The use of a microchannel plate as an optical encoding device has many advantages. These include large surface area and large-scale signal averaging. This instrument was designed to obtain and interpret the information generated by the optical transform of a microchannel plate. It will be shown that a large amount of information about solution interactions and properties can be obtained from such an instrument. / Master of Science

This thesis presents a simple Real Time Embedded Control System (RTECS) in an application of Intelligent Structure Monitoring. Research in smart structures, especially the area of vibration suppression, has warranted the investigation of advanced computing environments. Real time PC computing power has limited development of high order control algorithms. The system discussed allows for implementation of l/O intensive algorithms and provides capability for advanced system development. In an application of Modal Domain Sensing for Vibration Control, RTECS is compared to a PC AT based system for overall functionality and speed. Using a model development procedure, the system is optimized for efficient operation and speed. This includes minimizing the computational overhead associated with I/O. A comparison shows an order of magnitude I increase in system speed with larger speed increases discussed. The results provide an avenue for high order control system design. This leads to more accurate device modeling and a higher level of system control. RTECS employs a novel RISC microcontroller capable of 15 MIPs continuous performance and burst rates of 40 MIPs. Advanced CMOS circuits are integrated on a single printed circuit board measuring 100 mm by 160 mm and require only 1 Watt of power. An operating system written in Forth provides the flexibility for high speed operation in short development cycles. / Master of Science

This investigation was concerned with the development of a fiber optic evanescent sensor. Such a sensor is based upon the lateral regions of the waveguide and their interaction with a chemical environment. The basic principles and concepts involved in the construction of a fiber optic spectroscopic evanescent field sensor are developed. From this fundamental knowledge a series of sensors were constructed to characterize their responses. First, the response to simple refractive index changes and angle launch conditions were explored. This demonstrated the light interaction with the measurement environment. What followed was the use of these sensors to make spectrochemical absorption measurements suitable for a calibration curve of 1.25 x 10⁻² to 1.22 x 10⁻⁹ M concentrations for various dye systems. As a consequence of the spectrochemical studies the unique interaction between the chemical environment and the silica surface was observed. This response is based upon the chemical reactivity of the silica surface and the chemical environment. This prompted the investigation of the ion exchange characteristics of the silica waveguide surface and the chemical environment. In this investigation the exchange selectivities of the alkali, alkali earth and lanthanide metals were determined. Finally, a series of innovative fiber optic sensors base upon interferometric and refractometric measurements were investigated. These designs were based upon the fabrication characteristics of glass and plastic fiber optic waveguides. / Ph. D.

This thesis addresses the design of ferrite cores for inductive proximity sensors of the ECKO type. The purpose of this pursuit is to identify several ferrite cores that have the highest performance in terms of the sensor's sensing ability. The purpose of the ferrite core in these sensors is to concentrate and focus the alternating magnetic field produced by a current-carrying winding. The magnetic flux is specifically aimed at the sensor's metal target, and since the sensing operation is dependent on the generation of eddy currents within the metal target, the range at which the target can be detected is a direct function of how optimally the magnetic flux is cut by the target. In this study the target is a circular disk, just as is used in industry for standardization procedures. To begin with, a theoretical analysis is performed to identify those factors that affect sensing performance; this development makes use of fundamental electromagnetic theory. Subsequently, the performance of a score or so ferrite geometries is evaluated by computer simulation using the results of the theory to facilitate effective comparison. The computer simulation is performed using finiteelements based electromagnetics solver software from ANSOFT. Lastly, some of the geometries studied with the simulation are constructed and their sensing performance evaluated as verification of the simulation and its theoretical backing. / Master of Science

Methods designed to improve the practicality of the elliptical-core two-mode optical fiber sensors for use in real-life applications are presented. The improvements include the development of insensitive lead fibers and an optical device which allows fringe counting at the output of the sensor. The insensitive leads eliminate extraneous perturbations and effectively isolate the sensing region. The fringe counting optics are designed to generate quadrature-phase shifted signals, thereby allowing the determination of whether the strain is increasing or decreasing. Work performed to advance the understanding of the effect of sensor placement within a composite specimen is also presented. Optical fiber sensors are embedded between different laminae of a graphite-epoxy composite panel, and the outputs of the sensors are shown to be proportional to the distance of the sensor from the neutral axis. / Master of Science

This dissertation describes the design, development and results of a simple, inexpensive, rugged, pyroelectric heat-of-reaction detector that can be made in many configurations. The measured heat of reaction results from the reaction of a substrate on an enzyme. The enzyme is immobilized in a flow channel with a pyroelectric polymer film, poly(vinylidene fluoride) or PVDF. The sample is introduced into the flow channel using flow injection analysis technology. The heat from the reaction causes the pyroelectric material to produce an electrical potential proportional to the change in temperature which, in turn, is proportional to the substrate concentration. This potential is amplified and recorded. A differential instrument amplifier produces a difference signal from a sample and reference PVDF film. This removes noise caused by stray electromagnetic radiation and piezoelectric pressure responses. A conventional Flow Injection Analysis unit was employed. The FIA flow rate was four ml/min and the time from injection to peak maximum was less than three seconds, with a return to baseline of less than thirty seconds. This gives a quick analysis time and a reasonable number of analyses per unit time. Data interpretation is straight forward, peak height is proportional to the concentration. A 70 μl sample gives a good response. Larger samples do not improve the signal. The system showed minimum detectable number of moles that is comparable to other methods, 7 x 10⁻⁸ moles. The detector showed good response for more than two orders of magnitude. The results show excellent correlation to the modeled system of heat trans+er through the PVDF sensor. / Ph. D.