Abstract: A fiber optic magnetic field sensor employing Faraday effect. The sensor has two pieces of birefringent substance interposed between the ends of optical fibers and a rod lens for effecting polarization separation. In addition, the sensor employs a reflex optical system in which light reciprocates through a Faraday material. Thereby, a magnetic field sensor has been realized which is more compact and lightweight and lower in cost as well as more accurate.

Abstract: Respective end faces of two or more optical waveguides (23 to 29) are connected on one end face of a focussing rod lens (20) and a reflection means (21) having a reflection plane tilted with a specified angle (.alpha.) to the normal plane to the lens axis is disposed behind the other end face of the focussing rod lens (20) and angle of reflection plane of the reflection means (21) is varied by rotating the reflection means (21) around the lens axis (203) or by means of a piezo-electric driving device (30), thereby attaining selective switching of the waveguides (from 23 to selected one of 24 or 29) or varying the amount of rays to be transmitted through the waveguides (23 and 24 of FIG. 4), or thereby modulating the rays. By utilizing a semitransparent filter forming another tilted reflection plane, the amount of attenuation for different wavelength or connection of the waveguides are controlled separately.

Abstract: Respective end faces of two or more optical waveguides (23 to 29) are connected on one end face of a focussing rod lens (20) and a reflection means (21) having a reflection plane tilted with a specified angle (.alpha.) to the normal plane to the lens axis is disposed behind the other end face of the focussing rod lens (20) and angle of reflection plane of the reflection means (21) is varied by rotating the reflection means (21) around the lens axis (203) or by means of a piezo-electric driving device (30), thereby attaining selective switching of the waveguides (from 23 to selected one of 24 to 29) or varying the amount of rays to be transmitted through the waveguides (23 & 24 of FIG. 4), or thereby modulating the rays. By utilizing a semitransparent filter forming another tilted reflection plane, the amount of attenuation for different wavelength or connection of the waveguides are controlled separately.

Abstract: In the firing of a cerium-activated Y.sub.2 O.sub.3 -SiO.sub.2 system phosphor such as Y.sub.2 SiO.sub.5 :Ce and Y.sub.2 Si.sub.2 O.sub.7 :Ce, the improvement of adding BaF.sub.2 in a mol ratio of BaF.sub.2 /Y.sub.2 O.sub.3 of 0.01-0.1 is disclosed which increases the luminosity, emission intensity or both of the phosphor. Phosphors having improved properties are conveniently prepared according to the disclosed process.