Panoramic annular lens (PAL) system consists of a panoramic head block unit and a relay lens system, adopting a plane cylindrical projection method to project a cylindrical field of view around the optical axis 360° into a two-dimensional planar annular region to realize super hemispherical imaging. PAL system requires large field of view imaging on a limited image plane, which inevitably results in lower image resolution and poor local detail imaging. However, the information processing speed gets faster with the development of 5G, which leads to a growing demand for better image quality and clarity. This paper presents a PAL system matching image sensors with 4K resolution, which can demonstrate the details about the object and get a smooth and ultra-high definition image. Unlike other sensors, it has large image faces and tiny pixels and the effective number of the pixel is about 24.3 million (4K × 6K). The proposed PAL system has 6 sets of 9 lenses with compact structure. The F-theta distortion of the full field of view is less than 1%, and the modulation transfer function value of each field of view is greater than 0.5 at the Nyquist spatial frequency of 130lp/mm which approaches diffraction limitation. The designed system has good imaging quality and meets the application requirements.
A traditional tracking device obtain the attitude angle by analyzing the spots position on photodetector. However, the attainable angular measurement accuracy depends on the field of view (FOV), number of pixels of the photodetector and the centroiding algorithm. In this paper, we present a high-precision attitude angle measuring system based on Talbot interferometry using cross-gratings and four wedge plates, which can acquire the real-time change of incident angle along two axis. The specific structure of the system is introduced, and the formula for calculating the relative angle is derived. The tracking accuracy is analyzed to be better than 0.2 arcsecond, which is dependent on the grating period, the distance between the two gratings and the gray scale of image. The Simulation results show that the RMS error of relative angle is better than 0.1 arcsecond both in x and y direction.
Panoramic annular lens (PAL) is a kind of the specific wide angle lenses which is widely applied in panoramic imaging especially in aerospace field. As we known, to improve the aerodynamic performance of the aircraft, conformal dome, which notably reduces the drag of an aircraft, is also functioning as an optical window for the inbuilt optical system. However, there is still no report of the specific analysis of the imaging performance of PAL with conformal dome, which is imperative in its aerospace-related applications. In this paper, we propose an analysis of the imaging performance of a certain PAL with various conic conformal domes. Working in visible wavelength, the PAL in our work observes 360° surroundings with a large field of view (FOV) ranging from 30° ~105° . Meanwhile, various thicknesses, half-vertex angles, materials of the conic dome and the central distances between the dome and PAL are considered. The imaging performances, mainly indicated by modulation transfer function (MTF) as well as RMS radius of the spot diagram, are systematically compared. It is proved that, on the contrary to the general cases, the dome partly contributes to the imaging performance of the inbuilt PAL. In particular, with a conic conformal dome in material of K9 glass with a half-vertex angle of 25° and a thickness of 6mm, the maximum MTF at 100lp/mm could be improved by 6.68% with nearly no degeneration of the minimum MTF, and the RMS radius could be improved by 14.76% to 19.46% in different FOV. It is worth to note that the PAL is adaptive to panoramic aerospace applications with conic or quasi-conic conformal dome and the co-design of both PAL and the dome is very important.
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