Typical LED array microscopes require multiple image acquisitions for phase retrieval. Here, we propose a polarized LED array microscope for single-shot quantitative phase imaging with aberration correction. We implemented polarization-encoded illumination multiplexing by placing a custom-made polarization filter on top of the LED array. A single image was captured using a polarized sensor under polarized LED illumination. We reconstructed the quantitative phase by incorporating the polarization multiplexing model with a phase retrieval algorithm. We showed that the proposed technique can reconstruct aberration-corrected phase images with a single-shot intensity image.
We present a novel polarization-sensitive Fourier Ptychographic Microscopy (FPM) method that leverages multiplexing techniques in the Fourier plane, eliminating the need for costly polarization cameras or mechanical polarizer rotations. By simply introducing semicircular 0° and 90° linear polarizers in the Fourier plane of a conventional FPM setup, we can effectively split a single pupil into two half-circle pupils, enabling the simultaneous multiplexing of two channels' signals within a single measurement. By imposing two pupil functions on FP phase retrieval, we reconstructed the amplitude and phase information of the two orthogonal polarization channels, ultimately obtaining the Jones matrix of the anisotropic specimen. To validate our proposed method, we demonstrate its application by accurately reconstructing the orientation of the slow axis and phase retardation of MSU crystals known as the birefringence object.
We report on the design and construction of a goggle-type eye tracker using a low-cost and high-speed lensless camera for monitoring eye movements in neurodegenerative diseases. A Rolling Shutter image sensor combined with lensless computational imaging allows for the reconstruction of a time sequence of images from a single snapshot, effectively improving the framerate of the camera. We constructed and demonstrated the prototype device using a commercial-grade CMOS image sensor and achieved the improvement of framerate from 15 to 480Hz, with the tracking results for 28 clinical measured data. Our device can potentially measure microsaccadic eye movements in a wearable camera format, allowing routine monitoring of abnormal eye movements for the early diagnosis and tracking of Alzheimer’s and Parkinson’s disease.
Fourier ptychography (FP) utilizes angle-varied illumination to achieve resolution improvement and quantitative phase imaging. In this talk, we present a compact microscope using an OLED screen as a programmable illumination for FP reconstruction. We discuss multiplexed reconstruction strategy using multi-pixel illuminations, and a stand-alone smartphone implementation of portable FPM.
Fourier Ptychographic Microscopy (FPM) is a computational imaging technique which reconstructs super-resolved amplitude and phase images by combining variably illuminated low-resolution images through an iterative phase retrieval algorithm. However, the phase-retrieval-based reconstruction requires sufficient overlap between spatial frequency bands of the measurements, which creates a trade-off between the number of measurements and the reconstruction quality. We propose a deep-learning-based FPM reconstruction that recovers both amplitude and phase images in high resolution with far fewer measurements than conventional FPM, with model-based constraint. Our model works with almost no overlap between low-resolution measurements in the Fourier domain, only taking into account the total Fourier extent of the measurements.
We propose a simple smartphone attachment module to realize a portable wide-field high-resolution microscope based on Fourier Ptychographic Microscopy (FPM). Using the smartphone's screen as the illumination and the front camera module for image acquisition, we can construct a stand-alone portable FPM, a microscopy technique that can achieve high resolution by computationally combining a number of variably illuminated low-resolution bright-field and dark-field images through an iterative phase retrieval algorithm. With the custom-built android application that performs in situ calculation for acquisition, reconstruction, and display of the images, we can achieve a true stand-alone portable imaging device for field applications.
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