The invention relates to an apparatus (11) for analysing an exhaust gas of a vehicle, comprising a sample chamber (29) for receiving the exhaust gas, a heating device (24) for heating the exhaust gas provided to the sample chamber (29), and an infrared analysis device (23) having an infrared transmitter and an infrared receiver. The infrared transmitter is operable to transmit an infrared beam into the exhaust gas in the sample chamber (29), and the infrared receiver is operable to receive scattered infrared light from the exhaust gas in the sample chamber (29). The infrared analysis device (23) is operable to receive a signal from the infrared receiver and to compare it with a threshold level. A pass indication is issued if the exhaust gas is below the threshold level and a fail indication is issued if the exhaust gas is above the threshold level. The threshold level may correspond to a change in signal level equivalent to a predetermined density of particulates in the exhaust gas. The infrared receiver may be configured to generate the signal based on infrared light scattered from particles having a particle size preferably in the range 0.3 m to 10 m. Processing circuitry is preferably configured to operate the apparatus in a warm-up mode during a first period, during which the heater device (24) is activated. A fan (22), upstream of the sample chamber (29) and for delivering exhaust gas thereto, may be operated at one of a plurality of selectable fan speeds, the fan (22) being successively switched to higher ones of the selectable fan speeds. A method of analysing an exhaust gas is also disclosed.

An optical density measuring apparatus and an optical waveguide capable of increasing the degree of design freedom are provided. The optical density measuring apparatus is for measuring density of a gas or a liquid to be measured and includes a light source capable of irradiating light into a core layer, a detector capable of receiving light propagated through the core layer, and an optical waveguide. The optical waveguide includes a substrate and the core layer, which includes a diffraction grating unit and a light propagation unit capable of propagating light in an extending direction of the light propagation unit. The diffraction grating unit and a portion of the core layer are separated in the thickness direction of the optical waveguide.

An assembly and a method for measuring a gas concentration by means of absorption spectroscopy, in particular for capnometric measurement of the proportion of CO.sub.2 in breathing air in which IR light from a thermal light source is guided through a measuring cell with a gas mixture to be analyzed, and the concentration of the gas to be measured that is contained in the gas mixture is determined by measuring an attenuation of the light introduced into the measuring cell caused by absorption by the gas to be measured. The thermal light source is designed as an encapsulated micro-incandescent lamp with a light-generating coil.

A gas sensor includes: a gas chamber with a supply opening and a discharge opening, so as to permit gas to flow through the gas chamber; a magnetic field device for providing a magnetic field in the gas chamber; a light source for generating a light beam that extends through the gas chamber; and a detector for detecting the light beam, which detector is arranged opposite the light source.

The invention relates to a method and to a device for monitoring the quality of gaseous media which can be dispensed by a filling station, in particular hydrogen, by means of an infrared measuring system (42), which is connected into the dispensing path of live respective gaseous medium running fom the filling station to a consumer, and which measures the transmission of infared radiation at different wavelengths and different pressures and calculates therefrom the concentration of contaminants, which influence the quality. At least when predeterminable quality parameters are exceeded, this is indicated.

Described herein is a spectroscopic system and method for measuring and monitoring the chemical composition and/or impurity content of a sample or sample stream using absorption light spectroscopy. Specifically, in certain embodiments, this invention relates to the use of sample pressure variation to alter the magnitude of the absorption spectrum (e.g., wavelength-dependent signal) received for the sample, thereby obviating the need for a reference or zero sample. Rather than use a reference or zero sample, embodiments described herein obtain a spectrum/signal from a sample-containing cell at both a first pressure and a second (different) pressure.

Described herein is a spectroscopic system and method for measuring and monitoring the chemical composition and/or impurity content of a sample or sample stream using absorption light spectroscopy. Specifically, in certain embodiments, this invention relates to the use of sample pressure variation to alter the magnitude of the absorption spectrum (e.g., wavelength-dependent signal) received for the sample, thereby obviating the need for a reference or zero sample. Rather than use a reference or zero sample, embodiments described herein obtain a spectrum/signal from a sample-containing cell at both a first pressure and a second (different) pressure.

A system and method for high-throughput, high-resolution gas sorption screening are provided. An example system includes a sample chamber with a hermetic seal and a heat exchanger system. The heat exchanger system includes a heat exchanger disposed in the sample chamber, a coolant circulator fluidically coupled to the heat exchanger, and a sample plate comprising sample wells in contact with the cooling fluid from the coolant circulator. The system also includes a gas delivery system. The gas delivery system includes a gas source and a flow regulator. A temperature measurement system is configured to sense the temperature of the sample wells.