This is something I’ve thought about for quite a while. We had one as an option in our F1 setup back in 93. It was useful for profiling the circuit, especially as the suns heating changed.
This particular device is used on snowplows and other transportation equipment. One of the concerns we had way back when was contamination of the optical assembly, and yes, we did pick up oil, and dirt. It appears this outfit solved the problem with the inverted cone, although in slush conditions, it would still seem to be an issue where it could become plugged up. In addition, unless their optical design is right on the money, the inverted cone is going to serve as an inherant radiator, and as such, really mess with the accuracy of the device. Especially so, in cases of changing environmental conditions. Infrared radiometers are incredibly sensitive to dTa/dt where Ta is ambient temperature, and t is time.
Another possible solution to mitigate contamination is a high volume air jet. Its easy to do in an industrial environment, but getting clean and dry air in an automotive environment is problematic. We did look at this, but the weight penalty of a filter/pump assembly, and the lack of clean air via ducting alone made such an approach less than tenable.
If I were still in the business, it would be a cool project to reverse engineer this device to see what they did, as well as to check the accuracy of this device.
As another cool project, adding a Lassen GPS, and APRS capability to moblog would be super cool.