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Biomedical subjects

Yoshimasa Kawata

Publications and source records attributed to Yoshimasa Kawata.

7 recordsLinked to original sources
PubMed2006

Fabrication of multilayered photochromic memory media using pressure-sensitive adhesives.

We fabricated a multilayered medium by a laminating process with pressure-sensitive adhesives. It was possible to reduce the thickness variations of both photosensitive layers and transparent layers by applying laminating films. This method is easy to use to pile up many layers for a multilayered medium. We fabricated twenty recording layers and demonstrated the capability to record with significant reading results. The recorded data in each layer were read out without crosstalk. We evaluated the signal-to-noise ratio and crosstalk between neighboring layers. It was found that the signal-to-noise ratio of a multilayered medium was higher than 50 dB.

Journal Article↗
PubMed2006

Confocal nonlinear optical microscopy for high-resolution measurement of absorptive objects.

We demonstrate a new scheme to enhance the spatial resolution of a confocal optical microscope. Our scheme improves the spatial resolution in the direction of the optical axis. The confocal optical microscope, by use of a four-wave mixing geometry, can obtain optical information about weakly absorptive objects with organic dyes. Owing to the third-order nonlinear dependence of absorptive objects, the optical signal is confined to the focal region of the focusing incident beam.

Journal Article↗
PubMed2005

Light propagation in a multilayered medium for three-dimensional optical memory.

We report on the optimization of film thicknesses in a multilayered medium to increase readout signal intensity. The multilayered medium consists of a stack of photosensitive and transparent films, arranged alternately. The thicknesses of the photosensitive and transparent films in the multilayered medium were optimized for a reflection confocal system to read out data by analyzing the propagation of light focused into a multilayered medium.

Journal Article↗
PubMed2004

Frequency response characteristics of a birefringent lens with off-axis aberrations.

We report the frequency response characteristics of an optical system consisting of a lens made of a uniaxial birefringent crystal sandwiched between two linear polarizers; the lens has prespecified off-axis aberrations such as primary astigmatism and primary coma. An analytical expression is obtained for the optical transfer function of the proposed system by use of the autocorrelation of the pupil function over the lens aperture. Some specific cases are computed and illustrated graphically. It has been shown that the proposed system has imaging characteristics distinctly different from those of an ordinary glass lens, and these may be advantageous for better balancing of aberrations in conventional imaging systems.

Journal Article↗
PubMedDate not supplied

Localization of surface plasmon by using a metal-coated axicon prism.

We present the localization of surface plasmon using a metal-coated axicon prism and its application to fluorescence scanning microscopy. The cone angle of the axicon prism is designed such that a plane wave incident on the prism can excite surface plasmon on the side surface of the prism. Since the surface plasmon propagates toward the apex of the prism, an extremely high enhancement of the electric field is expected. The proposed technique can overcome the trade-offbetween the field-enhancement factor of surface plasmon and the resolution limit due to the propagation of surface plasmon. The experimental result obtained with the localized surface plasmon is also demonstrated.

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