Abstract: An optical sensor comprising: a light irradiation means for irradiating a linearly polarized light having a wavelength of 740 to 890 nm; a magneto-optical element having a composition of Y.sub.3-X Tb.sub.X Fe.sub.5 O.sub.12 (0.3.ltoreq..times..ltoreq.0.8) for Faraday rotating the linearly polarized light to output a rotated polarized light; and a detecting means for modulating in intensity the rotated polarized light which has been Faraday rotated by the magneto-optical element and detecting a light output of the rotated polarized light from the magneto-optical element. This magneto-optical sensor has a high sensibility and an excellent temperature characteristics under condition of low-magnetic field. When the optical sensor 10 is additionally provided with an electro-optical element having Pockels effect in parallel to the magneto-optical element, it becomes possible to measure not only current intensity but also voltage intensity.

Abstract: An optical sensor comprising: a light irradiation means for irradiating a linearly polarized light having a wavelength of 740 to 890 nm; a magneto-optical element having a composition of Y.sub.3-x Tb.sub.x Fe.sub.5 O.sub.12 (0.3.ltoreq.x.ltoreq.0.8) for Faraday rotating the linearly polarized light to output a rotated polarized light; and a detecting means for modulating in intensity the rotated polarized light which has been Faraday rotated by the magneto-optical element and detecting a light output of the rotated polarized light from the magneto-optical element. This magneto-optical sensor has a high sensibility and an excellent temperature characteristics under condition of low-magnetic field. When the optical sensor 10 is additionally provided with an electro-optical element having Pockels effect in parallel to the magneto-optical element, it becomes possible to measure not only current intensity but also voltage intensity.

Abstract: A field emission cathode which comprises an emitter provided with a sharp point for emission of electrons and a controlling gate electrode is composed of a supporting substrate, an emitter material layer formed of an emitter material, superposed on and attached fast to the supporting substrate, and provided with an emitter hole, an insulator layer so formed on the surface of the emitter material layer as to expose the tip part of the emitter projection therethrough, and an impurity diffusion layer formed on the surface of the insulator layer and enabled to function as an etching stopper layer.

Abstract: A field emitter cold cathode has a substrate possessing a first main surface on one side of itself and a second main surface on the other side of itself and has windows formed in itself. An emitter layer is formed on the first main surface side of the substrate, and has emitters disposed at the positions of the windows. A gate electrode layer is formed on the second main surface side of the substrate. In addition, openings are so formed as to enclose untouched the periphery of at least the leading end part of the emitters.

Abstract: An optical sensor includes: a light irradiation source for irradiating linearly polarized light having a wavelength of 740 to 890 nm; a magneto-optical element having a composition of Y.sub.3-x Tb.sub.x Fe.sub.5 O.sub.12 (0.3.ltoreq..times..ltoreq.0.8) for Faraday rotating the linearly polarized light to output a rotated polarized light; and a detector for modulating in intensity the rotated polarized light which has been Faraday rotated by the magneto-optical element and detecting a light output of the rotated polarized light from the magneto-optical element. This magneto-optical sensor has a high sensibility and excellent temperature characteristics under a condition of low-magnetic field. When the optical sensor 10 is additionally provided with an electro-optical element having a Pockels effect in parallel to the magneto-optical element, it becomes possible to measure not only current intensity but also voltage intensity.