Showing papers by "Satoshi Kawata published in 1996"
TL;DR: Experiments in which Mie-scattering particles were optically driven in the evanescent field that is generated in a channeled waveguide found polystyrene latex spheres with diameters of 1-5 microm laterally trapped and longitudinally driven along the direction of the waveguide channel.
Abstract: We report a series of experiments in which Mie-scattering particles were optically driven in the evanescent field that is generated in a channeled waveguide. Polystyrene latex spheres with diameters of 1-5 microm were laterally trapped within the evanescent field, which was produced by a cw laser beam incident upon the waveguide and then longitudinally driven along the direction of the waveguide channel at speeds of as much as 14 microm/s. Metallic spheres of gold (0.5-microm diameter) and platinum (1-microm diameter) were also laterally trapped and longitudinally moved along the waveguide channel.
283 citations
01 Sep 1996
TL;DR: In this paper, a point in a 3D volume of UV photopolymerizing resin is photopolymersized through two-photon absorption process, which greatly improves the depth resolution.
Abstract: Fabrication technology for three-dimensional microstructures with submicrometer accuracy has been needed in the fields of modern optics, such as micro mechanical system driven with photon pressure[1, 2] and laser-trapping near-filed optical microscopy[3]. However, the present accuracy with stereolithography[4] is not yet satisfactory to this purpose. Moreover, it is not so flexible to make a three- dimensional structure with the present technique. In this paper, we propose a new microfabrication method in which a point in three-dimensional volume of UV photopolymerizing resin is photopolymerized through two-photon absorption process. The microfabrication with two-photon absorption drastically improves the depth resolution due to a nonlinearlity between the power of the irradiation and that of the absorption[5].
237 citations
TL;DR: A technique that utilizes surface-plasmon resonance to intensify the fluorescence produced by multiphoton excitation by enhancing the electric field initially generated by the excitation laser light is demonstrated.
Abstract: We demonstrate a technique that utilizes surface-plasmon resonance to intensify the fluorescence produced by multiphoton excitation. By enhancing the electric field initially generated by the excitation laser light, the presence of plasmon resonance introduces a gain 90 times higher in the experimentally observed fluorescence intensity than that produced from total internal reflection fluorescence. We also analyze the enhancement efficacy of surface-plasmon resonance as a function of the excitation wavelength.
106 citations
TL;DR: In this paper, the authors analyzed how the interaction between the probe and the field near the sample surface affects the characteristics of the images produced by a near-field scanning optical microscope.
92 citations
TL;DR: The three-dimensional refractive-index distribution that is induced locally when a laser beam is focused onto a very small region in a photorefractive crystal is analyzed and a good agreement was obtained between experimental results and the calculated phase-contrast images when the characteristics of the imaging system are taken into account.
Abstract: We analyze the three-dimensional refractive-index distribution that is induced locally when a laser beam is focused onto a very small region in a photorefractive crystal. The formation of the index distribution is deduced from the temporal behavior of the electron density distribution in the crystal under non-steady-state conditions. The density distribution is computed by the use of a set of the recurrence relations that was derived from Kukhtarev's equations, which describe the transport of electrons in time. In particular, we calculated the index distribution formed in Fe-doped LiNbO(3) crystals. To verify the validity of our analysis, we read, by using a phase-contrast microscope, refractive-index dots that were recorded in Fe-doped LiNbO(3) crystals. A good agreement was obtained between experimental results and the calculated phase-contrast images when the characteristics of the imaging system are taken into account. We also found that the induced index change is largest when the c axis of the LiNbO(3) crystal is oriented parallel to the polarization direction of the reading beam. Under this optimal condition, we succeeded in recording up to 10 layers of readable data in a LiNbO(3) crystal.
73 citations
TL;DR: Some Fe(II) ferrocenylacetylide complexes were prepared by photolysis of the corresponding carbonyl complexes in the presence of diphosphine as discussed by the authors.
61 citations
TL;DR: A threedimensional transfer function approach is used to show that one cannot use a ref lection confocal system to read a photopolymer-based memory, and that this has serious implications for the choice of readout system.
Abstract: The method of recording data in a volume memory determines the spatial frequency content. We use a threedimensional transfer function approach to show that this has serious implications for the choice of readout system. In particular, one cannot use a ref lection confocal system to read a photopolymer-based memory. A solution to this problem is proposed.
58 citations
TL;DR: A transmission differential phase-contrast microscope with a split detector is used as a readout system for a multilayered three-dimensional optical memory that shows that the spatial bandwidth of the system is the same as that of a conventional microscope with incoherent illumination but with much improved contrast.
Abstract: A transmission differential phase-contrast microscope with a split detector is used as a readout system for a multilayered three-dimensional optical memory. The system is applicable to data recorded as refractive-index changes. The system is compact and easy to use. The three-dimensional optical transfer function for the system is derived. This shows that the spatial bandwidth of the system is the same as that of a conventional microscope with incoherent illumination but with much improved contrast. Six layers of information are recorded in a photopolymer and are read out with little cross talk and high contrast.
45 citations
TL;DR: In this paper, the steady-state fluorescence spectra of poly(N-vinylcarbazole) (PVCz) with various molecular weights in tetrahydrofuran solution were examined.
42 citations
TL;DR: In this paper, the geometrical limits of the recording density that can be attained in three-dimensional optical memory systems that employ the multilayered bit-recording method and the angularly multiplexed holographic recording method were compared.
Abstract: We compare the geometrical limits of the recording density that can be attained in three-dimensional optical memory systems that employ the multilayered bit-recording method and the angularly multiplexed holographic recording method. Both recording methods have the potential to overcome the recording density limitations in current optical storage systems. Using the Ewald sphere construction, we analyze the lateral and longitudinal bandwidths for each recording method. The respective recording densities of the two methods are also derived directly in the space domain and compared with each other. With the bit-recording method we found that the memory density increases inversely with the f-number of the recording lens. On the other hand, the density that can be achieved using holographic recording first increases with the f-number values, attains a maximum, and then decreases at larger f-number values. This implies that the bit-recording method yields larger memory densities when lenses of smaller f-numbers are used in the optical system.
34 citations
TL;DR: To the authors' knowledge, this is the first successful demonstration of the selective optical erasure of the photochromic effect in a BSO crystal.
Abstract: A read-and-write, randomly accessible, multilayered optical memory with a Bi(12) SiO(20) crystal as the medium is demonstrated. Data are recorded in the crystal as an absorption change that is due to the photochromic effect. These data are successfully recorded, read, and selectively erased in five layers in the crystal. The axial-separation distance between neighboring layers is 30 μm, and the lateral distance between bits is 5 μm. Selective bit erasure of the data is accomplished by illumination of the recorded bit datum with He-Ne laser light. To our knowledge, this is the first successful demonstration of the selective optical erasure of the photochromic effect in a BSO crystal.
TL;DR: A 4Pi confocal system that incorporates a phase-conjugate mirror into the system to solve the alignment problem and automatically correct the spherical aberration associated with the conventional 4Pi Confocal system when observing a thick sample is proposed.
Abstract: We propose a 4Pi confocal system that incorporates a phase-conjugate mirror into the system to solve the alignment problem and automatically correct the spherical aberration associated with the conventional 4Pi confocal system when observing a thick sample. The proposed system is experimentally verified by use of cerium-doped barium titanate crystal as the phase-conjugate mirror. The full width of the central peak is ∼0.15 μm. We also theoretically verify the advantage of automatic correction of the spherical aberration by calculating the intensity distribution at the focal spot.
TL;DR: In this paper, a semiconductor laser confocal microscope is developed for measuring the optical thickness of thin transparent samples at high spatial resolution, which is computed from the amount of axial displacement that the mirror must be given to regain maximum feedback.
Abstract: A semiconductor laser confocal microscope is developed for measuring the optical thickness of thin transparent samples at high spatial resolution. The optical sectioning capability of a confocal microscope, and the sensitivity of the laser output to optical feedback, are both utilized to detect the presence of a nonabsorbing sample in the path of the probe beam that is initially focused onto a plane mirror. The index mismatch at the sample interface defocuses the beam away from the mirror and reduces the amount of optical feedback. The optical thickness is computed from the amount of axial displacement that the mirror must be given to regain maximum feedback. The laser power output is monitored using the monitor photodiode in the laser package. When the geometrical thickness of the sample is known a priori, the technique can be used to measure its refractive index and vice versa. The smallest and largest measurable sample thickness are determined by the sharpness of the axial intensity response of the mic...
TL;DR: In this paper, a phase conjugation mirror is used instead of the plane or concave mirror commonly employed in a conventional double-pass optical design, and a system using a BaTiO3 crystal is developed to verify the effectiveness of the proposed principle.
Abstract: A new double-pass confocal absorption microscope is proposed where a phase conjugation mirror is used instead of the plane or concave mirror commonly employed in a conventional double-pass optical design. A practical system using a BaTiO3 crystal is developed to verify the effectiveness of the proposed principle. Using a diatom material as sample, a comparison is made between the image produced by our new microscope with those obtained using a conventional double-pass microscope, and a single-pass non-confocal microscope.
TL;DR: In this paper, the authors proposed a method to visualize a phase object using a locally-controllable image amplification scheme based on two-wave coupling in a bismuth silicon oxide (Bi12SiO20, or BSO) crystal.
Abstract: We propose a method to visualize a phase object using a locally-controllable image amplification scheme we developed earlier which is based on two-wave coupling in a bismuth silicon oxide (Bi12SiO20, or BSO) crystal. In this method the BSO crystal is used as a phase plate in the configuration of Zernike’s phase contrast imaging system. The principle of the phase-visualization with two-wave coupling is presented. An experimental result to verify the proposed method is shown.
01 Sep 1996
TL;DR: In this article, the minimum size of the focused spot size formed by photons is as wide as a half of the wavelength due to the diffraction limit, which is helpful for the academic studies on the dynamics of single atom, single molecule and single cell and its engineering applications to manipulate molecules, cells, and mesoscopic devices in nanometric dimensions.
Abstract: For the future progress of the modern advanced sciences and engineering such as biological science, material science, quantum physics, and semiconductor and microelectronics industries, the nanometric-scale technology for manipulation, fabrication, control, observation, and analysis for ultra-small structures is required. If photons could interact with small and fine structures within the extent of subwavelength area, it would be helpful for the academic studies on the dynamics of single atom, single molecule and single cell and its engineering applications to the manipulation of molecules, cells, and mesoscopic devices in nanometric dimensions. However, as is well known, the minimum size of the focused spot size formed by photons is as wide as a half of the wavelength due to the diffraction limit.