US 12,313,518 B2
Device for measuring the quality of air
Samuli Lintonen, Vantaa (FI); and Mikko Halonen, Espoo (FI)
Assigned to SAFERA OY, Espoo (FI)
Appl. No. 17/640,103
Filed by SAFERA OY, Espoo (FI)
PCT Filed Sep. 4, 2020, PCT No. PCT/FI2020/050570
§ 371(c)(1), (2) Date Mar. 3, 2022,
PCT Pub. No. WO2021/044080, PCT Pub. Date Mar. 11, 2021.
Claims priority of application No. 20195735 (FI), filed on Sep. 6, 2019; application No. 20195736 (FI), filed on Sep. 6, 2019; application No. 20195738 (FI), filed on Sep. 6, 2019; and application No. 20195739 (FI), filed on Sep. 6, 2019.
Prior Publication US 2022/0291110 A1, Sep. 15, 2022
Int. Cl. G01N 15/1434 (2024.01); G01N 15/00 (2024.01); G01N 15/14 (2024.01)
CPC G01N 15/1434 (2013.01) [G01N 15/1459 (2013.01); G01N 2015/0046 (2013.01); G01N 2015/1452 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A device for measuring the particle content of air, the device comprising:
a laser source for generating laser light and for directing it to a target area,
an air channel for directing the air subjected to the measurement as an air flow through the target area,
a light detector located adjacent to the target area for detecting bursts of light generated as the particles entrained with said air flow scatter said laser light in the target area, and
a light trap between said laser source and said target-area air channel for reducing stray light propagating to the target area, the light trap comprising at least two intermediate walls which are substantially transverse in relation to the propagation direction of said laser light, each of the intermediate walls having an aperture for passage of a desirably limited amount of the laser light through the given intermediate wall, wherein
said at least two intermediate walls are part of a same piece manufactured as one continuous block, such that each of said apertures is delimited along the full perimeter of the aperture by a continuous portion of said piece manufactured as one continuous block,
said at least two intermediate walls include a first intermediate wall and a second intermediate wall, located in this order from the laser source towards the air channel,
the aperture in the first intermediate wall is conical in a cross-section taken along an optical axis of the laser light, such that it is larger from the side of the laser source than from the side of the air channel, and
the aperture in the second intermediate wall is conical in a cross-section taken along the optical axis of the laser light, such that it is larger from the side of the air channel than from the side of the laser source.