Development of displacement- and frequency-noise-free interferometer in 3-D configuration for gravitational wave detection

The displacement- and frequency-noise-free interferometer (DFI) is a multiple laser interferometer array for gravitational wave detection free from both the displacement noise of optics and laser frequency noise. So far, partial experimental demonstrations of DFI have been done in 2-D table top experiments. In this paper, we report the complete demonstration of a 3-D DFI. The DFI consists of four Mach-Zehnder interferometers with four mirrors and two beamsplitters. The displacement noises both of mirrors and beamsplitters were suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational wave was successfully confirmed using multiple electro-optic modulators and computing methods

Ultrasonic stent motor

The purpose of this study is to develop a stent motor for medical blood vessel treatment. The stent motor is a movable stent. It has functions of removing plaque and expanding blood vessels. It consists of two parts; ultrasonic receivers and vibration transmitting coil (stator). In this study, the authors have focused to the vibration analysis of the receiver. In the first design stage, the authors have evaluated resonant phenomenon using finite element method. When driving it in water, the resonant frequency of the air use is shifted due to mass effect of water around the receiver. The frequency analysis of the receiver shows that extremely high precision of dimensions is required because the resonant frequency in water depends not only the size but also the amplitude of the vibration. It is very difficult to design an optimal receiver resonating in water. In order to solve this problem, the authors have tried a new receiver with wide plate receiving ultrasound effectively and requiring no resonant. The authors have succeeded in driving this type of motor in water

Waterproof ultrasonic motor

The authors have been making a multi degree of freedom piezoelectric actuator that has Translational and Rotational motions in one joint (TR motor). Because the motor has the advantages such as simple structure and excellent controllability, it has high potentials for wide use in non-industrial applications. The authors will apply it to outdoor use, especially, use in water. The authors have applied insulating process to the piezoelectric element for waterproof and designed an optimal shape of it for driving in water to show driving TR motor in water successfully

All-order evaluation of weak measurements: --- The cases of an operator A{\bf A} which satisfies the property A2=1{\bf A}^{2}=1 ---

Some exact formulae of the expectation values and probability densities in a weak measurement for an operator ${\bf A}$ which satisfies the property ${\bf A}^{2}=1$ are derived. These formulae include all-order effects of the unitary evolution due to the von-Neumann interaction. These are valid not only in the weak measurement regime but also in the strong measurement regime and tell us the connection between these two regime. Using these formulae, arguments of the optimization of the signal amplification and the signal to noise ratio are developed in two typical experimental setups.Comment: 17 pages, 10 figures (v1); Fig.3 and some typos are corrected (v2); Comments and references are added and some typos are corrected (v3

Demonstration of displacement-noise-free interferometry using bi-directional Mach–Zehnder interferometers

We have demonstrated displacement- and frequency-noise-free laser interferometry (DFI) by partially implementing a recently proposed optical configuration using bi-directional Mach–Zehnder interferometers (MZIs). This partial implementation, the minimum necessary to be called DFI, has confirmed the essential feature of DFI: the combination of two MZI signals can be carried out in a way that cancels the displacement noise of the mirrors and beam splitters while maintaining gravitational-wave signals. The attained maximum displacement noise suppression was 45 dB

Axisymmetric polydimethysiloxane microchannels for in vitro hemodynamic studies

The current microdevices used for biomedical research are often manufactured using microelectromechanical systems (MEMS) technology. Although it is possible to fabricate precise and reproducible rectangular microchannels using soft lithography techniques, this kind of geometry may not reflect the actual physiology of the microcirculation. Here, we present a simple method to fabricate circular polydimethysiloxane (PDMS) microchannels aiming to mimic an in vivo microvascular environment and suitable for state-of-the-art microscale flow visualization techniques, such as confocal µPIV/PTV. By using a confocal µPTV system individual red blood cells (RBCs) were successfully tracked trough a 75 µm circular PDMS microchannel. The results show that RBC lateral dispersion increases with the volume fraction of RBCs in the solution, i.e. with the hematocrit

The experimental plan of displacement- and frequency-noise free laser interferometer

We present the partial demonstration of displacement- and laser-noise free interferometer (DFI) and the next experimental plan to examine the complete configuration. A part of the full implementation of DFI has been demonstrated to confirm the cancellation of beamsplitter displacements. The displacements were suppressed by about two orders of magnitude. The aim of the next experiment is to operate the system and to confirm the cancellation of all displacement noises, while the gravitational wave (GW) signals survive. The optical displacements will be simulated by electro-optic modulators (EOM). To simulate the GW contribution to laser lights, we will use multiple EOMs

Development of deep-sea drone by spherical ultrasonic motor

The world ocean occupies 70 % on the earth and the average sea depth is about 4,000 m. More than 80 percent of it has not been investigated precisely and the bottom shape of the sea has not been mapped. When doing resource-searching in the future, the precise maps must be required. So, the authors have developed a drone movable around 4,000 m deep sea to measure the bottom of the ocean. It is based on spheres, which includes cameras, batteries, some sensors and controllers. It can rotate a spherical rotor sensing widely to obtain the information about the bottom of the sea. At the first step of the research, the authors have made basic experiments of the motor’s performance in water. The authors have obtained the excellent results in maneuverability, temperature durability, and shock resistance of the motor

Intravascular stent motor powered by ultrasonic irradiation

We have developed a stent motor that can move in the blood vessel by applying the technique of the ultrasonic motor. First, we have designed a horn to provide ultrasonic energy to the stent from outside of human body. Second, we have also designed a stent motor that consists of two parts; a stator and receivers. The receiver unit obtains the ultrasonic wave from outside. The stator is the coil shape and it can move smoothly in intravascular. Finally, we have made experiments by the horn and stent motor. We have succeeded in driving the stent motor back and forth in the water

Theory of radiation trapping by the accelerating solitons in optical fibers

We present a theory describing trapping of the normally dispersive radiation by the Raman solitons in optical fibers. Frequency of the radiation component is continuously blue shifting, while the soliton is red shifting. Underlying physics of the trapping effect is in the existence of the inertial gravity-like force acting on light in the accelerating frame of reference. We present analytical calculations of the rate of the opposing frequency shifts of the soliton and trapped radiation and find it to be greater than the rate of the red shift of the bare Raman soliton. Our findings are essential for understanding of the continuous shift of the high frequency edge of the supercontinuum spectra generated in photonic crystal fibers towards higher frequencies.Comment: Several misprints in text and formulas corrected. 10 pages, 9 figures, submitted to Phys. Rev.