Publications by authors named "Sifeng He"

Ultra-high-speed imaging serves as a foundation for modern science. While in biomedicine, optical-fiber-based endoscopy is often required for in vivo applications, the combination of high speed with the fiber endoscopy, which is vital for exploring transient biomedical phenomena, still confronts some challenges. We propose all-fiber imaging at high speeds, which is achieved based on the transformation of two-dimensional spatial information into one-dimensional temporal pulsed streams by leveraging high intermodal dispersion in a multimode fiber.

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This paper presents an effective approach to alleviate the cat-eye effect by inserting a freeform single lens into the original optical system. By shifting the image of the given optical system transversely on the original image plane, the reflected beams originating from the sensor are subsequently blocked by the optical aperture, substantially eliminating retroreflections from the system. The influence of incident angle on retroreflected beams is analyzed in detail, and the optimal image translation distance for completely eliminating the cat-eye effect is also proposed via numerical simulations.

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The security threats caused by multi-rotor unmanned aircraft vehicles (UAVs) are serious, especially in public places. To detect and control multi-rotor UAVs, knowledge of IR characteristics is necessary. The IR characteristics of a typical commercial quad-rotor UAV are investigated in this paper through thermal imaging with an IR camera.

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In this paper, we propose an applicable propagation model for Gaussian beams passing through any cat-eye target instead of traditional simplification consisting of only a mirror placed at the focal plane of a lens. According to the model, the cat-eye effect of CCD cameras affected by defocus is numerically simulated. An excellent agreement of experiment results with theoretical analysis is obtained.

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