Abstract: According to example configurations herein, a fluid sample flow including particulate matter passes through a conduit. One or more optical sensors monitor optical energy scattering off of the particulate matter in the fluid sample flow as it passes through the conduit. A magnitude of the optical energy sensed by the one or more optical sensors varies depending on particulate matter present in the fluid sample flow. An analyzer monitors the magnitude of the optical energy sensed by the one or more optical sensors and detects changes in the optical energy. A change in the optical energy can indicate a change in the particulate matter present in the fluid sample flow. In response to detecting the change in the optical energy, the analyzer initiates one or more functions such as recalibration, purging, execution of diagnostics, etc.

Abstract: According to example configurations herein, a fluid sample flow including particulate matter passes through a conduit. One or more optical sensors monitor optical energy scattering off of the particulate matter in the fluid sample flow as it passes through the conduit. A magnitude of the optical energy sensed by the one or more optical sensors varies depending on particulate matter present in the fluid sample flow. An analyzer monitors the magnitude of the optical energy sensed by the one or more optical sensors and detects changes in the optical energy. A change in the optical energy can indicate a change in the particulate matter present in the fluid sample flow. In response to detecting the change in the optical energy, the analyzer initiates one or more functions such as recalibration, purging, execution of diagnostics, etc.

Abstract: The present disclosure has an apparatus for detecting fibers in a gas flowing along a passageway. A laser beam is provided at one end of the passageway and the beam is directed along a length of the passageway through which the gas flows. An electrode system, as disclosed, a quadrupole electrode system is mounted along the passageway to cause fibers carried in the gas to oscillate in a detection zone. A photo detector is positioned laterally of the passageway and detects light scattered by the oscillating fibers and projected through an opening in the passageway to provide an output signal that is a function of the light scattered by the fibers in the detection zone.

Abstract: A particulate mass monitor includes a controller that monitors a change in a resonant oscillation frequency of a taut metallic membrane, as caused by deposition of the particulate matter on the metallic membrane. The metallic membrane, such as a foil or metallized plastic film, is substantially mechanically stable under tension. Application of a tension to the periphery of the metallic membrane generates a substantially constant tension within the membrane, thereby allowing the particulate mass monitor to detect a particulate mass concentration of the air sample with a relatively high degree of accuracy. Additionally, the particulate mass monitor includes a membrane transporter that automatically advances the metallic membrane within the particulate mass monitor. The membrane transporter minimizes the necessity for manual replacement of the metallic membrane over time and allowing long term, unattended operation of the particulate mass monitor.

Abstract: A particulate mass monitor includes two mass sensors, such as an optical sensor (e.g., a light scattering photometer or nephelometer) and a beta radiation attenuation sensor for substantially continuous monitoring of ambient particulate matter. During operation, the first mass sensor references the time-averaged measurement of the second mass sensor such that the second mass sensor calibrates the response of the first mass sensor. If the first sensor is an optical sensor, as it detects the presence of particulate matter within a fluid, the mass concentration measurement (e.g., signal output) provided by the optical sensor is altered using a ratio of concentration measurements of the second mass sensor and the optical sensor. The combined use of the two mass sensors provides accurate mass measurements of ambient particulate matter with a relatively high time resolution.

Abstract: System for, and method of, monitoring airborne particulate, including particulate of the PM.sub.2.5 class. The system for monitoring airborne particulate includes an optical sensor to measure size characteristics of sampled airborne particulate and a humidity sensor to measure relative humidity. An adjusted airborne concentration value is then produced in response to the measured size characteristics and to the humidity measurement. According to one embodiment the optical sensor is implemented as a multi-wavelength nephelometer, e.g., two-wavelength nephelometer. According to another embodiment the humidity sensor is placed relatively near the optical sensing region and makes a relative humidity measurement.

Abstract: A system and method for measuring particulate concentrations. The system includes a substantially planar, peripherally supported filter for capturing the particulates, an oscillator for oscillating the filter substantially perpendicular to its planar surface, and a sensor for measuring the frequency of oscillation.

Abstract: A system and method for determining airborne particle concentrations. When in a fixed time period mode of operation, the system determines actual airborne particle concentration when a normal particle count is detected, and determines an "upper limit" particle concentration based on Poisson statistics when a low particle count is detected. In a fixed precision mode of operation, the system determines in advance the number of particles needed to be detected to achieve an airborne particle concentration measurement having a precision equivalent to a user selected fixed precision, and prints out airborne concentration measurements only when such measurements have the user selected fixed precision.

Abstract: A real time asbestos aerosol monitor and method are provided. An ambient air sample is passed through a first sensing zone where fibers in the sample are electrically aligned and oscillated as they are illuminated perpendicular to the fiber axes with high intensity laser light. The scattered light signal pulse train from a first detector is analyzed to determine the presence and size of fibers in the sample. The air sample is then passed through a second sensing zone including a hybrid electric/magnetic field to electrically align and magnetically oscillate asbestos fibers. The sample in the second sensing zone is illuminated perpendicular to the fiber axes, with the scattered light signal pulse train from a second detector being analyzed to determine whether each fiber detected in the first sensing zone is an asbestos fiber. Advantageously, clean air is circulated across illumination optical surfaces to protect against abrasive elements in the air sample. Zeroing and calibration are also provided.

Abstract: A system for automatically detecting dust or other minute particles on a large-area, optically unpolished surface such as a face of a glass reticle plate used in the production of microelectronic circuits. The system irradiates the surface with a narrow, high intensity beam of monochromatic radiation at a grazing angle, typically 1/2 degree with respect to the surface. An oscillating mirror scans the beam across the moving surface in a direction generally perpendicular to the direction of plate advance. A beam splitter provides separate inspecting beams for each surface of the plate. Optical systems characterized by a high numerical aperture are positioned on opposite sides of the plate to collect radiation which is scattered from the particles. The optical systems are oriented to accept scattered radiation, and typically have their optical axes at an angle in the range of 60.degree. to 160.degree. measured from the direction of advance.

Abstract: In the smoke opacity monitor disclosed herein, a measurement of opacity is obtained by measuring the proportion of polarized light from the background sky which is detectable through the smoke plume. Compensation and normalization is provided to minimize errors generated by illumination of the plume itself and for the overall intensity of the background sky light.