Holographic Ct Of The Basic Theory And Applied Research

Optical computed tomography (OCT) is an important product of optical measuring technique and tomography. It is a new nondestructive examination technique with high accuracy.OCT is used in the research of reconstruction of gas temperature field in this paper.Two parts are included:(1) the reconstruction of axisymmetric field: Spatial carrier phase-shifting method is used to real time holography detection of the axisymmetric gas field. A real time holographic experiment is done on the gas around a heating cord by single exposure method and two types of interferogram are obtained. By using holographic CT technique, the temperature fields are both calculated. The comparison results show that spatial carrier phase-shifting method is feasible and easy to practical application in real time holographic interferometry. Its accuracy is high. The characteristic of the method in real time holography detection is discussed.(2) the reconstruction of nonaxisymmetric field: The reconstruction algorithms have converter technique and series expansion technique mainly. Converter technique requires that interference fringes obtained must be in 180° angular field of view. And this is a high expectation of the holographic interferometric system. According to practicability, several major iterative algorithms of nonaxisymmetric temperature field reconstruction are summarized. Various influence factors of the OCT reconstruction accuracy are discussed. And some methods are given to increase its precision.At the same time, the relevant theories of holographic interferometry and OCT are introduced. For exemple, basic methods and phase measuring methods of holographic interferometry and phase unwrapping are introduced. Physical principle and mathematical foundation of CT and rudimentary algorithms of image reconstruction etc are also introduced.