Security screening applications as top terahertz radiation uses: Part I – mail & parcels inspection
As a leading manufacturer of terahertz imaging products we are happy to observe an increasingly growing interest in security applications of our THz technology employing non-invasive inspection methods. In a brief series of articles here we'd like to put into spotlight some of the fields that according to Google statistics rank as Top Terahertz Radiation Uses and feature among most popular and promising applications THz imaging technology that continue attracting a lot of attention from our customers all over the world.
All in all, security screening applications - with reference to THz imaging systems - can be subdivided further into two main sub-categories : -(A) Security screening of mail, small bags, packages, envelopes; and -(B) Security screening of people.
This article is dedicated to the first category (A) - Security screening of mail and other small and other flat containers, like small bags, packages, boxes etc. For these purposes we offer our terahertz imaging scanner systems that operate in transmission mode (i.e. suggests that a target objects/materials are placed between THz source and THz sensor array).
Designed for inspecting flat objects, our high speed THz imaging systems - including THz scanners at 300 GHz and at 100 GHz can perfectly handle such security inspection tasks, like checking mail packages, envelopes and small parcels for hidden objects and threats, contraband substance, drugs etc. THz images obtained in transmission mode allow seeing through envelopes (and many other conventional types of package viz, PE film, plastic, cardboard etc) and help identify potentially hazardous items inside without opening container or disturbing its integrity.
TeraSense offers two main elements for building the security scanners – a source with beam-shaping optics and a linear camera. The devices are compact and can be easily integrated into any conveyor system . The setups are optimized for 100 and 300 GHz and their main parameters are summarized in Table 1 . The 100-GHz arrangement provides better penetration but lower resolution. It can be applied for scanning of thick paper envelopes, cardboard packages and baggage made of fabrics, plastics, PVC and some other materials transparent of THz waves. The 300-GHz setup enables higher resolution scanning of paper envelopes and the linear THz camera consists of a line of GaAs semiconductor detectors for terahertz imaging.The systems can support very high e imaging speed up to 15m/sec.
The system includes sources based on high-powered semiconductor IMPATT (IMPact ionization Avalanche Transit-Time) diodes. IMPATT relies on negative resistance to generate and sustain an oscillation in the frequency range up to 300 GHz. The source is equipped with a high-gain horn antenna which emits divergent strip-like beam. The beam is further extended by the metallic mirror to cover the whole area of the linear camera .
HEALTH & SAFETY: Terasense technology employs terahertz waves, which are absolutely harmless for people and are therefore safe for operators and other staff involved in processing / delivery cycle. If required the inspected items (mails, envelopes) can be readjusted by-hand changing the field of view to obtain the most optimal THz image. The technology is light-weight and portable with a small footprint that ensures problem-free deployment in a small premises or constraint environment.
Visit our web-site to learn more about our technology and capabilities of our THz systems.