| 摘要 |
PURPOSE:To enable a magnetic field sensor to be readily used even in a narrow space by a method wherein it is constituted by coiling an optical fiber so that the relative lengths of the upper and lower halves of the coil axis cross-section differ from each other. CONSTITUTION:The magnetic field sensor is constituted in a magnetic field H by using an optical fiber so that the lengths Zu and Zd of the upper half 7 and the lower half 8 of the detecting coil axis cross-section differs from each other as shown in the figure. The upper and lower halves are sections where the lengths of the optical fiber in the traveling direction of light have the same direction component as the direction of the magnetic field and the opposite direction component thereto respectively. The birefringence amount delta1 at either the upper half 7 or the lower half 8 is to be 2mpi+ or -pi/2, and the other to be (2m+1)pi+ or -pi/2. Thereby, because the Faraday rotation of the former is approximately zero, the Faraday rotation of the latter is not canceled. Accordingly, it is possible to detect the intensity of the magnetic field from the product of the rotation F by the magnetic field and the rotation determined substantially by delta1. |
