A new laser Doppler particle measuring method which resists additive Gaussian noises is proposed. Particles are forced-vibrated by nonsinusoidal waves with fixed bispectral characteristics, and the responses are measured by using a velocity measuring system which consists of the optics of a laser Doppler velocimeter, FM discriminator, and a bispectral analyzer. Application of bispectral analysis is very effective in eliminating additive Gaussian noise even when the power of noise is fairly large. The principle, practical construction, and some experimental results are shown. The results show clearly the effectiveness of the method.
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