Thanks to a range of developments in technology, systems based on terahertz technology are poised to enter and create significant new markets within the decade. A recently published market study by Thintri, Inc. highlights significant commercial opportunities in terahertz technology this decade. Of the many potential applications of terahertz radiation, manufacturing is potentially the most promising.
The terahertz portion of the electromagnetic spectrum is vaguely defined but is basically the band between infrared and microwave radiation, usually considered to run from 300 GHz to perhaps 10 THz, overlapping those bands commonly referred to as submillimeter and far infrared.
Terahertz radiation is a critical concern in astronomy, given that approximately one half the total luminosity of the universe and 98% of the photons emitted in the history of the universe lie in the terahertz portion of the spectrum, and that terahertz waves are not scattered by gas clouds in space.
Terahertz waves are reflected by metallic surfaces and absorbed by water, both of which remain opaque to terahertz signals. However, most other materials are transparent to terahertz radiation, to varying degrees. Terahertz systems can provide both images and spectroscopic data, (possibly in the same measurement), and ranging data that can measure coating or layer thicknesses, even in structures of many layers.
A number of technical breakthroughs in photonics, electronics and nanotechnology have occurred since the early 1990s which have brought terahertz technology within striking distance of significant commercial markets like security, communications, nondestructive evaluation, medicine and electronics. Bulk and ease of use have been longstanding issues with terahertz technology, but recently developed systems are as easy to use as an oscilloscope, and some are so small and robust that they can be delivered through the mail.
While development continues on components, attention is shifting to development of applications that are now ready to take advantage of the extraordinary versatility of the terahertz band. Indeed, application and market development are now the primary hurdles in the way of creation of significant markets for terahertz systems in such promising applications as manufacturing.
Terahertz technology has been promoted for an astonishingly wide range of applications:
- Manufacturing: real-time, in-situ process control, product inspection and material evaluation
- Food: food inspection for spoilage and contamination, determining the water content of food
- Biomedicine: mammography, bone tomography, endoscopy, medical diagnostics, detection of skin cancer and other diseases, identification of drugs or other substances in the blood, genetic sequencing
- Security and defense: detection of concealed weapons and explosives; evaluation of biological threats; airline passenger screening; detection of contraband in luggage, shipping containers; inspecting or reading unopened mail
- Imaging: imaging the contents of packages, sealed documents or closed books, fossils or oil encased in rock
- Scientific: environmental sensing, pollution detection, plasma diagnostics, chemistry and biochemistry
- And many more.
Terahertz radiation's main advantage is its ability to penetrate an extraordinary range of materials. It has been used to image through drywall to locate studs and wiring; to peer inside a closed bottle of tablets to ensure their quality without disturbing the contents; to measure the moisture content of packaged cigarettes; to image through plastic, paper, cardboard and most common fabrics.
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