Takeyoshi Dohi

Scalable high-resolution integral videography autostereoscopic display with a seamless multiprojection system

We propose a scalable high-resolution autostereoscopic display that uses integral videography (IV) and a seamless multiprojection system. IV is an animated extension of integral photography (IP). Although IP and IV are ideal ways to display three-dimensional images, their spatial viewing resolution needs improvement; the pixel pitch of the display and the lens pitch are the main factors affecting IV image quality. We improved the quality by increasing the number and density of the pixels. Using multiple projectors, we create a scalable high-resolution image and project it onto a small screen using long-focal-length projection optics. To generate seamless IV images, we developed an image calibration method for geometric correction and color modulation. We also fabricated a lens array especially for the display device. Experiments were conducted with nine XGA projectors and nine PCs for parallel image rendering and displaying. A total of 2868 x 2150 pixels were displayed on a 241 mm x 181 mm (302.4 dots/in.) rear-projection screen. The lens pitch was 1.016 mm, corresponding to 12 pixels of the projected image. Measurement of the geometric accuracy of the reproduced IV images demonstrated that the spatial resolution of the display system matched that of the theoretical analysis.

Optimization Overlapping Ratio of Erbium: YAG Laser Irradiation for Less Thermal damaged Bone Cutting with Water Cooling

Lasers have the capability to remove or cut bone precisely without large reaction forces. However, surgeons have had many difficulties with using lasers during operations because of the thermal damage. In this paper, we propose an optimization the overlapping ratio, using water cooling; for the efficiency of laser bone ablations per unit time without thermal damages for operational application. A water-cooling Er: YAG laser (18.5 J/cm2, X=2.94ƒÊm, 20Hz, 200ƒÊs) using optical fiber was operated at 0.5-3.0mm/s moving velocities and repetitions. We focused specifically on the overlapping irradiated area and the interval time between the laser irradiations. Swine scapulae were ablated and its rate and performance were evaluated. The water-cooling Er: YAG laser obtained optimal ablation results when the moving velocity was set at 2.0mm/s; the overlapping ratio is 0.89, and the ablated area along the troughs per unit time was optimized to 0.50mm2/s. Carbonization was not evident at this velocity. Controlling of the lasers moving velocity, we can optimize the ablation ability to 0.50mm2/s at 2.0 mm/s. At this velocity, the mass removal efficiency was at 208 ƒÊg/J. This result was almost same with previously conducted results accomplished by free running without water cooling.