Exquisite High-resolution CCD Camera Design for Parallel-beam Optical-CT Apparatus

Autor: Chao-Nan Hung, 洪超男
Druh dokumentu: 學位論文 ; thesis
Popis: 103
With the technology progress, the performance of the high-resolution camera has been beyond full high-definition (Full-HD, 1920 × 1080) specifications. Among them, the AFE (the analog front end) circuit is the major factor to determine the image quality of the high-resolution camera. Therefore, this study applies ON Semi CCD image sensor to design an analog front end (AFE, Analog Front End) module, which can support 4 type resolutions, 1M (1 million pixels), 2M, 4M, or 8M, respectively. Compared with the original public board (OPB) performance, the original PCB size is 113 mm × 101 mm of AFE module and our design is 48 mm × 48 mm, whose size can be consistent with part of the CMOS design. SNR of our design is higher 9.6% than that of the OPB. Moreover, we employ the resolution of 2336 × 1752 image sensor to measure the amount of space the system resolution. By analyzing the results of Imatest in horizontal and vertical MTF50 performance, compared with 1463 LW/PH (Line Width / Picture Height) and 949 LW / PH of OPB, our design is about 1680 LW/PH and 1396 LW / PH. Therefore, the above results prove that the AFE module of our design can be used as a reliable AFE processing unit. The OCT (Optical Computed Tomography) in order to obtain the precise dose distribution relies on high accuracy (low noise) and high spatial resolution of the image capture system. Therefore, this study proposes a high-resolution CCD-based camera systems design. Part of the low noise, we propose a variety of CCD signal processing to eliminate noise, such as bias clamp, random noise and pixel response non-uniformity. According to the experiment results, our CCD signal processing algorithm can guarantee low noise output. At exposure time of 150 ms, the coefficient of variation of the pixel is reduced from 12.37% to 0.51% by flat-field correction, In the same measurement standards, our system SNR (30.12 dB) better than other brand CCD camera (25.31 dB) and other brand CMOS camera (29.53 dB). Part of the high spatial resolution, we propose high-performance camera design (optical lens, image sensor, image processing) to ensure high spatial resolution output. In MTF50 (Modulation Transfer Function 50%), our camera (1024 × 1024) get the 745 LW/PH (Line Width/Picture Height), close to 73% of the limited resolution; another brand CCD camera (1024 × 768) of 358 LW / PH, about 46.6% of the limited resolution; another brand CMOS camera (3648 × 2736) of 1628 LW / PH, about 59.5% of the limited resolution. Therefore, our camera with a high precision and high spatial resolution design, it can to meet in OCT and increase accuracy of the dose distribution.
Databáze: Networked Digital Library of Theses & Dissertations
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