The location for the SPIE Annual Meeting (Denver, CO) is not the only thing that has changed this year—in 1996 the technical program promises to be richer than ever. With 68 conferences, more than 2000 papers, and an exhibition with more than 270 companies, the symposium should offer something for everyone. Traditionally strong in astronomical optics and optical engineering, the annual meeting now features four imaging-spectrometry conferences—a topic shifted over from the Aero Sense meeting—as well as SPIE fiberoptics conferences that have previously been run separately. Special review sessions highlight important areas, including optical polymers (CR63), inorganic optical materials (CR64), and optoelectronic processing (CR65), with a series of invited papers on state-of-the-art and future trends in each field.
Cross-disciplinary synthesis between chemistry and optical science and physics appears to be the dominant theme this year. Conferences will connect diverse groups of users, help researchers understand applications needs and engineers understand capabilities and limitations of the technology, and raise awareness of existing tools.
Microgravity material processing
The space environment offers unique possibilities for material processing. Reducing gravitationally induced convection minimizes problems with homogeneity and thickness uniformity in thin-film fabrication and crystal growth.
Vapor-phase growth of mercury cadmium telluride (HgCdTe) epitaxial films in microgravity shows significant advantages over ground-based techniques. Films of HgCdTe grown in orbit by scientists at Rensselaer Polytechnic Institute (Troy, NY) show an unusual degree of flatness in comparison with ground-based films, as well as significant improvements in homogeneity, single crystallinity, and carrier mobility (paper #2809-11).
Researchers from NASA's Marshall Space Flight Center (Huntsville, AL) have also grown HgCdTe crystals in orbit (paper #2809-02). The Advanced Automatic Directional Solidification Furnace operated in low gravity on the space shuttle for 11 days, allowing the group to correlate three-dimensional fluid flow with residual shuttle-acceleration vectors. From this database the group will optimize the acceleration vectors in the next mission to minimize flow and hope to produce more homogeneous crystals than can be made on earth.
Long a military staple, laser radar has imaging capabilities that are beginning to be exploited by researchers in other fields. The recently launched Near Earth Asteroid (NEAR) satellite carries a Nd:YAG laser-based laser radar system for surface mapping of the asteroid 433 Eros. Three sessions in conference #2811, Photonics for Space Environments IV, feature papers on the optical system and transmitter design, software, and instrument performance of the NEAR laser rangefinder.
Fiberoptic gyros turn 20
Conference #2837 celebrates the 20th anniversary of the fiberoptic gyroscope, which is one of the most commercially active areas in fiber sensors, with an estimated annual world market on the order of $100 million, excluding research and development. In addition to conventional navigational applications, fiberoptic gyros have been used as control systems for a floor-cleaning robot, an automatic lawnmower for soccer-field maintenance, and a remotely piloted helicopter for crop dusting (paper #2837-06).
The fiberoptic Sagnac interferometer, fundamental to the fiberoptic gyro, can operate as a current sensor in power-line-mapping applications (paper #2837-16) or for secure fiberoptic communications (paper #2837-17). The fiberoptic-gyro conference includes an associated IEEE standards meeting for fiberoptic gyros, and a special session, Strange and Memorable Events: the First 20 Years of Fiberoptic Gyro Development, is sure to offer unique insights.
Highlights on the optical-design front include a presentation on optical design with gradient-index (GRIN) optical elements. Glass components with axial-index gradients up to 0.2 offer new degrees of freedom in optical design, enhancing performance while reducing the number of components and thus system weight. Kenneth Moore of Focus Software (Tucson, AZ) will cover optical design with GRIN elements, discussing material properties and sample designs (paper #2863-39)
In many applications, the design process does not stop with the optical configuration. According to Stray Light and System Optimization conference cochair Stephen Pompea, today's optical systems have extremely high-performance requirements. "They almost force you to address stray-light issues because you can`t meet specs otherwise." Stray-light control necessitates knowledge of the properties of packaging materials. A new database compiles the experimentally determined scattering, reflectance, outgassing, and durability properties of a variety of surfaces, affording designers easy access to material that previously required intensive searching (paper #2864-35).