Optical response of a single spherical particle in a laser sheet with application to the Dust Detection System onboard Tianwen-2.

To calibrate the measurement range and accuracy of the Dust Detection System (DDS) onboard the mission, which was developed for the detection of dust particles in the vicinity of the active asteroid 311P/PanSTARRS, the optical response of a spherical particle traversing an elliptical Gaussian beam is analyzed theoretically in the framework of generalized Lorenz-Mie theory, and ground calibration experiments are carried out using spherical particles of different compositions. When a calibration factor for the DDS obtained via measurement is applied, the experimental results are in satisfactory agreement with the theoretical calculations. To facilitate the measurement of the particle diameter, a polynomial relationship between the particle diameters and the detected scattered signals is constructed using a polynomial fitting method. The measured diameter deviation using the predictive model is less than 13%. Ground calibration experiments in a clean room confirm that the DDS has the capability to detect particles with diameters less than 5 µm. Smaller dust particles are expected to be detected in space environments due to the exclusion of scattering from the atmosphere by virtue of the vacuum condition in outer space.