Particle detection
View Patent ↗A particle detection system ( 100 ), such as an active video smoke detection system, includes at least one illumination means ( 102 ) for directing a beam ( 106 ) of radiation through at least part of the air volume being monitored ( 110 ), an image sensor ( 104 ) is positioned to capture images of at least part of a beam ( 106 ) from illumination means ( 102 ); and means to analyze ( 107 ) the captured images to detect the presence of particles within the volume. At least 29 different aspects are described for improving the sensitivity, usability, and robustness of particle detection. These include, for example, configuring illumination means ( 102 ) to create a curtain of light or a rapidly-scanned beam across the air volume ( 110 ), and configuring a reflector to steer or change direction of a beam reflected from illumination means ( 102 ).
1. A method of determining alignment of a beam in an AVSD system, the method including:
emitting a beam of light across a volume being monitored;
scanning the beam of light across a predetermined area;
receiving at least a portion of the beam of light at a light sensor; and
based on at least one measured parameter of the received light determining an alignment of the beam of light; and
based on the determined alignment, changing the alignment of the beam so that the beam is aligned in a predetermined manner.
2. A method as claimed in claim 1 wherein the measured parameter includes any one or more of the following characteristics:
light intensity, spot size, total received irradiance, a light intensity pattern.
3. A method as claimed in claim 1 wherein the method additionally includes:
reflecting at least a portion of the light beam from a reflector, back toward a light sensor such that either the emitted beam or reflected beam traverse the volume being monitored.
4. A method as claimed in claim 3 wherein the method includes the step of: analysing the light received as a result of scanning of the beam to identify a light reception pattern characteristic of a reflection from a reflector forming part of the AVSD system.
5. A method as claimed in claim 4 wherein the optical characteristics of the reflector include means for forming a detectable pattern in light reflected from the reflector caused by a reflectivity, refraction and/or diffraction characteristic of at least part of the reflector.
6. A method as claimed in claim 1 wherein the step of scanning the beam of light across a predetermined area includes scanning the beam in a predetermined pattern.
7. A method as claimed in claim 6 wherein the pattern includes any one or more of the following patterns;
a linear patter, a raster pattern, a spiral pattern.