The Research Of Laser Speckle Measure System Based On Correlation

Laser speckle is a ubiquitous statistical optics phenomenon, and it once is the natural enemy of hologram work, but now we research into it from the positive angle. Speckle measure technology is an important embranchment of modern optics measure, because it has many advantages, such as: non-contact, high response speed, simple experiment condition, low environmental factors requirements. With the development of laser technology, electronic technology and computer technology, the speckle measure technology is promoted. It develops along the path that is real-time, high speed and automatic. This paper uses the statistical theory of speckle and digital image processing technology to design a new experiment system by the correlation of speckle image. It can measure the radius of speckle and the plane displacement of rigid body.First, this paper illuminates laser speckle measure basic theory, measure method and the basis of digital image processing. It introduces laser speckle measure technology and instrument development survey, analyses the cause of laser speckle. In addition, this paper uses the self-correlation function to account the speckle which can describe granular shape from statistical theory. This paper also introduces the basis and method of digital image processing for speckle, addresses the measure theory based on laser speckle digital correlation technology.And then, a design plan of speckle measure system based on digital image correlation is proposed in this paper, including the hardware and software. The framework consists of the formation of speckle part, image-capturing part, preprocessing part and correlation computing part. Speckles are obtained, coming from the rough surface of glass by CCD camera and save the speckle image by video capture. The speckle image pre-processing consists of noise decreasing, image recognition and gray extending. This paper can calculate laser speckle statistical radius by fitting the function with the numerical value of the self-correlation calculation, it also can calculate plane displacement of rigid body by the cross-correlation of speckle image.Last, this paper conducts a test on laser digital speckle statistical radius and plane displacement of rigid body for the system. According to the experimental result, the system is proven to be reliable and stable. The paper summarizes the system's disadvantages and room for improvement, and predicts the foreground of applications in this system.