Abstract: A method and apparatus determines the thickness of a copper oxide coating of an object by measuring the quantity of light reflected from the object in at least two wavelength zones, and then determining a value for a relationship between those quantities, for example, the ratio or difference of those quantities. The value is then compared to a predetermined, regular correspondence between such values and copper oxide thicknesses to determine the object's copper oxide thickness.

Abstract: An lighting apparatus including a housing having an opening, a light source received in the housing and a light transmitting-cover fixed at the opening of the housing and through which light rays are projected from the light source. The light transmitting-cover includes a plate made of light transmitting-material and having a first surface and a second surface. Segment lens elements of the same size are arranged on the first and second surface of the plate and formed integrally with the plate. The segment lens elements on the first surface are positioned in face-to-face relation with the segment lens elements arranged on the second surface, thus forming a segment lens. The segment lens elements have a common optical axis and convex surfaces, respectively. The focal lengths defined by these convex surfaces are equal.

Abstract: In a rear projection screen, a pair of light-refracting plates oppose each other. A plurality of first convex lens elements are arranged parallel to each other on one surface of the light-reacting plate, and a plurality of second convex lens elements are arranged parallel to each other on the other surface of the light-refracting plates. Similarly, a plurality of first convex lens elements are arranged parallel to each other on one surface of the light-refracting plate, and a plurality of second convex lens elements are arranged parallel to each other on the other surface of the light-refracting plate. Each pair of opposed first and second convex lens elements is located along a common optical axis thereof. A convex surface of each first convex lens element is located at a focal plane of the corresponding second convex lens element. A convex surface of each second convex lens element is located on a focal plane of the corresponding first convex lens element.

Abstract: A rear projection apparatus for producing an optical image on a surface of a rear transmitting screen in which a convex lens array is formed on both surfaces of the screen, each convex lens formed on one surface of the screen having a corresponding convex lens formed on the other surface of the screen with a common optical axis, the focal point of each convex lens formed on one surface of the screen being on the surface of the each convex lens formed on the to other surface of the screen.

Abstract: An optical refractor comprises a plate made of transparent material and having a first surface and a second surface. Segment lens elements of the same size are arranged on the first and second surface of the plate and formed integrally with the plate. The segment lens elements on the first surface are positioned in face-to-face relation with the segment lens elements arranged on the second surface, thus forming pairs of segment lens element. The segment lens elements have a common optical axis and convex surfaces, respectively. The focal lengths defined by these convex surfaces are equal. The focal point of one of the segment lens elements lies on the convex surface of the other segment lens element, and that of the other segment lens element lies on the convex surface of the first segment lens element.

Abstract: A method and an apparatus for treating fluorescent substances used in illumination lamps or cathode ray tubes for television receivers. A gas plasma is produced by passing a gas through a discharge tube. The gas plasma including the active species are directed so as to bring the active species into contact with the fluorescent substance, the fluorescent substance being placed at a region separated from the plasma producing region.

Abstract: A microwave oven comprising a magnetron for emitting microwaves; a heating chamber body for holding food being heated by microwaves from the magnetron; an infrared ray transmitting section provided in the top wall of the heating chamber body for transmitting infrared rays emitted from the food; an infrared ray detecting device disposed over the infrared ray transmitting section and comprising a horn member and an infrared ray detecting element, the horn member being made of material capable of cutting off microwaves and having a hollow extending toward the heating chamber body into which infrared rays are applied from the food and the infrared ray detecting element being so positioned as to detect infrared rays condensed by the hollow, the hollow having a diameter increasing toward the heating chamber body and a minimum opening size smaller than the wavelength of microwaves and having a spread angle so set that only infrared rays emitted from the food may be allowed to reach the infrared ray detecting element