CC BY
13B-I-23
BIOMEDICAL PHOTONICS
Refractive index measurement of the mouse skin in the visible wavelength range
M.A. Ansari1, *, M. Samani1, S. Ziaee1, E.A. Lazareva2, Yu.I. Surkov2,3, I.A. Serebryakova2,3, E.A. Genina2,3,
V.V. Tuchin234
1 - Laser and plasma research institute, Shahid Beheshti University, Tehran, Iran. 1983969411.
2 - Saratov State University, Astrakhanskaya str. 83, Saratov, 410012, Russia 3 - Tomsk State University, Lenin's av. 36, Tomsk, 634050, Russia 4 - Institute of Precision Mechanics and Control RAS, Rabochaya str. 24, Saratov, 410028, Russia
e-mail: m_ansari@sbu.ac.ir
The Refractive index is one of the most key factors in finding the different properties of the materials. So, its measurement could have different applications, such as medical applications. For example, it could be used in finding the type of the cancer tissues because of the different amount of their refractive index compared with the normal ones.
To measure the refractive index, different methods have been used, which have their advantages and disadvantages. One of these devices is the abbe refractometer. This device is used for finding the refractive index of the liquids at a single wavelength. The other one is a reflectometer system using a prism. This method is used for finding the refractive index for liquids and solids but at limited number of wavelengths.
The method presented here uses the Kramers-Kronig (KK) relation to find the refractive index. Using diffuse reflectance spectroscopy (DRS), the reflectance of the material could be measured with the use of an optical fiber in a visible wavelength range. The accuracy and precision of the KK method are evaluated using results obtained via commercial multi-wave refractometer (at 450, 480, 486, 546, 589, 644, 656, and 680 nm). The measured reflectance helps to find the refractive index using the KK relation in that range.
The point that makes this method special and better than other ones, is the measurement of the refractive index in the visible wavelength range (not just for a single amount of wavelength) and the useability for liquids and solids. Using this method, the refractive index of distilled water, glycerol, and the skin of the mouse is measured. The refractive index is measured before and during optical clearing of the skin using the immersion method. The optical clearing agent used, is a solution of 10% DMSO, 20% distilled water, and 70% glycerol. The temporal change in the content of water and the optical clearing agent in the skin is evaluated using optical coherence tomography (OCT). The results show that during the optical clearing the refractive index increases for some minutes and then decreases to be optically cleared after about 30 minutes.
This work is based upon research funded by Iran National Science Foundation (INSF) under project number 98029460 and Russian Foundation for Basic Research (RFBR) under project number 20-52-56005.
ALT'22
