Photometry and astrometry performed with charge coupled devices (CCDs) at the focal planes of large telescopes are indispensable tools of modern observational cosmology, astrophysics and astronomy. In the modern era of precision cosmology, variations in the sub-pixel sensitivity and spectral response of CCDs can affect the science yield of observations and must be characterized. Unfortunately, there have been very few studies to measure the sub-pixel response variations of CCDs, particularly in the context of observational cosmology. It is the aim of this thesis to perform the first measurement of the photometric and astrometric fidelity of high-resistivity, p-channel CCDs. These devices have been selected for major upcoming observational cosmology missions such as the space-based Supernova Acceleration Probe satellite (SNAP) and the ground-based Dark Energy Survey. An experimental study has been performed to make detailed measurements of the intrapixel response variations of these devices at a precision exceeding 2%, which is the level of precision required for the missions mentioned above. A 300 mum thick, 10.5 mum pixel pitch, 1.4kx1.4k format, high-resistivity, p-channel CCD operated fully depleted was illuminated by a 1.3 mum pinhole projector. The illuminated spot was moved in sub-pixel steps through various patterns to measure several properties of the device including the lateral charge diffusion, the intrapixel sensitivity variations, the effective diffusion near the edge of the device active region where electric field lines in the device may diverge, to test the photometric performance of a new technique for acquiring dithered astronomical observations coined "CCD Phase Dithering." It was determined that the intrapixel sensitivity variations were less than +/- 0.5% in most cases. The lateral diffusion in the device was measured to be 7.41 mum in the device center, consistent with theoretical predictions. Charge spreading near the device edge resulted in an effective lateral diffusion increase of 0.19% in the vertical direction and no additional diffusion in the x-direction. Comparison of the photometric performance of normally dithered images to the phase dithered images found a mean difference of only 0.33% with the deviation between runs being 0.06% for the dithered and as little as 0.19% for the phase dithered. We conclude that the implications for performing precision cosmology experiments such as Supernova la Cosmology and Gravitational Weak Lensing are not adversely affected by intrapixel sensitivity variations in these devices; however, increased lateral diffusion near the device edges must be considered. Also, improvements in the photometric and astrometric fidelity of these detectors provided by the normal dithering process are available via the more efficient technique of CCD phase dithering.
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