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Fourier ptychographic microscopy (FPM) is a newly developed super-resolution technique, which employs angularly varying illumination and a phase retrieval algorithm to surpass the diffraction limit of the objective lens. Specifically, FP captures a set of low-resolution (LR) images, under angularly varying illuminations, and stitches them together in the Fourier domain. However, because the requisite large number of incident illumination angles, the long capturing process becomes an obvious limiting factor. Furthermore, in order to acquire high-dynamic range images, the time can be increased several times over. In this work, utilizing the Hadamard code principle, we propose a highly efficient method, which applies coded multi-angular illumination for FPM, to shorten the exposure time of each raw image. High acquisition efficiency is achieved by employing an optimal multi-angular illumination scheme by using two set of Hadamard coded multiplexing patterns. Both simulation and experimental results indicate that the proposed multi-angular illumination process could shorten the acquisition time of conventional FPM.

Near-infrared diffuse correlation spectroscopy/tomography (DCS/DCT) has recently emerged as a noninvasive measurement/imaging technology for tissue blood flow. In DCT studies, the high-dense collection of light temporal autocorrelation curves (g2(τ)) via fiber array are critical for image reconstruction of blood flow. Previously, the camera-based fiber array limits the field of view (FOV), precluding its applications on large-size human tissues. The line-shape fiber probe based on lens combination, which is predominantly used in current DCT studies, requires rotated-scanning over the surface of target tissue, substantially prolonging the measurement time and increasing the system instability. In this study, we design a noncontact optical probe for DCT based on collimating micro-lens fiber array, termed as FA-nc-DCT system. For each source/detector fiber, a single optical path was collimated by coupling with one micro-lens in the fiber array that is integrated in a square-shape base. Additionally, an 8×8 optical switch is used to share the hardware laser and detectors without spatial scanning. The FA-nc approach for the precise collection of g2(τ) curves was validated through a speed-varied phantom experiment and the human experiments of cuff occlusion, from which the expected value of the blood flow index (BFI) was obtained. Furthermore, the flow anomaly in the phantom and the ischemic muscle in human were accurately reconstructed from the FA-nc-DCT system, which is combined with the imaging framework based on the Nth-order linear algorithm that we recently created. Those outcomes demonstrated the great potential of FA-nc-DCT technology for fast and robust imaging of various diseases such as human breast cancers.

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