Abstract:
A microscope illumination system provides light for both transmitted and vertical microscopy techniques. A transmitted light illuminator comprises a collector lens system, a zoom lens system, and a collimator lens system which direct the light from a source to the microscope condenser. The vertical illumination system utilizes the same light source and comprises a collimator lens system, a relay lens system, and a collector lens system which provides the light directed into the rear of the microscope objective by a beam splitter.

Description:
This is a division of application Ser. No. 607,842 filed Aug. 25, 1975. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a microscope illumination system, and more particularly, to an illumination system capable of providing light for transmitted as well as vertical microscopy techniques utilizing the Kohler method of illumination. 
     It is an object of the present invention to provide Kohler illumination for standard 4X through 100X objectives. 
     It is a further object of the present invention to provide transmitted light illumination using objectives of 4X to 100 X without using special lenses. 
     It is a still further object of the present invention to provide an illumination system for vertical or transmitted light having lateral color-free imaging of the field iris. 
     It is another object of the present invention to provide Kohler illumination in the vertical light mode for standard 10X through 100X objectives. 
     It is still another object of the present invention to provide Kohler illumination in either the vertical or transmitted light modes of a microscope having up to a 24 mm field. 
     Prior art illumination systems frequently required the use of additional lenses commonly referred to as &#34;throw-in&#34; lenses in order to accommodate transmitted light objectives from 4X to 100X. Also, prior art illumination systems for microscopes intended to be used with either vertical or transmitted light illumination, usually required separate sources of illumination. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION AND DRAWINGS 
     The present invention avoids the use of throw-in lenses in transmitted light Kohler illumination systems by using a special zoom unit which permits filling both the field iris as well as the back aperture diaphram of the condenser simultaneously throughout the required range of adjustment for objectives ranging from 4X to 100X. The zoom unit offers one advantage in providing most efficient use of the illumination source for each objective rather than comprising on each of a plurality of objectives. Also, it is possible to use the illumination system of the present invention in both the transmitted light and vertical light modes simultaneously since each mode uses a different side of the filament. 
     FIG. 1 is an optical diagram of both the transmitted and vertical illumination systems viewed transverse to the optical axis thereof; 
     FIG. 2 is an optical diagram of the transmitted light portion of the illumination system in detail; 
     FIG. 3 is an optical diagram of an alternate collector lens system; and 
     FIG. 4 is an optical diagram of the vertical light portion of the illumination system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a transmitted light system T collects light from filament 1 in a collector lens system X, which is then directed along an optical axis to zoom system XI. The light continues along the optical axis through field iris 2, through collimating system XII to the back aperture 3 of condenser 4 to object 0. An aperture diaphram is usually positioned in the condenser back aperture 3 to permit the microscopist to adjust the intensity of illumination. Field iris 2 is used by the microscopist to adjust the area illuminated to suit a chosen objective. It is usually desirable to use a deflector 5 in oder to reduce the size of a microscope base which would otherwise be required. 
     The vertical illumination portion V has a collector lens system XIII which collects light from the back of filament 1 and directs the same along an optical axis to relay lens system XIV, through aperture diaphram 6 and field iris 7 to collimator XV, which provides the light for the microscope objective 8 utilizing beam splitter 9. It is usually desirable to utilize a prism 10 and beam deflector 11 in order to utilize filament 1 instead of requiring an additional light source. 
     Referring to FIG. 2, collector X comprises a concavo-convex positive singlet 20, and a double convex positive singlet 21. The rearmost surface of singlet 21 is aspheric. Zoom system XI has a convex-plano positive singlet 22, and a plano-convex positive singlet 23. The collimator lens system XII comprises a double convex positive doublet 24, and a double convex positive singlet 25. With respect to lens parameters of the transmitted light illumination system, the axial thicknesses of successive lens elements are designated T1 to T7, and the axial spaces from the filament plane FO are designated S1 to S8. The successive lens radii are designated R1 to R13, wherein the minus sign (-) applies to surfaces whose center of curvature lies on the filament side of their vertices. The refraction indices and Abbe numbers of the glasses are designated ND(1) to ND(7) and ν(1) to ν(7), respectively. 
     Since the numerical aperture in size of the light in the object 0 is directly proportional to the focal length F, in millimeters, of condenser 4, the lens parameters in the following Table I are a function of F, which can typically vary from 9 mm to 12 mm. 
     
                                           TABLE I__________________________________________________________________________                            Index of  AbbeLens   Radius (R)       Thickness (T)                Spacing (S) Refraction (ND)                                      No. (ν)__________________________________________________________________________                S.sub.1=                   0.64633F   R.sub.1 =-3.38335F20          T.sub.1 =0.48536F    ND.sub.1 =1.523                                      ν.sub.1 =58.60   R.sub.2 =0.82730F                S.sub.2=                   0.02585F   R.sub.3 =2.23395F21          T.sub.2 =0.62048F    ND.sub.2 =1.523                                      ν.sub.2 =58.60   R.sub.4 =-0.99343F                S.sub.3=                   1.5253F(4X)                   3.0765F(10X)                   5.5584F(100X)   R.sub.5 =1.3940F22          T.sub.3 =0.41365F    ND.sub.3 =1.523                                      ν.sub.3 =58.60   R.sub.6= ∞                S.sub.4=                   0.72389F   R.sub.7= ∞23          T.sub.4 =0.41365F    ND.sub.4 =1.523                                      ν.sub.4 =58.60   R.sub.8 =-1.6546F                S.sub.5=                   5.8169F(4X)                   4.2658F(10X)                   1.7839F(100X)                S.sub.6=                   1.03413F   R.sub.9 =10.8635F       T.sub.5 =0.77559F    ND.sub.5 =1.786                                      ν.sub.5 =25.5224 R.sub.10 =3.9555F       T.sub.6 =2.06825F    ND.sub.6 =1.588                                      ν.sub.6 =61.19   R.sub.11 =-5.01551F                S.sub.7=                   5.37746F   R.sub.12 =5.14478F25          T.sub.7 =1.24095F    ND.sub.7 =1.498 ν.sub.7 =66.94   R.sub.13 =-24.8263F                S.sub.8=                   6.72182__________________________________________________________________________ 
    
     Wherein F is in millimeters. The back surface of singlet 21 with radius R 4 , is an axially symmetrical aspheric surface with Z axis of revolution. The value of Z for any given value of x and y and is defined by the equation: 
     
         Z= cp.sup.2 /[ 1+ √1- (k+ 1)c.sup.2 p.sup.2 ] + dp.sup.4 + ep.sup.6 + fp.sup.8 + gp.sup.10 
    
     wherein: 
      d= 0.181924× 10 -   3   
      e= -0.361616× 10 -   5   
      f= 0.943675× 10 -   7   
      g= 0.743223× 10 -   9   
      p 2=  ]x 2+  y 2   
      c= 1/R.sub. 4 and 
      k= 1.0 
     The mathematical support for this formula and explanation may be found in the Military Standard Handbook, MIL-HBDK-141 (50CT62), Sec. 5.5.1, Page 5-13 to 5-21. 
     Numerically stated, the preferred embodiment of the invention when the condenser has a focal length of 9.67 mm, has the following relationship. 
     
                       TABLE II______________________________________Lens Radius (R)  Thickness (T)                         Spacing (S)______________________________________                         S.sub.1=                              6.25R.sub.1 =32.71720               T.sub.1 =4.500R.sub.2 =-8.000                         S.sub.2=                              0.25R.sub.3 =21.60321               T.sub.2 =6.000R.sub.4 =-9.6065*                         S.sub.3=                              14.75 (4X)                              29.75 (10X)                              53.75 (100X) - R.sub.5 =13.48022               T.sub.3 =4.000R.sub.6=∞                         S.sub.4 =                              7.000R.sub.7= ∞23               T.sub.4 =4.000R.sub.8 =-16.000                         S.sub.5=                              56.25 (4X)                              41.25 (10X)                              17.25 (100X)                         S.sub.6=                              10.000R.sub.9 =105.050            T.sub.5 =7.50024   R.sub.10 =38.250             T.sub.6 =20.000R.sub.11 =-48.500                         S.sub.7=                              52.000R.sub.12 =49.75025                T.sub.7 =12.000R.sub.13 =-240.070                         S.sub.8=                              65.000______________________________________ *A conic coefficient and four aspheric deformation coefficients above. 
    
     Referring to FIG. 3, alternate collector XA has a plano-convex positive singlet 26 as the first element. As the second element, the collector has a plano-convex positive singlet 27, and the last element is a double convex positive singlet 28. The rearmost surface of 27 and foremost surface of 28 are aspheric surfaces. 
     The magnification of collector groups X and XA is substantially the same (3X); however, collector group XA has a higher numerical aperture providing a larger filament image at back aperture plane 3 for a given field size at object plane O. With respect to lens parameters of the transmitted light illumination system, the axial thicknesses of successive lens elements are designated T101 to T103, and the axial spaces from the filament plane FO are designated S100  to S103.  The successive lens radii are designated R101  to R106,  wherein the minus sign (-) applies to surfaces whose center of curvature lies on the filament side of their vertices. The refraction indices and Abbe numbers of the glasses are designated ND(101) to ND(103) and ν(101) to ν(103), respectively. 
     
                                           TABLE III__________________________________________________________________________                               Index of  AbbeLens   Radius (R)        Thickness (T)                 Spacing (S)   Refraction (ND)                                         No. (ν)__________________________________________________________________________                 S.sub.100=                      0.5171F   R.sub.101= ∞26           T.sub.101 =0.5171F     ND.sub.101 =1.523                                         ν.sub.101 =58.60   R.sub.102 =-0.9486F                 S.sub.101=                      0.0103F   R.sub.103= ∞27           T.sub.102 =0.5688F     ND.sub.102 =1.523                                         ν.sub.102 =58.60   R.sub.104 =-1.15669F*                 S.sub.102=                      0.0103F   R.sub.105 =1.61446F**28           T.sub.103 =0.5688F     ND.sub.103 =1.523                                         ν.sub.103 =58.60   R.sub.106 =-12.7564F                 S.sub.103=                      1.0910F(4X)                      2.6422F(10X)                      5.1241F(100X)*Associated with R.sub.104 is a conic coefficient k=-0.99341 and fourasphericdeformation coefficients:d = -0.50246 × 10.sup..sup.-4e = - 0.43451 × 10.sup..sup.-5f = 0.11169 × 10.sup..sup.-6g = -0.57450 × 10.sup..sup.-9**Associated with R.sub.105 is a conic coefficient k =-0.9817 and fourasphericdeformation coefficients:d = -0.59858 × 10.sup..sup.-4e = -0.44852 × 10.sup..sup.-5f = 0.10981 × 10.sup..sup.-6g = -0.60834 × 10.sup..sup.-9__________________________________________________________________________ 
    
     A preferred embodiment of the alternate collector system using a condenser focal length of 9.67 mm has the following specific values. 
     
                       TABLE IV______________________________________Lens Radius (R)   Thickness (T)                        Spacing (S)______________________________________                        S.sub.100=                             5.00R.sub.101= ∞26                T.sub.101 =5.00R.sub.102 =-9.173                        S.sub.101=                             0.100R.sub.103= ∞27                T.sub.102 =5.50R.sub.104 =-11.185*                        S.sub.102=                             0.100R.sub.105 =15.612**28                T.sub.103 =5.50R.sub.10 =-123.354                        S.sub.103=                             10.550 (4X)                             25.550 (10X)                             49.550 (100X)______________________________________ *Coefficients appear above in Table III. **Coefficients appear above in Table III. 
    
     The vertical illumination portion of the illumination system is more clearly shown in FIG. 4. Light from the backside of filament 1 is preferably deflected by prism 10 to collector XIII, which directs the light through relay system XIV to collimator XV, thence to beam splitter 9 and objective 8. Collector lens system XIII has, as the first element, a plano-convex positive singlet 29, and a plano-convex positive singlet 30. The relay lens system contains a double convex positive singlet 31, and a convex-plano positive singlet 32, which provides a magnified image of filament 1 to aperture diaphram 12. 
     After imaging the filament at aperture diaphram 12, the light passes through field iris 13 to collimator 33. Collimating lens 33 is a double convex positive doublet which re-images the filament near the back image plane (shoulder of objective 8) and an image of field iris 13 substantially at infinity. Prism 10 and deflector 11 in conjunction with beam splitter 9, are used to fold the optical system to minimize space and provide a convenient optical path for association with a micro cope. 
     With respect to lens parameters of the transmitted light illumination system, the axial thicknesses of successive lens elements are designated T201 to T207, and the axial spaces from the filament plane FO are designated S201 to S209. The successive lens radii are designated R201 to R211, wherein the minus sign(-) applies to surfaces whose center of curvature lies on the filament side of their vertices. The refraction indices and Abbe numbers of the glasses are designated ND(201) to ND(207) and ν(201) and ν(207), respectively. 
     
                                           TABLE V__________________________________________________________________________                         Index of  AbbeLens   Radius (R)        Thickness (T)                 Spacing (S)                         Refraction (N.sub.D)                                   No. (ν)__________________________________________________________________________                 S.sub.201 =0.5688Q        T.sub.201 =1.2410Q                         ND.sub.201 =1.69963                                   ν.sub.201 =34.67                 S.sub.202 =0.0000Q   R.sub.201 =∞29           T.sub.202 =0.2585Q                         ND.sub.202 =1.58904                                   ν.sub.202 =61.23   R.sub.202 =-1.3005Q                 S.sub.203 =1.2410Q   R.sub.203 =∞30           T.sub.203 =0.2585Q                         ND.sub.203 =1.58904                                   ν.sub.203 =61.23   R.sub.204 =-3.3739Q                 S.sub.204 =14.5605Q   R.sub.205 =11.2289Q31           T.sub.204 =0.5171Q                         ND.sub.204 =1.52300                                   ν.sub.204 =58.60   R.sub.206 =-11.2289Q                 S.sub.205 =9.7248Q   R.sub.207 =4.0384Q32           T.sub.205 =0.3619Q                         ND.sub.205 =1.52300                                   ν.sub.205 =58.60   R.sub.208=  ∞                 S.sub.206 =0.5336Q                 S.sub.207 =5.5843Q                 S.sub.208 =4.7043Q   R.sub.209 =7.8283Q        T.sub.206 =0.2585Q                         ND.sub.206 =1.78600                                   ν.sub.206 =25.5233 R.sub.210 =4.0384Q        T.sub.207 =0.5171Q                         ND.sub.207 =1.58904                                   ν.sub.207 =61.23   R.sub.211 =-4.0384Q                 S.sub.209 =9.2036Q__________________________________________________________________________ 
    
     Wherein Q is equal to 9 mm to 15 mm. 
     A preferred embodiment of the vertical illumination system wherein Q is equal to 9.67 mm is given by the following values. 
     
                       TABLE VI______________________________________Lens Radius (R)    Thickness (T) Spacing (S)______________________________________                            S.sub.201 =5.50               T.sub.201 =12.00                            S.sub.202 =0.00R.sub.201 =∞29                 T.sub.202 =2.50R.sub.202 =-12.576                            S.sub.203 =12.00R.sub.203 =∞30                 T.sub.203 =2.50R.sub.204 =-32.6255                            S.sub.204 =140.80R.sub.205 =108.58331                 T.sub.204 =5.00R.sub.206 =108.583                            S.sub.209 =94.04R.sub.207 =39.05132                 T.sub.205 =3.50R.sub.208 =∞                            S.sub.206 =5.16                            S.sub.207 =54.00                            S.sub.208 =45.50R.sub.209 =75.700              T.sub.206 =2.5033   R.sub.210 =39.051              T.sub.207 =5.00R.sub.211 =-39.051                            S.sub.209 =89.00______________________________________ 
    
     In the foregoing designs, particularly in the specific embodiments, a filament size of at least 2 mm× 1 mm is necessary to assure that the image of the filament extends entirely across the opening defined by the aperture diaphram 6 and/or 12.