Abstract: A device for measuring the particle content of air comprises 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, and a light detector located adjacent to the target area for detecting bursts of light generated as the particles entrained with the air flow scatter the laser light in the target area. The device comprises a light trap between the laser source and the target area for reducing stray light propagating to the target area. The light trap comprises at least two intermediate walls which are substantially transverse in relation to the propagation direction of the 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. The intermediate walls are part of a same piece manufactured as one continuous block.

Abstract: A stove guard having a data processing unit and a heat sensor arrangement for receiving heat radiation from objects located in a given field of view and for delivering the detector signals indicative of the received heat radiation to the data processing unit. The heat sensor arrangement is arranged to generate detector signals differently corresponding to the heat radiation received from a central area of the field of view than to the heat radiation received from a circumferential area of the field of view.

Abstract: A stove guard comprises a data processing unit (101) and a temperature sensor arrangement (102) for receiving thermal radiation from objects in a specific field of view and for supplying detector signals representative of the received thermal radiation to the data processing unit (101). The temperature sensor arrangement (102) includes at least three detector elements (201, 202, 203), their sensitivity bands located at different positions along an optical radiation wavelength axis. The sensitivity band of one of said detector elements is limited to a wavelength range of less than 1.2 micrometers.

Abstract: A stove guard arrangement includes sensors for detecting events on a stove and for providing detection data, and a programmable processing component for analysing the detection data and for providing exceptional situation data in response to the detection data indicating an exceptional situation defined in the programming of the processing component. The stove guard arrangement comprises a receiver connected to the processing component and arranged to receive radio-frequency interference and to provide corresponding reception data. The processing component is arranged to recognize regular changes in said reception data and derive, on the basis of the recognized regular changes, a conclusion that the stove is an induction stove.

Abstract: A stove guard comprises a data processing unit (101) and a temperature sensor arrangement (102) for receiving thermal radiation from objects in a specific field of view and for supplying detector signals representative of the received thermal radiation to the data processing unit (101). The temperature sensor arrangement (102) includes at least three detector elements (201, 202, 203), their sensitivity bands located at different positions along an optical radiation wavelength axis. The sensitivity band of one of said detector elements is limited to a wavelength range of less than 1.2 micrometers.

Abstract: A stove guard having a data processing unit and a heat sensor arrangement for receiving heat radiation from objects located in a given field of view and for delivering the detector signals indicative of the received heat radiation to the data processing unit. The heat sensor arrangement is arranged to generate detector signals differently corresponding to the heat radiation received from a central area of the field of view than to the heat radiation received from a circumferential area of the field of view.