Abstract: An optical head is disclosed in which a beam from a diode laser is directed onto an optical disc, and a beam reflected from the optical disc is passed through an optical device which forms a plurality of discrete beams of different orders. The beams from the optical device are focussed onto photodetectors, and signals from the photodetectors are used for error detection, tracking, and signal detection. The optical device comprises two diffraction gratings which are supported on a substrate and are separated from each other by a thin film. In order to obtain the advantages of a doubly-periodic structure, the thickness of the thin film between the two gratings is very accurately controlled to be on the order of the wavelength of the incident beam of radiation.

Abstract: An optical device is disclosed for diffracting an incident beam of radiation to form a plurality of discrete diffracted beams of different orders. The optical device comprises two diffraction gratings which are supported on a substrate and are separated from each other by a thin film. In order to obtain the advantages of a doubly-periodic structure, the thickness of the thin film between the two gratings is very accurately controlled to be on the order of the wavelength of the incident beam of radiation.

Abstract: A method is disclosed for making an optical device which is adapted to diffract an incident beam of radiation to form a plurality of discrete diffracted beams of different orders. The optical device comprises two diffraction gratings which are supported on a substrate and are separated from each other by a thin film. In order to obtain the advantages of a doubly-periodic structure, the thickness of the thin film between the two gratings is very accurately controlled to be on the order of the wavelength of the incident beam of radiation.

Abstract: There is disclosed a technique whereby a dielectric grating disposed on a in film that has a surface wave propagating thereon can concentrate the power from this wave into a beam that is either above or below the grating according to the profile of the grating. By this technique, surface waves traveling in different directions can be distinguished and the efficiency of optical beam couplers can be improved, among other applications.

Abstract: A circular symmetrical dielectric antenna structure and feed arrangement provide an omni-directional radiation pattern. The antenna includes a linear dielectric feed section, an integral radiating section having a taper which decreases outwardly, and an excitation means coupling millimeter wave energy to the feed section. The entire structure is circularly symmetrical about a central longitudinal axis. A first embodiment is in the form of a longitudinal dielectric rod having a uniform diameter at the feed and with circular periodically spaced corrugations at the radiating end. A tapered intermediate section has grooves of increasing depth, with the depth being constant at the remainder of the radiating end. A circular waveguide couples energy to a tapered dielectric transition section to provide excitation to the uniform feed end. A second embodiment is in the form of a flat circular disk having tapered radiating ends. A central metal cap limits radiation from the top surface.