Masayuki Otsuka

Magnetic resonance imaging apparatus having vibration damping means on gradient coil

A magnetic resonance imaging apparatus includes a magnet for generating a static magnetic field, a gradient coil for generating a gradient magnetic field in a measurement space, and a vibration damping means which includes a container and granular material disposed in the container. The vibration damping means is installed with a supporting bolt between the gradient coil and a supporting means. Since the gradient coil is supported at a constant position without any vibration and deformation, the magnetic resonance imaging apparatus generates an accurate image signal without any acoustic noise.

5331281 Gradient magnetic field generating coil assembly of magnetic resonance imaging apparatus

A gradient magnetic field-generating coil assembly of MR imaging apparatus has a cylindrical core member for carrying coil windings that is divided into at least two cores at a central portion of a magnet bore, a gap is set up between the two cores at the central portion of the magnet bore and each core is provided at its opposite ends with parts for fixing it to the magnet, whereby the natural vibration frequency of the core can be deviated from an exciting force frequency and sound prevailing in the outside of the core and sound in the inside can be brought into interference with each other to thereby suppress vibration of the cores at the central portion of the magnet bore and reduce noise.

Installation of electric field electron beam blanker in high-resolution transmission electron microscopy

We have newly installed an electric field electron beam blanker in a transmission electron microscopy, which chops an electron beam very quickly without the effect of hysteresis. The electric field, which is generated by the electron beam blanker, deflects the electron beam, and the electron beam is intercepted by an aperture. The response time of the beam blanker is 50μs. Therefore, a very short pulsed electron beam enables a charge-coupled device camera to directly expose an electron beam spot or diffraction pattern. Moreover, we measured the response of a deflector coil, which is usually used as an electron beam blanker, using our electron beam blanker. Our beam blanker will become a key component in a computer-assisted minimal dose system, which enables us to reduce the electron dose of the sample.