The production of a variable array of optical point sources from a single point source can be achieved through the self- imaging properties inherent in a rectangular waveguide. Two prototype devices, based upon this concept, were designed and constructed. The resulting output patterns are discussed along with future design considerations and applications.
This work involves the design and development of species specific gene (DNA) probes designed to detect Pseudomonas species. A non radioactive detection system for DNA was designed to detect the presence of these microbes in environmental samples for biomonitoring applications. The details of the methodology and their applicability for various environmental analyses is discussed below.
Catheter-sized absorbance sensors have been constructed and tested using the medically significant dye indocyanine green as an analyte. Sensors were found to be equally usable with conventional wavelength scanning instrumentation or with a very compact solid state instrument. Statistical evaluation of the data acquired with these small sensors showed that accurate working curves provide high sensitivity and wide dynamic range of use. Potential uses of these sensors are suggested.
A new efficient fiber optic absorbance sensor is described. The sensor can be configured with optical pathlengths from a few millimeters to 10 cm while maintaining high throughput. The sensor contains a graded index (GRIN) microlens which is ground for a specific sensor optical configuration. The sensor is able to be configured in several diameters ranging from sizes that fit within clinically acceptable gauge hypodermic needles to several millimeter diameter sizes. The sensor has currently been tested for the near-UV-VIS and near-IR spectral regions. Optical test results for several sensor sizes are presented and compared to sensor configurations described previously in the literature. A brief analysis of the sensor design is given in terms of the physical optics of the graded-index lens/multimode fiber optic couples which lead to high optical efficiencies. Example numerical simulations of the sensor optical efficiency are presented and compared with experimental results. Sample spectra and performance results also are presented.
Radiopharmaceuticals containing <SUP>99m</SUP>Tc, a gamma emitting radionuclide, are commonly used in nuclear medicine to image specific organs for the purpose of diagnosis. Following injection of a chemical complex of this isotope and concentration of the activity within the organ of interest, scanning with a gamma ray camera provides an image from which diagnostic information can be obtained. Although, in most instances the composition of the injected radiopharmaceutical is known, the chemical form of the agent that is actually responsible for the image has not been identified and may represent an altered form due to in vivo reaction. Sensors that could be implanted in specific organs in order to specify the chemical form of the radioactive complex that is imaging an organ would be especially useful. In order to accomplish this goal, sensors for in vivo monitoring of imaging agents that are used in nuclear medicine are being developed. Such sensors must be multiwavelength since chemical information is contained in the spectrum of agents. A brief outline of the results of our efforts to make highly efficient catheter-sized absorbance sensors is presented.