Tesis doctoral de Angel Lizana Tutusaus
This thesis presents an exhaustive analysis of liquid crystal on silicon (lcos) displays for their application in diffractive optics. The scientific contributions included in this thesis have been published in a number of international journals in the field of optics, becoming as a whole, in a complete study of the performance of these devices. Following, the contents of this thesis are summarized: we propose a characterization method based on the mueller-stokes (m-s) formalism. This method has proved to be suitable to determining the mueller matrix of polarizing, partial polarizing or depolarizing samples. As a particular case, it is applied for the characterization of a twisted nematic (tn) lcos display as a function of the gray level, under quasi-normal incidence and for a wavelength equal to 633 nm. By means of the calibrated mueller matrices of the tnlcos display, the polarimetric properties of such device have been extracted. However, since mueller matrices are calibrated from radiometric measurements, no information of the phase is achieved. Thus, we propose a technique for a full polarimetric characterization of lcos displays, which combines the mueller and the jones formalisms. In particular, the lu-chipman polar decomposition is applied to extract the mueller matrix of the retarder, from which the equivalent jones matrix is achieved. In this situation, the prediction capability of both the intensity and the phase modulation allow us to obtain improved configurations for phase-only modulation with 360 phase depth, or for amplitude-mostly modulation. Some experimental results are provided in this work, pointing out the suitability of this technique. afterwards, the calibrating and optimizing methods are applied to analyze the influence of the wavelength and of the incident angle on the tnlcos display performance. We demonstrate that if an optimization is conducted for a specifics wavelength and incident angle, when varying one of these two parameters more than a certain range, configurations leading to different phase depth and to coupled amplitude and phase values are obtained. Therefore, a new optimization is required, leading to optimized phase-only modulation configurations. Some optical applications based on tnlcos display need both large phase shift and high incident angles. As the phase modulation decreases as the incident angle increases, we proposed an experimental set-up including a beam splitter. In this way, a large phase-modulation simultaneously with a right angle between the incidence and reflected beam are obtained. this thesis includes as well a study of different non-desired physical phenomena related to the lcos display performance. In particular, the origin of the effective depolarization, the time-fluctuations of the phase and of the anamorphic phenomenon are revised. Moreover, their effect in the lcos display efficiency is also analyzed. First, we propose a time-resolved characterization method that allows us to understand the origin of the effective depolarization phenomenon in lcos displays. Second, we provide experimental evidences for the time-fluctuations of the phase phenomenon. In order to achieve experimental information of this phenomenon, we have studied the suitability of two experimental set-ups, typically employed to measure the phase modulation, in presence of phase fluctuations: a diffraction based set-up and an interferometer based set-up. We demonstrate that the diffraction based set-up is capable to provide time-resolved measurements of the phase modulation but that in presence of phase-fluctuations, this set-up leads to wrong values of the phase modulation. Regarding to the interferometer based set-up, we show as it is suitable to obtain the mean phase modulation, independently of the phase fluctuations. Besides, the effect of the phase-fluctuations phenomenon in the efficiency of lcos displays is studied as well. In particular, we study the efficiency of different displayed binary-phase diffractive optical elements in presence of time fluctuations of the phase. Finally, experimental evidences for the anamorphic response of lcos displays are also provided and the strong relation between the orientation and the spatial frequency components of the image displayed on the lcos display with the anamorphic phenomenon is evidenced. finally, a second lcos display model, a parallel aligned (pa) lcos display, is also studied. We provide experimental measurements for the degree of the temporal phase fluctuations in a palcos display and we show that the amplitude of these fluctuations strongly depend on the format for the digital video signal (electrical sequence) addressed to the device. Besides, a mathematical model suitable to evaluate the efficiency of phase-only does in presence of time-fluctuations of the phase is proposed. Simulated and experimental data are provided, showing a good agreement and validating the usefulness of the model. The best configuration for our palcos display, in terms of efficiency, is achieved.
Datos académicos de la tesis doctoral «Characterization and optimization of liquid crystal on silicon displays for their application to diffractive optics«
- Título de la tesis: Characterization and optimization of liquid crystal on silicon displays for their application to diffractive optics
- Autor: Angel Lizana Tutusaus
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 16/05/2011
Dirección y tribunal
- Director de la tesis
- Juan Ignacio Pedro Campos Coloma
- Tribunal
- Presidente del tribunal: gaspar Orriols tubella
- pierre Ambs (vocal)
- (vocal)
- (vocal)