41 citations · 142 across the 14 of their papers we have counts for
14 papers
Temperature dependence of broadband seismometer sensitivity
Tomofumi Shimoda, Wataru Kokuyama, Hideaki Nozato
Broadband seismometers are widely used in global observation networks deployed for geophysics research. Recently, the calibration of their sensitivity has become an important facto…
Accurate laboratory testing of low-frequency triaxial vibration sensors under various environmental conditions
Tomofumi Shimoda, Wataru Kokuyama, Hideaki Nozato
Triaxial vibration sensor are widely used used in various application. Recently, low-cost sensors based on micro electro mechanical system (MEMS) technology are also becoming more…
Optical sound pressure measurement using Fabry-Pérot cavity for primary acoustic standards
Koto Hirano, Wataru Kokuyama, Hajime Inaba +5
Optical sound pressure measurement is a promising technology to establish primary acoustic standards without reliance on specific types of microphones. We developed a precision opt…
Measurement of the intrinsic sensitivity for a single-ended accelerometer without the influence of the mounting condition
Tomofumi Shimoda, Wataru Kokuyama, Hideaki Nozato
The calibration technique for accelerometers has been internationally developed for up to 20 kHz to ensure the reliability of vibration measurement. However, it has been establishe…
Primary accelerometer calibration with two-axis automatic positioning stage
Wataru Kokuyama, Tomofumi Shimoda, Hideaki Nozato
In this study, we developed an automated, multipoint primary accelerometer calibration system using a two-axis positioning stage and a heterodyne laser interferometer. The proposed…
Precise sinusoidal signal extraction from noisy waveform in vibration calibration
Tomofumi Shimoda, Wataru Kokuyama, Hideaki Nozato
Precise extraction of sinusoidal vibration parameters is essential for the dynamic calibration of vibration sensors, such as accelerometers. However, several standard methods have…
Phase meter based on zero-crossing counting of digitized signals
Wataru Kokuyama, Hideaki Nozato, Thomas R. Schibli
We developed a compact and easy-to-use phase meter based on a zero-crossing counting algorithm for digitized signals. Owing to the algorithm, the phase meter has low-noise and wide…
Simple digital phase-measuring algorithm for low-noise heterodyne interferometry
Wataru Kokuyama, Hideaki Nozato, Akihiro Ohta +1
We present a digital algorithm for measuring the phase difference between two sinusoidal signals that combines the modified fringe-counting method with two-sample zero crossing to…
Higher order test of Lorentz invariance with an optical ring cavity
Yuta Michimura, Jake Guscott, Matthew Mewes +5
We have developed an apparatus to search for the higher-order Lorentz violation in photons by measuring the resonant frequency difference between two counterpropagating directions…
Search for a Stochastic Gravitational-wave Background using a pair of Torsion-bar Antennas
Ayaka Shoda, Masaki Ando, Koji Ishidoshiro +4
We have set a new upper limit on the stochastic gravitational wave background (SGWB) using two prototype Torsion-bar Antennas (TOBAs). TOBA is a low-frequency gravitational-wave de…
Testing Lorentz Invariance with a Double-Pass Optical Ring Cavity
Yuta Michimura, Nobuyuki Matsumoto, Noriaki Ohmae +4
We have developed an apparatus to test Lorentz invariance in the photon sector by measuring the resonant frequency difference between two counterpropagating directions of an asymme…
New Limit on Lorentz Violation Using a Double-Pass Optical Ring Cavity
Yuta Michimura, Nobuyuki Matsumoto, Noriaki Ohmae +4
A search for Lorentz violation in electrodynamics was performed by measuring the resonant frequency difference between two counterpropagating directions of an optical ring cavity.…
Upper Limit on Gravitational Wave Backgrounds at 0.2 Hz with Torsion-bar Antenna
Koji Ishidoshiro, Masaki Ando, Akiteru Takamori +7
We present the first upper limit on gravitational wave (GW) backgrounds at an unexplored frequency of 0.2 Hz using a torsion-bar antenna (TOBA). A TOBA was proposed to search for l…
The boiling suppression of liquid nitrogen
S. Takayoshi, W. Kokuyama, Hiroshi Fukuyama
When He gas is injected from room temperature into boiling liquid N, boiling is suppressed, leaving liquid surface flat like a mirror. Although the qualitative explanation fo…