In the past four years, ORNL researchers have worked on many projects that are now categorized as photonics-related research. Achievements in photonics previously covered in the ORNL Review are described here.

ORNL researchers led by Tuan Vo-Dinh of the Health Sciences Research Division and researchers at the Thompson Cancer Survival Center in Knoxville, Tennessee, have developed a new laser technique for nonsurgically diagnosing certain cancers. Using ORNL's special data analysis method and laser light for "optical biopsy" diagnosis, physicians at the center can determine whether a tumor in the esophagus is malignant or noncancerous. The technique has been successfully demonstrated in more than 100 patients.

Vo-Dinh and his ORNL colleagues also have developed a much less expensive test for detecting polychlorinated biphenyls (PCBs) in environmental samples. The test uses strips of chemically treated paper that glow if exposed to PCBs and then excited by ultraviolet light. In 1994 this development received an R&D 100 Award from R&D magazine.

Another development by Vo-Dinh's group is surface-enhanced Raman optical data storage (SERODS). This laser-based technology, which has been licensed to two companies, uses the light-emitting properties of molecules to pack considerably more information onto compact discs. When fully developed, a 12-inch SERODS disc should be able to store information from 18,000 sets of a large encyclopedia

Vo-Dinh also developed a surface-enhanced Raman scattering (SERS) technique for measuring concentrations of chemical contaminants in water, soil, and wastes. This technology was licensed to a California company.

A sensitive high-tech SERS probe combining a computer, laser, optical fibers, and a power supply has been developed at ORNL to detect trace pollutants in groundwater. In field tests, the probe detected the groundwater contaminant trichloroethylene at levels as low as 150 parts per million.

Another ORNL invention has been a solar-powered "tracking" microchip smaller than a penny that emits an infrared signal. In addition, a receiver for detecting the microchip's signal from a distance at least twice as far as can be sent by other transmitters of comparable size has been devised and tested. The transmitter and receiver have agricultural and military applications.

Dosimeter badges now in use at Lockheed Martin Energy Systems, Inc., are the products of a thermoluminescent dosimetry (TLD) system developed jointly by ORNL and Y-12 Plant researchers. The TLD system automatically measures the amount and type of ionizing radiation to which personnel and the environment are exposed. It also analyzes, stores, and reports this information.

Brian Sales and Lynn Boatner in the Solid State Division have found that a higher degree of disorder is present in a crystal surface bombarded with ions than in a glass sample of the same composition. The work helps scientists better understand disordered solids and their effects on light transmission.

Using lasers and mass spectrometers, ORNL scientists Bob Hettich and Michelle Buchanan in the Chemical and Analytical Sciences Division are detecting structural and chemical changes in small fragments of DNA. In the Health Sciences Research Division, C. H. Chen and his colleagues have used laser mass spectrometry to measure the masses of DNA molecules and their ions up to 130 chemical bases in length. This system offers the potential for rapid sequencing of DNA bases to determine the composition of human genes.

ORNL researchers led by Loucas Christophorou in the Health Sciences Research Division have studied the behavior of electrons in matter. Applications of such knowledge include pulsed power switches, particle detectors, and insulating gases for underground transmission of electricity.

An optical sensor using two beams of laser light that can help monitor reactor performance has been developed by Marc Simpson of the Instrumentation and Controls Division. ORNL researchers led by Mike Cates in the Engineering Technology Division have found that fluorescence from phosphorus on hot surfaces in operating centrifuges and engines can reveal surface temperatures.

ORNL's Doug Mashburn has worked with Neocera, Inc., to develop a software-driven, pulsed-laser system for depositing high-temperature superconducting films of a desired composition and thickness. Mashburn's own elaborate laser ablation device shows promise for making thick superconducting films for use in wires and for synthesizing new materials and better phosphor coatings for flat display panels.

ORNL has evaluated technologies for making optical mirrors originally needed by U.S. defense programs to direct beams of light and particles toward military targets in space. These technologies, which are of interest to the optics industry, include single-point diamond machining that cuts metal at precise angles to get the correct mirror curvature. Such technologies, which were developed at the Y-12 Plant for making weapons components, are now being shared with industrial partners through cooperative research and development agreements.

In short, ORNL researchers have been working on a variety of photonics-related projects. Clearly, ORNL has been gaining expertise in this new area of science and technology while using its resources to solve problems in the information, energy, and environmental fields.

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