Abstract: A novel magneto-optical modulator is introduced, which used permanent magnet slice, so the tem- perature effect is avoided for the Verdet constant of magneto-optical material. The working principle of the device is described in detail, the ranging of the ZF6, Tb20, Tb25 pushed forward are measured precisely magnetic field is also provided, and the Verdet constants of Lak2, Lak3, in 292 K. So that the study of geomagnetic field imaging technology is and is offered date by this experiment.

Key words: magneto-optic rotation, Verdet constant, temperature effect magneto-optical modulator geomagnetic field imaging