(under subclass 668) Subject matter wherein the lens comprises four or more sections (i.e., components), each containing two refractive surfaces arranged in series along the optical axis of the lens with their optical centers in alignment thereon, their planes perpendicular to such axis and their axially extreme refracting surfaces so spaced along the optical axis that parallel light rays upon entering and passing through all of such components are refracted to a focus no more than one time.
(1) Note. The term "component" as applied to a lens designates either (1) a single transparent mass of refractive material having two opposed refracting surfaces or (2) a grouped plurality of such masses arranged in series along the optical axis of the lens with their adjacent refracting surfaces either in full overall contact or in spaced parallel relation with the spacing being of such small magnitude that does not enter into the lens computations.
(2) Note. The two refractive surfaces of a "component" comprising a single mass or the two axially extreme refracting surfaces of a "component" comprising a plurality of masses have at least a portion thereof axially air-spaced from all other adjacent refracting surfaces that may be present in the lens.
(3) Note. The axial dimension of the air-spacing between either the opposed surfaces of the single mass "component" or the axially extreme surfaces of the "component" grouped plurality of masses, and the other adjacent refracting surfaces that may be present in the lens must be of sufficient magnitude to enter into the lens computations in order to limit the axial extent of the lens component.
SEE OR SEARCH THIS CLASS, SUBCLASS:
643+, for eyepieces having four or more components.
648+, for field curvature shaping lenses having four or more components. 656+, for microscope objectives having four or more components.
708+, for nonspherical surface lens systems having four or more components.
726+, for lens systems with reflecting elements having four or more components.
745+, for telephoto lenses having four or more components.
749+, for wide angle lenses having four or more components.
754+, for multiple component lenses in general which have four or more components.
