In an apparatus in which particles are passed through an optical sensing zone to measure their radiant energy distribution such as, for example, light scattering characteristics for the purpose of identifying the particles, means and a method are provided for deviating the collected light in accordance with predetermined different paths to a plurality of different photodetecting devices. The deviation is effected independently of collection by optical radiant energy transmitting or reflecting means. The different photodetecting devices enable the measurement of energy directed along the particular path which is identified with that device. The paths are established by the deviating means rather than permitted to evolve by the scattering phenomena themselves whereby the photodetecting devices can be located in convenient arrangements and may be conventional in construction. Different forms of the invention combine optical reflection or refraction for collecting the scattered radiant energy with optical reflection or refraction for deviation to achieve different advantages and results.

Optical elements shaped in accordance with preferred analytic functions which permit the elements to be relatively rotated about one or more pivots decentered with respect to an optical axis to simulate the dioptric action of a well corrected rotational lens element of variable power that can be used to maintain focal setting over a large range of object distances. The optical elements can be used in pairs, singly with mirror images of themselves, or they can be incorporated in more elaborate systems to provide focusing action.

A multi-element ophthalmic lens construction is disclosed wherein a plurality of two element lens pairs are bonded together to form an ophthalmic lens. Each pair forming a combination has internally mating, Fresnel reduced, corrector shapes. However, each element of the pair has a different index of refraction whereby each lens pair achieves a desired power.

A five element photographic objective including four elements fixed in a generally symmetric arrangement and a transversely movable refracting plate of preferred shape for maintaining the focal setting of the objective over a large range of object distances. One of the four fixed elements and the refracting plate each include at least one surface whose shape is in a nonrotational aspheric and mathematically describable by a polynomial of at least fifth order.

A plurality of binary diffractive optic lenses are formed in the surface of one substrate and a corresponding plurality of recesses are formed in the surface of another substrate. The binary diffractive optic lenses on one substrate are aligned with the recesses on the other substrate and the two substrates are bonded together. A plurality of individual binary diffractive optic lens cover assemblies are obtained by dicing the two bonded substrates.