Author(s):

Suzuki, Takakazu; Nemoto, Hirofumi; Takasawa, Kazuki & Kannari, Fumihiko

Abstract:

“We demonstrated real-time, in-situ operation of a single-shot, frequency-time-encoding burst imaging method of sequentially timed all-optical mapping photography utilizing spectral filtering (SF-STAMP) by employing a high-speed camera with the frame rate of a 1000 fps as a detector. We obtained single-shot burst images of a pulse-by-pulse femtosecond laser ablation of a glass by a chirped probe laser pulse with a 1–2-ps frame interval or by a spectrally sweeping burst laser pulse train with a 300-ps interval. We observed burst images of plasma generation during the early stage of laser ablation in a glass with a short frame interval by a chirped probe laser pulse. We also captured burst images of plume and shock-wave generation in air with a 1.5-ns observation time window by a spectrally sweeping probe laser pulse train.”

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Author(s):

Chen, Zhenyue; Mc Larney, Benedict; Rebling, Johannes; Deán-Ben, Xosé Luis; Zhou, Quanyu; Gottschalk, Sven & Razansky, Daniel

Abstract:

“Abstract Scanning optical microscopy techniques are commonly restricted to a sub-millimeter field-of-view (FOV) or otherwise employ slow mechanical translation, limiting their applicability for imaging fast biological dynamics occurring over large areas. A rapid scanning large-field multifocal illumination (LMI) fluorescence microscopy technique is devised based on a beam-splitting grating and an acousto-optic deflector synchronized with a high-speed camera to attain real-time fluorescence microscopy over a centimeter-scale FOV. Owing to its large depth of focus, the approach allows noninvasive visualization of perfusion across the entire mouse cerebral cortex, not achievable with conventional wide-field fluorescence microscopy methods. The new concept can readily be incorporated into conventional wide-field microscopes to mitigate image blur due to tissue scattering and attain optimal trade-off between spatial resolution and FOV. It further establishes a bridge between conventional wide-field macroscopy and laser scanning confocal microscopy, thus it is anticipated to find broad applicability in functional neuroimaging, in vivo cell tracking, and other applications looking at large-scale fluorescent-based biodynamics.”

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Author(s):

Krmpot, Aleksandar J.; Nikolić, Stanko N.; Oasa, Sho; Papadopoulos, Dimitrios K.; Vitali, Marco; Oura, Makoto; Mikuni, Shintaro; Thyberg, Per; Tisa, Simone; Kinjo, Masataka; Nilsson, Lennart; Terenius, Lars; Rigler, Rudolf & Vukojevic, Vladana

Abstract:

“Functional fluorescence microscopy imaging (fFMI), a time-resolved (21 μs/frame) confocal fluorescence microscopy imaging technique without scanning, is developed for quantitative characterization of fast reaction-transport processes in solution and in live cells. The method is based on massively parallel fluorescence correlation spectroscopy (FCS). Simultaneous excitation of fluorescent molecules in multiple spots in the focal plane is achieved using a diffractive optical element (DOE). Fluorescence from the DOE-generated 1024 illuminated spots is detected in a confocal arrangement by a matching matrix detector comprising 32 × 32 single-photon avalanche photodiodes (SPADs). Software for data acquisition and fast auto- and cross-correlation analysis by parallel signal processing using a graphic processing unit (GPU) allows temporal autocorrelation across all pixels in the image frame in 4 s and cross-correlation between first- and second-order neighbor pixels in 45 s. We present here this quantitative, time-resolved imaging method with single-molecule sensitivity and demonstrate its usefulness for mapping in live cell location-specific differences in the concentration and translational diffusion of molecules in different subcellular compartments. In particular, we show that molecules without a specific biological function, e.g., the enhanced green fluorescent protein (eGFP), exhibit uniform diffusion. In contrast, molecules that perform specialized biological functions and bind specifically to their molecular targets show location-specific differences in their concentration and diffusion, exemplified here for two transcription factor molecules, the glucocorticoid receptor (GR) before and after nuclear translocation and the Sex combs reduced (Scr) transcription factor in the salivary gland of Drosophila ex vivo.”

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Author(s):

Guo, Zhenkun; Zhou, Ninghao; Williams, Olivia F.; Hu, Jun; You, Wei & Moran, Andrew M.

Abstract:

“Carrier diffusion is imaged in a perovskite film and crystal using a newly developed transient absorption microscope. Wide-field imaging is combined with a diffractive optic-based beam geometry to conduct 41 transient absorption experiments in parallel in this experimental setup. This configuration allows statistics to be quickly compiled with a 1 kHz laser system. Diffusion coefficients of 0.01 and 0.20 cm2/s are obtained for the methylammonium lead iodide film and crystal, respectively. Our data suggest that the dynamics in the film are dominated by intensity dependence of the carrier lifetimes as opposed to carrier diffusion. The small diffusion coefficients determined in the film are attributed to the presence of grain boundaries.”

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Author(s):

Suzuki, Takakazu; Hida, Ryohei; Yamaguchi, Yuki; Nakagawa, Keiichi; Saiki, Toshiharu & Kannari, Fumihiko

Abstract:

“We captured ultrafast two-dimensional (2D)-burst images of the crystalline-to-amorphous phase transition of Ge2Sb2Te5. These transitions were induced by a femtosecond laser pulse, and the images, with a sub-picosecond temporal resolution, were acquired on a single-shot basis through the change in local optical transmittance. We employed a 2D-burst imaging method of sequentially timed all-optical mapping photography utilizing spectral filtering (SF-STAMP). The SF-STAMP system consists of a 25-beam-generating diffractive optical element, a band-pass filter, and two Fourier transform lenses. We used a frequency-chirped broadband pulse and achieved 25-frame burst imaging with an interval of 133 fs in a single-shot time window of 3.2 ps.”

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Author(s):

Indrišiūnas, Simonas; Voisiat, Bogdan; Gedvilas, Mindaugas; Račiukaitis, Gediminas

Abstract:

“Fabrication of photonic devices requires fast and reliable microstructuring approach. For example, efficient generation of fine 2D patterns in thin metal films is needed in plasmonic metamaterial devices. In this paper, the authors present an approach for the flexible generation of the periodic pattern using a laser beam interference patterning setup. So far, interference patterning was mostly limited to the periodic patterns of lines and dots. A variety of interference patterns can be significantly increased by controlling the polarization orientation of each interfering beam. The authors demonstrate the experimental setup for polarization control in the confocal six-beam interference configuration. Various periodic intensity patterns were generated and observed with a CCD camera using this setup. Additionally, the generated patterns were replicated in a thin metal film experimentally. Efficient and simple fabrication process and relatively high patterning flexibility suggest that interference patterning with polarization control may become an important tool in metamaterial fabrication.”

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