JPS55134320A - Liquid level detector - Google Patents

Abstract

PURPOSE:To provide a highly sensitive liquid level detector which permits obtaining a signal representative of a liquid level at a high output level, by subjecting an optical fiber consisting of a core and a clad to heat distortion so as to make uneven an interface between the core and clad, and detecting variations, which are caused by a liquid, in a scattering loss occurring in the uneven portion of the optical fiber. CONSTITUTION:An optical fiber 6 consisting of a core and a clad is bent, and that portion of the core and clad which is in the bent section of the optical fiber 6 is thermally distorted. Thus, an interface between the core and clad is made uneven. As a result, a loss of light propagated through the optical fiber 6 can be reduced to a great extent, and a scattering loss and radiation loss of light occur in the bent section of the optical fiber 6. Consequently, a largely varying signal can be extracted. Thus, a simply constructed, highly sensitive liquid level detector can be obtained.