An angle-measuring technique based on an optical interferometer is reported. The technique exploits a Michelson interferometric configuration in which a right-angle prism and a glass strip are introduced into a probe beam. Simultaneous rotation of both components along an axis results in an optical path difference between the reference and the probe beams. In a second arrangement two right-angle prisms and glass strips are introduced into two beams of a Michelson interferometer. The prisms and the strips are rotated simultaneously to introduce an optical path difference between the two beams. In our arrangement, optimization of various parameters makes the net optical path difference between the two beams approximately linear for a rotation as great as +/-20 degrees . Results are simulated that show an improvement of 2-3 orders of magnitude in error and nonlinearity compared with a previously reported technique.

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The increase of glucose levels in blood changes the viscosity of flowing fluids and shape of the erythrocytes. Both of these can affect the details of light scattering as can be quantified via decorrelation times measured by optical coherence tomography (OCT). The relative contributions of these competing effects have been studied by examining the motion dynamics of deformable asymmetrical (red blood cells, RBCs with ~7 µm diameter and ~2 µm thickness) and non deformable symmetrical (polystyrene microspheres, PSM with 1.4 µm diameter) flowing scattering particles. The fluid flow under the action of gravity was mod ulated by changing the glucose concentrations. Quantitative analysis of the OCT's M mode autocorrelation functions enabled the derivations of the translational diffusion coefficients. These systematic studies are aimed at eventual tissue imaging scenarios with speckle variance OCT to obtain local glucose concentrations maps.

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