| The micro digital cameras have been widely used in medical, security and consumer electronics products currently. With the rapid development of information and processing technology, the cameras with the thinner size are increasingly required. The volume of the camera is affected directly by its imaging principle and structure. The multi-aperture imaging system derived from the compound eye of insects has great potential for miniaturization. In this paper, a multi-aperture ultrathin camera based on a freeform mirolens array was designed, which was combined with the different imaging models of microles array. The imaging quality of the camera can be improved, meanwhile the aperture array can be designed and manufactured more easily. The image reconstruction of multi-aperture camera was achieved, according to the theory and methods of image processing and computer vision. The main work of this paper is as follows:1) With the basis on the imaging principle and structure of the existing multi-aperture ultra-thin camera and advantages of the freeform lens, a new multi-aperture ultra-thin camera based on a planar freeform microlens array was proposed. The partial images of each adjacent pair of channels of camera were braided.2) According to structural features of the proposed multi-aperture ultra-thin camera, the methods of optical design and simulation analysis were proposed. A typical system was design, whose specifications are that the number of channels is 3×3, the effective focal length is 5mm, the F-number is 2.8, the field of view is 24°×24° and the material of lens is PMMA. After optimization, the MTF of each lens achieves about 0.1 at 156lp/mm.3) Non-sequential ray tracing was carried out to verify the imaging performance of the multi-aperture camera. Then the elimination of vignetting, improvement of the imaging contrast, removal of noise and the correction of imaging distortion were completed. According to the sampling model of camera, the whole image was reconstructed. |
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