Better solutions for air quality awareness

Pupil Imaging Gas Correlation technology

Thanks to advances in modern uncooled detector technology, remote communication, GPS global positioning, solar cell panels, cheap miniature processors, small inexpensive pointing systems, and a novel spectrometric technique, a simple solution is now made possible by combining these elements into a next generation compact trace gas sensor capable of remote connection and autonomous operation.

The size and complexity reduction is made possible by implementing a new form of GFCR, named the Pupil Imaging Gas Correlation approach (PIGC™, pronounced “Pigzy”) [Gordley et al., 2013]. As opposed to the limb viewing observation HALOE, PIGC was conceived to detect the presence of specific trace gases near the Earth’s surface from ground based platforms [1]. This technology is based on a simple beam splitter gas correlation technique in pupil imaging optical configuration.

Being a GFCR technology, PIGC detection takes advantage of the absorbing nature of certain molecules, to visualize them in their native environments. The sensor detector and optical systems are specifically tuned to narrow spectral ranges, in the order of hundreds of nanometers, and are therefore offer high selectivity. Only gases absorbent in the infrared region that is delimited by a narrow band pass filter can be detected. This advantage limits perturbation by other molecular species and limits false alarms.

The main principle of the PIGC approach is to use a sample of the gas of interest as a spectral filter inside the sensor. To measure the concentration of a gas in the atmosphere, the gas filter radiometer correlates the pattern of the spectral lines of the observed radiation with the pattern of the spectral lines in the reference gas cell. As a consequence, this type of sensor combines the advantages of the high-resolution spectral selectivity of a spectrometer (from the gas of interest) with the energy grasp of a low-resolution radiometer.


[1] In the planetary boundary layer (PBL), the lowest part of the atmosphere where all weather phenomena occurs.