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Imaging of the fiber whole-mount. The cross-polarized images are shown in the second column and colored in neon blue.
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Lensless imaging has recently become an alternative and cost-effective choice for many macro and micro applications, like wave-front sensing, fluorescence imaging, holographic microscopy, and so on. However, the polarized imaging, especially the cross-polarized light, has rarely been explored and integrated in lensless imaging methods. In this pape...
Citations
... Another alternative to conventional lens-based polarization light microscopy is to perform polarimetric imaging without using any lenses [27][28][29][30][31][32] . For example, multi-height phase retrieval has been implemented with a polarizer-analyser pair for lensless polarimetric imaging, demonstrating great potential for biomedical applications 28 . ...
Polarimetric imaging provides valuable insights into the polarization state of light interacting with a sample. It can infer crucial birefringence properties of bio-specimens without using any labels, thereby facilitating the diagnosis of diseases such as cancer and osteoarthritis. In this study, we introduce a novel polarimetric coded ptychography (pol-CP) approach that enables high-resolution, high-throughput birefringence imaging on a chip. Our platform deviates from traditional lens-based polarization systems by employing an integrated polarimetric coded sensor for lensless diffraction data acquisition. Utilizing Jones calculus, we quantitatively determine the birefringence retardance and orientation information of bio-specimens from four recovered intensity 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 mm^2. The prototype allows for the acquisition of gigapixel birefringence images with a 180-mm^2 field of view in ~3.5 minutes, achieving an imaging throughput comparable to that of a conventional whole slide scanner. 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, indicating the potential for rapid on-site evaluation of label-free biopsies. The reported approach offers a portable, turnkey solution for high-resolution, high-throughput polarimetric analysis without using lenses, with potential applications in disease diagnosis, sample screening, and label-free chemical imaging.
... In addition, PLM, as in conventional microscopes, has limited SBP. In order to circumvent these limitations, birefringence imaging has recently been demonstrated on various imaging platforms, such as digital holographic microscopy [29], ptychography [30], single-pixel imaging [31], differential phase-contrast microscopy [32], and lens-less holographic microscopy [33,34]. Among them, lens-free holographic polarization microscopy enables large-area birefringence imaging in a lens-free manner, but two sets of raw holograms must be taken with illuminations in two different polarization states, which requires precise image alignment. ...
Birefringence, an inherent characteristic of optically anisotropic materials, is widely utilized in various imaging applications ranging from material characterizations to clinical diagnosis. Polarized light microscopy enables high-resolution, high-contrast imaging of optically anisotropic specimens, but it is associated with mechanical rotations of polarizer/analyzer and relatively complex optical designs. Here, we present a novel form of polarization-sensitive microscopy capable of birefringence imaging of transparent objects without an optical lens and any moving parts. Our method exploits an optical mask-modulated polarization image sensor and single-input-state LED illumination design to obtain complex and birefringence images of the object via ptychographic phase retrieval. Using a camera with a pixel resolution of 3.45 um, the method achieves birefringence imaging with a half-pitch resolution of 2.46 um over a 59.74 mm^2 field-of-view, which corresponds to a space-bandwidth product of 9.9 megapixels. We demonstrate the high-resolution, large-area birefringence imaging capability of our method by presenting the birefringence images of various anisotropic objects, including a birefringent resolution target, liquid crystal polymer depolarizer, monosodium urate crystal, and excised mouse eye and heart tissues.
... In this system, we utilize a laser as coherent light source and convert it to parallel light by a collimator. Inspired by [28], we also insert two polarizers in the front and rear of the sample to fix the wavelength and polarization state of the light source to obtain stable modulation. The light of the object diffracts from the object plane to SLM plane after propagating 1 distance. ...
Lensless imaging is a popular research field for the advantages of small size, wide field-of-view and low aberration in recent years. However, some traditional lensless imaging methods suffer from slow convergence, mechanical errors and conjugate solution interference, which limit its further application and development. In this work, we proposed a lensless imaging method based on spatial light modulator (SLM) with unknown modulation curve. In our imaging system, we use SLM to modulate the wavefront of object, and introduce the ptychographic scanning algorithm that is able to recover the complex amplitude information even the SLM modulation curve is inaccurate or unknown. In addition, we also design a split-beam interference experiment to calibrate the modulation curve of SLM, and using the calibrated modulation function as the initial value of the expended ptychography iterative engine (ePIE) algorithm can improve the convergence speed. We further analyze the effect of modulation function, algorithm parameters and the characteristics of the coherent light source on the quality of reconstructed image. The simulated and real experiments show that the proposed method is superior to traditional mechanical scanning methods in terms of recovering speed and accuracy, with the recovering resolution up to 14 um.
... Integrated polarized radiative semiconductor light-emitting sources can significantly reduce system complexity and enable innovative applied designs, and have attracted substantial interest from academia and industry, for applications such as quantum information coding [1,2], advanced imaging and sensing [3][4][5], and displays [6,7]. To realize highly integrated light-emitting sources, the primary approaches include two categories, materials technology and subwavelength structure modulation. ...
Polarized radiative semiconductor luminous chips have huge application potentials in lots of high value-added fields. Integrating a subwavelength grating is recognized as the most promising method for development of polarized chips, but still faces the challenge of lower polarized radiation performance. The paper proposed and developed a scattering-induced polarization enhancement light emitting diodes chips by directly nanoimprinting metal-containing nanoparticles-doping-grating on the top surface of a common flip-chips. The utilization rate of quantum well light emission on the developed polarized chips was improved more than 30%. More attractively, the doped scattering nanoparticles play as a scattering-induced polarization state converter that sandwiched in the top aluminum grating and bottom silver reflector on the chips. The originally non-radiative light with an electric field vector parallel to the grating lines is reflected back and forth among the sandwich until it changes to the perpendicular vibration mode to radiate outside the chips. Therefore, the polarization extinction ratio was greatly improved compared with the samples without doping.
Birefringence, an inherent characteristic of optically anisotropic materials, is widely utilized in various imaging applications ranging from material characterizations to clinical diagnosis. Polarized light microscopy enables high-resolution, high-contrast imaging of optically anisotropic specimens, but it is associated with mechanical rotations of polarizer/analyzer and relatively complex optical designs. Here, we present a form of lens-less polarization-sensitive microscopy capable of complex and birefringence imaging of transparent objects without an optical lens and any moving parts. Our method exploits an optical mask-modulated polarization image sensor and single-input-state LED illumination design to obtain complex and birefringence images of the object via ptychographic phase retrieval. Using a camera with a pixel size of 3.45 μm, the method achieves birefringence imaging with a half-pitch resolution of 2.46 μm over a 59.74 mm² field-of-view, which corresponds to a space-bandwidth product of 9.9 megapixels. We demonstrate the high-resolution, large-area, phase and birefringence imaging capability of our method by presenting the phase and birefringence images of various anisotropic objects, including a monosodium urate crystal, and excised mouse eye and heart tissues.
With the advantages of a large field of view, portability, and cost-effectiveness, lensless imaging has been applied widely nowadays. However, as a powerful tool for complete polarimetric characterization of microstructural and optical properties of a medium, Mueller matrix imaging has not yet been integrated in lensless imaging scheme. Here we propose a lensless inline polarization holographic system for high-speed and high-resolution Mueller matrix imaging. Liquid crystal variable retarders are introduced to realize high-speed response and avoid vibrations and positioning errors. We apply the blind deconvolution for depolarized imaging reconstruction and the back-propagation approach for polarization hologram reconstruction, respectively. The polarimetric imaging ability and resolution performance of the proposed technique are demonstrated. Furthermore, Mueller matrix images and certain quantitative polarimetric parameters of biological samples are calculated. The proposed method can be easily implemented and integrated in various lensless imaging techniques for on-chip polarimetric imaging.
Optical image sensors are 2D arrays of pixels that integrate semiconductor photodiodes and field effect transistors for efficient photon conversion and processing of generated electrons. With technological advancements and subsequent democratization of these sensors, opportunities for integration with microfluidics devices are currently explored. 2D pixel arrays of such optical image sensors can reach dimensions larger than one centimeter with a sub-micrometer pixel size, for high spatial resolution lensless imaging with large field of view, a feat that cannot be achieved with lens-based optical microscopy. Moreover, with advancements in fabrication processes, the field of microfluidics has evolved to develop microfluidic devices with an overall size below one centimeter and individual components of sub-micrometer size, such that they can now be implemented onto optical image sensors. The convergence of these fields is discussed in this article, where we review fundamental principles, opportunities, challenges, and outlook for integration, with focus on contact-mode imaging configuration. Most recent developments and applications of microfluidic lensless contact-based imaging to the field of biosensors, in particular those related to the potential for point of need applications, are also discussed.
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 mm ×41 mm . The prototype allows for the acquisition of gigapixel birefringence images with a 180 mm ×180 mm 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.
The implementation of a compact and portable digital lensless holographic microscope (P-DLHM) attached to a cellphone is presented. This proposal offers a potential tool for telemedicine applications via the in-situ study of biological samples.
