Infrared Light: Research

Seeing Underground: Detecting Land Mines

The United Nations estimates that there are currently 100 million landmines around the world, in nearly 80 countries. Many of these countries do not have accurate records of where the mines are.  Because landmines are designed to explode under the weight of unsuspecting passersby and so are not well marked, those still in existence present a great threat to civilians in the area.

Most land mine detectors consist of a variety of sensors that record the conditions of the area and look for abnormalities. Thermal imaging is often used because there are detectable differences in how explosive devices and the surrounding soil absorb and release heat. This causes a pattern of temperature changes over the surface of a mine that is different than over regular soil, which can give scouts a heads up to take a closer look at the area.

An image taken by an infrared camera which shows the thermal signatures of two simulated landmines buried in soil (shown by yellow dots).

As you might imagine, the type of soil, moisture content, and amount of sunlight can all impact infrared readings, so scientists are doing experiments to model the effect of these variables on the accuracy of the detectors. The image below is from the test of a detection method designed by engineers at Ryerson University and the American University of Beirut in Lebanon, which showed that an infrared beam could easily identify detonators buried under two centimeters of soil or less.

Other sensors that might be used in conjunction with infrared mapping include metal detectors (although most recent mines were made with non-metallic weapon), ground penetrating radar systems, and devices that look for changes in the magnetic field of the area. Scientists are continually working to make safer, more accurate mine detection systems.

Seeing through Dust and Gas: Imaging the Universe

As telescopes have evolved from crude spyglass models to sophisticated satellites that orbit the Earth, our understanding of the universe has grown in leaps and bounds. This is because we have been able to see farther into the visible universe, and because advances in technology have enabled us to see the universe in different kinds of light.

The two pictures below show the same object, a cloud of gas and dust in space called a nebula. The picture on the left shows the nebula in visible light, and the picture on the right shows the nebula in near infrared light (with color added to show the contrasts).

Nicmos (the Near Infrared Camera and Multi-Object Spectrometer) peels away layers of dust to show the inner region of a dusty nebula.

The picture taken in visible light (left) contains a lot of information about the nebula, but in the upper right corner of the infrared picture (right) you will see a number of stars that do not appear in the visible picture. This is because there is a lot of gas and dust between the stars and the camera. Visible light coming from the stars is obscured by the dust and gas, but infrared light coming from the stars passes right though it. Infrared images often show more details about the structure of objects in space because it lets us see through surrounding gas and dust.

In addition to learning more about objects we already know, looking at the sky in infrared light shows us things that are otherwise invisible. For example, brown dwarfs are objects that are sort of in the middle between regular stars and giant gas planets like Jupiter. Brown dwarfs don’t give off visible light, but they do give off infrared light that we can detect.

This image shows two young brown dwarfs, objects that fall somewhere between planets and stars in terms of their temperature and mass.

Image credit: NASA/JPL-Caltech/Calar Alto Obsv./Caltech Sub. Obsv.

For more details on these and other uses of infrared light, check out the links in the next section.