How it works

Nikira Labs’ Open-Path Optical Extinction Analyser (OEA) is an advanced and precise instrument designed to offer real-time assessments of total aerosol optical extinction and visibility, with no calibration, sampling effects, or assumptions. Using open-path cavity ringdown spectroscopy, the OEA measures the total optical extinction from first principles. This measures the optical loss due to the cavity mirrors and ambient air with aerosols.

How does the OEA work?

1. Fans pull ambient air through a duct at a speed of ~1 m/s.
2. Using open-path cavity ringdown spectroscopy, direct measurements of the optical extinction coefficient (beta) within the sample are taken.
3. The duct is intermittently closed, followed by purging the cell with filtered air to a background measurement.
4. The difference between the readings obtained with the dust open and closed provides a direct, calibration-free measurement of the aerosol optical extinction

The clean air purge is used to prevent deposition on the mirrors. Through periodically closing the cavity and purging it with filtered air, the OEA is able to measure the background optical loss resulting fom the cavity mirrors and ambient air in the absence of aerosols. The subtraction of closed cavity optical loss from open cavity optical loss facilitates the precise determination of absolute optical extinction due to ambient aerosols through first-principles with no calibration.

What does the OEA measure?

• The OEA measures total optical extinction due to aerosols at a specific wavelength without sample handling losses or calibration.
• Total optical extinction is also called visibility, so the OEA measures visibility at a specific wavelength.
• Can be used to estimate other critical aerosol parameters (e.g. PM₂.₅, total aerosol loading, etc..) through a series of assumptions regarding aerosol size distribution and type.

Servicing

Contact us for servicing information.