A Mesosphere Magnetic Field Telemetry Device Based on Gated Photon Counting

Abstract

A mesosphere magnetic field telemetry device based on gated photon counting relates to the field of laser remote sensing of mesosphere magnetic field, comprising a continuous wave laser, an acousto-optic modulation unit, a transmitting telescope, a receiving telescope, a detection unit, an FPGA gated photon counting unit and a computer. FPGA is used to generate the pulse signal of laser intensity modulation, and realize the function of gating photon counting. Adjust the gate delay, receive the resonance fluorescence emitted by the neutral atomic layer in the middle layer, and scan the repetition frequency of the pulse to obtain the magnetic resonance signal. Remote detection of the mesosphere magnetic field provides a new tool for mapping the magnetic field structure of Earth's lithosphere and for long-term monitoring of ionospheric currents in polar regions. The interlayer magnetic field measurement scheme based on gated photon counting can only receive echoes from specific highly neutral atomic layers, and is expected to achieve highly resolvable interlayer magnetic field measurements.

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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