Liquid immersion lens system and optical apparatus using the same

Claim 2

A low magnification liquid immersion objective lens system which uses an immersion liquid having a refractive index ND within a range defined by a condition (1) shown below, comprising in order from the object side, a first lens unit having positive refractive power and at least another lens unit, and satisfying the following conditions (2), (3) and (4): 1.34≦ND≦1.80  (1) β≦15  (2) WDL≦0.35 mm  (3) | f·β/fG 1 |≦40  (4) wherein a reference symbol β represents a magnification of said objective lens system, a reference symbol WDL designates a working distance of said objective lens system, a reference symbol fG 1 represents a focal length of the first lens unit and a reference symbol f designates a focal length of said objective lens system.

Claim 3

A low magnification liquid immersion objective lens system which uses an immersion liquid having a refractive index ND within a range defined by a condition (1) shown below, comprising in order from the object side, a first lens unit having positive refractive power; a second lens unit having negative refractive power; and a third lens unit having positive refractive power, and satisfying the following conditions (2), (3) and (4): 1.34≦ND≦1.80  (1) β≦15  (2) WDL≦0.35 mm  (3) | fG 3 / f|≦ 5  (4) wherein a reference symbol β represents a magnification of said objective lens system, a reference symbol WDL designates a working distance of said objective lens system, a reference symbol fG 3 represents a focal length of the third lens unit and a reference symbol f designates a focal length of said objective lens system.

Claim 4

A low magnification liquid immersion objective lens system which uses an immersion liquid having a refractive index ND within a range defined by a condition (1) shown below, comprising in order from the object side, a first lens unit having positive refractive power; a second lens unit having negative refractive power; and a third lens unit having positive refractive power, and satisfying the following conditions (2), (3) and (4): 1.34≦ND≦1.80  (1) β≦15  (2) WDL≦0.35 mm  (3) | fG 3 / f|≦ 5  (4) wherein a reference symbol β represents a magnification of said objective lens system, a reference symbol WDL designates a working distance of said objective lens system, a reference symbol fG 3 represents a focal length of the third lens unit and a reference symbol f designates a focal length of said objective lens system.

Claim 5

A low magnification liquid immersion objective lens system which uses an immersion liquid having a refractive index ND within a range defined by a condition (1) shown below, comprising in order from the object side, a first lens unit having positive refractive power; and a second lens unit having negative refractive power, and satisfying the following conditions (2), (3) and (4): 1.34≦ND≦1.80  (1) β≦15  (2) WDL≦0.35 mm  (3) | f·β/fG 1 |≦20  (4) wherein a reference symbol β represents a magnification of said objective lens system, a reference symbol WDL designates a working distance of said objective lens system, a reference symbol fG 1 represents a focal length of the first lens unit, and a reference symbol f designates a focal length of said objective lens system.

Claim 6

A low magnification liquid immersion objective lens system which uses an immersion liquid having a refractive index ND within a range defined by a condition (1) shown below, comprising in order from the object side, a first lens unit having positive refractive power; and a second lens unit having negative refractive power, and satisfying the following conditions (2), (3) and (4): 1.34≦ND≦1.80  (1) β≦15  (2) WDL≦0.35 mm  (3) | f·β/fG 1 |≦20  (4) wherein a reference symbol β represents a magnification of said objective lens system, a reference symbol WDL designates a working distance of said objective lens system, a reference symbol fG 1 represents a focal length of the first lens unit, and a reference symbol f designates a focal length of said objective lens system.

Claim 7

The liquid immersion objective lens system according to claim 1 comprising a plane parallel plate disposed at an object side location which is to be brought into contact with the immersion liquid.

Claim 8

The liquid immersion objective lens system according to claim 2 comprising a plane parallel plate disposed at an object side location which is to be brought into contact with the immersion liquid.

Claim 9

The liquid immersion objective lens system according to claim 3 comprising a plane parallel plate disposed at an object side location which is to be brought into contact with the immersion liquid.