Abstract: A thin film magnetic head includes an upper magnetic core film and a lower magnetic core film laminated one on another through a magnetic gap layer. The upper and lower magnetic core films are multilayer thin films, respectively, each of which is composed of a plurality of magnetic thin film layers and a plurality of non-magnetic thin film layers, alternately laminated one on another. The magnetic core films and have single domain structures, respectively, and the use of such magnetic core films realizes a thin film magnetic head having high permeability at high frequencies and improved high frequency characteristics and attains high recording density.

Abstract: An infrared film thickness gage for continuous on-line thickness measurement of a plastic film produced by a film blowing process into a tube shape has an infrared source with generally uniform directional radiation characteristics and is concentrically positioned inside the film tube. A photodetector is positioned outside the film tube in confronting relation to the source and receives the infrared rays of different reference and measurement wavelengths after the infrared rays have passed through the tube. Converting means receives the output of the photodetector, and since the film has different known attenuation coefficients for the different wavelengths, the thickness of the film can be determined. By using an infrared source having uniform directional characteristics and a filter to filter out instantaneous background light, measurement errors are substantially reduced or eliminated.

Abstract: A device for measuring the thickness of a thin film or the like is provided using infrared rays. A source of infrared rays is positioned on one side of the film. A disk with two apertures is rotatably mounted between the infrared source and the film, with band-pass filters positioned over the apertures in the disk. A concave hemispherical reflector with a reflector surface facing the film is positioned between the infrared source and the film. A hole is formed in the center of the concave reflector through which the infrared rays pass. A convex reflector is positioned between the film and the concave reflector and has a reflecting surface facing the concave reflector. A light collecting guide with a photoelectric sensor is positioned on the opposite side of the film from the infrared source for measuring the intensity of the infrared rays.