The Detection Of Underwater Bubbles Field Based On Digital Holography

Bubble field is an important medium for heat exchange between the Ocean and Atmosphere.It also plays a major influences on Internal Waves and ocean currents flow. With the research of marine, exploration of the bubble field plays a great significance on engineering technology and such others areas. There are plenty of techniques to get parameters. Of all the techniques, optical in-line holography has some particular advantages:non-destructive, wide size-range of the measured particles, large depth of field, directreconstruction of 3-D particle field, high resolution and simple set-up. Digital holography,digital recording of hologram offers an alternative recording and reconstruction in holography.The hologram generated by object is recorded directly by CCD and stored digitally by computer, and then reconstructed numerically.Combined with the advantages of digital feature of computer and three-dimensional image of holography,digitalholography has good prospects in optical metrology and has been widely applied invarious fields of science,engineering and biomedicine.Researches on digital holography and its application in particle field are the main purpose and contents of this dissertation.The work as follows,which centers about digital recording and numerical reconstruction and the analysis of reconstructed image,has been done in this dissertation.First, we introduced the principle of traditional optical holography and digital holography,the establishment of a digital hologram recording and numerical reconstruction of the mathematical model, the value of digital holography to reproduce the algorithm and the associated digital image processing method has been detailed theoretical analysis, Focuses on the recording and reconstruction process of in-line digital holography,applied to detect the bubble field.Second,there are two different reconstruction algorithms, Fresnel transform and the convolution.With analysis of the principle of the reconstruction algorithms completed the digital holographic recording and numerically reproduce the hologram, then select the bubble field Reappearance of the best reproduction program, and to make consequential amendments to reproduction proceduresThird,research the parameters of the experiment, according to the configuration of CCD and the related theory, calculate the CCD parameters on the record conditions. According to the complexity of the underwater environment, analyzing the underwater environment do the impact of holographic recording,make some changes to solve the impact.Detection of underwater digital holographic optical experiments carried out design changes.Digital holography applied to detection of underwater objects, carried out underwater bubble field digital holographic film experiment, and makes the digital reproduction.Last,with the experimental results,do error analysis of the light in the water and atmospheric refraction error, given compensation package.Paper organically integrated digital holographic technology and underwater bubble field detection technology,completed the numerical representation of underwater bubble field.The paper gives the data such as number and size of the underwater bubble field which can be used in further research.