Abstract: We have studied functionalization of guide pattern with brush treatment. Especially, the effect of brush treatment on ordering of nanodots formed on the guide pattern was investigated. We used polydimethylsiloxane (PDMS) as brush modification to form self-assembled nanodots on the guide pattern using polystyrene (PS) - PDMS as block copolymer. The brush treatment using toluene solvent made guide patterns of the electron beam (EB) drawn resist behave like PDMS guide patterns and good ordering of the nanodots has been achieved. It was demonstrated that the brush treatment enabled the PDMS nanodots to be regularly located in the desired positions defined by the EB drawn guide patterns.
Abstract: In this work, we studied the fabrication of 12-nm-size nanodot pattern by self-assembly technique using high-etching-selectivity poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymers. The necessary etching duration for removing the very thin top PDMS layer is unexpectedly longer when the used molecular weight of PS-PDMS is 13.5-4.0 kg/mol (17.5 kg/mol total molecular weight) than that of 30.0-7.5 kg/mol (37.5 kg/mol total molecular weight). From this experimental result, it was clear that PS-PDMS with lower molecular weight forms thicker PDMS layer on the air/polymer interface of PS-PDMS film after microphase separation process. The 22-nm pitch of nanodot pattern by self-assembly holds the promise for the low-cost and high-throughput fabrication of 1.3 Tbit/inch2 storage device. Nanodot size of 12 nm also further enhances the quantum-dot effect in quantum-dot solar cell.
Abstract: We have studied on theoretical electron energy deposition in thin resist layer on Si substrate for electron beam lithography. We made Monte Carlo simulation to calculate the energy distribution and to consider formation of nanometer sized pattern regarding electron energy, resist thickness and resist type. The energy distribution in 100 nm-thick resist on Si substrate were calculated for small pattern. The calculations show that 4 nm-wide pattern will be formed when resist thickness is less than 30 nm. Furthermore, a negative resist is more suitable than positive resist by the estimation of a shape of the energy distribution.
Abstract: A wavelength-tunable laser is a powerful tool as light source for sensing and its research and development has been studied so far. In order to obtain a new tunable laser the authors have developed a tunable Er3+-doped fiber laser in Littman/Metcalf configuration, and incorporating a Galvano mirror, scanning of the lasing wavelength is demonstrated. For the emission range that a semiconductor-based light source hardly covers, a tunable Tm3+-Ho3+ fluoride fiber laser is also demonstrated.
Abstract: Light propagation in an optical waveguide fabricated by employing a dye-doped liquid crystal (DDLC) was observed. The propagation of a light signal in the waveguide was varied by irradiation with a control light whose wavelength was in the absorption band of the DDLC. By considering the photothermal effect of the DDLC, which enables the change of the refractive index due to temperature variation based on the absorption of light, we qualitatively explained the observed light propagation and demonstrated manipulation of the propagation.
Abstract: Proton beam writing (PBW) has attracted much attention recently as a next-generation micro-fabrication technology. It is a direct-drawing technique and does not need any masks to transfer micro-patterns to sample surfaces. In addition, the refractive index of a poly (methyl methacrylate) (PMMA) can be increased by proton-beam irradiation. In this study, we fabricated the first 1.5-μm-band single-mode, straight-line waveguides and Y-junction waveguides consisting of PMMA layers using the PBW technique.
Abstract: Quantitative shear wave velocity measurement inside the living tissue is a key technology in future qualitative diagnosis of breast tumor or liver diseases. We develop a novel shear wave velocity measurement system by using running wave number spectrum analysis of the complex displacement of the shear wave propagation excited by a single frequency. The velocity estimation method is demonstrated through the phantom experiments with the developed shear wave displacement measurement system. The validity of the measurement system is demonstrated by comparing with elastic wave simulation results. From the phantom experiments, it is shown that this method has high accuracy of velocity measurement even in the presence of large reflected waves.
Abstract: Local shear wave velocity measurements are effective to obtain tissue elasticity map. We have proposed novel wave number spectrum based shear wave velocity measurement system. However, the accuracy and resolution of this technique should be optimized and sophisticated in future clinical application for breast cancer diagnosis. We propose a simulator of RF signal in shear wave velocity measurement system which can consider arbitrary shear wave propagation. We demonstrate the usefulness of this simulator by experimental result. Moreover, accuracy and resolution of small object is discussed for breast cancer application.
Abstract: A method of inexpensive material tester based on the levitation mass method is improved. The tester is composed of an interferometer with Zeeman type two frequency He-Ne laser and a small pendulum as a substitute for a pneumatic linear bearing. As an example of a material tester using the pendulum, which evaluates the mechanical response of general objects against impact forces, is developed. The characteristics of the restoring force are measured under the free-swing condition. To demonstrate the performance of the developed instrument, the viscoelasticity of a gel block under an impact load is evaluated.
Abstract: The requirements for evaluating the mechanical characteristics of materials have increased in the various industrial, research and the applications such as materials testing. Therefore, the authors have proposed a method for measuring force acting a material using pendulum . In the Material tester, the mechanical characteristics of material against small force are measured by means of the pendulum mechanism based on the levitation mass method (LMM) [2,3,4].In the LMM, the Doppler shift frequency is measured for measuring the inertial force. The Doppler shift frequency of a laser beam reflected from the mass is accurately measured by using optical interferometer. The velocity, position, acceleration and inertia force of the mass are calculated from the measured time-varying Doppler shift frequency. Thus, the accurate measure of frequency makes that of force.