There is described a method for detecting a given gas species present in a gaseous sample. The method generally has splitting a primary optical pulse into first and second optical pulses, the primary optical pulse having a duration and carrying optical power within an excitation spectrum encompassing at least one absorption spectral band of the given gas species, the first optical pulse being propagated across an optical gas filter unit containing an amount of the given gas species and attenuating the first optical pulse at the at least one absorption band, one of i) the primary optical pulse and ii) the first and second optical pulses being propagated across the gaseous sample, and temporally delaying the first and second optical pulses from one another; measuring signal values of the delayed optical pulses; and detecting the presence of the given gas species in the gaseous sample based on the signal values.

A gas supply and discharge adapter has an opening through which a gas flows into and out of a gas sensor, an inflow port through which the gas flows into the opening, and an outflow port through which the gas flows out of the opening. The inflow port and the outflow port are positioned independently of each other. When the inflow port and the opening are viewed in plan through the gas supply and discharge adapter, the inflow port partially overlaps the opening.

In order to analyze a solution component and a scatterer component in a liquid sample more quickly, there is provided an optical analysis device including a light source unit configured to irradiate a liquid sample with light; a first light receiving unit configured to receive transmitted light emitted from the light source unit and transmitted through the liquid sample; a second light receiving unit configured to receive scattered light emitted from the light source unit and scattered by a scatterer in the liquid sample; an ultrasonic irradiation unit configured to irradiate the liquid sample with an ultrasonic wave; a reflection plate configured to reflect the ultrasonic wave that is emitted from the ultrasonic irradiation unit and propagated through the liquid sample; and a control unit configured to control the light source unit, the first light receiving unit, the second light receiving unit, and the ultrasonic irradiation unit.

In order to analyze a solution component and a scatterer component in a liquid sample more quickly, there is provided an optical analysis device including a light source unit configured to irradiate a liquid sample with light; a first light receiving unit configured to receive transmitted light emitted from the light source unit and transmitted through the liquid sample; a second light receiving unit configured to receive scattered light emitted from the light source unit and scattered by a scatterer in the liquid sample; an ultrasonic irradiation unit configured to irradiate the liquid sample with an ultrasonic wave; a reflection plate configured to reflect the ultrasonic wave that is emitted from the ultrasonic irradiation unit and propagated through the liquid sample; and a control unit configured to control the light source unit, the first light receiving unit, the second light receiving unit, and the ultrasonic irradiation unit.

The present invention relates to a gas sensor (100) comprising a measurement chamber (102) for measuring presence of a first gas, the first gas being nitrous oxide (N.sub.2O) and an optical source (103) for emitting radiation in the measurement chamber (102). The sensor also comprises a radiation detector (104) sensitive to radiation emitted by the optical source (103), the radiation being detected by the radiation detector (104) following passage through the measurement chamber (102). A diffusion layer (131) is configured to allow diffusion of ambient gas into and out from the measurement chamber (102), and the diffusion layer (131) comprises means (133) for preventing diffusion of carbon dioxide (CO.sub.2) in the ambient gas into the measurement chamber (102). The invention also relates a nitrous oxide detector comprising such a gas sensor, and a method for determining presence of nitrous oxide in the ambience.