2D microscopy of magnetic field with high spatial resolution is realized using atomic vapor cell and digital micro mirror device. Cesium atom spins are polarized and measured using an elliptically polarized light simultaneously. The Allen variance of the field measurement is characterized to be from 18pT @ 109μm to 8pT @ 438μm.
Ultra-sensitive multi-channel optically pumped atomic magnetometers based on the spin-exchange relaxation-free (SERF) effect are powerful tools for applications in the field of magnetic imaging. To simultaneously achieve ultra-high spatial resolution and ultra-high magnetic field sensitivity, we proposed a high-resolution multi-channel SERF atomic magnetometer for two-dimensional magnetic field measurements based on a digital micro-mirror device (DMD) as the spatial light modulator for a single vapor cell. Under the optimal experimental conditions obtained via spatial and temporal modulation of the probe light, we first demonstrated that the average sensitivity of the proposed 25-channel magnetometer was approximately 25fT/Hz 1/2 with a spatial resolution of 216µm. Then, we measured the magnetic field distribution generated by a gradient coil and compared the experimentally obtained distributions with those calculated via finite element simulation. The obtained g value of 99.2% indicated good agreement between our experimental results and the theoretical calculations, thereby confirming that our proposed multi-channel SERF magnetometer was effective at measuring magnetic field distributions with an ultra-high spatial resolution.
Magnetic field source localization and imaging happen at different scales. The sensing baseline ranges from meter scale, such as magnetic anomaly detection, to centimeter scale, such as brain field imaging, to nanometer scale, such as the imaging of a magnetic skyrmion and single cell. Here, we show how an atomic vapor cell can be used to realize a baseline of 109.6 μm with a magnetic sensitivity of 10 pT/Hz1/2 @0.6–100 Hz and a dynamic range of 2062–4124 nT. We used a free induction decay (FID) scheme to suppress low-frequency noise and avoid scale factor variation for different domains due to light non-uniformity. The measurement domains are scanned by a digital micromirror device. The currents of 22, 30, 38, and 44 mA are applied in the coils to generate different fields along the pumping axis, which are measured respectively by fitting the FID signals of the probe light. The residual fields of every domain are obtained from the intercept of linearly fitting of the measurement data corresponding to these four currents. The coil-generated fields are calculated by deducting the residual fields from the total fields. The results demonstrate that the hole of shield affects both the residual and the coil-generated field distribution. The potential impact of field distribution measurement with outstanding comprehensive properties of spatial resolution, sensitivity, and dynamic range is far-reaching. It could lead to capability of 3D magnetography for small things and/or organs in millimeter or even smaller scale.
We describe a method for measuring the spin spatial frequency response in a Cs vapor cell by using a digital micro-mirror device (DMD) to modulate the pumping light both spatially and temporally. An equivalent space-alternative magnetic field is created by this way. The pumping light through the Cs vapor cell is measured and analyzed in spatial frequency domain. We obtain the spatial frequency response of the Cs vapor cell from 1.4 cm-1to 364.9 cm-1. The theoretical results of the spatial frequency response according to Fick's second diffusion law agree with the experimental results. This method provides an alternate approach for spatial characterization and three-dimensional imaging of spins.
In recent years, sensors based on hot atomic vapor cells have emerged as a compact and highly sensitive means of measuring magnetic fields. Such sensors have been deployed in the field for the measurement of, e.g., biological systems, representing a promising practical application of quantum technologies. However, it remains challenging to obtain high-resolution magnetic field images from these sensors, and in most cases, the spatial resolution of the system is limited by the sensor size. Here, we demonstrate the combination of single-pixel imaging (SPI) techniques with an atom vapor Faraday magnetometer to achieve microscopic magnetic field imaging. We demonstrate magnetic field imaging with a spatial resolution of ≈ 62.5 μm, limited only by the resolution of our digital micromirror device projection system and the absence of magnetic shielding in our experimental setup.
The spin-exchange relaxation-free (SERF) atomic magnetometer has high sensitivity for magnetic field measurement, and is of great significance in frontier physics research, biomagnetic detection and other fields. In recent years, as one of the important development directions, its high spatial resolution and multi-channel magnetic field detection capabilities have been further extended. In this paper, based on the three-axis in-situ magnetic field zeroing method (MFZM), the accurate measurement of three-axis static magnetic field is realized, and the using of the digital micro-mirror device (DMD) further supports the measurement of two-dimensional three-axis magnetic field distribution in a specific area. Then, the experimental system was set up and realized the three-axis magnetic field measurement of 25 points within the 4 mm × 4 mm two-dimensional measurement range, and the resolution of each point is a square area with a side length of 0.8 mm. The proposed method based on the SERF atomic magnetometer can measure the triaxial magnetic field in the internal micro-regions in the magnetic field coil, magnetic shield, etc., helping the analysis and evaluation of the high-resolution magnetic field distribution.
Abstract The polarization of light affected by the birefringence of optical elements, such as vapor cell walls, mirrors, and windows, may introduce systematic errors that can be minimized by precisely measuring and correcting the light polarization with a highly sensitive atomic polarimeter. In high precision measurements, it is necessary to measure the light polarization with a high precision where the light interacts with atoms. However, it is inconvenient or even impossible to use the presented method to measure the light polarization, for example, in a cell or cavity. We present a precise and relatively straightforward method to measure the light polarization based on a cesium (Cs) atomic magnetometer configuration. The pump-probe scheme is involved in our experiment. The pump light polarizes atomic spins and the probe light measures the spins polarization. The optical rotation of the probe light significantly depends on the pump light ellipticity, which can be used to measure the light polarization with a high precision. In our work, we present a method to measure the pump light ellipticity with a sensitivity of 2.1 × 10 −8 rad Hz −1/2 for linearly polarized light, which has approximately an order of magnitude improvement than previous research results.