Abstract: The ophthalmic optical system is configured to apply an angular scanning light ray to an eye. M=|?out/?in| is defined, where ?in represents an angle between an incident light ray to the ophthalmic optical system and an optical axis of the ophthalmic optical system, and ?out represents an angle between an exiting light ray exiting from the ophthalmic optical system toward the eye and the optical axis. The ophthalmic optical system satisfies a conditional expression Mpar<Mmax, where Mpar represents M in a case that the incident light ray is a paraxial ray, Mmax represents M in a case that the incident light ray is a ray of a maximum angle of win.

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the larges.

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the largest.

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the largest.

Abstract: An imaging lens (PL) has an image surface (I) curved to have a concave surface facing an object and consists of, in order from the object along an optical axis (Ax): a front group (Ga) including four lenses (L1 to L4); and a back group (Gb) including a single lens (L5). The following conditional expression is satisfied. 0.25<Dab/TL<0.50 0.30<La/TL<0.55 where, Dab denotes a distance between the front group (Ga) and the back group (Gb) on the optical axis, La denotes a length of the front group (Ga) on the optical axis, and TL denotes a total length of the imaging lens (PL) (a distance between a vertex of a lens surface closest to the object and an axial image point corresponding to an infinite distant object).

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the larges

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the largest.

Abstract: An objective lens OL comprises: a first lens group G1 disposed on an object side, having positive refractive power as a whole and having a positive lens (plano-convex lens L1) which is disposed closest to the object and of which lens surface closest to the object is a plane or a surface having a low curvature, and at least one cemented lens (cemented lens CL12 or the like); a second lens group G2 disposed on an image side, having negative refractive power as a whole, and having a concave surface facing the image and a concave surface facing the object, which face each other; and a diffractive optical element GD in which two diffractive element constituents made from different optical materials are cemented, which has a diffractive optical surface D formed with diffraction grating grooves on the cemented surface, and which is disposed closer to the object than a position where a principal ray crosses the optical axis.

Abstract: Provided is a microscope optical system in which the occurrence of flare due to unnecessary-order diffracted light exited from a diffractive optical element is suppressed. A microscope objective lens MS is configured by including an objective lens OL which has a diffractive optical element GD and converts light from an object into a substantially parallel light flux, and a second objective lens IL which forms an image of the object by focusing the substantially parallel light flux from the objective lens OL, and is configured such that, in case where an m-th order of diffracted light from the diffractive optical element GD is used for the image formation, the following expression is satisfied: |?|>tan?1(0.06/D) when the light of a maximum NA emitted from the object located on an optical axis enters the diffractive optical element.

Abstract: An objective lens OL comprises: a first lens group G1 disposed on an object side, having positive refractive power as a whole and having a positive lens (plano-convex lens L1) which is disposed closest to the object and of which lens surface closest to the object is a plane or a surface having a low curvature, and at least one cemented lens (cemented lens CL12 or the like); a second lens group G2 disposed on an image side, having negative refractive power as a whole, and having a concave surface facing the image and a concave surface facing the object, which face each other; and a diffractive optical element GD in which two diffractive element constituents made from different optical materials are cemented, which has a diffractive optical surface D formed with diffraction grating grooves on the cemented surface, and which is disposed closer to the object than a position where a principal ray crosses the optical axis.

Abstract: An immersion type microscope objective lens OL includes, in order from a cover plate C side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens. The second lens group G2 includes at least two achromatic lenses. The third lens group G3 includes, in order from the object side, an achromatic lens CL31 having a strong concave surface facing an image side, and an achromatic lens CL32 having a strong concave surface facing the object side.

Abstract: An objective lens OL includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a diffractive optical element GD forming a diffractive optical surface D thereon, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens and the most object side surface thereof forms a concave surface facing the object. The second lens group G2 includes at least one cemented lens. The third lens group G3 includes at least one cemented negative lens. In the objective lens OL, a principal ray crosses an optical axis between the second lens group G2 and the third lens group G3, and in the diffractive optical element GD, the diffractive optical surface D is disposed in the vicinity of the position where the principal ray crosses the optical axis.

Abstract: An immersion type microscope objective lens OL includes, in order from a cover plate C side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens. The second lens group G2 includes at least two achromatic lenses. The third lens group G3 includes, in order from the object side, an achromatic lens CL31 having a strong concave surface facing an image side, and an achromatic lens CL32 having a strong concave surface facing the object side.

Abstract: An objective lens OL includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a diffractive optical element GD forming a diffractive optical surface D thereon, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens and the most object side surface thereof forms a concave surface facing the object. The second lens group G2 includes at least one cemented lens. The third lens group G3 includes at least one cemented negative lens. In the objective lens OL, a principal ray crosses an optical axis between the second lens group G2 and the third lens group G3, and in the diffractive optical element GD, the diffractive optical surface D is disposed in the vicinity of the position where the principal ray crosses the optical axis.