Abstract:
The invention concerns a (stereoscopic) surgical microscope having a system for reflecting in illumination in which the illumination beam path ( 5 ) is switched into the microscope&#39;s main beam path via a deflection element ( 1 ) whose diameter exceeds the spacing of the observation beam paths ( 3 ). Different illumination angles for the specimen ( 10 ) can be generated by means of a stop ( 8 ) that is shiftable radially about the axis ( 5   a ) of the illumination beam path ( 5 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims priority of the German patent application 101 44 062.6 filed Sep. 7, 2001 which is incorporated by reference herein.  
         FIELD OF THE INVENTION  
         [0002]    The invention concerns a stereoscopic surgical microscope having a system for reflecting in illumination with which an illumination beam path is switched via a deflecting prism into the main beam path of the microscope.  
         BACKGROUND OF THE INVENTION  
         [0003]    Reflected-in beam paths for illumination of a specimen field are used in a wide variety of applications, and in particular in the medical field. Usually the illumination beam path is reflected into the main beam path of the microscope via a deflecting mirror or deflecting prism, which as a rule is mounted on the axis of the microscope&#39;s main beam path. This results in illumination of the specimen surface directly on the axis of a microscope&#39;s main beam path. If the illumination is applied laterally from the axis of the main beam path, this usually results in more or less undesirable shadowing.  
           [0004]    For a number of applications, however, an illumination deviating from the observation axis is desirable. The Zeiss company achieves this, as is known from DE-A-40 28 605 and DE-A-197 28 035, by way of a second mirror. For ophthalmic surgery in particular, a so-called “zero-degree” illumination (“zero-degree” indicating illumination on the axis of the main beam path) is inclined at a small angle of e.g. 6 degrees in order to improve the visibility of the surgical field.  
           [0005]    In a particular embodiment of the system for reflecting in illumination (cf. DE-A-196 50 773), the Möller company asserted the idea of introducing light directly into the observation beam paths.  
           [0006]    In order to achieve partial darkening of the specimen field, stops are used as necessary in the illumination beam path (cf. U.S. Pat. No. 4,715,714 in this context). These are located, however, in the illumination location conjugated with the specimen field. Stops of this kind can be used, for example, to reduce the so-called “red reflection,” once again in ophthalmic surgery. In order deliberately to reduce tissue stress, other stops serve to exclude the light directed via the respective mirror.  
           [0007]    The inventor has recognized that the known systems are disadvantageous in the following respects:  
           [0008]    a) At present, continuous adaptation of the illumination angle in the radial and axial directions with respect to the microscope&#39;s main beam path is not possible.  
           [0009]    b) Oblique illumination via two mirrors makes possible only predefined illumination angles in the radial direction with respect to the microscope&#39;s main beam path, thereby resulting in a limitation in contrast selection.  
           [0010]    c) Reflection into the observation beam paths is suitable for illumination in narrow channels, but results on the one hand in poor contrast and on the other hand in solutions that are difficult to design.  
           [0011]    d) Because the illumination is reflected into the convergent beam path, the arrangement as defined in DE-A-36 23 613 results in light loss and double images.  
         SUMMARY OF THE INVENTION  
         [0012]    The primary object of the invention is thus to create an illumination apparatus which makes it possible for light beams to strike the specimen field at variable angles, thus eliminating the disadvantages mentioned above.  
           [0013]    This object is achieved by way of the following actions:  
           [0014]    The illumination beam path is switched into the microscope&#39;s main beam path via a deflecting mirror whose diameter exceeds the spacing of the observation beam paths and which has unobstructed openings for the observation beam paths;  
           [0015]    By way of a stop that is radially adjustable about the axis of the illumination beam path, any desired incidence angles can be achieved for the light beams illuminating the specimen.  
           [0016]    Shifting the lens elements of the illuminating optical system in the illumination beam path causes the illuminated specimen field to become large with a small illumination pupil or small with a large illumination pupil.  
           [0017]    These stops are configured to be insertable and removable, for example pivotable in and out, as necessary.  
           [0018]    Shifting of the entire illuminating optical system, i.e. the illumination pupil via the deflecting element, also modifies the illumination angle.  
           [0019]    According to particular embodiments, the stops, can be configured as a diaphragm, thin film, LCD, or electrochromic layer.  
           [0020]    A combination system for reflecting in illumination, as depicted in FIG. 1, is preferably used in medical applications.  
           [0021]    The situation is thus improved by the invention in the following ways:  
           [0022]    Because, according to the present invention, the illumination beam path is reflected in via a deflecting mirror whose diameter exceeds the spacing of the observation beam paths; and because of the use, according to the present invention, of a stop that can be shifted radially in the illumination beam path, the incidence angle of the light beams illuminating the specimen can be modified in the radial direction with respect to the microscope&#39;s main beam path;  
           [0023]    because stops are used in the illumination beam path, additional variations can be achieved, together with the illuminating optical system, to modify the specimen field illumination, for example in order to increase contrast and partially darken the specimen field.  
           [0024]    Although reference is made in the above text to a surgical microscope, the invention is not limited thereto but rather is also available to other users of optical devices having additional illumination systems (e.g. video and photographic cameras, microscopes for circuit-board use, etc.).  
           [0025]    The Parts List and FIGS. 1 through 4 are, together with the subject matter described in the claims, integral constituents of the disclosure of this Application.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    The invention is described in more detail, by way of example, with reference to schematic depictions. In the drawings:  
         [0027]    [0027]FIG. 1 schematically depicts the entire microscope assemblage with the use of a deflection element according to the present invention;  
         [0028]    [0028]FIG. 2 a  is a plan view of the deflection element (deflection mirror) depicted in FIG. 1 in the main beam path of a stereoscopic surgical microscope;  
         [0029]    [0029]FIG. 2 b  schematically depicts a system for reflecting illumination into the observation beam path of a surgical microscope;  
         [0030]    [0030]FIGS. 3 a - c  show the manner of operation of the reflecting-in system in selected and enlarged detail;  
         [0031]    [0031]FIGS. 4 a, b  show a stop for partial light reduction of the illumination beam path. 
     
    
       [0032]    The Figures are described in interconnected and overlapping fashion. Identical reference characters denote identical components; reference characters having different indices indicate functionally identical components.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    [0033]FIG. 1 schematically depicts the entire microscope assemblage with a system for reflecting illumination into the main beam path of a stereomicroscope, having a deflection element  1  whose diameter exceeds the spacing of the two observation beam paths  3   a,    3   b;  having a main objective  4 ; having a zoom  11 ; having an illumination beam path  5 ; having an illuminating optical system  6 ; having a light source  7 ; having a stop  8 , with an optional electronic control system  9 , that is shiftable in the radial direction; and having a specimen  10 . Also depicted are the arrangement of a zoom  11  (eyepiece/eyepieces), and the axes of observation beam paths  13  and of observer  14 .  
         [0034]    [0034]FIG. 2 a  shows, in plan view, deflection element  1  (depicted in FIG. 1) in the main beam path of a microscope, having two openings  2   a,    2   b  for observation beam paths  3 . Section A-A through the two openings  2   a,    2   b  for the observation beam paths in deflection element  1  is depicted schematically in FIG. 1. Section B-B, depicted in FIG. 2 a , shows a side view of the deflection element at right angles to section A-A.  
         [0035]    [0035]FIG. 2 b  schematically shows, similarly to FIG. 1, a system for reflecting illumination into observation beam path  3  of a microscope, having a deflection element  1 ; having a main objective  4 ; having a zoom  11 ; having an illumination beam path  5  with axis  5   a;  having an axially displaceable illuminating optical system  6 ; having a radially and axially displaceable stop  12  in illumination beam path  5 ; having a light source  7  of any kind; having a stop  8  that is shiftable in the radial direction, with optional electronic control system  9  (but with no depiction of the drive system, known per se); and having a specimen  10 .  
         [0036]    [0036]FIGS. 3 a - c  show in detail the manner of operation of the system for reflecting in illumination, having deflection element  1 , main objective  4 , axis  5   a  of illumination beam path  5 , stop  8 , and illuminating optical system  6 . FIG. 3 a  shows stop  8  centered with respect to axis  5   a  of illumination beam path  5 . FIGS. 3 b  and  3   c  show decentered stop positions, stop  8  being shifted upward in FIG. 3 b  and downward in FIG. 3 c.    
         [0037]    [0037]FIGS. 4 a  and  4   b  show typical configurations of stops  8  and  12  with light-intensity-reducing regions  8   a,    12   a  and non-light-intensity-reducing regions  8   b,    12   b,  in which context stops  8 ,  12  can have any shape, in particular including one that is not rotationally symmetrical.  
         [0038]    Manner of Operation  
         [0039]    For certain applications, for example when microscopes are used in the medical sector, an illumination beam path  5  is reflected in for specimen field illumination. When a deflection element  1  according to the present invention is used, for example a mirror or deflection prism having two openings  2   a,    2   b  for observation beam paths  3  as shown in FIG. 1 or  2   a,  illumination beam path  5  proceeding from light source  7  is switched into the main beam path of the microscope. Deflection element  1  is configured in such a way that its diameter exceeds the spacing of the two observation beam paths  3 ; and it comprises, for each beam path, openings that can be selectably closed off by means of a partially reflective element.  
         [0040]    The result of using a stop  8  that can be shifted radially with respect to axis  5   a  of illumination beam path  5  is that specimen  10  can be illuminated at different angles.  
         [0041]    If a stop  8  (FIG. 4 b ) having a central light-intensity-reducing region (neutral density filter or spectral filter, LCD, etc.) is used, annular illumination of specimen  10  without shadowing can be achieved. Special illumination profiles can be created by means of stops that are not of rotationally symmetrical configuration.  
         [0042]    By shifting illuminating optical system  6  in the axial direction, it is possible to configure large specimen fields with a small illumination pupil or small specimen fields with a large illumination pupil.  
         [0043]    Instead of stop  8 , a wedge-shaped pair of optical elements, wherein one of the pair of optical elements is rotatable or movable relative to the other, can also be used to shift the illumination beam path in order to shift the axis of the illumination beam path. By “wedge-shaped”, it is meant that a light exit surface of the pair of optical elements is non-parallel to a light entry surface of the pair of optical elements. For example, the pair of optical elements could comprise a pair of prisms or a concave-convex lens pair.  
         [0044]    It is also possible, and a type of embodiment, for the entire illuminating optical system with axis  5   a  to be shifted parallel to the centered position. As a result, the entire illumination pupil remains effective with the corresponding light intensity, even in the shifted state; shifting of stop  8 , on the other hand, means a reduction of the illumination pupil and thus a reduction in intensity.  
         [0045]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.  
       PARTS LIST  
       [0046]    [0046] 1  Deflection element  
         [0047]    [0047] 2  Opening for observation beam path  
         [0048]    [0048] 2   a, b  Openings for observation beam path  
         [0049]    [0049] 3  Observation beam path  
         [0050]    [0050] 4  Main objective  
         [0051]    [0051] 5  Illumination beam path  
         [0052]    [0052] 5   a  Axis of illumination beam path  
         [0053]    [0053] 6  Illuminating optical system  
         [0054]    [0054] 7  Light source  
         [0055]    [0055] 8  Stop  
         [0056]    [0056] 8   a, b  Light-intensity-reducing/non-light-intensity-reducing region  
         [0057]    [0057] 9  Electronic stop control system  
         [0058]    [0058] 10  Specimen  
         [0059]    [0059] 11  Zoom  
         [0060]    [0060] 12  Stop  
         [0061]    [0061] 12   a, b  Light-intensity-reducing/non-light-intensity-reducing region  
         [0062]    [0062] 13  Axes of observation beam paths  
         [0063]    [0063] 14  Observer  
         [0064]    A Section A-A  
         [0065]    B Section B-B