Key Laboratory of Quantum Precision Measurement of Zhejiang Province, College of Science, Zhejiang University of Technology, Hangzhou 310023, China.
Sensors (Basel). 2023 May 25;23(11):5071. doi: 10.3390/s23115071.
When the initial size of an atom cloud in a cold atom interferometer is negligible compared to its size after free expansion, the interferometer is approximated to a point-source interferometer and is sensitive to rotational movements by introducing an additional phase shear in the interference sequence. This sensitivity on rotation enables a vertical atom-fountain interferometer to measure angular velocity in addition to gravitational acceleration, which it is conventionally used to measure. The accuracy and precision of the angular velocity measurement depends on proper extraction of frequency and phase from spatial interference patterns detected via the imaging of the atom cloud, which is usually affected by various systematic biases and noise. To improve the measurement, a pre-fitting process based on principal component analysis is applied to the recorded raw images. The contrast of interference patterns are enhanced by 7-12 dB when the processing is present, which leads to an enhancement in the precision of angular velocity measurements from 6.3 μrad/s to 3.3 μrad/s. This technique is applicable in various instruments that involve precise extraction of frequency and phase from a spatial interference pattern.
当冷原子干涉仪中原子云的初始尺寸与自由膨胀后的尺寸相比可以忽略不计时，可以将干涉仪近似为点源干涉仪，并通过在干涉序列中引入附加的相位剪切来对旋转运动产生敏感。这种对旋转的敏感性使垂直原子喷泉干涉仪能够测量角速度，除了传统上用于测量的重力加速度之外。角速度测量的准确性和精度取决于通过对原子云的成像检测到的空间干涉图案从频率和相位的正确提取，这通常受到各种系统偏差和噪声的影响。为了提高测量精度，基于主成分分析的预拟合过程被应用于记录的原始图像。当存在处理时，干涉图案的对比度提高了 7-12dB，这导致角速度测量的精度从 6.3μrad/s 提高到 3.3μrad/s。该技术适用于各种涉及从空间干涉图案中精确提取频率和相位的仪器。
