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In recent years, optical fiber image transmission bundle has the advantages of light weight, fine diameter, good flexibility, strong electromagnetic interference resistance, good radiation resistance and so on. It is a kind of passive device that can be bent. Therefore, it is impossible to use optical fiber image transmission bundle to be replaced by traditional optical system [1, 2]. At present, optical fiber image bundle has been widely used in medical endoscope and military and industrial detection system, has a very wide application prospect, so the development of optical fiber image bundle has aroused great attention in various countries . As the key component of image transmission, optical fiber image transmission bundle must have high resolution and good image transmission quality. Resolution is a kind of detail resolution ability of optical fiber image transmission elements. The higher the resolution, the stronger the ability of resolving image details. Theoretically, the smaller the diameter of the image transmission unit of the fiber bundle is, the higher its resolution will be. However, in practice, when the image transmission unit cannot independently transmit the image, its resolution will disappear. At present, there are two kinds of high resolution optical fiber image bundles: hard optical fiber image bundles by arrangement method and flexible optical fiber image bundles by acid solution method[3].Due to the particularity of acid solution method, the image of flexible fiber image transmission bundle has regular mesh defects, which requires post-processing and distortion. The resolution of the hard bundle is not only related to the arrangement of the single pixel, but also to the effect of the size of the single pixel on the light wave transmission. In this paper, high transmittance and large numerical aperture glass fibers are fabricated by high transmittance and low refractive index leather glass and high transmittance and high refractive index core glass. The research is carried out through the combination of phenomenon analysis, theoretical simulation and experimental verification, and the influence of single pixel with different size parameters on light conduction is studied by simulation calculation. In this paper, the standard resolution card test is used to compare the images at the output end of different samples, and the maximum spatial frequency of visual resolution on the target image is taken as the limit resolution of the tested fiber bundle sample, and the resolution value can be obtained. Based on the analysis of experimental results and theoretical simulation results, the structural parameters of the high resolution optical fiber image bundle are designed and optimized.
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