An economical compact technology that uses visible-wavelength optics to analyze samples in the infrared, a technology that is expected to revolutionize medical and material testing.
Infrared spectroscopy can be used in materials analysis, forensics and cultural relics identification, but infrared spectroscopy scanners are bulky and expensive. The visible light band technology is relatively more economical and can be used on devices such as smartphone cameras and laser pens.
According to the James Consulting, Leonid Krivitsky and colleagues at the Data Storage Institute (DSI) subsidiary of the A*STAR Institute in Singapore used this idea to develop a “low-energy beam that can convert one laser into two beams. Method: Using the correlation of the two beams, it is possible to detect the infrared band beam in the visible light beam.
“This is a very simple and compact device that can be implemented with simple optics,” Krivitsky said. “We have achieved resolutions comparable to traditional infrared systems.” The
research team projected the laser into tannic acid. A lithium crystal that splits part of the laser photon into two low-energy quantum-related photons through a nonlinear process called "parametric down-conversion", one in the infrared and the other in the visible range.
In a device similar to the Michelson interferometer, the three beams are split and projected onto a mirror to reflect it back into the crystal. When the original laser beam re-enters the crystal, a new pair of down-converted beams are created that interfere with the beam produced by the first injection into the crystal.
The research team is using this kind of interference: the sample placed in the infrared beam affects the interference between the first down-conversion and the second down-converted beam, since the infrared beam is quantum-associated with the visible beam, this effect It can be detected in the beams of these two bands.
This method not only analyzes the change of infrared beam through visible light, but also provides more information than traditional spectroscopy. “Because this is an interferometric measurement, we can measure the absorptivity and refractive index of the beam independently, which is not possible with conventional infrared spectrometers,” Krivitsky said. The research team can systematically change the position of the sample in the beam. Get more information about the sample. Using these measurements, researchers can use optical coherence tomography to construct three-dimensional images of samples.
According to Krivitsky, “This is a very influential concept. It is also the perfect combination of spectroscopy, imaging and the ability to widely adjust wavelengths.” The team used this technology to analyze four wavelengths between 1.5 and 3 microns. Samples in the process, while previously analyzing samples at these wavelengths requires complex lasers and detectors.
The application of this technology can also be extended to the near-infrared and far-infrared bands by externally connecting the corresponding optical components. Krivitsky said: "As far as we know, there is currently no optical coherence tomography system available in the market beyond the 1.5 micron range."
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