An apparatus for optical in-situ gas analysis includes: a housing; a measuring lance a first end connected to the housing and a second end projecting into the gas to be measured; a light transmitter that is arranged in the housing and whose light is conducted into the measuring lance and is reflected by a reflector arranged at the second end onto a light receiver, and the optical path defines an optical measurement path within the measuring lance; and, an evaluation device for evaluating received light signals of the light receiver. In order to be able to reduce the consumption of test gas, the measuring lance has an outer tube, with the outer tube having openings for the gas to be measured. The openings can be closed by at least one seal for the test phase, with the seal searingly closing the openings by the enlargement of its volume.

A wood stove monitoring and control device can include a mounting flange mountable to a chimney exhaust pipe of a wood stove. The device can include a ring removably mountable on top of the mounting flange, where the flange is suitably positioned vertically along the exhaust pipe so that the ring is positioned at least partially above an end of the exhaust pipe. The device includes an optical beam source disposed on the ring, and which generates and outputs an optical beam. The device includes an optical sensor positioned on the ring opposite the optical beam source to detect the optical beam output by the optical beam source as the optical beam passes through smoke exhausted by the wood stove through the exhaust pipe. The device can include a temperature probe disposed on the ring to measure a temperature of heat exhausted by the wood stove through the exhaust pipe.

There is described a method for remotely monitoring an exhaust plume emitted by an exhaust stack, the method comprising: determining a velocity of a flow of the exhaust plume at an output of the exhaust stack, the exhaust plume comprising one molecule; propagating a first light within the exhaust plume, the first light being propagated in close proximity to the output of the exhaust stack; detecting a second light emitted by the exhaust plume and measuring an energy of the second light, the second light resulting from an interaction of the first light with the exhaust plume; and determining a mass emission rate of the at least one molecule using the measured energy of the detected second light, the velocity, and a surface area of the exhaust plume at the output of the exhaust stack, the surface area being orthogonal to a direction of the flow of the exhaust plume.

A device for measuring scattered light from a measurement volume with compensation for background signals, includes a light sensor having separately evaluable light-sensitive elements, a single imaging optical system, wherein the light-sensitive elements are arranged in the image plane and the measurement volume is arranged in the corresponding object plane of the optical system, a light transmitter with a collimated light beam, this light-sensitive element detects scattered light from the measurement volume and background light from the overlapping visual ranges behind the subject plane, and the other light-sensitive element detects no or significantly less scattered light from the measurement volume and background light from the overlapping visual areas behind the object plane, and a diaphragm that restricts the visual ranges of the light-sensitive elements behind the object plane.

The present invention relates to an analysis apparatus for analyzing a gas sample comprising a concentration measurement path receiving the gas sample; a light transmitter for transmitting light signals into the concentration measurement path; a detector for detecting light signals exiting the concentration measurement path; an evaluation unit which is adapted to determine the concentration of at least one substance present in the gas sample on the basis of the intensity of the detected light signals and on the basis of the length of the concentration measurement path; and a measurement device which is configured to determine the length of the time of flight path of the transmitted light signals optically using the light transmitter, with the evaluation unit being adapted to determine the length of the concentration measurement path on the basis of the determined length of the time of flight path.

An optical sensor is arranged in an indentation of a dust line, the indentation being equipped with at least one gas inlet nozzle for removing the dust from the optical sensor. Dust is transported through the dust line. An optical property of the dust is measured using at least one optical sensor arranged in an indentation of the dust line, and the dust is then removed from the optical sensor by blowing in air using the at least one gas inlet nozzle arranged in the indentation.