Abstract: An optical module is formed of a first optical block and a second optical block each equipped with a lens the optical axis of which needs to be aligned, the blocks being positioned and secured to each other, and has stepwise positioning means. A positioning means includes spring pieces each having an abutting slope, and edges. Four spring pieces are formed in the second optical block such that their abutting slopes are disposed at four corners of the second optical block. Positioning is implemented when the abutting slopes meet the edges of the first optical block. Another positioning means includes a depressed part and a guide slope formed in one of the two optical blocks and a raised part formed in the other optical block. The raised part is fitted into the depressed part.

Abstract: An optical module is formed of a first optical block and a second optical block each equipped with a lens the optical axis of which needs to be aligned, the blocks being positioned and secured to each other, and has stepwise positioning means. A positioning means includes spring pieces each having an abutting slope, and edges. Four spring pieces are formed in the second optical block such that their abutting slopes are disposed at four corners of the second optical block. Positioning is implemented when the abutting slopes meet the edges of the first optical block. Another positioning means includes a depressed part and a guide slope formed in one of the two optical blocks and a raised part formed in the other optical block. The raised part is fitted into the depressed part.

Abstract: Light from a light source is provided to an optical coupler 14 via a beam splitter 25 having a 1:4 branching ratio and a polarizer 13. Two light beams split by the optical coupler 14 are provided as clockwise and counterclockwise light beams to both ends of an optical fiber coil 16 via phase modulators 15 and 26, respectively. In the phase modulator 15 said light beams are each phase modulated by a modulation signal .phi.(2.pi.f.sub.m t) and in the phase modulator 26 they are each phase modulated by a modulation signal .phi.(2.pi.f.sub.m t-2.pi..tau.f.sub.m) (where .tau. is the time for light to propagate through the optical fiber coil 16). The two light beams having passed through the optical fiber coil 16 are combined by the optical coupler 14 to interfere with each other, and the resulting interference light is provided via the beam splitter 25 to a photodetector 21, the output of which is synchronously detected by the modulation signal.

Abstract: In a waveguide type optical device which has an optical waveguide and modulation electrodes for varying its refractive index, both formed in the top of a substrate and a ferroelectric crystal having a pyroelectric effect, the top of the crystal substrate being parallel to the direction of its spontaneous polarization, conductive films are formed in two surfaces of the crystal substrate which cross the direction of the spontaneous polarization. The conductive films are electrically interconnected to thereby prevent a change in the operating temperature characteristic of the optical device which is caused by the pyroelectric effect of the crystal substrate.

Abstract: In a fiber optic gyroscope in which light from a light source is split into two beams for supply to one and the other end of an optical fiber coil respectively, and the two beams having propagated through the optical fiber coil and emitted the one and the other end thereof are coupled together for supply to a photodetector, there are separately formed on an optical integrated circuit substrate two optical waveguide couplers, each comprising a trunk and a pair of branches extending therefrom. The pair of branches of a first one of the two optical waveguide couplers are connected to the light source and the photodetector, respectively, and the pair of branches of the second optical waveguide coupler are connected to the one and the other end of the optical fiber coil, respectively. The trunks of the first and second optical waveguide couplers are interconnected via a connecting optical fiber.

Abstract: A flat fluorescent lamp having transparent electrodes, transparent glass plates spaced vertically apart and confronting each other, transparent conductive films forming electrodes provided on the outer surface or the inner surface of the glass plates, fluorescent paint layers provided fixedly on the inner side of the glass plates, or on the glass plates via the transparent conductive films by coating the fluorescent paint on the inner surfaces of the glass plates or conductive films, glass frames spaced horizontally close to both ends of the transparent glass plates or the transparent conductive films and fixedly mounted on the glass plates or transparent conductive films, a space surounded by the glass plates or the transparent conductive films and the glass frames for sealing gas, generally an inert gas therein, and lead-in wires clamping one end of the glass plates and the transparent conductive films.