Measurement of refractive index of hemoglobin in the visible/NIR spectral range

Abstract

This study is focused on the measurements of the refractive index of hemoglobin solutions in the visible/near-infrared (NIR) spectral range at room temperature for characteristic laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 930, 1100, 1300, and 1550 nm. Measurements were performed using the multiwavelength Abbe refractometer. Aqua hemoglobin solutions of different concentrations obtained from human whole blood were investigated. The specific increment of refractive index on hemoglobin concentration and the Sellmeier coefficients were calculated.

Measurement of tissue optical properties in the context of tissue optical clearing

“…The possibility of implementation of the refractometric method for revealing critical temperatures corresponding to phase transitions in tissues and cell structures was also demonstrated on the examples of human and porcine ATs. The obtained data for RI and its temperature increments for AT, Table 6 RI of human hemoglobin (260 g∕l) and albumin (55 g∕l) solutions, specific increment (α), and temperature increment (dn∕dT ) 112,113,116 Wavelength (nm) Hemoglobin Albumin human hemoglobin, and albumin are the new data supplementary to the data available in the literature. 17,87,103,123 It is important to note that in addition to classical refractometry, the spatially resolved phase imaging methods allowing for quantitative determination of RI distribution in tissues and cells are rapidly developing.…”

“…Since blood contains hemoglobin, one of the major chromophores of soft tissues in the visible/NIR region, it is of great importance to know the optical properties of both whole blood and its components. 113,114,[123][124][125] Measurement of RI of blood is of interest for many fields of optical biomedical diagnostics, including optical tomography and biopsy. 82 In the recent pilot study, 112…”

“…where n H 2 O is the RI of distilled water; C is the hemoglobin concentration; α is the specific refraction increment (see Table 6); 92,113,119 and dispersion is well described by Sellmeier equation: 113,114,126 E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 3 ; 3 2 6 ; 1 3 0…”

“…The fascicles were mounted in a slightly stretched state on an object-plate using binder clips and covered with a cover slip. Table 7 Coefficients of Sellmeier dispersion equation for human hemoglobin (260 g∕l) and albumin (55 g∕l) solutions 112,113,116 Solution In the measurements, an OCT-system ThorLabs-OCP930SR with a center wavelength (λ c ) of 930 nm was used. To estimate the average group RI n g of the tissue using OCT, a common method was employed, 93,[143][144][145] in which the group RI and physical thickness of the sample are determined from the measured values of the optical path length and shift of the image of a reflecting surface arranged beyond the sample with respect to its position in the absence of the sample [in our experimental geometry, as in Ref.…”

“…110 The refractometric properties of biological tissues and their individual components, such as human, porcine, and rat AT, porcine muscle tissue, rat brain tissue, and the main blood proteins-hemoglobin and albumin, have been studied in a wide range of wavelengths and temperatures. [111][112][113][114][115][116][117][118] The temperature dependences of RIs were analyzed for the presence of critical points corresponding to phase transitions. Figure 4 shows temperature dependence for the mean RI for abdominal human AT measured using multiwavelength Abbe refractometer DR-M2/1550 (Atago, Japan) at 930 nm and Table 1 The approximations for wavelength dependence of reduced scattering coefficient in the spectral range from 400 to 1300 nm for selected tissues.…”