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The Advantage of Changeable Spectral Filters in your OGI Camera


3 mins


Ilan Waldman

published published

January 09, 2022


OGI Knowledge BaseOptical Gas Imaging (OGI)

The Advantage of Changeable Spectral Filters in your Optical Gas Imaging (OGI) Camera

There are two kinds of OGI cameras: cooled and uncooled. Cooled cameras, like the EyeCGas 2.0, allow us to detect small to large leaks (methane and over 400 VOCs) from various distances, up to 10 kilometers away and more.

Whereas uncooled OGI technology, such as the EyeCGas Mini, is slightly limited in its capabilities, detecting medium to larger leaks (methane) closer to the source.

Inside the EyeCGas 2.0 OGI camera, we use a spectral filter to enhance compound detection in a specific wavelength. EyeCGas 2.0 is the only OGI camera that enables you to change the spectral filters; this ensures improved detection capability for VOCs and CO2 within the same camera.

By not having the option to change a spectral filter, you are limited to the standard filter (see chart below), which is good enough in perfect weather conditions, such as no wind or humidity.

Standard Spectral Filter Response OGI

In humid conditions or at longer distances, having the option to change to a heavy alkanes spectral filter vastly improves the camera’s VOC detection capabilities.

The chart below shows the different filters and absorption characteristics of some of the compounds they detect. Methane is detected better with the standard filter; however, VOCs are detected better with the heavy Alkanes filter.

MWIR EyeCGas OGI Camera Bandpass Filters

As far as CO2, in the chart below, you can see the detector of the EyeCGas 2.0 (VOC) camera is open to up to 4.3 microns; therefore, by placing the CO2 filter, we can also detect CO2. The chart below summarizes the three different filters offered with the EyeCGas 2.0.

Hot Filter Comparison - VOC EyeCGas 2.0 OGI Camera

To summarize, for optimal performance with your OGI camera, you should always have the option to change the filters (it takes about one minute).

Use the standard filter (center ~3.3 µm) for methane and VOCs in good weather conditions. For improved VOCs (Hexane, Octane, Butane, Pentane, Heptane, etc.) detection in humid conditions and longer-range, switch to a heavy alkanes filter (center ~3.4 µm), and for CO2, change to the CO2 filter.

Changing the Spectral Filter in EyeCGas OGI Changing the Spectral Filter in EyeCGas OGI 2