Abstract:
The present invention broadly comprises a device, such as a slider, for performing phase contrast microscopy, the device containing a plurality of at least three phase contrast annuli. The slider is received into a microscope condenser mounted under a microscope stage and that is adapted to receive the device and align the device such that a phase contrast annulus is aligned with an appropriate microscope objective phase ring. The invention also comprises printed or engraved indicators or other markings indicating whether the bright field aperture or a particular phase contrast annulus is in position in the illumination path of the microscope. The invention further comprises a device for preventing the removal of the device from the condenser.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to microscopy, more specifically to phase contrast microscopy, and, even more particularly, to a multiple phase contrast annulus slider for a microscope. 
     BACKGROUND 
     As is well known, a microscope is an optical instrument used to view, examine and study very small objects. There are many different types of microscopes, each best suited to particular applications. These include compound microscopes, stereomicroscopes, confocal microscopes, inverted microscopes, laser microscopes, fluorescence microscopes and polarizing microscopes, to name but a few. 
     The present invention relates generally to compound microscopes and to those compound microscopes that are equipped to carry out phase contrast microscopy. 
     A variety of removable components are frequently used with compound microscopes to illuminate the object being investigated with diverse types of light. Components of this type include phase rings that create phase shifts in the light illuminating an object being investigated. Phase shifts of this type take advantage of differential diffraction of light as it passes through transparent objects such as single cell organisms to allow objects under study that are invisible under bright field conditions to become visible to the microscope user. This form of microscopy is called phase contrast microscopy. 
     It is well known in the art that in phase contrast microscopy, a pair of phase rings is used to create the phase shift. One ring is usually positioned within the microscope objective at the image plane near the nosepiece, while the other phase ring, commonly called a phase contrast annulus or simply, an annulus, is placed between the light source and the condenser. For each microscope objective having a different magnification, a different phase ring/annulus pair must be placed into the light path. 
     Because the phase rings located on a phase contrast objective are permanently positioned so as to be to be automatically brought into proper alignment in the illumination beam path, there is no difficulty in always selecting the correct objective phase ring for the desired magnification. However, one difficulty created by the necessity of using different pairs of phase rings for different magnifications is the need to change the phase contrast annulus positioned between the light source and the condenser. Because the phase contrast annulus is positioned underneath the microscope stage, it is awkward to determine if the correct annulus is being used for a particular magnification. 
     An additional problem in using phase contrast microscopes is that the phase ring/annulus pair must be changed with each change in magnification. The phase ring is automatically correctly switched when the desired objective is placed into position. However, the annulus is commonly changed by inserting into and removing from the condenser components that hold a single annulus appropriate for the desired magnification. This results in unused phase contrast annuli being exposed in a loose manner at a work station where they can be easily lost or damaged. This is especially true in educational settings in which the user may be an inexperienced student who may be performing a variety of exercises requiring an array of different phase rings in a limited period of time. This problem can also exist in a clinical setting where different tests and procedures may require frequent changes of phase contrast annuli as different magnifications are used. Alternatively, phase contrast annuli may be mounted on a turret attached to a microscope condenser which allows the user to turn the phase ring into position. However, such turret-condenser assemblies are expensive and require a final adjustment of the annulus after it is turned in order to align the annulus with the objective phase contrast ring. 
     Others have disclosed sliders for supporting and positioning components into the illumination path of a compound microscope. Sliders currently exist that either hold two phase contrast annuli or hold a single phase contrast annulus and define a bright field aperture. In addition, U.S. Pat. No. 4,756,611 to Yonekubo, et al. discloses a turret having multiple phase contrast annuli as well as other light altering elements commonly used in light microscopy. U.S. Pat. No. 4,807,980 to Dietrich discloses a condenser with an element that pivots a light filter or similar element into the illumination path of a compound microscope. Only one element is contained in the pivot arm of the &#39;980 patent. U.S. Pat. No. 5,032,011 to Muchel describes a condenser possessing a space that can accept a slider or a turret containing phase contrast rings or other light microscopy components. U.S. Pat. No. 5,371,624 to Nagono, et al. discloses a slider defining a bright field opening and holding two equal size fluorescent light filters used in fluorescent microscopy. 
     None of the above disclosures depict a slider possessing phase contrast annuli for all objectives commonly found on phase contrast microscopes. What is needed then is a device that is capable of holding phase contrast annuli for low, medium and high magnifications typically found on a compound microscope in an educational or clinical setting. Preferably, such a slider will be of such a length as to not extend beyond the outline of the microscope stage while still holding three phase contrast annuli as well as a bright field aperture. In addition, there is a need for a mechanism for removably securing a slider in the condenser while still allowing it to slide freely to position the desired annulus into proper alignment in the illumination beam path. 
     SUMMARY OF INVENTION 
     The present invention broadly comprises a device, such as a slider, for performing phase contrast microscopy, the device containing a plurality of at least three phase contrast annuli. The device is received into a microscope condenser mounted under a microscope stage and that is adapted to receive the device and align one of the phase contrast annuli with the appropriate objective phase ring without the need for a final alignment. 
     The invention also comprises printed or engraved indicators or other markings indicating whether the bright field aperture or a particular phase contrast annulus is in position in the illumination path of the microscope. The invention further comprises a mechanism for preventing the removal of the device from the condenser. 
     A general object of the invention is to provide a device, such as a slider, capable of holding a plurality of at least three phase contrast annuli in addition to a bright field aperture. 
     A second object of the invention is to provide a device capable of holding a bright field aperture with a plurality of at least three phase contrast annuli. 
     An additional object of the invention is to provide a device having a handle to enable easy movement of the device within the condenser. 
     An additional object of the invention is to disclose a device with indicia designating whether a bright field aperture or one of a plurality of phase contrast annuli is positioned in the illumination path of the microscope. 
     A further object of the invention is to disclose a component designed to prevent the device from being removed from the condenser of a compound microscope. 
     A further object of the invention is to provide a device configured to correctly align a phase contrast annulus contained on the device with an appropriate objective phase ring without the use of a final alignment. 
     A still further object of the invention is to minimize the area on a device, such as a slider, needed to hold a plurality of phase contrast annuli. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
     FIG. 1 is a perspective view of a typical compound microscope adaptable for use with the multiple phase contrast annulus slider of the present invention; 
     FIG. 2 is a top view of the multiple annulus slider of the present invention; 
     FIG. 3 is a side view of the multiple annulus slider of the present invention taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a cross-section view of the multiple annulus slider of the present invention taken along line  4 — 4  of FIG. 2; 
     FIGS. 5A-5D are top cross-section views of the multiple annulus slider of the present invention depicting the bright field aperture and each one of the phase contrast annuli in operational position in a condenser with the condenser lens system removed; 
     FIG. 6 is an expanded cross-section view of the phase contrast annuli taken from the indicated area of FIG. 4; 
     FIG. 7 is a top view of the multiple annulus slider inserted into a condenser; 
     FIG. 8 is a fragmentary cross-section of a condenser-multiple annulus slider assembly taken along line  8 — 8  in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is understood that the invention is not limited to the disclosed embodiments. 
     The present invention broadly comprises a microscope assembly including a microscope having a base mounted illuminator, a condenser mounted below the stage of a microscope and having a space to receive a device containing optical elements. In the embodiment shown in FIG. 1, the condenser is adapted to receive a slider. The slider is positioned within the condenser to place one of the optical elements in the illumination path of the microscope. A conventional compound microscope is shown in perspective view in FIG.  1 . Although the invention is suitable for use with a variety of light microscopes, it is useful to review basic microscope structure and function to appreciate the present invention. 
     FIG. 1 illustrates compound microscope  10 . The microscope includes mounting stand  11  which includes base  12  and eyepiece/objective mounting platform  13 . Viewing body  14  is mounted to a top surface of mounting stand  11 . In the embodiment shown, the viewing body is binocular, comprising two eyepieces  15  mounted in eye tubes  29 . The viewing body is not germane to the invention, which is suitable for use with a microscope configured with any type of viewing body (monocular, binocular, trinocular, video, etc.). Objectives  16  are mounted to turret  31 . Turret  31  is rotatably mounted to nosepiece  32 , which in turn is mounted to a bottom surface of mounting stand  11 . The microscope includes stage  18  upon which a specimen to be viewed is placed. Slide mount  19  is incorporated into stage  18  and enables movement of a slide (not shown) holding the specimen to be viewed. Illuminator  25  is mounted in base  12  of microscope  10 . Illuminator  25  provides a controllable source of light to illuminate the specimen as is well known in the art. In the several drawing views of the invention, a critical type illumination is shown, although the invention is suitable for use with other illumination configurations as well. Light from illuminator  25  travels in a beam upwardly through condenser  28 , which functions to gather and focus the light. As described below, slot  29  receives the present invention into condenser  28 . 
     FIG. 2 is a top view of multiple annulus slider  30  of the present invention. Slider  30  defines phase contrast apertures  32 ,  34 , and  36  that are defined by slider  30  and pass through slider  30 . In a preferred embodiment, as seen in FIG. 2, slider  30  further defines bright field aperture  31  which is placed in the illumination beam path when it is desired to use bright field microscopy. Phase contrast aperture  32  supports low magnification annulus  33 . Low magnification annulus  33  is typically used with 10× or 20× objectives. Phase contrast aperture  34  supports medium magnification annulus  35 . Medium magnification annulus  35  is typically used with 40× objectives. Phase contrast aperture  36  supports high magnification annulus  37 . High magnification annulus  37  is typically used with 100× objectives. In a preferred embodiment, as depicted in FIG. 2, phase contrast annuli  33 ,  35 , and  37  are comprised of arcs cut out of support material  33 A,  35 A, and  37 A, respectively, and formed into a circular or ring configuration. Support material  33 A,  35 A, and  37 A is set into and supported by the sides of phase contrast apertures  32 ,  34 , and  36 , respectively. The support material may be blackened brass or other suitable material known in the art. Other annuli suitable for use with phase contrast objectives having different magnifications are well known to those skilled in the art. 
     In a preferred embodiment, phase contrast apertures  32 ,  34 , and  36  will have a width larger than the diameter of the ring or circle configuration of the phase contrast annuli. As seen in FIG. 2, phase contrast apertures  33 ,  35 , and  37  have an elongated shape with a length l in which l is greater than w. Each one of a plurality of phase contrast apertures may have other shapes including rectangles, ellipses, or oblong configurations with the object of minimizing the area within which the plurality of phase contrast apertures are contained. In this preferred embodiment, the formula w&gt;d is used to describe the shape of a phase contrast aperture wherein w is the width of the aperture and d is the diameter of the phase contrast annulus supported by the annulus. 
     Notches  38  are cut into side  39  ot slider  30 . Notches  38  are spaced along side  39  such that they act as guide stops when contacting stop guide rod  48 . (See FIGS. 5A-5D.) The spacing of notches  38  enables bright field aperture  31  or one of annuli  33 ,  35 , and  37  to be positioned correctly within the illumination path of microscope  10 . In a preferred embodiment, handle  41  extends from slider  30  at one end of slider  30 . Handle  41  may be attached to slider  30  using screws, rivets, adhesives or other attachment means known in the art. In a more preferred embodiment, handle  41  is integral with slider  30  as seen in FIG.  2 . In a most preferred embodiment, handle  41  includes pads  42 . Pads  42  are attached to both surfaces of slide  30  and are preferably fabricated from a non heat-conducting material such as plastic. More preferably, pads  42  are shaped such that they prevent slide  30  from being withdrawn completely through slot  29  in condenser  28 . In a preferred embodiment, slider  30  contains an additional mechanism preventing it from being withdrawn from condenser  28 . More preferably the additional mechanism will be removably secured to slider  30 . Most preferably, stop screw  40  is removably secured into side  49  of slider  30  to prevent removal of slider  30  through condenser  28 . Side  49  is inserted into slot  29  of condenser  28  so as to extend through condenser  28 . Stop screw  40  is then removably secured into side  49  of slider  30  to prevent slider  30  from being withdrawn through slot  29 . 
     FIG. 3 shows a side view of slider  30 . One of pads  42  is attached to each surface of handle  41 . Stop screw  40  is shown inserted into slider  30 . Indicators  43 ,  44 ,  45 , and  46  are displayed on side  47  of slider  30 . As described below, indicators  43 ,  44 ,  45 , and  46  indicate to the operator which aperture or annulus is positioned in the illumination beam path. Alternatively, indicators  43 ,  44 ,  45 , and  46  may be placed on the top surface of slider  30  or on the same side as notches  38 . 
     FIG. 4 is a cross-section of slider  30  taken along line  4 — 4  of FIG. 2 depicting the placement of annuli  33 ,  35 , and  37  in phase contrast apertures  32 ,  34 , and  36 , respectively. As can be seen in FIG. 4, the support material  33 A,  35 A, and  37 A is supported within phase contrast apertures  32 ,  34 , and  36 , respectively. The blackened brass or other opaque material from which the annuli are formed is supported using LOCTITE® 369 or other similar adhesive well known to those skilled in the art. Also represented in FIG. 4 is bright field aperture  31 . 
     FIGS. 5A-5D are top views of slider  30  inserted into condenser  28  (with condenser lens section removed) depicting either bright field aperture  31  or one of annuli  33 ,  35 , or  37  placed into the illumination beam path. In FIGS. 5A-5D, it can be seen that the slider-condenser assembly is constructed to realize correct alignment of bright field aperture  31  or any of the phase contrast annuli  33 ,  35 , or  37  when one of notches  38  contacts stop rod  48  inside condenser  28 . Phase contrast annuli  33 ,  35 , and  37  are spaced in relation to notches  38  to be correctly aligned with the appropriate objective phase ring when one of notches  38  contacts stop rod  48 . The contact between notches  38  and stop rod  48  is configured in such a manner so as to create a noticeable stop or resistance to the passage of slider  30 , while still allowing easy movement of a different notch  38  to stop rod  48  to align a different annulus. As can be seen in FIGS. 5A-5D, different notches  38  contact stop rod  48  to align annuli  33 ,  35 , or  37  as well as bright field aperture  31 . It is evident that the irregular spacing of notches  38  is necessary to correctly align bright field aperture  31  and phase contrast apertures  32 ,  34 , and  36  in the illumination beam path as bright field aperture  31  and phase contrast apertures  32 ,  34 , and  36  all differ from each other in width or diameter. As seen in FIG. 3, indicators  43 ,  44 ,  45 , and  46  are irregularly spaced on side  47  of slider  30  so as to indicate which of the elements on slider  30  is positioned in the illumination beam path. In a preferred embodiment, as seen in FIG. 8, the visible indicator just emerging from condenser  28  indicates which element on slider  30  is in position in the illumination beam path. 
     FIG. 6 is a magnified cross section of the annuli depicted in FIG.  4 . As can be seen in FIG. 6, annuli  33 ,  35 , and  37  are openings defined by support material  33 A,  35 A, and  37 A, respectively. Such support material may be fabricated from brass blackened by using an anodizing process to apply a semi-flat black coating. Other suitable materials and/or processes known in the art may also be used. 
     FIG. 7 is a top view of slider  30  inserted into condenser  28 . FIG. 8 is a fragmentary cross-section of condenser  28  taken along line  8 — 8  in FIG.  7 . Condenser  28  receives slider  30  through slot  29 . Phase contrast aperture  36  and support material  37 A are shown positioned in the illumination beam path under lenses  50  and  51 . The position of slider  30  as seen in FIG. 8 is the same as shown in FIG. 5D in which phase contrast annulus  37  is aligned in the illumination path of microscope  10 . It can be seen that pads  42  extend above and below the entrance to slot  29  thus preventing slider  30  from being pushed further into or through condenser  28 , while stop screw  40  prevents withdrawal of slider  30  from the opposite direction. FIG. 8 depicts a preferred embodiment in which indicator  46 , which indicates phase contrast annulus  37  is in positioned in the illumination beam path, is the indicator closest to condenser  28 . 
     Thus it is seen that the objects of the invention are efficiently obtained, although changes and modifications to the invention should be readily apparent to those having ordinary skill in the art, which changes are considered to be within the scope of the invention as claimed. For example, although the invention is shown in combination with a binocular compound microscope, it should be appreciated that the invention is suitable for use with a variety of compound microscopes types and with other optical instruments and devices, such as for example, devices used in photomicrography. Also, in the embodiments of the invention. shown, bright field aperture  31  and phase contrast annuli  33 ,  35 , and  37  may be positioned on slider  30  in a different order than shown above. In addition, as stated above, the apertures or other mounts supporting the phase contrast annuli may have different shapes.