An ophthalmic surgical microscope includes a beam coupler positioned along an optical path of the surgical microscope between a first eyepiece and magnifying/focusing optics, the beam coupler operable to direct the OCT imaging beam along a first portion of the optical path of the surgical microscope between the beam coupler and a patient's eye (an OCT image being generated based on a reflected portion of the OCT imaging beam). The surgical microscope additionally includes a real-time data projection unit operable to project the OCT image generated by the OCT system and a beam splitter positioned along the optical path of the surgical microscope between a second eyepiece and the magnifying/focusing optics. The beam splitter is operable to direct the projected OCT image along a second portion of the optical path of the surgical microscope between the beam splitter and the second eyepiece such that the projected OCT image is viewable through the second eyepiece.

A varifocal lens includes a first phase plate and a second phase plate which are rotatable relative to each other about an optical axis. The first phase plate includes a plurality of first phase conversion elements, the second phase plate includes a plurality of second phase conversion elements, and the plurality of first phase conversion elements and the plurality of second phase conversion elements are arranged so that light transmitted through the first phase plate and the second phase plate is focused on different positions on the optical axis depending on a relative rotational displacement between the first phase plate and the second phase plate.

A varifocal lens includes a first phase plate and a second phase plate which are rotatable relative to each other about an optical axis. The first phase plate includes a plurality of first phase conversion elements, the second phase plate includes a plurality of second phase conversion elements, and the plurality of first phase conversion elements and the plurality of second phase conversion elements are arranged so that light transmitted through the first phase plate and the second phase plate is focused on different positions on the optical axis depending on a relative rotational displacement between the first phase plate and the second phase plate.

A zoom lens system includes a positive first lens group, a negative second lens group, and positive third and fourth lens groups, in that order from the object side. Upon zooming from the short to long focal length extremities, the first lens group does not move along the optical axis direction, and the second lens group and the third lens group are movable in the optical axis direction. The first lens group includes at least one negative lens element, and the following conditions are satisfied:
d1n<22.85
and
8.0<f3/f2<3.0,
wherein d1n designates the Abbe number, with respect to the d-line, of the negative lens element, which is provided closest to the object side within the first lens group, and f2 and f3 designate the focal lengths of the second and third lens groups, respectively.

A zoom lens system includes a positive first lens group, a negative second lens group, and positive third and fourth lens groups, in that order from the object side. Upon zooming from the short to long focal length extremities, the first lens group does not move along the optical axis direction, and the second lens group and the third lens group are movable in the optical axis direction. The first lens group includes at least one negative lens element, and the following conditions are satisfied:
d1n<22.85
and
8.0<f3/f2<3.0,
wherein d1n designates the Abbe number, with respect to the d-line, of the negative lens element, which is provided closest to the object side within the first lens group, and f2 and f3 designate the focal lengths of the second and third lens groups, respectively.

A varifocal lens includes a first phase plate and a second phase plate which are rotatable relative to each other about an optical axis. The first phase plate includes a plurality of first phase conversion elements, the second phase plate includes a plurality of second phase conversion elements, and the plurality of first phase conversion elements and the plurality of second phase conversion elements are arranged so that light transmitted through the first phase plate and the second phase plate is focused on different positions on the optical axis depending on a relative rotational displacement between the first phase plate and the second phase plate.

A varifocal lens includes a first phase plate and a second phase plate which are rotatable relative to each other about an optical axis. The first phase plate includes a plurality of first phase conversion elements, the second phase plate includes a plurality of second phase conversion elements, and the plurality of first phase conversion elements and the plurality of second phase conversion elements are arranged so that light transmitted through the first phase plate and the second phase plate is focused on different positions on the optical axis depending on a relative rotational displacement between the first phase plate and the second phase plate.

An optical system includes a first lens unit that has positive refractive power, a second lens unit that moves during focusing and that has positive refractive power or negative refractive power, and a third lens unit that has positive refractive power or negative refractive power. The first lens unit, the second lens unit, and the third lens unit are disposed in that order from an object side to an image side. During focusing, an interval between adjacent lens units changes. In the optical system, a focal length f of the entire optical system, a distance LD along an optical axis from a lens surface of the first lens unit that is closest to the object side to an image plane, and focal lengths of positive and negative lenses that are included in the first lens unit are appropriately set.

An optical system includes a first lens unit that has positive refractive power, a second lens unit that moves during focusing and that has positive refractive power or negative refractive power, and a third lens unit that has positive refractive power or negative refractive power. The first lens unit, the second lens unit, and the third lens unit are disposed in that order from an object side to an image side. During focusing, an interval between adjacent lens units changes. In the optical system, a focal length f of the entire optical system, a distance LD along an optical axis from a lens surface of the first lens unit that is closest to the object side to an image plane, and focal lengths of positive and negative lenses that are included in the first lens unit are appropriately set.

The zoom lens consists of, in order from an object side, a first lens group having a positive power, a second lens group having a negative power, a third lens group having a negative power, a stop, a fourth lens group having a positive power, and a fifth lens group having a positive power. During zooming, the first lens group and the fifth lens group remain stationary, and the other lens groups and the stop move. The most image side positive lens is disposed to be closest to the image side in the first lens group. The following conditional expression relating to a partial dispersion ratio gF1p of the most image side positive lens between the g line and the F line and an Abbe number 1p is satisfied:

0.6376<gF1p+0.00171p<0.7.