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Tracking position and orientation accurately and precisely is important in effective virtual reality systems. Large volume trackers are necessary to build effective augmented reality systems. A new approach to large-volume six-degree-of-freedom tracking is presented. The approach uses ultrasonic measurement technology and cellular deployment to achieve a relatively low-cost large-volume tracker. >

We describe a 2-/spl mu/m diode-pumped, room temperature Ho:Tm:YLF laser and end-pumped amplifier system. The Ho:Tm:YLF oscillator utilized a multiple folded resonator with eight mirrors. A Q-switched output energy of 109 mJ pulse was obtained at 6 Hz. This new design makes the laser a smaller size, which can be used in space application. The effects of the laser operating temperature, thermal focusing and resonator structure rigidity on the performance of the laser were also investigated. In order to increase the laser system energy and efficiency, an end-pumped Ho:Tm:YLF disk amplifier was designed. Preliminary results showed that the efficiency of this laser amplifier could be better than 3% during Q-switch operation, a factor of three increase over side-pumped amplifier configuration. The laser system performance and its potential use for remote sensing of wind are presented.

A narrow-linewidth all-solid-state laser system of low divergence with appreciable pulse-energy in the eyesafe region is required as a transmitter for the coherent wind lidar measurements from ground, air, and space-borne platform. Research efforts at NASA Langley Research Center (LaRC) were initiated to identify the laser material for optimum gain near eyesafe wavelength of 2-/spl mu/m. The Ho:Tm:YLF crystal, operating at 2.05 /spl mu/m, was selected as the laser gain medium based on a theoretical model developed at NASA/LaRC.

In many applications one is concerned with the approximation of functions from a finite set of given data sites with associated function values. We describe a construction of a hierarchy of triangulations which approximate the given data at varying levels of detail. Intermediate triangulations can be associated with a particular level of the hierarchy by considering their approximation errors. This paper presents a new data-dependent triangulation scheme for multi-valued scattered data in the plane. We perform piecewise linear approximation based on data-dependent triangulations. Our scheme preserves edges (discontinuities) that might exist in a given data set by placing vertices close to edges. We start with a coarse, data-dependent triangulation of the convex hull of the given data sites and subdivide triangles until the error of the piecewise linear approximation implied by a triangulation is smaller than some tolerance.