Research Of High-speed CCD Data Acquisition System And Image Spots Location

With the rapid development of opto-electronics and the semiconductor technology,optoelectronic devices have been widely used in various areas of the society.Among them,CCD can transform light to electricity and store information.It also has the merits such as small size,light weight,lower power consumption,low noise,good linearity,high sensitivity,large dynamic range,stable performance and strong self-scanning ability.These are the reasons that CCD is widely used in sensing image,measuring shape of object,examining project,storing and processing information.First of all,a high-speed linear CCD data acquisition system is researched and designed.How to choose a suitable CCD is an important issue in this design,so this paper starts with choosing CCD.After researching the working principle and performance character of different chips,the linear CCD—TCD1501D is chosen.And basing on deep study of driven sequential circuit of CCD and analysis of CCD signal characteristics,the CCD driver sequential circuit design is completed.This data acquisition system uses high-precision ADC,FIFO,DMA direct data storage and high-speed transmission technology,converts linear CCD pixel video signals to digital signals through high-speed A/D conversion,and sends it into a computer for real-time data processing and control.Comparing with other computer interfaces,parallel port has good reliability, shorter development cycle,low cost,high transfer rate,so parallel port is used as communication interface between the data acquisition system and computer. According to the requirements of industry measurement and parallel port data acquisition,a PC acquisition software using VC + + is developed.This software can directly control the collection through parallel port,obtain gray degree value,and at the same time,display them in graphic and text,making the results of acquisition more intuitive.It can also be directly applied to a variety of situations,provide a routine to user for further develop of more powerful platform.In this paper,CCD image spots positions subdivision method is used to enhance the precision of data acquisition system.The linear CCD subdivision location algorithm have the one dimension linearity compensation interpolation method,centroid interpolation method,proportional centrality method,center of gravity method,step-method,etc.These algorithm is to utilize the high relativity of gray degree value between the image elements for object image spots,and construct mathematics model that reflects accurately the object area image elements gray degree value and centroid location of object image spots as possible,so the accurate estimation of spot object images spots location.These method have been analyzed and deduced,and also the center of gravity method based on linear interpolation has been researched.Through analyzing measuring results,several important factors are obtained.The speed and precision of linear CCD data acquisition system have been greatly improved by the research in this paper,which has good prospects in areas such as industrial measurement.