Intermediate layer magnetic field remote sensing device based on gated photon counting

Abstract

The invention provides an intermediate layer magnetic field remote sensing device based on gated photon counting, and relates to the field of intermediate layer magnetic field laser remote sensing. The device comprises a continuous wave laser (1), an acoustic-optical modulation unit (2), an emission telescope (3), a reception telescope (4), a detection unit (5), an FPGA gated photon counting unit(6) and a computer (7). A pulse signal modulated by laser intensity is generated by employing an FPGA, and the function of gated photon counting is realized. Gated time delay is adjusted, resonance fluorescence emitted by a neutral atom layer of an intermediate layer is received, the repetition frequency of a pulse is scanned, and a magnetic resonance signal is obtained. The magnetic field of theintermediate layer is remotely detected to provide a new tool for drawing of a magnetic field structure of an earth lithosphere and long-term monitoring of the ionosphere current of a polar region. The intermediate layer magnetic field measuring scheme based on gated photon counting can only receive echo waves from the neutral atom layer at the specific height, and the measurement of the magneticfield of the intermediate layer with distinguishable height can be realized.

Description

technical field [0001] The invention belongs to the field of interlayer magnetic field laser remote sensing, and in particular relates to an interlayer magnetic field telemetry device based on gated photon counting. Background technique [0002] Based on the neutral sodium atomic layer (80-110km) naturally existing in the middle layer and the high-power yellow laser developed for the sodium laser guide star technology, the long-distance detection scheme of the magnetic field in the sodium layer was proposed in 2011. This scheme uses an amplitude-modulated circularly polarized laser to pump the sodium atoms in the middle layer. The magnetic moment of the sodium atoms precesses around the local magnetic field at the Larmor frequency. The ground-based large-aperture telescope is used to detect the resonant fluorescence returned by the sodium atoms with the modulation frequency. When the modulation frequency is consistent with the Larmor precession frequency of sodium atoms, the...

AI Technical Summary

Problems solved by technology

However, under most experimental conditions, the resonant fluorescence emitted by the sodium atoms in the sodium layer travels hundreds of kilometers, and very little reaches the receiving telescope. The phase-sensitive detection technology is not applicable when the echo photon rate is too low

Because the photon rate is too low for filtering to produce a continuous signal, it no longer provides reasonable phase information, making demodulation impossible

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