z1 
                 4.940 
                 9.905 
                 20.255 
                 28.015 
                 39.195 
                 53.420 
               
               
                 Z2 
                 47.196 
                 41.250 
                 28.280 
                 17.900 
                 5.013 
                 11.995 
               
               
                 Z3 
                 38.279 
                 39.260 
                 41.880 
                 44.500 
                 46.207 
                 25.000 
               
               
                 S EP   
                 44.9 
                 55.4 
                 81.3 
                 100.8 
                 85.1 
                 313.1 
               
               
                   
               
             
          
         
       
     
         [0028]    In the table above, S EP  denotes the entrance pupil position with regard to the zoom lens system and for which a telecentric beam path is ensured in case of large object fields. 
         [0029]    The zoom lens system is connected to a relay system with binocular output, which exhibits the following data: 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 30 
                 −26.440 
                 2.000 
                 1.61664 
                 44.3 
               
               
                 31 
                 24.321 
                 4.000 
                 1.43985 
                 94.6 
               
               
                 32 
                 −13.294 
                 0.100 
               
               
                 33 
                 515.475 
                 4.000 
                 1.62286 
                 60.1 
               
               
                 34 
                 −32.383 
                 20.864 
               
               
                 AB 36 
                 0.000 
                 60.000 
               
               
                 37 
                 102.461 
                 5.000 
                 1.76859 
                 26.3 
               
               
                 38 
                 −16.156 
                 4.000 
                 1.58212 
                 53.6 
               
               
                 39 
                 17.509 
                 11.642 
               
               
                 40 
                 24.792 
                 7.000 
                 1.53019 
                 76.6 
               
               
                 41 
                 −18.547 
                 3.000 
                 1.76859 
                 26.3 
               
               
                 42 
                 −107.112 
                 61.500 
               
               
                 43 
                 0.000 
                 162.000 
                 1.51872 
                 64.0 
               
               
                 44 
                 0.000 
                 38.130 
               
               
                 ZWB2 
               
               
                   
               
             
          
         
       
     
         [0030]    The zoom factor ZF herein is 12.5×. AB in the above table denotes the aperture diaphragm, while ZWB 2  denotes the second intermediate image plane. 
         [0031]      FIG. 1  shows the optical assemblies of this embodiment example, structured as main lens system, zoom lens system, and relay system with binocular exit. 
         [0032]    The object plane is designated with O. The lens system consists of seven lenses with the optically active areas  1  to  11  as listed in the table above. For example, the lens system has a focal length of f=80 mm. 
         [0033]    The zoom lens system comprises the lens group LG 1  with positive refractive power, lens group LG 2  with negative refractive power, and lens group LG 3  with positive refractive power. 
         [0034]    The lens group LG 1  consists of 3 lenses with the optically active areas  12  to  16  and is permanently positioned in the beam path. The lens group LG 2  consists of five lenses with optically active areas  17  to  23  and is adjustable relative to the lens group LG 1 . 
         [0035]    The lens group LG 3  consists of three lenses with the optically active areas  24  to  28  and is adjustable relative to the lens groups LG 1  and LG 2 . 
         [0036]    Through the shift of the lens groups LG 2  to LG 4 , the distances Z 1  to Z 3  are altered and, therefore, the magnification of the object image varied. 
         [0037]    The intermediate image ZWB 1  has a fixed position, which is independent from the respective positions of the lens groups LG 2  to LG 3  and therefore from the adjusted magnification. 
         [0038]    The imaging system consists of the lens groups LG 4  and LG 5 , between which the aperture diaphragm AB is positioned. The image plane has the designation B. 
         [0039]    This example embodiment deviates from a fixed design of the pupil mapping in favor of a simpler zoom movement. Therefore, the entrance pupil position is no longer constant for all zoom positions but changes its position in accordance with the zoom position. However, since the adjustment of exit and entrance pupil position, as described above, is crucial for the illumination of large object fields, the entrance pupil position of the zoom lens system is adjusted in these zoom positions to the exit pupil position of the main lens system and deviates from this ideal position for greater magnification and therefore smaller object fields. 
         [0040]    The relay system, connected in series to the zoom lens system, realizes the image reversal, so that a side-correct, upright image appears at the eyepiece exit. The aperture diaphragm AB positioned in the relay system presents advantages for the illumination as well as for the execution of simple tubes. The aperture diaphragm AB, fixed with regard to position and diameter, allows for a simple adjustment to a given light source, particularly with regard to the coupling of the illumination light via a fiber. 
         [0041]    For example, as shown in  FIG. 1 , the mapping of the fiber end with additional optics LG 6  and LG 7  via a mirror S 1 , a beam splitter T 1 , and a mirror S 2  is effected to the aperture diaphragm AB near the first lens group LG 4  of the relay system. The introduction of the illumination light is effected with a light guide cable or liquid light guide LWL known from prior art. 
         [0042]    The advantages of an aperture positioned in the relay system lie in the accessibility of the aperture as well as in the aperture-effected beam trajectory. Therefore, due to the tightest constriction of the beam bundles, the diameters of the beam splitter T 1  and the subsequent illumination and/or the subsequent tube are minimal. 
         [0043]    In one embodiment, the microscope system, according to the invention, is equipped with a relay system, which exhibits an infinite beam path. Via said infinite beam path, a universal microscope illumination, such as a halogen or HBO lamp, can be coupled in. A particularly simple variation results from the accessibility of the aperture diaphragm plane since a fiber exit positioned at this location, with a field stop at the first intermediate image ZWB 1 , represents a complete Koehler illumination. 
         [0044]      FIG. 2  shows a second example embodiment. Herein, the zoom lens system consists of four lens groups LG 1  to LG 4 , and the relay system consists once again of two lens groups LG 5  and LG 6  with the aperture diaphragm AB between them. 
         [0045]    If we look at the illustration of this fixed aperture diaphragm from the rear, i.e., from the relay system toward the object, we obtain in this embodiment example a fixed entrance pupil position for the zoom lens system across the entire zoom area. In this case, the zoom lens system is designed in such a way that the infinite beam path from the lens system produces a fixed intermediate image, and a fixed entrance pupil of the zoom lens system is mapped in a fixed exit pupil outside the zoom lens system. Due to this fixed entrance pupil position of the overall system, it is possible to realize a telecentric zoom on the object side with appropriate selection of the exit pupil position of the main lens system. 
         [0046]    Notwithstanding the first embodiment example as shown in  FIG. 1 ,  FIG. 2  shows how it is possible to directly couple a fiber via the infinite beam path in the relay system at the point of the aperture diaphragm AB as well as to establish a sliding area for the subsequent binocular exit. 
         [0047]    The zoom lens system hereto is, e.g., designed as follows: 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Area 
                 Radius of 
                 Thickness 
                 Refractive index 
                 Abbe number 
               
               
                 FL 
                 curvature r 
                 D 
                 n e   
                 v e   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 99.3139 
                 8.000 
                 1.48794 
                 84.1 
               
               
                 2 
                 −49.6449 
                 4.000 
                 1.70055 
                 36.1 
               
               
                 3 
                 −144.3994 
                 0.150 
               
               
                 4 
                 50.0155 
                 6.000 
                 1.49845 
                 81.0 
               
               
                 5 
                 1615.6495 
                 40.580 
               
               
                 6 
                 −47.8934 
                 3.000 
                 1.74791 
                 44.6 
               
               
                 7 
                 −17.8663 
                 2.000 
                 1.48915 
                 70.1 
               
               
                 8 
                 13.3100 
                 38.186 
               
               
                 9 
                 −14.0449 
                 3.000 
                 1.49845 
                 81.0 
               
               
                 10 
                 12.3340 
                 2.000 
                 1.67719 
                 37.9 
               
               
                 11 
                 45.7264 
                 6.393 
               
               
                 12 
                 −127.7170 
                 2.500 
                 1.72539 
                 34.5 
               
               
                 13 
                 18.6138 
                 6.000 
                 1.49845 
                 81.0 
               
               
                 14 
                 −26.4559 
                 25.000 
               
               
                 15 
                 28.7094 
                 4.000 
                 1.52880 
                 65.92 
               
               
                 16 
                 −39.6605 
                 25.000 
               
               
                 ZWB 1 
               
               
                   
               
             
          
         
       
     
         [0048]    Here the zoom factor ZF is 25×. 
         [0049]    Through variation of the distances Z 1  to Z 4  between the lens groups of this zoom lens system, focal lengths f can be adjusted as follows. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 f□ in mm 
               
             
          
           
               
                   
                 10 mm 
                 16 mm 
                 25 mm 
                 50 mm 
                 100 mm 
                 250 mm 
               
               
                   
               
             
          
           
               
                 Z1 (D5) 
                 42.320 
                 56.507 
                 64.379 
                 68.253 
                 56.360 
                 25.000 
               
               
                 Z2 (D8) 
                 54.010 
                 24.513 
                 18.600 
                 15.407 
                 12.082 
                 6.390 
               
               
                 Z3 (D11) 
                 8.000 
                 24.130 
                 18.552 
                 5.000 
                 5.392 
                 38.180 
               
               
                 Z4 (D16) 
                 5.820 
                 5.000 
                 8.619 
                 21.490 
                 36.316 
                 40.580 
               
               
                 S EP   
                 50 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                   
               
             
          
         
       
     
         [0050]    S EP  in the above table denotes the entrance pupil, onto which main lens systems are to be displayed, which are not further described herein. 
         [0051]    The zoom lens system is connected to a relay system which, starting at the intermediate image ZWB 1 , exhibits the following data: 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Area 
                 Radius of 
                 Thickness 
                 Refractive index 
                 Abbe number 
               
               
                 FL 
                 curvature r 
                 D 
                 n e   
                 v e   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 ZWB1 
                   
                 38.996 
                   
                   
               
               
                 18 
                 −14.9315 
                 2.000 
                 1.51045 
                 61.0 
               
               
                 19 
                 10.7947 
                 6.393 
                 1.49845 
                 81.0 
               
               
                 20 
                 −17.4114 
                 0.100 
               
               
                 21 
                 94.6144 
                 4.000 
                 1.49845 
                 81.0 
               
               
                 22 
                 −34.1390 
                 40.000 
               
               
                 AB 
                 Infinite 
                 5.000 
               
               
                   
                 51.2072 
                 3.000 
                 1.53019 
                 76.6 
               
               
                   
                 −153.8027 
                 2.000 
                 1.66883 
                 35.7 
               
               
                   
                 Infinite 
                 15.020 
               
               
                   
                 55.3108 
                 7.500 
                 1.62286 
                 60.1 
               
               
                   
                 33.4284 
                 70.000 
               
               
                   
                 Infinite 
                 80.000 
                 1.51872 
                 64.0 
               
               
                   
                 Infinite 
                 25.000 
               
               
                 ZWB 2 
               
               
                   
               
             
          
         
       
     
         [0052]    If the aperture diaphragm plane were not directly reachable, it is possible to map the fiber exit by means of adjustment optics also at this location, as shown as an example in the embodiment, according to  FIG. 1 . 
         [0053]    A further advantage of the infinity space in the relay system is the adjustability of the second group in the relay system and the resulting simple realization of ergonomic tubes. In addition, the second reflection—containing the image orientation—can be designed with an adjustable angle. Therefore, additional adjustments regarding ergonomics are possible. 
         [0054]    If a camera exit is desired, the beam splitter T 1  can, for example, be exchanged by a shift with another beam splitter T 1  with deviating deflection angle. 
         [0055]    With the imaging of the object via an intermediate image, the aperture, usually positioned in the zoom system, according to prior art, is bypassed, creating a real image for the pupil mapping. Since the aperture diaphragm in the relay system constitutes a conjugated plane with regard to the exit pupil of the main lens system, the option is hereby created to effect pupil procedures for contrast methods at this location. The fact that the diameter of the aperture as well as the angle of field at the aperture diaphragm behind the zoom lens system is constant throughout the entire zoom provides significant advantages for the design of the contrast devices. 
         [0056]    For example, a reflected-light phase contrast method can be realized as shown in the embodiment example in accordance with  FIG. 2 . With a ring of fixed size on the illumination side, it is possible to illuminate through an aperture plane, which is split by the beam splitter T 1 . The phase ring conjugated thereto is to be positioned after the mirror in the imaging beam path. 
         [0057]    The DIC method, more frequently used with reflected light, whereby a birefringent prism in the illumination and imaging beam path is equally effective, can also be realized due to the constant angle of field. The constant angle of field on the image side corresponds on the object side to image splitting of varying size, depending on the zoom. Since the numerical aperture on the object side also changes with the zoom, an automatic adjustment of image splitting and numerical aperture is ensured. 
         [0058]    With contrast methods, such as phase contrast and differential interference contrast (DIC), the visualization of certain object details is achieved through pupil procedures. Due to the aperture, which is fixed in position and size over the entire zoom area, a Wollaston prism for differential angle splitting can be introduced as well as a reflected-light phase contrast be realized. 
       LEGEND 
       [0000]    
       
         LG 1  to LG 8  Lens groups 
         O Object plane 
         B Image plane 
         ZWB 1  First intermediate image 
         ZWB 2  Second intermediate image 
         AB Aperture diaphragm 
         S 1 , S 2  Mirror 
         T 1  Beam splitter 
         Z 1  to Z 4  Distances 
         LB Field stop