Microscope system

1. A microscope system comprising, at least:

an objective lens which converts a luminous flux emergent from an object into a parallel luminous flux,

an afocal variable magnification optical system which changes a diameter of the parallel luminous flux emergent from the objective lens into a different diameter, and

an image forming optical system for forming an image out of the parallel luminous flux emergent from the afocal variable magnification optical system,

wherein the following conditions are satisfied:

2· NA ( ob )· FL ( ob )≧30 (mm)

6≦ Lexz/X≦ 10

where NA(ob) is a maximum effective numerical aperture of an objective lens, FL(ob) is a focal length, in millimeters, of the objective lens, X=2·NA(ob)·FL(ob), Lexz is a distance, in millimeters, from an object surface to a most distant end of the afocal variable magnification optical system.

2. The microscope system according to claim 1 , wherein the microscope system is adapted to a mode in which illuminating light having a selected wavelength is projected on a sample and light emitted from the sample but having a wavelength different from the wavelength of the illuminating light is used for observation, upon further comprising a filter for separating the wavelength of the illuminating light and the wavelength of the light for observation, and

wherein the filter is arranged within a range satisfying the following condition:

L ( f )= F ( TL )/3

where L(f) is a distance, in millimeters, from an exit end of the afocal variable magnification optical system to the filter, and F(TL) is a focal length, in millimeters, of the image forming lens.

3. A microscope system comprising, at least:

an objective lens which converts a luminous flux emergent from an object into a parallel luminous flux,

an afocal variable magnification optical system which changes a diameter of the parallel luminous flux emergent from the objective lens into a different diameter, and

an image forming optical system for forming an image out of the parallel luminous flux emergent from the afocal variable magnification optical system,

wherein the afocal variable magnification optical system and the image forming optical system are arranged to keep an interval L satisfying the following condition:

L>F ( TL )/2 (mm)

where L is a distance, in millimeters, from an exit end of the afocal variable magnification optical system to an entrance end of the image forming lens, and F(TL) is a focal length, in millimeters, of the image forming lens, and

wherein the following condition is also satisfied:

D ( TL )≧EXP(max)*1.25 (mm)

where D(TL) is an effective diameter, in millimeters, of the image forming lens, and EXP(max) is a diameter, in millimeters, of a largest exit pupil of the afocal variable magnification optical system.

4. The microscope system according to claim 3 , wherein:

the microscope system is adapted to a mode in which illuminating light having a selected wavelength is projected on a sample and light emitted from the sample but having a wavelength different from the wavelength of the illuminating light is used for observation, upon further comprising a filter for separating the wavelength of the illuminating light and the wavelength of the light for observation, and

the filter is arranged within a range satisfying the following condition:

L ( f )= F ( TL )/3

where L(f) is a distance, in millimeters, from an exit end of the afocal variable magnification optical system to the filter, and F(TL) is a focal length, in millimeters, of the image forming lens.

5. A microscope system comprising, at least:

a plurality of objective lenses each for converting a luminous flux emergent from an object into a parallel luminous flux,

an afocal variable magnification optical system which changes a diameter of the parallel luminous flux emergent from each of the objective lenses into a different diameter, and

an image forming optical system for forming an image out of the parallel luminous flux emergent from the afocal variable magnification optical system,

wherein the plurality of objective lenses satisfy the following conditions:

2· NA ( ob )· FL ( ob )≧30 (mm)

X (Max)/ X (Min)<1.25

M ( obH )/ M ( obL )≧2

L ( ob Max)/ L ( ob Min)<1.1

where NA(ob) is a maximum effective numerical aperture of each of the objective lenses, FL(ob) is a focal length, in millimeters, of each of the objective lenses, X(Max) is a maximum value of 2·NA(ob)·FL(ob), X(Min) is a minimum value of 2·NA(ob)·FL(ob), M(obH) is a magnification of an objective lens with a highest magnification among the plurality of objective lenses, M(obL) is a magnification of an objective lens with a lowest magnification among the plurality of objective lenses, L(ob Max) is a maximum value of distances, in millimeters, from an object surface to utmost surfaces of the objective lenses, and L(ob Min) is a minimum value of the distances, in millimeters, from the object surface to the utmost surfaces of the objective lenses.

6. The microscope system according to claim 5 , wherein:

the microscope system is adapted to a mode in which illuminating light having a selected wavelength is projected on a sample and light emitted from the sample but having a wavelength different from the wavelength of the illuminating light is used for observation, upon further comprising a filter for separating the wavelength of the illuminating light and the wavelength of the light for observation, and

the filter is arranged within a range satisfying the following condition:

L ( f )= F ( TL )/3

where L(f) is a distance, in millimeters, from an exit end of the afocal variable magnification optical system to the filter, and F( TL ) is a focal length, in millimeters, of the image forming lens.

7. A microscope system comprising, at least:

an objective lens which converts a luminous flux emergent from an object into a parallel luminous flux,

a first afocal variable magnification optical system which changes a diameter of the parallel luminous flux emergent from the objective lens into a different diameter,

an image forming optical system for forming an image out of the parallel luminous flux emergent from the first afocal variable magnification optical system, and

a second afocal variable magnification optical system configured to be insertable between the objective lens and the first afocal variable magnification optical system,

wherein the following conditions are satisfied:

M ( ca )≧0.8

ENP (max)≧EXP( ob )/ M ( ca )

where M(ca) is a magnification of the second afocal variable magnification optical system, ENP(max) is a diameter, in millimeters, of a largest exit pupil of the first afocal variable magnification optical system, and EXP(ob) is a diameter, in millimeters, of an exit pupil of the objective lens.

8. The microscope system according to claim 7 , wherein:

the microscope system is adapted to a mode in which illuminating light having a selected wavelength is projected on a sample and light emitted from the sample but having a wavelength different from the wavelength of the illuminating light is used for observation, upon further comprising a filter for separating the wavelength of the illuminating light and the wavelength of the light for observation, and

the filter is arranged within a range satisfying the following condition:

L ( f )= F ( TL )/3

where L(f) is a distance, in millimeters, from an exit end of the first afocal variable magnification optical system to the filter, and F(TL) is a focal length, in millimeters, of the image forming lens.