In a magnetic field measurement apparatus, a light source irradiates a gas cell with linearly polarized light serving as pump light and probe light in a Z axis direction, and a magnetic field generator applies alternating magnetic fields which have the same cycle and different phases to the gas cell in each of X axis and Y axis directions. A calculation controller calculates a magnetic field C (C.sub.x, C.sub.y, C.sub.z) of a measurement region using X axis and Y axis components A.sub.x and A.sub.y of the alternating magnetic fields, and a spin polarization degree M.sub.x corresponding to a measurement value W.sub.? from a magnetic sensor.

A magnetic field based micro-vibration measurement device and a measuring therefore are provided, which are applied in a micro-vibration measurement technical field. Fluxgate sensors and a control processing circuit are included. Each of the fluxgate sensors is disposed with an excitation coil and an induction coil that are mutually corresponding; the control processing circuit includes: an excitation signal generating module, a frequency-selective amplifying module, a phase-sensitive rectifying module, a smooth filtering module an ambient magnetic field acquisition module, and a vibration data statistics module. Excitation coils generate excitation magnetic field signals according to the excitation signal sent from the excitation signal generating module the induction coils are for generating induced current signals according to the receive excitation magnetic field signal and the ambient magnetic field signal. Induced current signals are calculated to obtain ambient magnetic field data after sequentially undergoing selective amplification, rectification and smooth filtering.

A light source unit irradiates a gas cell disposed in a measurement region with linearly polarized light in which the direction of travel is a z-axis direction and the vibration direction of an electric field is a y-axis direction. A polarimeter detects optical characteristics of light passing through the gas cell. A magnetic field generator applies an artificial magnetic field, capable of varying an x-axis component, a y-axis component, and a z-axis component, to the measurement region. A calculation control unit generates a plurality of artificial magnetic fields, calculates a magnetization value or a value corresponding to the magnetization value on the basis of the detection results of the polarimeter, and calculates an original magnetic field present in the measurement region, using an artificial magnetic field when the magnetization value or the value corresponding to the magnetization value satisfies a condition for external value.

Optical fiber based current measuring equipment for measuring the current circulating through a conductor. The equipment includes an interrogator having a light emitter and a light receiver, and a sensing portion close to the conductor, the interrogator and the sensing portion being connected through at least one standard single-mode intermediate fiber. The light emitter of the interrogator is configured to emit sets of at least two polarized light pulses to the sensing portion, the pulses being polarized with a specific degree difference, and the light receiver (4) is configured to determine the current circulating through the conductor depending on the pulses it receives in return from the sensing portion. A method for measuring the current circulating through a conductor with the use of an optical fiber based current measuring equipment is also provided.

In order to measure a voltage, an electro-optic element is placed in an electrical field generated by the voltage, and light is passed from a light source through a Faraday rotator and the electro-optic element onto a reflector and from there back through the electro-optic element and the Faraday rotator, thereby generating a voltage-dependent phase shift between two polarizations of the light. The interference contrast as well as a principal value of the total phase shift between said polarizations are measured and converted to a complex value having an absolute value equal to the contrast and a phase equal to the principal value. This complex value is offset and scaled using calibration values in order to calculate a compensated complex value. The voltage is derived from the compensated complex value.

An implant with magnetic field recognition, such as an implant that recognizes fields generated by a magnetic resonance imaging (MRI) device. The implant includes at least one voltage source, at least one control unit, at least one communication coil and an optical structure with a Faraday element. The optical structure includes at least one first and second polarization filters and at least one light detector.

An inspection device includes a light source, an MO crystal disposed to face a semiconductor device (D), an object lens configured to concentrate the light output from the light source onto the MO crystal, a holder configured to hold the MO crystal, a flexible member interposed between the MO crystal and the holder, and an object lens drive unit configured to cause the MO crystal to contact the semiconductor device (D) by causing the holder to be moved in the optical axis direction of the object lens, wherein, when the MO crystal contacts the semiconductor device (D), the flexible member is bent, so that an incident plane is inclined in a range in which an inclination angle of the incident plane of the light in the MO crystal with respect to a plane orthogonal to the optical axis is less than or equal to an aperture angle.

A few-moded fiber is doped such that spatial modes of a signal exhibit different magnetic-field-dependent effects. Based on these magnetic-field-dependent effects, one can determine the electric current that induced a magnetic field that caused these effects.

A sensor (1, 2, 3, 4, 5, 6, 7, 8) comprising a first diamond substrate (9) with at least one colour centre (15), the sensor (1, 2, 3, 4, 5, 6, 7, 8) further comprising a first piezomagnetic (10) or piezoelectric primary element (11), which primary element (10, 11) is arranged to interact with the colour centre(s) (15) of the first diamond substrate (9).

The invention relates to an optical fiber interferometer comprising a light source (20), a differential phase modulator (16), a signal-processing system (900), a sensing optical fiber (73) having a Verdet constant capable of inducing a non-reciprocal magneto-optic Faraday effect, the interferometer being able to detect a difference in phase of an interferometric beam (300) formed by interference between two polarized light waves (111, 112) that have simultaneously travelled along the optical fiber (73) along a closed optical path, and to deduce therefrom, by means of dividing the phase difference by a scale factor, a value of a magnetic field or a value of an electric current flowing in an electric conductor (120). According to the invention, the signal-processing system (900) is suitable for measuring a variation in power contrast of one portion of the interferometric beam and to deduce, from the variation in contrast, a measurement of variation of the scale factor.