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Research on the signal of 4He pump magnetometer sensor using ECDL laser

One of the most important factors determines specifications of 4He optically pumped magnetometer is the quality of resonance signal given by sensor probe. This paper introduces a laser 4He optically pumped magnetometer using an ECDL laser. An external cavity length tuning system of ECDL laser based on the double light path atom saturated absorption spectrum method with a 4He cell is build up to ensure that an effective 1083.207 nm laser light source is provided for the magnetometer probe. It is designed a double path photoelectric detector to get the absorption peak signal by the difference technology. Because signal in accordance with Lorentz linear features, a detection method combined with first and second derivative of signal curve is proposed. Join a modulation signal whose form is dc component add sinusoidal component, the system make ECDL laser give a stable output wavelength around 1083.207 nm. With the laser light, a resonance signal with better quality than the 4He optically pumped magnetometer probe using the gas discharge lamp light source is given.

Author(s): Wang Chao, Zhou Zhijian, Cheng Defu