In our recent post about the new Bosch thermal imaging camera and their new “thermo detector”, Jimmie asked a great question in the comments section:
I’m still a little fuzzy (a lot fuzzy, actually) on the distinction between a “thermo detector”, a visual IR thermometer and a full-fledged thermal imaging camera.
In day-to-day use, how do they differ?
This can be a very simple, or very difficult question to answer. I’m going to simplify things.
A thermal imaging camera, such as the Flir E4 (with or without firmware modification), Flir C2 pocketable thermal imager, and new Bosch model, are designed to capture higher quality thermal images, and record temperature measurements for each sensor pixel. For example, the 80x60px Flir E4 produces a thermal image with 4,800 data points.
Thermal imaging cameras typically have greater functionality and features built in, such as multiple color palettes, measurement modes, visual image blending, overlays, or enhancements, and there are more and more models that also offer video recording.
An imaging thermometer, such as the Flir TG165 we reviewed, Fluke VT02 and VT04, or Dewalt 12V model, provide thermal visuals that are more intended for guidance purposes. These devices are sometimes described as visual thermometers as well.
Imaging, or visual thermometers, are typically, smaller, less expensive, less featured, and much simpler to use. They’re mainly used for identifying trouble areas where a single temperature measurement is desired.
Thermal imaging cameras have far more powerful imaging capabilities that can be useful for analyzing a situation and producing a report. Imaging thermometers are simpler means of identifying a trouble spot and obtaining a temperature measurement for the target area.
Imaging thermometers are a new class of tool that’s meant to bridge the gap between infrared thermometers and full-fledged thermal imagers. Although there is some overlap in how both types types of thermal imaging devices can be used, imaging and visual thermometers lack the resolving, measurement, imaging, and reporting power of true thermal imaging cameras.
Rather than a step down from thermal imaging cameras, it’s better to consider imaging thermometers as a step up from simple IR thermometers. Compared to IR thermometers, imaging thermometers provide context to what and where you’re trying to measure.
Speed (frames per second and how long an event must be to register) is one of the major differences as well. I can pan over a large area looking for a transient arc with a camera and find it more often than not. With a thermometer, it’s sheer dumb luck if it registers at all, even if I can see and smell it myself and I know it is within the device’s viewfinder.
Not necessarily. Flir’s TG165 imaging thermometer has a refresh rate of 9Hz, which is the same as many models of thermal imaging cameras.
Interesting! I always thought the difference was simply in the underlying function of the device. A Thermal Imager/Imaging Thermometer is used as an active representation of a series of data points, where a Thermal Imaging Camera is a device that can record and/or examine an actual image with Thermal Data overlay.
The difference, though confusing, I always thought was the difference in how the device made the image. A Camera takes the picture, and the sensor readings, and overlays them, where a Thermal Imager or Imaging Thermometer takes the sensor reading data points and lines them up into an image.
I never thought of it in terms of data capabilities before. Thanks!
Technically, imaging thermometers, visual thermometers, and thermal imaging cameras are all thermal imagers.
The difference is similar to that between a webcam and a dSLR camera.
A thermal image isn’t formed by taking a picture, although overlay, blending, and enhancement capabilities can cause some confusion. A thermal image is created by measuring thermal intensity and then applying the relative values to a color scale. This gives you the grayscale image. What you’re seeing isn’t a visual image – it’s formed purely from the infrared wavelengths. Imagery taken from a visual camera sensor helps to greatly improve the context and understanding of a thermal image.
You can create a thermal image in a pitch-black room, as visual light wavelengths do not at all contribute to the pure thermal image.
But yes, thermal imaging cameras often capture image data for EVERY data point, whereas an imaging thermometer only uses infrared intensity data to create an image. The temperature data is usually only captured for a target area towards the middle of the sensor array or maybe from a separate sensor.
It’s even more confusing because visual/imaging thermometers only recently offered lousy resolution, such as 15 x 15px, but now you have instruments like the Flir TG165 which is built with a thermal imaging core. The same Lepton core is used in Flir’s recent and upcoming simple and compact thermal imaging cameras.
As I tried to hint, the differences get really muddy, which is why I wanted to make generalizations.
That’s why I never thought of it that way before. I’m out of the loop on these particular tools. The last time I checked, the difference was that one was a Camera, and the other was an Image made out of Data Points. Things have obviously changed since then.
Even in a dark room, Light is present. If the sensor is wider than the 4mm diameter of the Human Eye, it can pick up more light waves, and therefore a wider part of the spectrum, than we can physically see. Into that range of the Infrared included. So obviously they’ve found a new way of imaging rather than just a wider-range lens like I learned about originally.
I’m still glad to get an updated lesson in this! Though… Now I want one to play with, and they’re too expensive to do that… but, hey, it’s still cool to know this stuff!
I find it easy to understand because electron microscopes work in a similar manner.
As with thermal images, electron micrographs aren’t photographs or images, they’re composite images made up of many intensity readings. Greater intensity = brighter/whiter in the grayscale. Lower intensity = darker/blacker in the grayscale.
I didn’t say a dark room – I said pitch-black room. If there’s absolutely no source of visible light in a room, such as a windowless closet or bathroom that is perfectly enclosed, then there’s not going to be any visible light. Infrared is different, because everything emits IR radiation that’s proportional to their thermal energy and temperatures. You won’t find many things in a typical pitch-black room that emits light that’s visible to the human eye.
Sensor width does not determine which part of the light spectrum that could be detected. If you enlarged the human eye such that its pupil was significantly larger, the person might be able to see better in the dark, but they wouldn’t see a wider part of the spectrum.
For example, if you take a camera lens and open the aperture, you’re going to collect more light, but the sensor won’t be able to see wavelengths invisible when the aperture is closed down quite a bit.
A wider-aperture lens could NOT pick up the infrared spectrum. Thermal imaging cameras typically have wide dome-shaped lenses, but this is more to produce a wider field of view. That’s not what makes the cameras more sensitive to infrared radiation.
We had an energy audit done a few years back…cold winter day. Amazing watching the Flir camera show how poorly my home was insulated. I’ve wanted one ever since.
would the FLIR TG 165 be a good instrument to find hot water radiant leaks in slabs
I have the tg 165 for electrical trouble shooting and inspections on multiple solar fields I take care of. It’s a great tool and capturing images to view later is awesome. The flir is my personal tool and my company also has a high dollar fluke unit and that stays at shop most of the time unless I’m doing a more in depth report. Thanks for the read.
For got to mention if you do any type of trouble shooting or inspection work the flir has a great price for you to add it to your own tools. Nothing worse than trying to get a tool from shop and it’s gone or broken. I don’t lend my flir out to anyone because it’s mine. ?
mines dont see mold but does show water leak through the roof and onto the ceiling. and the human aura. animals and so on. but the house washed out when i use it to find cold or hot spots. not sure why has to be lower then level to the home. i have the tg165. and the flir mate far more clear then the tg165 but don’t have a photo capture, but want one 2989 dollars have video tape feature