Abstract: The present invention relates to an apparatus and method of determining particulate integrated properties consisting of integrated volume concentration, integrated surface area concentration and aerosol extinction coefficient in the infrared portion of the light spectrum using a noncollimated light beam irradiating suspended particulates. A light trap is placed in front of the lens that collects the light scattered by the particulates. Two separate detectors are placed differently with respect to the noncollimated beam to measure the light scattered by the particulates. Variable transmission filters are placed in front of the detectors to correct for the distortions in the light scattered by the particulates due to the off-axis intensity of the noncollimated beam.

Abstract: An apparatus for determining the liquid water content (LWC) of a sample gas aving water droplets suspended therein includes a light source for passing a collimated light beam through the sample gas, and a sensor for detecting the light scattered by the water droplets. The sensor includes a photodetector having a planar light sensitive surface positioned to receive scattered light. A light trap is also provided between the photodetector and the light source for blocking nonscattered light in the light beam from the photodetector. The light flux detected by the photodetector is proportional to LWC.

Abstract: A nephelometer and method for measuring optical quality of a marine atmosphere and particularly characterizing its aerosol particle size distribution, visual range and aerosol optical effects in the visible and infrared. There is provided a housing for entrapping a momentary aerosol sampling, a laser source for providing a narrow collimated beam of radiant energy (usually light) through the sample, and plural spaced-apart cosine sensors facing across the radiant energy illuminated sample, with one reading a slightly greater angle than the other, for receiving aerosol particle scattered light. Integrated outputs from the sensors when compared with laser output intensity as a reference signal provide an indication of aerosol particle size distribution and concentration.

Abstract: A supersaturation hygrometer formed by a thermo-optical servo system which esponds to water vapor changes in the range just above and below water saturation. The system includes a hydrophobic metal chip on which monodisperse submicron salt particles act as centers of water condensation. A change in scattered light from the solution droplets on the chip drives an infrared source which heats the chip to keep the size of the droplets constant. The infrared power is related to the chip ambient temperature difference which is proportional to the ambient water vapor pressure.