Aeromagnetic field vector detecting device and detecting method

Abstract

The invention relates to an aeromagnetic field vector detecting device and a detecting method, a DFB laser which has the same lasing frequency with an alkali metal atom D1 wire is adopted as a pump light source, the light emitted by the DFB laser generates circular polarization pump light polarized alkali metal atoms with free adjustable laser power through an optical isolator, an optical attenuator, a polarizer and a lambda / 4 wave plate, and the atom is made to have macroscopic magnetic moment. A detected weak magnetic field in a y axis direction makes the magnetic moment to generate Larmor precession on an xoz plane around the y axis. The polarization plane rotation of the linearly polarized light caused by circular dichroism of a polarized atom, the pump light is removed, the deflection angle gradually vibrates and attenuates to zero, a zero-cross detection device is adopted to detect the time difference between the time of removing the pump light and the first zero crossing point, the Larmor prescession frequency can be obtained, and a magnetic-field vector value is obtained by dividing the Larmor prescession frequency by a gyromagnetic ratio. According to the invention, the device and the method have the advantages of high magnetic-field vector detection precision, fast response frequency and good repeatability, and are suitable for aeromagnetic field vector detecting mobile platform magnetic measurement.

Description

Technical field: [0001] The invention relates to an aerial geophysical detection device and a detection method, in particular to a magnetic field vector detection device and a detection method based on measuring the macroscopic magnetic moment attenuation frequency of polarized alkali metal atoms. Background technique: [0002] Airborne magnetic survey is used to survey oil and gas and other minerals, and plays an important role in geological survey, mineral survey and earth science research, and is a main method of airborne geophysical prospecting. The high-altitude magnetic field has the following characteristics: the magnetic field strength increases with altitude at a rate of 1 / r 3 The form is reduced, and its value is less than 1nT at an altitude of tens of meters, and it fluctuates in real time due to various reasons (human noise, lightning, solar wind, etc.), so the high-precision, fast-response magnetic field vector measurement method is an important research directi...

AI Technical Summary

Problems solved by technology

When the measured magnetic field changes greatly, there is a problem of frequency lock-out, which is not suitable for mobile platforms; the method of measuring the steady-state DC macroscopic magnetic moment with the continuous action of pump light, the core is to determine the ratio parameter between the steady-state solution of the deflection angle and the measured magnetic field, The determining factor is affected by the accuracy of the calibrated magnetic field, and the measured magnetic field data has a large error, so it is not suitable for the magnetic field vector measurement of the mobile platform

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