Design and implementation of CCD imaging system for directional polarimetric camera

A CCD imaging system in the Directional Polarimetric Camera is developed, which is comprised of timing driving unit, pro-processing and analog-front-end unit, FPGA main control unit, internal communication and remote measurement unit, image transmission interface unit, and so on. A CCD driving timing method with twice frame transfer and once horizontal readout is proposed to effectively eliminate the residual charge of last frame image and improve the signal-to-noise ratio. The performance of this CCD imaging system is verified. The experimental results show that the 14bit image data can output steadily with a frame frequency of 2.02 frames per second. The imaging signal-to-noise ratio can reach 54.93dB when the CCD is lower than saturated. The dynamic range of the CCD detectable signals is 68.98 dB and the nonlinearity error under different wavelengths is less than 1%. The instrumentation can satisfy the operational requirements such as stable output, excellent linear performance, high signal-to-noise ratio and large dynamic range.