MEASURING DEVICES AND METHODS EMPLOYING A DISPERSIVE MEDIUM IN AN OPTICAL RESONATOR

摘要

A measuring system comprises a laser (10) which acts as a source of electromagnetic radiation. The electromagnetic radiation is directed into two resonance cavities (11, 14), formed by mirrors (12, 13) and (15, 16), respectively. Detectors (27, 28) determine when the laser beam in each cavity is resonating in the cavity. One of the resonance cavities contains a dispersive medium (17) whose refractive index also varies in dependence upon the strength of the magnetic field to which the medium (17) is exposed. The beat frequency between the beam in the cavity (11) and the beam in the cavity (14) containing the medium (17) is determined by a detector (19) and gives a measure of the magnetic field to which the medium (17) is being exposed.