Loss of field of view due to optical mismatch at the inner diametric plane of cylindrical artificial microvessels

Abstract

In the experimental research with cylindrical artificial microvessels it may not be possible to view the entire inner diameter, due to optical mismatch between the microvessel material and the inside liquid suspension. A quantification of the field of view loss (FOVL) at the inner diametric plane is proposed, when the liquid suspension has a lower refractive index than the microvessel material and imaging is performed by a dry objective lens. A graphical model shows the optical ray tracing, utilizing 3 different refractive indices (η1, η2 and η3) for the microvessel material, the liquid suspension and the air. The numerical aperture (NA) of the objective lens defines the maximum ray output angle received by the lens and corresponds to a certain FOVL. Output angles were estimated for 8 different input angles and the corresponding FOVLs ranged from 71% down to 2%. The graphical model theoretical estimations were assessed experimentally for the cases of a water suspension and a plasma diluted blood sample (5% hematocrit). The theoretical estimations deviated only ±3% from the experimental assessments, showing that the graphical model could be a valuable tool for research on cylindrical artificial microvessels with dry objective lenses. © 2022