Research on the Coupled Modulation Transfer Function of the Discrete Sampling System with Hexagonal Fiber-Optic Imaging Bundles

Abstract

In this study, we developed a numerical model of the coupled modulation transfer function (coupled-MTF) based on the discrete sampling system from the perspective of optical system imaging quality evaluation for coupled two-dimensional discrete sampling characteristics of the hexagonally aligned fiber-optic imaging bundles and CCD image elements. The results show that when the spatial frequency of the input target signal deviates from the Nyquist frequency by 1%, an increase in the number of fibers leads to a faster convergence of the oscillation of the coupled-MTF, and the coupled-MTF converges to a stable value when the number of fibers reaches 1000 × 1000. The deviation of the spatial frequency of the input target signal from the Nyquist frequency is within 1%, and the oscillatory convergence of the coupled-MTF accelerates with increasing deviation. The coupled-MTF oscillates with the deviation period of the wave peak of the input target signal from the initial position of the fiber center, and the theoretical oscillation spatial period is twice the fiber diameter. This study produces important guidelines for the selection of the number of fibers, input spatial frequency, and initial position deviation of the hexagonally arranged fiber imaging bundles.

Nonuniform Background Correction for Wide-Field Surveillance Camera

“…This nonuniformity is caused by the difference in photosensitive source response, noise level, quantum efficiency, etc. At the same time, if the imaging system uses coupling devices such as a fiber panel or fiber cone lens [18], it will also bring serious nonuniformity to the imaging system. These are all static scene correction algorithms; that is to say, when a camera is manufactured, these nonuniformities are fixed, and these algorithms cannot eliminate the interference of uncertain stray light [19].…”

Fiber bundle optical system: imaging modeling and analysis

“…He et al 13 geometrically modeled the optical coupling system of a two-dimensional (2D) square-arrangement fiber bundle (SFB) and statistically derived the coupling-MTF formula. Based on the fact that HFB has a higher filling factor than SFB, Li et al 14 proposed a numerical model for the 2D HFB discrete sampling optical system coupled with a CCD pixel array. However, the model only applies to the special case in which the rectangle pixel array with a particular aspect ratio of ffiffi ffi 3 p ∶2 needs to be processed.…”

“…geometrically modeled the optical coupling system of a two-dimensional (2D) square-arrangement fiber bundle (SFB) and statistically derived the coupling-MTF formula. Based on the fact that HFB has a higher filling factor than SFB, Li et al 14 . proposed a numerical model for the 2D HFB discrete sampling optical system coupled with a CCD pixel array.…”