A mobile atomic absolute gravimeter NIM-AGRb-1 based on light-pulse atom interferometer has been built, evaluated by the National Institute of Metrology (NIM) China, and participated in the pilot study of the International Comparison of Absolute Gravimeters (CCM.G-K2.2017) held at NIM Changping Beijing in October 2017. The sensitivity of the gravimeter is 44 µGal Hz −1/2 (1 µGal = 10 −8 m s −2 ≈ 10 −9 g) and its instability reaches as small as 0.2 µGal when averaged over 30 000 s. The instrumental and environmental effects were evaluated and corrected with a total uncertainty of 5.2 µGal. The absolute g measured by NIM-AGRb-1 was compared to that of a commercial FG5X-249 optical gravimeter with the two devices operating side by side in the same laboratory and their results agree within −0.2(6.3) µGal. NIM-AGRb-1 also demonstrated continuous operation over a period of more than 500 h.
Nonlinear spectroscopy has become a useful tool in laser cooling, frequency stabilization and so on. We use the 455.5 nm light beam output of an external cavity diode laser to perform the saturation spectroscopy signal and polarization spectroscopy signal on the 6𝑆 1/2 → 7𝑃 3/2 transition in cesium. The measured linewidth of the 𝐹 4 → 4, 5 transition is as narrow as 1.40 MHz and that of the 𝐹 3 → 2, 3 transition is 1.67 MHz. Both of them are very close to the natural linewidth of about 1.2 MHz. Our result is the narrowest measured linewidth of Cs 455 nm saturation spectroscopy signal to our knowledge.
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