Browsing by Author "Olson, Kyle"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Can You Hear Me Now? Solving the Headphone Problem
    (2009-04-08) Hornung, Stephanie; Evenson, Maureen; Pope, Zach; Olson, Kyle; Cook, David
    This project will develop a product that will be embedded into headphones to prevent the wearer from missing essential communication, either from conversation or emergency sirens (fire alarms, tornado sirens, emergency vehicle sounds, etc.). It will monitor ambient sound and determine whether or not music should be interrupted. A microphone will pick up sound from the environment, then analysis software will process it to determine the next step. If the sound is determined to be either close range human speech or an emergency siren, the code will signal the music to cease. If neither of these is recognized, the music will continue. The bulk of the project lies in developing software that can differentiate human speech from other ambient sounds. Thus far, we are writing code and figuring out what distinguishes human speech from other ambient noise. This includes spectrogram analysis of various sound recordings. From our research, we know that we must analyze each sound to approximately 1/100th of a second (this is defined to be a "feature"). Each feature is assigned a probability that it appears as a portion of a spoken word. We cross-reference each probability with 1000's of feature charts of recognizable human speech patterns to determine if the sound is from a human voice. Based on this probability, we decide if the word is human speech. The code we create to do this will be transferred to a pic microcontroller, which interfaces with the microphone and the music player, allowing it to quickly respond to human speech or emergency signals.
  • Thumbnail Image
    Item
    High Power Continuous Wave Laser Heating and Damage with Contamination, and Non-Uniform Spectrally Dependent Thermal Photon Statistics
    (2015-12) Olson, Kyle
    A model is presented and confirmed experimentally that explains the anomalous behavior observed in the continuous wave (CW) excitation of thermally-isolated optics. Very low absorption, high reflective optical thin film coatings of HfO2 and SiO2 were prepared. When illuminated with a laser for 30s the coatings survived peak irradiances of 13MW/cm2. The temperature profile of the optical surfaces was measured using a calibrated thermal imaging camera; about the same peak temperatures were recorded regardless of spot size, which ranged between 500μm and 5mm. This phenomenon is explained by solving the heat diffusion equation for an optic of finite dimensions, including the non-idealities of the measurement. An analytical result is also derived showing the transition from millisecond pulses to CW, where the heating is proportional to the laser irradiance (W/m2) for millisecond pulses, and proportional to the beam radius (W/m) for CW. Contamination-induced laser breakdown is often viewed as random and simple physical models are difficult to apply. Under continuous wave illumination conditions, failure appears to be induced by a runaway free-carrier absorption process. High power laser illumination is absorbed by the contaminant particles or regions, which heat rapidly. Some of this heat transfers to the substrate, raising its temperature towards that of the vaporizing particle. This generates free carriers, causing more absorption and more heating. If a certain threshold concentration is created, the process becomes unstable, thermally heating the material to catastrophic breakdown. Contamination-induced breakdown is exponentially bandgap dependent, and this prediction is borne out in experimental data from TiO2, Ta2O5, HfO2, Al2O3, and SiO2. The spectral dependence of blackbody radiation and thermal photon noise is derived analytically for the first time as a function of spectra and mode density. An algorithm by which the analytical expression for the variance can be found for any spectral distribution is also presented. The analytical results of some simple distributions are found and shown to be inaccurately approximated with a uniform spectral distribution highlighting the importance of the finding. Two microcavities are then presented to exemplify enhanced or inhibited photon statistics effects on the cavity.