25 April 1990 Velocity Measurement By The Optical Velocimeter Using The Double-Exposure Specklegram
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An optical velocimeter using a double-exposure specklegram is proposed and studied. In the method, a double-exposure specklegram is used to produce Young's fringes over a probing area, instead of forming the fringes as the result of interference of two beams in the case of a differential-type laser Doppler velocimeter. The method has special advantages over the conventional laser Doppler velocimetry such as simplicity in the optical arrangement together with high stability for mechanical shock. The power spectrum to be obtained in the present method was first theoretically derived, especially under the existence of speckle noise. Next, the velocities of the solid objects having continuous surfaces as well as the fluid flow or particles in the fluid were measured to show the usefulness of the method for actual objects. In the study, two types of the specklegram were considered in relation to the improvement of the signal-to-noise ratio (SNR) of the detected signal. The velocity of the solid object having relatively small variation of the surface brightness was accurately measured with an error less than 1 in the experiment.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
H. Kadono, H. Kadono, S. Toyooka, S. Toyooka, } "Velocity Measurement By The Optical Velocimeter Using The Double-Exposure Specklegram", Proc. SPIE 1162, Laser Interferometry: Quantitative Analysis of Interferograms: Third in a Series, (25 April 1990); doi: 10.1117/12.962750; https://doi.org/10.1117/12.962750

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