Research Of Real-time Color Digital Holography Acquisition And Application To Detection

Color digital holography, as an important development of digital holography technology, has its advantages in nondestructive detection, such as non-touch and high accuracy. Multi-wavelengths record the information of materials from different angles at the same time. They can construct three non-coplanar vector fields in figure calculation and have high accuracy in detecting objects. However, color digital holography has many problems in the aspect of recording technology. Among them, the problem of real-time acquisition and color aliasing stands out the most. In order to improve its better application in the detection in material deformation fields, this dissertation does the research based on the technology recording and application of color digital holography. The main works are as following.Firstly, the present research findings are introduced according to the color digital holography and its measuring application and then the hot topics of the research both abroad and at home are discussed, for example, three dimensional topography, temperature field measurement, small physical quantity measurement and holographic microphotography, as well as the measurement of the same physical size of color digital holography and color correction and so on. The dissertation studies the recording and reconstruction principles of color digital holography, the split conditions of off-axis diffraction image and some common calculations of reconstruction. Several wave-front reconstructed calculations of color digital holography are also analyzed. The research of figure reconstruction of color digital holography is by means of magnification calculation.Then recording technology of color digital holography is researched with experiments. These experiments study the measurement of monochromatic record respectively. Although the formation of color hologram has non-color aliasing, it cannot meet the need of real-time acquisition. Real-time acquisition of color digital holography through the CCD of Bayer, RGB and Foveon is experimentally studied. By analyzing the reasons of color aliasing in reconstruction and CCD principles and by researching the ameliorated color aliasing based on the color correction with Foveon X3 CCD, the experimental result shows that the advanced Foveon X3 CCD and RGB CCD could apply in the real-time acquisition and detection of color digital holography.Finally, the dissertation analyzes and studies the relation between phase changing and displacement during the deformation of color digital holography. Besides, based on the real-time acquisition of color digital holography through the CCD of Bayer, dumbbell-shaped aluminum alloy plate is loaded pulling force by numerical control testing machine under normal temperature. The three dimensional deformation of test piece is recorded through color digital holography. The research also focuses on the deformation of test piece under the loaded pulling force in the high temperature. Through the three-dimensional deformation of titanium alloy in high temperature m measured by color digital holography, the inner displacement of test piece in the direction of pulling force will be calculated according to the changing relation between phase and displacement. Thus, the modulus of elasticity of the material will also be calculated according to the formula of the elastic modulus.This research findings show that the measurement of three-dimensional deformation by color digital holography can not only reconstruct three wavelength holograms and phase changing images and calculate the deformation quantity of materials well under normal temperature, but also have an accurate result of the deformation information under the high temperature. Therefore, the technology of color digital holography is quite practical in applications.