Abstract: A spherical lens of graded refractive index distribution comprises a core of uneven refractive index of the shape of a sphere or hemisphere and a clad of the shape of a spherical shell and a rod clad, with the two clads disposed on the periphery of the core. By the combination of the core showing negative aberration characteristic and the spherical-shell type clad and the rod clad both showing positive aberration characteristic, there can be formed a lens of corrected aberration. This lens suits combination or integration with other elements and permits easy manufacture of clads. It also provides effective convergence of beams of light desirable for use in an optical pickup, for example.

Abstract: An optical waveguide for transmission of light in the middle infrared band is produced by having its clad part formed of glass consisting preponderantly of germanium dioxide and its core part left unfilled.

Abstract: An optical information processing apparatus comprises an information recording medium, a semiconductor laser diode for issuing a laser beam and an optical system adapted to direct the issued laser beam from the semiconductor laser diode toward the information recording medium and then return the reflected laser beam from the medium to the diode and provided with means capable of rotating the plane of polarization of the reflected laser beam from the medium by 90.degree. relative to the plane of polarization of the issued laser beam.

Abstract: A cladded lens having an uneven refractive index comprises a spherical core having a graded refractive index and producing negative lateral aberration and a cladding producing positive lateral aberration. The aberrations of the core and the cladding are canceled by each other to be considerably corrected. Such a cladded lens is especially effective for optical communication and optical recording-regenerating as in PCM technology.

Abstract: Disclosed is an optical memory playback apparatus using an electroluminescent semiconductor element as a combination light source and sensor, which apparatus permits information in an information storage medium to be reproduced in the form of variation in electrical characteristics of the semiconductor element by causing a beam of light issuing from the electroluminescent semiconductor element to be directed to the information storage medium, allowing the light reflected by the information storage medium to impinge on the semiconductor element for thereby inducing variation in the optical and electrical characteristics of the semiconductor element owing to the self-coupling effect.

Abstract: Method for producing electrical energy by means of a liquid crystal device having opposite electrode plates between which a liquid crystal is inserted and at least one of which is transparent. The opposite electrode plates include asymmetrical electrodes thereon, at least the electrodes on the transparent plate being transparent. When a voltage is applied across any electrodes of the opposite plates an optical display is provided and when a light is directed to any selected transparent electrodes a voltage is induced between the transparent electrode and the corresponding electrodes on the other plate, to thereby provide a photo-electric converting property which can be used for display, position determination and logic operations etc. When a liquid crystal material which is a mixture of the compounds .rho.-methoxybenzal-.rho.-amino-.alpha.-methyl-cinnamic acid n-propyl-ester, .rho.-methoxybenzal-.rho.-acetoxyaniline, .rho.,.rho.