Estimation and extraction of the aerosol complex refractive index based on Stokes vector measurements.

We present a way to estimate the aerosol complex refractive indices (ACRI) based on a real-time Stokes vector measurement technology. First, we introduce how to simultaneously get the multi-polarization signals of multi-scattering angles. Then we demonstrate the numerical inversion to retrieve an ACRI based on an iterative Mie algorithm. Meanwhile, we show the experimental results of several types of aerosol samples. Our optimal estimation of ACRI inversion shows a good agreement with the references, which confirms the feasibility and then implies a good prospect of multidimensional polarization characterization applied in the future aerosol recognition, especially suitable for near-spherical scatters.

High-temporal-resolution, full-field optical angiography based on short-time modulation depth for vascular occlusion tests.

We developed high-temporal-resolution, full-field optical angiography for use in vascular occlusion tests (VOTs). In the proposed method, undersampled signals are acquired by a high-speed digital camera that separates the dynamic and static speckle signals. The two types of speckle signal are used to calculate the short-time modulation depth (STMD) of each of the camera pixels. STMD is then used to realize high-temporal-resolution, full-field optical angiography. Phantom and biological experiments conducted and demonstrated the feasibility of using our proposed method to perform VOTs and to study the reaction kinetics in microfluidic systems.

Full-field velocity imaging of red blood cells in capillaries with spatiotemporal demodulation autocorrelation.

We propose a full-field optical method for the label-free and quantitative mapping of the velocities of red blood cells (RBCs) in capillaries. It integrates spatiotemporal demodulation and an autocorrelation algorithm, and measures RBC velocity according to the ratio of RBC length to lag time. Conventionally, RBC length is assumed to be a constant and lag time is taken as a variable, while our method treats both of them as variables. We use temporal demodulation and the Butterworth spatial filter to separate RBC signal from background signal, based on which we obtain the RBC length by image segmentation and lag time by autocorrelation analysis. The RBC velocity calculated now is more accurate. The validity of our method is verified by an in vivo experiment on a mouse ear. Owing to its higher image signal-to-noise ratio, our method can be used for mapping RBC velocity in the turbid tissue case.