Single-beam three-axis SERF atomic magnetometer based on coordinate system rotation.

We propose what we believe to be a new single-beam three-axis spin exchange relaxation free (SERF) vector atomic magnetometer scheme based on coordinate system deflection. A theoretical model for the system response under arbitrary angle deflection was established for the first time, and the system response at different angles was simulated and analyzed. The simulation results show that the system response increases in the direction of the non-sensitive axis and decreases in the direction of the sensitive axis as the deflection angle increases, and the two responses tend to be the same when the angle is deflected to 45-degrees. Experimental measurements were carried out at a deflection angle of 45-degrees and the results showed that the sensitivity of the magnetometer was 55fT/Hz1/2 in the x1-axis, 38fT/Hz1/2 in the y1-axis and 60fT/Hz1/2 in the z1-axis. This single-beam magnetometer can be used to construct a miniaturized and low-cost weak magnetic sensor, which is expected to be used for vector measurement of biomagnetism.

Ultra-small, low-cost, and simple-to-control PSP projector based on SLCD technology.

Demand for ultra-small, inexpensive, and high-accurate 3D shape measurement devices is growing rapidly, especially in the industrial and consumer electronics sectors. Phase shifting profilometry (PSP) is a powerful candidate due to its advantages of high accuracy, great resolution, and insensitivity to ambient light. As a key component in PSP, the projector used to generate the phase-shifting sinusoidal fringes must be ultra-small (several millimeters), low-cost, and simple to control. However, existing projection methods make it difficult to meet these requirements simultaneously. In this paper, we present a modern technique that can be used to fabricate the desired projector. A specifically designed device based on segmented liquid crystal display (SLCD) technology is used to display the projected patterns, and a cylindrical lens is used as the projection lens. The SLCD device can display four sets of specific filled binary patterns, each yielding a sinusoidal fringe, and all four sinusoidal fringes satisfy the four-step phase shift relation. 3D shape measurement experiments verify the performance of the projector. Considering that the size of SLCD devices can be reduced to a few millimeters, the proposed technique can be easily used to manufacture ultra-small, low-cost, and simple-to-control PSP projectors.

Effects of system parameters on a single-beam synthetic gradiometer with a dual-cell structure.

We report a single-beam synthetic gradiometer operated in the spin-exchange-relaxation free (SERF) regime, using the structure of two separate atomic vapor cells spaced 2 cm apart. To improve the capability of the gradiometer in suppressing the common-mode magnetic field noise, we are aiming at investigating the effects of the system parameters on the gradiometer common-mode rejection ratio (CMRR). The mathematical expression for the relationship between the gradiometer CMRR and the two variables including the linewidth ratio and the pumping factor ratio is constructed for the first time, to our knowledge. This means that the CMRR can be optimized by controlling the linewidth and the pumping factor, which is easy to implement in the operation process. As a result, a CMRR of 246 is achieved and a gradiometer sensitivity of 4.5 fT/cm/Hz1/2 is also measured. This method provides a theoretical and experimental basis for the automated operation of gradiometers, and the gradiometer system performance can be tuned to a desired state by simply controlling the linewidth and the incident light intensity.