Thesis (M.S.)--Ohio State University, 1984. / Includes bibliographical references (leaves 118-119). Available online via OhioLINK's ETD Center

We report results for the development of a flow-through integrated cavity absorption meter (ICAM.) Absorption measurements have been made with 2% or less change in the signal in the presence of up to 10 m-1 of scattering in the medium. The operating range of the ICAM ranges from 0.004 m-1 to over 40 m-1 of absorption. This range allows one to use a single instrument to measure the absorption from sediment laden rivers out to the cleanest of ocean waters. Further, the ICAM signal has been shown to be independent of the flow rate and turbulence in the medium. In addition we report the development of a diffuse reflector which, to our best knowledge, has the highest measured diffuse reflectivity of 0.998 at 532 nm and 0.996 at 266 nm. We also show that the average distance a photon travels between successive reflections in an integrating cavity of arbitrary shape is four times the volume divided by the surface area, 4 V/S. Further, for a cavity which is formed by planes tangent to an inscribed sphere and which maintains a homogeneous and isotropic field, the average distance traveled by a photon between successive reflections is equal to 4 V/S of the inscribed sphere. Thus, each cavity has the same ratio of V/S as the inscribed sphere. These advances lead to an increase in the sensitivity of absorption spectroscopy. The sensitivity approaches that of cavity ring down spectroscopy (CARS), without the adverse scattering effects traditionally associated with CARS.

The purpose of this paper is to fabricate optical waveguide reflectors to reflect the incident optical mode of multi-mode interference coupler by the etched vertical mirror surfaces. We used the design of etched vertical mirror surfaces to bend the incident optical mode, and changed the length of multi-mode interference coupler for the power splitting ratio. By the simulation and design, we could use the multi-mode interference coupler to fabricate optical waveguide reflectors. A 1.52µm symmetric quantum well InGaAlAs/InGaAs epitaxial wafer is used to fabricate the devices. In the device design, we designed a optical waveguide reflector of two inputs and outputs with 90¢X angle. We fabricated a Fabry-Perot laser by two optical waveguide reflectors with 90¢X angle, a 1x2 multi-mode interference coupler and a ring cavity. In addition, we designed optical waveguide reflectors of one input and two inputs, and utilized them to fabricate a Fabry-Perot laser. We also utilized an optical waveguide reflector of one input or two inputs directly to fabricate Fabry-Perot lasers. In fabrication process, firstly, we etched the waveguide to the depth of about 1.81µm by multi-step wet etching. In order to reduce bending loss, we made deep etching for the outside of curve waveguide. Then, we etched the mirror to the depth of about 6µm by multi-step wet etching to have a greater variation of refractive index to reflect the mode of optical waveguide reflectors. Finally, we used polyimide to flatten the sides of the ridge waveguides and evaporated metal pad over the polyimide.

We report results for the development of a flow-through integrated cavity absorption meter (ICAM.) Absorption measurements have been made with 2% or less change in the signal in the presence of up to 10 m-1 of scattering in the medium. The operating range of the ICAM ranges from 0.004 m-1 to over 40 m-1 of absorption. This range allows one to use a single instrument to measure the absorption from sediment laden rivers out to the cleanest of ocean waters. Further, the ICAM signal has been shown to be independent of the flow rate and turbulence in the medium. In addition we report the development of a diffuse reflector which, to our best knowledge, has the highest measured diffuse reflectivity of 0.998 at 532 nm and 0.996 at 266 nm. We also show that the average distance a photon travels between successive reflections in an integrating cavity of arbitrary shape is four times the volume divided by the surface area, 4 V/S. Further, for a cavity which is formed by planes tangent to an inscribed sphere and which maintains a homogeneous and isotropic field, the average distance traveled by a photon between successive reflections is equal to 4 V/S of the inscribed sphere. Thus, each cavity has the same ratio of V/S as the inscribed sphere. These advances lead to an increase in the sensitivity of absorption spectroscopy. The sensitivity approaches that of cavity ring down spectroscopy (CARS), without the adverse scattering effects traditionally associated with CARS.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 226-230). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

A method of calculating the secondary pattern of a reflector illuminated by a feed array is developed. Geometrical optics is used to determine the incident field via a coordinate transformation approach. The incident field from each element is superimposed to form the total field used in finding the surface currents of the physical optics radiation integral. The technique allows each element to be arbitrarily excited, positioned and oriented. The element patterns may be different allowing mutual coupling to be included. / M.S.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / The design of a telemetry tracking system is generally centered around its desired RF performance which is typically specified in terms of beamwidth, gain and/or G/T. These parameters determine the size of the reflector used in a given application and consequently dictate the required size and performance of the associated pedestal. Any subsequent improvement in the RF performance of such a system is primarily achieved by increasing the size of its reflector. The magnitude of the improvement realized is therefore limited by the load handling capability of the pedestal. In most instances, the substitution of a larger reflector with its increased inertia and wind loading causes a significant degradation in the dynamic performance of the tracking system. This paper describes how the figure of merit (G/T) of a specific dual axis telemetry tracking system can be improved by a minimum of 7.3 dB/K° without impacting its dynamic performance or increasing its weight. These impressive results are made feasible by the innovative pairing of a unique design planar reflector with a novel implementation of the conical scanner technology. The FLAPS™ reflector incorporates a newly developed concept which features lightweight construction and very low wind load coefficients [1, 2]. The conical scanner is a lightweight version of the DECS tracking feed system described in the referenced technical paper [3].

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The use of low windload FLAPS™ antennas in telemetry tracking systems yields sizable savings in system cost due to the reduced requirements imposed on the pedestal assembly and on the underlying support structure. Traditionally the use of these antennas has been limited to applications in which frequency bandwidths did not exceed 10-13%. This paper describes a variation of the FLAPS™ technology which allows operation over bandwidths in excess of 35% and makes it usable in broadband systems. Two new applications are feasible: one for a ground based telemetry system operating in the 1435-1850 or 1750-2400 MHz band and one for a shipboard satellite communication system operating in the 4000-6000 MHz band.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The requirement for a lightweight, quick deployment C-Band satellite communication antenna system for Aegis Class Destroyers has been addressed and this paper describes a novel solution currently being implemented. The new antenna system takes advantage of the low windload properties of the FLAPS™ (Flat Parabolic Surface) reflector and features a broadband FLAPS™ reflector mounted on a lightweight, high performance X-Y positioner. The system is designed in a modular fashion and operates in a shipboard environment without the protection of a radome. The system is stabilized to counteract the ship's motion, operates without counterweights, weighs less than 250 kg and provide communication links in the 3900 to 4100 MHz and 6000 to 6200 MHz frequency bands.