Abstract:
A changing apparatus for a microscope ( 10 ) comprises a carrying body ( 50, 150, 250, 350 ) supported rotatably around a rotation axis (R), having a first coupling part ( 52 ), and at least one optical element ( 100, 200, 300, 400 ) having a second coupling part ( 102 ) that is couplable to the first coupling part ( 52 ) for releasable mounting of the optical element ( 100, 200, 300, 400 ) on the carrying body ( 50, 150, 250, 350 ). The first coupling part ( 52 ) comprises a first mechanical coding structure ( 56 ) and the second coupling part ( 102 ) comprises a second mechanical coding structure ( 104 ) that, in a predetermined installation alignment toward the first coding structure ( 56 ), is complementary thereto and, in that installation alignment, is placeable onto the first coding structure ( 56 ) perpendicularly to the rotation axis (R) of the carrying body ( 50, 150, 250, 350 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of German patent application number 10 2011 051 949.1 filed Jul. 19, 2011, the entire disclosure of which is incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a changing apparatus for a microscope, comprising a carrying body supported rotatably around a rotation axis, the carrying body having a first coupling part, and at least one optical element having a second coupling part that is couplable to the first coupling part for releasable mounting of the optical element on the carrying body. 
       BACKGROUND OF THE INVENTION 
       [0003]    Changing apparatuses of the kind recited above are used in microscopes as retainers for selectable attachment of optical elements, e.g. fluorescence filter blocks. Reference is made in this connection, by way of example, to DE 199 36 497 A1, which discloses a changing apparatus in which the optical elements to be mounted on a carrying body are each equipped with a dovetail slide that is installed on an abutting surface of the carrying body. Attached in front of the abutting surface, as interacting retainer components, are a peg-shaped bolt and, next to the latter, a compression spring bent away under tension by the bolt. As a result of the tension of the bent compression spring, the latter and the bolt are pressed onto the inner sides of the dovetail slide pushed against the abutting surface. 
         [0004]    This previously known changing apparatus is disadvantageous in that the respective optical element, with its dovetail slide, must be clamped onto the spring structure, constituted from the bolt and the compression spring, from the side, i.e. in a direction that is substantially parallel to the abutting surface of the carrying body. For this reason the carrying body must be immobilized, for example by means of a brake provided expressly therefor, in order for the optical elements to be coupled on, so as to prevent an undesired rotary motion of the carrying body that complicates installation. In addition, with the spring structure recited above, the deflection of the compression spring must be precisely adjusted in order to achieve the desired clamping effect in the installed state. 
         [0005]    From documents DE 199 24 686 A1 and US 2008/0043324 A1 changing apparatuses are known which respectively include a carrying body, supported rotatably around a rotation axis. An optical element can be releasably mounted on the carrying body. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the invention is to describe a simply constructed changing apparatus for a microscope that enables secure retention and precise positioning of optical elements, and simple changing of said elements. 
         [0007]    The invention achieves this object by way of a changing apparatus for a microscope having the features according to claim  1 . 
         [0008]    The changing apparatus according to the present invention is notable for the fact that the first coupling part comprises a first mechanical coding structure and the second coupling part comprises a second mechanical coding structure that, in a predetermined installation alignment toward the first coding structure, is embodied in a manner complementary thereto and, in that installation alignment, is placeable onto the first coding structure perpendicularly to the rotation axis of the carrying body. 
         [0009]    The invention thus provides, on the coupling parts, mechanical coding structures which are embodied in mutually complementary fashion in such a way that they can be coupled to one another only in a predetermined installation alignment with respect to each other. The coding structures are embodied so that they enable placement of the second coding structure (provided on the optical element) onto the first coding structure (provided on the carrying body) perpendicularly to the rotation axis of the carrying body, i.e. in a radial direction. A “complementary” structure is to be understood in this context as a solid physical configuration that brings about a mutual three-dimensional fit, in the manner of a lock-and-key principle, in the desired installation alignment and in a radial direction perpendicularly to the rotation axis of the carrying body. The complementary coding structures thus produce an interface geometry that ensures unambiguous positioning of the optical element on the carrying body and avoids incorrect installation. 
         [0010]    The coding structures allow the user to simply place the optical element in a radial direction onto the carrying body. This considerably simplifies handling of the changing apparatus as compared with the approach known from the existing art, in which the optical element is clamped in place on the carrying body from the side. In particular, it is no longer necessary to immobilize the carrying body, for example, by means of a brake, or secure it with a screw, in order to install the optical element, since installation forces acting rotationally on the carrying body are avoided by placing the optical element radially onto the carrying body. “Installation” of the optical element is therefore understood hereinafter as attachment or placement of the optical element on the carrying body, including in particular without the use of tools. 
         [0011]    As a result of the radially complementary coding structures, the optical element is also effectively secured against centrifugal forces that occur upon acceleration or deceleration of the carrying body when it rotates around the rotation axis. 
         [0012]    One of the two coding structures comprises at least one first engagement element, e.g. a peg and/or an elongated projection, while the respective other coding structure comprises at least one second engagement element complementary thereto, e.g. a recess and/or a groove, that can be brought into engagement with the first engagement element perpendicularly to the rotation axis of the carrying body. The result of these elements that engage with one another is that the optical element can be installed in simple fashion on the carrying body, and is securely held on it. 
         [0013]    Alternatively or in addition to the engagement elements recited above, in a further advantageous embodiment one of the two coding structures comprises at least one first planar abutting element and the respective other coding structure at least one second planar abutting element complementary thereto, which can be brought into abutment with the first abutting element perpendicularly to the rotation axis of the carrying body. Especially when the two coding structures comprise not only elements engaging with one another, such as e.g. a peg and a hole or an elongated projection and a groove, but also abutting elements that are in planar contact, this ensures that on the one hand the coding structures enable simple radial placement of the optical element while avoiding incorrect installation, and on the other hand the optical element is securely held on the carrying body. 
         [0014]    The engagement elements that engage into one another in pairs, and/or the abutting elements that abut against one another in pairs, define a three-point support. A three-point support of this kind unequivocally defines, i.e. neither overdetermines nor underdetermines, an installation plane that ensures secure mounting of the optical element on the carrying body. 
         [0015]    If grooves are provided as engagement elements, they are preferably embodied rectangularly or triangularly in cross section. Such so-called U- or V-grooves, respectively, ensure reliable coupling of the optical element onto the carrying body. V-grooves in particular, because of their cross-sectional shape tapering to a point, promote self-alignment of the optical element on the carrying body. 
         [0016]    In a preferred embodiment, at least two grooves are provided, of which a first groove, preferably rectangular in cross section, extends parallel to the rotation axis of the carrying body, and a second groove, preferably triangular in cross section, extends transversely to the first groove. Thanks to the elements that engage into one another in pairs and are arranged transversely to one another, this embodiment promotes secure retention of the optical element on the carrying body. 
         [0017]    The second groove is preferably a groove interrupted by the first groove, while the second projection is embodied as a bar-shaped element that passes through the first projection in a transverse direction. In this embodiment, the two grooves are in a sense arranged crosswise with respect to one another, which further promotes self-aligning mounting of the optical element on the carrying body. 
         [0018]    Preferably the first coding structure comprises at least one first connecting element, and the second coding structure comprises at least one second connecting element, which can be detachably brought into mutual contact, i.e. can be coupled, for coupling of the two coding structures. In a preferred embodiment, the connecting elements are each embodied on one of the engagement elements that can be brought into mutual engagement and/or on one of the abutting elements that can be brought into mutual abutment. For example, one of the two connecting elements is embodied on a bottom surface of the groove that is rectangular in cross section, and the other connecting element on a flat end surface, facing toward said bottom surface, of the projection engaging into the groove. This ensures particularly secure retention of the optical element on the carrying body. 
         [0019]    The first connecting element and the second connecting preferably encompass magnetically attractive elements. For example, a magnet is mounted on the first connecting element, and a ferromagnetic material on the second connecting element. It is also conceivable for both the first connecting element and the second connecting element to encompass mutually attractive magnets, or to be embodied as such. The range of the magnetic attraction force generated between such elements causes the coding elements, brought close to one another upon insertion of the optical element, to be pulled onto one another in self-aligning fashion. This facilitates installation of the optical element on the changing apparatus. Various combinations of magnetically effective elements, i.e. magnets, magnetized or magnetizable elements, are conceivable as connecting elements. For example, permanent magnets and/or elements made of ferrimagnetic or ferromagnetic materials can be used. Electromagnets can also be utilized as connecting elements. 
         [0020]    In an advantageous embodiment, the two abutting elements that can be brought into mutual abutment are each formed from two surfaces arranged at an angle, preferably a right angle, to one another. If one of these surfaces is aligned horizontally in the installation state, it can then serve as a support surface on which the abutting element associated with it rests as a result of gravity. A support surface of this kind can be embodied, for example, at the lower end of the carrying body. 
         [0021]    In a particularly preferred embodiment, the mutually magnetically attractive elements of the coding structures connected to one another are arranged with an offset from one another, and thereby generate a magnetic attraction force that has two force components which each bring about a magnetic attraction between those surfaces of the abutting elements which are brought into mutual abutment. For example, if one of the abutting elements rests on a horizontally arranged support surface, it is then possible, by means of magnetically effective connecting elements offset vertically from each other, to generate an obliquely downwardly directed attraction force that has a horizontal force component and a force component directed vertically downward. The vertically aligned surfaces are then pressed onto one another by the horizontal force component, while the force component directed vertically downward, in addition to gravity that acts in any case, presses the surface resting on the horizontal support surface onto the support surface. 
         [0022]    Instead of magnetically effective connecting elements, connecting elements of other types, e.g. screws, pegs, springs, or the like, can also be used as force-generating means. In a preferred embodiment, for example, the first or the second connecting element encompasses a spring clamp, and the respective other connecting element comprises a latching element that latches into the spring clamp. The spring force acts on the support surfaces of the two abutting elements pressing against one another, and thereby ensures self-aligning contact of the abutting elements against the support surfaces, and thus secure retention of the optical element on the changing apparatus. 
         [0023]    Be it noted that the engagement elements, abutting elements, and connecting elements described above can be used in any combinations, provided assurance is given that coding structures constituted by these elements interact in the manner according to the present invention in order to bring about radial coupling while avoiding incorrect installation, and secure retention of the optical element on the carrying body. The engagement elements, abutting elements, and connecting elements can also be distributed arbitrarily on the carrying body and on the optical element, provided interaction thereof according to the present invention is ensured. In one specific embodiment, for example, a groove can be embodied on the carrying body and a projection, engaging into the groove, can be embodied on the optical element, while in an alternative embodiment the corresponding groove is arranged on the optical element and the projection on the carrying body. 
         [0024]    By preference, the at least one optical element encompasses multiple optical elements each having the second coupling part, and the carrying body encompasses multiple first coupling parts that are each associated with one of the second coupling parts. In this case the carrying body can be populated with multiple optical elements and can be rotated as necessary in the microscope so that one of said optical elements is selectably put into operation. The optical elements can be, for example, fluorescence filter blocks that each contain an excitation filter, a beam splitter, and a blocking filter; the changing apparatus can thus advantageously be used in fluorescence microscopy for alternative selection of a fluorescence region associated with the filter set. 
         [0025]    The carrying body is preferably a turret that is rotationally symmetrical around its rotation axis. In this case the coupling parts arranged on the turret, and also the coupling parts associated with them that are provided on the optical elements, are preferably each of identical design. Each of the optical elements can thus be connected to each of the coupling parts embodied on the turret. 
         [0026]    The invention further provides a microscope having a changing apparatus of the kind described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING VIEWS 
         [0027]    The invention will be described below in further detail with reference to the Figures, in which: 
           [0028]      FIG. 1  schematically depicts a fluorescence microscope in which a changing apparatus corresponding to the invention is arranged; 
           [0029]      FIG. 2  is a perspective view of a turret that is part of a changing apparatus corresponding to the first exemplifying embodiment; 
           [0030]      FIG. 3  is a schematic view of a fluorescence filter block that is part of the changing apparatus corresponding to the first exemplifying embodiment; 
           [0031]      FIG. 4  is a side view of the changing apparatus corresponding to the first exemplifying embodiment, with an optical element fitted on; 
           [0032]      FIG. 5  is a sectioned view of the changing apparatus according to a first exemplifying embodiment, in the installed state; 
           [0033]      FIG. 6  is a perspective view of the changing apparatus according to a first exemplifying embodiment, in the installed state; 
           [0034]      FIG. 7  is a perspective view of a turret that is part of a changing apparatus according to a second exemplifying embodiment; 
           [0035]      FIG. 8  shows a filter block that is part of the changing apparatus according to a second exemplifying embodiment; 
           [0036]      FIG. 9  shows a turret that is part of a changing apparatus according to a third exemplifying embodiment; 
           [0037]      FIG. 10  shows a filter block that is part of the changing apparatus according to a third exemplifying embodiment; 
           [0038]      FIG. 11  is a perspective view of the changing apparatus according to a third exemplifying embodiment, in the installed state; 
           [0039]      FIG. 12  is a sectioned view of the changing apparatus according to a third exemplifying embodiment; 
           [0040]      FIG. 13  is a perspective view of a turret that is part of a changing apparatus according to a fourth exemplifying embodiment; 
           [0041]      FIG. 14  is a perspective view of the changing apparatus according to a fourth exemplifying embodiment, in the installed state; 
           [0042]      FIG. 15  is a plan view of the changing apparatus according to a fourth embodiment, in the installed state; and 
           [0043]      FIG. 16  is a side view of the changing apparatus according to a fourth embodiment, in the installed state. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]      FIG. 1  shows an inverted fluorescence microscope  10  that contains a changing apparatus  12  according to the present invention. The depiction in  FIG. 1  is merely schematic, and is intended only to illustrate the arrangement of changing apparatus  12  in fluorescence microscope  10 . 
         [0045]    Changing apparatus  12  is installed in a stand  14  of fluorescence microscope  10 . It encompasses a carrying body  16 , hereinafter referred to as a “turret,” mounted rotatably around a rotation axis R. Turret  16  is populated with multiple filter blocks  18 , two of which ( 18   a  and  18   b ) are shown in plan view in the depiction according to  FIG. 1 . Turret  16  and filter blocks  18  are described in detail later on in a variety of embodiments. 
         [0046]    Proceeding from a light source  19  is an illumination beam path  21 , which travels through an illumination optic  23  and encounters a fluorescence filter block  18  that includes an excitation filter  24 , a beam splitter  25  arranged at 45° in the illumination beam path, and a blocking filter  26  (also referred to as an “output filter”). The illumination beam passes through excitation filter  24 , and at beam splitter  25  is directed to an objective  22  that is mounted on an objective turret  20 . Objective turret  20  is rotatable around a turret rotation axis T and comprises a second, unpopulated position  27  (shaded gray) for a further objective. Illumination beam path  21  illuminates a sample  28  that is arranged on a microscope stage  29 . 
         [0047]    Changing apparatus  12  serves to pivot one of the filter blocks ( 18   a,    18   b ) selectably into illumination beam path  21 . 
         [0048]    Objective  22  images sample  28  onto a first intermediate image plane  30 . For this, an imaging beam path  39  passes through objective  22 , beam splitter  25 , blocking filter  26 , and a tube lens  31 , and is directed by a first deflection mirror  32  onto first intermediate image plane  30 . The intermediate image is imaged with a transportation optic  33 , which generates no further magnification, via a second deflection mirror  34  and a third deflection mirror  35  onto a second intermediate image plane  36 . The intermediate image can be viewed by a user  37  with an eyepiece  38 . Alternatively, the intermediate image can be directed onto a camera (not shown). 
         [0049]      FIGS. 2 to 5  show a changing apparatus according to a first exemplifying embodiment.  FIGS. 2 and 3  depict the individual components of the changing apparatus, while  FIGS. 4 and 5  show the changing apparatus in the installed state. 
         [0050]    The changing apparatus according to a first exemplifying embodiment encompasses a turret  50 , depicted in  FIG. 2 , that can be populated with six filter blocks, one of which is depicted by way of example, and labeled  100 , in  FIG. 3 . 
         [0051]    Turret  50  comprises six coupling parts  52  of identical design, onto each of which filter block  100  (or other filter blocks of identical design in terms of coupling) can be mounted. The respective coupling part  52  is embodied on lateral surface  54  of turret  50 . 
         [0052]    Coupling part  52  of turret  50  comprises a first mechanical coding structure that is labeled in general as  56  in  FIG. 2 . This first mechanical coding structure  56  has, in the lower half of the coupling part of lateral surface  54 , two groove bases  58  and  60 , in each of which is embodied a V-shaped groove  62  and  64 . Grooves  62  and  64  are oriented in alignment with one another. They can thus also be construed as a single but interrupted groove. Configured at the upper end of lateral surface  54  is a support surface  66  out of which protrudes a peg  68 . A first circular magnet  70  is located approximately at the center of lateral surface  54 . 
         [0053]    As may best be gathered from the depiction according to  FIG. 5 , turret  50  is penetrated by a bearing bore  72 , embodied in stepped fashion, which serves to support turret  50  rotatably on rotation axis R (indicated merely schematically in the Figures). 
         [0054]    Filter block  100 , shown in isolation in  FIG. 3 , has a coupling part  102  associated with coupling part  52  of turret  50 . Said part  102  comprises a second mechanical coding structure, embodied in complementary fashion to first coding structure  56  of turret  50 , labeled in general as  104  in  FIG. 3 . This complementary coding structure  104  is formed in turn from a cuboidal elevation  106  that protrudes from an end surface  108 . Elevation  106  has at its lower end two laterally protruding projections  110 ,  112 , and at its upper end a rectangular recess  114 . A second circular magnet  116  is located approximately at the center of elevation  106 . 
         [0055]    Coding structures  56  and  104  are adapted to one another in such a way that filter block  100  can be placed with its coupling part  102 , in a radial direction perpendicular to rotation axis R, onto coupling part  52  of turret  50 . When filter block  100  is installed on turret  50  in this fashion, i.e. without the use of tools, projection  112  then comes into engagement with groove  62 , projection  110  comes into engagement with groove  64 , the upper part of the end face  108  of elevation  106  comes into abutment with abutting surface  66 , and recess  114  comes into engagement with peg  68 . In addition, the two magnets  70  and  116  come into abutment with one another and generate a magnetic attraction force by which filter block  34  is held fixedly on turret  50 . As indicated by an arrow in  FIG. 5 , this attractive force acts in a radial direction perpendicular to rotation axis R. 
         [0056]    Engagement elements  62 ,  64 , and  68  embodied on turret  50  form, in interaction with engagement elements  110 ,  112 ,  114  embodied on filter block  100 , a three-point support that ensures secure locking of filter block  100  on turret  50 . The attraction force generated by the two magnets  70  and  116  furthermore, upon coupling of filter block  100  onto turret  50 , promotes self-alignment of the mutually associated complementary coding structures  56  and  104 . Readjustment and, in particular, the use of tools are superfluous, since filter block  100  is brought into the optimal position merely by being put in place. 
         [0057]    It is evident from the sectional view according to  FIG. 5 , as a supplement to the depictions according to  FIGS. 2 to 4 , that in the present exemplifying embodiment filter block  100  comprises excitation filter  24 , blocking filter  26 , and beam splitter  25 . 
         [0058]      FIGS. 4 to 6  depict the changing apparatus according to a first exemplifying embodiment in the installed state,  FIG. 4  being a side view and  FIG. 5  a sectioned view. As is apparent in particular from  FIGS. 4 and 5 , in the installed state filter block  100  is placed radially onto turret  50 . 
         [0059]    Further exemplifying embodiments of the changing apparatus according to the present invention will be described below with reference to  FIGS. 7 to 16 . These embodiments differ from the first exemplifying embodiment depicted in  FIGS. 2 to 6  in terms of individual elements of the mutually associated, complementary coding structures. In  FIGS. 7 to 16  as well, the latter are designated in general throughout as  56  and  104 , respectively. In addition, components that correspond to those of the first exemplifying embodiment are labeled with the reference characters already used in the first exemplifying embodiment. These components are not described again hereinafter. 
         [0060]      FIG. 7  shows a turret  150  according to a second exemplifying embodiment, the coding structure  56  of which comprises two V-grooves  152  and  154  that are oriented in alignment with one another in a transverse direction of turret  150 . Between grooves  152  and  154 , coding structure  56  comprises a U-groove  156  that extends parallel to rotation axis R. V-shaped grooves  152  and  154  thus form, in a sense, one groove interrupted by U-shaped groove  156 . A magnet  160  is arranged on a bottom surface  158  of U-shaped groove  156 . 
         [0061]      FIG. 8  shows a filter block  200  that is associated with turret  150  depicted in  FIG. 7 . The mechanical coding structure  104  of filter block  200  comprises a cuboidal lug  202  that engages into U-shaped groove  156  upon coupling of filter block  200  onto turret  150 . Lug  202  is penetrated in a transverse direction by a bar  204  whose opposite end segments  206  and  208  are intended for engagement into V-shaped grooves  152  and  154 . Lug  202  further comprises at its end surface  210  a magnet  212  that, upon coupling of filter block  200  onto turret  150 , comes into abutment with magnet  160  arranged in U-shaped groove  156  and thus ensures secure retention of filter block  200  on turret  150 . Embodied on the underside of lug  202  is a threaded bore  214  into which a locking screw (not shown in  FIG. 8 ) can be inserted in order to immobilize bar  204  on lug  202 . 
         [0062]    In the exemplifying embodiment depicted in  FIGS. 7 and 8 , engagement elements  152 ,  154 ,  206 ,  208  on the one hand, and engagement elements  156 ,  202  on the other hand, are arranged crosswise with respect to one another. The result is that filter block  200  is held particularly securely on turret  150 . 
         [0063]      FIGS. 9 to 12  show a changing apparatus according to a third exemplifying embodiment.  FIG. 9  depicts a turret  250  whose mechanical coding structure  56  encompasses two abutting surfaces  252 ,  254  as well as a peg  256 . Coding structure  56  further comprises, at the lower end of turret  250 , two support surfaces  258  and  260  protruding horizontally from lateral surface  54 . Two magnets  262  and  264 , offset vertically from one another, are furthermore arranged on lateral surface  54 . 
         [0064]      FIG. 10  shows a filter block  300  that is intended for coupling onto turret  250 . The mechanical coding structure  104  of filter block  300  provides an elongated, vertically extending recess  302  that is open toward the upper end of filter block  300 . Coding structure  104  furthermore comprises magnets  304  and  306  offset vertically from one another. 
         [0065]    Upon coupling of filter block  300  onto turret  250 , peg  256  comes into engagement with recess  302 . In addition, abutting surfaces  252  and  254 , which are embodied on lateral surface  54  of turret, come into abutment with parts of the end face, facing toward side wall  54 , of filter block  300 . 
         [0066]    As may be gathered from the depiction according to  FIG. 12 , magnets  262 ,  304  and  264 ,  306  that are associated with one another in pairs are each arranged with a vertical offset from one another. Each pair of magnets  262 ,  304  and  264 ,  306  thus generates a magnetic attraction force that comprises both a horizontally acting force component and a force component acting vertically downward. This is indicated in  FIG. 12  by the arrow pointing obliquely downward. The result of the force components directed vertical downward is that those parts of filter block  250  which are supported on support surfaces  258  and  260  of turret  250  are pressed against support surfaces  258  and  260 . The horizontally directed force components, on the other hand, ensure that those parts of filter block  300  that abut against abutting surfaces  252  and  254  are pushed against abutting surfaces  252  and  254 . Lastly, the horizontally directed components also ensure secure engagement of peg  256  into recess  302 . 
         [0067]      FIGS. 13 to 16  show a fourth exemplifying embodiment of the changing apparatus according to the present invention. This changing apparatus encompasses a turret  350 , shown in isolation in  FIG. 13 , that differs from turret  50  according to the first exemplifying embodiment, depicted in  FIG. 2 , substantially only in that at its upper end it comprises, instead of magnet  70  provided therein, a spring clamp  352  that is constituted from two clamp elements  354  and  356 . The free ends of clamp elements  354  and  356  have mutually facing latching segments  358  and  360  inflected inward in a V-shape. 
         [0068]      FIGS. 14 to 16  show the changing apparatus according to a fourth exemplifying embodiment in the installed state. As is apparent therein, a filter block  400  associated with turret  350  differs from filter block  100  according to a first exemplifying embodiment, depicted in  FIG. 3 , only in that magnet  116  provided therein is replaced by a latching element that is constituted from two projections  404  and  406  that are embodied at the upper end of the cuboidal elevation  106  and protrude to the side. As is most easily gathered from  FIG. 15 , the latching element constituted by projections  404  and  406  latches into spring clamp  352  upon placement of filter block  400  onto turret  350 . 
       PARTS LIST 
       [0000]    
       
         
           
               10  Fluorescence microscope 
               12  Changing apparatus 
               14  Stand 
               16  Turret 
               18 ,  18   a,    18   b  Filter blocks 
               19  Light source 
               20  Objective turret 
               21  Illumination beam path 
               22  Objective 
               23  Illumination optic 
               24  Excitation filter 
               25  Beam splitter 
               26  Blocking filter 
               30  First intermediate image plane 
               31  Tube lens 
               32  Deflection mirror 
               33  Transportation optic 
               34  Deflection mirror 
               35  Deflection mirror 
               36  Second intermediate image plane 
               37  User 
               38  Eyepiece 
               50  Turret 
               52  Coupling part 
               54  Lateral surface 
               56  First mechanical coding structure 
               58 ,  60  Groove bases 
               62 ,  64  V-shaped grooves 
               66  Abutting surface 
               68  Peg 
               70  Magnet 
               100  Filter block 
               102  Coupling part 
               104  Second mechanical coding structure 
               106  Elevation 
               108  End surface 
               110 ,  112  Projections 
               114  Recess 
               116  Magnet 
               150  Turret 
               152 ,  154  V-shaped grooves 
               156  U-shaped groove 
               158  Bottom surface 
               160  Magnet 
               200  Filter block 
               202  Lug 
               204  Bar 
               206 ,  208  End segments 
               210  End surface 
               212  Magnet 
               214  Threaded bore 
               250  Turret 
               252 ,  254  Abutting surfaces 
               256  Peg 
               258 ,  260  Support surfaces 
               263 ,  264  Magnets 
               300  Filter block 
               302  Recess 
               304 ,  306  Magnets 
               350  Turret 
               352  Spring clamp 
               354 ,  356  Clamp elements 
               358 ,  360  Latching segments 
               400  Filter block 
               404 ,  406  Projections