By iteratively stitching together the series of low-resolution (LR) images captured by either various small-aperture illuminations or angle-varied illuminations, the Fourier ptychography (FP) can recover large space-bandwidth- product (SBP) and high-resolution (HR) object images. The FP has been considered to be promising in various computational imaging fields. However, the illumination-based FP is limited by strict requirements of the objects which must be thin and satisfy the one-to-one mapping relationship in the Fourier plane, and the aperture-scanning Fourier ptychography is also limited by the long-time scanning and stable scanning mechanical structures requirements even though it can achieve super-resolution macroscopic imaging. Furthermore, the position and shape of the scanning aperture must be accurately modeled for the reconstruction, otherwise false object images may be output. Herein, based on the 4-f optical correlator structure, we proposed a novel method, termed variable-aperture Fourier ptychography, for reconstructing HR images from series of LR images. The numerical simulations illustrated that the variable-aperture Fourier ptychography can use a small number of LR images to reconstruct the object images, The experiments demonstrated that a high-quality object image with better resolution and contrast than other schemes, include direct imaging based on 4-f system and aperture scanning FP, can be obtained by our method. Two additional experiments proved that it is almost unaffected by the position and shape of the apertures.
The encoding aperture errors with different types and different degrees occurred during the process of encoding aperture by micro-Nano technology. The encoding aperture is a key component of the CSSI, and the analysis of errors in encoding aperture processing provides an important evidence for the CSSI. In this paper, based on the error occurring in the process of encoding aperture, the simulation is established by commercial software FDTD by which the optical field modulation of incident light in the CSSI system is analyzed by comparing the ideal encoding aperture and the error encoding aperture. The simulation results show that there is a significant difference in the optical intensity distribution of incident light modulated by a single error aperture and a single ideal aperture, the optical intensity distribution modulated by the ideal aperture has two distinct peaks at the aperture surface, and the optical intensity distribution modulated by the error aperture is approximately twice as large as by the ideal aperture; the optical intensity distribution modulated by the two type aperture has obvious peaks while leaving the aperture surface, and the optical intensity distribution modulated by the ideal aperture is approximately twice as large as by the error aperture; changing the number of pixels of the encoding aperture, the ideal encoding aperture and the error encoding aperture have little difference in modulation of the incident light; comparing the ideal aperture, as the increasing of the rounded radius of error aperture, the influence of the optical field distribution modulation becomes more obvious.
Under coherent light illumination, several approaches need either angle scanning or diffuser rotating to reconstruct the image through opaque scattering media. We propose a linear model to restore the hidden object through the actual power spectrum with disturbance of the scattering layer. The experimental results confirm that, the algorithm quickly converge to the only correct reconstruction solution with the accuracy power spectrum pattern of Fourier transform, and the method can reconstruct the high accuracy image of the object hidden by the scattering media with one-shot power spectrum.
This article depicts a experiment of utilizing multi-spectral image(MSI) system, which can benefit from compressed sensing to reduce data acquisition demands, with the employment of a dispersal prism and push-broom compressive sampling system, to realize image super-resolution both in spatial and in spectral.