Abstract:
The invention provides a stereoscopic imaging optical system that has a total optical length short enough to be suitable for use in electron image microscopes. The stereoscopic imaging optical system comprises, in order from its object side, one objective lens DB and a plurality of zoom imaging optical systems ZI. Each zoom imaging optical system ZI comprises, in order from its object side, a positive first group G 1 , a negative second group G 2 , an aperture stop AS, a positive third group G 3  and a positive fourth group G 4 . The second group moves for zooming on an optical axis, and the fourth group moves on the optical axis in association with the second group for correcting an image position fluctuation incidental to zooming. Various conditions are satisfied.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a stereoscopic imaging optical system, and more particularly to an optical system for stereomicroscopes such as operating microscopes. 
     A stereomicroscope, because of being capable of having a three-dimensional grasp of a minute area, is used in a variety of fields such as studies, inspections, and operations. 
     A conventional stereomicroscope is of two types: one comprising two independent zoom optical systems for the left eye and the right eye, and another comprising one optical system common to both eyes. 
     The former is typically set forth in Patent Publication 1, and the latter is typically shown in Patent Publication 2. 
     There is also a microscope (electron image microscope) wherein an electronic imaging device is located at an imaging position for a viewing optical system, and a stereoscopic image is viewed through a stereoscopic display device instead of an eyepiece lens. An exemplary optical system for the electron image microscope is typically set forth in Patent Publication 3. 
     A video camera is well known as an electronic imaging apparatus having a zoom optical system. A typical one is shown in Patent Publication 4. 
       FIG. 17  is illustrative of the first example of the prior art stereomicroscope. 
     This stereomicroscope comprises a common objective lens for both eyes, a left-and-right pair of afocal zoom lens systems, a left-and-right pair of afocal relay optical systems and a left-and-right pair of imaging optical system. 
       FIG. 18  is illustrative of the second example of the prior art stereomicroscope. 
     This stereomicroscope comprises a common objective lens for both eyes, an afocal zoom optical system common to both eyes and coaxial with the objective lens, an afocal relay optical system common to both eyes and coaxial with the objective lens and a left-and-right pair of imaging optical systems. 
     Such a conventional stereomicroscope as depicted in  FIG. 17  has a long total optical length on an image side with respect to the objective lens (a distance from the object-side surface of each afocal zoom optical system to the image plane of each imaging optical system) for the following two main reasons.
     1. One reason lies in the optical arrangement per se.   

     This is chiefly because the following constraint conditions are satisfied.
     1-1. Each unit has an independent role.   

     There are distinctive functions: the afocal zoom optical systems are capable of zooming, and the imaging optical systems are capable of imaging.
     1-2 Between the individual units there is an afocal connection.   

     The afocal connection here means that light rays from an axial object point come substantially parallel out of the zoom optical systems, and enter the imaging optical systems. 
     This arrangement has one advantage of easy unit replacement.
     2. Another reason lies in the optical layout involved (inherent in an optical microscope).   

     For an optical stereomicroscope it is required to bring a working space (on an operator side) close to a viewing position (an eyepiece lens) thereby allowing the operator to work easily. To this end the arrangement must be laid out such that an optical path from the objective lens to the eyepiece lens is bent. However, allowing for space for locating optical path-bending prisms or the like would render the optical path longer. 
     Such a conventional stereomicroscope as depicted in  FIG. 18 , too, has a long total optical length on an image side with respect to the objective lens (a distance from the object side surface of the afocal zoom optical system to the image plane of each imaging optical system) for the following two main reasons.
     1. One reason lies in the optical arrangement per se.   

     The afocal relay optical system projects an image from an aperture stop onto near the object side of the afocal zoom optical system to keep low the height of off-axis rays near the objective lens and the afocal zoom optical system. This works in favor of diameter reductions near the objective lens and the afocal zoom optical system. Especially for the type comprising the common afocal zoom optical system for both eyes, the afocal relay optical system works in favor of diameter reductions. 
     However, the afocal relay optical system accounts for a large part of the total optical length. In other words, reducing the size of the afocal relay optical system is effective for reductions of the total optical length.
     2. Another reason lies in the optical layout involved (inherent in the optical microscope).   

     Like such a conventional stereomicroscope as depicted in  FIG. 17 , there is a constraint condition for optical path bending. 
     In Patent Publication 3, there is an electron image microscope set forth, in which an entrance pupil position is located between an objective optical system and an object (subject) to keep good perspective. There is nothing disclosed about the possibility of size reductions incidental upon electronization. 
     In Patent Publication 4, there is an optical system for video cameras set forth, which is a 2D optical system for taking one image per one object, not that for stereoscopic imaging. There is nothing stated about a possible application to a stereomicroscope for stereoscopic viewing. 
     If a stereomicroscope is designed for electronic imaging, there is then none of the constraints of the aforesaid optical layout. The electron image microscope gives relative freedom to the relative position between working space (on the operator side) and the viewing position (stereoscopic display device). The electron image microscope with an electronic imaging device located at an imaging position is designed to convert an optical image into electric signals for displaying it on the stereoscopic display device. Between an imaging system and a display system there is an electric connection that enables the stereoscopic display device to be located at a free position. To have an optical system fit for the electron image microscope, it is important to reconsider the optical arrangement per se while taking the above merits (lifting off the constraint conditions) into account. 
     Patent Publication 1: JP(A) 2004-109487 
     Patent Publication 2: JP(A) 10-282428 
     Patent Publication 3: JP(A) 2006-158452 
     Patent Publication 4: JP(A) 2000-206407 
     SUMMARY OF THE INVENTION 
     Having been made in view of such problems with the prior art, the present invention has for its object to provide a stereoscope imaging optical system that has a total optical length enough short to be fit for an electron image microscope. 
     According to the invention, the above object is accomplishable by the provision of a stereoscopic imaging optical system comprising, in order from its object side, one objective lens and a plurality of zoom imaging optical systems, characterized in that: 
     each of said zoom imaging optical systems comprises, in order from its object side, a positive first group, a negative second group, an aperture stop, a positive third group and a positive fourth group, wherein: 
     said second group moves on an optical axis for zooming, 
     said fourth group moves on the optical axis in association with said second group for correcting an image position fluctuation incidental on zooming, and 
     the following conditions are satisfied:
 
−1 &lt;mg   rw &lt;−0.2  (1)
 
−0.4&lt;Δ G4 /Δ G2 &lt;0.4  (2)
 
where mg rw  is the imaging magnification at a low zoom ratio end of the whole of the groups on an image side with respect to the aperture stop,
 
     Δ G4  is a difference in an optical axis direction between the position of the fourth group at a low zoom ratio end and the position of the fourth group at a high zoom ratio end provided that + is on the image side, and 
     Δ G2  is a difference in an optical axis direction between the position of the second group at a low zoom ratio end and the position of the second group at a high zoom ratio end provided that + is on the image side. 
     Referring to how the stereoscopic imaging optical system works, it is most effective for the conventional optical system of the above first type to reduce the size of the zoom optical system. In the above first conventional example, as described above, 1-1. each unit has an independent role, and 1-2. there is an afocal connection between the individual units. For those reasons, the total optical length grows long. 
     In the invention, the four lens groups have an integrally combined zoom and imaging function, and take on a one unit form as a whole. Referring to the refracting power profile here, the first and second groups on the object side with respect to the aperture stop have generally negative refracting power, and after passing through the third group, light is in a substantially afocal state, and imaged at the fourth group. Main zooming is implemented by moving the second group on the optical axis, and correction of an image position in association with zooming is implemented at the fourth group. 
     The aperture stop is located between the second and the third group so that the height of off-axis rays passing through the zoom optical system can be lowered. A space on the object side with respect to the aperture stop is mainly used only for the movement of the second group, while spaces before and after the fourth group are used for correction of the image position in association with zooming. This ensures good zooming efficiency, and works in favor of reducing the total length. 
     In addition, it is preferable for size reductions to satisfy the above conditions (1) and (2). 
     Condition (1) defines the imaging magnification at low zoom ratio end of the whole of the group located on the image side with respect to the aperture stop. 
     As the upper limit of −0.2 to Condition (1) is exceeded, it causes zooming efficiency to go worse, working against size reductions. As the lower limit of −1 to Condition (1) is not reached, it may work for zooming but against aberration correction. 
     Condition (2) defines the amount-of-movement ratio between the second group and the fourth group that move during zooming. As the upper limit of 0.4 to condition (2) is exceeded, it causes the fourth group to be likely to interfere with an optical member near the image plane position at a high zoom ratio end. As the lower limit of −0.4 to Condition (2) is not reached, it causes the fourth group to be likely to interfere with the third group at a high zoom ratio end. As there are deviations from the upper and lower limits of Condition (2), it causes zooming efficiency to go worse, working against size reductions. 
     The invention has a main advantage of shortening the length of the optical system on the image side with respect to the objective lens. 
     Besides, the invention has some other advantages. 
     The invention works for reducing the diameter of the optical system and designing the optical system as a wide-angle arrangement. This is because the aperture stop is located at the center of the zoom imaging optical system as described above, so that the height of off-axis rays passing through the zoom optical system can be lowered. 
     The invention is suited for an electronic imaging device. On the image side with respect to the aperture stop there are the positive third group and the positive fourth group: there is a substantially telecentric arrangement achieved on the image side. This ensures that the angle of incidence of rays onto the electronic imaging device is much the same at the center and periphery of the associated screen. 
     The invention works for mechanical arrangements. Moving parts are the second and the fourth group that are separate from each other so that they are less likely to interfere with each other. 
     In the invention, it is possible to leave out the afocal relay system. In other words, the afocal relay system may be located in conformity to the layout of the microscope body whenever necessary. 
     In a preferable embodiment of the invention, there is a stereoscopic imaging optical system provided which comprises, in order from its object side, one objective lens and a plurality of zoom imaging optical systems, wherein: 
     said objective lens comprises a negative front group and a positive rear group; 
     said zoom imaging optical system comprises, in order from its object side, a positive first group, a negative second group, an aperture stop, a positive third group and a positive fourth group; 
     any one of the front and the rear group in said objective lens moves on an optical axis to implement focusing for changing a working distance, said second group of said zoom imaging optical system moves on the optical axis for zooming, and said fourth group moves on the optical axis in association with said second group to correct an image position fluctuation in association with zooming; and 
     the following conditions (1) and (2) are satisfied:
 
−1 &lt;mg   rw &lt;−0.2  (1)
 
−0.4&lt;Δ G4 /Δ G2 &lt;0.4  (2)
 
where mg rw  is the imaging magnification at a low zoom end of the whole of the groups on an image side with respect to the aperture stop,
 
     Δ G4  is a difference in an optical axis direction between the position of the fourth group at a low zoom ration end and the position of the fourth group at a high zoom ratio end provided that + is on the image side, and 
     Δ G2  is a difference in an optical axis direction between the position of the second group at a low zoom ratio end and the position of the second group at a high zoom ratio end provided that + is on the image side. 
     With the inventive stereoscopic imaging optical system, focusing for changing a working distance (WD) is implemented by the common objective lens for both eyes located nearest to the object side. When an optical system for a sub-viewer is added to that for a main viewer, a total of three or four zoom optical systems must be provided. If focusing is implemented by the common objective lens for both eyes, it is then possible to simplify the mechanical arrangement and control involved. 
     Because the objective lens is on the object side of the zoom optical system, the amount of movement of the lens is not dependent on a zoom position. Given the WD determined, the amount of movement may be same from the low to the high zoom ratio end. Further, the mechanical arrangement and control involved can be simplified. 
     According to a more preferable embodiment of the invention, there is a stereoscopic imaging optical system provided which comprises, in order from its object side, one objective lens and a plurality of zoom imaging optical systems, characterized in that: 
     said objective lens comprises a negative front group and a positive rear group; and 
     each of said zoom imaging optical systems comprises, in order from its object side, a positive first group, a negative second group, an aperture stop, a positive third group and a positive fourth group, wherein: 
     any one group in said objective lens moves on an optical axis to implement focusing for changing a working distance; 
     said second group of each zoom imaging optical system moves on the optical axis for zooming; 
     said fourth group of each zoom imaging optical system moves on the optical axis in association with said second group for correction of an image position fluctuation incidental to zooming; and 
     the following conditions (1′) and (2′) are satisfied:
 
−0.6 &lt;mg   rw &lt;−0.3  (1′)
 
−0.1&lt;Δ G4 /Δ G2 &lt;0.3  (2′)
 
where mg rw  is the imaging magnification at a low zoom end of the whole of the groups on an image side with respect to the aperture stop,
 
     Δ G4  is a difference in an optical axis direction between the position of the fourth group at a low zoom ratio end and the position of the fourth group at a high zoom ratio end provided that + is on the image side, and 
     Δ G2  is a difference in an optical axis direction between the position of the second group at a low zoom ratio end and the position of the second group at a high zoom ratio end provided that + is on the image side. 
     For the above arrangement, it is more preferable that the lower and upper limits of Condition (1) should be −0.6 and −0.3 (Condition (1′)), respectively, and the lower and upper limits of Condition (2) should be 0.1 and 0.3 (Condition (2′)), respectively. 
     In the above embodiments of the invention, the number of the zoom optical systems is not limited to 2: it may be three or more. The reason is that, as described in conjunction with the function of the above objective lens, there is an occasion where an optical system for the sub-viewer is added to that for the main viewer, there is an occasion where an optical path for special light imaging is added to that for visible light imaging, etc. 
     The present invention also provides a stereoscopic imaging optical system comprising, in order from its object side, one objective lens, one afocal zoom optical system, one afocal relay optical system, a plurality of aperture stops, and a plurality of imaging optical systems, characterized in that: 
     said afocal relay optical system comprises a front group and a rear group; 
     there is an intermediate image between said front group and said rear group; and 
     the following condition (3) is satisfied:
 
0.5 &lt;f   F   /L   Z &lt;0.9  (3)
 
where f F  is the focal length of the front group in the afocal relay optical system, and
 
     L Z  is the maximum value of a distance from the surface located nearest to the object side to the surface located nearest to the image side of the afocal zoom optical system. 
     Reference is now made to how this stereoscopic imaging optical system works. For the above second type of conventional optical system having a common afocal zoom optical system for both eyes, the afocal relay optical system is effective for diameter reductions, and should not be left out. In other words, it is most important for the above second type of conventional optical system to reduce the size of the afocal relay optical system. 
     With reference to  FIG. 19  (that is the same as the prior art example of  FIG. 18 ), consider here what is constructed of the afocal relay optical system. Optical length may be approximated by the following formula:
 
 L   P ≅(2· f   F )+(2 ·f   R )
 
where L P  is the optical length of the afocal relay optical system (that is a distance from the aperture stop to an image from the aperture stop),
 
     f F  is the focal length of the front group in the afocal relay optical system, and 
     f R  is the focal length of the rear group in the afocal relay system. 
     To make the optical length L P  of the afocal relay optical system short, it is required to set f F  and f R  at right values. 
     It is desired that the value of f F  be a bit smaller than the length of the afocal zoom optical system (a factor of 0.5 to 0.9). 
     As the lower limit of 0.5 to Condition (3) is not reached, there is a shortage of pupil projection distance, which may otherwise result in an increase in the diameter of the zoom optical system and objective lens. As the upper limit of 0.9 to Condition (3) is exceeded, the pupil projection distance is in excess, resulting in an increase in the total optical length. 
     A chief advantage of the invention is that the length of the optical system can be shortened. 
     The front group in the afocal relay optical system can have the minimum necessary focal length so that the distance (2·f F ) up to an intermediate imaging plane can be shortened (the right side, first term of L P ≅(2·f F )+(2·f R ) 
     Further, the present invention provides a stereoscopic imaging optical system comprising, in order from its object side, one objective lens, one afocal zoom optical system, one afocal relay optical system, a plurality of aperture stops, and a plurality of imaging optical systems, characterized in that: 
     said afocal relay optical system comprises a front group and a rear group; 
     there is an intermediate image between said front group and said rear group; and 
     the following condition (4) is satisfied:
 
1.1 &lt;f   F   /f   R &lt;2  (4)
 
where f F  is the focal length of the front group in the afocal relay optical system, and
 
     f R  is the focal length of the rear group in the afocal relay optical system. 
     Referring to the function of this stereoscopic imaging optical system, there is another way of shortening the optical length of the afocal relay optical system. It is then desired that the value of f R  be smaller than that of f F  (by a factor of 1/1.1 to 1/2) thereby shortening the optical length of re-forming an image at the front group in the afocal relay optical system. 
     As the lower limit of 1.1 to Condition (4) is not reached, there is an increase in the total optical length, and as the upper limit of 2 to Condition (4) is exceeded, it causes the left and right two imaging optical systems to be likely to interfere. 
     A chief advantage of the invention here is that the afocal relay rear group can have the minimum necessary focal length so that the distance (2·f R ) from the intermediate imaging plane to the aperture stops can be shortened (the right side, second term of L P ≅(2·f F )+(2·f R ) 
     Other advantage is that the diameter of the stereoscopic imaging optical system near the imaging optical systems can be made small. 
     This is because f F /f R  is greater than 1 so that the diameter of a center beam can be reduced on the image side. 
     Yet further, the present invention provides a stereoscopic imaging optical system comprising, in order from its object side, one objective lens, one afocal zoom optical system, one afocal relay optical system, a plurality of aperture stops, and a plurality of imaging optical systems, characterized in that: 
     said afocal relay optical system comprises a front group and a rear group; 
     there is an intermediate image between said front group and said rear group; and 
     the following conditions (3) and (4) are satisfied:
 
0.5 &lt;f   F   /L   Z &lt;0.9  (3)
 
1.1 &lt;f   F   /f   R &lt;2  (4)
 
where f F  is the focal length of the front group in the afocal relay optical system,
 
     f R  is the focal length of the rear group in the afocal relay optical system, and 
     L Z  is the maximum value of a distance from the surface nearest to the object side to the surface nearest to the image side of the afocal zoom optical system. 
     More preferably in the invention, the above conditions (3) and (4) should be satisfied at the same time. 
     Still further, the present invention provides a stereoscopic imaging optical system comprising, in order from its object side, one objective lens, one afocal zoom optical system, one afocal relay optical system, a plurality of aperture stops, and a plurality of imaging optical systems, characterized in that: 
     said afocal relay optical system comprises a front group and a rear group; 
     there is an intermediate image between said front group and said rear group; and 
     the following conditions (3), (4) and (5) are satisfied:
 
0.5 &lt;f   F   /L   Z &lt;0.9  (3)
 
1.1 &lt;f   F   /f   R &lt;2  (4)
 
5 &lt;fm/IH&lt; 16  (5)
 
where f F  is the focal length of the front group in the afocal relay optical system,
 
     f R  is the focal length of the rear group in the afocal relay optical system, 
     L Z  is the maximum value of a distance from the surface nearest to the object side to the surface nearest to the image side of the afocal zoom optical system, 
     fm is the focal length of each imaging optical system, and 
     IH is the maximum image height on an imaging device located at an image position of the imaging optical system. 
     The stereoscopic imaging optical system here should better satisfy Condition (5) that is concerned with size reductions of the imaging optical systems, and defines the focal length of the imaging optical systems and the size of the imaging device (the maximum image height). 
     As the upper limit of 16 to Condition (5) is exceeded, the optical length of the imaging optical systems grows long, and as the lower limit of 5 to Condition (5) is not reached, it works against correction of aberrations of the imaging optical systems. 
     Still further, the present invention provides a stereoscopic imaging optical system comprising, in order from its object side, one objective lens, one afocal zoom optical system, one afocal relay optical system, a plurality of aperture stops, and a plurality of imaging optical systems, characterized in that: 
     said afocal relay optical system comprises a front group and a rear group; 
     there is an intermediate image between said front group and said rear group; and 
     the following conditions (3′), (4′) and (5′) are satisfied:
 
0.6 &lt;f   F   /L   Z &lt;0.9  (3′)
 
1.1 &lt;f   F   /f   R &lt;1.8  (4′)
 
7 &lt;fm/IH&lt; 15  (5′)
 
where f F  is the focal length of the front group in the afocal relay optical system,
 
     f R  is the focal length of the rear group in the afocal relay optical system, 
     L Z  is the maximum value of a distance from the surface nearest to the object side to the surface nearest to the image side of the afocal zoom optical system, 
     fm is the focal length of each imaging optical system, and 
     IH is the maximum image height on an imaging device located at an image position of the imaging optical system. 
     More preferably in the invention, the lower and upper limits of Condition (3) should be 0.6 and 0.9 (Condition (3′)), respectively; the lower and upper limits of Condition (4) should be 1.1 and 1.8 (Condition (4′)), respectively; and the lower and upper limits of Condition (5) should be 7 and 15 (Condition (5′)), respectively. 
     In the above embodiments of the invention, the number of the zoom optical systems is not limited to 2, and may be three or more. The reason is that, as described in conjunction with the function of the above objective lens, there is an occasion where an optical system for the sub-viewer is added to that for the main viewer, there is an occasion where an optical path for special light imaging is added to that for visible light imaging, etc. 
     It is noted that the invention also includes an operating microscope having any one of the above stereoscopic imaging optical systems. 
     According to the invention, it is thus possible to provide a stereoscopic imaging optical system that has a total optical length enough short to be well fit for an electron image microscope. 
     Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. 
     The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the constitution hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 1 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
         FIG. 2  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 1 upon zooming at a low zoom ratio while at (a) WD=200 mm, (b) WD=100 mm and (c) WD=400 mm. 
         FIG. 3  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 2 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ration and (b) a high zoom ratio (c) while at a working distance (WD) of 200 mm. 
         FIG. 4  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 3 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
         FIG. 5  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 4 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm 
         FIG. 6  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 4 upon zooming at a low zoom ration while at (a) WD=200 mm, (b) WD=100 mm and (c) WD=400 mm. 
         FIG. 7  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 5 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
         FIG. 8  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 6 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
         FIG. 9  is indicative of spherical aberrations, astigmatism, chromatic aberration of magnification, and distortion of Example 1 in the states of  FIGS. 1(   a ),  1 ( b ) and  1 ( c ). 
         FIG. 10  is indicative of spherical aberrations, astigmatism, chromatic aberration of magnification, and distortion of Example 1 in the states of  FIGS. 2(   a ),  2 ( b ) and  2 ( c ). 
         FIG. 11  is indicative of aberrations of Example 2, as in  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 3(   a ),  3 ( b ) and  3 ( c ). 
         FIG. 12  is indicative of aberrations of Example 3, as in  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 4(   a ),  4 ( b ) and  4 ( c ). 
         FIG. 13  is indicative of aberrations of Example 4, as in  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 5(   a ),  5 ( b ) and  5 ( c ). 
         FIG. 14  is indicative of aberrations of Example 4, as in  FIGS. 10(   a ),  10 ( b ) and  10 ( c ) corresponding to  FIGS. 6(   a ),  6 ( b ) and  6 ( c ). 
         FIG. 15  is indicative of aberrations of Example 5, as in  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 7(   a ),  7 ( b ) and  7 ( c ). 
         FIG. 16  is indicative of aberrations of Example 6, as in  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 8(   a ),  8 ( b ) and  8 ( c ). 
         FIG. 17  is illustrative in lens arrangement section of the first example of the optical system for a conventional stereomicroscope. 
         FIG. 18  is illustrative in lens arrangement section of the second example of the optical system for a conventional stereomicroscope. 
         FIG. 19  is a view that is provided to consider what is constructed of the afocal relay optical system with reference to  FIG. 18 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The inventive stereoscopic imaging optical system is now explained with reference to Examples 1 to 6. 
     In the lens arrangement sections of the stereoscopic imaging optical systems of Examples 1-6, the objective lens system is indicated by OB, the zoom imaging optical system by ZI, the afocal zoom optical system by AZ, the afocal relay optical system by AL, the front and rear groups in the afocal relay optical system by GF and GR, respectively, the imaging optical system by IL, the intermediate image by IM, the end cover glass by FG, optical members (plane-parallel plates), for which infrared cut filters, optical low-pass filters, dichroic mirrors or the like are presumed, by FT, the CCD chip sealing glass by CG, the aperture stop by AS, the flare stop by FS, and the imaging plane (image plane) by IP.Out of these lens arrangement sections, surface numbers of optical surfaces and surface-to-surface spaces are omitted for the purpose of simplifying illustrations. 
     In Examples 1-6, sapphire is used as the material of the end cover glass FG but, of course, other materials resistant to sterilization may be used. Alternatively, general optical glasses may be used as well. 
     Numerical data about Examples 1-6 will be given later. It is here noted that the optical surface numbers are given by Nos. as counted from the front surface of the end cover glass FG, and that the radius of curvature, the surface-to-surface spaces or air spaces, the d-line refractive index, and the Abbe constants are indicated by “r”, “d”, “nd”, and “vd”, respectively. The radius of curvature, and the surface-to-surface space is given in mm. 
       FIG. 1  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 1 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm, and  FIG. 2  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 1 upon zooming at a low zoom ratio while at (a) WD=200 mm, (b) WD=100 mm and (c) WD=400 mm. Throughout the drawings, for the left-and-right pair components, only one is shown, and a center beam at the center of the screen and a chief ray at the periphery of the screen are only shown. 
     Example 1 is made up of the objective lens optical system OB common to both eyes, and a left-and-right pair of zoom imaging optical systems ZI subsequent to it. Each zoom imaging optical system ZI is made up of a positive first group G 1 , a negative second group G 2 , the aperture stop AS, a positive third group G 3 , and a positive fourth group G 4 . Upon zooming from a low to a high zoom ratio, the first group G 1 , the aperture stop AS and the third group G 3  remain fixed, while the second group G 2  moves monotonously toward the image plane side, and the fourth group G 4  first moves toward the object side and then goes back to the image plane side. At the high zoom ration, the fourth group is positioned more on the image plane side than at the low zoom ratio. See  FIG. 1 . 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. See  FIG. 2 . 
     Referring here to the numerical data given later, Surface Nos.  1  and  2  are the end cover glass FG, Surface Nos.  3 - 5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  6 - 8  are the cemented lens in the rear group in the objective lens optical system OB, Surface Nos.  9 - 10  are the double-convex positive lens in the rear group in the objective lens optical system OB, and Surface Nos.  11  through  31  are the zoom imaging optical system ZI. The first group G 1  in the zoom imaging optical system ZI is made up of a double-convex positive lens indicated by Surface Nos.  11  and  12 , and a cemented lens of a double-convex positive lens and a double-concave negative lens indicated by Surface Nos.  13 ,  14  and  15 , and the second group G 2  is made up of a negative meniscus lens convex on its image plane side, indicated by Surface Nos.  16  and  17  and a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 . The aperture stop AS of Surface No.  21  is followed by the third group G 3  that is made up of a double-convex positive lens indicated by Surface Nos.  22  and  23  and a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens indicated by Surface Nos.  24 ,  25  and  26 , and the fourth group G 4  is made up of a cemented lens of a double-concave negative lens and a double-convex positive lens indicated by Surface Nos.  27 ,  28  and  29 . Following this, the optical member (plane-parallel plate) FT indicated by Surface Nos.  30  and  31  is positioned, after which there is the imaging plane (image plane) IP of Surface No.  34  positioned that has the CCD chip sealing glass CG indicated by Surface Nos.  32  and  33 . 
     It should here be noted that a portion from the zoom imaging optical system ZI to the imaging plane IP is decentered 10.5000 mm in the vertical direction to the optical axis of the objective lens optical system OB. 
     The aberration diagrams of this example are presented in  FIGS. 9 and 10 .  FIGS. 9(   a ),  9 ( b ) and  9 ( c ), and  FIGS. 10(   a ),  10 ( b ) and  10 ( c ) are indicative of spherical aberrations, astigmatisms, chromatic aberrations of magnification and distortions in the states of  FIGS. 1(   a ),  1 ( b ) and  1 ( c ), and  FIGS. 2(   a ),  2 ( b ) and  2 ( c ), respectively. Throughout the drawings, the scale is given by length in mm, the proportion (distortion) is given in %, the wavelength is given in nm, the solid line and broken line for astigmatisms are ΔS and ΔM, respectively, and the image height is indicated by FIY. 
       FIG. 3  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 2 upon zooming at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
     Example 2 is made up of the objective lens optical system OB common to both eyes, and a left-and-right pair of zoom imaging optical systems ZI subsequent to it. Each zoom imaging optical system ZI is made up of a positive first group G 1 , a negative second group G 2 , the aperture stop AS, a positive third group G 3 , and a positive fourth group G 4 . Upon zooming from a low to a high zoom ratio, the first group G 1 , the aperture stop AS and the third group G 3  remain fixed, while the second group G 2  moves monotonously toward the image plane side, and the fourth group G 4  first moves toward the object side and then goes back to the image plane side. At the high zoom ratio, the fourth group is positioned more on the image plane side than at the low zoom ratio. 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a double-convex positive lens and a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. 
     Referring here to the numerical data given later, Surface Nos.  1  and  2  are the end cover glass FG, Surface Nos.  3 ,  4  and  5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  6  and  7  are the double-convex positive lens in the rear group in the objective lens optical system OB, Surface Nos.  8 ,  9  and  10  are the cemented lens in the rear group in the objective lens optical system OB, and Surface Nos.  11  through  31  are the zoom imaging optical system ZI. The first group G 1  in the zoom imaging optical system ZI is made up of a double-convex positive lens indicated by Surface Nos.  11  and  12 , and a cemented lens of a double-convex positive lens and a double-concave negative lens indicated by Surface Nos.  13 ,  14  and  15 , and the second group G 2  is made up of a negative meniscus lens convex on its object side, indicated by Surface Nos.  16  and  17  and a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 . The aperture stop AS of Surface No.  21  followed by the third group G 3  that is made up of a double-convex positive lens of Surface Nos.  22 - 23  and a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens indicated by Surface Nos.  24 ,  25  and  26 , and the fourth group G 4  is made up of a cemented lens of a double-concave negative lens and a double-convex positive lens indicated by Surface Nos.  27 ,  28  and  20 . Following this, the optical member (plane-parallel plate) FT of Surface Nos.  30  and  31  is positioned, after which there is the imaging plane (image plane) IP of Surface No.  34  positioned that has the CCD chip sealing glass CG indicated by Surface Nos.  32  and  33 . 
     It should here be noted that a portion from the zoom imaging optical system ZI to the imaging plane IP is decentered 10.5000 mm in the vertical direction to the optical axis of the objective lens optical system OB. 
     Aberration diagrams of this example similar to  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 3(   a ),  3 ( b ) and  3 ( c ) are presented in  FIGS. 11(   a ),  11 ( b ) and  11 ( c ). 
       FIG. 4  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 3 at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. 
     Example 3 is made up of the objective lens optical system OB common to both eyes, and a left-and-right pair of zoom imaging optical systems ZI subsequent to it. Each zoom imaging optical system ZI is made up of a positive first group G 1 , a negative second group G 2 , the aperture stop AS, a positive third group G 3 , and a positive fourth group G 4 . Upon zooming from a low to a high zoom ratio, the first group G 1 , the aperture stop AS and the third group G 3  remain fixed, while the second group G 2  moves monotonously toward the image plane side, and the fourth group G 4  first moves toward the object side and then goes back to the image plane side. At the high zoom ratio, the fourth group is positioned more on the image plane side than at the low zoom ratio. 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. 
     Referring here to the numerical data given later, Surface Nos.  1  and  2  are the end cover glass FG, Surface Nos.  3 ,  4  and  5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  6 ,  7  and  8  are the cemented lens in the rear group in the objective lens optical system OB, Surface Nos.  9  and  10  are the double-convex positive lens in the rear group in the objective lens optical system OB, and Surface Nos.  11  through  31  are the zoom imaging optical system ZI. The first group G 1  in the zoom imaging optical system ZI is made up of a double-convex positive lens indicated by Surface Nos.  11  and  12 , and a cemented lens of a positive meniscus lens convex on its object side and a negative meniscus lens convex on its object side, indicated by Surface Nos.  13 ,  14  and  15 , and the second group G 2  is made up of a negative meniscus lens convex on its object side, indicated by Surface Nos.  16  and  17  and a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 . The aperture stop AS of Surface No.  21  followed by the third group G 3  that is made up of a meniscus lens convex on its image plane side, indicated by Surface Nos.  22  and  23 , and a cemented lens of a double-convex positive lens and a negative meniscus lens convex on its image plane side, indicated by Surface Nos.  24 ,  25  and  26 , and the fourth group G 4  is made up of a cemented lens of a double-concave negative lens and a double-convex positive lens indicated by Surface Nos.  27 ,  28  and  29 . Following this, the optical member (plane-parallel plate) FT indicated by Surface Nos.  30  and  31  is positioned, after which there is the imaging plane (image plane) IP of Surface No.  34  positioned that has the CCD chip sealing glass CG indicated by Surface Nos.  32  and  33 . 
     It should here be noted that a portion from the zoom imaging optical system ZI to the imaging plane IP is decentered 7.5000 mm in the vertical direction to the optical axis of the objective lens optical system OB. 
     Aberration diagrams of this example similar to  FIGS. 9(   a ),  9 ( b ) and  9 ( c ) corresponding to  FIGS. 4(   a ),  4 ( b ) and  4 ( c ) are presented in  FIGS. 12(   a ),  12 ( b ) and  12 ( c ). 
       FIG. 5  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 4 at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm, and  FIG. 6  is illustrative in lens arrangement section of Example 4 at a low zoom ratio while at (a) WD=200 mm, (b) WD=100 mm and (c) WD=400 mm. For a left-and-right pair of components, only one is shown. 
     Example 4 is made up of the objective lens optical system OB common to both eyes, the subsequent afocal zoom optical system AZ and afocal relay optical system AL, and the subsequent left-and-right pair of aperture stops AS and imaging optical systems IL. The afocal zoom optical system AZ is made up of a positive first group G 1 , a negative second group G 2  and a positive third group G 3 , and the afocal relay optical system AL is made up of the positive front group GF and the positive rear group GR with the intermediate image IM held between them. Upon zooming from a low to a high zoom ratio, the first group G 1  in the afocal zoom optical system AZ first moves toward the object side and then goes back to the image plane side, and at the high zoom ratio it is positioned more on the image plane side than at the low zoom ratio. The second group G 2  moves toward the image plane side while the space between it and the first group G 1  grows wide, and the third group G 3  remains fixed. 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. See  FIG. 6 . 
     Referring now to the numerical data given later, Surface Nos.  1  and  2  are the end cover glass FG, Surface Nos.  3 ,  4  and  5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  6 ,  7  and  8  are the cemented lens in the rear group in the objective lens optical system OB, Surface Nos.  9  and  10  are the double-convex positive lens in the rear group in the objective lens optical system OB, Surface No.  11  is the flare stop FS, and Surface Nos.  12  through  23  are the afocal zoom optical system AZ. The first group G 1  in the afocal zoom optical system AZ is made up of a cemented lens of a double-convex positive lens and a negative meniscus lens convex on its image plane side, indicated by Surface Nos.  12 ,  13  and  14 , the second group G 2  is made up of a cemented lens of a cemented lens of a positive meniscus lens convex on its image plane side and a double-concave negative lens, indicated by Surface Nos.  15 ,  16  and  17  and a plano-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 , and the third group G 3  is made up of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, indicated by Surface Nos.  21 ,  22  and  23 . Following this, there are the flare stop FS of Surface No.  24  and the afocal relay optical system AL of Surface Nos.  25  through  39 . The front group GF in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  25  and  26  and a cemented lens of a double-convex positive lens and a double-concave negative lens indicated by Surface Nos.  27 ,  28  and  29 , and Surface No.  32  is the intermediate image IM. The rear group GR in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  33  and  34 , a cemented lens of a double-concave negative lens and a double-convex positive lens indicated by Surface Nos.  35 ,  36  and  37  and a double-convex positive lens of Surface Nos.  38  and  39 . And after the aperture stop AS of Surface No.  40 , there is the imaging optical system IL of Surface Nos.  43  and  44 . The imaging optical system IL is made up of a plane-parallel plate of Surface Nos.  41  and  42 , a positive meniscus lens convex on its object side, indicated by Surface Nos.  43  and  44 , a cemented lens of a double-convex positive lens and a double-concave negative lens indicated by Surface Nos.  45 ,  46  and  47 , and a double-convex positive lens of Surface Nos.  48  and  49 . Following this, there is the optical member (plane-parallel plate) FT of Surface Nos.  50  and  51 , after which there is the imaging plane (image plane) IP of Surface No.  54  positioned that has the CCD chip sealing glass CG indicated by Surface Nos.  52  and  53 . 
     It should here be noted that a portion from the aperture stop AS to the imaging plane IP is decentered 3.000 mm in the vertical direction to the optical axis of the objective lens optical system OB, afocal zoom optical system AZ and afocal relay optical system AL. 
     Aberration diagrams of this example are presented in  FIGS. 13 and 14 .  FIGS. 13(   a ),  13 ( b ) and  13 ( c ), and  FIGS. 14(   a ),  14 ( b ) and  14 ( c ) similar to  FIGS. 9(   a ),  9 ( b ) and  9 ( c ), and  FIGS. 10(   a ),  10 ( b ) and  10 ( c ) are aberration diagrams in the states of  FIGS. 5(   a ),  5 ( b ) and  5 ( c ), and  FIGS. 6(   a ),  6 ( b ) and  6 ( c ), respectively. 
       FIG. 7  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 5 at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio while at a working distance (WD) of 200 mm. For a left-and-right pair of components, only one is shown. 
     Example 5 is made up of the objective lens optical system OB common to both eyes, the subsequent afocal zoom optical system AZ and afocal relay optical system AL, and the subsequent left-and-right pair of aperture stops AS and imaging optical systems IL. The afocal zoom optical system AZ is made up of a positive first group G 1 , a negative second group G 2  and a positive third group G 3 , and the afocal relay optical system AL is made up of the positive front group GF and the positive rear group GR with the intermediate image IM held between them. Upon zooming from a low to a high zoom ratio, the first group G 1  in the afocal zoom optical system AZ first moves toward the object side and then goes back to the image plane side, and at the high zoom ratio it is positioned more on the image plane side than at the low zoom ratio. The second group G 2  moves toward the image plane side while the space between it and the first group G 1  grows wide, and the third group G 3  remains fixed. 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. 
     Referring here to the numerical data given later, Surface Nos.  1  and  2  are the end front cover glass FG, Surface Nos.  3 ,  4  and  5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  6 ,  7  and  8  are the cemented lens in the rear group in the objective lens optical system OB, and Surface Nos.  9  and  10  are the double-convex positive lens in the rear group in the objective lens optical system OB. Surface No.  11  is the flare stop FS followed by the afocal zoom optical system AZ of Surface Nos.  12  through  23 . The first group in the afocal zoom optical system AZ is made up of a cemented lens of a double-convex positive lens and a negative meniscus lens convex on its image plane side, indicated by Surface Nos.  12 ,  13  and  14 , the second group G 2  is made up of a cemented lens of a positive meniscus lens convex on its image plane side and a double-concave negative lens, indicated by Surface Nos.  15 ,  16  and  17  and a cemented lens of a plano-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 , and the third group G 3  is made up of a cemented lens of a negative meniscus lens convex on its object side, indicated by Surface Nos.  21 ,  22  and  23 . Following this, there is the flare stop FS of Surface No.  24  followed by the afocal relay optical system AL indicated by Surface Nos.  25  through  39 . The front group GF in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  25  and  26 , a cemented lens of a double-convex positive lens and a double-concave negative lens, indicated by Surface Nos.  27 ,  28  and  29  and a positive meniscus lens convex on its object side, indicated by Surface Nos.  30  and  31 , with Surface No.  32  indicative of the intermediate image IM. The rear group GR in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  33  and  34 , a cemented lens of a double-concave negative lens and a double-convex positive lens, indicated by Surface Nos.  35 ,  36  and  37  and a double-convex positive lens of Surface No.  38  and  39 . And after the aperture stop AS of Surface No.  40 , there is the imaging optical system IL of Surface No.  41  through  49 . The imaging optical system IL is made up of a plane-parallel plate of Surface Nos.  41  and  42 , a positive meniscus lens convex on its object side, indicated by Surface Nos.  43  and  44 , a cemented lens of a double-convex positive lens and a double-concave negative lens, indicated by Surface Nos.  45 ,  46  and  47 , and a double-convex positive lens of Surface Nos.  48  and  49 . Following this, there is the optical member (plane-parallel plate) FT of Surface Nos.  50  and  51  positioned, after which there is the imaging plane (image plane) IP of Surface No.  54  positioned that has the CCD chip sealing glass DG of Surface Nos.  52  and  53 . 
     It should here be noted that a portion from the aperture stop AS to the imaging plane IP is decentered 4.2000 mm in the vertical direction to the optical axis of the objective lens optical system OB, afocal zoom optical system AZ and afocal relay optical system AL. 
     Aberration diagrams of this example similar to  FIGS. 13(   a ),  13 ( b ) and  13 ( c ) corresponding to  FIGS. 7(   a ),  7 ( b ) and  7 ( c ) are presented in  FIGS. 15(   a ),  15 ( b ) and  15 ( c ), respectively. 
       FIG. 8  is illustrative in lens arrangement section of the stereoscopic imaging optical system of Example 6 at (a) a low zoom ratio, (b) an intermediate zoom ratio and (c) a high zoom ratio (c) while at a working distance (WD) of 200 mm. For a left-and-right pair of components, only one is shown. 
     Example 6 is made up of the objective lens optical system OB common to both eyes, the subsequent afocal zoom optical system AZ and afocal relay optical system AL, and the subsequent left-and-right pair of aperture stops AS and imaging optical systems IL. The afocal zoom optical system AZ is made up of a positive first group G 1 , a negative second group G 2  and a positive third group G 3 , and the afocal relay optical system AL is made up of the positive front group GF and the positive rear group GR with the intermediate image IM held between them. Upon zooming from a low to a high zoom ratio, the first group G 1  in the afocal zoom optical system AZ first moves toward the object side and then goes back to the image plane side, and at the high zoom ratio it is positioned more on the image plane side than at the low zoom ratio. The second group G 2  moves toward the image plane side while the space between it and the first group G 1  grows wide, and the third group G 3  remains fixed. 
     The objective lens optical system OB is made up of a front group consisting of a cemented lens of a double-concave negative lens and a positive meniscus lens convex on its object side, and a rear group consisting of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, and a double-convex positive lens. By letting out that rear group toward the object side, the WD is kept long. 
     Referring now to the numerical data given later, Surface Nos.  1  and  2  are the end cover glass FG, Surface Nos.  3 ,  4  and  5  are the cemented lens in the front group in the objective lens optical system OB, Surface Nos.  9  and  10  are the double-convex positive lens in the rear group in the objective lens optical system OB, Surface No.  11  is the flare stop FS, and Surface Nos.  12  through  23  are the afocal zoom optical system AZ. The first group G 1  in the afocal zoom optical system AZ is made up of a cemented lens of a double-convex positive lens and a negative meniscus lens convex on its image plane side, indicated by Surface Nos.  12 ,  13  and  14 , the second group G 2  is made up of a cemented lens of a positive meniscus lens convex on its image plane side and a double-concave negative lens, indicated by Surface Nos.  15 ,  16  and  17  and a cemented lens of a plano-concave negative lens and a positive meniscus lens convex on its object side, indicated by Surface Nos.  18 ,  19  and  20 , and the third group G 3  is made up of a cemented lens of a negative meniscus lens convex on its object side and a double-convex positive lens, indicated by Surface Nos.  21 ,  22  and  23 . Following this, there is the flare stop FS of Surface No.  24  that is followed by the afocal relay optical system AL of Surface Nos.  25  through  39 . The front group GF in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  25  and  26 , a cemented lens of a double-convex positive lens and a double-concave negative lens, indicated by Surface Nos.  27 ,  28  and  29  and a positive meniscus lens convex on its object side, indicated by Surface Nos.  30  and  31 , and Surface No.  32  is the intermediate image IM. The rear group GR in the afocal relay optical system AL is made up of a double-convex positive lens of Surface Nos.  33  and  34 , a cemented lens of a double-concave negative lens and a double-convex positive lens, indicated by Surface Nos.  35 ,  36  and  37  and a double-convex positive lens of Surface Nos.  38  and  39 . After the aperture stop AS of Surface No.  40 , there is the imaging optical system IL of Surface Nos.  41  through  49 . The imaging optical system IL is made up of a plane-parallel plate of Surface Nos.  41  and  42 , a positive meniscus lens convex on its object side, indicated by Surface Nos.  43  and  44 , a cemented lens of a double-convex positive lens and a double-concave negative lens indicated by Surface Nos.  45 ,  46  and  47 , and a double-convex positive lens of Surface Nos.  48  and  49 . After this, there is the optical member (plane-parallel plate) FT of Surface Nos.  50  and  51  positioned, after which the imaging plane (image plane) IP of Surface No.  54  positioned that has the CCD chip sealing glass CG of Surface Nos.  52  and  53 . 
     It should here be noted that a portion from the aperture stop AS to the imaging plane IP is decentered 5.0000 mm in the vertical direction to the optical axis of the objective lens optical system OB, afocal zoom optical system AZ and afocal relay optical system AL. 
     Aberration diagrams of this example similar to  FIGS. 13(   a ),  13 ( b ) and  13 ( c ) corresponding to  FIGS. 8(   a ),  8 ( b ) and  8 ( c ) are presented in  FIGS. 16(   a ),  16 ( b ) and  16 ( c ), respectively. 
     Set out below are the numerical data on Examples 1 through 6. In the following, “LM”, “SM”, “HM”, “WD” and “MG” are indicative of a low zoom ratio end, an intermediate magnification, a high zoom ratio end, a working distance and a magnification, respectively, with “INF” indicative of infinity. 
     Example 1 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 4.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 7.0000 
               
               
                   
                  3 
                 −47.7464 
                 2.5000 
                 1.72000 
                 43.69 
               
               
                   
                  4 
                 48.1827 
                 6.5429 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 308.9917 
                 Variable 
               
               
                   
                  6 
                 172.9869 
                 3.0000 
                 1.84666 
                 23.78 
               
               
                   
                  7 
                 74.8421 
                 10.9301  
                 1.49700 
                 81.54 
               
               
                   
                  8 
                 −55.6530 
                 0.2000 
               
               
                   
                  9 
                 315.9099 
                 5.6845 
                 1.51742 
                 52.43 
               
               
                   
                 10 
                 −145.5527 
                 Variable 
               
               
                   
                 11 
                 66.0435 
                 2.5000 
                 1.48749 
                 70.23 
               
               
                   
                 12 
                 −125.8197 
                 0.2000 
               
               
                   
                 13 
                 37.1012 
                 3.0000 
                 1.48749 
                 70.23 
               
               
                   
                 14 
                 −354.0446 
                 1.5000 
                 1.80100 
                 34.97 
               
               
                   
                 15 
                 71.3269 
                 Variable 
               
               
                   
                 16 
                 −46.8052 
                 1.5000 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 −128.2160 
                 1.1726 
               
               
                   
                 18 
                 −70.1821 
                 1.2000 
                 1.51633 
                 64.14 
               
               
                   
                 19 
                 10.1313 
                 1.9281 
                 1.84666 
                 23.78 
               
               
                   
                 20 
                 13.4863 
                 Variable 
               
               
                   
                 21(Stop) 
                 INF 
                 2.8376 
               
               
                   
                 22 
                 17.4515 
                 2.0000 
                 1.62004 
                 36.26 
               
               
                   
                 23 
                 −52.4479 
                 0.2000 
               
               
                   
                 24 
                 159.5462 
                 1.2000 
                 1.80100 
                 34.97 
               
               
                   
                 25 
                 9.1524 
                 2.0000 
                 1.48749 
                 70.23 
               
               
                   
                 26 
                 −47.5162 
                 Variable 
               
               
                   
                 27 
                 −17.4646 
                 1.2000 
                 1.64769 
                 33.79 
               
               
                   
                 28 
                 33.2918 
                 2.5000 
                 1.88300 
                 40.76 
               
               
                   
                 29 
                 −19.2472 
                 Variable 
               
               
                   
                 30 
                 INF 
                 4.4436 
                 1.54771 
                 62.84 
               
               
                   
                 31 
                 INF 
                 1.9010 
               
               
                   
                 32 
                 INF 
                 1.9010 
                 1.51633 
                 64.14 
               
               
                   
                 33 
                 INF 
                 0.0001 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 −0.055 
                 −0.086 
                 −0.032 
                 −0.134 
                 −0.210 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 7.46760 
                 16.31128 
                 0.94639 
                 7.46760 
                 16.31128 
               
               
                 d10 
                 11.00000 
                 2.15632 
                 17.52121 
                 11.00000 
                 2.15632 
               
               
                 d15 
                 2.00187 
                 2.00187 
                 2.00187 
                 24.39575 
                 24.39575 
               
               
                 d20 
                 42.83668 
                 42.83668 
                 42.83668 
                 20.44279 
                 20.44279 
               
               
                 d26 
                 11.97120 
                 11.97120 
                 11.97120 
                 7.57992 
                 7.57992 
               
               
                 d29 
                 20.26873 
                 20.26873 
                 20.26873 
                 24.66000 
                 24.66000 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 −0.077 
                 −0.327 
                 −0.514 
                 −0.189 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 0.94639 
                 7.46760 
                 16.31128 
                 0.94639 
               
               
                   
                 d10 
                 17.52121 
                 11.00000 
                 2.15632 
                 17.52121 
               
               
                   
                 d15 
                 24.39575 
                 41.05094 
                 41.05094 
                 41.05094 
               
               
                   
                 d20 
                 20.44279 
                 3.78764 
                 3.78764 
                 3.78764 
               
               
                   
                 d26 
                 7.57992 
                 19.61868 
                 19.61868 
                 19.61868 
               
               
                   
                 d29 
                 24.66000 
                 12.62123 
                 12.62123 
                 12.62123 
               
               
                   
                   
               
             
          
         
       
     
     Example 2 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 5.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 8.0000 
               
               
                   
                  3 
                 −38.1697 
                 3.8657 
                 1.54072 
                 47.23 
               
               
                   
                  4 
                 45.3481 
                 8.0000 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 106.5783 
                 Variable 
               
               
                   
                  6 
                 339.2797 
                 7.0000 
                 1.62004 
                 36.26 
               
               
                   
                  7 
                 −86.2856 
                 0.2000 
               
               
                   
                  8 
                 93.2957 
                 4.0000 
                 1.84666 
                 23.78 
               
               
                   
                  9 
                 47.5470 
                 10.0000  
                 1.49700 
                 81.54 
               
               
                   
                 10 
                 −115.8492 
                 Variable 
               
               
                   
                 11 
                 61.5057 
                 2.8000 
                 1.48749 
                 70.23 
               
               
                   
                 12 
                 −174.8837 
                 0.2000 
               
               
                   
                 13 
                 34.5084 
                 3.2000 
                 1.48749 
                 70.23 
               
               
                   
                 14 
                 −3043.1666 
                 1.5000 
                 1.80100 
                 34.97 
               
               
                   
                 15 
                 60.8400 
                 Variable 
               
               
                   
                 16 
                 59.9528 
                 1.5000 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 49.6343 
                 2.0000 
               
               
                   
                 18 
                 −28.6883 
                 1.2000 
                 1.51633 
                 64.14 
               
               
                   
                 19 
                 11.0106 
                 1.8836 
                 1.84666 
                 23.78 
               
               
                   
                 20 
                 14.7361 
                 Variable 
               
               
                   
                 21(Stop) 
                 INF 
                 1.9833 
               
               
                   
                 22 
                 62.8650 
                 2.0000 
                 1.62004 
                 36.26 
               
               
                   
                 23 
                 −36.6853 
                 0.2000 
               
               
                   
                 24 
                 70.4137 
                 1.2000 
                 1.80100 
                 34.97 
               
               
                   
                 25 
                 12.4512 
                 2.0000 
                 1.48749 
                 70.23 
               
               
                   
                 26 
                 −26.3168 
                 Variable 
               
               
                   
                 27 
                 −12.3601 
                 1.2000 
                 1.64769 
                 33.79 
               
               
                   
                 28 
                 26.8585 
                 2.5000 
                 1.88300 
                 40.76 
               
               
                   
                 29 
                 −15.8201 
                 Variable 
               
               
                   
                 30 
                 INF 
                 4.4436 
                 1.54771 
                 62.84 
               
               
                   
                 31 
                 INE 
                 1.9010 
               
               
                   
                 32 
                 INF 
                 1.9010 
                 1.51633 
                 64.14 
               
               
                   
                 33 
                 INF 
                 0.0000 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 −0.055 
                 −0.087 
                 −0.032 
                 −0.135 
                 −0.212 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 9.11025 
                 17.42919 
                 2.93502 
                 9.11025 
                 17.42919 
               
               
                 d10 
                 10.00000 
                 1.68106 
                 16.17523 
                 10.00000 
                 1.68106 
               
               
                 d15 
                 1.98945 
                 1.98945 
                 1.98945 
                 24.84908 
                 24.84908 
               
               
                 d20 
                 43.74026 
                 43.74026 
                 43.74026 
                 20.88063 
                 20.88063 
               
               
                 d26 
                 12.12887 
                 12.12887 
                 12.12887 
                 7.65301 
                 7.65301 
               
               
                 d29 
                 20.50251 
                 20.50251 
                 20.50251 
                 24.97840 
                 24.97840 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 −0.079 
                 −0.332 
                 −0.519 
                 −0.193 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 2.93502 
                 9.11025 
                 17.42919 
                 2.93502 
               
               
                   
                 d10 
                 16.17523 
                 10.00000 
                 1.68106 
                 16.17523 
               
               
                   
                 d15 
                 24.84908 
                 41.47434 
                 41.47434 
                 41.47434 
               
               
                   
                 d20 
                 20.88063 
                 4.25541 
                 4.25541 
                 4.25541 
               
               
                   
                 d26 
                 7.65301 
                 19.95077 
                 19.95077 
                 19.95077 
               
               
                   
                 d29 
                 24.97840 
                 12.68060 
                 12.68060 
                 12.68060 
               
               
                   
                   
               
             
          
         
       
     
     Example 3 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 2.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 4.0000 
               
               
                   
                  3 
                 −38.9866 
                 2.3000 
                 1.72000 
                 43.69 
               
               
                   
                  4 
                 30.2094 
                 5.0000 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 141.4871 
                 Variable 
               
               
                   
                  6 
                 844.4155 
                 2.4000 
                 1.76182 
                 26.52 
               
               
                   
                  7 
                 42.8249 
                 5.0000 
                 1.49700 
                 81.54 
               
               
                   
                  8 
                 −207.2773 
                 0.2000 
               
               
                   
                  9 
                 143.0459 
                 5.0000 
                 1.78800 
                 47.37 
               
               
                   
                 10 
                 −53.0139 
                 Variable 
               
               
                   
                 11 
                 301.6916 
                 2.0000 
                 1.69680 
                 55.53 
               
               
                   
                 12 
                 −79.7609 
                 0.2000 
               
               
                   
                 13 
                 25.2283 
                 2.2000 
                 1.69680 
                 55.53 
               
               
                   
                 14 
                 806.7235 
                 1.5000 
                 1.84666 
                 23.78 
               
               
                   
                 15 
                 46.6578 
                 Variable 
               
               
                   
                 16 
                 18.5970 
                 1.1777 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 11.6121 
                 1.1873 
               
               
                   
                 18 
                 −12.3112 
                 1.0000 
                 1.51633 
                 64.14 
               
               
                   
                 19 
                 8.2966 
                 1.6168 
                 1.84666 
                 23.78 
               
               
                   
                 20 
                 14.6164 
                 Variable 
               
               
                   
                 21(Stop) 
                 INF 
                 2.1998 
               
               
                   
                 22 
                 −11.3858 
                 2.9089 
                 1.51742 
                 52.43 
               
               
                   
                 23 
                 −11.2501 
                 0.2000 
               
               
                   
                 24 
                 18.8215 
                 3.5185 
                 1.48749 
                 70.23 
               
               
                   
                 25 
                 −7.3570 
                 1.0000 
                 1.80100 
                 34.97 
               
               
                   
                 26 
                 −13.2065 
                 Variable 
               
               
                   
                 27 
                 −99.2269 
                 1.0000 
                 1.72825 
                 28.46 
               
               
                   
                 28 
                 46.8422 
                 2.6666 
                 1.69350 
                 53.20 
               
               
                   
                 29 
                 −24.0466 
                 Variable 
               
               
                   
                 30 
                 INF 
                 2.4173 
                 1.54771 
                 62.84 
               
               
                   
                 31 
                 INF 
                 1.0342 
               
               
                   
                 32 
                 INF 
                 1.0342 
                 1.51633 
                 64.14 
               
               
                   
                 33 
                 INF 
                 0.0000 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 −0.030 
                 −0.050 
                 −0.017 
                 −0.074 
                 −0.122 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 5.73770 
                 11.75525 
                 1.64246 
                 5.73770 
                 11.75525 
               
               
                 d10 
                 8.00000 
                 1.98245 
                 12.09524 
                 8.00000 
                 1.98245 
               
               
                 d15 
                 2.01300 
                 2.01300 
                 2.01300 
                 15.00261 
                 15.00261 
               
               
                 d20 
                 26.82074 
                 26.82074 
                 26.82074 
                 13.83112 
                 13.83112 
               
               
                 d26 
                 7.81433 
                 7.81433 
                 7.81433 
                 5.24581 
                 5.24581 
               
               
                 d29 
                 11.96285 
                 11.96285 
                 11.96285 
                 14.53136 
                 14.53136 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 −0.041 
                 −0.181 
                 −0.298 
                 −0.101 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 1.64246 
                 5.73770 
                 11.75525 
                 1.64246 
               
               
                   
                 d10 
                 12.09524 
                 8.00000 
                 1.98245 
                 12.09524 
               
               
                   
                 d15 
                 15.00261 
                 23.77576 
                 23.77576 
                 23.77576 
               
               
                   
                 d20 
                 13.83112 
                 5.05798 
                 5.05798 
                 5.05798 
               
               
                   
                 d26 
                 5.24581 
                 12.50829 
                 12.50829 
                 12.50829 
               
               
                   
                 d29 
                 14.53136 
                 7.26888 
                 7.26888 
                 7.26888 
               
               
                   
                   
               
             
          
         
       
     
     Example 4 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 2.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 7.0000 
               
               
                   
                  3 
                 −44.6801 
                 2.3000 
                 1.72000 
                 43.69 
               
               
                   
                  4 
                 48.3881 
                 7.1082 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 318.5902 
                 Variable 
               
               
                   
                  6 
                 169.9400 
                 2.5000 
                 1.84666 
                 23.78 
               
               
                   
                  7 
                 73.2558 
                 9.2642 
                 1.49700 
                 81.54 
               
               
                   
                  8 
                 −62.6930 
                 0.2000 
               
               
                   
                  9 
                 725.0873 
                 8.2212 
                 1.51742 
                 52.43 
               
               
                   
                 10 
                 −85.1320 
                 Variable 
               
               
                   
                 11 
                 INF 
                 Variable 
               
               
                   
                 12 
                 91.2516 
                 9.2286 
                 1.48749 
                 70.21 
               
               
                   
                 13 
                 −61.8721 
                 4.3429 
                 1.85026 
                 32.29 
               
               
                   
                 14 
                 −104.6601 
                 Variable 
               
               
                   
                 15 
                 −134.4576 
                 4.3429 
                 1.69895 
                 30.12 
               
               
                   
                 16 
                 −33.1197 
                 2.7143 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 54.0143 
                 3.9086 
               
               
                   
                 18 
                 INF 
                 2.7143 
                 1.60311 
                 60.70 
               
               
                   
                 19 
                 27.3627 
                 5.9714 
                 1.83400 
                 37.17 
               
               
                   
                 20 
                 73.1826 
                 Variable 
               
               
                   
                 21 
                 151.1097 
                 4.0714 
                 1.74000 
                 31.71 
               
               
                   
                 22 
                 76.1764 
                 7.3286 
                 1.48749 
                 70.21 
               
               
                   
                 23 
                 −105.6481 
                 1.5079 
               
               
                   
                 24 
                 INF 
                 2.4576 
               
               
                   
                 25 
                 122.1364 
                 7.7156 
                 1.72916 
                 54.68 
               
               
                   
                 26 
                 −8389.0707 
                 1.4570 
               
               
                   
                 27 
                 40.0790 
                 28.5137 
                 1.49700 
                 81.54 
               
               
                   
                 28 
                 −342.3266 
                 4.7763 
                 1.80100 
                 34.97 
               
               
                   
                 29 
                 32.3499 
                 28.5252 
               
               
                   
                 30 
                 75.4974 
                 8.0869 
                 1.78800 
                 47.37 
               
               
                   
                 31 
                 157700.0000 
                 53.9326 
               
               
                   
                 32 
                 INF 
                 23.7196 
               
               
                   
                 33 
                 78.3905 
                 6.4649 
                 1.72916 
                 54.68 
               
               
                   
                 34 
                 −54.0423 
                 25.5253 
               
               
                   
                 35 
                 −19.9811 
                 4.1242 
                 1.80100 
                 34.97 
               
               
                   
                 36 
                 100.1661 
                 19.1718 
                 1.49700 
                 81.54 
               
               
                   
                 37 
                 −26.2721 
                 1.0032 
               
               
                   
                 38 
                 254.8381 
                 10.2547 
                 1.72916 
                 54.68 
               
               
                   
                 39 
                 −93.3311 
                 14.1071 
               
               
                   
                 40(Stop) 
                 INF 
                 1.1905 
               
               
                   
                 41 
                 INF 
                 19.0476 
                 1.80610 
                 40.92 
               
               
                   
                 42 
                 INF 
                 3.4524 
               
               
                   
                 43 
                 17.9187 
                 5.1372 
                 1.77250 
                 49.60 
               
               
                   
                 44 
                 99.2240 
                 1.2383 
               
               
                   
                 45 
                 13.9102 
                 4.2921 
                 1.49700 
                 81.54 
               
               
                   
                 46 
                 −32.3689 
                 1.1636 
                 1.80100 
                 34.97 
               
               
                   
                 47 
                 10.0010 
                 9.8698 
               
               
                   
                 48 
                 33.7316 
                 2.4441 
                 1.72916 
                 54.68 
               
               
                   
                 49 
                 −33.7316 
                 11.4922 
               
               
                   
                 50 
                 INF 
                 2.9762 
                 1.51633 
                 64.14 
               
               
                   
                 51 
                 INF 
                 0.0060 
               
               
                   
                 52 
                 INF 
                 1.1905 
                 1.61350 
                 50.20 
               
               
                   
                 53 
                 INF 
                 0.0017 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 0.067 
                 0.106 
                 0.038 
                 0.161 
                 0.256 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 7.40545 
                 15.60189 
                 1.47307 
                 7.40545 
                 15.60189 
               
               
                 d10 
                 9.00000 
                 0.80356 
                 14.93238 
                 9.00000 
                 0.80356 
               
               
                 d11 
                 22.81629 
                 22.81629 
                 22.81629 
                 1.06671 
                 1.06671 
               
               
                 d14 
                 3.68326 
                 3.68326 
                 3.68326 
                 51.18641 
                 51.18641 
               
               
                 d20 
                 94.44926 
                 94.44926 
                 94.44926 
                 68.69660 
                 68.69660 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 0.093 
                 0.402 
                 0.638 
                 0.231 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 1.47307 
                 7.40545 
                 15.60189 
                 1.47307 
               
               
                   
                 d10 
                 14.93238 
                 9.00000 
                 0.80356 
                 14.93238 
               
               
                   
                 d11 
                 1.06671 
                 46.49843 
                 46.49843 
                 46.49843 
               
               
                   
                 d14 
                 51.18641 
                 71.35429 
                 71.35429 
                 71.35429 
               
               
                   
                 d20 
                 68.69660 
                 3.09545 
                 3.09545 
                 3.09545 
               
               
                   
                   
               
             
          
         
       
     
     Example 5 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 2.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 7.0000 
               
               
                   
                  3 
                 −44.6801 
                 2.3000 
                 1.72000 
                 43.69 
               
               
                   
                  4 
                 48.3881 
                 7.1082 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 318.5902 
                 Variable 
               
               
                   
                  6 
                 169.9400 
                 2.5000 
                 1.84666 
                 23.78 
               
               
                   
                  7 
                 73.2558 
                 9.2642 
                 1.49700 
                 81.54 
               
               
                   
                  8 
                 −62.6930 
                 0.2000 
               
               
                   
                  9 
                 725.0873 
                 8.2212 
                 1.51742 
                 52.43 
               
               
                   
                 10 
                 −85.1320 
                 Variable 
               
               
                   
                 11 
                 INF 
                 Variable 
               
               
                   
                 12 
                 91.2516 
                 9.2286 
                 1.48749 
                 70.21 
               
               
                   
                 13 
                 −61.8721 
                 4.3429 
                 1.85026 
                 32.29 
               
               
                   
                 14 
                 −104.6601 
                 Variable 
               
               
                   
                 15 
                 −134.4576 
                 4.3429 
                 1.69895 
                 30.12 
               
               
                   
                 16 
                 −33.1197 
                 2.7143 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 54.0143 
                 3.9086 
               
               
                   
                 18 
                 INF 
                 2.7143 
                 1.60311 
                 60.70 
               
               
                   
                 19 
                 27.3627 
                 5.9714 
                 1.83400 
                 37.17 
               
               
                   
                 20 
                 73.1826 
                 Variable 
               
               
                   
                 21 
                 151.1097 
                 4.0714 
                 1.74000 
                 31.71 
               
               
                   
                 22 
                 76.1764 
                 7.3286 
                 1.48749 
                 70.21 
               
               
                   
                 23 
                 −105.6481 
                 1.5079 
               
               
                   
                 24 
                 INF 
                 2.7033 
               
               
                   
                 25 
                 134.3501 
                 8.4871 
                 1.72916 
                 54.68 
               
               
                   
                 26 
                 −9227.9778 
                 1.6027 
               
               
                   
                 27 
                 44.0869 
                 31.3650 
                 1.49700 
                 81.54 
               
               
                   
                 28 
                 −376.5592 
                 5.2540 
                 1.80100 
                 34.97 
               
               
                   
                 29 
                 35.5849 
                 31.3777 
               
               
                   
                 30 
                 83.0471 
                 8.8956 
                 1.78800 
                 47.37 
               
               
                   
                 31 
                 173400.0000 
                 59.3259 
               
               
                   
                 32 
                 INF 
                 33.2074 
               
               
                   
                 33 
                 109.7467 
                 9.0509 
                 1.72916 
                 54.68 
               
               
                   
                 34 
                 −75.6592 
                 35.7354 
               
               
                   
                 35 
                 −27.9735 
                 5.7738 
                 1.80100 
                 34.97 
               
               
                   
                 36 
                 140.2325 
                 26.8406 
                 1.49700 
                 81.54 
               
               
                   
                 37 
                 −36.7809 
                 1.4044 
               
               
                   
                 38 
                 356.7734 
                 14.3566 
                 1.72916 
                 54.68 
               
               
                   
                 39 
                 −130.6636 
                 19.7500 
               
               
                   
                 40(Stop) 
                 INF 
                 1.5152 
               
               
                   
                 41 
                 INF 
                 24.2424 
                 1.80610 
                 40.92 
               
               
                   
                 42 
                 INF 
                 4.3939 
               
               
                   
                 43 
                 22.8057 
                 6.5382 
                 1.77250 
                 49.60 
               
               
                   
                 44 
                 126.2851 
                 1.5761 
               
               
                   
                 45 
                 17.7040 
                 5.4627 
                 1.49700 
                 81.54 
               
               
                   
                 46 
                 −41.1967 
                 1.4810 
                 1.80100 
                 34.97 
               
               
                   
                 47 
                 12.7286 
                 12.5616 
               
               
                   
                 48 
                 42.9312 
                 3.1107 
                 1.72916 
                 54.68 
               
               
                   
                 49 
                 −42.9312 
                 14.6265 
               
               
                   
                 50 
                 INF 
                 3.7879 
                 1.51633 
                 64.14 
               
               
                   
                 51 
                 INF 
                 0.0076 
               
               
                   
                 52 
                 INF 
                 1.5152 
                 1.61350 
                 50.20 
               
               
                   
                 53 
                 INF 
                 0.0023 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 0.067 
                 0.106 
                 0.038 
                 0.161 
                 0.256 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 7.40545 
                 15.60189 
                 1.47307 
                 7.40545 
                 15.60189 
               
               
                 d10 
                 9.00000 
                 0.80356 
                 14.93238 
                 9.00000 
                 0.80356 
               
               
                 d11 
                 22.81629 
                 22.81629 
                 22.81629 
                 1.06671 
                 1.06671 
               
               
                 d14 
                 3.68326 
                 3.68326 
                 3.68326 
                 51.18641 
                 51.18641 
               
               
                 d20 
                 94.44926 
                 94.44926 
                 94.44926 
                 68.69660 
                 68.69660 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 0.093 
                 0.402 
                 0.638 
                 0.231 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 1.47307 
                 7.40545 
                 15.60189 
                 1.47307 
               
               
                   
                 d10 
                 14.93238 
                 9.00000 
                 0.80356 
                 14.93238 
               
               
                   
                 d11 
                 1.06671 
                 46.49843 
                 46.49843 
                 46.49843 
               
               
                   
                 d14 
                 51.18641 
                 71.35429 
                 71.35429 
                 71.35429 
               
               
                   
                 d20 
                 68.69660 
                 3.09545 
                 3.09545 
                 3.09545 
               
               
                   
                   
               
             
          
         
       
     
     Example 6 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 No 
                 r 
                 d 
                 nd 
                 vd 
               
               
                   
                   
               
               
                   
                 Object plane 
                 INF 
                 Variable 
               
               
                   
                  1 
                 INF 
                 2.0000 
                 1.76820 
                 71.79 
               
               
                   
                  2 
                 INF 
                 7.0000 
               
               
                   
                  3 
                 −44.6801 
                 2.3000 
                 1.72000 
                 43.69 
               
               
                   
                  4 
                 48.3881 
                 7.1082 
                 1.84666 
                 23.78 
               
               
                   
                  5 
                 318.5902 
                 Variable 
               
               
                   
                  6 
                 169.9400 
                 2.5000 
                 1.84666 
                 23.78 
               
               
                   
                  7 
                 73.2558 
                 9.2642 
                 1.49700 
                 81.54 
               
               
                   
                  8 
                 −62.6930 
                 0.2000 
               
               
                   
                  9 
                 725.0873 
                 8.2212 
                 1.51742 
                 52.43 
               
               
                   
                 10 
                 −85.1320 
                 Variable 
               
               
                   
                 11 
                 INF 
                 Variable 
               
               
                   
                 12 
                 91.2516 
                 9.2286 
                 1.48749 
                 70.21 
               
               
                   
                 13 
                 −61.8721 
                 4.3429 
                 1.85026 
                 32.29 
               
               
                   
                 14 
                 −104.6601 
                 Variable 
               
               
                   
                 15 
                 −134.4576 
                 4.3429 
                 1.69895 
                 30.12 
               
               
                   
                 16 
                 −33.1197 
                 2.7143 
                 1.77250 
                 49.60 
               
               
                   
                 17 
                 54.0143 
                 3.9086 
               
               
                   
                 18 
                 INF 
                 2.7143 
                 1.60311 
                 60.70 
               
               
                   
                 19 
                 27.3627 
                 5.9714 
                 1.83400 
                 37.17 
               
               
                   
                 20 
                 73.1826 
                 Variable 
               
               
                   
                 21 
                 151.1097 
                 4.0714 
                 1.74000 
                 31.71 
               
               
                   
                 22 
                 76.1764 
                 7.3286 
                 1.48749 
                 70.21 
               
               
                   
                 23 
                 −105.6481 
                 1.5079 
               
               
                   
                 24 
                 INF 
                 2.8262 
               
               
                   
                 25 
                 140.4569 
                 8.8729 
                 1.72916 
                 54.68 
               
               
                   
                 26 
                 −9647.4313 
                 1.6755 
               
               
                   
                 27 
                 46.0908 
                 32.7907 
                 1.49700 
                 81.54 
               
               
                   
                 28 
                 −393.6755 
                 5.4928 
                 1.80100 
                 34.97 
               
               
                   
                 29 
                 37.2024 
                 32.8039 
               
               
                   
                 30 
                 86.8220 
                 9.3000 
                 1.78800 
                 47.37 
               
               
                   
                 31 
                 181300.0000 
                 62.0225 
               
               
                   
                 32 
                 INF 
                 39.8489 
               
               
                   
                 33 
                 131.6960 
                 10.8611 
                 1.72916 
                 54.68 
               
               
                   
                 34 
                 −90.7910 
                 42.8825 
               
               
                   
                 35 
                 −33.5682 
                 6.9286 
                 1.80100 
                 34.97 
               
               
                   
                 36 
                 168.2790 
                 32.2087 
                 1.49700 
                 81.54 
               
               
                   
                 37 
                 −44.1371 
                 1.6853 
               
               
                   
                 38 
                 428.1281 
                 17.2279 
                 1.72916 
                 54.68 
               
               
                   
                 39 
                 −156.7963 
                 23.7000 
               
               
                   
                 40(Stop) 
                 INF 
                 0.8696 
               
               
                   
                 41 
                 INF 
                 13.9130 
                 1.80610 
                 40.92 
               
               
                   
                 42 
                 INF 
                 2.5217 
               
               
                   
                 43 
                 13.0885 
                 3.7524 
                 1.77250 
                 49.60 
               
               
                   
                 44 
                 72.4767 
                 0.9045 
               
               
                   
                 45 
                 10.1605 
                 3.1351 
                 1.49700 
                 81.54 
               
               
                   
                 46 
                 −23.6433 
                 0.8499 
                 1.80100 
                 34.97 
               
               
                   
                 47 
                 7.3051 
                 7.2092 
               
               
                   
                 48 
                 24.6388 
                 1.7853 
                 1.72916 
                 54.68 
               
               
                   
                 49 
                 −24.6388 
                 8.3943 
               
               
                   
                 50 
                 INF 
                 2.1739 
                 1.51633 
                 64.14 
               
               
                   
                 51 
                 INF 
                 0.0043 
               
               
                   
                 52 
                 INF 
                 0.8696 
                 1.61350 
                 50.20 
               
               
                   
                 53 
                 INF 
                 0.0014 
               
               
                   
                 Image plane 
                 INF 
               
               
                   
                   
               
             
          
           
               
                 Variable spaces 
               
               
                   
               
             
          
           
               
                 No 
                 LM 
                 LM 
                 LM 
                 SM 
                 SM 
               
               
                   
               
               
                 MG 
                 0.033 
                 0.053 
                 0.019 
                 0.081 
                 0.128 
               
               
                 d0 WD 
                 200.00000 
                 100.00000 
                 400.00000 
                 200.00000 
                 100.00000 
               
               
                 d5 
                 7.40545 
                 15.60189 
                 1.47307 
                 7.40545 
                 15.60189 
               
               
                 d10 
                 9.00000 
                 0.80356 
                 14.93238 
                 9.00000 
                 0.80356 
               
               
                 d11 
                 22.81629 
                 22.81629 
                 22.81629 
                 1.06671 
                 1.06671 
               
               
                 d14 
                 3.68326 
                 3.68326 
                 3.68326 
                 51.18641 
                 51.18641 
               
               
                 d20 
                 94.44926 
                 94.44926 
                 94.44926 
                 68.69660 
                 68.69660 
               
               
                   
               
             
          
           
               
                   
                 No 
                 SM 
                 HM 
                 HM 
                 HM 
               
               
                   
                   
               
               
                   
                 MG 
                 0.046 
                 0.201 
                 0.319 
                 0.115 
               
               
                   
                 d0 WD 
                 400.00000 
                 200.00000 
                 100.00000 
                 400.00000 
               
               
                   
                 d5 
                 1.47307 
                 7.40545 
                 15.60189 
                 1.47307 
               
               
                   
                 d10 
                 14.93238 
                 9.00000 
                 0.80356 
                 14.93238 
               
               
                   
                 d11 
                 1.06671 
                 46.49843 
                 46.49843 
                 46.49843 
               
               
                   
                 d14 
                 51.18641 
                 71.35429 
                 71.35429 
                 71.35429 
               
               
                   
                 d20 
                 68.69660 
                 3.09545 
                 3.09545 
                 3.09545 
               
               
                   
                   
               
             
          
         
       
     
     Tabulated below are the image-side effective F-numbers (Fno) of Examples 1 through 6 and the image height on the imaging device. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Example 
                 1 
                 2 
                 3 
               
               
                   
                   
               
             
          
           
               
                   
                 Image-Side 
                 Low zoom 
                 8.4 
                 8.6 
                 4.9 
               
               
                   
                 Effective 
                 ratio end 
               
               
                   
                 Fno 
                 Intermediate 
                 8.5 
                 8.6 
                 4.9 
               
               
                   
                   
                 High zoom 
                 8.7 
                 9.0 
                 5.1 
               
               
                   
                   
                 ratio end 
               
             
          
           
               
                   
                 Image Height on the 
                 3 
                 3 
                 1.632 
               
               
                   
                 Imaging Device 
               
               
                   
                   
               
             
          
           
               
                   
                 Example 
                 4 
                 5 
                 6 
               
               
                   
                   
               
             
          
           
               
                   
                 Image-Side 
                 Low zoom 
                 10.5 
                 10.5 
                 10.5 
               
               
                   
                 Effective 
                 ratio end 
               
               
                   
                 Fno 
                 Intermediate 
                 10.5 
                 10.5 
                 10.5 
               
               
                   
                   
                 High zoom 
                 10.5 
                 10.5 
                 10.5 
               
               
                   
                   
                 ratio end 
               
             
          
           
               
                   
                 Image Height on the 
                 3.264 
                 3.264 
                 1.632 
               
               
                   
                 Imaging Device 
               
               
                   
                   
               
             
          
         
       
     
     Tabulated below are also the values of the conditions and the values of the conditions&#39; elements in Examples 1 to 6. 
     
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Example 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
                   
               
             
          
           
               
                 Imaging 
                 ⅓ 
                 ⅓ 
                 ⅙ 
                 ⅓ 
                 ⅓ 
                 ⅙ 
               
               
                 device 
               
               
                 size in 
               
               
                 inch 
               
               
                 mgrw 
                 −0.456 
                 −0.437 
                 −0.417 
                 — 
                 — 
                 — 
               
               
                 ΔG4/ΔG2 
                 0.196 
                 0.198 
                 0.216 
                 — 
                 — 
                 — 
               
               
                 fF/LZ 
                 — 
                 — 
                 — 
                 0.736 
                 0.809 
                 0.486 
               
               
                 fF/fR 
                 — 
                 — 
                 — 
                 1.680 
                 1.320 
                 1.150 
               
               
                 fm/IH 
                 — 
                 — 
                 — 
                 12.160 
                 9.554 
                 13.958 
               
               
                 ΔG4 
                 7.648 
                 7.822 
                 4.694 
                 — 
                 — 
                 — 
               
               
                 ΔG2 
                 39.049 
                 39.485 
                 21.763 
                 — 
                 — 
                 — 
               
               
                 fF 
                 — 
                 — 
                 — 
                 121.000 
                 133.00 
                 139.150 
               
               
                 LZ 
                 — 
                 — 
                 — 
                 164.506 
                 164.506 
                 164.506 
               
               
                 fR 
                 — 
                 — 
                 — 
                 72.024 
                 100.833 
                 121.00 
               
               
                 fm 
                 — 
                 — 
                 — 
                 39.690 
                 31.185 
                 22.779 
               
               
                 IH 
                 — 
                 — 
                 — 
                 3.264 
                 3.264 
                 1.632