Measurement of the effective refractive index of a turbid colloidal suspension using light refraction

Refractive index measurement of turbid media by transmission of backscattered light near the critical angle

“…The coherent component corresponds to the average of the electromagnetic fields over all the permitted microscopic configurations of the system, whereas the diffuse component relates to the fluctuations of the electromagnetic fields around its average [1,5,[14][15][16]19,20,25]. When scattering is strong the coherent component decays rapidly within the bulk of the material and all is converted to diffuse light or absorbed.…”

“…When absorption by the material is small, most of the energy flux is carried by the diffuse component. The effective RI assigned to the coherent component of light has been investigated in recent years [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], and its nonlocal nature has been established [19,25]. However, as already said the effective RI seen by diffuse light has been barely investigated, and the only reference reporting efforts in the past that helps address this question is that of Meeten and North [6].…”

“…The concept and measurement of the effective RI has been associated only with the so-called coherent component of light [11,[14][15][16][17]19,25]. Therefore its measurement in turbid media has been pursued primarily using the propagation or reflection of the coherent component of light.…”

Refractive index investigation of poly(vinyl alcohol) films with TiO2 nanoparticle inclusions

“…As can be found in the published papers, there are some reported experimental methods to measure the effective RI of a turbid suspension with nanoparticles [12,13], but in the present work, the method of the disappearing diffraction pattern at a critical angle at two different wavelengths (laser microrefractometer [11]) is employed. This method for surface RI measurement was chosen based on its high accuracy.…”

Determination of refractive index for absorbing spheres

“…Several studies have been conducted to retrieve the refractive index by performing the extinction experiments [4,5]. Light refraction was also used to measure effective refractive index of a turbid colloidal suspension [6]. It is noted that the imaginary part of the refractive index is related to the light absorption.…”