Real Time Polarization Detection of Solar Atmosphere Based on Double DKDP Crystals Principle

Magnetic field is the fundamental driving force of solar eruptions. High precision real-time polarization measurement is a common method to realize magnetic field measurement. However, the commonly used wave plate measurement method needs to be measured many times, and there is a mechanical rotation structure, which can easily cause instrument jitter and reduce the measurement accuracy; the rotation or switching of wave plate also leads to a longer measurement time. At present, the measurement period of solar atmospheric polarization based on DKDP crystal and wave plate is long, and the real-time performance is too low to be applied to the detection of rapidly changing solar active magnetic field. Based on the above background, this paper proposes a real-time polarization detection technology of the solar atmosphere based on the principle of double DKDP crystals. Two DKDP crystals with different fast axis directions are used to realize the polarization modulation of the incident sunlight and obtain the polarization Stokes vector of the solar atmosphere. Compared with the traditional method of combining rotating wave plate and DKDP crystal, the proposed method can increase the single polarization modulation rate from several seconds to millisecond, which greatly improves the real-time performance of solar magnetic field measurement. The simulation results show that the measurement accuracy of the proposed method is 2×10^-3, and the measurement time resolution of single wavelength point is improved by more than 20 times, which can realize the real-time accurate measurement of the polarization information of solar magnetic field.