Modern quantitative optical imaging possesses a huge information capacity. We present an aberration-free high-bandwidth holographic microscopy which exploits high-throughput label-free quantitative phase image. The maximum space bandwidth efficiency in a single multiplexing hologram can be reached at 78.5%. By assisting with the off-axis optimized initial phase in the phase retrieval, high-resolution and full-field reconstruction by exploiting the full bandwidth are demonstrated for complex-amplitude reconstruction. Then, we import variable sparse splitting framework on quantitative phase aberration extraction in holographic microscopy. The aberration-free two-dimensional and three-dimensional imaging experiments are demonstrated.
As the basis of virtual content creation, cameras are integral to augmented reality (AR) applications. However, the opaque nature of the camera's appearance can prevent it from being integrated into a transparent AR display. Here we introduced an integrated, compact, and flexible see-through camera, which enables crucial functionalities like eye gaze tracking and eye-position perspective photography, enhancing the immersive experience and interaction possibilities.
Quantitative phase imaging (QPI) techniques are faced with an inherent trade-off between phase imaging fidelity and temporal resolution. Here, we propose a general algorithmic framework for QPI reconstruction that takes into account the spatiotemporal image priors. In particular, total variation with respect to the complex spatio-temporal datacube is introduced as a sparsity-promoting regularizer. The phase retrieval process is formulated as a standard optimization problem and is solved via an accelerated proximal gradient method. The algorithms are evaluated on a proof-of-concept QPI imaging system based on defocus diversity. Numerical and experimental results both indicate that the proposed spatio-temporal compressive phase retrieval framework could achieve high-fidelity quantitative phase imaging while improving the temporal resolution to that of a single-shot method. We experimentally demonstrate video-rate QPI of dynamic biological activities that is free of motion blur and twin-image artifacts. The proposed framework could potentially achieve a high space-bandwidth-time product and push the information throughput of QPI systems towards the theoretic limit.
Objective measurements of the morphology and dynamics of label-free cells and tissues can be achieved by quantitative phase with low phototoxicity and no photobleaching. Modern quantitative optical imaging possesses a huge information capacity. The morphology and dynamics of label-free tissues can be exploited by sample-induced changes in the optical field from quantitative phase imaging. Its sensitivity to subtle changes in the optical field makes the reconstructed phase susceptible to phase aberrations. We present aberration-free high-bandwidth holographic microscopy which exploits high-throughput label-free quantitative phase imaging. Firstly, a full-bandwidth holographic reconstruction is retrieved from interferograms by establishing a holographic multiplexing framework. Based on the analyticity of band-limited signal under a diffraction-limited system, the maximum space bandwidth utilization limit in a single multiplexing hologram is increased to the maximum sensor limit. Secondly, A variable sparse splitting framework on quantitative phase aberration extraction is imported based on the alternating direction aberration-free method. By formulating the aberration extraction as a convex quadratic problem, the background phase aberration can be fast and directly decomposed with the specific complete basis functions such as Zernike or standard polynomials. Faithful high throughput phase reconstruction can be obtained by eliminating global background aberration. It opens a new route to multiplexing quantitative optical imaging and helps to improve the performance of constraint-free modern optical microscopes in various spectral regimes.
Lab-on-a-Chip microfluidic devices represent an innovative and cost-effective solution in the current trend of miniaturization and simplification of imaging flow cytometry. Cell tracking is a fundamental technique for investigating a variety of biophysical processes, from intracellular dynamics to the characterization of cell motility and migration. The conventional target positioning based on holography is typically addressed by decoupling the calculation of the optical axis position and the transverse coordinates. The 2D positions of each cell are located based on the phase contrast. The axial position of the cell area is calculated by refocused external criterion in complex amplitude wavefront. Computing resources and time consumption may increase because all the frames need to be performed calculations in the spatial frequency domain. We proposed a space-time digital hologram encoding method to speed up 3D holographic particle tracking. The 2D positions of each cell are directly located by morphological calculation based on the hologram. The complex amplitude wavefronts are directly reconstructed by space-time phase shifting to calculate the axial position by refocused external criterion. Only spatial calculation is considered in the proposed method. The proposed approach can be used in microfluidics to analyze objects flowing in microfluidics channels.
Objective measurements of the morphology and dynamics of label-free cells and tissues can be achieved by quantitative phase. Modern quantitative optical imaging possesses a huge information capacity. But the bandwidth of quantitative phase imaging is technically limited in an interferometric setup, thereby constraining the throughput in label-free phase imaging. Firstly, we demonstrate a high-bandwidth holographic microscopy which exploits high-throughput label-free quantitative phase image. We introduce Kramers–Kronig relations to the off-axis multiplexing technology. Based the analyticity of band-limited signal under diffraction-limited system, the maximum space bandwidth utilization in single multiplexing hologram is increased to 78.5%. Secondly, by assisting with off-axis optimized initial phase in the phase retrieval, high-resolution and full-field reconstruction by exploiting the full bandwidth are demonstrated for complex-amplitude reconstruction. Off-axis optimization phase provides an effective initial guess to avoid stagnation and minimize the required measurements of multi-plane phase retrieval. Different tumor types and a variety of precursor lesions and pathologies can be visualized with label-free specimens.
Digital holographic imaging has the characteristics of fast and flexible with simple set up, and it can quantitatively obtain the intensity and phase of objects. The resolution of the reconstructed image is greatly limited by the pixelated imaging detectors during the digitization processing of holograms. Due to the limited diffraction bandwidth, the diffracted beam of each object point can be viewed as a diffractive cone. The lack of diffraction components causes the reconstructed quality to decrease when the detector cannot collect a complete diffracted wave field in the inline holography. In this work, we studied the reconstructed quality of holograms under different sampling forms. The losing diffraction components can be reconstructed by using an iterative algorithm based on energy attenuation and support constraints. We propose three iterative methods. The first is the bicubic interpolation and extrapolation iterative method based on a single small detector. The second is multi-plane extrapolation iterative method. The third is a faithful iterative reconstruction based on a sparse sensor array. When the diffraction component recorded by the hologram is missing, the losing diffraction components can be reconstructed by using the principle of the holographic redundancy. The reduction of reconstruction quality caused by the loss of sampling in the small-sized detector and sparse sensor array in the digital holography can be compensated.
Compressive sensing (CS) has been used in in-line digital holography (DH) to eliminate the noise, especially the interference caused by twin image. In this work, we combine the two-step iterative shrinkage-thresholding (TwIST) algorithm in CS and autofocusing methods to accomplish high-resolution imaging from a single-exposure hologram. We preprocess all the images within a reconstruction distance through TwIST algorithm, and then evaluate the focal plane of the images according to the focusing functions including the Laplace operator and the absolute gradient operator, etc. The proposed method can not only effectively eliminate twin image to improve the imaging quality, but also perform unique advantages to estimate the in-focus distance in DH.
Digital holography enables the digitization processing of holograms. The resolution of the reconstructed image is greatly limited by the pixelated imaging detectors. This work investigates the effect of the initial hologram size on the imaging point spread function and introduces a bicubic interpolation and extrapolation iterative (BIPEPI) method. It circumvented the recording limitation in a certain extent to obtain more wave field information beyond the experimental recording area. The bicubic interpolation (BIP) method increases the pixel density inside the hologram to enhance the low-frequency terms of the object. With extrapolation iterative (EPI) method, more high order fringes around the experimental hologram are generated to enhance the high-frequency terms of the object. This method can improve the point spread function of small size detector to effectively increase the reconstructed resolution.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.