The application of laser excited fluorescence to the detection and identification of latent fingerprints was first accomplished ten years ago. The development of the technology has progressed rapidly with the introduction of commercial equipment by several manufacturers. Systems based on Argon-ion, Copper-vapor, and frequency-doubled Nd:YAG lasers are compared. The theoretical basis of detection by fluorescence is discussed along with the more useful techniques of dye staining. Other applications of the laser excited fluorescence in forensic investigation include gunshot residue analysis, serology, collection of trace evidence, and document examination.

Some of the main factors affecting the analysis of solid steel using laser-induced break-down spectroscopy (LIBS) have been investigated and are reported here. Pulses from an electro-optically Q-switched Nd:YAG laser were focused on steel samples to generate a high temperature plasma. The spectrally resolved plasma light was time resolved and detected using a photodiode array. The effects that changes in the lens-to-sample distance, laser pulse energy, and position of the imaging lens had on the LIBS analysis are described. These effects were minimized by ratioing the absolute element signals to adjacent Fe-lines. Calibration curves for Mn, Si, and Cr are presented and the accuracy and precision of LIBS analysis listed for several elements.

Time-resolved laser-induced breakdown spectrometry has been combined with the long spark technique and applied to the rapid determination of beryllium in beryllium-copper alloys. Excitation temperatures within the spark were determined from Boltzmann plots on Cu and Cu lines. The method can be extended to other elements in other matrices, even non-conductors.

LIBS - Laser-Induced Breakdown Spectroscopy - and TRELIBS - Time REsolved Laser-Induced Breakdown Spectroscopy - are relatively new techniques for obtaining analytical emissions from solid, liquid and gaseous samples. A pulsed laser is focused on the surface of a solid or liquid sample or focused in a gaseous sample, creating a transient plasma. Sample analytes emit characteristic radiation for upwards to tens of micro-seconds. The event is monitored spectrophotometically using LIBS, where the whole event is analyzed, or by TRELIBS, where the time resolution of the plasma event is analyzed.

The properties of coherent anti-Stokes Raman spectroscopy (CARS) which make it an attractive, spatially and temporally precise, non-intrusive laser diagnostic technique for the remote probing of practical combustion devices are reviewed. The application of CARS to practical devices demands consideration of some limits and interferences which may exist. Recent advances in the engineering of CARS for these applicatons are reviewed.

Light-scattering techniques that are useful for the in situ measurement in flames of particles smaller than 0.1 μm are reviewed. Included are a summary of the properties of small particles in flames, a basic description of static- and dynamic-light-scattering measurement techniques, and selected examples that demonstrate the application of these techniques in flame environments.

Fluorescent dopants which allow the two-dimensional, real-time, non-intrusive visualization of vapor/liquid concentrations and droplet temperatures in hydrocarbon fuel sprays have been demonstrated. These systems, which are based on the photophysics/chemistry of organic exciplexes (excited state complexes), when coupled with planar laser excitation and electronic array detectors, should make possible the development of engineering test rigs for the evaluation of spray nozzles. Two organic compounds are added to the hydrocarbon fuel, a fluorescent monomer M and an appropriately chosen ground state reaction partner G. Electronically excited M may react with G to form the exciplex E* according to the following reaction: M* + G <==> E* In the vapor/liquid visualization studies, the equilibrium is adjusted so that the M* emission is a marker for the fuel vapor and the E* emission, which is red-shifted from the M* emission, is a marker for the liquid. In the temperature visualization studies, the temperature dependence of the M*/E* ratio is used to determine the droplet temperatures. Preliminary studies on fuel sprays of hexadecane, showing the liquid and vapor phases separately, will be presented. Exciplex-based thermometer systems applicable to temperatures as high as 400°C will be discussed.

Spontaneous Raman scattering has been applied at the Combustion Research Facility of Sandia National Laboratories to study high-temperature reactions at the gas-solid interface. This technique provides information otherwise unobtainable concerning phases and structures present on surfaces at elevated temperatures. We discuss three representative applications, oxidation of alloys, formation of deposits, and ceramic attack by molten salts.

The U.S. Geological Survey through a contract with the Charles Stark Draper Laboratory has developed the Aerial Profiling of Terrain System. This is an airborne inertial surveying system designed to use a laser tracker to provide position and velocity updates, and a laser profiler to measure terrain elevations. The performance characteristics of the system are discussed with emphasis placed on the performance of the laser devices. The results of testing the system are summarized for both performance evaluation and applications.

A remote sensing technique is theoretically developed whereby the temporal frequency spectrum of the scintillations of a stellar source or a point source within the atmosphere, observed through a variable radius aperture, is related to the space-time spectrum of atmospheric scintillation. The key to this spectral remote sensing method is the spatial filtering performed by a finite aperture. The entire method is developed without resorting to a priori information such as results from stochastic wave propagation theory. Having obtained the space-time spectrum of scintillations, an application of known results of atmospheric wave propagation theory and simple geometric considerations are shown to yield information such as the spectrum of atmospheric turbulence, the path averaged cross-wind velocity, and the path profile of the atmospheric refractive index structure parameter. The success of this proposed remote sensing method relies on the solution to a Fredholm integral equation of the first kind. A solution is obtained and a proof is given demonstrating the well-posedness (in the sense of Hadamard) of this inverse problem.

The Polar Platform is a planned element of the NASA Space Station program, currently envisaged to be implemented in the early 1990's. The term "Polar Platform" actually encompasses a fleet of platforms in sunsynchronous, near-polar orbit. The list of potential users, or payloads, for these platforms includes NASA's Earth Observing System (Eos), the National Oceanic and Atmospheric Administration's (NOAA) operational instruments, international and commercial interests, with NASA and NOAA payloads being the best defined and the most dominant users at this time. The Polar Platform will enable a multidisciplinary, long term mission life approach to future Earth science measurements by the provision of sufficient payload resources (mass, power, data handling, etc.) to support a large suite of future Earth remote sensing instrumentation, and by the planned servicing capability via the Shuttle for instrument and subsystem repair, replacement, enhancement, refurbishment and calibration. This will allow the generation of long term Earth science data sets for application to studies in the fields of agriculture, forestry, geology, hydrology, oceanography, snow and ice, atmospheric chemistry, and atmospheric dynamics, and will eventually lead to an understanding of the global hydrologic cycle, global biogeochemical cycle, and global climate processes.

The concept of the Imaging Spectrometer is becoming established as a major new thrust in remote sensing' of the earth. Aircraft instruments are in operation and under construction, and a Shuttle Flight experiment is planned for 1991. This paper will describe the application of the concept to an instrument for the Earth Observing System (EOS), including some of the major technical challenges.

Plans are underway at NASA/Goddard Space Flight Center to develop a moderate resolution (0.5-1.0 kilometer) imaging spectrometer with 104 spectral bands in the range from 0.4 to 14.2 micrometers for use as a NASA facility aboard the Earth Observing System (EOS). Science requirements call for the system to image the Earth's surface every 2 days for a period in excess of 10 years. Numerous and diverse tasks in the areas of terrestrial, oceanic, and atmospheric science require two electro-optical sensors. MODIS-T (tilt) is a sixty-four channel imaging spectrometer with 10-nanometer wide channels in the 0.4-1.0 micrometers spectral range. The system has 5 centimeter diameter optics, scans ±45°, and can be pointed in the range ±60° along track. Calculated S/N is in excess of 800:1 near 0.4 micrometers. MODIS-N (nadir) is a 40-channel imaging spectroradiometer that scans ±45° about nadir with twelve 500 meter and twenty-eight 1000 meter resolu-tion channels including two polarization channels and fourteen thermal infrared channels. With 20 centimeter diameter optics, the calculated S/N's of the majority of the reflected solar bands are over 1000:1. NETD for the thermal bands are on the order of 0.1-0.2 K at 300 K. Combined MODIS-T and MODIS-N data rates are 8.3 megabits per second in daylight, 1.5 megabits per second at night resulting in a total of 3.6 x 10¹¹ bits per day.

The evolution of the Spaceborne Imaging Radar (SIR) has lead to a multipolarization, multifrequency synthetic aperture radar (SAR) with variable imaging geometry which will be ready for flight on the Earth Observing System (Eos). Nominally, this SAR will be a three frequency (L-, C- and X-bands) system with quadpolarization available for the L- and C-bands. It will be capable of acquiring multiincidence angle data using electronic beam steering and other imaging geometries by mechanically pitching, yawing and rolling the antenna. The capabilities of the Eos SAR, particularly acquisition of cross polarized and high incidence angle data, depend on the altitude of the platform on which the SAR flies and improve significantly at lower altitudes. The Eos SAR will provide a unique new data set and will play a key role in understanding the Earth's global processes alone and synergistically with other Eos instruments.