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Optoelectronic sensory system for Raman spectromicroscopes
Gheorghe Gutt * , Valentin Popa, Mihai Dimian
1  Faculty of Electrical Engineering and Computer Science, Stefan cel Mare University of Suceava, 720229 Suceava, Romania

10.3390/I3S2021Dresden-10107 (registering DOI)

In order to obtain a high microscopic and spectral resolution, both for the microscopic study and for the spectrometric analysis carried out simultaneously at the same area on the sample, an adaptive optoelectronic system for Raman spectromicroscopes with the near-infrared excitation light source is designed. The current system and its working mode have a major disadvantage due to the fact the sample is moved several times to and from the focusing lens of the excitation radiation in the search for the focal point, in order to ensures the maximum spectral resolution. In this process, the peak height for the Stokes spectrum is monitored and the focal point is considered achieved when the peak heghit reaches its maximum. Due to the high energy density in a focal point, repeated searches of this point may lead to the modification of the chemical composition of the investigated material and, in some cases, even to the decomposition of some of its components.The paper presents an advanced technical solution that allows the microscopic study of the sample in the focal point of the visible spectrum, as well as the rapid and automatic search of the focal point in the Raman spectral analysis, at the 1064 nm wavelength in the near-infrared spectral domain, without thermally affecting the sample.

Keywords: Raman spectromicroscope; automatic focal point search