Abstract: A time series signal multichannel frequency analyzer comprises a Fourier transform lens, a liquid crystal panel disposed at the front focal plane of the Fourier transform lens, means for inputting a time signal from a different signal source to each scanning line of the liquid crystal panel, observation means disposed at the rear focal plane of the Fourier transform lens, and a cylindrical lens disposed between the Fourier transform lens and an observation plane of the observation means.

Abstract: A device for the detection of the center of rotation of a rotating object under test comprises means for illuminating a laser beam on at least one position on the surface of the object thereby generating an interference fringe, means for subjecting the resultant reflected scattered laser beams to spectral analysis by the laser Doppler effect thereby finding the velocity of rotation of the position at which the interference fringe is formed on the surface, and means for determining the center of rotation on the basis of the velocity so found. Protection of the spectral analysis from the adverse effect of the pedestal component is accomplished by causing interference fringes to be formed at a plurality of positions on the surface of the object under test or by placing in the optical path for one of the pair of laser beams a prism capable of continuously modulating the laser frequency.

Abstract: A laser Doppler velocimeter using two laser beams, when used for the measurement of the flow velocity of slow moving particles, fails to provide the measurement because the Doppler frequency and the pedestal component overlap on the power spectrum. This difficulty is eliminated by having a prism disposed in the path of one of the laser beams used. When this prism is continuously moved, the pedestal component and the Doppler frequency are separated from each other on the power spectrum, enabling the velocimeter to effect the measurement easily and accurately.