| 摘要 |
<p>PURPOSE:To obtain a high-accuracy sensor while reducing the temperature coefficient of the sensitivity of a sensor by adjusting the angle of rotary polarization due to the optical path length of specific single crystal or the phase difference of a wavelength plate. CONSTITUTION:Passing light 7 from a polarizer 1 has the plane 8 of polarization and is so adjusted that the light 7 is perpendicular to the direction 9 of an analyzer 4 in the case of passing through a 1/4 wavelength plate 3, thereby minimizing the light 7 entering a detector 10. When an AC voltage 5 is applied to a material 2, the polarization state of the passing light of the wavelength plate 3 changes to increase the quantity of the passing light of the analyzer 4, and the increase is detected by the detector 10. The phase difference of the wavelength plate 3 is set within a range shown by an expression II when the value satisfying an equation I is set to DELTAcomp for the angle phi of rotary polarization on the optical path of Bi12GeO20 or within a range satisfying an expression III when the value satisfying the equation I is set to phicomp for the phase difference DELTA. In the equation I, alpha is the temperature coefficient of the birefringence of the wavelength plate 3 and beta is the temperature coefficient of rotary polarizing ability of the single crystal 2.</p> |
