Jump to navigation
New experiments in diffractive optics and polarization control using a programmable liquid crystal display
Hernandez, Travis James
We analyze several ideas concerning diffraction from a liquid crystal display. First, we show that a lens system may satisfy the conditions of Fraunhofer diffraction in the focal plane of the lens, as it will be used throughout this thesis. We introduce the Epson LCD used in this thesis as a diffractive optical element, and calibrate this device. Then, we analyze several diffraction gratings to demonstrate various operation modes, and capabilities of the LCD. With theory and experiment, we review Dammann gratings and their ability to produce equal intensity diffracted orders. This theory is extended to two and three dimensions to produce three dimensional arrays of equal intensity spots. By combining two masks using complimentary random functions, we provide a new 3D Dammann mask capable of generating an array of spots located at the lattice points of a body centered cubic crystal structure. We review optical vortices diffracted from spiral phase plates. In previous studies when the mask was partially blocked, the beams rotated 90 degrees from the mask to the Fraunhofer region. We undertake a comprehensive analysis of the Fraunhofer diffraction from a spiral phase plate to provide explanation for the 90 degree rotation. We show experimentally that the vortices rotate as a function of distance. Previous research shows that this rotation is a function of the sign of the charge, but not the magnitude. However, we provide experimental results that show this rotation is dependent on charge magnitude. Finally, we show that the liquid crystal display may be used to control the polarization of the zero order transmitted light. We then produce a screen with multiple polarizations (left, right, and circular) by imaging a mask using only the zero order light. Then, using two passes through the LCD, we show that we can control the polarization state of the first order diffracted light. Both theory and experiment are used to support the claims.
Master of Science (M.S.) San Diego State University, 2011
© 2015 SDSU Library & Information Access. All Rights Reserved.