WHY THIS MATTERS IN BRIEF
Sometimes we want to be able to see inside of objects, and using the quirkiness of terahertz radiation now we can like never before.
Recently I talked about a weird new type of technology called Photoacoustics that uses light, in the form of lasers, to create noises that can be used for crowd control as well as freaking people out and beaming adverts into people’s ears from a distance, and that can also be used to scan and see people’s insides from a distance that would be both a major privacy intrusion as well as offering some significant healthcare benefits.
Now though a group of researchers from the University of Sussex in the UK have taken this latter application and created a laser based Terahertz Camera that uses laser light patterns to see inside solid objects that reveal even the tiniest hidden features of living things.
An demo of the results
Furthermore, when combined with some of the new depth of field smartphone cameras that companies like Samsung have been showing off that let you scan the exterior of an object and then send that image to a 3D printer to be manufactured terahertz cameras could eventually let us scan and 3D print objects in their entirety with all their exterior and interior details and quirks intact. The technology also has many other use cases too including biometric identification and so on – something that’s not been lost on the US Military who are using similar technology to ID people using just their heartbeats from a distance.
Images produced using this technique are called hyperspectral because the image consists of pixels, each one containing the electromagnetic signature of the object in that point.
Lying between microwaves and infrared in the electromagnetic spectrum, Terahertz (THz) radiation easily penetrates materials like paper, clothes, and plastic in the same way X-rays do, but without being harmful, and it’s apparently safe to use with even the most delicate biological samples. THz imaging also makes it possible to “see” the molecular composition of objects and distinguish between different materials – such as sugar and cocaine, for example.
Explaining the significance of their achievement, Prof Peccianti, who led the research, said: “The core challenge in [developing] terahertz cameras is not about collecting an image, but it is about preserving the objects spectral fingerprint that can be easily corrupted by your technique. This is where the importance of our achievement lies. The fingerprint of all the details of the image is preserved in such a way that we can investigate the nature of the object in full detail.”
Until now, cameras capable of capturing a hyperspectral image preserving all the fine details revealed by THz radiation had not been considered possible.
The EPic Lab team used a single-pixel camera to image sample objects with patterns of THz light. The prototype they built can detect how the object alters different patterns of THz light. By combining this information with the shape of each original pattern, the camera reveals the image of an object as well as its chemical composition.
Sources of THz radiation are very faint and hyperspectral imaging had, until now, limited fidelity. To overcome this, the team shone a standard laser onto a unique non-linear material capable of converting visible light to THz. The prototype camera creates THz electromagnetic waves very close to the sample, similar to how a microscope works. As THz waves can travel right through an object without affecting it, the resulting images reveal the shape and composition of objects in three dimensions.
Prof Peccianti added, “This is a major step forward because we have demonstrated that all the possibilities explored in our previous theoretical research are not only feasible, but our camera works even better than we expected. While building our device, we discovered several ways to optimize the imaging process and now the technology is stable and works well. The next phase of our research will be in speeding up the image reconstruction process and taking us closer to applying THz cameras to real-world applications; like airport security, intelligent car sensors, quality control in manufacturing and even scanners to detect health problems like skin cancer.”
Source: DOI 10.1364/OPTICA.381035