Diffraction Effect Of Low-frequency Liquid Surface Wave And Computer Simulation Of Surface Wave Shape Detection

Compared with the bulk, the liquid surface takes on some characteristics. One can obtain some parameters of liquid by means of researching them. Optical method is an important to detect the substance properties. Of course, this method is a good choice for the surface research as well. Regarding in the liquid surface properties measuring technique, the non- contact optical technique is one kind important method carries on optics to the liquid characteristic not to have damages, real-time, the intellectualized examination, has the very high measuring accuracy and the feasibility. This article utilizes the non- contact optical technique, mainly studies the liquid low-frequency surface wave characteristic and has established the interference -diffraction modulation effect intensity distribution and the liquid surface wave relations. This kind of interference - diffraction modulation effect may be used to measure some parameters of liquid, such as surface tension, surface wave length, amplitude, frequency, wave velocity, and so on. Next in view of several hertz low frequency surface waves, Fourier Transform method with a digital image processing technique is applied to measure some parameters of liquid the according to optics 3-D shape detection. This article studies the main content and the conclusion are as follows:1. High visible laser interference patterns from liquid surface acoustic waves (SAW) at a few tens Hertz were obtained experimentally. Modulation effect of interference patterns was observed and appeared as the disappearance of interference fringe in company with the variation of SAW amplitude. The intensity distribution of light, interference fringe and its characters are analyzed and the angle width of the interference fringe range with SAW was derived by theory of wave optics under the action of modulation. Moreover, based on the discovery, wavelength and amplitude of SAW and the distributive regularity of fringes light intensity were determined2. Take the above theory as the foundation, this article has established one new low frequency liquid surface wave frequency measuring technique, at the same time synchronized watches between the surface wave velocity and the wave length relations has conducted the experimental study. Takes the liquid sample from the liquid surfacewave be going to be measured, under driven by the low-frequency signal generator and the oscillator, determines wave length of the known frequency meter surface wave, according to the chromatic dispersion relations, extracts the liquid sample's surface tension;rests on the liquid surface wave interference - diffraction modulation effect, determines the liquid surface wave length be going to be measured, extracts the surface wave frequency once more according to the chromatic dispersion relations .If accurately knew the surface wave cycle and the wave length, could realize the surface wave velocity's survey, at the experiment has carried on the survey to various frequencies liquid surface wave propagation velocity, fitted the data ,has conducted the research to between the wave velocity and the wave length relations.3. In three dimensional face shape survey optical measurement method, because its measuring accuracy is high, the survey speed is quick, automated survey under the computer control is easy, has been widely applied. But the three dimensional face shape optical measurement method research majority aims at the static object, but in the dynamic process to be actually few, especially liquid surface wave face shape research. The dynamic liquid level face shape survey in liquid correlation research and superficial phenomenon, hydromechanics has the vital significance. This article uses in the three dimensional face shape survey Fourier transforms the outline law, has carried on the theoretical analysis to the dynamic three dimensional shape survey, Fourier transforms the outline method utilize to three dimensional shape, uses the CCD fast gain a series of distortions strip by the sine stripe project the dynamic change process liquid surface, by transforms, the frequency spectrum filter, counter Fourier after Fourier transforms, the three dimensional phase launches, obtains the reconstruction of a series of liquid level face shape, can reappear the dynamic liquid's change process, also can gain some characteristic parameters of liquid surface wave, has provided one new method for the liquid surface properties survey and the hydromechanics correlation research. While produces the theoretical analysis, has carried on the computer simulation proof.