Abstract:
A Vibration damping device for a microscope comprises a housing. In the housing a foam rubber defining a cavity is formed which encloses a weight. The foam rubber has a plurality of interconnected pores. The housing is of the vibration damping device has in one embodiment a rectangular shape.

Description:
FIELD OF THE INVENTION 
     The present invention refers to a vibration damping device for microscopes especially the invention relates to a vibration damping device for confocal scanning microscopes and confocal laser scanning microscopes. 
     BACKGROUND OF THE INVENTION 
     It is vital for all the microscopic application that the distance between the objective and the object is constant during image capture. Vibration may cause a non-constant distance during image capture which may result in a reduced image quality. Vibration is a great inhibitor of microscope performance and it becomes a greater problem as the expected magnification and desired image quality increase, being particularly sensitive in the field of confocal laser scanning microscopy. At the threshold of the problem are vibrations which derive from the environment, such as footsteps, power applications, vehicles and other movements in the vicinity. It is assumed that suitable isolation means has been provided to reduce the effect of such vibrations on the microscope base or the table a microscope rests on. There remain, nonetheless, inherent vibrations, i.e., those deriving from devices built in the microscope itself, for example, electric motors, fans and other dynamics of microscope accessories. 
     The prior art provides several solution for the reduction of vibrations in microscope stands or in special elements of the whole microscope. U.S. Pat. 4,168,881 by Harold E. Rosenberger et. al., granted Sep. 25, 1979, discloses a construction of a microscope stand which reduces vibration effects. Here the objective mount is isolated from the superstructure. The microscope stage is mounted upon the pillar by means chosen to lend the stage a large measure of the pillar&#39;s rigidity. The stage has a relatively wide, vertical span of mounting bearings in contact with the pillar and the interface is relatively low on the pillar. The objective lens is also mounted in rigid relation to the pillar, by a strong cantilever arm rising at a low angle from the pillar and stoutly and rigidly held on the pillar. The eyepiece lens, or other viewing apparatus, is mounted on an arm, also cantilevered from the pillar, which extends over and around the objective mounting arm but which does not touch it anywhere. When the microscopist, or a bystander, touches the eyepiece mounting arm or the superstructure, vibrations and deflections which he might thereby introduce are to a large extent absorbed by the eyepiece mounting arm before they can be transmitted to the pillar or through it to the objective or stage mounts An introduced complexity in structure enables the reduction of vibrations. 
     U.S. Pat. No. 5,764,409 by James B. Colvin, entitled: ELIMINATION OF VIBRATION BY VIBRATION COUPLING IN MICROSCOPY APPLICATIONS, granted Jun. 09, 1998 shows a base for the microscope being placed over an opening in the wafer sorter. A translational apparatus is attached to the base for lowering a charge coupled device camera into an opening in the wafer sorter. A compact housing containing microscope optics is coupled to the camera. A vibration reducing apparatus is coupled to the microscope optics for preventing movement of the camera relative to the chip. 
     U.S. Pat. No. 5,731,896 by Hans Baumann et. al. entitled: MICROSCOPE, granted Mar. 24, 1998 shows a microscope which has the optically imaging portion of its optical arrangement separated from the object to be observed. The microscope has at least one force exerting drive element for the compensation of vibrations acting on the optical arrangement from its surroundings in at least one direction perpendicular to the optical axis. The drive element is installed in or on the microscope. The elimination of vibrations requires complicated control electronics and increases the cost of a microscope. 
     An additional vibration preventing device for a microscope is disclosed in the JP-Patent Application JP10148235. The disclosed device generates a noise which supplies an acoustic wave of reverse phase to this noise, which is for example generated in the sample chamber. The two kinds of sounds are negated each other. Vibration is remarkably reduced. Again, the system requires a complicated set-up to achieve the elimination of the vibrations. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to provide means which effectively reduce the inherent vibrations of a microscope. 
     The aforesaid object is achieved by vibration damping device for a microscope comprising a piece of foam rubber and a weight attached to said piece of foam rubber. 
     It is an other object of the invention to provide a microscope which allows, despite the inherent vibrations of the microscope, the capturing of high quality images 
     This object is achieved by a microscope comprising a stand, at least one focusing device movably mounted to the stand, and a vibration damping device attached to at least one focusing device. 
     What has been recognized according to the present invention is firstly that by mechanically coupling the vibration damping device to a movable part of a microscope, the inherent vibrations and vibrations induced by external sources are reduced efficiently. The external sources for example are: air condition, fans used for external electronic devices, airplanes, vibrations of the building etc. The inherent vibrations arouse from electromotors and/or mechanical gears mounted in the stand of the microscope. The stage and/or the objective is moved by the electromotors along the optical axis in order to focus on one sample plane. Once the focus on the selected sample plane is achieved it is vital for the capturing of high quality images that the focus stays at this plane during the whole image capturing process. The vibration damping device is coupled to the stage and/or the objective to minimize the effect of the inherent vibrations on the constant focus during image capture. 
     It has proven advantageous that the housing of the vibration damping device is attached directly to the part of the microscope of which the vibrations should be reduced. To achieve a efficient vibration damping the vibration damping device need to be mechanically coupled to the part of the microscope which requires the damping. It is advantageous as well to attach the foam rubber with the mounted weight to the part of the microscope which requires damping. Consequently, the housing is not necessary to achieve the damping effect. It provides a better appearance of the whole vibration damping device and does not allow any manipulations of the vibration damping device. 
     The present invention is advantageous since with the vibration damping device a significant reduction of the vibrations is achieved. This enables that the image capture is done in one single plane of the object and is not disturbed by vibrations caused for example by the electromotor for moving the stage or the electromotor for moving the objective. The movement for the stage and the objective is along the optical axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In conjunction with the explanation of the preferred exemplary embodiments with reference to the drawings, a general explanation is also given of preferred embodiments and developments of the teaching. In the drawings: 
     FIG. 1 shows, in a schematic cross section along the longitudinal axis of the vibration damping device; 
     FIG. 2 shows, in a schematic cross section along an axis perpendicular to the longitudinal axis of the vibration damping device 
     FIG. 3 shows a first embodiment of the mounting of the vibration damping device to a microscope, and 
     FIG. 4 shows a second embodiment of the mounting of the vibration damping device to a microscope. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 each show a vibration damping  1  device of the present invention. The vibration damping device  1  (FIG. 1) defines a longitudinal axis  2 . The vibration damping device  1  comprises a rectangular housing  3  which is defined by rigid walls  3   a . A foam rubber  4  is attached to the inside of the walls  3   a . The foam rubber  4  defines a cavity  5  which has in the present embodiment the form of a cylinder. The foam rubber  4  has numerous interconnected pores to let the air, enclosed in said foam rubber  4 , freely move around under the exerted force and thereby dissipate energy in the foam rubber  4 . A material for the foam rubber  4  is for example Neoprene™. The force is exerted by a weight  6  which is placed in the cavity  5 . The cavity  5  loosely holds the weight  6  which is made from a high density material. In order to keep the costs down the material for the weight  6  is made of lead. As a second embodiment of the vibration damping device there is no need for a housing. The foam rubber  4  with an attached weight  6  are mounted directly to the device which requires damping. 
     FIG. 3 shows an upright microscope  7  with an reflection light source  8  and an transmission light source  9  both of which are attached to the microscope stand  10 . The microscope  7  further comprises at least one objective  11  and a condensor  12  which are arranged in an optical axis  13 . An eyepiece  14  is attached to the microscope stand  10  to provide the viewing or observation opportunities of a sample. The sample is paced on a stage  15 . The stage  15 , also facilitating focusing, is movable in the direction of the optical axis  13 . The direction of movement is show by the double arrow S—S in FIG.  3 . Since in most application the stage  15  is moved by an electro motor (not shown), which is mounted inside the stand  10 , vibration are transmitted form the stand  10  to the stage  15 . Not only the electro motor for the stage  15  also other devices mounted inside the stand are responsible for the vibrations of the stage  15 . The stage defines an upper surface  16  adjacent to the objective  11  and lower surface  17  adjacent to the condensor  12 . The vibration damping device  1  is mounted  1  mounted to the lower surface  17  of the stage  15 . Furthermore, it is essential that the vibration damping device  1  is mounted to the stage without influencing the path of the optical axis  13 . 
     FIG. 4 shows a schematic view of a confocal microscope  20 . A laser  30  generates a fine light beam  23 . A sample  21  is placed on a fixed stage  22 . Similar features are designated with the same reference numeral. The sample  21  is illuminated with a fine light beam  23  which directed via a beam splitter  26  to a scanning device  25  and an objective  24 . The objective  24  focuses the light onto the sample  21 . A focusing device is as shown in the embodiment of FIG. 3 the stage  15  and in the embodiment of FIG. 4 the objective  24 . The light beam  23  scans over or through an area of the sample  21 . The scanning motion of the light beam  23  is initiated by the scanning device  25 . Light returning form the sample  21  is transmitted by a beam splitter  26  to at least one detector  27 . A translation of the focus of the illumination light is carried out by a translation of a revolver  28  on which the objectives  24  are arranged. The detailed design of the revolver is disclosed in the German Utility model 299 09 217.8 which is incorporated by reference herein. In order to avoid vibrations the vibration damping device  1  is directly mounted to the revolver  28 . This causes an elimination or a remarkable reduction in the vibrations induced by the movement of the revolver  28 . 
     The vibration damping device  1  of the present invention avoids the occurrence of unintentional movements of the sample and/or the objective. The unintentional movement would cause a remarkable reduction in image quality. 
     In conclusion, be it noted very particularly that the exemplary embodiment set forth above serves merely to describe the teaching claimed, but does not limit it to the exemplary embodiments. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 vibration damping device 
               
               
                 2 
                 longitudinal axis 
               
               
                 3 
                 rectangular housing 
               
               
                 3a 
                 rigid walls 
               
               
                 4 
                 foam rubber 
               
               
                 5 
                 cavity 
               
               
                 6 
                 weight 
               
               
                 7 
                 microscope 
               
               
                 8 
                 reflection light source 
               
               
                 9 
                 transmission light source 
               
               
                 10 
                 stand 
               
               
                 11 
                 objective 
               
               
                 12 
                 condensor 
               
               
                 13 
                 optical axis 
               
               
                 14 
                 mirror 
               
               
                 15 
                 stage 
               
               
                 16 
                 upper surface 
               
               
                 17 
                 lower surface 
               
               
                 20 
                 confocal microscope 
               
               
                 21 
                 sample 
               
               
                 22 
                 fixed stage 
               
               
                 23 
                 light beam 
               
               
                 24 
                 objective 
               
               
                 25 
                 scanning device 
               
               
                 26 
                 beam splitter 
               
               
                 27 
                 detector 
               
               
                 28 
                 revolver 
               
               
                 30 
                 laser 
               
               
                 S-S 
                 double arrow