A photoacoustic gas sensor is provided. The photoacoustic gas sensor includes a hermetically sealed housing filled with a reference gas. Further, the photoacoustic gas sensor includes a microphone system arranged inside the housing. The microphone system is configured to generate a first microphone signal comprising a first signal component related to a photoacoustic excitation of the reference gas and a second microphone signal comprising a second signal component related to the photoacoustic excitation. The photoacoustic gas sensor additionally includes a circuit configured to generate an output signal based on the first microphone signal and the second microphone signal by destructively superimposing a third signal component of the first microphone signal related to mechanical vibrations of the photoacoustic gas sensor and a fourth signal component of the second microphone signal related to the mechanical vibrations.

A non-dispersive photoacoustic gas detector includes an infrared light source, a first closed chamber, a first acoustic sensor in fluid communication with the first closed chamber, a second closed chamber, and a second acoustic sensor in fluid communication with the second closed chamber. The first closed chamber comprises a plurality of windows that are substantially transparent to infrared light from the infrared light source. The second closed chamber comprises at least one window that is substantially transparent to infrared light from the infrared light source, and the first closed chamber is arranged in series with the second closed chamber between the infrared light source and the second closed chamber.

A non-dispersive photoacoustic gas detector includes an infrared light source, a first closed chamber, a first acoustic sensor in fluid communication with the first closed chamber, a second closed chamber, and a second acoustic sensor in fluid communication with the second closed chamber. The first closed chamber comprises a plurality of windows that are substantially transparent to infrared light from the infrared light source. The second closed chamber comprises at least one window that is substantially transparent to infrared light from the infrared light source, and the first closed chamber is arranged in series with the second closed chamber between the infrared light source and the second closed chamber.

Heating arrangement for a materials testing device, the materials testing device comprising at least one surface measurement probe adapted to be brought into contact with a surface of a sample, the heating arrangement comprising a probe heater comprising: an infrared emitting element adapted to emit infrared radiation; a reflector having a reflective surface arranged to direct said infrared radiation towards a distal end of said surface measurement probe. According to the invention, the reflector comprises a first focal point and a second focal point, the infrared emitting element being situated substantially at said first focal point.

Heating arrangement for a materials testing device, the materials testing device comprising at least one surface measurement probe adapted to be brought into contact with a surface of a sample, the heating arrangement comprising a probe heater comprising: an infrared emitting element adapted to emit infrared radiation; a reflector having a reflective surface arranged to direct said infrared radiation towards a distal end of said surface measurement probe. According to the invention, the reflector comprises a first focal point and a second focal point, the infrared emitting element being situated substantially at said first focal point.

Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

A non-dispersive photoacoustic gas detector comprises an infrared light source, a closed chamber, a gas sample disposed within the closed chamber, and an acoustic sensor in fluid communication with the dosed chamber. The dosed chamber comprises at least one window that is substantially transparent to infrared light from the infrared light source, and the gas sample comprises a gas or a mixture of at least two gases.

A non-dispersive photoacoustic gas detector comprises an infrared light source, a closed chamber, a gas sample disposed within the closed chamber, and an acoustic sensor in fluid communication with the dosed chamber. The dosed chamber comprises at least one window that is substantially transparent to infrared light from the infrared light source, and the gas sample comprises a gas or a mixture of at least two gases.