Optically Pumped Magnetometer Frequency Band Expansion
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Solution Overview
Problem
The existing optically pumped magnetometers have a limited measurable frequency band of magnetism due to signal intensity variations with frequency, leading to insufficient signal strength at certain frequencies, restricting the range of magnetism that can be detected with a sufficient signal-to-noise ratio.
Innovation Solution
An optically pumped magnetometer is designed with a static magnetic field generating unit and a control unit that switches the intensity of the static magnetic field, allowing the frequency band of detectable magnetism to be expanded by altering the precession frequency of alkali metal atoms, thereby enhancing the measurable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed static magnetic field intensity is used in the optically pumped magnetometer, then the signal intensity is sufficient at certain frequencies, but the measurable frequency band of magnetism is limited
Solution Approach 1:
The patent applies the dynamics principle by making the static magnetic field intensity adjustable rather than fixed. The control unit dynamically changes the intensity of the static magnetic field generated by the magnetic field generating unit, allowing the system to adapt to different measurement frequency requirements. This enables the magnetometer to maintain sufficient signal intensity across a broader frequency range by optimizing the magnetic field strength for each specific measurement condition.
Solution Approach 2:
The patent implements parameter changes by varying the intensity of the static magnetic field as a controllable parameter. The control unit modifies this parameter based on the desired measurement frequency, thereby changing the operating characteristics of the magnetometer. This allows the system to expand its measurable frequency band while maintaining adequate signal intensity through systematic parameter adjustment.
2Measurement precision
If the intensity of static magnetic field is increased to improve signal intensity, then signal strength improves, but the frequency range that can be measured effectively decreases
Solution Approach 1:
The system dynamically adjusts the static magnetic field intensity based on the measurement requirements. When measurement of lower frequencies is required, the control unit increases the magnetic field intensity to enhance signal strength. Conversely, for higher frequency measurements, the intensity is reduced to maintain the measurable frequency band. This dynamic adaptation resolves the contradiction between signal strength and frequency range.
Solution Approach 2:
The control unit systematically varies the magnetic field intensity parameter to match the measurement frequency. By establishing a relationship between field intensity and frequency range, the system optimizes signal strength for each frequency band of interest, preventing the trade-off from limiting overall system performance.
3Adaptability or versatility
If the static magnetic field intensity is switched between multiple values, then the measurable frequency band is expanded, but the system complexity increases
Solution Approach 1:
The control unit is designed to perform multiple functions: it not only switches the magnetic field intensity to expand the frequency band but also coordinates the timing of measurements across different field intensities. This multi-functional design consolidates what could be multiple separate control systems into a single unit, minimizing the increase in overall system complexity while achieving the goal of expanding the measurable frequency band.
Solution Approach 2:
The system employs periodic switching of the static magnetic field intensity between multiple predetermined values. This periodic action allows the magnetometer to cycle through different operating conditions, measuring signals at various frequencies systematically. The regular, predictable nature of this switching simplifies the control logic compared to arbitrary or continuous adjustment mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively expands the measurable frequency band of magnetism by switching the static magnetic field intensity, improving the sensitivity and range of magnetic pulse detection without requiring complex averaging processes, thus overcoming the limitations of existing technologies.
Implementation Method 1
The optically pumped magnetometer irradiates the alkali metal in a vapor phase with a pump light to bring the alkali metal into an excited state. The alkali metal in an excited state is in a spin polarized state.
Implementation Method 2
The inclination of the spin polarization axis can be detected by a probe light with which the alkali metal in a vapor phase is irradiated separately from the pump light. The inclination of the spin polarization axis can be detected as a change in polarization angle of the probe light.
Implementation Method 3
The frequency of precession of the atom of the alkali metal which is vaporized and excited by the pump light is determined according to the intensity of the static magnetic field.
Data Source
AI summary
A optically pumped magnetometer includes a cell filled with an alkali metal; a pump light source that generates a pump light; a probe light source that generates a probe light; a signal output unit that obtains an output signal related to magnetism, which is received by the cell, based on the probe light which has passed through the cell; a coil unit that generates a static magnetic field along a pump optical axis in a region of disposition of the cell; and a computer that controls operation of the coil unit. The computer outputs a first control signal to set an intensity of the static magnetic field to a first intensity, and a second control signal to set the intensity of the static magnetic field to a second intensity different from the first intensity.