The in-situ investigation of interstellar dust has becoming one of the focuses in deep space exploration. It is of great importance since it provides us with key information about the origin and evolution of planets. To measure the size of a single slow dust particle, a laser-based optical measurement system was designed and calibrated accordingly. In this system, a detection area of 50mm*50mm laser curtain was generated using a diffractive optical element (DOE) and a cylindrical lens, which transform the laser beam in Gaussian profile to a laser sheet with a rectangular uniform profile. When a dust particle passes through the laser curtain, scattered light will be generated and collected by a compound parabolic concentrator (CPC) and then be converted into an electrical signal by a PIN photodiode. The amplitude of electrical signals, which are directly related to the scattered light flux, are used to extract the particle size. Standard spherical SiO2 sample particles of different sizes were used in the calibration activities. Satisfied agreements have been achieved between the theoretical result calculated using the Lorenz-Mie theory and the experimental result.

A Main Belt Comet exploration mission has been proposed to perform rendezvous with a Main Belt Comet in the future, and the probe will orbit the comet and carry on complete investigation. The scientific objective of the Main Belt Comet Dust Analyzer (MBCDA) instrument, part of the scientific payload onboard the Main Belt Comet mission, is to explore the ejections, orbit activity and origin of the comet, as well as dust evolution in the coma and their influence on the probe. To this aim, MBCDA is composed of different modules: a Microbalance Sensor system, to measure the dust flux from different directions and perform a thermo-gravimetric analysis, a Dust Size Sensor, to monitor the grain's diameter by optical detection, a Dust Momentum Sensor, to detect the momentum carried by the particles, and a Microscopic Imaging System, to obtain the morphological, charging properties and composition information of the comet dust. The preliminary calibration results of MBCDA demonstrate that the instrument is basically compatible with design specifications and is suitable to obtain scientific results about cometary dust.