Optical system for microscopes

Abstract

An optical system for microscopes includes an objective lens for collimating beams of light emanating from an object and an imaging lens for forming parallel beams emerging from the objective lens into an image of the object at a predetermined position, and satisfies the equation: 0.5 f<W<1.1 f where W is the variable amount of spacing from the contact surface of the objective lens to the surface of incidence of the imaging lens and f is the focal length of the imaging lens. Thus, the optical system for microscopes allows a large variable amount to be secured while holding a good imaging condition and is unsurpassed in extensity of the system to be able to accommodate various modes of observation.

What is claimed is: 
     
       1. An optical system for microscopes comprising: an objective lens for converting light from an object into substantially parallel beams; and   an imaging lens for focusing the beams from said objective lens to form a magnified image of the object at a predetermined position,   wherein a distance from a contact surface of said objective lens to a surface closest to said objective lens, of said imaging lens, is variable and said optical system satisfies the condition:   0.5f<W<1.1f     where W is the amount of change of the distance from the contact surface of the objective lens to the surface closest to the objective lens, of the imaging lens, and f is the focal length of the imaging lens;     wherein said optical system for microscopes is adapted to allow insertion and removal of lens elements between said lenses.   
     
     
       2. An optical system for microscopes comprising: an objective lens for converting light from an object into substantially parallel beams; and   an imaging lens equipped with a first lens component having a positive refractive power and a second lens component including a negative cemented doublet configured by cementing a positive lens to a negative lens, said imaging lens for focusing the beams from said objective lens to form a magnified image of the object at a predetermined position,   wherein a distance from a contact surface of said objective lens to a surface closest to said objective lens, of said imaging lens, is variable and said optical system satisfies conditions:   0.5f≦W<1.1f       0.75f<f.sub.1 <0.9f       0.77<|fO.sub.2 /fT.sub.2 |<1.0       0.14f<ED.sub.1 <0.19f     where W is the amount of change of the distance from the contact surface of the objective lens to the surface closest to the objective lens, of the imaging lens, f is the focal length of the imaging lens, f 1  is the focal length of the first lens component, fT 2  is the focal length of the positive lens of the second lens component, fO 2  is the focal length of the negative lens of the second lens component, and ED 1  is the effective diameter of the first lens component. .Iadd.     
     
     
       3.  An optical system for microscopes comprising: an objective lens for converting light from an object into substantially parallel beams; and   an imaging lens for focusing the beams from said objective lens to form a magnified image of the object at a predetermined position, wherein a distance from a contact surface of said objective lens to a surface closest to said objective lens, of said imaging lens, is variable and said optical system satisfies the condition:   0.5 f<W<1.1 f       where W is the amount of change of the distance form the contact surface to the objective lens to the surface closest to the objective lens, of the imaging lens, and f is the focal length of the imaging lens; wherein said optical system for microscopes is adapted to allow insertion and removal of intermediate lens barrels between said lenses. .Iaddend..Iadd.4. An optical system for microscopes according to claim 3, wherein said optical system for microscopes is adapted to allow insertion and removal of two to three intermediate lens barrels at the same time between said lenses. .Iaddend..Iadd.5. An optical system for microscopes according to claim 3 or 4, wherein said intermediate lens barrels comprise an intermediate magnification lens barrel. .Iaddend..Iadd.6. An optical system for microscopes according to claim 3 or 4, wherein said intermediate lens barrels comprise a reflecting projection tube. .Iaddend..Iadd.7. An optical system for microscopes according to claim 3 or 4, wherein said intermediate lens barrels comprise a discussion lens barrel. .Iaddend.