The digital speckle correlation method (DSCM) used to measure blood flow velocity is here analyzed. The experiment is designed to obtain the dynamic speckle pattern of blood which is shot by CCD. Then the DSCM is used to process the sequential images and the experiment is simulated. The experimental results show that the DSCM can measure blood flow velocity, and have a good agreement with the simulation results.
We investigate the evanescent field of a microfiber wrapped by colloidal crystals. The microfiber has the diameter of about 1 μm that is drawn from a single-mode fiber with an alcohol lamp. The colloidal spheres are further attached to the microfiber through thermal evaporation, then they self-assemble to crystal-like structures. The 400 nm, 590 nm, and 710 nm-diameter SiO2 colloidal spheres are used, respectively. The spectral responses are studied theoretically and experimentally, and the results agree with each other. It is revealed that the evanescent field of a microfiber could be modulated by the photonic band-gap of colloidal crystals. This characteristic is very useful in refractive index sensing for liquids.
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