为了获取高信噪比的图像, 采用紫外敏感型科学级光电探测器CCD47-20, 设计了可在特定紫外波段对燃料燃烧火焰进行快速曝光成像的紫外成像系统。CCD47-20具有较深的势阱, 可以保证成像系统的信噪比。然而对于此类CCD, 其曝光时间通常在200 ms以上。为了实现对目标的快速曝光, 在分析CCD47-20的性能及工作原理基础上, 设计了基于两次帧转移、一次水平读出的CCD驱动时序方法, 完成了成像系统的设计, 将CCD的曝光时间缩短至10 ms。在实验室对系统进行了辐照测试, 结果表明, 当曝光时间改变时, CCD响应度为线性, 验证了时序及驱动电路设计的正确性。信噪比测试结果表明系统信噪比达到46.8 dB。在外场, 对固体燃料火焰进行了成像, 获取了火焰在特定紫外波段的图像, 捕捉到了剧烈燃烧的火焰形状, 验证了紫外成像系统快速曝光的性能。

To obtain images with high signal-to-noise ratio (SNR), a ultraviolet imaging system is developed based on a scientific grade CCD (CCD47-20) which is sensitive on ultraviolet. The imaging system can quickly image flames of burning solid fuel at particular ultraviolet waveband. CCD47-20 has deeper potential sell, which guarantees SNR of the imaging system. However, the exposure time of these CCD is usually above 200 ms. To realize quick exposure on target, a CCD driven timing sequence with twice-frame-transfer and once-horizontal-readout is designed based on the analysis of performance and working principle of CCD47-20. The design of imaging system is finished, and the exposure time of CCD is reduced to 10 ms. The irradiation test of the system is carried out in the laboratory. The results show that when exposure time changes, the responsivity of CCD is linear, which verifies the correctness of design of timing sequence and driven circuit. SNR test results show that the SNR of the system can reach 46.8 dB. Flames of burning fuel in the specified ultraviolet waveband are imaged using the ultraviolet imaging system. Shapes of flames are captured, which validates the fast exposure performance of ultraviolet imaging system.