Described herein are apparatus and methods for orthographic imaging of particles. Particularly, a method to obtain contact-free images of aerosol particles with digital holography from three orthogonal directions is described and demonstrated. Diode lasers of different wavelengths simultaneously illuminate free flowing particles to form holograms on three sensors. Images of the particles are reconstructed from the holograms and used to infer the three-dimensional structure of single spherical particles or clusters of sphere-like particles. The apparatus employs inexpensive components and requires no lenses to achieve the imaging, which gives it a large sensing volume and simple design.

An airborne, gas, or liquid particle sensor with multiple particle sensor blocks in a single particle counter. Each sensor would sample a portion of the incoming airstream, or possibly a separate airstream. The various counters could be used separately or in concert.

The invention relates to a method for determination of ambient mineral dust concentration based on optical absorption of particles concentrated by a virtual impactor as well as a device performing the said method. The method comprises the following steps: Sampling air samples with particle size smaller than 1 μm (PM.sub.1) and sampling air samples with particle size up to 10 μm; Concentrating the samples with particle sizes up to 10 μm with a virtual impactor; Measuring optical absorption of collected samples at least one wavelength from UV to IR spectre, preferably from 370 to 950 nm, most preferably at 370 nm; Subtracting the absorption of the samples with particle size smaller than 1 μm from the absorption of the sample concentrated by the virtual impactor.

A photo-electric smoke detector assembly includes a Y-shaped optic block with a first photo-electronic device mounted on a first end and second and third photo-electronic devices mounted on a second end, with an interaction volume at a midpoint. Two of the photo-electronic devices direct pulses of differing wavelengths toward the interaction volume, and the remaining photo-electronic device receives light from the pulses scattered off of smoke particles in the interaction volume.

Techniques for monitoring particulate matter (PM) mass concentration using relatively low cost devices are described. A computer-implemented method comprises determining, by a device operatively coupled to a processor, relationships between: first PM mass data determined by a monitor station device for a first atmospheric area over a period of time; first PM count data determined by a reference PM count device for the first atmospheric area over the period of time; and first conditional information comprising first values for defined conditional parameters, wherein the first values are associated with the first atmospheric area over the period of time. The method further includes generating an initial conversion model based on the relationships, wherein the conversion model converts a PM count to a PM mass based on one or more conditional parameters of the defined conditional parameters and features for updating the conversion model.

A method for determining a source-dependent particle size distribution of an aerosol by an aerosol measuring device. First, a fraction parameter is determined that corresponds to a fraction of a source-dependent aerosol part of the aerosol. In addition, a particle size distribution of the aerosol particles is determined such that the source-dependent particle size distribution of the aerosol is determined from the fraction parameter and the particle size distribution. In terms of the device, the invention comprises an aerosol measuring device for determining a source-dependent particle size distribution of an aerosol, by means of which aerosol measuring device a fraction parameter can be determined that corresponds to a fraction of a source-dependent aerosol part of the aerosol. A particle size distribution of the aerosol particles can be determined such that the source-dependent particle size distribution of the aerosol can be determined from the fraction parameter and the particle size distribution.

A particle measurement system and method of operation thereof are described. The system and method render a characteristic for a set of particles measured while passing through a measurement volume. The system includes a source that generates a particle-laden field containing the set of particles. The system further includes a sensor that generates a raw particle data corresponding to the set particles passing through the measurement volume of the particle measurement system, where the raw particle data comprises a set of raw particle records and each of one of the raw particle records includes a particle data content. A preconditioning stage carries out a preconditioning operation on the particle data content of the set of raw particle records to render a conditioned input data. A machine learning stage processes the conditioned input data to render an output characteristic parameter value for the set of particles.

A fine particle measuring device performing fine particle measurement includes a particle probe, a pipe connected to the particle probe, and a particle counter connected to the pipe. A cylindrical pipe is disposed on an outer periphery of the pipe and an air flow path is provided between the pipe and the cylindrical pipe.

A system comprises a particle sensor unit in communication with a processor. The sensor unit comprises a source that transmits light into an interrogation region; receive optics that collect scattered light from particles in the interrogation region; and an optical detector that receives the collected light from the receive optics. The detector comprises a sample area including one or more sampling pixels, and an edge region including one or more edge pixels. The processor analyzes intensity data from the detector by a method comprising: combining all intensity data from the sampling pixels; adding the combined intensity data to a data set; determining whether to accept overlap intensity data that corresponds to an overlap between the sampling pixels and the edge pixels; adding the overlap intensity data to the data set if accepted; discarding the overlap intensity data if not accepted; and discarding all non-overlapping intensity data from the edge pixels.

A particulate matter sensing device includes an inlet through which air is introduced, a particle classifying unit classifying particles included in air introduced through the inlet, a corona discharging unit electrifying the particles passing through the particle classifying unit, and a sensing unit collecting the particles electrified by the corona discharging unit, in which the sensing unit includes an electrode having a plurality of intervals to collect the particles electrified by the sensing unit, and a control unit determining whether fine particles are detected, based on a result of monitoring an output signal change of the electrode.