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<p>This thesis presents new methods for finding optimal and near-optimal constant weight binary codes with distance d and weight w such that d=2(w-1). These methods have led to the discovery of a number of new codes which are being submitted for publication. Improvements in methods for generating lexicographic codes are also discussed, with suggestions for further research in this area.</p>

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One -dimensional infrared speckle scans of Ross 614 AB were recorded at a wavelength of 2.2μm. For each scan an estimate of the instantaneous quality of the seeing was calculated and the scan was binned accordingly. The three bins corresponding to the three best seeing conditions were further processed by applying the shift -and -add algorithm to the set of images contained within each bin, thereby generating three shift- and -add images with differing shift -and -add point -spread- functions. After windowing the shift -and -add images (using edge -extension) to reduce the effect of contamination, we have obtained parameters corresponding to the separation and brightness ratio of a two component model of the double star Ross 614 AB by deconvolving the three shift -and -add images with the aid of the zero-and -add technique. Least squares analysis on the positions of the clusters of zeros found from zero- and -add yields a separation of 1.04 arcseconds and a brightness ratio of 4.3 for the binary system at this wavelength. An extension of the processing, which takes explicit account of the nonlinear motion of the scanning mechanism gives improved estimates of 1.04 arcseconds and 3.9 for the separation and brightness ratio, respectively.