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Characteristics of the sensor

This new original and versatile aerosol counting instrument doesn’t use any lens, only a laser beam and two scattering angles, respectively at 12° and 60 ° allowing to determine the concentration of aerosols (numbers of aerosols per cm3) for 19 size classes between 0.2 and 30 micrometers. The combination of these two angles allows also to identify the typology of the aerosols according to 5 main families of particles (Carbons, Droplets, Ice, Salt and Minerals). The instrument can be used for several purposes:  to document the physical properties of aerosols in the lower and middle atmosphere during specific events like pollution peaks, transported sands, volcanic ashes, and/or for long-term monitoring purposes.


2 angles of measurement. The first is approximately at 12° and is almost insensitive to the nature of particles whereas the second at 60° is strongly sensitive to the refractive index of the aerosols. By combining these two measurement-angles it’s possible to retrieve accurately the size distribution and assess the main nature of the particles crossing the laser.

Principle of Measurement

  • Light and compact: 300g

  • Pump: 2l/min

  • No lense: no risk of misalignment

  • Measures every 10 seconds

  • Automatic check every ten minutes

  • Real time stray light correction applied


The LOAC is available in two versions:

  • The surface version is called LOAC Recorder

  • The LOAC Telemetry, the airborne version for Tropospheric and stratospheric measurements.

LOAC Telemetry

Measurement under balloon up to 40km.
LOAC telemetry

LOAC Version interfaced to a M10 Radiosonde allowing data transmission in real time to the ground receiver.

This solution is packed in a light gondola, less than 1 kilo. 

Modular Instrument that can be used under several type of balloons for atmospheric and stratospheric soundings


Low electric consumption: 3W

The LOAC works with the Eoscan software, which allows it to be compatible with all Meteomodem systems.

LOAC Recorder

Ground particle measurement.

Last version of the LOAC developed to focus on surface continuous observation.


This version is made up of a LOAC sensor, a GPS and an embedded acquisition system. The data collected are stored on a USB flash or available in real-time by connecting the LOAC-R to an internet network. It is powered by the mains or by its internal rechargeable battery.

The LOAC-R  can be used  for several purposes such as urban  long term pollution monitoring, installed on roof tops, in a tunnel, school yards, streets.

LOAC Recorder

More than 100 LOACs manufactured and sold worldwide.

Permanent network measurement in three main sites in France:

  • OAG in Paris: for analysis of the variations in concentration of the nature of urban aerosols and mainly during strong pollution events.

  • Ground based measurement at SIRTA dedicated to the detection of Fog events.

  • CNRS Orleans for the monitoring and identification of troposphere and stratosphere aerosols.

  • Meteorological services: Particles/Aerosol Research, Physical documentation of aerosol properties, study of specific events such as sand plume, volcanic eruptions, strong pollution events…

  • Research: laboratories, Specialized atmospheric Research institutes, Universities for several type of Study from the detection of fog to monitoring of urban pollution

  • Air quality control authorities such like Cities/ Regions…

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