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Development of high-speed CCD control system for adaptive optics

Kim, Ee-Eul; (1998) Development of high-speed CCD control system for adaptive optics. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

The air turbulence in the Earth's atmosphere causes the wavefront distortion of the incoming light from an object and the degradation of the image quality for a ground- based astronomical telescope. The adaptive optics is the technique that corrects the wavefront distortion and attempts to restore the image to a quality close to the diffraction limit in real-time. The wavefront sensor, one of the fundamental elements in an adaptive optics system, is used to measure the wavefront distortion. The charge- coupled device(CCD) is the detector that is most widely employed for wavefront sensors because of its high quantum efficiency, 100 % fill-factor, and precise pixel positions. This thesis describes the design and construction of a high-speed CCD control system primarily for wavefront sensors. The control system employs a high-speed FPGA(field-programmable gate array) as the sequencer and high-speed CCD clock drivers. It has the versatility to generate streams of clock and control pulses and biases for various different types of high-speed CCDs. It incorporates the modular graphical user-interface that provides a graphical and easy-to-use control environment to the system user. With the host personal computer(PC) and the main power supply unit, the control system is compact, modular, portable, and stand-alone. These features make the control system satisfy the required spatial resolution and temporal sampling frequency for wavefront sensing in different environments. Its versatility and modularity are also instrumental in obtaining the optimum performance of the control system for a specific condition. The results from some primary tests performed on the control system are presented and discussed. With some more tests and optimisation, the control system will be applicable to practical wavefront sensing for ground-based astronomical telescopes. Moreover, with little physical modification, it can be applied to numerous fields of science and engineering.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Development of high-speed CCD control system for adaptive optics
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; CCD control systems
URI: https://discovery.ucl.ac.uk/id/eprint/10097536
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