High Speed Video System for Tissue Measurement Based on PWM Regulated Dimming and Virtual Instrumentation

摘要

Objects investigated by light transmission microscopy usually can't be highlighted using reflection marks or equipped with sensors of cinematic parameters. In this case we often use advantages of image analysis and signal processing. Some methods for frequency measurement (using photodiode and photomultiplier) of biomechanical or microscopic objects can't do the correct analysis of structure pathologies. The most progressive method is high speed digital video method, which brings relatively good results in formation of mathematical and mechanical model of structure movement [1]. On the other side, optimal light conditions in microscope can be achieved using various types of regulators (dimmers). Quality of obtained and analyzed digital images depends on acquisition system and its settings. Tissue measurement in modern medical praxis needs mutual cooperation of medicine, electronics and signal processing. As example of moving biomechanical system we can consider cilium of respiratory epithelium cell (Fig. 1). Each ciliated cell of respiratory epithelium contains ca. 200 cilias (6 μm long) beating with frequency up to 30 Hz. Cilias are synchronized with metachronal waves propagated in periciliar liquid. From the basic position cilium folds down to the epithelium cell (recovery stroke -75% of beating cycle) and then rapidly darts up to move mucus with its tip (effective stroke) [2]. Relatively high frequency of cilium movement leads to high requirements for the parts of acquisition system - microscope, camera, acquisition computer and others.