Calibration of Optical Open-Path Instruments
The instrumentation and expertise available within the Analytical Science Team (AST) enables a wide range of calibration requirements to be covered for open-path analytical techniques, including FTIR (Fourier Transform Infrared), DOAS (Differential Optical Absorption Spectroscopy), DIAL (Differential Absorption Lidar), etc. Calibration of such analysers under realistic field conditions is often difficult due to the open path measurement configuration, however, specialised facilities have been developed at NPL that make this possible.
For example, the cell shown above is specifically designed without windows so that calibration gas can be pumped in at either end whilst vapour is extracted from the centre. Consequently, atmosphere is drawn into the cell creating realistic sample conditions.
The cell shown on the right has been built on a portable platform so that it may introduce calibration gases by moving in and out of line with the sample beam. The on-board pumping system allows a wide range of sample pressures to be attained and the Teflon lining enables the use of harsh industrial gases typical to many regulatory monitoring applications.
If you would like further information of the calibration service we can provide please contact Marc Coleman or Rod Robinson