Optoacoustic Fluid Sensing Apparatus

An apparatus for measuring a measurement target in a fluid flow (contaminant in an aqueous flow), the apparatus comprising:

• an ellipsoidal measurement chamber (3) having a first focal point (37) and a second focal point (38);
• a duct (6, 7, 8) configured to guide a fluid flow through the measurement chamber (3) along a first axis (X) through the first focal point (37);
• light source means (21, 22) for generating an excitation light beam (19) of modulated intensity;
• means (12, 15, 16) configured to pass the excitation light beam (19) through the measurement chamber (3) along a second axis (Y), which is different from the first axis (X), such that the excitation light beam crosses the fluid flow at the first focal point (37) and that the crossing of the fluid flow and the excitation light beam defines an excitation volume (4) within the fluid flow is excited by the excitation light beam to generate acoustic waves;
• and
• detecting means (5) arranged at the second focal point (38) and configured to detect said acoustic waves, wherein the detecting means has no direct contact with the fluid flow, and wherein the ellipsoidal measurement chamber has inner walls that are configured to focus the acoustic waves generated by the excitation light beam (19) within the excitation volume (4) onto the detecting means (5).

A method of measuring gaseous and particulate species (87) using a photoacoustic apparatus as defined in claim 1 to measure in the exhaust of different combustion systems including cars, vessels, aircraft, stationary engines, comprising the steps of

• detecting and monitoring gaseous or particulate pollutants from combustion, including engines, boilers, burners and other combustion setups, are detected and monitored,
• wherein said sensor (44, 45) provides real-time evaluation of pollutants' concentration at said exhaust of said combustion systems, stationary engines and combustion devices,
• wherein said sensor in engine exhaust serves as on-board detection (OBD) sensor or on-board monitoring (OBM) sensor,
• wherein said sensor is configured as a particle number (PN) sensor;
• or
• wherein air quality is detected and measured for atmospheric pollution concentrations and/or wherein light at different wavelengths is used and/or wherein the optoacoustic sensor is used as a multicomponent sensor, wherein the CO2 is measured to monitor the actual emissions of CO2.