An optical-particle sensor head comprises an electromagnetic radiation source to transmit electromagnetic radiation toward the detection chamber; one or more baffles, between the light source and the detection chamber, to restrain a spread of the electromagnetic radiation from the electromagnetic radiation source; and at least two off-angle photo-sensors.

Methods and systems suitable for tracking Brownian motion of particles suspended in a fluid and determining the diffusion coefficient of the particles therefrom in order to characterize the particles, their synthesis, and/or their surface modifications. The methods include providing a sample having particles suspended in a fluid, obtaining and recording at least first and second images of the sample wherein the first image obtained at a first time and the second image subsequently obtained at a second time, determining the average displacement of the particles in an area of the first and second images during a time period between the first time and the second time based on the first and second images, and then determining a diffusion coefficient of the particles in the area of the first and second images based on the average displacement of the particles during the time period.

A particle detector, e.g. a smoke detector is described. In one form the detector includes a detection chamber and radiation source emitting a single beam of radiation. The detector also includes a radiation receiving system and an imaging system arranged to receive radiation from a common region of interest. Methods and systems for analysing the output of a particle detector are also disclosed.

A particulate matter sensor device comprises an enclosure (21) defining a flow channel (2), a radiation source (3) for emitting radiation into the flow channel for interaction of the radiation with particulate matter in an aerosol sample in the flow channel, and a radiation detector (4) for detecting at least part of said radiation after interaction with the particulate matter. The sensor device comprises a flow modifying device (511) arranged upstream of the radiation detector and/or radiation source so as to reduce particulate matter precipitation onto the radiation detector, the radiation source and/or the channel wall sections in their proximity. The invention also relates to a method of determining parameters of particulate matter in an aerosol sample by using such a particulate matter sensor device.

A method for characterizing particle objects comprises generating a radiation beam, illuminating with the radiation beam an observation region transited by a particle object, collecting an interference image determined by an interference between a transmitted fraction and a part of the scattered fraction of the radiation beam that propagates around the direction of the optical axis, collecting a part of the scattered fraction that propagates at the scattering angle, and measuring at least one scattered radiation intensity value determined by the part of the scattered fraction, calculating, from the interference image, a pair of independent quantities that define the complex field of the first part of the scattered fraction, calculating, starting from the pair of independent quantities, a theoretical value of scattered radiation intensity, and comparing the measured value with the theoretical scattered radiation intensity value.

A method and apparatus for particle counting and wavelength or angle performed in combination in order to characterize an aerosol is disclosed. In one example, data regarding particle counting (such as from an optical particle sensor) and data regarding angle or wavelength (such as from an ensemble measurement sensor) may be separately generated, with the separately generated data being analyzed in combination in order to characterize the aerosol. In another example, data regarding particle counting and regarding angle or wavelength may be generated in combination in order to characterize the aerosol.

A particle detector, e.g. a smoke detector is described. In one form the detector includes a detection chamber and radiation source emitting a single beam of radiation. The detector also includes a radiation receiving system and an imaging system arranged to receive radiation from a common region of interest. Methods and systems for analysing the output of a particle detector are also disclosed.

A method for determining a parameter of a particle present in a sample, the method comprising the following steps: a) illuminating the sample with the light source, the light source emitting an incident light wave that propagates along a propagation axis; b) acquiring an image of the sample with the image sensor, the image sensor being exposed to an exposure light wave; c) determining a position of the particle in the detection plane; d) on the basis of the acquired image, applying a propagation operator, for a plurality of distances from a detection plane, so as to estimate, at each distance, a complex amplitude of the exposure light wave; e) on the basis of the complex amplitude estimated, at various distances, obtaining a profile representing a variation of the complex amplitude of the exposure light wave along an axis parallel to the propagation axis and passing through the position of the particle.

The particle may associated with a set of parameters, comprising at least a size of the particle and a refractive index of the particle.

The invention provides an optical particle sensor which uses light sources of different first and second wavelengths. A first light source is used to detect light scattering and also to determine when a particle reaches a target positional area. In response to the particle being determined to reach the target positional area, a second light source is operated to provide a pulse of light, and light emitted from the particle in response to the pulse of light is detected by the same detector.

A particulate matter sensor module includes a light source and a light detector mounted on a substrate. A housing is attached to the substrate and includes first and second sections attached to one another in a stack over the substrate such that the first section is disposed between the substrate and the second section. The first and second sections, in combination, define a light reflection chamber, a fluid flow conduit, a particle-light interaction chamber, and a light trap chamber. The first section has a first aperture through which light emitted by the light source can pass to a reflective surface within the light reflection chamber. The reflective surface is configured to reflect the light toward the particle-light interaction chamber where the light can interact with particles in a fluid flowing in the fluid flow conduit. The first section has a second aperture through which light scattered in the particle-light interaction chamber as a result of interaction with one or more of the particles can pass for sensing by the detector. The fluid flow conduit includes a fluid inlet portion having an end coupled directly to the particle-light interaction chamber.