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光子学报 2008
Signal to Noise Ratio Analysis for DNA Detecting System by Capillary Electrophoresis and Laser-induced Fluorescence
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Abstract:
A laser-induced fluorescence detection system for DNA capillary electrophoresis was set up.Propagation of exciting laser with normal incident angle was analyzed inside the capillary theoretically.Stray light of Rayleigh scattering by the electrophoresis sieving medium and that of refracting & reflecting by capillary tube walls were investigated.Background noise produced by refracting & reflecting was calculated by ray tracing arithmetic when collecting fluorescence at different deflecting angle from incident laser.The distribution curve was plotted.Fluorescence light intensity vs.the deflecting angle was investigated,too.Contributions to the influence on noise of the detecting system by Rayleigh scattering and by refracting & reflecting were compared.The result shows that the former is weaker for 4 orders,and could be omitted.Simulating experiment showed a uniform distribution of fluorescence.Minimum background noise was found at 105°,which gave the largest signal to noise ratio.The calculated result was validated by experiments.
