The Movement and Control Realization of NVST Polarization Observation System

The new Vacuum Solar Telescope (NVST) is one of the most important solar observing systems, one of its main scientific goal includes high precision and high temporal resolution measurement of the solar magnetic field. NVST polarization analysis system use a mechanical-scanning based polarization observation mode, and due to the structural characteristics of its optical system, NVST inevitably introduces a time-varying biasing effect during the tracking of the sun. Therefore, for polarization observations, system calibration is required. The whole system consists of a calibration unit, an analysis unit and a detector. A plurality of moving parts involved in the process have complex and precise movement requirements. This paper is aimed at the motion requirements of each optical component during polarization calibration process and polarization observation, provides the control requirements of the calibration unit and the analysis unit, and satisfies the movement requirements of the components in different observation modes. Based on TCP/IP protocol remote control program, integrated with serial communication of the commodity drive controller, the software is developed under.NET architecture with calibration control program as well as corresponding user interface, and reserved OCS interfaces are prepared. System performance tests show that, the system satisfies practical observational requirements, and is now deployed into practical use, which lays the foundation for the subsequent polarization observation.