NVST Multi-Channel High-Resolution Imaging System

The New Vacuum Solar Telescope is an 1-meter,ground-based telescope which offers the unparalleled performance to solar observations.One of the important instruments in the NVST is the multi-channel high-resolution imaging system,and in the system five main work wave length ranges,including Hα,TiO-band,G-band,Ca II(854.2nm) and He I(1083.0nm) are covered.Up to now,Hα and TiO-band channels are being used.The Hα channel is an arrow-band imaging system,equipped with a tunable Lyot filter.The interpretation of the narrow-band filtergram is difficult due to the crosstalk between the brightness and the Dopplershift modulation,therefore the observational system is required to perform the multi-offband observation in Hα channel to obtain a scanned profile in order to get meaningful physical information.The TiO-band is abroad-band imaging system and uses a high-cadence CMOS.To achieve much higher cadence for some specific observations,it should support to decrease the FOV to increase the acquisition speed of the camera.However,the software provided by the camera manufacturedis failed to meet the observation need so that a new observational software system is constructed to satisfy the different observational needs in two channels.Taking the factors into account that another three channel will soon be added and high-cadence cameras will come into uses,the software architecture designed for NVST acquisition system should provide the scalability and the flexibility to adapt to changes in technologies throughout the lifetime of NVST.To achieve this goal,the distributed multi-terminal deployment and a loosely coupled system is adopted.The system is based on a tiered software architecture implemented as three primary systems that are the Observation Control System(OCS),the Instrument Control System(ICS) and the Data Handling System(DHS).The OCS interacts with our staff and coordinates the overall observational operations.The ICS manages the instruments and the DHS manages the data operation including saving,processing and transferring.For decoupling the logical systems they can be developed independently so that the software architectures are separated into the functional architecture and the technical architecture,patterned similar to that adopted by the ACS(ALMA Common Service).The technical architecture describes the underlying implementation of the technical aspect,such as threading and message broadcasting.The functional architecture,in contrast to the technical architecture,describes the functional behavior.Therefore the container/component mode is adopted to achieve this separation of architectures.The container manages many components which provide functional behavior.This paper describes the deployment of acquisition system and the design of the software architecture on the top of the container/component mode to achieve the scalability and flexibility to adapt the changes in observational instruments and in observational methods