In an effort to increase camera readout speed, we have developed a nonconventional vidicon tube scanning technique. Because all vidicon targets are round, acquiring a full view requires overscanning with a conventional square format scan, resulting in 22% of the video field time wasted. Furthermore, conventional scanning employs horizontal flyback, which for high frame rates can be more than 10% of the total field time. Our nonconventional scanning technique eliminates flyback time by utilizing a triangular waveform rather than a sawtooth for horizontal deflection. This triangle wave is amplitude modulated in order to scan only the (circular) area of interest. The vertical deflection is a staircase ramp, with a step occurring at the end of each horizontal line. This maintains even spacing and a parallel relationship between horizontal lines, as opposed to skewed lines with conventional scans. To display the video output, the X-Y monitor must also be driven with these waveforms in order to maintain the correct temporal and spatial position of the video data. Sweep rates of 400 lines in a 1 ms field have been demonstrated. Test results using this technique show a frame time reduction of approximately 30%, with no loss of resolution or dynamic range, and no increased video bandwidth requirements.

Date Published: 1 January 1992
PDF: 5 pages
Proc. SPIE 1539, Ultrahigh- and High-Speed Photography, Videography, and Photonics '91, (1 January 1992); doi: 10.1117/12.50546

Published in SPIE Proceedings Vol. 1539:
Ultrahigh- and High-Speed Photography, Videography, and Photonics '91
Paul A. Jaanimagi, Editor(s)