A new system for capturing hyperspectral images (those capable of collecting information throughout the entire electromagnetic spectrum), can operate in real time and provides a higher resolution than any other existing technology. This development could be a breakthrough for scientific and industrial applications related to chemical analysis.
This system, patented by the Sensors and Instrumentation Techniques group of the Carlos III University of Madrid (UC3M) in Spain, consists of a light source that allows a normal camera to be transformed into what is known as a hyperspectral camera. This technology makes it possible to obtain complete characterizations of the chemical composition of the sample being analyzed, by measuring the optical absorptions or molecular resonances that are characteristic of each compound. For this, an advanced analytical technique known as double comb spectroscopy is used.
Dual comb systems work by interfering light from two optical sources, called optical frequency combs. This mixing process generates a signal, called an interferogram, at a speed that, until very recently, was too fast to be captured by even very high-speed cameras.
The research team behind this patent has developed a system based on a double-comb electro-optical source, made with fiber optic components. The centerpiece is a dual-comb illuminator capable of generating two frequency combs that interfere at much lower frequencies than is possible with other systems. This makes it possible to detect this signal with any camera that has sensitivity in the emission range of the double comb system used. In addition, it is capable of working in different frequency ranges (near infrared, medium infrared and terahertz).
Example of capturing hyperspectral images, in this case for astronomy. (Illustration: IT. CC BY 4.0)
The technologies based on frequency combs used to date made it possible to analyze a single point of the sample, towards which the light source was sent. The system patented by the UC3M research team makes it possible to spectrally analyze the entire sample and is pioneering in terms of the measurement used because it uses a double frequency comb instead of the spectral interrogators that are equipped with current hyperspectral cameras.
From this characterization it can, in addition to identifying the compound, analyze other parameters such as its temperature, pressure and concentration. “The need arises from the shortcomings of current technologies, in which measurements are very slow and optical absorptions are not identified accurately enough. The high optical resolution with which we can characterize the entire sample with our technology is essential when we work, for example, with gases”, says Pedro Martín Mateos, professor in the Department of Electronic Technology at UC3M and researcher on the project.
This system allows the analysis of the chemical composition of a complete sample and can be used in many sectors. To date, it has been tested for the detection and analysis of gases, as well as for the study of the characteristics of different foods and materials, such as plastic. “We have already demonstrated its usefulness for the study of gaseous samples. This would be useful for the development of more efficient burners or for safety related issues. We have also used it for the analysis of certain foods and even for drying wood, and we are beginning to develop a system that will allow us to monitor combustion processes with new fuels or alternative fuels, such as hydrogen”, concludes the researcher. (Source: UC3M)