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Label-free optical diffraction tomography (ODT), an imaging technology that does not require fluorescent labeling or other pre-processing, can overcome the limitations of conventional cell imaging technologies, such as fluorescence and electron microscopy. In this study, we used ODT to characterize the cellular organelles of three different stem cells-namely, human liver derived stem cell, human umbilical cord matrix derived mesenchymal stem cell, and human induced pluripotent stem cell-based on their refractive index and volume of organelles. The physical property of each stem cell was compared with that of fibroblast. Based on our findings, the characteristic physical properties of specific stem cells can be quantitatively distinguished based on their refractive index and volume of cellular organelles. Altogether, the method employed herein could aid in the distinction of living stem cells from normal cells without the use of fluorescence or specific biomarkers.

The plasmonic coupling, the enhanced electromagnetic field occurring through a uniform and small separation between metallic particles, is required for better application to localized surface plasmon resonance. Graphene has been studied as a good spacer candidate because of its precise controllability at subnanoscale. Here, the enhancement of plasmonic coupling among metallic nanoparticles (NPs) uniformly spread out on both sides of a graphene spacer is experimentally and simulatively investigated. Additionally, the post-evaporated flat structure is rippled along one direction to reduce the separation between nanoparticles. As the amount of rippling increases, the enhancement factor (EF) of the plasmonic coupling increases almost linearly or quadratically depending on the size of nanoparticles. Such a highly rippled nanostructure is believed to not only increase the plasmonic coupling in either side of the spacer but lead to a higher density of “hot spots” through the spacer gap also. The observed EFs of a structure with the MLG spacer are consistent with the simulation results obtained from the classical electrodynamics. On the other hand, the SLG case appears to be inconsistent with such a classical approach, indicating that the plasmon tunneling through the thin barrier is prevalent in the case of the SLG spacer.

This paper deals with the development of a relief robot system that can provide first aid to the injured person by remote control in disaster environment and battlefield. To perform safe first aid, relief robot has hardware and controller that can feed back the contact force while following the command of remote controller. In addition, a controller capable of maintaining system stability under the influence of time delay and packet loss due to communication state during remote control is mounted. The developed relief robot system is evaluated through experiments simulating actual first aid procedures.

We have researched a gondola typed robot system for building facade maintenance. Its main application is to paint on building facade. To apply a robot system to the painting tool,recognition of building wall shape should be preceded. In this paper, we proposed a limit switch module as a mechanical sensor method. As experiments, we applied the proposed module to window and obstac le on wall with attitude reference sensor (ARS) and laser height sensor (distance sensor).

Exoskeleton robots have been used for rehabilitation in many areas. In order to comprise arm exoskeleton robot, a modular joint unit is proposed. As a module, this unit contains everything for joint actuating. Motor, encoder, harmonic drive, brake, cross roller bearing, and joint torque sensor are included in this unit. Because this unit is applied to exoskeleton robot, the joint torque sensor is important for human machine interface (HMI). Joint torque sensor performance is verified with FEM analysis.

For force control of robot and collision detection with humans, robots that has joint torque sensors have been developed. However, existing torque sensors cannot measure correct torque because of crosstalk error. In order to solve this problem, we proposed a novel torque sensor that can measure the pure torque without crosstalk. The hexaform of the proposed sensor with truss structure increase deformation of the sensor and restoration, and the Wheatstone bridge circuit of strain gauge removes crosstalk error. Sensor performance is verified with FEM analysis.

We demonstrate a novel experimental method for improvement of efficiency of structural surface modification of various solids (PMMA, amorphous carbon) achieved by simultaneous action of XUV (21.6 nm), obtained from high-order harmonic generation (HHG), and VIS-NIR (410/820 nm) laser pulses. Although the fluence of each individual pulse was far below the surface ablation threshold, very efficient and specific material modification was observed after irradiation by a single or a few shots of mixed XUV/VIS-NIR radiation. We also report results on comprehensive characterization of ultrafast coherent X-ray beamline at Prague Asterix Laser System (PALS). The beamline is based on 1 kHz, table-top, high-order harmonic generation source capable to deliver fully coherent beam in the 30 nm spectral range. Ti:sapphire (810 nm, 1 kHz) laser pulses with a duration of 35 fs and energy 1.2 mJ have been focused into gas cell containing conversion medium (Ar). To achieve highly efficient HHG we will apply the technique of guided laser pulses. Source parameters were investigated.

We demonstrate a novel experimental method for efficient structural surface modification of various solids (PMMA, amorphous carbon) achieved by simultaneous action of XUV (21.6 nm), obtained from High-order Harmonic Generation (HHG), and Vis-NIR (410/820 nm) laser pulses. Although the fluence of each individual pulse was far below the surface ablation threshold, very efficient and specific material modification was observed after irradiation even by a single shot of mixed XUV/Vis-NIR radiation.

The polarization of high-harmonics from aligned N(2) molecules was measured by observing the visibility of spatial interference between two high-harmonics generated separately. The minimum visibility was observed at an angle of 60 degrees between the polarization of the harmonic generation laser field and the molecular orientation. In this case, the angular shift of harmonic polarization is 15 degrees from the molecular orientation. Our measurement of the visibility variation matches the theoretical prediction based on the harmonic field calculation for aligned N(2) molecules.

We report on the development of ultrafast coherent soft X-ray beamline at the Prague Asterix Laser System (PALS) Research Center intended for interdisciplinary applications such as ablation and controlled surface modification of solid materials for a micro/nano-pattering, soft X-ray interferometry and holography for surface probing with nanometric resolution, and improvement of focusing optics for soft X-ray beams. The beamline is based on 1 kHz, tabletop, high-order harmonic generation (HHG) source capable to deliver fully coherent, tunable beam in the 13 - 40 nm spectral range. Ti:sapphire (810 nm, 1 kHz) laser pulses with a duration of 35 fs and energy 1.5 mJ have been focused into a gas jet or gas cell containing conversion medium (Ar). To achieve highly efficient HHG we will apply the technique of guided laser pulses and the two-color laser field. Results on the optimization of HHG near 21 nm are presented. The beamline consists of a tandem of two vacuum chambers: one for the HHG source and its diagnostics, and second for the application experiments. After completion, access to this new installation will be opened to external users. This table-top system will be complementary to the existing, high energy (~10 mJ) Ne-like Zn soft X-ray laser at 21.2 nm developed at PALS. We will also present the first experimental results on the structural surface modifications of various solid materials (i.e., PMMA - poly(methyl methacrylate); amorphous carbon) caused by a few shot exposure to the focused HHG beam at 21.6 nm.

Currently, the market of multimedia information appliance based on Internet activated by the growth of both multimedia service and access of Internet augment the importance of TCP/IP protocol S/W which can provide the existing standalone embedded systems with Internet service. In this paper we analyze the architecture and function of TCP/IP module to depend on 4.4BSD OS (Operating System) runtime environment and propose the new method against TCP/IP module dependent on 4.4BSD OS runtime environment. And then we implement embedded OS for the network appliance that supports multitasking under its environment to use only physical memory in embedded system.

Materials processing utilizing ultrashort near-infrared (NIR) laser pulses with duration in the range of tens to hundreds of femtoseconds (1fs = 10 15 s) has attracted a great deal of interest in the scientific and industrial world recently. Unfortunately, a number of materials that often exhibit great technological and scientific importance are transparent in NIR, making it very difficult to process them by laser radiation in this spectral range. Here, we present a new method for the efficient structuring of the surface of materials by applying femtosecond NIR laser pulses simultaneously with a weak extreme ultraviolet (XUV) beam, which leads to very strong radiation-matter interaction, bringing a dramatic increase in the surface processing speed. A laser system providing 5mJ, 820nm, 32fs, 10Hz pulses was used to generate high-order harmonics with the strongest spectral line at 21nm and with a conversion efficiency of 5%. The two beams were focused on the samples by using an off-axis paraboloidal multilayer mirror. As an example, we present the results of the surface nanostructuring of thin films of amorphous carbon and poly(methyl methacrylate) deposited on bulk substrates. We discuss the physical mechanisms that lead to the laser-induced periodic surface structures when our method is used.

We have achieved very efficient high-harmonic generation in a two-color laser field using a long gas jet of He. With the optimization of laser parameters and target conditions, strong harmonics were produced at 2(2n+1)th orders in an orthogonally polarized two-color field. The strongest harmonic at the 38th order (21.6nm) reached an energy of 0.6μJ with a 6mm gas jet, giving a conversion efficiency as high as 2×10−4.

We demonstrate optical pulse trains with sub-100-attosecond high-frequency timing jitter from passively mode-locked, stretched-pulse fiber lasers by operating the lasers at the close-to-zero net cavity dispersion.

We demonstrate sub-100-attosecond timing jitter optical pulse trains generated from free-running, 77.6-MHz repetition-rate, mode-locked Er-fiber lasers. At -0.002(\pm0.001) ps2 net cavity dispersion, the rms timing jitter is 70 as (224 as) integrated from 10 kHz (1 kHz) to 38.8 MHz offset frequency, when measured by a 24-as-resolution balanced optical cross-correlator. To our knowledge, this result corresponds to the lowest rms timing jitter measured from any mode-locked fiber lasers so far. The measured result also agrees fairly well with the Namiki-Haus analytic model of quantum-limited timing jitter in stretched-pulse fiber lasers., 4 pages, 2 figures, to appear in Optics Letters