High-resolution light-field imaging via phase space retrieval

Analysis of the hybrid light field reconstruction and comparison with Richardson-Lucy Light Field Deconvolution

Conventional microscopes have a high spatial resolution and a low depth-of-field. Light field microscopes have a high depth-of-field but low spatial resolution. A new hybrid approach uses information from both systems to reconstruct a high-resolution light field [Appl. Opt.58, A142 (2019)APOPAI0003-693510.1364/AO.58.00A142]. The resolution of the resulting light field is said to be limited only by diffraction and the size of the pixels. In this paper, we evaluate this method. Using simulation data we compare the output of the hybrid reconstruction algorithm with its simulated ground truth. Our analyses reveal that the observed improvement in the light field quality is not a consequence of data fusion or incorporation of information from a conventional camera, but rather the results of an intermediate interpolation step within the light field itself. This suggests that the required information is already inherent to the light field. By employing the Richardson-Lucy Light Field Deconvolution algorithm, we demonstrate that existing algorithms have already utilized this information.

Improving image resolution on point-like sources in a type 1 light-field camera

A ray-trace simulation of a type 1 light-field imager is used to show that resolutions significantly better than the lenslet scale can be deterministically reached in reconstructed images of isolated point-like sources. This is enabled by computationally projecting the system pupil onto the lenslet-array plane to better estimate the lenslet-plane-crossing locations through which the rays from a point source have passed on their way to the detector array. Improving light-field type 1 image resolution from the lenslet scale to the pixel scale can significantly enhance signal-to-noise ratios on faint point-like sources such as fluorescent microbes, making the technique of interest in, e.g., in situ microbial life searches in extreme environments.

Three-Dimensional Imaging in Stem Cell-Based Researches

Stem cells have an important role in regenerative therapies, developmental biology studies and drug screening. Basic and translational research in stem cell technology needs more detailed imaging techniques. The possibility of cell-based therapeutic strategies has been validated in the stem cell field over recent years, a more detailed characterization of the properties of stem cells is needed for connectomics of large assemblies and structural analyses of these cells. The aim of stem cell imaging is the characterization of differentiation state, cellular function, purity and cell location. Recent progress in stem cell imaging field has included ultrasound-based technique to study living stem cells and florescence microscopy-based technique to investigate stem cell three-dimensional (3D) structures. Here, we summarized the fundamental characteristics of stem cells via 3D imaging methods and also discussed the emerging literatures on 3D imaging in stem cell research and the applications of both classical 2D imaging techniques and 3D methods on stem cells biology.

wFLFM: enhancing the resolution of Fourier light-field microscopy using a hybrid wide-field image

We introduce wFLFM, an approach that enhances the resolution of Fourier light-field microscopy (FLFM) through a hybrid wide-field image. The system exploits the intrinsic compatibility of image formation between the on-axis FLFM elemental image and the wide-field image, allowing for minimal instrumental and computational complexity. The numerical and experimental results of wFLFM present a two- to three-fold improvement in the lateral resolution without compromising the 3D imaging capability in comparison with conventional FLFM.

High-resolution 3D light-field imaging

SIGNIFICANCE

High-speed 3D imaging methods have been playing crucial roles in many biological discoveries.

AIM

We present a hybrid light-field imaging system and image processing algorithm that can visualize high-speed biological events.

APPROACH

The hybrid light-field imaging system uses the selective plane optical illumination, which simultaneously records a high-resolution 2D image and a low-resolution 4D light-field image. The high-resolution 4D light-field image is obtained by applying the hybrid algorithm derived from the deconvolution and phase retrieval methods.

RESULTS

High-resolution 3D imaging at a speed of 100-s volumes per second over an imaging field of 250  ×  250  ×  80  μm3 in the x, y, and z axis, respectively, is achieved with a 2.5 times enhancement in lateral resolution over the entire imaging field compared with standard light-field systems. In comparison to the deconvolution algorithm, the hybrid algorithm addresses the artifact issue at the focal plane and reduces the computation time by a factor of 4.

CONCLUSIONS

The new hybrid light-field imaging method realizes high-resolution and ultrafast 3D imaging with a compact setup and simple algorithm, which may help discover important applications in biophotonics to visualize high-speed biological events.