Tomoyu Yamashita

Bio: Tomoyu Yamashita is an academic researcher from Advantest. The author has contributed to research in topics: Terahertz radiation & Detector. The author has an hindex of 5, co-authored 18 publications receiving 53 citations.

3D Imaging and analysis system using terahertz waves

Abstract: We have developed the “3D Imaging Analysis System” that uses terahertz waves, the world's first such system for practical applications. This system has an unprecedented capability for nondestructive three-dimensional spectroscopic analysis of the spatial distribution of constituents.

3D Spectroscopic computed tomography imaging using terahertz waves

Abstract: We have developed a three-dimensional spectroscopic imaging system that uses terahertz waves and is based on transmission computed tomography. Using this system, we demonstrate transmission three-dimensional computed tomography imaging of high refractive index objects, with identification of chemical components, by analyzing spectroscopic information.

Electromagnetic wave measuring apparatus, measuring method, program and recording medium

Abstract: An electromagnetic wave measurement device includes an electromagnetic wave outputter that outputs an electromagnetic wave having a frequency equal to or more than 001 THz and equal to or less than 100 THz toward a device under test An electromagnetic wave detector detects the electromagnetic wave which has transmitted through the device under test A relative position changer changes a relative position of an intersection of an optical path of the electromagnetic wave transmitting through the device under test and the device under test, with respect to the device under test, so that the intersection is at a predetermined relative position due to the refraction of the electromagnetic wave by the device under test A characteristic value deriver derives a characteristic value of the electromagnetic wave based on a detection result of the electromagnetic wave detector, the characteristic value being associated with the predetermined relative position

Polarization mode dispersion measuring device, method, recording medium

Abstract: A polarization mode dispersion measuring device reduced in time required to measure polarization mode dispersion τ PMD . A polarization controller ( 12 ) allows a first (second) incident light to apply a synthetic incident light to an object to be measured ( 30 ) in line with a p-polarization axis (s-polarization axis) in a polarization separator ( 16 ). Accordingly, the phase shift equivalent value (optical angle frequency differentiation) and amplitude equivalent value (square value) of a first incident light component (second incident light component) in an output from the polarization separator ( 16 ) measured by a first measuring unit ( 20 a ) (second measuring unit ( 20 b )) are respectively the phase shift equivalent value and amplitude equivalent value of a first column T 11 , T 21 (second column T 12 , T 22 ) when the transfer function matrix of the object to be measured ( 30 ) is a 2×2 matrix to thereby allow a control unit ( 2 ) to determine the polarization mode dispersion r PMD of the object to be measured ( 30 ). Since there is no need of switching the orientation setting of light output from the polarization controller ( 12 ) with the setting left fixed, time required to measure polarization mode dispersion τ PMD can be shortened.

Electromagnetic wave measuring device, measuring method, program, and recording medium

Abstract: According to the present invention, the CT is carried out based on parameters other than the absorption rate. An electromagnetic wave measurement device includes an electromagnetic wave output device 2 which outputs an electromagnetic wave at a frequency equal to or more than 0.01 [THz] and equal to or less than 100 [THz] toward a device under test 1, an electromagnetic wave detector 4 which detects the electromagnetic wave which has transmitted through the device under test 1, a relative position changing unit 6 which changes a relative position of an intersection 100 at which an optical path of the electromagnetic wave transmitting through the device under test 1 and the device under test 1 intersect with respect to the device under test 1, a phase deriving unit 12 which derives, based on a detected result by the electromagnetic wave detector 4, a phase in the frequency domain of the electromagnetic wave which has transmitted through the device under test 1, a sinogram deriving unit 16 which derives a sinogram based on a derived result by the phase deriving unit 12, and a cross sectional image deriving unit 18 that derives, based on the sinogram, an image of a cross section of the device under test 1 including a trajectory of the intersection 100.

Review of Terahertz Tomography Techniques

Abstract: Terahertz and millimeter waves penetrate various dielectric materials, including plastics, ceramics, crystals, and concrete, allowing terahertz transmission and reflection images to be considered as a new imaging tool complementary to X-Ray or Infrared. Terahertz imaging is a well-established technique in various laboratory and industrial applications. However, these images are often two-dimensional. Three-dimensional, transmission-mode imaging is limited to thin samples, due to the absorption of the sample accumulated in the propagation direction. A tomographic imaging procedure can be used to acquire and to render three-dimensional images in the terahertz frequency range, as in the optical, infrared or X-ray regions of the electromagnetic spectrum. In this paper, after a brief introduction to two dimensional millimeter waves and terahertz imaging we establish the principles of tomography for Terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR) and time-of-flight (TOF) terahertz tomography. For each technique, we present advantages, drawbacks and limitations for imaging the internal structure of an object.

Terahertz imaging based on optical coherence tomography [Invited]

Abstract: Three-dimensional (3D) terahertz (THz) imaging or THz tomography has recently proven to be useful for nondestructive testing of industrial materials and structures In place of previous imaging techniques such as THz pulsed/continuous-wave radar and THz computed tomography, we propose a THz optical coherence tomography using photonics- and electronics-based THz sources, and demonstrate thickness measurement and tomographic imaging in frequency regions from 400 to 800 GHz

Terahertz tomographic imaging of XVIIIth Dynasty Egyptian sealed pottery

Abstract: A monochromatic millimeter-wave imaging system coupled with an infrared temperature sensor has been used to investigate historic objects preserved at the Museum of Aquitaine (France). In particular, two-dimensional and three-dimensional analyses have been performed in order to reveal the internal structure of nearly 3500-year-old sealed Egyptian jars.

Methods and apparatus for electromagnetic signal polarimetry sensing

Abstract: A system and method of identifying changes utilizing radio frequency polarization includes receiving a reflected and/or transmitted polarized radio frequency signal at a receiver, filtering, amplifying and conditioning the received signal, converting the received signal from an analog format to a digital format, processing the digital signal to elicit a polarization mode dispersion feature of the received signal, and comparing the polarization mode dispersion features to a known calibration to detect a change in a characteristic of the target object.