The SEED Project

From Terahertz Imaging to Terahertz Spectroscopy

Terahertz Imaging Scan

Although Terahertz technologies have been used for imaging for a while, Stimulated Emission Enhanced Detection is the most promising technology application and offers a vast improvement over conventional imaging and scanning.  Let’s look at these different technology and applications:

1. Terahertz Enhanced Imaging

The first application is THz imaging, a passive application that is essentially X-Rays on steroids, but still requires subjective interpretation of an image.

Terahertz Imaging Scan

“Well now, let me see, is that a notebook, a large sandwich, a brick of herion, or a block of C4?

2. Terahertz Linear Spectroscopy

The second application, also passive, is called ‘linear spectroscopy.’ This is where a known THz frequency is applied to a material and the resulting spectrographic ‘output’ is analyzed to determine what that material is.

In essence, linear spectroscopy is the ‘firing’ of a ‘THz bullet’ at an unknown material that can eventually be identified based on the forensic analysis of the fragmented remnants of the THz bullet.

The major shortcomings of this approach are (1) the resulting THz ‘fragmented remnants’ are exceptionally low in energy and impossible to detect from a standoff distance; (2) the THz ‘fragmented remnants’ must be detected from a location opposite of the applied THz ‘bullet’ .. tough to do when one does not know where an explosive is located to start with.

Terahertz Linear Spectroscopy


3. Terahertz Nonlinear Spectroscopy – SEED

The third and final application is Stimulated Emission Enhanced Detection or SEED – a non-passive, interrogative ‘nonlinear spectroscopy’ application where a known resonating THz frequency of the material in question is applied. If that material, an explosive in this case, is located within the frequency’s sweep, the material will absorb some of the applied resonating frequency’s energy.

This phenomenon is called ‘excitation.’  This is where the addition of a discrete amount of energy called excitation energy to a molecule results in a molecular alteration from its condition of lowest energy, or ground state, to one of higher energy; an excited state.

Terahertz Pulse


The Terahertz technologies of Stimulated Emission Enhanced Detection, or SEED, are the most promising technology application and offer a vast improvement over conventional imaging and scanning. This Terahertz nonlinear spectroscopy holds the most promise and is currently being developed by Alva Labs.


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