Laboratory image of a piece of flexible oil pipe being inspected with terahertz. The white, brown and yellow layers are stacked on top of each other and can be inspected simultaneously.

New photonic measurement technology is advancing

Tuesday 16 Nov 21


Simon Lehnskov Lange
DTU Electro
+45 22 98 77 99

About terahertz radiation

Terahertz radiation is electromagnetic waves that have a longer wavelength than visible light and infrared radiation, but a shorter wavelength than microwaves. The frequency is around one trillion hertz—hence the name—as the prefix tera means trillion. The frequency range is also called remote infrared radiation.

Using terahertz radiation, researchers at DTU Fotonik are demonstrating a new technology that can see through several layers and retrieve information about each separate layer simultaneously. 

They are aiming at a compact, inexpensive device that in no time can measure many different materials without destroying the measuring target. And they are making fast progress, the researchers at DTU Fotonik. Researcher Simon Lehnskov Lange is heading the research project, named GLAZE.

“Our new technology can see through a multilayer structure and retrieve information about each individual layer simultaneously,” says Simon Lehnskov Lange.

The technology is built upon terahertz radiation, which has the special property that it interacts strongly with the interfaces between many common materials.

“By seeing the interfaces, the user can measure the thicknesses of each layer, the layer adhesion and any potential layer inhomogeneities such as air bubbles,“ says Simon Lehnskov Lange, who adds, that contrary to X-rays, which are also commonly used for inspection of some materials, terahertz is harmless to humans due to its low energy.

First shrimps, then polymers

The DTU-magazine Dynamo has previously described the terahertz technology. Here the technology was praised for its huge potential to benefit industry worldwide, by being able to measure the thickness of innumerable materials.

Read the article Remote Infrared Radiation: New Technology Measures Thickness of Ice on Prawns

“We have previously used our terahertz system to measure the glazing thickness of frozen shrimps. Now, we are going to solve the same core problem, but this time in coatings of different materials,” says Simon Lehnskov Lange.

In collaboration with the company NOV Inc., the research team is going to use their proprietary terahertz system to inspect the thickness, adhesion and amount of air bubbles in the outermost polymer layers of flexible pipes.

The extruded polymer cover layers are used for temperature insulation, protection from the outer environment and general structural stability of the pipes, which are used for subsea transportation of oil, gas and CO2. Therefore, it is critical that they live up to very high specification standards. 

“We are going to ensure that the extrusion quality lives up these standards such that the pipes do not crack or erode too quickly,” says Simon Lehnskov Lange, and continues: 

“Once we have demonstrated the usefulness and business case of our solution with NOV Inc., it is time to go one step further to investigate if we can play a central role in improving the pipes supporting their use for transport of CO2 for carbon capture storage (CCS). To realize an infrastructure for CCS, we need to ensure that CO2 can be transported in a condensed form, e.g. as a high-pressure gas or even a liquid. CO2 is extremely harsh in these forms, which leads to significantly increased requirements for both inner and outer extruded layers of the pipes. Our current research work with NOV Inc. is, therefore, a step towards hopefully contributing to large scale energy infrastructure projects in both short and long terms.”

Simon Lehnskov Lange is confident, that the results of this collaboration will showcase the broad application span of this technology. His vision is that the technology will make it easy and inexpensive to measure and improve in all sectors of society:

 “Our innovative step from a business point of view is to translate a new methodology from the food sector into the heavy industry sector. We envision that we can repeat such translation in the future into other sectors as well.“ 

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