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Holographic structured illumination combined with optogenetics enables patterned stimulation of neurons and glial cells in an intact living brain. Moreover, in vivo functional imaging of cellular activity with recent advanced microscope technologies allows for visualization of the cellular responses during learning, emotion and cognition. Integrating these techniques can be used to verify the link between cell function and behavior output. However, there are technical limitations to stimulate multiple cells with high spatial and temporal resolution with available techniques of optogenetic stimulation. Here, we summarized a two-photon microscope combined with holographic system to stimulate multiple cells with high spatial and temporal resolution for living mice and their biological application.

Defect detection requires highly sensitive and robust inspection methods. This study shows that non-overlapping illumination patterns can improve the noise robustness of deep learning ghost imaging (DLGI) without modifying the convolutional neural network (CNN). Ghost imaging (GI) can be accelerated by combining GI and deep learning. However, the robustness of DLGI decreases in exchange for higher speed. Using non-overlapping patterns can decrease the noise effects in the input data to the CNN. This study evaluates the DLGI robustness by using non-overlapping patterns generated based on binary notation. The results show that non-overlapping patterns improve the position accuracy by up to 51%, enabling the detection of defect positions with higher accuracy in noisy environments.

A multi-view phase measurement system based on single-shot phase-shifting digital holography is proposed to dynamically obtain three-dimensional (3-D) information of an unstable temperature field. The proposed system consists of a laser, three polarization imaging cameras, and the corresponding optical components. The laser beam emitted from the laser is separated by the fibers into three pairs that contain three object beams and three reference beams. The object beams pass through the object in three different directions and interfere with the reference beams at the image sensor plane respectively. The recording of the three cameras is triggered simultaneously, which enables the phase measurement of dynamic objects from different viewpoints. We successfully measured the 3-D distributions of an unstable temperature field in the experiments with the proposed system.

We explore the contribution of convolutional neural networks to correcting for the effect of the point spread function (PSF) of the optics when applying ghost imaging (GI) combined with deep learning to identify defect positions in materials. GI can be accelerated by combining GI and deep learning. However, no method has been established for determining the relevant model parameters. A simple model with different kernel sizes was built. Its accuracy was evaluated for data containing the effects of different PSFs. Numerical analysis and empirical experiments demonstrate that the accuracy of defect identification improved by matching the kernel size with the PSF of the optics.

Recent advances in optical bioimaging and optogenetics have enabled the visualization and manipulation of biological phenomena, including cellular activities, in living animals. In the field of neuroscience, detailed neural activity related to brain functions, such as learning and memory, has now been revealed, and it has become feasible to artificially manipulate this activity to express brain functions. However, the conventional evaluation of neural activity by two-photon Ca

Multimodal optical microscopy combines different optical and physiological principles working together to obtain rich perspectives from a single biological event. In this paper, the recent advances in multimodal microscopy systems based on off-axis digital holography and transport-of-intensity equation are reviewed. Both methods used the common-path configuration, and realized simultaneous quantitative phase and fluorescence imaging in 3D space. Feasibility checks with fluorescent micro-beads and live plant cells are presented. The results show that both methods are capable of fast acquisition of the quantitative phase and fluorescence information with digital refocusing ability.

Light-field three-dimensional (3D) fluorescence microscopes can acquire 3D fluorescence images in a single shot, and followed numerical reconstruction can realize cross-sectional imaging at an arbitrary depth. The typical configuration that uses a lens array and a single image sensor has the trade-off between depth information acquisition and spatial resolution of each cross-sectional image. The spatial resolution of the reconstructed image degrades when depth information increases. In this paper, we use U-net as a deep learning model to improve the quality of reconstructed images. We constructed an optical system that integrates a light-field microscope and an epifluorescence microscope, which acquire the light-field data and high-resolution two-dimensional images, respectively. The high-resolution images from the epifluorescence microscope are used as ground-truth images for the training dataset for deep learning. The experimental results using fluorescent beads with a size of 10 µm and cultured tobacco cells showed significant improvement in the reconstructed images. Furthermore, time-lapse measurements were demonstrated in tobacco cells to observe the cell division process.

This Feature Issue of Optics Express is organized in conjunction with the 2022 Optica conference on 3D Image Acquisition and Display: Technology, Perception and Applications which was held in hybrid format from 11 to 15, July 2022 as part of the Imaging and Applied Optics Congress and Optical Sensors and Sensing Congress 2022 in Vancouver, Canada. This Feature Issue presents 31 articles which cover the topics and scope of the 2022 3D Image Acquisition and Display conference. This Introduction provides a summary of these published articles that appear in this Feature Issue.

To reduce the number of measurements of motionless optical scanning holography (MOSH), a two-step phase-shifting technique is proposed. The numerical simulation results show the proposed method can reconstruct the comparable distribution compared with the four-step method.

We proposed an optical method for imaging of a motion picture of sounds for selected frequency. We recorded three sounds of frequencies 39.5, 40.0, and 40.5 kHz with the frame rate of 100,000 fps by parallel phase-shifting digital holography and succeeded in imaging the sound for selected frequency.

We propose a method for improving the sensitivity in measurement of sound pressure with parallel phase-shifting digital holography by time-frequency filtering. We succeeded in measuring of acoustic wave at 97.75 dB sound pressure level.

A novel off-axis incoherent digital holographic microscopy using polarization gratings and a geometric phase lens is proposed. The polarization gratings and geometric phase lens works to the left and right handed circular polarized light differently. The preliminary experiment result using a micro-fluorescence bead is presented.

We propose the method for imaging of temperature distribution by using parallel phase-shifting digital holography. The proposed method was experimentally demonstrated by recording the temperature distribution around a soldering iron.

We propose digital light-in-flight recording by holography that uses a biological specimen as a diffuser. By the proposed method, we successfully recorded a motion picture of light pulse propagating through a slice of pork.

To see through a random light field in real-time, single-shot generalized Hanbury Brown–Twiss experiments using a polarization camera are proposed. The target intensity distribution is obtained from a complex coherence function which is calculated from auto-correlation and cross correlation functions of phase-shifted speckle intensity distributions. The phase-shifted speckle intensity distributions are simultaneously obtained through a strategy of parallel phase-shifting digital holography. Experimental results show that the proposed method can image a moving object in a random light field using a measured complex coherence function through the van Cittert–Zernike theorem.

A spectral-domain optical coherence microscope (SD-OCM) embedded by a digital phase conjugation is presented for high-resolution imaging of objects behind a weakly scattering medium. For high-resolution SD-OCM, keeping a narrow focusing spot even in a scattering medium is important. To compensate for the degradation of the focused spot due to the scattering, digital phase conjugation with a low-coherent light is introduced by measuring the distorted wavefront of coherent light and making wavelength conversion due to the difference between the coherent and low-coherent light beams. Experiments using a weakly scattering sheet with a scattering angle of 30 degrees showed us to improve the focused spot property and enhance the reflected intensity signal. We also demonstrate the feasibility of the system for the imaging of objects with periodic reflectance structures of 10 µm width.

Spatiotemporal information about light pulse propagation obtained with femtosecond temporal resolution plays an important role in understanding transient phenomena and light–matter interactions. Although ultrafast optical imaging techniques have been developed, it is still difficult to capture light pulse propagation spatiotemporally. Furthermore, imaging through a three-dimensional (3-D) scattering medium is a longstanding challenge due to the optical scattering caused by the interaction between light pulse and a 3-D scattering medium. Here, we propose a technique for ultrafast optical imaging of light pulses propagating inside a 3D scattering medium. We record an image of the light pulse propagation using the ultrashort light pulse even when the interaction between light pulse and a 3-D scattering medium causes the optical scattering. We demonstrated our proposed technique by recording converging, refracted, and diffracted propagating light for 59 ps with femtosecond temporal resolution.

This paper proposed a holographic optical element as a see-through screen for the computer-generated hologram projection system with 3D images. The proposed holographic screen consisted of a linear grating and a lens phase. The linear grating is used to redirect the information light and guide information into the observer's eye and achieve the see-through function. The lens phase is used to magnify the field of view of the holographic projection system. The aberration caused by the screen was analyzed in this paper and the aberration can be pre-corrected in the hologram calculation algorithm. Finally, the proposed system achieved 20.3 by 14.3 degrees field of view at 532 nm laser based on the spatial light modulator with 6.4 µm pixels.

We have proposed a new configuration of the single-shot, dual-wavelength, common-path, off-axis DHM system. The proposed system is used for decoupling the refractive index and thickness of a biological specimen.

Sound is an important invisible physical phenomenon that needs to be explained in several physical and biological processes, along with visual phenomena. For this purpose, multiparameter digital holography (DH) has been proposed to visualize both features simultaneously due to the phase and amplitude reconstruction properties of DH. In this paper, we present a brief review on sound field imaging techniques with special focus on the multiparameter imaging capability of DH for visualizing sound and visual features. The basic theory and several experimental results with very high-speed recordings are also presented to demonstrate sound field imaging for the audible range as well as in the ultrasound range.

Upregulation of N-type Ca2+ channel dependent subunits increases functional connections and synchronization for pain formation., Sustained neuropathic pain from injury or inflammation remains a major burden for society. Rodent pain models have informed some cellular mechanisms increasing neuronal excitability within the spinal cord and primary somatosensory cortex (S1), but how activity patterns within these circuits change during pain remains unclear. We have applied multiphoton in vivo imaging and holographic stimulation to examine single S1 neuron activity patterns and connectivity during sustained pain. Following pain induction, there is an increase in synchronized neuronal activity and connectivity within S1, indicating the formation of pain circuits. Artificially increasing neuronal activity and synchrony using DREADDs reduced pain thresholds. The expression of N-type voltage-dependent Ca2+ channel subunits in S1 was increased after pain induction, and locally blocking these channels reduced both the synchrony and allodynia associated with inflammatory pain. Targeting these S1 pain circuits, via inhibiting N-type Ca2+ channels or other approaches, may provide ways to reduce inflammatory pain.

The demand for single-shot and common-path holographic systems has become increasingly important in recent years, as such systems offer various advantages compared to their counterparts. Single-shot holographic systems, for example, reduce computational complexity as only a single hologram with the object information required to process, making them more suitable for the investigation of dynamic events; and common-path holographic systems are less vibration-sensitive, compact, inexpensive, and high in temporal phase stability. We have developed a single-shot common-path off-axis digital holographic setup based on a beam splitter and pinhole. In this paper, we present a concise review of the proposed digital holographic system for several applications, including the quantitative phase imaging to investigate the morphological and quantitative parameters, as a metrological tool for testing of micro-optics, industrial inspection and measurement, and sound field imaging and visualization.

Guest editors Toyohiko Yatagai, Osamu Matoba, Yoshihisa Aizu, Yasuhiro Awatsuji, and Yuan Luo introduce the articles in the Special Series on Biomedical Imaging and Sensing.

Integrated multimodal cross-sectional or volumetric imaging techniques give us fruitful information to understand the behavior or status of target objects such as biological samples. Most of the reported systems for this purpose are either time consuming due to scanning or use additional reference beams such as in interferometry. Therefore, fast, simple, highly efficient, and powerful multimodal imaging systems that can perform cross-sectional imaging with simple algorithms are worth to be investigated. In this paper, a multimodal technique for cross-sectional quantitative phase and fluorescence imaging with computational microscopy is presented. We combine cross-sectional fluorescence and quantitative phase imaging by using the transport of intensity equation (TIE) and numerical wave propagation. The amplitude and phase of the fluorescence light wave with partially spatial coherence are obtained from three defocused intensity patterns. The proposed hybrid imaging system is simple, compact, and non-iterative. We present experimental results of microbeads and fluorescent proteinlabeled living cells of the moss Physcomitrella patensto demonstrate the performance of the proposed imaging system.