| 摘要 |
PURPOSE:To prevent polarized wave fluctuation by an acoustooptical polariscope, from appearing as an uneven display on a display, by allowing a return light to go into the acoustooptic polariscope after passing through a magneto- optical element, and applying an alternating field to the magneto-optical element. CONSTITUTION:A magnetooptic element 13 is placed in a position where return light goes into an acoustooptic deflector 4 after passing through the magneto- optical element 13. When an alternating field of a prescribed frequency is applied to the magnetooptic element 13 by a driving circuit 14, a plane of polarization of the return light passing through the magneto-optical element 13 rotates in accordance with a period of the alternating field. A period of an optical pulse and a period of the alternating field are not synchronized, therefore, whenever the optical pulse is sent to an optical fiber 8, the plane of polarization of the return light rotates at random. In such a way, strength and weakness of a detecting signal of a photodiode 9 by a periodical rotation of the plane of polarization, based on the characteristic of the optical fiber 8 are not saved after an averaging addition processing, and accordingly, unevenness does not appear on a display 12. |
