Knyrim K, Seidlitz H K, Hagenmüller F, Classen M
Endoscopy. 1987 Jul;19(4):156-9. doi: 10.1055/s-2007-1018268.
The subject of this study was the optical performance of video-endoscopic systems (VE) in terms of maximal resolving power and resolvable picture elements. Olympus, Toshiba/Machida, Fujinon, and Welch Allyn video gastroscopes were tested. A GIF Q 10 fiberscope from Olympus was also included for comparison. The resolution measurements were made at various distances using two independent methods--electronic analysis of the TV signal, and visual evaluation of the resolution, of a standardized test target. The results obtained with the two methods were in perfect agreement. The resolution of fine details clearly depends on the distance between the distal end and the target because of decreasing image scale. Depending on the individual optical design, the various VE's show maxima at different distances. At shorter distances, the image is degraded by defocusing. An optimal distance which is as small as possible is desired for clinical routine. Apart from the fiberscope this requirement is best met by the Fuji system. The greatest resolution is obtained with the Toshiba system but at the cost of the viewing angle which is the smallest of all the systems. Fuji combines relatively high resolution with a large viewing angle. Because of the widely varying viewing angle a comparison based solely on resolution cannot represent the true imaging capability of the system. We therefore eliminated purely optical parameters and calculated the number of resolvable picture elements per line. We regard this number to be a fair characterization of both TV and fiber systems.
本研究的主题是视频内窥镜系统（VE）在最大分辨力和可分辨像素方面的光学性能。对奥林巴斯、东芝/町田、富士能和伟伦视频胃镜进行了测试。还纳入了一台奥林巴斯GIF Q 10纤维内镜用于比较。使用两种独立方法在不同距离进行分辨率测量——对电视信号进行电子分析，以及对标准化测试靶标的分辨率进行视觉评估。两种方法得到的结果完全一致。由于图像比例减小，精细细节的分辨率显然取决于远端与靶标的距离。根据各自的光学设计，不同的视频内窥镜系统在不同距离处显示出最大值。在较短距离时，图像会因散焦而质量下降。临床常规操作需要一个尽可能小的最佳距离。除了纤维内镜外，富士系统最能满足这一要求。东芝系统获得的分辨率最高，但代价是其视角是所有系统中最小的。富士系统将相对较高的分辨率与较大的视角结合在一起。由于视角差异很大，仅基于分辨率的比较并不能代表系统的真实成像能力。因此，我们剔除了纯光学参数，计算了每行可分辨像素的数量。我们认为这个数字能公平地表征电视和纤维系统。
