Microscope objective lens including a diffractive optical element

摘要

A microscope objective lens OL includes, in order from the object side: a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power, wherein the first lens group G1 includes a positive lens component L1 having a lens surface with a negative refractive power and at least one cemented lens component CL11 having a positive refractive power, the second lens group G2 includes a diffractive optical element GD that joins two diffractive element components L6 and L7 respectively made from different optical materials and which has a diffractive optical surface D on which diffractive grating grooves are formed on the bonded surface of the two diffractive element components, and at least one cemented lens component CL21, and the third lens group G3 includes at least one achromatic lens component CL31.

主权项

1. A microscope objective lens comprising, in order from an object side:
a first lens group having a positive refractive power, a second lens group, and a third lens group having a negative refractive power, wherein the first lens group includes a positive lens component having a lens surface positioned nearest to the object side and having a negative refractive power and at least one cemented lens component having a combined positive refractive power, the second lens group includes a diffractive optical element that joins two diffractive element components respectively made from different optical materials and which has a diffractive optical surface on which diffractive grating grooves are formed on bonded surfaces of the two diffractive element components, and at least one cemented lens component, the third lens group includes at least one achromatic lens component, and a lens surface of the third lens group nearest to an image side is arranged so that a concave surface of the lens surface faces the image side, the microscope objective lens configured such that if f denotes a focal length of the microscope objective lens and f12 denotes a combined focal length of the first lens group and the second lens group, then the microscope objective lens satisfies a condition expressed by
1.5≦|f12/f|≦2.5, and if f denotes a focal length of the microscope objective lens and f3 denotes a focal length of the third lens group, then the microscope objective lens satisfies a condition expressed by
10≦|f3/f|≦20.