An image pickup apparatus includes an image forming optical system having an aperture stop, a first lens, and a second lens, and an imager having a light-receiving surface that is curved to be concave toward the image forming optical system, and a relative partial dispersion for a medium of the first lens differs from a relative partial dispersion for a medium of the second lens, and when a straight line indicated by θgF.sub.LA=α×υd.sub.LA+β.sub.LA (where α=−0.00163) has been set, θgF.sub.LA and υd.sub.LA for the medium of the first lens are included in both of an area determined by the following conditional expression (1) and an area determined by the following conditional expression (2), and

the following conditional expression (3) is satisfied:

0.68<β.sub.LA   (1),

υd.sub.LA<50   (2), and

0<|f/R.sub.img|≦1.5   (3).

The invention provides an environment-friendly optical glass with excellent negative anomalous dispersion performance and an optical element. The optical glass with excellent negative anomalous dispersion performance contains 0-5% of Nb.sub.2O.sub.5, exclusive of TiO.sub.2 and F, wherein the relative partial dispersion Pg, F of the optical glass is less than 0.57, and the negative anomalous dispersion ΔPg, F is less than and equal to −0.008. There is no need to add any non-environmentally friendly element into the optical glass provided by the present invention, with the refractive index of 1.60-1.65, the Abbe number of 40-46, and the negative anomalous dispersion ΔPg, F of generally less than −0.01. Therefore, the optical glass, with excellent negative anomalous dispersion performance and environmental performance, is applicable to be extensively applied to digital camera, digital video, camera phone, etc.

Embodiments provide an image pickup lens including a first lens to a fourth lens arranged in sequence from an object side to an image side, the first lens to the fourth lens each having refraction. The first lens and the second lens have negative refraction. The first lens has a second surface facing the image side, and a ratio of an effective radius to a radius of curvature in relation to the second surface is less than 0.96. The first lens, the second lens, and the fourth lens are formed of plastic.

Improved fluoresced imaging (FI) endoscope devices and systems are provided to enhance use of endoscopes with FI and visible light capabilities. An endoscope device is provided for endoscopy imaging in a white light and a fluoresced light mode. A relay system includes an opposing pair of rod lens assemblies positioned symmetrically with respect to a central airspace. The rod lens assemblies include a meniscus lens positioned immediately adjacent to a central airspace and with the convex surface facing the airspace, a first lens having positive power with a convex face positioned adjacent to the inner face of the meniscus lens, a rod lens adjacent to the first lens having positive power and an outer optical manipulating structure selected from various designs providing chromatic aberration correction.

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.

One example includes an optical element. The optical element includes a first optical material structure comprising a first index of refraction across a frequency spectrum. The optical element also includes a second optical material structure configured to exhibit an index anomaly corresponding to a change in index of refraction from the first index of refraction to a second index of refraction across a portion of the frequency spectrum and a change from the second index of refraction to the first index of refraction along the frequency spectrum. The optical element further includes a diffractive interface corresponding to a non-planar material contact junction between the first optical material structure and the second optical material structure. The diffractive interface can be configured to manipulate in a predetermined manner an optical beam having an optical path through the diffractive interface and having a frequency in the portion of the frequency spectrum.

An optical system (LS) includes lenses (L22,L23) satisfying the following conditional expressions,

νdLZ<35.0, and

0.702<θgFLZ+(0.00316×νdLZ), where νdLZ: Abbe number of the lens with reference to d-line, and θgFLZ: a partial dispersion ratio of the lens, wherein θgFLZ is defined by the following expression,

θgFLZ=(ngLZ−nFLZ)/(nFLZ−nCLZ). wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.

An optical system includes a first relay rod of a first material, a second relay rod of a second material, different from the first material, and a lens between the first and second relay rods.

The zoom lens includes, in order from object side to image side, a positive first lens unit, a negative second lens unit, a positive third lens unit, and a rear lens group including at least one lens unit, in which intervals between adjacent lens units are changed during zooming. The third lens unit includes at least two negative lenses and at least three positive lenses. An average value of partial dispersion ratios of two negative lenses having strongest refractive powers of the at least two negative lenses, an average value of partial dispersion ratios of three positive lenses having strongest refractive powers of the at least three positive lenses, an average value of Abbe numbers of the two negative lenses, an average value of Abbe numbers of the three positive lenses, a back focus, and a focal length of zoom lens at wide angle end are appropriately set.

A pair of eyeglasses may include one or more adjustable lenses that are each configured to align with a respective one of a user's eyes. The adjustable lenses may include a foveated liquid crystal adjustable lens stacked with a non-liquid-crystal adjustable lens such as a fluid-filled lens or an Alvarez lens. The foveated adjustable lens may include electrically modulated optical material such as one or more liquid crystal cells. The liquid crystal cells may include arrays of electrodes that extend along one, two, three, four, or more than four directions. Control circuitry may apply control signals to the array of electrodes in each liquid crystal cell to produce a desired phase profile. Each lens may be foveated such that portions of the lens within the user's gaze exhibit a different phase profile than portions of the lens outside of the user's gaze.