Particle detector, system and method

1. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image; and

comparing the recorded intensity with a recorded intensity at a previous time,

wherein the previous time is a time of installation.

2. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time; and

estimating particulate density based on said path loss measurement.

3. A method as claimed in claim 2 , wherein the first beam of radiation is a laser beam and the first image capturing device is a camera, and said method includes: providing a laser target on which the laser beam forms the target incident beam spot.

4. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time; and

using the path loss measurement in conjunction with scattering information to estimate mean particle density.

5. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time; and

using the path loss measurement in conjunction with scattering information to discriminate particle type.

6. A method as claimed in claim 5 , wherein discrimination between particle types includes computing a ratio of path loss to scatter and comparing the ratio to ratios for known material.

7. A method as claimed in claim 5 , wherein said discrimination is performed over either a segment of the beam or the whole beam.

8. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time;

providing a second emitted beam having its source adjacent and at an angle to a second image capturing device such that the second beam crosses the field of view of the second image capturing device; and

detecting backscattered light from the monitored region.

9. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image; and

comparing the recorded intensity with a recorded intensity at a previous time,

wherein the detected backscattered light has an angle of scattering of any one or more of:

about 180° with respect to the emitted beam direction;

slightly less than 180 degrees to the beam direction; and

greater than 90 degrees.

10. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time; and

detecting a variation in images of the region such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to forward scattered radiation.

11. A method as claimed in claim 10 , further comprising either or both of:

emitting another beam of radiation into the monitored region to enable the detection of particles using forward scattered radiation; and

detecting a variation in images of the region with a second image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to forward scatted radiation.

12. A method of detecting particles comprising:

emitting a first beam of radiation into a monitored region;

detecting a variation in images of the region with a first image capturing device such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to backscattered radiation;

determining a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured image;

comparing the recorded intensity with a recorded intensity at a previous time;

providing edge detection and correlation of the captured image to determine whether there has been physical movement of a beam and image capture device; and

providing Image processing to determine movement of a target marker in the captured image beyond a threshold alarm level to thereby determine whether there has been physical movement of a beam and image capture device; and

providing an additional source of emitted radiation into the monitored region to provide markers for the image capture device to thereby determine whether there has been physical movement of a beam and image capture device pair.

13. A particle detection system comprising:

a light source emitting a first beam of radiation into a monitored region; and

a first image capturing device configured to detect a variation in images of the region such that the variation in images indicates the presence of the particles and wherein the light source and first image capturing device are arranged such that the variation in images corresponds to backscattered radiation;

the particle detection system being further configured to:

determine a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured images

compare the recorded intensity with a recorded intensity at a previous time; and

further comprising:

a second image capturing device arranged to capture images of the region with such that the variation in images indicates the presence of the particles and wherein the variation in images corresponds to forward scatted radiation.

14. A particle detection system as claimed in claim 13 , wherein the light source comprises a laser which emits a laser beam and the system further includes a laser target on which the laser beam forms a target incident beam spot.

15. A particle detection system comprising:

a light source emitting a first beam of radiation into a monitored region; and

a first image capturing device configured to detect a variation in images of the region such that the variation in images indicates the presence of the particles and wherein the light source and first image capturing device are arranged such that the variation in images corresponds to backscattered radiation;

the particle detection system being further configured to:

determine a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured images;

compare the recorded intensity with a recorded intensity at a previous time; and

further comprising:

a second beam of radiation emitted into the monitored region to enable the detection of particles using forward scattered radiation.

16. A particle detection system comprising:

a light source emitting a first beam of radiation into a monitored region; and

a first image capturing device configured to detect a variation in images of the region such that the variation in images indicates the presence of the particles and wherein the light source and first image capturing device are arranged such that the variation in images corresponds to backscattered radiation;

the particle detection system being further configured to:

determine a path loss measurement by recording the intensity of a target incident beam spot of the emitted first beam within the captured images;

compare the recorded intensity with a recorded intensity at a previous time; and

further comprising:

a light source emitting a second emitted beam, said source being arranged adjacent and at an angle to a second image capturing device such that the second beam crosses the field of view of the second image capturing device.

17. A method as claimed in claim 5 , wherein the first beam of radiation is a laser beam and the first image capturing device is a camera, and said method includes: providing a laser target on which the laser beam forms the target incident beam spot.

18. A particle detection system as claimed in claim 15 , wherein the light source comprises a laser which emits a laser beam and the system further includes a laser target on which the laser beam forms a target incident beam spot.