Abstract The search for exoplanets is a focal topic in astronomy. Since the signal from the detected target is very weak, the imaging system needs to have ultra-low readout noise. Therefore, a low noise charge-coupled diode (CCD) imaging system for exoplanet search (LNCIS)
is proposed. Based on the area array CCD (TH7888A), the circuit and timing drive of LNCIS are designed. Especially, the application of correlation dual sampling (CDS) and asynchronous first-in, first-out (FIFO) memory can effectively suppress the correlation noise of the image signal. Moreover,
this article proposes a fully differential double correlation sampling method, which can achieve better sampling effect and can better eliminate common-mode noise, improve dynamic range, and achieve high-quality image signal output. In addition, an independent counting method for adjusting
the exposure time is proposed, which satisfies the requirements of the long exposure time of the imaging system, so that the CCD can be provided an independent and adjustable exposure time in the photosensitive stage. The LNCIS uses the FPGA (ZYNQ7000) as the core control device to produce
the timing according to the function of the system. Finally, the experimental results show that the real-time image acquisition is achieved under the condition that the CCD readout clock frequency is 20 MHz. It is verified that the circuit and timing drive of the imaging system can meet
the design requirements.
Performance assessment of imaging plates for the JHR transfer Neutron Imaging System