No abstract

We have investigated the properties of fluorocarbons as coolants for a high-power laser diode bar mounted on a funryu-jet heat sink. The thermal conductivities of fluorocarbons are about ten times lower than that of water, but they are less corrosive to the funryu copper heat sink and their boiling points may be higher than that of water. Since the cooling efficiency of such a high power laser diode (LD) bar may be a result of the dynamic viscosity, the heat capacity, the thermal resistance, and the boiling temperature of the coolant, we have compared two types of “Fluorinert”, 3M's FC77 and FC43, and water as coolants. Wavelength distributions along a 1 cm bar, operated under a 52 A driving current, are measured to be ±1.1 nm for FC77, ±2.1 nm for FC43 and ±0.6 nm for water. From their thermal and material characteristics given by 3M, the lower viscosity of FC77 is important for our funryu heat sink, which has a high flow resistance. A thermal resistance of 0.7°C/W is achieved at a flow rate of 1.0 L/min for FC77. FC77 is adopted as the coolant for CW 30 W operation and has operated continuously for over 800 h.

We propose a high-speed surface reconstruction from three-dimensional data through optical-digital hybrid processing.Surface images are currently reconstructed through digital processing, which takes a long time mainly because of the rotation and interpolation of the volume data. In the proposed system, slice images of threedimensional volume data are optically rotated and interpolated. In principle, one surface image can be obtained in the video rate when we use the same number of sets of optical processors as slices to be processed. Furthermore, this system could lead to a hybrid three-dimensional simulator; most operations such as rotation, cutting, digging holes, and peeling skins are interactively achieved at the video speed. Fundamental experiments are described that confirm the effectiveness of this method.

Three dimensional Computed Tomography ( CT ) with cone-beam geometry will take place of a conventional CT, because 3-D CT excels a conventional CT in terms of both data acquisition time and spatial resolution, particularly along the rotation axis. The small bone structures are reconstructed using magnified projections of the region of interest. This paper describes the solution for some problems in a practical use. Experimental results show 3-D CT will be feasible.

No abstract