MULTI-WAVELENGTH SPECKLE REDUCTION FOR LASER PICO-PROJECTORS USING DIFFRACTIVE OPTICS

Personal electronic devices, such as cell phones and tablets, continue to decrease in size while the number of features and add-ons keep increasing. One particular feature of great interest is an integrated projector system. Laser pico-projectors have been considered, but the technology has not been developed enough to warrant integration. With new advancements in diode technology and MEMS devices, laser-based projection is currently being advanced for pico-projectors. A primary problem encountered when using a pico-projector is coherent interference known as speckle. Laser speckle can lead to eye irritation and headaches after prolonged viewing. Diffractive optical elements known as diffusers have been examined as a means to lower speckle contrast. Diffusers are often rotated to achieve temporal averaging of the spatial phase pattern provided by diffuser surface. While diffusers are unable to completely eliminate speckle, they can be utilized to decrease the resultant contrast to provide a more visually acceptable image. This dissertation measures the reduction in speckle contrast achievable through the use of diffractive diffusers. A theoretical Fourier optics model is used to provide the diffuser’s stationary and in-motion performance in terms of the resultant contrast level. Contrast measurements of two diffractive diffusers are calculated theoretically and compared with experimental results. In addition, a novel binary diffuser design based on Hadamard matrices will be presented. Using two static in-line Hadamard diffusers eliminates the need for rotation or vibration of the diffuser for temporal averaging. Two Hadamard diffusers were fabricated and contrast values were subsequently measured, showing good agreement with theory and simulated values. Monochromatic speckle contrast values of 0.40 were achieved using the Hadamard diffusers. Finally, color laser projection devices require the use of red, green, and blue laser sources; therefore, using a monochromatic diffractive diffuser may not optimal for color speckle contrast reduction. A simulation of the Hadamard diffusers is conducted to determine the optimum spacing between the two diffusers for polychromatic speckle reduction. Experimental measured results are presented using the optimal spacing of Hadamard diffusers for RGB color speckle reduction, showing 60% reduction in contrast.

Silicon Photonic Device for Wavelength Sensing and Monitoring

Over the last decade advances and innovations from Silicon Photonics technology were observed in the telecommunications and computing industries. This technology which employs Silicon as an optical medium, relies on current CMOS micro-electronics fabrication processes to enable medium scale integration of many nano-photonic devices to produce photonic integrated circuitry. However, other fields of research such as optical sensor processing can benefit from silicon photonics technology, specially in sensors where the physical measurement is wavelength encoded. In this research work, we present a design and application of a thermally tuned silicon photonic device as an optical sensor interrogator. The main device is a micro-ring resonator filter of 10 $\mu m$ of diameter. A photonic design toolkit was developed based on open source software from the research community. With those tools it was possible to estimate the resonance and spectral characteristics of the filter. From the obtained design parameters, a 7.8 x 3.8 mm optical chip was fabricated using standard micro-photonics techniques. In order to tune a ring resonance, Nichrome micro-heaters were fabricated on top of the device. Some fabricated devices were systematically characterized and their tuning response were determined. From measurements, a ring resonator with a free-spectral-range of 18.4 nm and with a bandwidth of 0.14 nm was obtained. Using just 5 mA it was possible to tune the device resonance up to 3 nm. In order to apply our device as a sensor interrogator in this research, a model of wavelength estimation using time interval between peaks measurement technique was developed and simulations were carried out to assess its performance. To test the technique, an experiment using a Fiber Bragg grating optical sensor was set, and estimations of the wavelength shift of this sensor due to axial strains yield an error within 22 pm compared to measurements from spectrum analyzer. Results from this study implies that signals from FBG sensors can be processed with good accuracy using a micro-ring device with the advantage of ts compact size, scalability and versatility. Additionally, the system also has additional applications such as processing optical wavelength shifts from integrated photonic sensors and to be able to track resonances from laser sources.

Lecture by John Henry, given at Florida International University, December 8, 2013

John Henry discusses his background and his work. Comments by Javier Hernández-Lichtl, CEO of Baptist West Kendall Hospital. Introduction by Carol Damien.

Lecture by Joel Perlman, given at Florida International University, December 4, 2011

Joel Perlman talks about his life and his evolution as an artist. Introduction by Carol Damian.

Lecture by Juan Manuel Echavarria, given at Florida International University, March 7, 2012

Juan Manuel Echavarria discusses his exhibition which includes 24 paintings created by men and women who participated in Colombia’s war. All 35 participants were rank and file soldiers demobilized either under the Ley de Justicia y Paz (Justice and Peace Law), or because they deserted or were wounded in combat. They spent two years painting their personal experiences, illustrating the rural tragedy; witnessing the involvement of drug traffickers, capturing the painful repertoire of violence in Colombia, which for years has played out alongside daily life, blending in with normality. Introduction by Carol Damien.

Lecture by Susan Stamberg, given at Florida International University, September 17, 1999

Susan Stamberg talks about the cultural impacts of Ernest Hemingway, Georgia O'Keffe, Frank Sinatra, and Elia Kazan. Introduction by Dahlia Morgan.

Lecture by Cheech Marin, given at Florida International University, 2004

Cheech talks about Chicano art, his own art education and what led him to build his collection. Introduction by Dahlia Morgan.

Lecture by Tom Otterness, given at Florida International University, 2007

Tom Otterness talks about his background and the influences on his work. He answers questions about his work from the attendees. Comments by Melissa Levine. Introduction by Amy Pollack. Lecture held at the Avenue of the Arts at Florida International University.

Lecture by Robert Adanto, given at Florida International University, October 24, 2008

Robert Adanto talks about his background and how it impacted the making of his documentary film "The Rising Tide'. He also discusses the film and some of the featured artists in greater detail.

Lecture by Ursula von Rydingsvard, given at Florida International University, April 21, 2012

Ursula von Rydingsvard talks about her work and focuses her lecture on the process. Introduction by Carol Damian.

Lecture by Glenn Lowry, given at Florida International University, March 13, 1998

Glenn Lowry talks about the state of affairs at the MoMA as well as some of the issues the museum faces. Introduction by Dahlia Morgan.

Lecture by Luis Jimenez, given at Florida International University, September 22, 1999

Luis Jimenez provides a walk through tour of his exhibit and discusses each piece individually while sharing his experiences and life stories. The exhibit includes many of his drawings.

Lecture by Sam Hunter, given at Florida International University, October 24, 1997

Sam Hunter explores the theme of the romantic sublime in the late 19th and early 20th century. Introduction by Dahlia Morgan.

Lecture by Virginia Mecklenberg, given at Florida International University, 2009

Virginia Mecklenburg discusses various 20th century American artists. Introduction by Carol Damian.