Roadmap on computational methods in optical imaging and holography [invited].

Unlabelled: Computational methods have been established as cornerstones in optical imaging and holography in recent years. Every year, the dependence of optical imaging and holography on computational methods is increasing significantly to the extent that optical methods and components are being completely and efficiently replaced with computational methods at low cost. This roadmap reviews the current scenario in four major areas namely incoherent digital holography, quantitative phase imaging, imaging through scattering layers, and super-resolution imaging.

Toward Accurate Photoluminescence Nanothermometry Using Rare-Earth Doped Nanoparticles for Biomedical Applications.

ConspectusPhotoluminescence nanothermometry can detect the local temperature at the submicrometer scale with minimal contact with the object under investigation. Owing to its high spatial resolution, this technique shows great potential in biomedicine in both fundamental studies as well as preclinical research. Photoluminescence nanothermometry exploits the temperature-dependent optical properties of various nanoscale optical probes including organic fluorophores, quantum dots, and carbon nanostructures.

Spatial-temporal characterization of photoemission in a streak-mode dynamic transmission electron microscope.

A long-standing motivation driving high-speed electron microscopy development is to capture phase transformations and material dynamics in real time with high spatial and temporal resolution. Current dynamic transmission electron microscopes (DTEMs) are limited to nanosecond temporal resolution and the ability to capture only a few frames of a transient event. With the motivation to overcome these limitations, we present our progress in developing a streak-mode DTEM (SM-DTEM) and demonstrate the recovery of picosecond images with high frame sequence depth.

Swept coded aperture real-time femtophotography.

Single-shot real-time femtophotography is indispensable for imaging ultrafast dynamics during their times of occurrence. Despite their advantages over conventional multi-shot approaches, existing techniques confront restricted imaging speed or degraded data quality by the deployed optoelectronic devices and face challenges in the application scope and acquisition accuracy. They are also hindered by the limitations in the acquirable information imposed by the sensing models.

Tutorial on compressed ultrafast photography.

Significance: Compressed ultrafast photography (CUP) is currently the world's fastest single-shot imaging technique. Through the integration of compressed sensing and streak imaging, CUP can capture a transient event in a single camera exposure with imaging speeds from thousands to trillions of frames per second, at micrometer-level spatial resolutions, and in broad sensing spectral ranges.

Aim: This tutorial aims to provide a comprehensive review of CUP in its fundamental methods, system implementations, biomedical applications, and prospect.

Short-wave Infrared Photoluminescence Lifetime Mapping of Rare-Earth Doped Nanoparticles Using All-Optical Streak Imaging.

The short-wave infrared (SWIR) photoluminescence lifetimes of rare-earth doped nanoparticles (RENPs) have found diverse applications in fundamental and applied research. Despite dazzling progress in the novel design and synthesis of RENPs with attractive optical properties, existing optical systems for SWIR photoluminescence lifetime imaging are still considerably restricted by inefficient photon detection, limited imaging speed, and low sensitivity. To overcome these challenges, SWIR photoluminescence lifetime imaging microscopy using an all-optical streak camera (PLIMASC) is developed.

Temporal resolution of ultrafast compressive imaging using a single-chirped optical probe.

Ultrafast compressive imaging captures three-dimensional spatiotemporal information of transient events in a single shot. When a single-chirped optical probe is applied, the temporal information is obtained from the probe modulated in amplitude or phase using a direct frequency-time mapping method. Here, we extend the analysis of the temporal resolution of conventional one-dimensional ultrafast measurement techniques such as spectral interferometry to that in three-dimensional ultrafast compressive imaging.

Optical single-pixel volumetric imaging by three-dimensional light-field illumination.

Three-dimensional single-pixel imaging (3D SPI) has become an attractive imaging modality for both biomedical research and optical sensing. 3D-SPI techniques generally depend on time-of-flight or stereovision principle to extract depth information from backscattered light. However, existing implementations for these two optical schemes are limited to surface mapping of 3D objects at depth resolutions, at best, at the millimeter level.

Compressed ultrahigh-speed single-pixel imaging by swept aggregate patterns.

Single-pixel imaging (SPI) has emerged as a powerful technique that uses coded wide-field illumination with sampling by a single-point detector. Most SPI systems are limited by the refresh rates of digital micromirror devices (DMDs) and time-consuming iterations in compressed-sensing (CS)-based reconstruction. Recent efforts in overcoming the speed limit in SPI, such as the use of fast-moving mechanical masks, suffer from low reconfigurability and/or reduced accuracy.

Multi-scale band-limited illumination profilometry for robust three-dimensional surface imaging at video rate.

Dynamic three-dimensional (3D) surface imaging by phase-shifting fringe projection profilometry has been widely implemented in diverse applications. However, existing techniques fall short in simultaneously providing the robustness in solving spatially isolated 3D objects, the tolerance of large variation in surface reflectance, and the flexibility of tunable working distances with meter-square-level fields of view (FOVs) at video rate. In this work, we overcome these limitations by developing multi-scale band-limited illumination profilometry (MS-BLIP).

Single-shot compressed optical field topography.

Femtosecond lasers are powerful in studying matter's ultrafast dynamics within femtosecond to attosecond time scales. Drawing a three-dimensional (3D) topological map of the optical field of a femtosecond laser pulse including its spatiotemporal amplitude and phase distributions, allows one to predict and understand the underlying physics of light interaction with matter, whose spatially resolved transient dielectric function experiences ultrafast evolution. However, such a task is technically challenging for two reasons: first, one has to capture in single-shot and squeeze the 3D information of an optical field profile into a two-dimensional (2D) detector; second, typical detectors are only sensitive to intensity or amplitude information rather than phase.

High-speed super-resolution imaging with compressive imaging-based structured illumination microscopy.

Structured illumination microscopy (SIM) has been widely applied to investigating fine structures of biological samples by breaking the optical diffraction limitation. So far, video-rate imaging has been obtained in SIM, but the imaging speed was still limited due to the reconstruction of a super-solution image through multi-sampling, which hindered the applications in high-speed biomedical imaging. To overcome this limitation, here we develop compressive imaging-based structured illumination microscopy (CISIM) by synergizing SIM and compressive sensing (CS).

Compressed ultrafast tomographic imaging by passive spatiotemporal projections.

Existing streak-camera-based two-dimensional (2D) ultrafast imaging techniques are limited by long acquisition time, the trade-off between spatial and temporal resolutions, and a reduced field of view. They also require additional components, customization, or active illumination. Here we develop compressed ultrafast tomographic imaging (CUTI), which passively records 2D transient events with a standard streak camera.

Punching holes in light: recent progress in single-shot coded-aperture optical imaging.

Single-shot coded-aperture optical imaging physically captures a code-aperture-modulated optical signal in one exposure and then recovers the scene via computational image reconstruction. Recent years have witnessed dazzling advances in various modalities in this hybrid imaging scheme in concomitant technical improvement and widespread applications in physical, chemical and biological sciences. This review comprehensively surveys state-of-the-art single-shot coded-aperture optical imaging.

Camera-free three-dimensional dual photography.

We report camera-free three-dimensional (3D) dual photography. Inspired by the linkage between fringe projection profilometry (FPP) and dual photography, we propose to implement coordinate mapping to simultaneously sense the direct component of the light transport matrix and the surface profiles of 3D objects. By exploiting Helmholtz reciprocity, dual photography and scene relighting can thus be performed on 3D images.

Single-shot stereo-polarimetric compressed ultrafast photography for light-speed observation of high-dimensional optical transients with picosecond resolution.

Simultaneous and efficient ultrafast recording of multiple photon tags contributes to high-dimensional optical imaging and characterization in numerous fields. Existing high-dimensional optical imaging techniques that record space and polarization cannot detect the photon's time of arrival owing to the limited speeds of the state-of-the-art electronic sensors. Here, we overcome this long-standing limitation by implementing stereo-polarimetric compressed ultrafast photography (SP-CUP) to record light-speed high-dimensional events in a single exposure.

A cellular endolysosome-modulating pore-forming protein from a toad is negatively regulated by its paralog under oxidizing conditions.

Endolysosomes are key players in cell physiology, including molecular exchange, immunity, and environmental adaptation. They are the molecular targets of some pore-forming aerolysin-like proteins (ALPs) that are widely distributed in animals and plants and are functionally related to bacterial toxin aerolysins. βγ-CAT is a complex of an ALP (BmALP1) and a trefoil factor (BmTFF3) in the firebelly toad ().

Single-shot ultrafast imaging attaining 70 trillion frames per second.

Real-time imaging of countless femtosecond dynamics requires extreme speeds orders of magnitude beyond the limits of electronic sensors. Existing femtosecond imaging modalities either require event repetition or provide single-shot acquisition with no more than 10 frames per second (fps) and 3 × 10 frames. Here, we report compressed ultrafast spectral photography (CUSP), which attains several new records in single-shot multi-dimensional imaging speeds.

Snapshot Photoacoustic Topography Through an Ergodic Relay for High-throughput Imaging of Optical Absorption.

Current embodiments of photoacoustic imaging require either serial detection with a single-element ultrasonic transducer or parallel detection with an ultrasonic array, necessitating a trade-off between cost and throughput. Here, we present photoacoustic topography through an ergodic relay (PATER) for low-cost high-throughput snapshot widefield imaging. Encoding spatial information with randomized temporal signatures through ergodicity, PATER requires only a single-element ultrasonic transducer to capture a widefield image with a single laser shot.

Real-time high-speed three-dimensional surface imaging using band-limited illumination profilometry with a CoaXPress interface.

High-speed three-dimensional (3D) surface imaging by structured-light profilometry is currently driven by numerous applications. However, the limited speeds in fringe pattern projection, image acquisition, and data transmission have strained the existing methods from reaching kilohertz-level acquisition, processing, and display of 3D information during the occurrence of dynamic events (i.e.

Picosecond-resolution phase-sensitive imaging of transparent objects in a single shot.

With the growing interest in the optical imaging of ultrafast phenomena in transparent objects, from shock wave to neuronal action potentials, high contrast imaging at high frame rates has become desirable. While phase sensitivity provides the contrast, the frame rates and sequence depths are highly limited by the detectors. Here, we present phase-sensitive compressed ultrafast photography (pCUP) for single-shot real-time ultrafast imaging of transparent objects by combining the contrast of dark-field imaging with the speed and the sequence depth of CUP.

Comparative analysis of diverse toxins from a new pharmaceutical centipede, .

As the oldest venomous animals, centipedes use their venom as a weapon to attack prey and for protection. Centipede venom, which contains many bioactive and pharmacologically active compounds, has been used for centuries in Chinese medicine, as shown by ancient records. Based on comparative analysis, we revealed the diversity of and differences in centipede toxin-like molecules , a substitute pharmaceutical material used in China, and .

Single-shot compressed optical-streaking ultra-high-speed photography.

Single-shot ultra-high-speed imaging is of great significance to capture transient phenomena in physics, biology, and chemistry in real time. Existing techniques, however, have a restricted application scope, a low sequence depth, or a limited pixel count. To overcome these limitations, we developed single-shot compressed optical-streaking ultra-high-speed photography (COSUP) with an imaging speed of 1.