Abstract: Systems and methods for spectral imaging are disclosed. Such spectral imaging can be used to determine properties of a subject material at different locations upon the surface and/or within the material. For example, strain and/or stress within an imaged area of the material can be determined. A system for spectral imaging can include a light source, a two-dimensional sensor array configured to image light from a two-dimensional area of a subject material, a filter configured to filter light from the subject material before the light is imaged and a processor in communication with the two-dimensional sensor array. The processor can be configured to determine a property of the subject material at a plurality of locations within the two-dimensional area of the subject material. Such spectral imaging systems can facilitate the performance of piezospectroscopic measurements of two-dimensional surfaces in a rapid manner while preserving accuracy.

Abstract: This system measures the speed of an airborne vehicle relative to the surrounding atmosphere. The measurement is based on the scattering of pulses of coherent laser radiation, generated in the vehicle, preferably in the infrared region of the electromagnetic spectrum, by particles naturally present in the atmosphere at all times. The pulses are focused into the atmosphere at a sufficient distance from the vehicle, preferably 10-30 meters, to be beyond that region perturbed by the passage of the vehicle. The frequency of the radiation scattered by the particles differs from the frequency of the transmitted pulses by virtue of the relative motion of the vehicle and the atmosphere. Equipment in the vehicle digitally processes the received energy to determine this frequency difference for each pulse, and hence the component of the vehicle's velocity in the direction of the pulse transmission.

Abstract: A source produces light, preferably in a wavelength band of approximately 185-200 nm and in pulses at a suitable frequency (e.g., 100 Hz). The light may be directed in a progressively diverging beam into the atmosphere for a Rayleigh scattering by molecules in the atmosphere in the 185-200 nm wavelength band and for fluorescence by particular molecules (e.g. oxygen) in the atmosphere in another wavelength band (e.g. 210-260 nm). The Rayleigh scattered light and the fluorescent light may pass in a progressively converging beam to two detectors, one responsive to the Rayleigh scattered light to produce first signals and the other responsive to the fluorescent light to produce second signals. Optical elements may prevent the second detector from responding to the fluorescent light and the second detector from responding to the scattered Rayleigh light. A data processor processes the first and second signals to provide outputs representative of the atmospheric pressure and temperature.

Abstract: A plurality of lasers, each regulated to operate at a particular temperature, are supported by a manifold to direct coherent light into space. The regulation may be provided by producing pulses of a trickle current of a particular magnitude through the laser, measuring the voltage required to produce the trickle current and adjusting the characteristics of a thermoelectric member in accordance with the magnitude of such voltage to adjust the rate at which the thermoelectric member transfers heat from the laser. The lasers produce substantially parallel and thin beams of light in pairs. The light beams in each pair provide an optimum angle for the interception by such paired beams of particles having individual trajectories in space. These particles scatter the light to a receiving lens system disposed within the manifold. The received light then passes through masks which restrict the collected light to a spatial pattern corresponding to the pattern of the light beams from the lasers.