A spectrally shearing optical relay system, said relay system being comprised of two halves disposed symmetrically about an aperture stop S, wherein each half comprises a plurality of rotationally symmetric optical elements forming an objective and a com-pound prism comprised of a plurality of dispersing prisms. The compound prisms are located between the objectives and the aperture stop. An imaging device with such an optical relay system is also proposed.

An optical imaging system includes: a first lens group including a plurality of lenses; a second lens group including a plurality of lenses; a first reflecting member disposed on an object side of the first lens group; and a plurality of second reflecting members arranged between the second lens group and an image sensor. One or both of the first lens group and the second lens group is movable along an optical axis, an interval along the optical axis between the first lens group and the second lens group is varied between a first interval and a second interval smaller than the first interval, and as at least one of the first lens group and the second lens group is moved, one or more of the second reflecting members are moved.

An optical imaging system includes: a first lens group including a plurality of lenses; a second lens group including a plurality of lenses; a first reflecting member disposed on an object side of the first lens group; and a plurality of second reflecting members arranged between the second lens group and an image sensor. One or both of the first lens group and the second lens group is movable along an optical axis, an interval along the optical axis between the first lens group and the second lens group is varied between a first interval and a second interval smaller than the first interval, and as at least one of the first lens group and the second lens group is moved, one or more of the second reflecting members are moved.

A condensing objective optical system includes a first lens group having negative refractive power, a second lens group being a focus group having positive refractive power, and a photoacoustic element disposed closest to an object in this order. The photoacoustic element reflects an optical wave from the second lens group toward an object to transmit a photoacoustic wave from the object side. The condensing objective optical system satisfies a specific conditional expression that defines the conditions of the included lens and the condition regarding focusing.

A condensing objective optical system includes a first lens group having negative refractive power, a second lens group being a focus group having positive refractive power, and a photoacoustic element disposed closest to an object in this order. The photoacoustic element reflects an optical wave from the second lens group toward an object to transmit a photoacoustic wave from the object side. The condensing objective optical system satisfies a specific conditional expression that defines the conditions of the included lens and the condition regarding focusing.

An imaging lens includes, in order from the object side, a first lens group that has a negative refractive power and a second lens group that has a positive refractive power. During focusing, only the second lens group moves. The first lens group includes three negative lenses successively in order from a position closest to the object side. Assuming that an open F number is FNo, a maximum half angle of view is ω, a back focal length is Bf, and a focal length of the whole system f, the imaging lens satisfies 0.8<FNo/tan ω<1.9 and 0.3<Bf/(f×tan ω)<1.2.

An imaging lens includes, in order from the object side, a first lens group that has a negative refractive power and a second lens group that has a positive refractive power. During focusing, only the second lens group moves. The first lens group includes three negative lenses successively in order from a position closest to the object side. Assuming that an open F number is FNo, a maximum half angle of view is ω, a back focal length is Bf, and a focal length of the whole system f, the imaging lens satisfies 0.8<FNo/tan ω<1.9 and 0.3<Bf/(f×tan ω)<1.2.

The present disclosure discloses an optical imaging lens assembly, and the optical imaging lens assembly includes, sequentially from an object side to an image side along an optical axis: a first lens having positive refractive power, and at least one subsequent lens having refractive power. An F-number Fno1 of the optical imaging lens assembly satisfies Fno1>3.5, where an object distance is finite, and an F-number Fno2 of the optical imaging lens assembly satisfies Fno2≥1.0, where the object distance is infinite.

An observation optical system for use in observing an image displayed on an image displaying surface, includes, in order from an observation surface side to the image displaying surface side: a first lens having a first transmission reflective surface and a first transmissive surface; and a second lens having a second transmission reflective surface and a second transmissive surface, in which the first lens and the second lens are arranged via an interval interposed therebetween; light from the image displaying surface transmits through the second lens, is reflected by the first transmission reflective surface, is reflected by the second transmission reflective surface, is transmitted through the first lens, and then travels toward the observation surface side; and a focal length of the first lens and a focal length of the observation optical system are appropriately set.

An observation optical system for use in observing an image displayed on an image displaying surface, includes, in order from an observation surface side to the image displaying surface side: a first lens having a first transmission reflective surface and a first transmissive surface; and a second lens having a second transmission reflective surface and a second transmissive surface, in which the first lens and the second lens are arranged via an interval interposed therebetween; light from the image displaying surface transmits through the second lens, is reflected by the first transmission reflective surface, is reflected by the second transmission reflective surface, is transmitted through the first lens, and then travels toward the observation surface side; and a focal length of the first lens and a focal length of the observation optical system are appropriately set.