Researchers from the Universidad Carlos III de Madrid’s (UC3M’s) Sensors and Instrumentation Techniques group have patented a new hyperspectral imaging system that they say provides a higher resolution than any other existing technology.
The new system is made up of a light source that transforms a normal camera into a hyperspectral camera – capable of inspecting the chemical composition of a sample being analysed by measuring the optical absorptions/molecular resonances of each compound.
It relies on an advanced analytical technique known as dual-comb spectroscopy.
Here, light is interfered from two optical sources, called optical frequency combs, to generate a signal called an interferogram. This is done at a speed that, until very recently, was too fast to be captured even by very high-speed cameras, according to the UC3M researchers.
To overcome this challenge, they have used a dual-comb electro-optical source made with fibre optic components. The main part is a dual-comb illuminator capable of generating two frequency combs that interfere at much lower frequencies than can be obtained with other systems. This makes it possible to detect the signal with any camera that has sensitivity in the emission range of the dual-comb system used. In addition, it is capable of working in different frequency ranges (near-infrared, mid-infrared and terahertz).
Prior technologies based on frequency combs have been able to analyse a single point of a sample, towards which the light source was sent. The newly patented hyperspectral system is instead able to spectrally analyse an entire sample, and according to the researchers is pioneering in terms of the measurement used – as it uses a dual frequency comb instead of the spectral interrogators that current hyperspectral cameras are equipped with.
The system can, in addition to identifying chemical compounds in a sample, analyse other parameters such as its temperature, pressure and concentration. “The need arises from the shortcomings of current technologies, in which the measurements are very slow and optical absorptions are not identified precisely enough. The high optical resolution with which we can characterise the entire sample with our technology is essential when we work, for example, with gases”, said Pedro Martín Mateos, one of the UC3M researchers.
The patented system’s ability to analyse the chemical composition of complete samples makes it deployable in many sectors. To date, it has been tested for the detection and analysis of gases, as well as for studying the characteristics of different foods and materials, such as plastic. “We have already demonstrated its usefulness for the study of gaseous samples,” confirmed Mateos. “This would be useful for the development of more efficient burners or for safety issues. We have also used it for the analysis of certain foods and even for drying wood, and we are starting to develop a system that will allow us to monitor combustion processes with new fuels or alternative fuels, such as hydrogen.”
