The increased demand for modern optical components necessitates an interferometric system that can rapidly and accurately measure wavefront phase errors during the complete fabrication process, from generation to polishing. The suitability of infrared wavelengths for several optical testing applications is well known, as are the greatly increased speed and accuracy of phase-shifting interferometric techniques. Therefore, this dissertation discusses extensively three topics: (1) the demonstration theoretically and experimentally of the feasibility of using a pyroelectric vidicon for infrared phase-shifting interferometry, (2) the design and fabrication of a prototype next-generation optical shop infrared phase-shifting interferometric system, and (3) the definition and quantification of the fundamental system performance parameters and limitations. Additionally, some application examples of infrared phase-shifting interferometry are presented, and specific recommendations for future work are included with the conclusions.

Pyroelectric Detector (PED) models are developed considering the classical heat balance equation to simulate the detector’s response under specified radiation conditions. Studies on the behaviour of a PED are presented under the conditions of step function and a pulsed load. Finite Element Methods (FEMs) have been used to obtain 3D models of the resulting temperature field in a Lithium Tantalate (LiTaO3) pyroelectric crystal, incorporated in a complete commercial detector, taking into account details of its geometry and thermal connectivity. The novelty is the achieved facility to predict the response to pulsed radiation, which is valuable for the engineering of pulsed-source sensor systems requiring detection at room temperature. In this thesis, we present a signal processing (SP) algorithm, which combines the principle of Quadrature Synchronous Demodulation (QSD) and Gated Integration (GI), to achieve an improved signal-to-noise ratio (SNR) in pulsed signal measurements. As a first step, the pulse is bracketed by a gating window and the samples outside the window are discarded. The gate duration is calculated to ensure that the periodic signal at the output has an 'apparent' duty factor close to 0.5. This signal is then fed continuously for QSD to extract the magnitude and phase of its fundamental component, referenced to a sinusoidal signal with period defined by the gate length. An improved SNR performance results not only from the increase of the average signal energy, but also from the noise suppression inherent to the QSD principle. We introduce this method as Gated Quadrature Synchronous Demodulation (GQSD), emphasizing the synergy between GΙ and QSD.

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references.

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Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

The master‘s thesis deals with utilization of infrared camera for temperature measurement of electrical machines. The first part describes non-contact temperature measuring, the second part describes principle of sensors that evaluate quantity of incident infrared radiation. In the next part there is termovision camera SAT-HY 6800 presented and the instructional manual for SAT Report computer programme created. This computer programme is used for analyzing of termovision pictures from the SAT-HY 6800 termovison camera. The chapter 7 describes temperature measuring of one-phase asynchronous motor type J22TO484. The chapter 8 describes temperature measuring of semiconductor components of EC motor G6 series. Both of these motors are produced by ATAS elektromotory Náchod a.s. The last part of the thesis describes creation of animation of one-phase asynchronous motor type J22TO455. The animation was created in 3ds Max computer programme.