Can we consider terahertz imaging "infrared"? - Page 1
Forum section: electronics / general

author: frogg
author_rank: Regular Contributor
timestamp: December 19, 2019, 06:49:56 pm
content: Washington DC / WMATA has begun deploying real-time terahertz full-body scanners in the tunnel system. I use the WMATA metro system a lot and see them everywhere.They scanners are made by Thruvision and are fundamentally just passive terahertz imagers.Since terahertz scanners are probably going to become more common, especially in the security field, can we discuss them as infrared imagers, or is that technically incorrect?

author: Fraser
author_rank: Super Contributor
timestamp: December 19, 2019, 08:01:09 pm
content: To my understanding the term “Terahertz” is a band of the electro magnetic spectrum, just like the spectral band terms “Microwave” and “Infrared” between which it sits. Part of the Terahertz spectrum may be termed Far Infrared.A good article is to be found here....https://www.rp-photonics.com/terahertz_radiation.htmlTo be safe, it is often best to define the wavelength or frequency in a Terahertz discussion so that the reader knows where in the EM Spectrum the discussion is taking place.

author: Fraser
author_rank: Super Contributor
timestamp: December 19, 2019, 08:09:58 pm
content: Some more spectrum plans showing the “Terahertz Gap”

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 19, 2019, 10:28:51 pm
content: I second the recommendation to specify what you mean when you are discussing these. These descriptive terms have tended to be used as local shorthand by workers in the field, and vary over time, organization and country. Further obscured when military users of the bands attempt to hide or obscure their wavelengths of operation.There is no advantage I can see to calling them "infrared" other than making it clear that the human eyeball can't see the wavelengths involved. Using the term Terrahertz at least has the advantage of indicating a somewhat different part of the spectrum than traditional infrared or radars. Character of the optics/antenna systems or of the detection systems are sometimes suggested or used to separate the bands in question, but there is so much overlap in the Terrahertz range that this doesn't seem to be that useful.

author: Ultrapurple
author_rank: Super Contributor
timestamp: December 20, 2019, 10:09:49 am
content: In lieu of a dedicated THz board on EEVblog I would be perfectly happy to see THz matters discussed here.Yes there's a crossover with high frequency electronics but unless I'm much mistaken, THz imaging is still a very small niche within a niche so unless the electronics forum claims jurisdiction I can't see any reason why we shouldn't embrace those bands and techniques, provided (as others have said) it's clear what bands are being discussed. We already manage to deal with a bit of NIR, SWIR, MWIR and LWIR so VVLWIR shouldn't be a problem!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 20, 2019, 07:04:53 pm
content: I agree that until the field grows this is a perfectly good place to discuss THz imaging.

author: cvanc
author_rank: Frequent Contributor
timestamp: December 20, 2019, 07:18:05 pm
content: Forgive my ignorance, but what is THz imaging useful for?

author: Bill W
author_rank: Super Contributor
timestamp: December 20, 2019, 11:13:30 pm
content: But a Google/DDG away...https://terasense.com/applications/security/For some of the bands, the materials are similar and there is the use of germanium and heating of pixelsBill