Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size.

Abstract: An optical probe for analyzing a sample illuminated by a laser includes an input optical fiber operably connectable to the laser where the input optical fiber has an entrance end and an exit end. The probe also includes a first beam splitter where the first beam splitter is adapted to transmit an alignment portion of a light beam from the input fiber exit end and to reflect a homodyning portion of the light beam from the input fiber. The probe also includes a lens between the input fiber exit end and the first beam splitter and a first and a second output optical fiber, each having an entrance end and an exit end, each exit end being operably connectable to respective optical detectors. The probe also includes a second beam splitter which is adapted to reflect at least a portion of the reflected homodyning portion into the output fiber entrance ends and to transmit light from the laser scattered by the sample into the entrance ends.

Abstract: An interferometer having a light beam source that produces a plurality of separate and distinct wavelengths of light. Optic fibers are used to transport the wavelengths of light toward an object surface and to allow light reflected from the object to pass through a polarizer to improve the polarization ratio of the reflected light to determine a characteristic of the object surface.

Abstract: A method and apparatus for analyzing a fluid containing light scattering components. The apparatus includes a laser adapted to direct abeam of light into the fluid such as a liquid containing particles, and at least two detectors to receive light scattered by the fluid, which received light is used to calculate a physical property of the fluid. A focusing lens may be used to focus the light beam to a focal waist in the fluid to enhance the degree of spatial coherence of the scattered light. The two detectors are aligned onto the focal waist and are adapted to send a signal to a data processor which correlates the signal received from said two detectors. The two detectors are spaced a substantially equal distance from the focal waist and are oriented at substantially the same angle with respect to the direction of propagation of the incident beam. The data processor is adapted to cross-correlate the signals received from the two detectors.

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 laser package includes a laser with first and second spaced terminals and a layer between the terminals with properties of emitting light when voltage pulses are applied between the terminals. A current of a particular magnitude is produced between the terminals in the time periods between the voltage pulses. The voltage required to produce such current is dependent upon the layer temperature. Variations in this voltage produce variations in the rate of pulses from a thermoelectric cooler included in the laser package. Variations in the rate of such pulses from the thermoelectric cooler affect the rate at which heat is withdrawn by the thermoelectric cooler from the laser. A cooler body is disposed adjacent to the thermoelectric member and is constructed to pass a cooling fluid through the cooler body to cool the thermoelectric member. The cooling fluid passes through an inlet port to a plurality of channels converging at a central recess.

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.

Abstract: Light from a moving airborne vehicle and scattered from atmospheric particles produces at first and second detectors at the vehicle, signals which are spatially and spectrally filtered, and conditioned by amplification and special filtering and converted to digital signals. The digital signals are edited and accepted if they satisfy certain conditions pertaining to a threshold variable with the average amplitude level of the noise plus signals. The digital signals from each particle are grouped. A centroid, based upon a weighting of the signals in each group with amplitude and time, is determined to represent the most probable time at which the particle crossed the peak of the illuminated region. The peak amplitude of each signal from the first detector is paired with the peak amplitude of the successive signals from the second detector. The time difference between the paired signals, and their product amplitudes, are determined.

Abstract: Apparatus for laser anemometry comprises a device for producing coherent radiation, a beam splitter device adapted to divide the beam from this device into two beam portions, focussing means adapted to focus these two beam portions on to two adjacent spots, and two photodetector means each adapted to measure the scattered illumination from one said spot. In order to enable the direction of the path between the two spots to be altered without moving the entire apparatus, an image rotation device is provided and mounted to effect both the beam portions and the scattered radiation from the spots which falls on the photo-detector means.