Sticky Tape Found To Emit Terahertz Radiation

From Slashdot: Sticky Tape Found To Emit Terahertz Radiation.  Reading through the comments, this is more of an interesting curiosity than a practical discovery, but I find the explanation fascinating.  Terahertz-range radiation can be used for imaging, like C-rays.  Denser objects absorb more of the energy, so looking at the “shadow” from the other side of the object can show hidden weapons, etc.  Unlike C-rays, though, terahertz-range radiation does not harm the body.

Existing methods of producing radiation in this range tend to be large, bulky, and kinda expensive.  But don’t wring your hands and fork over investment money yet, because there are two big problems with this new technique; it produces very little radiation, and it’s incoherent.  In order to “see things” with radiation, a coherent stream of it must pass through the object being inspected, or you’ll just see a bunch of Bob Ross’s happy clouds.

Here’s a section from the article, but the comments on /. are more interesting to me (other than the one that said “I can see al qaeda ordering boat loads of it for a mass suicide tape pulling!”):

‘Peeling sticky tape has already been shown to produce X-rays, so Joseph Horvat and Roger Lewis of the University of Wollongong in New South Wales, Australia, tried to see if it could create lower-frequency terahertz radiation. “We were rather pleasantly surprised to obtain a clear signal in our first attempt,” says Horvat. Strongly adhesive Scotch Magic 810 tape and weakly adhesive electrical tape both yielded strong terahertz signals, ranging from 0.1 to 10 terahertz, but only about a microwatt of power, too little for practical use (Optics Letters, vol 34, p 2195). Horvat says that refinements should increase the power by orders of magnitude.’ It may be old news to Slashdot that [peeling clear tape] had been proved to produce X-rays, but watching the linked video where they use tape to expose X-ray film was pretty amazing.


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