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Significance: Large space-bandwidth product is highly desirable in many biomedical imaging. Fourier ptychographic microscopy (FPM) is a computational imaging technique that can significantly increase the space-bandwidth product of a standard microscope. The illuminator of a Fourier ptychographic microscope is not flexible at present, and it is inconvenient to meet different imaging needs., Aim: An illuminator based on a two-axis motorized rotation stage was presented to provide a more flexible illuminating way with the goal of meeting different imaging needs., Approach: The illuminator adopts a concentric illuminating method to provide coherent illumination in any direction on the sample plane. The sampling pattern can be freely designed and changed according to the parameters of the imaging system. A dither removing algorithm was proposed to remove the potential dither influence introduced in the image acquisition process., Results: The illuminator could be conveniently integrated into different imaging systems. The feasibility and flexibility were demonstrated by applying it to imaging systems with numerical aperture of 0.045 and 0.01. The resolution gain is about 4- and 13-fold, respectively. The effectiveness of the dither removing algorithm was validated in both simulation and experiment., Conclusions: A more flexible illuminator for FPM was presented to meet different imaging needs. A dither removing algorithm was proposed to remove dither influence.

Traditional Fourier ptychographic microscopy (FPM) requires the acquisition of multiple images, which limits the acquisition speed and increases storage requirements. Here, we present a compressed sampling method for FPM (CSFPM), wherein we randomly switch on a certain number of the source LEDs each time to collect compressed data and use it to recover an FPM low-resolution image set. Subsequently, we utilize a general FPM recovery algorithm to reconstruct a high-resolution image. We conduct simulations and experiments to validate the CSFPM feasibility and acquisition efficiency. Our results demonstrate that CSFPM reduces the acquisition-data amount by 49.59% and acquisition-time by 84.63% relative to traditional FPM. • Applying compressed sensing to FPM. • Decreasing the acquisition data and time in FPM. • Increasing the sensitivity of FPM to high frequency data. [ABSTRACT FROM AUTHOR]

Fourier ptychographic microscopy has recently attracted attention because of its ability to expand the space–bandwidth products of an imaging system. To improve the efficiency of information acquisition, large numerical apertures and low-overlapping rates should be employed. However, the pixel aliasing problem occurs in phase recovery in the under-sampling condition. An algorithm was developed to solve the pixel aliasing problem with low overlapping requirements. Combined with total variational optimization procedures, the overlapping requirements were reduced, and the noise was suppressed. Compared with the upsampled method, the proposed algorithm achieved evident overlapping rate reduction. With a spatial-sampling ratio of 0.72, satisfactory effects were achieved at the minimum overlapping rate of 24% in simulation, which meant a significant reduction in the amount of data. A limitation for the objective lens aperture was identified, and a theoretical explanation is proposed. • An algorithm to solve the pixel aliasing problem with low overlapping requirements for FPM. • Overlapping requirements were reduced, and the noise was suppressed. • Excellent results with spatial-sampling ratio of 0.72 and overlapping rate of 24%. [ABSTRACT FROM AUTHOR]