Data-driven polarimetric imaging: a review

This study reviews the recent advances in data-driven polarimetric imaging technologies based on a wide range of practical applications.The widespread international research and activity in polarimetric imaging techniques demonstrate their broad applications and interest.Polarization information is increasingly incorporated into convolutional neural networks(CNN)as a supplemental feature of objects to improve performance in computer vision task applications.Polarimetric imaging and deep learning can extract abundant information to address various challenges.Therefore,this article briefly reviews recent developments in data-driven polarimetric imaging,including polarimetric descattering,3D imaging,reflection removal,target detection,and biomedical imaging.Furthermore,we synthetically analyze the input,datasets,and loss functions and list the existing datasets and loss functions with an evaluation of their advantages and disadvantages.We also highlight the significance of data-driven polarimetric imaging in future research and development.

Lensless polarimetric coded ptychography for high-resolution,high-throughput gigapixel birefringence imaging on a chip

Polarimetric imaging provides valuable insights into the polarization state of light interacting with a sample.It can infer crucial birefringence properties of specimens without using labels,thereby facilitating the diagnosis of diseases such as cancer and osteoarthritis.In this study,we present a novel polarimetric coded ptychography(pol-CP)approach that enables high-resolution,high-throughput gigapixel birefringence imaging on a chip.Our platform deviates from traditional lens-based systems by employing an integrated polarimetric coded sensor for lensless coherent diffraction imaging.Utilizing Jones calculus,we quantitatively determine the birefringence retardance and orientation information of biospecimens from the recovered images.Our portable pol-CP prototype can resolve the 435 nm linewidth on the resolution target,and the imaging field of view for a single acquisition is limited only by the detector size of 41 mm2.The prototype allows for the acquisition of gigapixel birefringence images with a 180 mm^(2) field of view in~3.5 min,a performance that rivals high-end whole slide scanner but at a small fraction of the cost.To demonstrate its biomedical applications,we perform high-throughput imaging of malaria-infected blood smears,locating parasites using birefringence contrast.We also generate birefringence maps of label-free thyroid smears to identify thyroid follicles.Notably,the recovered birefringence maps emphasize the same regions as autofluorescence images,underscoring the potential for rapid on-site evaluation of label-free biopsies.Our approach provides a turnkey and portable solution for lensless polarimetric analysis on a chip,with promising applications in disease diagnosis,crystal screening,and label-free chemical imaging,particularly in resource-constrained environments.

Lensless imaging through thin scattering layers under broadband illumination

Lensless scattering imaging is a prospective approach to microscopy in which a high-resolution image of an object is reconstructed from one or more measured speckle patterns, thus providing a solution in situations where the use of imaging optics is not possible. However, current lensless scattering imaging methods are typically limited by the need for a light source with a narrowband spectrum. Here, we propose two general approaches that enable single-shot lensless scattering imaging under broadband illumination in both noninvasive [without point spread function(PSF) calibration] and invasive(with PSF calibration) modes. The first noninvasive approach is based on a numerical refinement of the broadband pattern in the cepstrum incorporated with a modified phase retrieval strategy. The latter invasive approach is correlation inspired and generalized within a computational optimization framework. Both approaches are experimentally verified using visible radiation with a full-width-at-half-maximum bandwidth as wide as 280 nm(Δλ∕λ = 44.8%) and a speckle contrast ratio as low as 0.0823. Because of its generality and ease of implementation, we expect this method to find widespread applications in ultrafast science,passive sensing, and biomedical applications.