Measurement of Linearly Polarized Light Rotation Applied in Atomic Magnetometer

Abstract

The measurement of linearly polarized light rotation is the key technique in atomic magnetometer. It influences the sensitivity of atomic magnetometer directly. The basic principle of polarizer beam splitter detecting was analyzed. The ZF7 optical glass and solenoid were used to generate standard small angle based on Faraday effect. The signal of AC rotational angle was extracted by lock-in amplifier. The experiment proved that the method can measure 8×10-7rad small optical rotation. As the linearly polarized light rotation is 20mrad in atomic magnetometer, the signal to noise ratio reaches 25000.

Suppression of mechanical error in micro-rotation-angle measurement of optical pumped atomic magnetometers

“…By applying two polarizers perpendicular to each other, the angle rotation could be measured with intensity variation. Considering the mechanical error δ between the two polarizers as plotted in figure 1, the rotation angle θ can be calculated through [16][17][18]:…”

“…As a comparison, the results of single modulation in the probe/detection light path or in the pumping light path are studied as a control. The spin-exchange rate of the alkali metal atom is at level of 10 5 sec -1 [18]. Consequently, the modulation frequency of the pump beam is set to 1/2π MHz and the modulation frequency of the probe is set to 2/2πkHz considering the properties of a Faraday rotator or a photo-elastic.…”