Range vs. Environment Limitations

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Range vs. Environment Limitations
IR Talk
The Snell Group

Just because your camera has a very high or very low temperature range capabilities does not mean your camera will operate in those conditions. We must distinguish between the camera’s temperature range capabilities and its operating environment temperature capabilities. The cameras’ range is defined as: “the preset range of temperatures that can be viewed and/or measured”.  Some cameras have a single preset range of temperatures and others have two or more presets that must be appropriately selected by the operator.

Looking at a typical multi-range camera we find the following preset ranges; range #1= -40C. - 120C (-40F-248F), range #2= 0C - 500C (32F-932F) and range #3= 200C-2000C (392F-3632F).  Because of this large swing from very cold to very hot temperature capabilities it is easy to assume that we could be working in some extreme ambient conditions as well. We often overlook the operating environmental limitations found on the specification page of the owner’s manual.

If we look for this operational limitation for the same camera we find -15C-50C (5F-122F). That’s quite a difference from the camera’s temperature range values. Most infrared cameras environmental limitations are comparable regardless of manufacture or model. It is often necessary to work outside these recommended parameters so we must understand that during these times our temperature data could be less than accurate. At some point, internal temperatures will reach the point where they cannot be stabilized and functionality of the camera will also suffer.

When moving from hot to cold areas, or vice versa, condensation on the camera’s lens can also present a problem. Condensation on the lens can cause your camera to be less than accurate. As such, you should keep an eye out for condensation when moving to and from environments with drastically different temperatures. A thin film plastic bag over your camera can reduce or eliminate the formation of condensation on your camera. However, moisture in the form of condensation on the thin film plastic may change the percentage transmission you carefully measured and compensated for, increasing the error in any measured temperatures. Another issue that pops up when moving from environments with different temperatures is the Non-Uniform Correction (NUC). Expect your camera to automatically NUC, if so equipped, and freeze frame more frequently until it stabilizes in the new environment.

We can often protect the camera by keeping it in a suitable stable environment until we need it, then use it quickly and return it to stabilize. This could be as simple as placing it inside your jacket when not in use.  Your camera’s thermal range capability and operating range capability should both be contained in your operator’s manual. Take a few minutes to make sure you know what these ranges are.

With a little understanding and forethought, we can extend the capabilities of our imager in many extreme conditions. And remember to Think Thermally®!

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