This thesis consists of two parts: a report on the use of a binocular Shack-Hartmann (SH) sensor to study the dynamic correlation of ocular aberrations; and the application of an adaptive optics (AO) system to investigate the effect of the manipulation of aberrations on the accommodation control. The binocular SH sensor consists of one laser source and one camera to reduce system cost and complexity. Six participants took part in this study. Coherence function analysis showed that coherence values were dependent on the subject, aberration and frequency component. Inter-ocular correlations of the aberration dynamics were fairly weak for all participants. Binocular and monocular viewing conditions produced similar wavefront error dynamics. The AO system has a dual wavefront sensing channel. The extra sensing channel permits direct measurement of the eye's aberrations independent of the deformable mirror. Dynamic correction of aberrations during steady-state fixation did not affect the accommodation microfluctuations, possibly due to the prior correction of the static aberration level and/or the limited correction bandwidth. The inversion of certain aberrations during dynamic accommodation affected the gain and latency of accommodation response (AR), suggesting that the eye used the aberrations to guide its initial path of accommodative step response. Corrections of aberrations at various temporal locations of AR cycle produced subject- and aberration-dependent results. The gain and phase lag of the AR to a sinusoidally moving target were unaffected by aberration correction. The predictable nature of the target had been suggested as the reason for its failure to produce any significant effect on the AR gain and phase lag.

Reconstruction of continuous signals from a number of their discrete samples is central to digital signal processing. Digital devices can only process discrete data and thus processing the continuous signals requires discretization. After discretization, possibility of unique reconstruction of the source signals from their samples is crucial. The classical sampling theory provides bounds on the sampling rate for unique source reconstruction, known as the Nyquist sampling rate. Recently a new sampling scheme, Compressive Sensing (CS), has been formulated for sparse signals. CS is an active area of research in signal processing. It has revolutionized the classical sampling theorems and has provided a new scheme to sample and reconstruct sparse signals uniquely, below Nyquist sampling rates. A signal is called (approximately) sparse when a relatively large number of its elements are (approximately) equal to zero. For the class of sparse signals, sparsity can be viewed as prior information about the source signal. CS has found numerous applications and has improved some image acquisition devices. Interesting instances of CS can happen, when apart from sparsity, side information is available about the source signals. The side information can be about the source structure, distribution, etc. Such cases can be viewed as extensions of the classical CS. In such cases we are interested in incorporating the side information to either improve the quality of the source reconstruction or decrease the number of the required samples for accurate reconstruction. A general CS problem can be transformed to an equivalent optimization problem. In this thesis, a special case of CS with side information about the feasible region of the equivalent optimization problem is studied. It is shown that in such cases uniqueness and stability of the equivalent optimization problem still holds. Then, an efficient reconstruction method is proposed. To demonstrate the practical value of the proposed scheme, the algorithm is applied on two real world applications: image deblurring in optical imaging and surface reconstruction in the gradient field. Experimental results are provided to further investigate and confirm the effectiveness and usefulness of the proposed scheme.

Zugl.: Innsbruck, Univ., Diss., 2007

Zugl.: Diss.

"Zugl.: Bochum, Univ., Diss., 2007"--T.p. verso. / Includes bibliographical references (p. [231]-249).

The testing technique with high dynamic range is required to meet the measurement of refractive wavefront with large distortion from test refractive surface. A general deflectometric method based on reverse Hartmann test is proposed to test refractive surfaces. Ray tracing of the modeled testing system is performed to reconstruct the refractive wavefront from test surface, in which computer-aided optimization of system geometry is performed to calibrate the geometrical error. For the refractive wavefront error with RMS 255 mu m, the testing precision better than 0.5 mu m is achieved.

Abstract Modern NMR methods in liquids are based on the transfer of polarisation from nucleus to nucleus to generate multidimensional heteronuclear correlation spectra. The factors that influence the efficiency of heteronuclear polarisation transfer in multi-pulse experiments, and in that way the quality of spectra are the subject of this thesis. The flow of coherence through pulse sequences can be designed and analysed with the aid of product operator calculations. Results of the study include improvements to quantitative two-dimensional shift-correlated experiments, and demonstration of the benefits of closely spaced 180° pulse trains in polarisation transfer steps in long-range correlation experiments and isotope editing filters.

No description available.

Cornell and Hartmann (2007) developed a constructionist framework that can describe the development of racial and ethnic identities. Yet this framework has greater utility than its authors have intended as it also provides the best rubric to date for comprehending the transitions between collective identity group types. This study engages in a thorough investigation of the development of racial and ethnic identities within the context of those that precede it via an ethnohistorical analysis. It also demonstrates that this framework is capable of describing pre-modern religious and national identity types in addition to racial and ethnic identity types. This permits it to demonstrate that this framework can also be utilized in the analysis of identities and identity types in the pre-modern era, in addition to the modern examples that Cornell and Hartmann have used. To this end Weber‟s concept of the ideal type is used to support the examination of identity transitions among pre-Mexicans, Mexicans and Americans of Mexican descent in the ethnohistorical analysis. This methodological approach is in accordance with Romano‟s (1968) indication that the most effective way of understanding the way that Mexican persons define themselves is through a historical and not a sociological investigation. This investigation encapsulates the transition from pre-modern religious identities in the Iberian Peninsula, to the appearance of racial and national identities in the Viceroyalty of New Spain and the Mexican Republic. It examines a second racialization of those that lived within the northern Mexican provinces as Mexicans in the newly conquered Southwestern United States come into contact with the dominant white majority of the United States. The ethnohistorical analysis concludes with a description of the emergence of four distinct identity types among Americans of Mexican descent, each a means to combat the normative discrimination they faced.

This thesis consists of two parts: a report on the use of a binocular Shack-Hartmann (SH) sensor to study the dynamic correlation of ocular aberrations; and the application of an adaptive optics (AO) system to investigate the effect of the manipulation of aberrations on the accommodation control. The binocular SH sensor consists of one laser source and one camera to reduce system cost and complexity. Six participants took part in this study. Coherence function analysis showed that coherence values were dependent on the subject, aberration and frequency component. Inter-ocular correlations of the aberration dynamics were fairly weak for all participants. Binocular and monocular viewing conditions produced similar wavefront error dynamics. The AO system has a dual wavefront sensing channel. The extra sensing channel permits direct measurement of the eye¿s aberrations independent of the deformable mirror. Dynamic correction of aberrations during steady-state fixation did not affect the accommodation microfluctuations, possibly due to the prior correction of the static aberration level and/or the limited correction bandwidth. The inversion of certain aberrations during dynamic accommodation affected the gain and latency of accommodation response (AR), suggesting that the eye used the aberrations to guide its initial path of accommodative step response. Corrections of aberrations at various temporal locations of AR cycle produced subject- and aberration-dependent results. The gain and phase lag of the AR to a sinusoidally moving target were unaffected by aberration correction. The predictable nature of the target had been suggested as the reason for its failure to produce any significant effect on the AR gain and phase lag.