| 摘要 |
<p>PURPOSE:To enable magnetic field to be measured highly accurately within a wide temperature range by restricting fluctuation of sensitivity for temperature by detecting difference in quantity of light which is transmitted through two magnetic garnet films with a different film thickness. CONSTITUTION:Light with a wavelength lambda which is divided by a half mirror 21 enters detection parts 40 and 50, is transmitted through magnetic garnet films 42 and 52 whose film thickness is d1 and d2 respectively, is detected by light detectors 6 and 7, difference in quantity of light which is obtained by a subtraction circuit 8 becomes a sensor output I, and is converted to strength of magnetic field. When (GdBi)3 (FeAlGa)5O12 is used for the garnet films 42 and 52, a film thickness d1 set to approximately 90 mum and d2 is set to 195 mum so that change in senser sensitivity for temperature becomes minimum, gain is adjusted so that output ratio of detectors 6 and 7 becomes 3.0, and magnetic field is changed by + or -40Oe within a temperature range of -20 - +60 deg.C, the sensor output I namely change in sensor sensitivity, is kept to be within + or -1.5% and to be flat and further a high sensitivity is achieved, thus enabling magnetic field to be measured with improved accuracy.</p> |
