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Temperature dependent relaxation time of 87Rb atoms, namely the longitudinal relaxation lifetime T1 and the transverse relaxation lifetime T2 are studied respectively by using the Franzen method and by measuring the optical rotation of a weak, linearly polarized probe light. Although the Franzen measurement in this work is taken with a weak probe light, the absorption of probe light can still destroy the spin polarization of 87Rb atoms to a certain degree. However, a longer relaxation time of T2 can be well achieved by measuring the optical rotation of linearly polarized light under 6 GHz detuning along the direction of red light. Results show that both T1 and T2 obey an exponential decay with temperature, and the temperature dependent decaying rate of relaxation is respectively 27.8 for T1 and 25.0 for T2, indicating that temperature playing a similar role in the reaction to T1 and T2.

In this paper, the changes in chromaticity of LED lamps given by online test during accelerated aging under thermal stress were studied. Firstly, two online accelerated aging tests of a same type of lamps were conducted, with one test at the temperature of 60 ℃ and another at the temperature of 80 ℃. With the experimental data, the activation energy was obtained through the Arrhenius model, and then the accelerated aging time at the temperature of 80 ℃ equivalent to 6000 h aging at temperature of 25 ℃ was calculated. Secondly, the correlated color temperature (CCT) and color shift during accelerated aging test at the temperature of 80 ℃ were measured by both online test and offline test. It was shown that the increment amounts of CCT and color shift given by the online test were both about 20% higher than that given by the offline test. The t test and t’ test were used to verify the difference in chromaticity, which shows that the difference is of statistical significance. Therefore, the change of CCT and color shift given by the online test during accelerated aging can be used to judge the failure of lamps with some revision of the current criterions.

Optical pumped magnetometer (OPM) aiming at the measurement of Earth’s magnetic field, is firstly optimized by optical simulation, as to maximize the efficient pumping light. Then Mz-magnetometer and Mx-magnetometer are respectively realized in this work, and the correspondent signals are analyzed. The temperature of rf-discharge lamp, the temperature of vapor cell and the amplitude of radio frequency field (RF) are optimized. In Mz mode, the FWHM/SNR of the absorption curve of magnetic resonance (Mz signal) gives 1.3 Hz under 10, 000 nT, with a correspondent field resolution 29.6 pT. Additionally, the scanning rate of RF should be set to be lower than 40 kHz/s, as to obtain a well Lorentzian form of Mz signal. In Mx mode, the free induction decay (FID) signal and Rabi signal are obtained and analyzed. By sweeping the frequency of RF, a so-called “peak splitting” of Mx signal is found to be in existence at the magnetic resonance point theoretically and experimentally, and thereby a suitable amplitude of RF needs to be carefully determined for achieving a satisfied amplitude of Mx signal, as well as for a better sensitivity of magnetometer.

Vanadium oxide (VOx) thin films were deposited on fused quartz using a pure metal vanadium target by RF reactive magnetron sputtering technique. Film microstructure, valence state, optical transmittance properties were studied. The mixed valence VOx thin films deposited with different thickness were found to be amorphous. And the optical transmittance curves are flatness in certain wavelength region. These films can be used to control the relative light intensity of the rubidium light beam between the rubidium lamp and the vapor cell, in order to optimize the working parameters of the rubidium frequency standard (RAFS).